1 /* $OpenBSD: sshd.c,v 1.585 2022/03/18 04:04:11 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include <sys/types.h> 46 #include <sys/ioctl.h> 47 #include <sys/wait.h> 48 #include <sys/tree.h> 49 #include <sys/stat.h> 50 #include <sys/socket.h> 51 #include <sys/time.h> 52 #include <sys/queue.h> 53 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <netdb.h> 57 #include <paths.h> 58 #include <poll.h> 59 #include <pwd.h> 60 #include <signal.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <stdarg.h> 65 #include <unistd.h> 66 #include <limits.h> 67 68 #ifdef WITH_OPENSSL 69 #include <openssl/bn.h> 70 #endif 71 72 #include "xmalloc.h" 73 #include "ssh.h" 74 #include "ssh2.h" 75 #include "sshpty.h" 76 #include "packet.h" 77 #include "log.h" 78 #include "sshbuf.h" 79 #include "misc.h" 80 #include "match.h" 81 #include "servconf.h" 82 #include "uidswap.h" 83 #include "compat.h" 84 #include "cipher.h" 85 #include "digest.h" 86 #include "sshkey.h" 87 #include "kex.h" 88 #include "myproposal.h" 89 #include "authfile.h" 90 #include "pathnames.h" 91 #include "atomicio.h" 92 #include "canohost.h" 93 #include "hostfile.h" 94 #include "auth.h" 95 #include "authfd.h" 96 #include "msg.h" 97 #include "dispatch.h" 98 #include "channels.h" 99 #include "session.h" 100 #include "monitor.h" 101 #ifdef GSSAPI 102 #include "ssh-gss.h" 103 #endif 104 #include "monitor_wrap.h" 105 #include "ssh-sandbox.h" 106 #include "auth-options.h" 107 #include "version.h" 108 #include "ssherr.h" 109 #include "sk-api.h" 110 #include "srclimit.h" 111 #include "dh.h" 112 113 /* Re-exec fds */ 114 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 115 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 116 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 117 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 118 119 extern char *__progname; 120 121 /* Server configuration options. */ 122 ServerOptions options; 123 124 /* Name of the server configuration file. */ 125 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 126 127 /* 128 * Debug mode flag. This can be set on the command line. If debug 129 * mode is enabled, extra debugging output will be sent to the system 130 * log, the daemon will not go to background, and will exit after processing 131 * the first connection. 132 */ 133 int debug_flag = 0; 134 135 /* 136 * Indicating that the daemon should only test the configuration and keys. 137 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 138 * configuration, optionally using connection information provided by the 139 * "-C" flag. 140 */ 141 static int test_flag = 0; 142 143 /* Flag indicating that the daemon is being started from inetd. */ 144 static int inetd_flag = 0; 145 146 /* Flag indicating that sshd should not detach and become a daemon. */ 147 static int no_daemon_flag = 0; 148 149 /* debug goes to stderr unless inetd_flag is set */ 150 static int log_stderr = 0; 151 152 /* Saved arguments to main(). */ 153 static char **saved_argv; 154 155 /* re-exec */ 156 static int rexeced_flag = 0; 157 static int rexec_flag = 1; 158 static int rexec_argc = 0; 159 static char **rexec_argv; 160 161 /* 162 * The sockets that the server is listening; this is used in the SIGHUP 163 * signal handler. 164 */ 165 #define MAX_LISTEN_SOCKS 16 166 static int listen_socks[MAX_LISTEN_SOCKS]; 167 static int num_listen_socks = 0; 168 169 /* Daemon's agent connection */ 170 int auth_sock = -1; 171 static int have_agent = 0; 172 173 /* 174 * Any really sensitive data in the application is contained in this 175 * structure. The idea is that this structure could be locked into memory so 176 * that the pages do not get written into swap. However, there are some 177 * problems. The private key contains BIGNUMs, and we do not (in principle) 178 * have access to the internals of them, and locking just the structure is 179 * not very useful. Currently, memory locking is not implemented. 180 */ 181 struct { 182 struct sshkey **host_keys; /* all private host keys */ 183 struct sshkey **host_pubkeys; /* all public host keys */ 184 struct sshkey **host_certificates; /* all public host certificates */ 185 int have_ssh2_key; 186 } sensitive_data; 187 188 /* This is set to true when a signal is received. */ 189 static volatile sig_atomic_t received_sighup = 0; 190 static volatile sig_atomic_t received_sigterm = 0; 191 192 /* record remote hostname or ip */ 193 u_int utmp_len = HOST_NAME_MAX+1; 194 195 /* 196 * startup_pipes/flags are used for tracking children of the listening sshd 197 * process early in their lifespans. This tracking is needed for three things: 198 * 199 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 200 * connections. 201 * 2) Avoiding a race condition for SIGHUP processing, where child processes 202 * may have listen_socks open that could collide with main listener process 203 * after it restarts. 204 * 3) Ensuring that rexec'd sshd processes have received their initial state 205 * from the parent listen process before handling SIGHUP. 206 * 207 * Child processes signal that they have completed closure of the listen_socks 208 * and (if applicable) received their rexec state by sending a char over their 209 * sock. Child processes signal that authentication has completed by closing 210 * the sock (or by exiting). 211 */ 212 static int *startup_pipes = NULL; 213 static int *startup_flags = NULL; /* Indicates child closed listener */ 214 static int startup_pipe = -1; /* in child */ 215 216 /* variables used for privilege separation */ 217 int use_privsep = -1; 218 struct monitor *pmonitor = NULL; 219 int privsep_is_preauth = 1; 220 221 /* global connection state and authentication contexts */ 222 Authctxt *the_authctxt = NULL; 223 struct ssh *the_active_state; 224 225 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 226 struct sshauthopt *auth_opts = NULL; 227 228 /* sshd_config buffer */ 229 struct sshbuf *cfg; 230 231 /* Included files from the configuration file */ 232 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 233 234 /* message to be displayed after login */ 235 struct sshbuf *loginmsg; 236 237 /* Prototypes for various functions defined later in this file. */ 238 void destroy_sensitive_data(void); 239 void demote_sensitive_data(void); 240 static void do_ssh2_kex(struct ssh *); 241 242 static char *listener_proctitle; 243 244 /* 245 * Close all listening sockets 246 */ 247 static void 248 close_listen_socks(void) 249 { 250 int i; 251 252 for (i = 0; i < num_listen_socks; i++) 253 close(listen_socks[i]); 254 num_listen_socks = 0; 255 } 256 257 static void 258 close_startup_pipes(void) 259 { 260 int i; 261 262 if (startup_pipes) 263 for (i = 0; i < options.max_startups; i++) 264 if (startup_pipes[i] != -1) 265 close(startup_pipes[i]); 266 } 267 268 /* 269 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 270 * the effect is to reread the configuration file (and to regenerate 271 * the server key). 272 */ 273 274 /*ARGSUSED*/ 275 static void 276 sighup_handler(int sig) 277 { 278 received_sighup = 1; 279 } 280 281 /* 282 * Called from the main program after receiving SIGHUP. 283 * Restarts the server. 284 */ 285 static void 286 sighup_restart(void) 287 { 288 logit("Received SIGHUP; restarting."); 289 if (options.pid_file != NULL) 290 unlink(options.pid_file); 291 close_listen_socks(); 292 close_startup_pipes(); 293 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 294 execv(saved_argv[0], saved_argv); 295 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 296 strerror(errno)); 297 exit(1); 298 } 299 300 /* 301 * Generic signal handler for terminating signals in the master daemon. 302 */ 303 /*ARGSUSED*/ 304 static void 305 sigterm_handler(int sig) 306 { 307 received_sigterm = sig; 308 } 309 310 /* 311 * SIGCHLD handler. This is called whenever a child dies. This will then 312 * reap any zombies left by exited children. 313 */ 314 /*ARGSUSED*/ 315 static void 316 main_sigchld_handler(int sig) 317 { 318 int save_errno = errno; 319 pid_t pid; 320 int status; 321 322 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 323 (pid == -1 && errno == EINTR)) 324 ; 325 errno = save_errno; 326 } 327 328 /* 329 * Signal handler for the alarm after the login grace period has expired. 