1 /* $OpenBSD: sshd.c,v 1.564 2020/10/18 11:32:02 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include <sys/types.h> 46 #include <sys/ioctl.h> 47 #include <sys/wait.h> 48 #include <sys/tree.h> 49 #include <sys/stat.h> 50 #include <sys/socket.h> 51 #include <sys/time.h> 52 #include <sys/queue.h> 53 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <netdb.h> 57 #include <paths.h> 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <stdarg.h> 64 #include <unistd.h> 65 #include <limits.h> 66 67 #ifdef WITH_OPENSSL 68 #include <openssl/bn.h> 69 #endif 70 71 #include "xmalloc.h" 72 #include "ssh.h" 73 #include "ssh2.h" 74 #include "sshpty.h" 75 #include "packet.h" 76 #include "log.h" 77 #include "sshbuf.h" 78 #include "misc.h" 79 #include "match.h" 80 #include "servconf.h" 81 #include "uidswap.h" 82 #include "compat.h" 83 #include "cipher.h" 84 #include "digest.h" 85 #include "sshkey.h" 86 #include "kex.h" 87 #include "myproposal.h" 88 #include "authfile.h" 89 #include "pathnames.h" 90 #include "atomicio.h" 91 #include "canohost.h" 92 #include "hostfile.h" 93 #include "auth.h" 94 #include "authfd.h" 95 #include "msg.h" 96 #include "dispatch.h" 97 #include "channels.h" 98 #include "session.h" 99 #include "monitor.h" 100 #ifdef GSSAPI 101 #include "ssh-gss.h" 102 #endif 103 #include "monitor_wrap.h" 104 #include "ssh-sandbox.h" 105 #include "auth-options.h" 106 #include "version.h" 107 #include "ssherr.h" 108 #include "sk-api.h" 109 110 /* Re-exec fds */ 111 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 112 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 113 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 114 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 115 116 extern char *__progname; 117 118 /* Server configuration options. */ 119 ServerOptions options; 120 121 /* Name of the server configuration file. */ 122 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 123 124 /* 125 * Debug mode flag. This can be set on the command line. If debug 126 * mode is enabled, extra debugging output will be sent to the system 127 * log, the daemon will not go to background, and will exit after processing 128 * the first connection. 129 */ 130 int debug_flag = 0; 131 132 /* 133 * Indicating that the daemon should only test the configuration and keys. 134 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 135 * configuration, optionally using connection information provided by the 136 * "-C" flag. 137 */ 138 static int test_flag = 0; 139 140 /* Flag indicating that the daemon is being started from inetd. */ 141 static int inetd_flag = 0; 142 143 /* Flag indicating that sshd should not detach and become a daemon. */ 144 static int no_daemon_flag = 0; 145 146 /* debug goes to stderr unless inetd_flag is set */ 147 static int log_stderr = 0; 148 149 /* Saved arguments to main(). */ 150 static char **saved_argv; 151 152 /* re-exec */ 153 static int rexeced_flag = 0; 154 static int rexec_flag = 1; 155 static int rexec_argc = 0; 156 static char **rexec_argv; 157 158 /* 159 * The sockets that the server is listening; this is used in the SIGHUP 160 * signal handler. 161 */ 162 #define MAX_LISTEN_SOCKS 16 163 static int listen_socks[MAX_LISTEN_SOCKS]; 164 static int num_listen_socks = 0; 165 166 /* Daemon's agent connection */ 167 int auth_sock = -1; 168 static int have_agent = 0; 169 170 /* 171 * Any really sensitive data in the application is contained in this 172 * structure. The idea is that this structure could be locked into memory so 173 * that the pages do not get written into swap. However, there are some 174 * problems. The private key contains BIGNUMs, and we do not (in principle) 175 * have access to the internals of them, and locking just the structure is 176 * not very useful. Currently, memory locking is not implemented. 177 */ 178 struct { 179 struct sshkey **host_keys; /* all private host keys */ 180 struct sshkey **host_pubkeys; /* all public host keys */ 181 struct sshkey **host_certificates; /* all public host certificates */ 182 int have_ssh2_key; 183 } sensitive_data; 184 185 /* This is set to true when a signal is received. */ 186 static volatile sig_atomic_t received_sighup = 0; 187 static volatile sig_atomic_t received_sigterm = 0; 188 189 /* session identifier, used by RSA-auth */ 190 u_char session_id[16]; 191 192 /* same for ssh2 */ 193 u_char *session_id2 = NULL; 194 u_int session_id2_len = 0; 195 196 /* record remote hostname or ip */ 197 u_int utmp_len = HOST_NAME_MAX+1; 198 199 /* 200 * startup_pipes/flags are used for tracking children of the listening sshd 201 * process early in their lifespans. This tracking is needed for three things: 202 * 203 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 204 * connections. 205 * 2) Avoiding a race condition for SIGHUP processing, where child processes 206 * may have listen_socks open that could collide with main listener process 207 * after it restarts. 208 * 3) Ensuring that rexec'd sshd processes have received their initial state 209 * from the parent listen process before handling SIGHUP. 210 * 211 * Child processes signal that they have completed closure of the listen_socks 212 * and (if applicable) received their rexec state by sending a char over their 213 * sock. Child processes signal that authentication has completed by closing 214 * the sock (or by exiting). 215 */ 216 static int *startup_pipes = NULL; 217 static int *startup_flags = NULL; /* Indicates child closed listener */ 218 static int startup_pipe = -1; /* in child */ 219 220 /* variables used for privilege separation */ 221 int use_privsep = -1; 222 struct monitor *pmonitor = NULL; 223 int privsep_is_preauth = 1; 224 225 /* global connection state and authentication contexts */ 226 Authctxt *the_authctxt = NULL; 227 struct ssh *the_active_state; 228 229 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 230 struct sshauthopt *auth_opts = NULL; 231 232 /* sshd_config buffer */ 233 struct sshbuf *cfg; 234 235 /* Included files from the configuration file */ 236 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 237 238 /* message to be displayed after login */ 239 struct sshbuf *loginmsg; 240 241 /* Prototypes for various functions defined later in this file. */ 242 void destroy_sensitive_data(void); 243 void demote_sensitive_data(void); 244 static void do_ssh2_kex(struct ssh *); 245 246 static char *listener_proctitle; 247 248 /* 249 * Close all listening sockets 250 */ 251 static void 252 close_listen_socks(void) 253 { 254 int i; 255 256 for (i = 0; i < num_listen_socks; i++) 257 close(listen_socks[i]); 258 num_listen_socks = -1; 259 } 260 261 static void 262 close_startup_pipes(void) 263 { 264 int i; 265 266 if (startup_pipes) 267 for (i = 0; i < options.max_startups; i++) 268 if (startup_pipes[i] != -1) 269 close(startup_pipes[i]); 270 } 271 272 /* 273 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 274 * the effect is to reread the configuration file (and to regenerate 275 * the server key). 