330 */ 331 /*ARGSUSED*/ 332 static void 333 grace_alarm_handler(int sig) 334 { 335 /* 336 * Try to kill any processes that we have spawned, E.g. authorized 337 * keys command helpers or privsep children. 338 */ 339 if (getpgid(0) == getpid()) { 340 ssh_signal(SIGTERM, SIG_IGN); 341 kill(0, SIGTERM); 342 } 343 344 /* Log error and exit. */ 345 sigdie("Timeout before authentication for %s port %d", 346 ssh_remote_ipaddr(the_active_state), 347 ssh_remote_port(the_active_state)); 348 } 349 350 /* Destroy the host and server keys. They will no longer be needed. */ 351 void 352 destroy_sensitive_data(void) 353 { 354 u_int i; 355 356 for (i = 0; i < options.num_host_key_files; i++) { 357 if (sensitive_data.host_keys[i]) { 358 sshkey_free(sensitive_data.host_keys[i]); 359 sensitive_data.host_keys[i] = NULL; 360 } 361 if (sensitive_data.host_certificates[i]) { 362 sshkey_free(sensitive_data.host_certificates[i]); 363 sensitive_data.host_certificates[i] = NULL; 364 } 365 } 366 } 367 368 /* Demote private to public keys for network child */ 369 void 370 demote_sensitive_data(void) 371 { 372 struct sshkey *tmp; 373 u_int i; 374 int r; 375 376 for (i = 0; i < options.num_host_key_files; i++) { 377 if (sensitive_data.host_keys[i]) { 378 if ((r = sshkey_from_private( 379 sensitive_data.host_keys[i], &tmp)) != 0) 380 fatal_r(r, "could not demote host %s key", 381 sshkey_type(sensitive_data.host_keys[i])); 382 sshkey_free(sensitive_data.host_keys[i]); 383 sensitive_data.host_keys[i] = tmp; 384 } 385 /* Certs do not need demotion */ 386 } 387 } 388 389 static void 390 privsep_preauth_child(void) 391 { 392 gid_t gidset[1]; 393 struct passwd *pw; 394 395 /* Enable challenge-response authentication for privilege separation */ 396 privsep_challenge_enable(); 397 398 #ifdef GSSAPI 399 /* Cache supported mechanism OIDs for later use */ 400 ssh_gssapi_prepare_supported_oids(); 401 #endif 402 403 /* Demote the private keys to public keys. */ 404 demote_sensitive_data(); 405 406 /* Demote the child */ 407 if (getuid() == 0 || geteuid() == 0) { 408 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 409 fatal("Privilege separation user %s does not exist", 410 SSH_PRIVSEP_USER); 411 pw = pwcopy(pw); /* Ensure mutable */ 412 endpwent(); 413 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 414 415 /* Change our root directory */ 416 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 417 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 418 strerror(errno)); 419 if (chdir("/") == -1) 420 fatal("chdir(\"/\"): %s", strerror(errno)); 421 422 /* 423 * Drop our privileges 424 * NB. Can't use setusercontext() after chroot. 425 */ 426 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 427 (u_int)pw->pw_gid); 428 gidset[0] = pw->pw_gid; 429 if (setgroups(1, gidset) == -1) 430 fatal("setgroups: %.100s", strerror(errno)); 431 permanently_set_uid(pw); 432 } 433 } 434 435 static int 436 privsep_preauth(struct ssh *ssh) 437 { 438 int status, r; 439 pid_t pid; 440 struct ssh_sandbox *box = NULL; 441 442 /* Set up unprivileged child process to deal with network data */ 443 pmonitor = monitor_init(); 444 /* Store a pointer to the kex for later rekeying */ 445 pmonitor->m_pkex = &ssh->kex; 446 447 if (use_privsep == PRIVSEP_ON) 448 box = ssh_sandbox_init(); 449 pid = fork(); 450 if (pid == -1) { 451 fatal("fork of unprivileged child failed"); 452 } else if (pid != 0) { 453 debug2("Network child is on pid %ld", (long)pid); 454 455 pmonitor->m_pid = pid; 456 if (have_agent) { 457 r = ssh_get_authentication_socket(&auth_sock); 458 if (r != 0) { 459 error_r(r, "Could not get agent socket"); 460 have_agent = 0; 461 } 462 } 463 if (box != NULL) 464 ssh_sandbox_parent_preauth(box, pid); 465 monitor_child_preauth(ssh, pmonitor); 466 467 /* Wait for the child's exit status */ 468 while (waitpid(pid, &status, 0) == -1) { 469 if (errno == EINTR) 470 continue; 471 pmonitor->m_pid = -1; 472 fatal_f("waitpid: %s", strerror(errno)); 473 } 474 privsep_is_preauth = 0; 475 pmonitor->m_pid = -1; 476 if (WIFEXITED(status)) { 477 if (WEXITSTATUS(status) != 0) 478 fatal_f("preauth child exited with status %d", 479 WEXITSTATUS(status)); 480 } else if (WIFSIGNALED(status)) 481 fatal_f("preauth child terminated by signal %d", 482 WTERMSIG(status)); 483 if (box != NULL) 484 ssh_sandbox_parent_finish(box); 485 return 1; 486 } else { 487 /* child */ 488 close(pmonitor->m_sendfd); 489 close(pmonitor->m_log_recvfd); 490 491 /* Arrange for logging to be sent to the monitor */ 492 set_log_handler(mm_log_handler, pmonitor); 493 494 privsep_preauth_child(); 495 setproctitle("%s", "[net]"); 496 if (box != NULL) 497 ssh_sandbox_child(box); 498 499 return 0; 500 } 501 } 502 503 static void 504 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 505 { 506 if (authctxt->pw->pw_uid == 0) { 507 /* File descriptor passing is broken or root login */ 508 use_privsep = 0; 509 goto skip; 510 } 511 512 /* New socket pair */ 513 monitor_reinit(pmonitor); 514 515 pmonitor->m_pid = fork(); 516 if (pmonitor->m_pid == -1) 517 fatal("fork of unprivileged child failed"); 518 else if (pmonitor->m_pid != 0) { 519 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 520 sshbuf_reset(loginmsg); 521 monitor_clear_keystate(ssh, pmonitor); 522 monitor_child_postauth(ssh, pmonitor); 523 524 /* NEVERREACHED */ 525 exit(0); 526 } 527 528 /* child */ 529 530 close(pmonitor->m_sendfd); 531 pmonitor->m_sendfd = -1; 532 533 /* Demote the private keys to public keys. */ 534 demote_sensitive_data(); 535 536 /* Drop privileges */ 537 do_setusercontext(authctxt->pw); 538 539 skip: 540 /* It is safe now to apply the key state */ 541 monitor_apply_keystate(ssh, pmonitor); 542 543 /* 544 * Tell the packet layer that authentication was successful, since 545 * this information is not part of the key state. 546 */ 547 ssh_packet_set_authenticated(ssh); 548 } 549 550 static void 551 append_hostkey_type(struct sshbuf *b, const char *s) 552 { 553 int r; 554 555 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 556 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 557 return; 558 } 559 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 560 fatal_fr(r, "sshbuf_putf"); 561 } 562 563 static char * 564 list_hostkey_types(void) 565 { 566 struct sshbuf *b; 567 struct sshkey *key; 568 char *ret; 569 u_int i; 570 571 if ((b = sshbuf_new()) == NULL) 572 fatal_f("sshbuf_new failed"); 573 for (i = 0; i < options.num_host_key_files; i++) { 574 key = sensitive_data.host_keys[i]; 575 if (key == NULL) 576 key = sensitive_data.host_pubkeys[i]; 577 if (key == NULL) 578 continue; 579 switch (key->type) { 580 case KEY_RSA: 581 /* for RSA we also support SHA2 signatures */ 582 append_hostkey_type(b, "rsa-sha2-512"); 583 append_hostkey_type(b, "rsa-sha2-256"); 584 /* FALLTHROUGH */ 585 case KEY_DSA: 586 case KEY_ECDSA: 587 case KEY_ED25519: 588 case KEY_ECDSA_SK: 589 case KEY_ED25519_SK: 590 case KEY_XMSS: 591 append_hostkey_type(b, sshkey_ssh_name(key)); 592 break; 593 } 594 /* If the private key has a cert peer, then list that too */ 595 key = sensitive_data.host_certificates[i]; 596 if (key == NULL) 597 continue; 598 switch (key->type) { 599 case KEY_RSA_CERT: 600 /* for RSA we also support SHA2 signatures */ 601 append_hostkey_type(b, 602 "rsa-sha2-512-cert-v01@openssh.com"); 603 append_hostkey_type(b, 604 "rsa-sha2-256-cert-v01@openssh.com"); 605 /* FALLTHROUGH */ 606 case KEY_DSA_CERT: 607 case KEY_ECDSA_CERT: 608 case KEY_ED25519_CERT: 609 case KEY_ECDSA_SK_CERT: 610 case KEY_ED25519_SK_CERT: 611 case KEY_XMSS_CERT: 612 append_hostkey_type(b, sshkey_ssh_name(key)); 613 break; 614 } 615 } 616 if ((ret = sshbuf_dup_string(b)) == NULL) 617 fatal_f("sshbuf_dup_string failed"); 618 sshbuf_free(b); 619 debug_f("%s", ret); 620 return ret; 621 } 622 623 static struct sshkey * 624 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 625 { 626 u_int i; 627 struct sshkey *key; 628 629 for (i = 0; i < options.num_host_key_files; i++) { 630 switch (type) { 631 case KEY_RSA_CERT: 632 case KEY_DSA_CERT: 633 case KEY_ECDSA_CERT: 634 case KEY_ED25519_CERT: 635 case KEY_ECDSA_SK_CERT: 636 case KEY_ED25519_SK_CERT: 637 case KEY_XMSS_CERT: 638 key = sensitive_data.host_certificates[i]; 639 break; 640 default: 641 key = sensitive_data.host_keys[i]; 642 if (key == NULL && !need_private) 643 key = sensitive_data.host_pubkeys[i]; 644 break; 645 } 646 if (key == NULL || key->type != type) 647 continue; 648 switch (type) { 649 case KEY_ECDSA: 650 case KEY_ECDSA_SK: 651 case KEY_ECDSA_CERT: 652 case KEY_ECDSA_SK_CERT: 653 if (key->ecdsa_nid != nid) 654 continue; 655 /* FALLTHROUGH */ 656 default: 657 return need_private ? 658 sensitive_data.host_keys[i] : key; 659 } 660 } 661 return NULL; 662 } 663 664 struct sshkey * 665 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 666 { 667 return get_hostkey_by_type(type, nid, 0, ssh); 668 } 669 670 struct sshkey * 671 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 672 { 673 return get_hostkey_by_type(type, nid, 1, ssh); 674 } 675 676 struct sshkey * 677 get_hostkey_by_index(int ind) 678 { 679 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 680 return (NULL); 681 return (sensitive_data.host_keys[ind]); 682 } 683 684 struct sshkey * 685 get_hostkey_public_by_index(int ind, struct ssh *ssh) 686 { 687 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 688 return (NULL); 689 return (sensitive_data.host_pubkeys[ind]); 690 } 691 692 int 693 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 694 { 695 u_int i; 696 697 for (i = 0; i < options.num_host_key_files; i++) { 698 if (sshkey_is_cert(key)) { 699 if (key == sensitive_data.host_certificates[i] || 700 (compare && sensitive_data.host_certificates[i] && 701 sshkey_equal(key, 702 sensitive_data.host_certificates[i]))) 703 return (i); 704 } else { 705 if (key == sensitive_data.host_keys[i] || 706 (compare && sensitive_data.host_keys[i] && 707 sshkey_equal(key, sensitive_data.host_keys[i]))) 708 return (i); 709 if (key == sensitive_data.host_pubkeys[i] || 710 (compare && sensitive_data.host_pubkeys[i] && 711 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 712 return (i); 713 } 714 } 715 return (-1); 716 } 717 718 /* Inform the client of all hostkeys */ 719 static void 720 notify_hostkeys(struct ssh *ssh) 721 { 722 struct sshbuf *buf; 723 struct sshkey *key; 724 u_int i, nkeys; 725 int r; 726 char *fp; 727 728 /* Some clients cannot cope with the hostkeys message, skip those. */ 729 if (ssh->compat & SSH_BUG_HOSTKEYS) 730 return; 731 732 if ((buf = sshbuf_new()) == NULL) 733 fatal_f("sshbuf_new"); 734 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 735 key = get_hostkey_public_by_index(i, ssh); 736 if (key == NULL || key->type == KEY_UNSPEC || 737 sshkey_is_cert(key)) 738 continue; 739 fp = sshkey_fingerprint(key, options.fingerprint_hash, 740 SSH_FP_DEFAULT); 741 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 742 free(fp); 743 if (nkeys == 0) { 744 /* 745 * Start building the request when we find the 746 * first usable key. 747 */ 748 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 749 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 750 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 751 sshpkt_fatal(ssh, r, "%s: start request", __func__); 752 } 753 /* Append the key to the request */ 754 sshbuf_reset(buf); 755 if ((r = sshkey_putb(key, buf)) != 0) 756 fatal_fr(r, "couldn't put hostkey %d", i); 757 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 758 sshpkt_fatal(ssh, r, "%s: append key", __func__); 759 nkeys++; 760 } 761 debug3_f("sent %u hostkeys", nkeys); 762 if (nkeys == 0) 763 fatal_f("no hostkeys"); 764 if ((r = sshpkt_send(ssh)) != 0) 765 sshpkt_fatal(ssh, r, "%s: send", __func__); 766 sshbuf_free(buf); 767 } 768 769 /* 770 * returns 1 if connection should be dropped, 0 otherwise. 771 * dropping starts at connection #max_startups_begin with a probability 772 * of (max_startups_rate/100). the probability increases linearly until 773 * all connections are dropped for startups > max_startups 774 */ 775 static int 776 should_drop_connection(int startups) 777 { 778 int p, r; 779 780 if (startups < options.max_startups_begin) 781 return 0; 782 if (startups >= options.max_startups) 783 return 1; 784 if (options.max_startups_rate == 100) 785 return 1; 786 787 p = 100 - options.max_startups_rate; 788 p *= startups - options.max_startups_begin; 789 p /= options.max_startups - options.max_startups_begin; 790 p += options.max_startups_rate; 791 r = arc4random_uniform(100); 792 793 debug_f("p %d, r %d", p, r); 794 return (r < p) ? 1 : 0; 795 } 796 797 /* 798 * Check whether connection should be accepted by MaxStartups. 799 * Returns 0 if the connection is accepted. If the connection is refused, 800 * returns 1 and attempts to send notification to client. 801 * Logs when the MaxStartups condition is entered or exited, and periodically 802 * while in that state. 803 */ 804 static int 805 drop_connection(int sock, int startups, int notify_pipe) 806 { 807 char *laddr, *raddr; 808 const char msg[] = "Exceeded MaxStartups\r\n"; 809 static time_t last_drop, first_drop; 810 static u_int ndropped; 811 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 812 time_t now; 813 814 now = monotime(); 815 if (!should_drop_connection(startups) && 816 srclimit_check_allow(sock, notify_pipe) == 1) { 817 if (last_drop != 0 && 818 startups < options.max_startups_begin - 1) { 819 /* XXX maybe need better hysteresis here */ 820 logit("exited MaxStartups throttling after %s, " 821 "%u connections dropped", 822 fmt_timeframe(now - first_drop), ndropped); 823 last_drop = 0; 824 } 825 return 0; 826 } 827 828 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 829 if (last_drop == 0) { 830 error("beginning MaxStartups throttling"); 831 drop_level = SYSLOG_LEVEL_INFO; 832 first_drop = now; 833 ndropped = 0; 834 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 835 /* Periodic logs */ 836 error("in MaxStartups throttling for %s, " 837 "%u connections dropped", 838 fmt_timeframe(now - first_drop), ndropped + 1); 839 drop_level = SYSLOG_LEVEL_INFO; 840 } 841 last_drop = now; 842 ndropped++; 843 844 laddr = get_local_ipaddr(sock); 845 raddr = get_peer_ipaddr(sock); 846 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 847 "past MaxStartups", startups, raddr, get_peer_port(sock), 848 laddr, get_local_port(sock)); 849 free(laddr); 850 free(raddr); 851 /* best-effort notification to client */ 852 (void)write(sock, msg, sizeof(msg) - 1); 853 return 1; 854 } 855 856 static void 857 usage(void) 858 { 859 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION); 860 fprintf(stderr, 861 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 862 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 863 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 864 ); 865 exit(1); 866 } 867 868 static void 869 send_rexec_state(int fd, struct sshbuf *conf) 870 { 871 struct sshbuf *m = NULL, *inc = NULL; 872 struct include_item *item = NULL; 873 int r; 874 875 debug3_f("entering fd = %d config len %zu", fd, 876 sshbuf_len(conf)); 877 878 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 879 fatal_f("sshbuf_new failed"); 880 881 /* pack includes into a string */ 882 TAILQ_FOREACH(item, &includes, entry) { 883 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 884 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 885 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 886 fatal_fr(r, "compose includes"); 887 } 888 889 /* 890 * Protocol from reexec master to child: 891 * string configuration 892 * string included_files[] { 893 * string selector 894 * string filename 895 * string contents 896 * } 897 */ 898 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 899 (r = sshbuf_put_stringb(m, inc)) != 0) 900 fatal_fr(r, "compose config"); 901 if (ssh_msg_send(fd, 0, m) == -1) 902 error_f("ssh_msg_send failed"); 903 904 sshbuf_free(m); 905 sshbuf_free(inc); 906 907 debug3_f("done"); 908 } 909 910 static void 911 recv_rexec_state(int fd, struct sshbuf *conf) 912 { 913 struct sshbuf *m, *inc; 914 u_char *cp, ver; 915 size_t len; 916 int r; 917 struct include_item *item; 918 919 debug3_f("entering fd = %d", fd); 920 921 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 922 fatal_f("sshbuf_new failed"); 923 if (ssh_msg_recv(fd, m) == -1) 924 fatal_f("ssh_msg_recv failed"); 925 if ((r = sshbuf_get_u8(m, &ver)) != 0) 926 fatal_fr(r, "parse version"); 927 if (ver != 0) 928 fatal_f("rexec version mismatch"); 929 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 930 (r = sshbuf_get_stringb(m, inc)) != 0) 931 fatal_fr(r, "parse config"); 932 933 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 934 fatal_fr(r, "sshbuf_put"); 935 936 while (sshbuf_len(inc) != 0) { 937 item = xcalloc(1, sizeof(*item)); 938 if ((item->contents = sshbuf_new()) == NULL) 939 fatal_f("sshbuf_new failed"); 940 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 941 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 942 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 943 fatal_fr(r, "parse includes"); 944 TAILQ_INSERT_TAIL(&includes, item, entry); 945 } 946 947 free(cp); 948 sshbuf_free(m); 949 950 debug3_f("done"); 951 } 952 953 /* Accept a connection from inetd */ 954 static void 955 server_accept_inetd(int *sock_in, int *sock_out) 956 { 957 if (rexeced_flag) { 958 close(REEXEC_CONFIG_PASS_FD); 959 *sock_in = *sock_out = dup(STDIN_FILENO); 960 } else { 961 *sock_in = dup(STDIN_FILENO); 962 *sock_out = dup(STDOUT_FILENO); 963 } 964 /* 965 * We intentionally do not close the descriptors 0, 1, and 2 966 * as our code for setting the descriptors won't work if 967 * ttyfd happens to be one of those. 