276 */ 277 278 /*ARGSUSED*/ 279 static void 280 sighup_handler(int sig) 281 { 282 received_sighup = 1; 283 } 284 285 /* 286 * Called from the main program after receiving SIGHUP. 287 * Restarts the server. 288 */ 289 static void 290 sighup_restart(void) 291 { 292 logit("Received SIGHUP; restarting."); 293 if (options.pid_file != NULL) 294 unlink(options.pid_file); 295 close_listen_socks(); 296 close_startup_pipes(); 297 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 298 execv(saved_argv[0], saved_argv); 299 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 300 strerror(errno)); 301 exit(1); 302 } 303 304 /* 305 * Generic signal handler for terminating signals in the master daemon. 306 */ 307 /*ARGSUSED*/ 308 static void 309 sigterm_handler(int sig) 310 { 311 received_sigterm = sig; 312 } 313 314 /* 315 * SIGCHLD handler. This is called whenever a child dies. This will then 316 * reap any zombies left by exited children. 317 */ 318 /*ARGSUSED*/ 319 static void 320 main_sigchld_handler(int sig) 321 { 322 int save_errno = errno; 323 pid_t pid; 324 int status; 325 326 debug("main_sigchld_handler: %s", strsignal(sig)); 327 328 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 329 (pid == -1 && errno == EINTR)) 330 ; 331 errno = save_errno; 332 } 333 334 /* 335 * Signal handler for the alarm after the login grace period has expired. 336 */ 337 /*ARGSUSED*/ 338 static void 339 grace_alarm_handler(int sig) 340 { 341 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 342 kill(pmonitor->m_pid, SIGALRM); 343 344 /* 345 * Try to kill any processes that we have spawned, E.g. authorized 346 * keys command helpers. 347 */ 348 if (getpgid(0) == getpid()) { 349 ssh_signal(SIGTERM, SIG_IGN); 350 kill(0, SIGTERM); 351 } 352 353 /* XXX pre-format ipaddr/port so we don't need to access active_state */ 354 /* Log error and exit. */ 355 sigdie("Timeout before authentication for %s port %d", 356 ssh_remote_ipaddr(the_active_state), 357 ssh_remote_port(the_active_state)); 358 } 359 360 /* Destroy the host and server keys. They will no longer be needed. */ 361 void 362 destroy_sensitive_data(void) 363 { 364 u_int i; 365 366 for (i = 0; i < options.num_host_key_files; i++) { 367 if (sensitive_data.host_keys[i]) { 368 sshkey_free(sensitive_data.host_keys[i]); 369 sensitive_data.host_keys[i] = NULL; 370 } 371 if (sensitive_data.host_certificates[i]) { 372 sshkey_free(sensitive_data.host_certificates[i]); 373 sensitive_data.host_certificates[i] = NULL; 374 } 375 } 376 } 377 378 /* Demote private to public keys for network child */ 379 void 380 demote_sensitive_data(void) 381 { 382 struct sshkey *tmp; 383 u_int i; 384 int r; 385 386 for (i = 0; i < options.num_host_key_files; i++) { 387 if (sensitive_data.host_keys[i]) { 388 if ((r = sshkey_from_private( 389 sensitive_data.host_keys[i], &tmp)) != 0) 390 fatal_r(r, "could not demote host %s key", 391 sshkey_type(sensitive_data.host_keys[i])); 392 sshkey_free(sensitive_data.host_keys[i]); 393 sensitive_data.host_keys[i] = tmp; 394 } 395 /* Certs do not need demotion */ 396 } 397 } 398 399 static void 400 privsep_preauth_child(void) 401 { 402 gid_t gidset[1]; 403 struct passwd *pw; 404 405 /* Enable challenge-response authentication for privilege separation */ 406 privsep_challenge_enable(); 407 408 #ifdef GSSAPI 409 /* Cache supported mechanism OIDs for later use */ 410 ssh_gssapi_prepare_supported_oids(); 411 #endif 412 413 /* Demote the private keys to public keys. */ 414 demote_sensitive_data(); 415 416 /* Demote the child */ 417 if (getuid() == 0 || geteuid() == 0) { 418 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 419 fatal("Privilege separation user %s does not exist", 420 SSH_PRIVSEP_USER); 421 pw = pwcopy(pw); /* Ensure mutable */ 422 endpwent(); 423 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 424 425 /* Change our root directory */ 426 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 427 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 428 strerror(errno)); 429 if (chdir("/") == -1) 430 fatal("chdir(\"/\"): %s", strerror(errno)); 431 432 /* 433 * Drop our privileges 434 * NB. Can't use setusercontext() after chroot. 435 */ 436 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 437 (u_int)pw->pw_gid); 438 gidset[0] = pw->pw_gid; 439 if (setgroups(1, gidset) == -1) 440 fatal("setgroups: %.100s", strerror(errno)); 441 permanently_set_uid(pw); 442 } 443 } 444 445 static int 446 privsep_preauth(struct ssh *ssh) 447 { 448 int status, r; 449 pid_t pid; 450 struct ssh_sandbox *box = NULL; 451 452 /* Set up unprivileged child process to deal with network data */ 453 pmonitor = monitor_init(); 454 /* Store a pointer to the kex for later rekeying */ 455 pmonitor->m_pkex = &ssh->kex; 456 457 if (use_privsep == PRIVSEP_ON) 458 box = ssh_sandbox_init(); 459 pid = fork(); 460 if (pid == -1) { 461 fatal("fork of unprivileged child failed"); 462 } else if (pid != 0) { 463 debug2("Network child is on pid %ld", (long)pid); 464 465 pmonitor->m_pid = pid; 466 if (have_agent) { 467 r = ssh_get_authentication_socket(&auth_sock); 468 if (r != 0) { 469 error_r(r, "Could not get agent socket"); 470 have_agent = 0; 471 } 472 } 473 if (box != NULL) 474 ssh_sandbox_parent_preauth(box, pid); 475 monitor_child_preauth(ssh, pmonitor); 476 477 /* Wait for the child's exit status */ 478 while (waitpid(pid, &status, 0) == -1) { 479 if (errno == EINTR) 480 continue; 481 pmonitor->m_pid = -1; 482 fatal_f("waitpid: %s", strerror(errno)); 483 } 484 privsep_is_preauth = 0; 485 pmonitor->m_pid = -1; 486 if (WIFEXITED(status)) { 487 if (WEXITSTATUS(status) != 0) 488 fatal_f("preauth child exited with status %d", 489 WEXITSTATUS(status)); 490 } else if (WIFSIGNALED(status)) 491 fatal_f("preauth child terminated by signal %d", 492 WTERMSIG(status)); 493 if (box != NULL) 494 ssh_sandbox_parent_finish(box); 495 return 1; 496 } else { 497 /* child */ 498 close(pmonitor->m_sendfd); 499 close(pmonitor->m_log_recvfd); 500 501 /* Arrange for logging to be sent to the monitor */ 502 set_log_handler(mm_log_handler, pmonitor); 503 504 privsep_preauth_child(); 505 setproctitle("%s", "[net]"); 