968 */ 969 if (stdfd_devnull(1, 1, !log_stderr) == -1) 970 error_f("stdfd_devnull failed"); 971 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 972 } 973 974 /* 975 * Listen for TCP connections 976 */ 977 static void 978 listen_on_addrs(struct listenaddr *la) 979 { 980 int ret, listen_sock; 981 struct addrinfo *ai; 982 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 983 984 for (ai = la->addrs; ai; ai = ai->ai_next) { 985 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 986 continue; 987 if (num_listen_socks >= MAX_LISTEN_SOCKS) 988 fatal("Too many listen sockets. " 989 "Enlarge MAX_LISTEN_SOCKS"); 990 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 991 ntop, sizeof(ntop), strport, sizeof(strport), 992 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 993 error("getnameinfo failed: %.100s", 994 ssh_gai_strerror(ret)); 995 continue; 996 } 997 /* Create socket for listening. */ 998 listen_sock = socket(ai->ai_family, ai->ai_socktype, 999 ai->ai_protocol); 1000 if (listen_sock == -1) { 1001 /* kernel may not support ipv6 */ 1002 verbose("socket: %.100s", strerror(errno)); 1003 continue; 1004 } 1005 if (set_nonblock(listen_sock) == -1) { 1006 close(listen_sock); 1007 continue; 1008 } 1009 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1010 verbose("socket: CLOEXEC: %s", strerror(errno)); 1011 close(listen_sock); 1012 continue; 1013 } 1014 /* Socket options */ 1015 set_reuseaddr(listen_sock); 1016 if (la->rdomain != NULL && 1017 set_rdomain(listen_sock, la->rdomain) == -1) { 1018 close(listen_sock); 1019 continue; 1020 } 1021 1022 debug("Bind to port %s on %s.", strport, ntop); 1023 1024 /* Bind the socket to the desired port. */ 1025 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1026 error("Bind to port %s on %s failed: %.200s.", 1027 strport, ntop, strerror(errno)); 1028 close(listen_sock); 1029 continue; 1030 } 1031 listen_socks[num_listen_socks] = listen_sock; 1032 num_listen_socks++; 1033 1034 /* Start listening on the port. */ 1035 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1036 fatal("listen on [%s]:%s: %.100s", 1037 ntop, strport, strerror(errno)); 1038 logit("Server listening on %s port %s%s%s.", 1039 ntop, strport, 1040 la->rdomain == NULL ? "" : " rdomain ", 1041 la->rdomain == NULL ? "" : la->rdomain); 1042 } 1043 } 1044 1045 static void 1046 server_listen(void) 1047 { 1048 u_int i; 1049 1050 /* Initialise per-source limit tracking. */ 1051 srclimit_init(options.max_startups, options.per_source_max_startups, 1052 options.per_source_masklen_ipv4, options.per_source_masklen_ipv6); 1053 1054 for (i = 0; i < options.num_listen_addrs; i++) { 1055 listen_on_addrs(&options.listen_addrs[i]); 1056 freeaddrinfo(options.listen_addrs[i].addrs); 1057 free(options.listen_addrs[i].rdomain); 1058 memset(&options.listen_addrs[i], 0, 1059 sizeof(options.listen_addrs[i])); 1060 } 1061 free(options.listen_addrs); 1062 options.listen_addrs = NULL; 1063 options.num_listen_addrs = 0; 1064 1065 if (!num_listen_socks) 1066 fatal("Cannot bind any address."); 1067 } 1068 1069 /* 1070 * The main TCP accept loop. Note that, for the non-debug case, returns 1071 * from this function are in a forked subprocess. 1072 */ 1073 static void 1074 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1075 { 1076 struct pollfd *pfd = NULL; 1077 int i, j, ret, npfd; 1078 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1079 int startup_p[2] = { -1 , -1 }, *startup_pollfd; 1080 char c = 0; 1081 struct sockaddr_storage from; 1082 socklen_t fromlen; 1083 pid_t pid; 1084 sigset_t nsigset, osigset; 1085 1086 /* setup fd set for accept */ 1087 /* pipes connected to unauthenticated child sshd processes */ 1088 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1089 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1090 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 1091 for (i = 0; i < options.max_startups; i++) 1092 startup_pipes[i] = -1; 1093 1094 /* 1095 * Prepare signal mask that we use to block signals that might set 1096 * received_sigterm or received_sighup, so that we are guaranteed 1097 * to immediately wake up the ppoll if a signal is received after 1098 * the flag is checked. 1099 */ 1100 sigemptyset(&nsigset); 1101 sigaddset(&nsigset, SIGHUP); 1102 sigaddset(&nsigset, SIGCHLD); 1103 sigaddset(&nsigset, SIGTERM); 1104 sigaddset(&nsigset, SIGQUIT); 1105 1106 /* sized for worst-case */ 1107 pfd = xcalloc(num_listen_socks + options.max_startups, 1108 sizeof(struct pollfd)); 1109 1110 /* 1111 * Stay listening for connections until the system crashes or 1112 * the daemon is killed with a signal. 1113 */ 1114 for (;;) { 1115 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 1116 if (received_sigterm) { 1117 logit("Received signal %d; terminating.", 1118 (int) received_sigterm); 1119 close_listen_socks(); 1120 if (options.pid_file != NULL) 1121 unlink(options.pid_file); 1122 exit(received_sigterm == SIGTERM ? 0 : 255); 1123 } 1124 if (ostartups != startups) { 1125 setproctitle("%s [listener] %d of %d-%d startups", 1126 listener_proctitle, startups, 1127 options.max_startups_begin, options.max_startups); 1128 ostartups = startups; 1129 } 1130 if (received_sighup) { 1131 if (!lameduck) { 1132 debug("Received SIGHUP; waiting for children"); 1133 close_listen_socks(); 1134 lameduck = 1; 1135 } 1136 if (listening <= 0) { 1137 sigprocmask(SIG_SETMASK, &osigset, NULL); 1138 sighup_restart(); 1139 } 1140 } 1141 1142 for (i = 0; i < num_listen_socks; i++) { 1143 pfd[i].fd = listen_socks[i]; 1144 pfd[i].events = POLLIN; 1145 } 1146 npfd = num_listen_socks; 1147 for (i = 0; i < options.max_startups; i++) { 1148 startup_pollfd[i] = -1; 1149 if (startup_pipes[i] != -1) { 1150 pfd[npfd].fd = startup_pipes[i]; 1151 pfd[npfd].events = POLLIN; 1152 startup_pollfd[i] = npfd++; 1153 } 1154 } 1155 1156 /* Wait until a connection arrives or a child exits. */ 1157 ret = ppoll(pfd, npfd, NULL, &osigset); 1158 if (ret == -1 && errno != EINTR) { 1159 error("ppoll: %.100s", strerror(errno)); 1160 if (errno == EINVAL) 1161 cleanup_exit(1); /* can't recover */ 1162 } 1163 sigprocmask(SIG_SETMASK, &osigset, NULL); 1164 if (ret == -1) 1165 continue; 1166 1167 for (i = 0; i < options.max_startups; i++) { 1168 if (startup_pipes[i] == -1 || 1169 startup_pollfd[i] == -1 || 1170 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 1171 continue; 1172 switch (read(startup_pipes[i], &c, sizeof(c))) { 1173 case -1: 1174 if (errno == EINTR || errno == EAGAIN) 1175 continue; 1176 if (errno != EPIPE) { 1177 error_f("startup pipe %d (fd=%d): " 1178 "read %s", i, startup_pipes[i], 1179 strerror(errno)); 1180 } 1181 /* FALLTHROUGH */ 1182 case 0: 1183 /* child exited or completed auth */ 1184 close(startup_pipes[i]); 1185 srclimit_done(startup_pipes[i]); 1186 startup_pipes[i] = -1; 1187 startups--; 1188 if (startup_flags[i]) 1189 listening--; 1190 break; 1191 case 1: 1192 /* child has finished preliminaries */ 1193 if (startup_flags[i]) { 1194 listening--; 1195 startup_flags[i] = 0; 1196 } 1197 break; 1198 } 1199 } 1200 for (i = 0; i < num_listen_socks; i++) { 1201 if (!(pfd[i].revents & POLLIN)) 1202 continue; 1203 fromlen = sizeof(from); 1204 *newsock = accept(listen_socks[i], 1205 (struct sockaddr *)&from, &fromlen); 1206 if (*newsock == -1) { 1207 if (errno != EINTR && errno != EWOULDBLOCK && 1208 errno != ECONNABORTED) 1209 error("accept: %.100s", 1210 strerror(errno)); 1211 if (errno == EMFILE || errno == ENFILE) 1212 usleep(100 * 1000); 1213 continue; 1214 } 1215 if (unset_nonblock(*newsock) == -1 || 1216 pipe(startup_p) == -1) { 1217 close(*newsock); 1218 continue; 1219 } 1220 if (drop_connection(*newsock, startups, startup_p[0])) { 1221 close(*newsock); 1222 close(startup_p[0]); 1223 close(startup_p[1]); 1224 continue; 1225 } 1226 1227 if (rexec_flag && socketpair(AF_UNIX, 1228 SOCK_STREAM, 0, config_s) == -1) { 1229 error("reexec socketpair: %s", 1230 strerror(errno)); 1231 close(*newsock); 1232 close(startup_p[0]); 1233 close(startup_p[1]); 1234 continue; 1235 } 1236 1237 for (j = 0; j < options.max_startups; j++) 1238 if (startup_pipes[j] == -1) { 1239 startup_pipes[j] = startup_p[0]; 1240 startups++; 1241 startup_flags[j] = 1; 1242 break; 1243 } 1244 1245 /* 1246 * Got connection. Fork a child to handle it, unless 1247 * we are in debugging mode. 1248 */ 1249 if (debug_flag) { 1250 /* 1251 * In debugging mode. Close the listening 1252 * socket, and start processing the 1253 * connection without forking. 1254 */ 1255 debug("Server will not fork when running in debugging mode."); 1256 close_listen_socks(); 1257 *sock_in = *newsock; 1258 *sock_out = *newsock; 1259 close(startup_p[0]); 1260 close(startup_p[1]); 1261 startup_pipe = -1; 1262 pid = getpid(); 1263 if (rexec_flag) { 1264 send_rexec_state(config_s[0], cfg); 1265 close(config_s[0]); 1266 } 1267 free(pfd); 1268 return; 1269 } 1270 1271 /* 1272 * Normal production daemon. Fork, and have 1273 * the child process the connection. The 1274 * parent continues listening. 1275 */ 1276 listening++; 1277 if ((pid = fork()) == 0) { 1278 /* 1279 * Child. Close the listening and 1280 * max_startup sockets. Start using 1281 * the accepted socket. Reinitialize 1282 * logging (since our pid has changed). 1283 * We return from this function to handle 1284 * the connection. 1285 */ 1286 startup_pipe = startup_p[1]; 1287 close_startup_pipes(); 1288 close_listen_socks(); 1289 *sock_in = *newsock; 1290 *sock_out = *newsock; 1291 log_init(__progname, 1292 options.log_level, 1293 options.log_facility, 1294 log_stderr); 1295 if (rexec_flag) 1296 close(config_s[0]); 1297 else { 1298 /* 1299 * Signal parent that the preliminaries 1300 * for this child are complete. For the 1301 * re-exec case, this happens after the 1302 * child has received the rexec state 1303 * from the server. 1304 */ 1305 (void)atomicio(vwrite, startup_pipe, 1306 "\0", 1); 1307 } 1308 free(pfd); 1309 return; 1310 } 1311 1312 /* Parent. Stay in the loop. */ 1313 if (pid == -1) 1314 error("fork: %.100s", strerror(errno)); 1315 else 1316 debug("Forked child %ld.", (long)pid); 1317 1318 close(startup_p[1]); 1319 1320 if (rexec_flag) { 1321 close(config_s[1]); 1322 send_rexec_state(config_s[0], cfg); 1323 close(config_s[0]); 1324 } 1325 close(*newsock); 1326 } 1327 } 1328 } 1329 1330 /* 1331 * If IP options are supported, make sure there are none (log and 1332 * return an error if any are found). Basically we are worried about 1333 * source routing; it can be used to pretend you are somebody 1334 * (ip-address) you are not. That itself may be "almost acceptable" 1335 * under certain circumstances, but rhosts authentication is useless 1336 * if source routing is accepted. Notice also that if we just dropped 1337 * source routing here, the other side could use IP spoofing to do 1338 * rest of the interaction and could still bypass security. So we 1339 * exit here if we detect any IP options. 1340 */ 1341 static void 1342 check_ip_options(struct ssh *ssh) 1343 { 1344 int sock_in = ssh_packet_get_connection_in(ssh); 1345 struct sockaddr_storage from; 1346 u_char opts[200]; 1347 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1348 char text[sizeof(opts) * 3 + 1]; 1349 1350 memset(&from, 0, sizeof(from)); 1351 if (getpeername(sock_in, (struct sockaddr *)&from, 1352 &fromlen) == -1) 1353 return; 1354 if (from.ss_family != AF_INET) 1355 return; 1356 /* XXX IPv6 options? */ 1357 1358 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1359 &option_size) >= 0 && option_size != 0) { 1360 text[0] = '\0'; 1361 for (i = 0; i < option_size; i++) 1362 snprintf(text + i*3, sizeof(text) - i*3, 1363 " %2.2x", opts[i]); 1364 fatal("Connection from %.100s port %d with IP opts: %.800s", 1365 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1366 } 1367 return; 1368 } 1369 1370 /* Set the routing domain for this process */ 1371 static void 1372 set_process_rdomain(struct ssh *ssh, const char *name) 1373 { 1374 int rtable, ortable = getrtable(); 1375 const char *errstr; 1376 1377 if (name == NULL) 1378 return; /* default */ 1379 1380 if (strcmp(name, "%D") == 0) { 1381 /* "expands" to routing domain of connection */ 1382 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1383 return; 1384 } 1385 1386 rtable = (int)strtonum(name, 0, 255, &errstr); 1387 if (errstr != NULL) /* Shouldn't happen */ 1388 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1389 if (rtable != ortable && setrtable(rtable) != 0) 1390 fatal("Unable to set routing domain %d: %s", 1391 rtable, strerror(errno)); 1392 debug_f("set routing domain %d (was %d)", rtable, ortable); 1393 } 1394 1395 static void 1396 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1397 struct sshkey *key) 1398 { 1399 static struct ssh_digest_ctx *ctx; 1400 u_char *hash; 1401 size_t len; 1402 struct sshbuf *buf; 1403 int r; 1404 1405 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1406 fatal_f("ssh_digest_start"); 1407 if (key == NULL) { /* finalize */ 1408 /* add server config in case we are using agent for host keys */ 1409 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1410 sshbuf_len(server_cfg)) != 0) 1411 fatal_f("ssh_digest_update"); 1412 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1413 hash = xmalloc(len); 1414 if (ssh_digest_final(ctx, hash, len) != 0) 1415 fatal_f("ssh_digest_final"); 1416 options.timing_secret = PEEK_U64(hash); 1417 freezero(hash, len); 1418 ssh_digest_free(ctx); 1419 ctx = NULL; 1420 return; 1421 } 1422 if ((buf = sshbuf_new()) == NULL) 1423 fatal_f("could not allocate buffer"); 1424 if ((r = sshkey_private_serialize(key, buf)) != 0) 1425 fatal_fr(r, "decode key"); 1426 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1427 fatal_f("ssh_digest_update"); 1428 sshbuf_reset(buf); 1429 sshbuf_free(buf); 1430 } 1431 1432 static char * 1433 prepare_proctitle(int ac, char **av) 1434 { 1435 char *ret = NULL; 1436 int i; 1437 1438 for (i = 0; i < ac; i++) 1439 xextendf(&ret, " ", "%s", av[i]); 1440 return ret; 1441 } 1442 1443 /* 1444 * Main program for the daemon. 1445 */ 1446 int 1447 main(int ac, char **av) 1448 { 1449 struct ssh *ssh = NULL; 1450 extern char *optarg; 1451 extern int optind; 1452 int r, opt, on = 1, already_daemon, remote_port; 1453 int sock_in = -1, sock_out = -1, newsock = -1; 1454 const char *remote_ip, *rdomain; 1455 char *fp, *line, *laddr, *logfile = NULL; 1456 int config_s[2] = { -1 , -1 }; 1457 u_int i, j; 1458 u_int64_t ibytes, obytes; 1459 mode_t new_umask; 1460 struct sshkey *key; 1461 struct sshkey *pubkey; 1462 int keytype; 1463 Authctxt *authctxt; 1464 struct connection_info *connection_info = NULL; 1465 1466 /* Save argv. */ 1467 saved_argv = av; 1468 rexec_argc = ac; 1469 1470 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1471 sanitise_stdfd(); 1472 1473 /* Initialize configuration options to their default values. */ 1474 initialize_server_options(&options); 1475 1476 /* Parse command-line arguments. */ 1477 while ((opt = getopt(ac, av, 1478 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1479 switch (opt) { 1480 case '4': 1481 options.address_family = AF_INET; 1482 break; 1483 case '6': 1484 options.address_family = AF_INET6; 1485 break; 1486 case 'f': 1487 config_file_name = optarg; 1488 break; 1489 case 'c': 1490 servconf_add_hostcert("[command-line]", 0, 1491 &options, optarg); 1492 break; 1493 case 'd': 1494 if (debug_flag == 0) { 1495 debug_flag = 1; 1496 options.log_level = SYSLOG_LEVEL_DEBUG1; 1497 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1498 options.log_level++; 1499 break; 1500 case 'D': 1501 no_daemon_flag = 1; 1502 break; 1503 case 'E': 1504 logfile = optarg; 1505 /* FALLTHROUGH */ 1506 case 'e': 1507 log_stderr = 1; 1508 break; 1509 case 'i': 1510 inetd_flag = 1; 1511 break; 1512 case 'r': 1513 rexec_flag = 0; 1514 break; 1515 case 'R': 1516 rexeced_flag = 1; 1517 inetd_flag = 1; 1518 break; 1519 case 'Q': 1520 /* ignored */ 1521 break; 1522 case 'q': 1523 options.log_level = SYSLOG_LEVEL_QUIET; 1524 break; 1525 case 'b': 1526 /* protocol 1, ignored */ 1527 break; 1528 case 'p': 1529 options.ports_from_cmdline = 1; 1530 if (options.num_ports >= MAX_PORTS) { 1531 fprintf(stderr, "too many ports.