506 if (box != NULL) 507 ssh_sandbox_child(box); 508 509 return 0; 510 } 511 } 512 513 static void 514 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 515 { 516 if (authctxt->pw->pw_uid == 0) { 517 /* File descriptor passing is broken or root login */ 518 use_privsep = 0; 519 goto skip; 520 } 521 522 /* New socket pair */ 523 monitor_reinit(pmonitor); 524 525 pmonitor->m_pid = fork(); 526 if (pmonitor->m_pid == -1) 527 fatal("fork of unprivileged child failed"); 528 else if (pmonitor->m_pid != 0) { 529 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 530 sshbuf_reset(loginmsg); 531 monitor_clear_keystate(ssh, pmonitor); 532 monitor_child_postauth(ssh, pmonitor); 533 534 /* NEVERREACHED */ 535 exit(0); 536 } 537 538 /* child */ 539 540 close(pmonitor->m_sendfd); 541 pmonitor->m_sendfd = -1; 542 543 /* Demote the private keys to public keys. */ 544 demote_sensitive_data(); 545 546 /* Drop privileges */ 547 do_setusercontext(authctxt->pw); 548 549 skip: 550 /* It is safe now to apply the key state */ 551 monitor_apply_keystate(ssh, pmonitor); 552 553 /* 554 * Tell the packet layer that authentication was successful, since 555 * this information is not part of the key state. 556 */ 557 ssh_packet_set_authenticated(ssh); 558 } 559 560 static void 561 append_hostkey_type(struct sshbuf *b, const char *s) 562 { 563 int r; 564 565 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 566 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 567 return; 568 } 569 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 570 fatal_fr(r, "sshbuf_putf"); 571 } 572 573 static char * 574 list_hostkey_types(void) 575 { 576 struct sshbuf *b; 577 struct sshkey *key; 578 char *ret; 579 u_int i; 580 581 if ((b = sshbuf_new()) == NULL) 582 fatal_f("sshbuf_new failed"); 583 for (i = 0; i < options.num_host_key_files; i++) { 584 key = sensitive_data.host_keys[i]; 585 if (key == NULL) 586 key = sensitive_data.host_pubkeys[i]; 587 if (key == NULL) 588 continue; 589 switch (key->type) { 590 case KEY_RSA: 591 /* for RSA we also support SHA2 signatures */ 592 append_hostkey_type(b, "rsa-sha2-512"); 593 append_hostkey_type(b, "rsa-sha2-256"); 594 /* FALLTHROUGH */ 595 case KEY_DSA: 596 case KEY_ECDSA: 597 case KEY_ED25519: 598 case KEY_ECDSA_SK: 599 case KEY_ED25519_SK: 600 case KEY_XMSS: 601 append_hostkey_type(b, sshkey_ssh_name(key)); 602 break; 603 } 604 /* If the private key has a cert peer, then list that too */ 605 key = sensitive_data.host_certificates[i]; 606 if (key == NULL) 607 continue; 608 switch (key->type) { 609 case KEY_RSA_CERT: 610 /* for RSA we also support SHA2 signatures */ 611 append_hostkey_type(b, 612 "rsa-sha2-512-cert-v01@openssh.com"); 613 append_hostkey_type(b, 614 "rsa-sha2-256-cert-v01@openssh.com"); 615 /* FALLTHROUGH */ 616 case KEY_DSA_CERT: 617 case KEY_ECDSA_CERT: 618 case KEY_ED25519_CERT: 619 case KEY_ECDSA_SK_CERT: 620 case KEY_ED25519_SK_CERT: 621 case KEY_XMSS_CERT: 622 append_hostkey_type(b, sshkey_ssh_name(key)); 623 break; 624 } 625 } 626 if ((ret = sshbuf_dup_string(b)) == NULL) 627 fatal_f("sshbuf_dup_string failed"); 628 sshbuf_free(b); 629 debug_f("%s", ret); 630 return ret; 631 } 632 633 static struct sshkey * 634 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 635 { 636 u_int i; 637 struct sshkey *key; 638 639 for (i = 0; i < options.num_host_key_files; i++) { 640 switch (type) { 641 case KEY_RSA_CERT: 642 case KEY_DSA_CERT: 643 case KEY_ECDSA_CERT: 644 case KEY_ED25519_CERT: 645 case KEY_ECDSA_SK_CERT: 646 case KEY_ED25519_SK_CERT: 647 case KEY_XMSS_CERT: 648 key = sensitive_data.host_certificates[i]; 649 break; 650 default: 651 key = sensitive_data.host_keys[i]; 652 if (key == NULL && !need_private) 653 key = sensitive_data.host_pubkeys[i]; 654 break; 655 } 656 if (key == NULL || key->type != type) 657 continue; 658 switch (type) { 659 case KEY_ECDSA: 660 case KEY_ECDSA_SK: 661 case KEY_ECDSA_CERT: 662 case KEY_ECDSA_SK_CERT: 663 if (key->ecdsa_nid != nid) 664 continue; 665 /* FALLTHROUGH */ 666 default: 667 return need_private ? 668 sensitive_data.host_keys[i] : key; 669 } 670 } 671 return NULL; 672 } 673 674 struct sshkey * 675 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 676 { 677 return get_hostkey_by_type(type, nid, 0, ssh); 678 } 679 680 struct sshkey * 681 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 682 { 683 return get_hostkey_by_type(type, nid, 1, ssh); 684 } 685 686 struct sshkey * 687 get_hostkey_by_index(int ind) 688 { 689 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 690 return (NULL); 691 return (sensitive_data.host_keys[ind]); 692 } 693 694 struct sshkey * 695 get_hostkey_public_by_index(int ind, struct ssh *ssh) 696 { 697 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 698 return (NULL); 699 return (sensitive_data.host_pubkeys[ind]); 700 } 701 702 int 703 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 704 { 705 u_int i; 706 707 for (i = 0; i < options.num_host_key_files; i++) { 708 if (sshkey_is_cert(key)) { 709 if (key == sensitive_data.host_certificates[i] || 710 (compare && sensitive_data.host_certificates[i] && 711 sshkey_equal(key, 712 sensitive_data.host_certificates[i]))) 713 return (i); 714 } else { 715 if (key == sensitive_data.host_keys[i] || 716 (compare && sensitive_data.host_keys[i] && 717 sshkey_equal(key, sensitive_data.host_keys[i]))) 718 return (i); 719 if (key == sensitive_data.host_pubkeys[i] || 720 (compare && sensitive_data.host_pubkeys[i] && 721 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 722 return (i); 723 } 724 } 725 return (-1); 726 } 727 728 /* Inform the client of all hostkeys */ 729 static void 730 notify_hostkeys(struct ssh *ssh) 731 { 732 struct sshbuf *buf; 733 struct sshkey *key; 734 u_int i, nkeys; 735 int r; 736 char *fp; 737 738 /* Some clients cannot cope with the hostkeys message, skip those. */ 739 if (ssh->compat & SSH_BUG_HOSTKEYS) 740 return; 741 742 if ((buf = sshbuf_new()) == NULL) 743 fatal_f("sshbuf_new"); 744 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 745 key = get_hostkey_public_by_index(i, ssh); 746 if (key == NULL || key->type == KEY_UNSPEC || 747 sshkey_is_cert(key)) 748 continue; 749 fp = sshkey_fingerprint(key, options.fingerprint_hash, 750 SSH_FP_DEFAULT); 751 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 752 free(fp); 753 if (nkeys == 0) { 754 /* 755 * Start building the request when we find the 756 * first usable key. 757 */ 758 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 759 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 760 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 761 sshpkt_fatal(ssh, r, "%s: start request", __func__); 762 } 763 /* Append the key to the request */ 764 sshbuf_reset(buf); 765 if ((r = sshkey_putb(key, buf)) != 0) 766 fatal_fr(r, "couldn't put hostkey %d", i); 767 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 768 sshpkt_fatal(ssh, r, "%s: append key", __func__); 769 nkeys++; 770 } 771 debug3_f("sent %u hostkeys", nkeys); 772 if (nkeys == 0) 773 fatal_f("no hostkeys"); 774 if ((r = sshpkt_send(ssh)) != 0) 775 sshpkt_fatal(ssh, r, "%s: send", __func__); 776 sshbuf_free(buf); 777 } 778 779 /* 780 * returns 1 if connection should be dropped, 0 otherwise. 781 * dropping starts at connection #max_startups_begin with a probability 782 * of (max_startups_rate/100). the probability increases linearly until 783 * all connections are dropped for startups > max_startups 784 */ 785 static int 786 should_drop_connection(int startups) 787 { 788 int p, r; 789 790 if (startups < options.max_startups_begin) 791 return 0; 792 if (startups >= options.max_startups) 793 return 1; 794 if (options.max_startups_rate == 100) 795 return 1; 796 797 p = 100 - options.max_startups_rate; 798 p *= startups - options.max_startups_begin; 799 p /= options.max_startups - options.max_startups_begin; 800 p += options.max_startups_rate; 801 r = arc4random_uniform(100); 802 803 debug_f("p %d, r %d", p, r); 804 return (r < p) ? 1 : 0; 805 } 806 807 /* 808 * Check whether connection should be accepted by MaxStartups. 809 * Returns 0 if the connection is accepted. If the connection is refused, 810 * returns 1 and attempts to send notification to client. 811 * Logs when the MaxStartups condition is entered or exited, and periodically 812 * while in that state. 813 */ 814 static int 815 drop_connection(int sock, int startups) 816 { 817 char *laddr, *raddr; 818 const char msg[] = "Exceeded MaxStartups\r\n"; 819 static time_t last_drop, first_drop; 820 static u_int ndropped; 821 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 822 time_t now; 823 824 now = monotime(); 825 if (!should_drop_connection(startups)) { 826 if (last_drop != 0 && 827 startups < options.max_startups_begin - 1) { 828 /* XXX maybe need better hysteresis here */ 829 logit("exited MaxStartups throttling after %s, " 830 "%u connections dropped", 831 fmt_timeframe(now - first_drop), ndropped); 832 last_drop = 0; 833 } 834 return 0; 835 } 836 837 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 838 if (last_drop == 0) { 839 error("beginning MaxStartups throttling"); 840 drop_level = SYSLOG_LEVEL_INFO; 841 first_drop = now; 842 ndropped = 0; 843 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 844 /* Periodic logs */ 845 error("in MaxStartups throttling for %s, " 846 "%u connections dropped", 847 fmt_timeframe(now - first_drop), ndropped + 1); 848 drop_level = SYSLOG_LEVEL_INFO; 849 } 850 last_drop = now; 851 ndropped++; 852 853 laddr = get_local_ipaddr(sock); 854 raddr = get_peer_ipaddr(sock); 855 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 856 "past MaxStartups", startups, raddr, get_peer_port(sock), 857 laddr, get_local_port(sock)); 858 free(laddr); 859 free(raddr); 860 /* best-effort notification to client */ 861 (void)write(sock, msg, sizeof(msg) - 1); 862 return 1; 863 } 864 865 static void 866 usage(void) 867 { 868 fprintf(stderr, "%s, %s\n", 869 SSH_VERSION, 870 #ifdef WITH_OPENSSL 871 OpenSSL_version(OPENSSL_VERSION) 872 #else 873 "without OpenSSL" 874 #endif 875 ); 876 fprintf(stderr, 877 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 878 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 879 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 880 ); 881 exit(1); 882 } 883 884 static void 885 send_rexec_state(int fd, struct sshbuf *conf) 886 { 887 struct sshbuf *m = NULL, *inc = NULL; 888 struct include_item *item = NULL; 889 int r; 890 891 debug3_f("entering fd = %d config len %zu", fd, 892 sshbuf_len(conf)); 893 894 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 895 fatal_f("sshbuf_new failed"); 896 897 /* pack includes into a string */ 898 TAILQ_FOREACH(item, &includes, entry) { 899 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 900 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 901 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 902 fatal_fr(r, "compose includes"); 903 } 904 905 /* 906 * Protocol from reexec master to child: 907 * string configuration 908 * string included_files[] { 909 * string selector 910 * string filename 911 * string contents 912 * } 913 */ 914 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 915 (r = sshbuf_put_stringb(m, inc)) != 0) 916 fatal_fr(r, "compose config"); 917 if (ssh_msg_send(fd, 0, m) == -1) 918 error_f("ssh_msg_send failed"); 919 920 sshbuf_free(m); 921 sshbuf_free(inc); 922 923 debug3_f("done"); 924 } 925 926 static void 927 recv_rexec_state(int fd, struct sshbuf *conf) 928 { 929 struct sshbuf *m, *inc; 930 u_char *cp, ver; 931 size_t len; 932 int r; 933 struct include_item *item; 934 935 debug3_f("entering fd = %d", fd); 936 937 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 938 fatal_f("sshbuf_new failed"); 939 if (ssh_msg_recv(fd, m) == -1) 940 fatal_f("ssh_msg_recv failed"); 941 if ((r = sshbuf_get_u8(m, &ver)) != 0) 942 fatal_fr(r, "parse version"); 943 if (ver != 0) 944 fatal_f("rexec version mismatch"); 945 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 946 (r = sshbuf_get_stringb(m, inc)) != 0) 947 fatal_fr(r, "parse config"); 948 949 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 950 fatal_fr(r, "sshbuf_put"); 951 952 while (sshbuf_len(inc) != 0) { 953 item = xcalloc(1, sizeof(*item)); 954 if ((item->contents = sshbuf_new()) == NULL) 955 fatal_f("sshbuf_new failed"); 956 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 957 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 958 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 959 fatal_fr(r, "parse includes"); 960 TAILQ_INSERT_TAIL(&includes, item, entry); 961 } 962 963 free(cp); 964 sshbuf_free(m); 965 966 debug3_f("done"); 967 } 968 969 /* Accept a connection from inetd */ 970 static void 971 server_accept_inetd(int *sock_in, int *sock_out) 972 { 973 if (rexeced_flag) { 974 close(REEXEC_CONFIG_PASS_FD); 975 *sock_in = *sock_out = dup(STDIN_FILENO); 976 } else { 977 *sock_in = dup(STDIN_FILENO); 978 *sock_out = dup(STDOUT_FILENO); 979 } 980 /* 981 * We intentionally do not close the descriptors 0, 1, and 2 982 * as our code for setting the descriptors won't work if 983 * ttyfd happens to be one of those. 