\n"); 1532 exit(1); 1533 } 1534 options.ports[options.num_ports++] = a2port(optarg); 1535 if (options.ports[options.num_ports-1] <= 0) { 1536 fprintf(stderr, "Bad port number.\n"); 1537 exit(1); 1538 } 1539 break; 1540 case 'g': 1541 if ((options.login_grace_time = convtime(optarg)) == -1) { 1542 fprintf(stderr, "Invalid login grace time.\n"); 1543 exit(1); 1544 } 1545 break; 1546 case 'k': 1547 /* protocol 1, ignored */ 1548 break; 1549 case 'h': 1550 servconf_add_hostkey("[command-line]", 0, 1551 &options, optarg, 1); 1552 break; 1553 case 't': 1554 test_flag = 1; 1555 break; 1556 case 'T': 1557 test_flag = 2; 1558 break; 1559 case 'C': 1560 connection_info = get_connection_info(ssh, 0, 0); 1561 if (parse_server_match_testspec(connection_info, 1562 optarg) == -1) 1563 exit(1); 1564 break; 1565 case 'u': 1566 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1567 if (utmp_len > HOST_NAME_MAX+1) { 1568 fprintf(stderr, "Invalid utmp length.\n"); 1569 exit(1); 1570 } 1571 break; 1572 case 'o': 1573 line = xstrdup(optarg); 1574 if (process_server_config_line(&options, line, 1575 "command-line", 0, NULL, NULL, &includes) != 0) 1576 exit(1); 1577 free(line); 1578 break; 1579 case '?': 1580 default: 1581 usage(); 1582 break; 1583 } 1584 } 1585 if (rexeced_flag || inetd_flag) 1586 rexec_flag = 0; 1587 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1588 fatal("sshd re-exec requires execution with an absolute path"); 1589 if (rexeced_flag) 1590 closefrom(REEXEC_MIN_FREE_FD); 1591 else 1592 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1593 1594 #ifdef WITH_OPENSSL 1595 OpenSSL_add_all_algorithms(); 1596 #endif 1597 1598 /* If requested, redirect the logs to the specified logfile. */ 1599 if (logfile != NULL) 1600 log_redirect_stderr_to(logfile); 1601 /* 1602 * Force logging to stderr until we have loaded the private host 1603 * key (unless started from inetd) 1604 */ 1605 log_init(__progname, 1606 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1607 SYSLOG_LEVEL_INFO : options.log_level, 1608 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1609 SYSLOG_FACILITY_AUTH : options.log_facility, 1610 log_stderr || !inetd_flag || debug_flag); 1611 1612 sensitive_data.have_ssh2_key = 0; 1613 1614 /* 1615 * If we're not doing an extended test do not silently ignore connection 1616 * test params. 1617 */ 1618 if (test_flag < 2 && connection_info != NULL) 1619 fatal("Config test connection parameter (-C) provided without " 1620 "test mode (-T)"); 1621 1622 /* Fetch our configuration */ 1623 if ((cfg = sshbuf_new()) == NULL) 1624 fatal_f("sshbuf_new failed"); 1625 if (rexeced_flag) { 1626 setproctitle("%s", "[rexeced]"); 1627 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1628 if (!debug_flag) { 1629 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1630 close(REEXEC_STARTUP_PIPE_FD); 1631 /* 1632 * Signal parent that this child is at a point where 1633 * they can go away if they have a SIGHUP pending. 1634 */ 1635 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1636 } 1637 } else if (strcasecmp(config_file_name, "none") != 0) 1638 load_server_config(config_file_name, cfg); 1639 1640 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1641 cfg, &includes, NULL, rexeced_flag); 1642 1643 #ifdef WITH_OPENSSL 1644 if (options.moduli_file != NULL) 1645 dh_set_moduli_file(options.moduli_file); 1646 #endif 1647 1648 /* Fill in default values for those options not explicitly set. */ 1649 fill_default_server_options(&options); 1650 1651 /* Check that options are sensible */ 1652 if (options.authorized_keys_command_user == NULL && 1653 (options.authorized_keys_command != NULL && 1654 strcasecmp(options.authorized_keys_command, "none") != 0)) 1655 fatal("AuthorizedKeysCommand set without " 1656 "AuthorizedKeysCommandUser"); 1657 if (options.authorized_principals_command_user == NULL && 1658 (options.authorized_principals_command != NULL && 1659 strcasecmp(options.authorized_principals_command, "none") != 0)) 1660 fatal("AuthorizedPrincipalsCommand set without " 1661 "AuthorizedPrincipalsCommandUser"); 1662 1663 /* 1664 * Check whether there is any path through configured auth methods. 1665 * Unfortunately it is not possible to verify this generally before 1666 * daemonisation in the presence of Match block, but this catches 1667 * and warns for trivial misconfigurations that could break login. 1668 */ 1669 if (options.num_auth_methods != 0) { 1670 for (i = 0; i < options.num_auth_methods; i++) { 1671 if (auth2_methods_valid(options.auth_methods[i], 1672 1) == 0) 1673 break; 1674 } 1675 if (i >= options.num_auth_methods) 1676 fatal("AuthenticationMethods cannot be satisfied by " 1677 "enabled authentication methods"); 1678 } 1679 1680 /* Check that there are no remaining arguments. */ 1681 if (optind < ac) { 1682 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1683 exit(1); 1684 } 1685 1686 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1687 1688 /* load host keys */ 1689 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1690 sizeof(struct sshkey *)); 1691 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1692 sizeof(struct sshkey *)); 1693 1694 if (options.host_key_agent) { 1695 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1696 setenv(SSH_AUTHSOCKET_ENV_NAME, 1697 options.host_key_agent, 1); 1698 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1699 have_agent = 1; 1700 else 1701 error_r(r, "Could not connect to agent \"%s\"", 1702 options.host_key_agent); 1703 } 1704 1705 for (i = 0; i < options.num_host_key_files; i++) { 1706 int ll = options.host_key_file_userprovided[i] ? 1707 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1708 1709 if (options.host_key_files[i] == NULL) 1710 continue; 1711 if ((r = sshkey_load_private(options.host_key_files[i], "", 1712 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1713 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1714 options.host_key_files[i]); 1715 if (sshkey_is_sk(key) && 1716 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1717 debug("host key %s requires user presence, ignoring", 1718 options.host_key_files[i]); 1719 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1720 } 1721 if (r == 0 && key != NULL && 1722 (r = sshkey_shield_private(key)) != 0) { 1723 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1724 options.host_key_files[i]); 1725 sshkey_free(key); 1726 key = NULL; 1727 } 1728 if ((r = sshkey_load_public(options.host_key_files[i], 1729 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1730 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1731 options.host_key_files[i]); 1732 if (pubkey != NULL && key != NULL) { 1733 if (!sshkey_equal(pubkey, key)) { 1734 error("Public key for %s does not match " 1735 "private key", options.host_key_files[i]); 1736 sshkey_free(pubkey); 1737 pubkey = NULL; 1738 } 1739 } 1740 if (pubkey == NULL && key != NULL) { 1741 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1742 fatal_r(r, "Could not demote key: \"%s\"", 1743 options.host_key_files[i]); 1744 } 1745 sensitive_data.host_keys[i] = key; 1746 sensitive_data.host_pubkeys[i] = pubkey; 1747 1748 if (key == NULL && pubkey != NULL && have_agent) { 1749 debug("will rely on agent for hostkey %s", 1750 options.host_key_files[i]); 1751 keytype = pubkey->type; 1752 } else if (key != NULL) { 1753 keytype = key->type; 1754 accumulate_host_timing_secret(cfg, key); 1755 } else { 1756 do_log2(ll, "Unable to load host key: %s", 1757 