984 */ 985 if (stdfd_devnull(1, 1, !log_stderr) == -1) 986 error_f("stdfd_devnull failed"); 987 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 988 } 989 990 /* 991 * Listen for TCP connections 992 */ 993 static void 994 listen_on_addrs(struct listenaddr *la) 995 { 996 int ret, listen_sock; 997 struct addrinfo *ai; 998 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 999 1000 for (ai = la->addrs; ai; ai = ai->ai_next) { 1001 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1002 continue; 1003 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1004 fatal("Too many listen sockets. " 1005 "Enlarge MAX_LISTEN_SOCKS"); 1006 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1007 ntop, sizeof(ntop), strport, sizeof(strport), 1008 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1009 error("getnameinfo failed: %.100s", 1010 ssh_gai_strerror(ret)); 1011 continue; 1012 } 1013 /* Create socket for listening. */ 1014 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1015 ai->ai_protocol); 1016 if (listen_sock == -1) { 1017 /* kernel may not support ipv6 */ 1018 verbose("socket: %.100s", strerror(errno)); 1019 continue; 1020 } 1021 if (set_nonblock(listen_sock) == -1) { 1022 close(listen_sock); 1023 continue; 1024 } 1025 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1026 verbose("socket: CLOEXEC: %s", strerror(errno)); 1027 close(listen_sock); 1028 continue; 1029 } 1030 /* Socket options */ 1031 set_reuseaddr(listen_sock); 1032 if (la->rdomain != NULL && 1033 set_rdomain(listen_sock, la->rdomain) == -1) { 1034 close(listen_sock); 1035 continue; 1036 } 1037 1038 debug("Bind to port %s on %s.", strport, ntop); 1039 1040 /* Bind the socket to the desired port. */ 1041 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1042 error("Bind to port %s on %s failed: %.200s.", 1043 strport, ntop, strerror(errno)); 1044 close(listen_sock); 1045 continue; 1046 } 1047 listen_socks[num_listen_socks] = listen_sock; 1048 num_listen_socks++; 1049 1050 /* Start listening on the port. */ 1051 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1052 fatal("listen on [%s]:%s: %.100s", 1053 ntop, strport, strerror(errno)); 1054 logit("Server listening on %s port %s%s%s.", 1055 ntop, strport, 1056 la->rdomain == NULL ? "" : " rdomain ", 1057 la->rdomain == NULL ? "" : la->rdomain); 1058 } 1059 } 1060 1061 static void 1062 server_listen(void) 1063 { 1064 u_int i; 1065 1066 for (i = 0; i < options.num_listen_addrs; i++) { 1067 listen_on_addrs(&options.listen_addrs[i]); 1068 freeaddrinfo(options.listen_addrs[i].addrs); 1069 free(options.listen_addrs[i].rdomain); 1070 memset(&options.listen_addrs[i], 0, 1071 sizeof(options.listen_addrs[i])); 1072 } 1073 free(options.listen_addrs); 1074 options.listen_addrs = NULL; 1075 options.num_listen_addrs = 0; 1076 1077 if (!num_listen_socks) 1078 fatal("Cannot bind any address."); 1079 } 1080 1081 /* 1082 * The main TCP accept loop. Note that, for the non-debug case, returns 1083 * from this function are in a forked subprocess. 1084 */ 1085 static void 1086 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1087 { 1088 fd_set *fdset; 1089 int i, j, ret, maxfd; 1090 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1091 int startup_p[2] = { -1 , -1 }; 1092 char c = 0; 1093 struct sockaddr_storage from; 1094 socklen_t fromlen; 1095 pid_t pid; 1096 1097 /* setup fd set for accept */ 1098 fdset = NULL; 1099 maxfd = 0; 1100 for (i = 0; i < num_listen_socks; i++) 1101 if (listen_socks[i] > maxfd) 1102 maxfd = listen_socks[i]; 1103 /* pipes connected to unauthenticated child sshd processes */ 1104 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1105 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1106 for (i = 0; i < options.max_startups; i++) 1107 startup_pipes[i] = -1; 1108 1109 /* 1110 * Stay listening for connections until the system crashes or 1111 * the daemon is killed with a signal. 1112 */ 1113 for (;;) { 1114 if (ostartups != startups) { 1115 setproctitle("%s [listener] %d of %d-%d startups", 1116 listener_proctitle, startups, 1117 options.max_startups_begin, options.max_startups); 1118 ostartups = startups; 1119 } 1120 if (received_sighup) { 1121 if (!lameduck) { 1122 debug("Received SIGHUP; waiting for children"); 1123 close_listen_socks(); 1124 lameduck = 1; 1125 } 1126 if (listening <= 0) 1127 sighup_restart(); 1128 } 1129 free(fdset); 1130 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1131 sizeof(fd_mask)); 1132 1133 for (i = 0; i < num_listen_socks; i++) 1134 FD_SET(listen_socks[i], fdset); 1135 for (i = 0; i < options.max_startups; i++) 1136 if (startup_pipes[i] != -1) 1137 FD_SET(startup_pipes[i], fdset); 1138 1139 /* Wait in select until there is a connection. */ 1140 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1141 if (ret == -1 && errno != EINTR) 1142 error("select: %.100s", strerror(errno)); 1143 if (received_sigterm) { 1144 logit("Received signal %d; terminating.", 1145 (int) received_sigterm); 1146 close_listen_socks(); 1147 if (options.pid_file != NULL) 1148 unlink(options.pid_file); 1149 exit(received_sigterm == SIGTERM ? 0 : 255); 1150 } 1151 if (ret == -1) 1152 continue; 1153 1154 for (i = 0; i < options.max_startups; i++) { 1155 if (startup_pipes[i] == -1 || 1156 !FD_ISSET(startup_pipes[i], fdset)) 1157 continue; 1158 switch (read(startup_pipes[i], &c, sizeof(c))) { 1159 case -1: 1160 if (errno == EINTR || errno == EAGAIN) 1161 continue; 1162 if (errno != EPIPE) { 1163 error_f("startup pipe %d (fd=%d): " 1164 "read %s", i, startup_pipes[i], 1165 strerror(errno)); 1166 } 1167 /* FALLTHROUGH */ 1168 case 0: 1169 /* child exited or completed auth */ 1170 close(startup_pipes[i]); 1171 startup_pipes[i] = -1; 1172 startups--; 1173 if (startup_flags[i]) 1174 listening--; 1175 break; 1176 case 1: 1177 /* child has finished preliminaries */ 1178 if (startup_flags[i]) { 1179 listening--; 1180 startup_flags[i] = 0; 1181 } 1182 break; 1183 } 1184 } 1185 for (i = 0; i < num_listen_socks; i++) { 1186 if (!FD_ISSET(listen_socks[i], fdset)) 1187 continue; 1188 fromlen = sizeof(from); 1189 *newsock = accept(listen_socks[i], 1190 (struct sockaddr *)&from, &fromlen); 1191 if (*newsock == -1) { 1192 if (errno != EINTR && errno != EWOULDBLOCK && 1193 errno != ECONNABORTED) 1194 error("accept: %.100s", 1195 strerror(errno)); 1196 if (errno == EMFILE || errno == ENFILE) 1197 usleep(100 * 1000); 1198 continue; 1199 } 1200 if (unset_nonblock(*newsock) == -1 || 1201 drop_connection(*newsock, startups) || 1202 pipe(startup_p) == -1) { 1203 close(*newsock); 1204 continue; 1205 } 1206 1207 if (rexec_flag && socketpair(AF_UNIX, 1208 SOCK_STREAM, 0, config_s) == -1) { 1209 error("reexec socketpair: %s", 1210 strerror(errno)); 1211 close(*newsock); 1212 close(startup_p[0]); 1213 close(startup_p[1]); 1214 continue; 1215 } 1216 1217 for (j = 0; j < options.max_startups; j++) 1218 if (startup_pipes[j] == -1) { 1219 startup_pipes[j] = startup_p[0]; 1220 if (maxfd < startup_p[0]) 1221 maxfd = startup_p[0]; 1222 startups++; 1223 startup_flags[j] = 1; 1224 break; 1225 } 1226 1227 /* 1228 * Got connection. Fork a child to handle it, unless 1229 * we are in debugging mode. 1230 */ 1231 if (debug_flag) { 1232 /* 1233 * In debugging mode. Close the listening 1234 * socket, and start processing the 1235 * connection without forking. 1236 */ 1237 debug("Server will not fork when running in debugging mode."); 1238 close_listen_socks(); 1239 *sock_in = *newsock; 1240 *sock_out = *newsock; 1241 close(startup_p[0]); 1242 close(startup_p[1]); 1243 startup_pipe = -1; 1244 pid = getpid(); 1245 if (rexec_flag) { 1246 send_rexec_state(config_s[0], cfg); 1247 close(config_s[0]); 1248 } 1249 return; 1250 } 1251 1252 /* 1253 * Normal production daemon. Fork, and have 1254 * the child process the connection. The 1255 * parent continues listening. 1256 */ 1257 listening++; 1258 if ((pid = fork()) == 0) { 1259 /* 1260 * Child. Close the listening and 1261 * max_startup sockets. Start using 1262 * the accepted socket. Reinitialize 1263 * logging (since our pid has changed). 1264 * We return from this function to handle 1265 * the connection. 1266 */ 1267 startup_pipe = startup_p[1]; 1268 close_startup_pipes(); 1269 close_listen_socks(); 1270 *sock_in = *newsock; 1271 *sock_out = *newsock; 1272 log_init(__progname, 1273 options.log_level, 1274 options.log_facility, 1275 log_stderr); 1276 if (rexec_flag) 1277 close(config_s[0]); 1278 else { 1279 /* 1280 * Signal parent that the preliminaries 1281 * for this child are complete. For the 1282 * re-exec case, this happens after the 1283 * child has received the rexec state 1284 * from the server. 1285 */ 1286 (void)atomicio(vwrite, startup_pipe, 1287 "\0", 1); 1288 } 1289 return; 1290 } 1291 1292 /* Parent. Stay in the loop. */ 1293 if (pid == -1) 1294 error("fork: %.100s", strerror(errno)); 1295 else 1296 debug("Forked child %ld.", (long)pid); 1297 1298 close(startup_p[1]); 1299 1300 if (rexec_flag) { 1301 close(config_s[1]); 1302 send_rexec_state(config_s[0], cfg); 1303 close(config_s[0]); 1304 } 1305 close(*newsock); 1306 } 1307 } 1308 } 1309 1310 /* 1311 * If IP options are supported, make sure there are none (log and 1312 * return an error if any are found). Basically we are worried about 1313 * source routing; it can be used to pretend you are somebody 1314 * (ip-address) you are not. That itself may be "almost acceptable" 1315 * under certain circumstances, but rhosts authentication is useless 1316 * if source routing is accepted. Notice also that if we just dropped 1317 * source routing here, the other side could use IP spoofing to do 1318 * rest of the interaction and could still bypass security. So we 1319 * exit here if we detect any IP options. 1320 */ 1321 static void 1322 check_ip_options(struct ssh *ssh) 1323 { 1324 int sock_in = ssh_packet_get_connection_in(ssh); 1325 struct sockaddr_storage from; 1326 u_char opts[200]; 1327 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1328 char text[sizeof(opts) * 3 + 1]; 1329 1330 memset(&from, 0, sizeof(from)); 1331 if (getpeername(sock_in, (struct sockaddr *)&from, 1332 &fromlen) == -1) 1333 return; 1334 if (from.ss_family != AF_INET) 1335 return; 1336 /* XXX IPv6 options? */ 1337 1338 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1339 &option_size) >= 0 && option_size != 0) { 1340 text[0] = '\0'; 1341 for (i = 0; i < option_size; i++) 1342 snprintf(text + i*3, sizeof(text) - i*3, 1343 " %2.2x", opts[i]); 1344 fatal("Connection from %.100s port %d with IP opts: %.800s", 1345 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1346 } 1347 return; 1348 } 1349 1350 /* Set the routing domain for this process */ 1351 static void 1352 set_process_rdomain(struct ssh *ssh, const char *name) 1353 { 1354 int rtable, ortable = getrtable(); 1355 const char *errstr; 1356 1357 if (name == NULL) 1358 return; /* default */ 1359 1360 if (strcmp(name, "%D") == 0) { 1361 /* "expands" to routing domain of connection */ 1362 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1363 return; 1364 } 1365 1366 rtable = (int)strtonum(name, 0, 255, &errstr); 1367 if (errstr != NULL) /* Shouldn't happen */ 1368 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1369 if (rtable != ortable && setrtable(rtable) != 0) 1370 fatal("Unable to set routing domain %d: %s", 1371 rtable, strerror(errno)); 1372 debug_f("set routing domain %d (was %d)", rtable, ortable); 1373 } 1374 1375 static void 1376 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1377 struct sshkey *key) 1378 { 1379 static struct ssh_digest_ctx *ctx; 1380 u_char *hash; 1381 size_t len; 1382 struct sshbuf *buf; 1383 int r; 1384 1385 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1386 fatal_f("ssh_digest_start"); 1387 if (key == NULL) { /* finalize */ 1388 /* add server config in case we are using agent for host keys */ 1389 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1390 sshbuf_len(server_cfg)) != 0) 1391 fatal_f("ssh_digest_update"); 1392 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1393 hash = xmalloc(len); 1394 if (ssh_digest_final(ctx, hash, len) != 0) 1395 fatal_f("ssh_digest_final"); 1396 options.timing_secret = PEEK_U64(hash); 1397 freezero(hash, len); 1398 ssh_digest_free(ctx); 1399 ctx = NULL; 1400 return; 1401 } 1402 if ((buf = sshbuf_new()) == NULL) 1403 fatal_f("could not allocate buffer"); 1404 if ((r = sshkey_private_serialize(key, buf)) != 0) 1405 fatal_fr(r, "decode key"); 1406 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1407 fatal_f("ssh_digest_update"); 1408 sshbuf_reset(buf); 1409 sshbuf_free(buf); 1410 } 1411 1412 static char * 1413 prepare_proctitle(int ac, char **av) 1414 { 1415 char *ret = NULL; 1416 int i; 1417 1418 for (i = 0; i < ac; i++) 1419 xextendf(&ret, " ", "%s", av[i]); 1420 return ret; 1421 } 1422 1423 /* 1424 * Main program for the daemon. 