options.host_key_files[i]); 1758 sensitive_data.host_keys[i] = NULL; 1759 sensitive_data.host_pubkeys[i] = NULL; 1760 continue; 1761 } 1762 1763 switch (keytype) { 1764 case KEY_RSA: 1765 case KEY_DSA: 1766 case KEY_ECDSA: 1767 case KEY_ED25519: 1768 case KEY_ECDSA_SK: 1769 case KEY_ED25519_SK: 1770 case KEY_XMSS: 1771 if (have_agent || key != NULL) 1772 sensitive_data.have_ssh2_key = 1; 1773 break; 1774 } 1775 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1776 SSH_FP_DEFAULT)) == NULL) 1777 fatal("sshkey_fingerprint failed"); 1778 debug("%s host key #%d: %s %s", 1779 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1780 free(fp); 1781 } 1782 accumulate_host_timing_secret(cfg, NULL); 1783 if (!sensitive_data.have_ssh2_key) { 1784 logit("sshd: no hostkeys available -- exiting."); 1785 exit(1); 1786 } 1787 1788 /* 1789 * Load certificates. They are stored in an array at identical 1790 * indices to the public keys that they relate to. 1791 */ 1792 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1793 sizeof(struct sshkey *)); 1794 for (i = 0; i < options.num_host_key_files; i++) 1795 sensitive_data.host_certificates[i] = NULL; 1796 1797 for (i = 0; i < options.num_host_cert_files; i++) { 1798 if (options.host_cert_files[i] == NULL) 1799 continue; 1800 if ((r = sshkey_load_public(options.host_cert_files[i], 1801 &key, NULL)) != 0) { 1802 error_r(r, "Could not load host certificate \"%s\"", 1803 options.host_cert_files[i]); 1804 continue; 1805 } 1806 if (!sshkey_is_cert(key)) { 1807 error("Certificate file is not a certificate: %s", 1808 options.host_cert_files[i]); 1809 sshkey_free(key); 1810 continue; 1811 } 1812 /* Find matching private key */ 1813 for (j = 0; j < options.num_host_key_files; j++) { 1814 if (sshkey_equal_public(key, 1815 sensitive_data.host_pubkeys[j])) { 1816 sensitive_data.host_certificates[j] = key; 1817 break; 1818 } 1819 } 1820 if (j >= options.num_host_key_files) { 1821 error("No matching private key for certificate: %s", 1822 options.host_cert_files[i]); 1823 sshkey_free(key); 1824 continue; 1825 } 1826 sensitive_data.host_certificates[j] = key; 1827 debug("host certificate: #%u type %d %s", j, key->type, 1828 sshkey_type(key)); 1829 } 1830 1831 if (use_privsep) { 1832 struct stat st; 1833 1834 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1835 fatal("Privilege separation user %s does not exist", 1836 SSH_PRIVSEP_USER); 1837 endpwent(); 1838 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1839 (S_ISDIR(st.st_mode) == 0)) 1840 fatal("Missing privilege separation directory: %s", 1841 _PATH_PRIVSEP_CHROOT_DIR); 1842 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1843 fatal("%s must be owned by root and not group or " 1844 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1845 } 1846 1847 if (test_flag > 1) { 1848 /* 1849 * If no connection info was provided by -C then use 1850 * use a blank one that will cause no predicate to match. 1851 */ 1852 if (connection_info == NULL) 1853 connection_info = get_connection_info(ssh, 0, 0); 1854 connection_info->test = 1; 1855 parse_server_match_config(&options, &includes, connection_info); 1856 dump_config(&options); 1857 } 1858 1859 /* Configuration looks good, so exit if in test mode. */ 1860 if (test_flag) 1861 exit(0); 1862 1863 if (rexec_flag) { 1864 if (rexec_argc < 0) 1865 fatal("rexec_argc %d < 0", rexec_argc); 1866 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1867 for (i = 0; i < (u_int)rexec_argc; i++) { 1868 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1869 rexec_argv[i] = saved_argv[i]; 1870 } 1871 rexec_argv[rexec_argc] = "-R"; 1872 rexec_argv[rexec_argc + 1] = NULL; 1873 } 1874 listener_proctitle = prepare_proctitle(ac, av); 1875 1876 /* Ensure that umask disallows at least group and world write */ 1877 new_umask = umask(0077) | 0022; 1878 (void) umask(new_umask); 1879 1880 /* Initialize the log (it is reinitialized below in case we forked). */ 1881 if (debug_flag && (!inetd_flag || rexeced_flag)) 1882 log_stderr = 1; 1883 log_init(__progname, options.log_level, 1884 options.log_facility, log_stderr); 1885 for (i = 0; i < options.num_log_verbose; i++) 1886 log_verbose_add(options.log_verbose[i]); 1887 1888 /* 1889 * If not in debugging mode, not started from inetd and not already 1890 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1891 * terminal, and fork. The original process exits. 1892 */ 1893 already_daemon = daemonized(); 1894 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1895 1896 if (daemon(0, 0) == -1) 1897 fatal("daemon() failed: %.200s", strerror(errno)); 1898 1899 disconnect_controlling_tty(); 1900 } 1901 /* Reinitialize the log (because of the fork above). */ 1902 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1903 1904 /* 1905 * Chdir to the root directory so that the current disk can be 1906 * unmounted if desired. 1907 */ 1908 if (chdir("/") == -1) 1909 error("chdir(\"/\"): %s", strerror(errno)); 1910 1911 /* ignore SIGPIPE */ 1912 ssh_signal(SIGPIPE, SIG_IGN); 1913 1914 /* Get a connection, either from inetd or a listening TCP socket */ 1915 if (inetd_flag) { 1916 server_accept_inetd(&sock_in, &sock_out); 1917 } else { 1918 server_listen(); 1919 1920 ssh_signal(SIGHUP, sighup_handler); 1921 ssh_signal(SIGCHLD, main_sigchld_handler); 1922 ssh_signal(SIGTERM, sigterm_handler); 1923 ssh_signal(SIGQUIT, sigterm_handler); 1924 1925 /* 1926 * Write out the pid file after the sigterm handler 1927 * is setup and the listen sockets are bound 1928 */ 1929 if (options.pid_file != NULL && !debug_flag) { 1930 FILE *f = fopen(options.pid_file, "w"); 1931 1932 if (f == NULL) { 1933 error("Couldn't create pid file \"%s\": %s", 1934 options.pid_file, strerror(errno)); 1935 } else { 1936 fprintf(f, "%ld\n", (long) getpid()); 1937 fclose(f); 1938 } 1939 } 1940 1941 /* Accept a connection and return in a forked child */ 1942 server_accept_loop(&sock_in, &sock_out, 1943 &newsock, config_s); 1944 } 1945 1946 /* This is the child processing a new connection. */ 1947 setproctitle("%s", "[accepted]"); 1948 1949 /* 1950 * Create a new session and process group since the 4.4BSD 1951 * setlogin() affects the entire process group. We don't 1952 * want the child to be able to affect the parent. 1953 */ 1954 if (!debug_flag && !inetd_flag && setsid() == -1) 1955 error("setsid: %.100s", strerror(errno)); 1956 1957 if (rexec_flag) { 1958 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1959 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1960 dup2(newsock, STDIN_FILENO); 1961 dup2(STDIN_FILENO, STDOUT_FILENO); 1962 if (startup_pipe == -1) 1963 close(REEXEC_STARTUP_PIPE_FD); 1964 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1965 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1966 close(startup_pipe); 1967 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1968 } 1969 1970 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1971 close(config_s[1]); 1972 1973 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1974 execv(rexec_argv[0], rexec_argv); 1975 1976 /* Reexec has failed, fall back and continue */ 1977 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1978 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1979 log_init(__progname, options.log_level, 1980 options.log_facility, log_stderr); 1981 1982 /* Clean up fds */ 1983 close(REEXEC_CONFIG_PASS_FD); 1984 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1985 if (stdfd_devnull(1, 1, 0) == -1) 1986 error_f("stdfd_devnull failed"); 1987 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1988 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1989 } 1990 1991 /* Executed child processes don't need these. */ 1992 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1993 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1994 1995 /* We will not restart on SIGHUP since it no longer makes sense. */ 1996 ssh_signal(SIGALRM, SIG_DFL); 1997 ssh_signal(SIGHUP, SIG_DFL); 1998 ssh_signal(SIGTERM, SIG_DFL); 1999 ssh_signal(SIGQUIT, SIG_DFL); 2000 ssh_signal(SIGCHLD, SIG_DFL); 2001 2002 /* 2003 * Register our connection. This turns encryption off because we do 2004 * not have a key. 2005 */ 2006 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2007 fatal("Unable to create connection"); 2008 the_active_state = ssh; 2009 ssh_packet_set_server(ssh); 2010 2011 check_ip_options(ssh); 2012 2013 /* Prepare the channels layer */ 2014 channel_init_channels(ssh); 2015 channel_set_af(ssh, options.address_family); 2016 process_permitopen(ssh, &options); 2017 2018 /* Set SO_KEEPALIVE if requested. */ 2019 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2020 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2021 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2022 2023 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2024 debug("ssh_remote_port failed"); 2025 cleanup_exit(255); 2026 } 2027 2028 /* 2029 * The rest of the code depends on the fact that 2030 * ssh_remote_ipaddr() caches the remote ip, even if 2031 * the socket goes away. 2032 */ 2033 remote_ip = ssh_remote_ipaddr(ssh); 2034 2035 rdomain = ssh_packet_rdomain_in(ssh); 2036 2037 /* Log the connection. */ 2038 laddr = get_local_ipaddr(sock_in); 2039 verbose("Connection from %s port %d on %s port %d%s%s%s", 2040 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2041 rdomain == NULL ? "" : " rdomain \"", 2042 rdomain == NULL ? "" : rdomain, 2043 rdomain == NULL ? "" : "\""); 2044 free(laddr); 2045 2046 /* 2047 * We don't want to listen forever unless the other side 2048 * successfully authenticates itself. So we set up an alarm which is 2049 * cleared after successful authentication. A limit of zero 2050 * indicates no limit. Note that we don't set the alarm in debugging 2051 * mode; it is just annoying to have the server exit just when you 2052 * are about to discover the bug. 2053 */ 2054 ssh_signal(SIGALRM, grace_alarm_handler); 2055 if (!debug_flag) 2056 alarm(options.login_grace_time); 2057 2058 if ((r = kex_exchange_identification(ssh, -1, 2059 options.version_addendum)) != 0) 2060 sshpkt_fatal(ssh, r, "banner exchange"); 2061 2062 ssh_packet_set_nonblocking(ssh); 2063 2064 /* allocate authentication context */ 2065 authctxt = xcalloc(1, sizeof(*authctxt)); 2066 ssh->authctxt = authctxt; 2067 2068 /* XXX global for cleanup, access from other modules */ 2069 the_authctxt = authctxt; 2070 2071 /* Set default key authentication options */ 2072 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2073 fatal("allocation failed"); 2074 2075 /* prepare buffer to collect messages to display to user after login */ 2076 if ((loginmsg = sshbuf_new()) == NULL) 2077 fatal_f("sshbuf_new failed"); 2078 auth_debug_reset(); 2079 2080 if (use_privsep) { 2081 if (privsep_preauth(ssh) == 1) 2082 goto authenticated; 2083 } else if (have_agent) { 2084 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2085 error_r(r, "Unable to get agent socket"); 2086 have_agent = 0; 2087 } 2088 } 2089 2090 /* perform the key exchange */ 2091 /* authenticate user and start session */ 2092 do_ssh2_kex(ssh); 2093 do_authentication2(ssh); 2094 2095 /* 2096 * If we use privilege separation, the unprivileged child transfers 2097 * the current keystate and exits 2098 */ 2099 if (use_privsep) { 2100 mm_send_keystate(ssh, pmonitor); 2101 ssh_packet_clear_keys(ssh); 2102 exit(0); 2103 } 2104 2105 authenticated: 2106 /* 2107 * Cancel the alarm we set to limit the time taken for 2108 * authentication. 2109 */ 2110 alarm(0); 2111 ssh_signal(SIGALRM, SIG_DFL); 2112 authctxt->authenticated = 1; 2113 if (startup_pipe != -1) { 2114 close(startup_pipe); 2115 startup_pipe = -1; 2116 } 2117 2118 if (options.routing_domain != NULL) 2119 set_process_rdomain(ssh, options.routing_domain); 2120 2121 /* 2122 * In privilege separation, we fork another child and prepare 2123 * file descriptor passing. 2124 */ 2125 if (use_privsep) { 2126 privsep_postauth(ssh, authctxt); 2127 /* the monitor process [priv] will not return */ 2128 } 2129 2130 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2131 options.client_alive_count_max); 2132 2133 /* Try to send all our hostkeys to the client */ 2134 notify_hostkeys(ssh); 2135 2136 /* Start session. */ 2137 do_authenticated(ssh, authctxt); 2138 2139 /* The connection has been terminated. */ 2140 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2141 verbose("Transferred: sent %llu, received %llu bytes", 2142 (unsigned long long)obytes, (unsigned long long)ibytes); 2143 2144 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2145 ssh_packet_close(ssh); 2146 2147 if (use_privsep) 2148 mm_terminate(); 2149 2150 exit(0); 2151 } 2152 2153 int 2154 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2155 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2156 const u_char *data, size_t dlen, const char *alg) 2157 { 2158 int r; 2159 2160 if (use_privsep) { 2161 if (privkey) { 2162 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2163 data, dlen, alg, options.sk_provider, NULL, 2164 ssh->compat) < 0) 2165 fatal_f("privkey sign failed"); 2166 } else { 2167 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2168 data, dlen, alg, options.sk_provider, NULL, 2169 ssh->compat) < 0) 2170 fatal_f("pubkey sign failed"); 2171 } 2172 } else { 2173 if (privkey) { 2174 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2175 alg, options.sk_provider, NULL, ssh->compat) < 0) 2176 fatal_f("privkey sign failed"); 2177 } else { 2178 if ((r = ssh_agent_sign(auth_sock, pubkey, 2179 signature, slenp, data, dlen, alg, 2180 ssh->compat)) != 0) { 2181 fatal_fr(r, "agent sign failed"); 2182 } 2183 } 2184 } 2185 return 0; 2186 } 2187 2188 /* SSH2 key exchange */ 2189 static void 2190 do_ssh2_kex(struct ssh *ssh) 2191 { 2192 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2193 struct kex *kex; 2194 int r; 2195 2196 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh, 2197 options.kex_algorithms); 2198 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(ssh, 2199 options.ciphers); 2200 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(ssh, 2201 options.ciphers); 2202 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2203 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2204 2205 if (options.compression == COMP_NONE) { 2206 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2207 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2208 } 2209 2210 if (options.rekey_limit || options.rekey_interval) 2211 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2212 options.rekey_interval); 2213 2214 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2215 ssh, list_hostkey_types()); 2216 2217 /* start key exchange */ 2218 if ((r = kex_setup(ssh, myproposal)) != 0) 2219 fatal_r(r, "kex_setup"); 2220 kex = ssh->kex; 2221 #ifdef WITH_OPENSSL 2222 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2223 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2224 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2225 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2226 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2227 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2228 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2229 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2230 #endif 2231 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2232 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 2233 kex->load_host_public_key=&get_hostkey_public_by_type; 2234 kex->load_host_private_key=&get_hostkey_private_by_type; 2235 kex->host_key_index=&get_hostkey_index; 2236 kex->sign = sshd_hostkey_sign; 2237 2238 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2239 2240 #ifdef DEBUG_KEXDH 2241 /* send 1st encrypted/maced/compressed message */ 2242 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2243 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2244 (r = sshpkt_send(ssh)) != 0 || 2245 (r = ssh_packet_write_wait(ssh)) != 0) 2246 fatal_fr(r, "send test"); 2247 #endif 2248 debug("KEX done"); 2249 } 2250 2251 /* server specific fatal cleanup */ 2252 void 2253 cleanup_exit(int i) 2254 { 2255 if (the_active_state != NULL && the_authctxt != NULL) { 2256 do_cleanup(the_active_state, the_authctxt); 2257 if (use_privsep && privsep_is_preauth && 2258 pmonitor != NULL && pmonitor->m_pid > 1) { 2259 debug("Killing privsep child %d", pmonitor->m_pid); 2260 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2261 errno != ESRCH) { 2262 error_f("kill(%d): %s", pmonitor->m_pid, 2263 strerror(errno)); 2264 } 2265 } 2266 } 2267 _exit(i); 2268 } 2269