1425 */ 1426 int 1427 main(int ac, char **av) 1428 { 1429 struct ssh *ssh = NULL; 1430 extern char *optarg; 1431 extern int optind; 1432 int r, opt, on = 1, already_daemon, remote_port; 1433 int sock_in = -1, sock_out = -1, newsock = -1; 1434 const char *remote_ip, *rdomain; 1435 char *fp, *line, *laddr, *logfile = NULL; 1436 int config_s[2] = { -1 , -1 }; 1437 u_int i, j; 1438 u_int64_t ibytes, obytes; 1439 mode_t new_umask; 1440 struct sshkey *key; 1441 struct sshkey *pubkey; 1442 int keytype; 1443 Authctxt *authctxt; 1444 struct connection_info *connection_info = NULL; 1445 1446 /* Save argv. */ 1447 saved_argv = av; 1448 rexec_argc = ac; 1449 1450 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1451 sanitise_stdfd(); 1452 1453 /* Initialize configuration options to their default values. */ 1454 initialize_server_options(&options); 1455 1456 /* Parse command-line arguments. */ 1457 while ((opt = getopt(ac, av, 1458 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1459 switch (opt) { 1460 case '4': 1461 options.address_family = AF_INET; 1462 break; 1463 case '6': 1464 options.address_family = AF_INET6; 1465 break; 1466 case 'f': 1467 config_file_name = optarg; 1468 break; 1469 case 'c': 1470 servconf_add_hostcert("[command-line]", 0, 1471 &options, optarg); 1472 break; 1473 case 'd': 1474 if (debug_flag == 0) { 1475 debug_flag = 1; 1476 options.log_level = SYSLOG_LEVEL_DEBUG1; 1477 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1478 options.log_level++; 1479 break; 1480 case 'D': 1481 no_daemon_flag = 1; 1482 break; 1483 case 'E': 1484 logfile = optarg; 1485 /* FALLTHROUGH */ 1486 case 'e': 1487 log_stderr = 1; 1488 break; 1489 case 'i': 1490 inetd_flag = 1; 1491 break; 1492 case 'r': 1493 rexec_flag = 0; 1494 break; 1495 case 'R': 1496 rexeced_flag = 1; 1497 inetd_flag = 1; 1498 break; 1499 case 'Q': 1500 /* ignored */ 1501 break; 1502 case 'q': 1503 options.log_level = SYSLOG_LEVEL_QUIET; 1504 break; 1505 case 'b': 1506 /* protocol 1, ignored */ 1507 break; 1508 case 'p': 1509 options.ports_from_cmdline = 1; 1510 if (options.num_ports >= MAX_PORTS) { 1511 fprintf(stderr, "too many ports.\n"); 1512 exit(1); 1513 } 1514 options.ports[options.num_ports++] = a2port(optarg); 1515 if (options.ports[options.num_ports-1] <= 0) { 1516 fprintf(stderr, "Bad port number.\n"); 1517 exit(1); 1518 } 1519 break; 1520 case 'g': 1521 if ((options.login_grace_time = convtime(optarg)) == -1) { 1522 fprintf(stderr, "Invalid login grace time.\n"); 1523 exit(1); 1524 } 1525 break; 1526 case 'k': 1527 /* protocol 1, ignored */ 1528 break; 1529 case 'h': 1530 servconf_add_hostkey("[command-line]", 0, 1531 &options, optarg, 1); 1532 break; 1533 case 't': 1534 test_flag = 1; 1535 break; 1536 case 'T': 1537 test_flag = 2; 1538 break; 1539 case 'C': 1540 connection_info = get_connection_info(ssh, 0, 0); 1541 if (parse_server_match_testspec(connection_info, 1542 optarg) == -1) 1543 exit(1); 1544 break; 1545 case 'u': 1546 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1547 if (utmp_len > HOST_NAME_MAX+1) { 1548 fprintf(stderr, "Invalid utmp length.\n"); 1549 exit(1); 1550 } 1551 break; 1552 case 'o': 1553 line = xstrdup(optarg); 1554 if (process_server_config_line(&options, line, 1555 "command-line", 0, NULL, NULL, &includes) != 0) 1556 exit(1); 1557 free(line); 1558 break; 1559 case '?': 1560 default: 1561 usage(); 1562 break; 1563 } 1564 } 1565 if (rexeced_flag || inetd_flag) 1566 rexec_flag = 0; 1567 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1568 fatal("sshd re-exec requires execution with an absolute path"); 1569 if (rexeced_flag) 1570 closefrom(REEXEC_MIN_FREE_FD); 1571 else 1572 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1573 1574 #ifdef WITH_OPENSSL 1575 OpenSSL_add_all_algorithms(); 1576 #endif 1577 1578 /* If requested, redirect the logs to the specified logfile. */ 1579 if (logfile != NULL) 1580 log_redirect_stderr_to(logfile); 1581 /* 1582 * Force logging to stderr until we have loaded the private host 1583 * key (unless started from inetd) 1584 */ 1585 log_init(__progname, 1586 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1587 SYSLOG_LEVEL_INFO : options.log_level, 1588 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1589 SYSLOG_FACILITY_AUTH : options.log_facility, 1590 log_stderr || !inetd_flag || debug_flag); 1591 1592 sensitive_data.have_ssh2_key = 0; 1593 1594 /* 1595 * If we're not doing an extended test do not silently ignore connection 1596 * test params. 1597 */ 1598 if (test_flag < 2 && connection_info != NULL) 1599 fatal("Config test connection parameter (-C) provided without " 1600 "test mode (-T)"); 1601 1602 /* Fetch our configuration */ 1603 if ((cfg = sshbuf_new()) == NULL) 1604 fatal_f("sshbuf_new failed"); 1605 if (rexeced_flag) { 1606 setproctitle("%s", "[rexeced]"); 1607 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1608 if (!debug_flag) { 1609 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1610 close(REEXEC_STARTUP_PIPE_FD); 1611 /* 1612 * Signal parent that this child is at a point where 1613 * they can go away if they have a SIGHUP pending. 1614 */ 1615 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1616 } 1617 } else if (strcasecmp(config_file_name, "none") != 0) 1618 load_server_config(config_file_name, cfg); 1619 1620 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1621 cfg, &includes, NULL); 1622 1623 /* Fill in default values for those options not explicitly set. */ 1624 fill_default_server_options(&options); 1625 1626 /* challenge-response is implemented via keyboard interactive */ 1627 if (options.challenge_response_authentication) 1628 options.kbd_interactive_authentication = 1; 1629 1630 /* Check that options are sensible */ 1631 if (options.authorized_keys_command_user == NULL && 1632 (options.authorized_keys_command != NULL && 1633 strcasecmp(options.authorized_keys_command, "none") != 0)) 1634 fatal("AuthorizedKeysCommand set without " 1635 "AuthorizedKeysCommandUser"); 1636 if (options.authorized_principals_command_user == NULL && 1637 (options.authorized_principals_command != NULL && 1638 strcasecmp(options.authorized_principals_command, "none") != 0)) 1639 fatal("AuthorizedPrincipalsCommand set without " 1640 "AuthorizedPrincipalsCommandUser"); 1641 1642 /* 1643 * Check whether there is any path through configured auth methods. 1644 * Unfortunately it is not possible to verify this generally before 1645 * daemonisation in the presence of Match block, but this catches 1646 * and warns for trivial misconfigurations that could break login. 1647 */ 1648 if (options.num_auth_methods != 0) { 1649 for (i = 0; i < options.num_auth_methods; i++) { 1650 if (auth2_methods_valid(options.auth_methods[i], 1651 1) == 0) 1652 break; 1653 } 1654 if (i >= options.num_auth_methods) 1655 fatal("AuthenticationMethods cannot be satisfied by " 1656 "enabled authentication methods"); 1657 } 1658 1659 /* Check that there are no remaining arguments. */ 1660 if (optind < ac) { 1661 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1662 exit(1); 1663 } 1664 1665 debug("sshd version %s, %s", SSH_VERSION, 1666 #ifdef WITH_OPENSSL 1667 OpenSSL_version(OPENSSL_VERSION) 1668 #else 1669 "without OpenSSL" 1670 #endif 1671 ); 1672 1673 /* load host keys */ 1674 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1675 sizeof(struct sshkey *)); 1676 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1677 sizeof(struct sshkey *)); 1678 1679 if (options.host_key_agent) { 1680 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1681 setenv(SSH_AUTHSOCKET_ENV_NAME, 1682 options.host_key_agent, 1); 1683 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1684 have_agent = 1; 1685 else 1686 error_r(r, "Could not connect to agent \"%s\"", 1687 options.host_key_agent); 1688 } 1689 1690 for (i = 0; i < options.num_host_key_files; i++) { 1691 int ll = options.host_key_file_userprovided[i] ? 1692 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1693 1694 if (options.host_key_files[i] == NULL) 1695 continue; 1696 if ((r = sshkey_load_private(options.host_key_files[i], "", 1697 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1698 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1699 options.host_key_files[i]); 1700 if (sshkey_is_sk(key) && 1701 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1702 debug("host key %s requires user presence, ignoring", 1703 options.host_key_files[i]); 1704 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1705 } 1706 if (r == 0 && key != NULL && 1707 (r = sshkey_shield_private(key)) != 0) { 1708 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1709 options.host_key_files[i]); 1710 sshkey_free(key); 1711 key = NULL; 1712 } 1713 if ((r = sshkey_load_public(options.host_key_files[i], 1714 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1715 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1716 options.host_key_files[i]); 1717 if (pubkey != NULL && key != NULL) { 1718 if (!sshkey_equal(pubkey, key)) { 1719 error("Public key for %s does not match " 1720 "private key", options.host_key_files[i]); 1721 sshkey_free(pubkey); 1722 pubkey = NULL; 1723 } 1724 } 1725 if (pubkey == NULL && key != NULL) { 1726 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1727 fatal_r(r, "Could not demote key: \"%s\"", 1728 options.host_key_files[i]); 1729 } 1730 sensitive_data.host_keys[i] = key; 1731 sensitive_data.host_pubkeys[i] = pubkey; 1732 1733 if (key == NULL && pubkey != NULL && have_agent) { 1734 debug("will rely on agent for hostkey %s", 1735 options.host_key_files[i]); 1736 keytype = pubkey->type; 1737 } else if (key != NULL) { 1738 keytype = key->type; 1739 accumulate_host_timing_secret(cfg, key); 1740 } else { 1741 do_log2(ll, "Unable to load host key: %s", 1742 options.host_key_files[i]); 1743 sensitive_data.host_keys[i] = NULL; 1744 sensitive_data.host_pubkeys[i] = NULL; 1745 continue; 1746 } 1747 1748 switch (keytype) { 1749 case KEY_RSA: 1750 case KEY_DSA: 1751 case KEY_ECDSA: 1752 case KEY_ED25519: 1753 case KEY_ECDSA_SK: 1754 case KEY_ED25519_SK: 1755 case KEY_XMSS: 1756 if (have_agent || key != NULL) 1757 sensitive_data.have_ssh2_key = 1; 1758 break; 1759 } 1760 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1761 SSH_FP_DEFAULT)) == NULL) 1762 fatal("sshkey_fingerprint failed"); 1763 debug("%s host key #%d: %s %s", 1764 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1765 free(fp); 1766 } 1767 accumulate_host_timing_secret(cfg, NULL); 1768 if (!sensitive_data.have_ssh2_key) { 1769 logit("sshd: no hostkeys available -- exiting."); 1770 exit(1); 1771 } 1772 1773 /* 1774 * Load certificates. They are stored in an array at identical 1775 * indices to the public keys that they relate to. 1776 */ 1777 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1778 sizeof(struct sshkey *)); 1779 for (i = 0; i < options.num_host_key_files; i++) 1780 sensitive_data.host_certificates[i] = NULL; 1781 1782 for (i = 0; i < options.num_host_cert_files; i++) { 1783 if (options.host_cert_files[i] == NULL) 1784 continue; 1785 if ((r = sshkey_load_public(options.host_cert_files[i], 1786 &key, NULL)) != 0) { 1787 error_r(r, "Could not load host certificate \"%s\"", 1788 options.host_cert_files[i]); 1789 continue; 1790 } 1791 if (!sshkey_is_cert(key)) { 1792 error("Certificate file is not a certificate: %s", 1793 options.host_cert_files[i]); 1794 sshkey_free(key); 1795 continue; 1796 } 1797 /* Find matching private key */ 1798 for (j = 0; j < options.num_host_key_files; j++) { 1799 if (sshkey_equal_public(key, 1800 sensitive_data.host_keys[j])) { 1801 sensitive_data.host_certificates[j] = key; 1802 break; 1803 } 1804 } 1805 if (j >= options.num_host_key_files) { 1806 error("No matching private key for certificate: %s", 1807 options.host_cert_files[i]); 1808 sshkey_free(key); 1809 continue; 1810 } 1811 sensitive_data.host_certificates[j] = key; 1812 debug("host certificate: #%u type %d %s", j, key->type, 1813 sshkey_type(key)); 1814 } 1815 1816 if (use_privsep) { 1817 struct stat st; 1818 1819 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1820 fatal("Privilege separation user %s does not exist", 1821 SSH_PRIVSEP_USER); 1822 endpwent(); 1823 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1824 (S_ISDIR(st.st_mode) == 0)) 1825 fatal("Missing privilege separation directory: %s", 1826 _PATH_PRIVSEP_CHROOT_DIR); 1827 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1828 fatal("%s must be owned by root and not group or " 1829 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1830 } 1831 1832 if (test_flag > 1) { 1833 /* 1834 * If no connection info was provided by -C then use 1835 * use a blank one that will cause no predicate to match. 1836 */ 1837 if (connection_info == NULL) 1838 connection_info = get_connection_info(ssh, 0, 0); 1839 connection_info->test = 1; 1840 parse_server_match_config(&options, &includes, connection_info); 1841 dump_config(&options); 1842 } 1843 1844 /* Configuration looks good, so exit if in test mode. */ 1845 if (test_flag) 1846 exit(0); 1847 1848 if (rexec_flag) { 1849 if (rexec_argc < 0) 1850 fatal("rexec_argc %d < 0", rexec_argc); 1851 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1852 for (i = 0; i < (u_int)rexec_argc; i++) { 1853 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1854 rexec_argv[i] = saved_argv[i]; 1855 } 1856 rexec_argv[rexec_argc] = "-R"; 1857 rexec_argv[rexec_argc + 1] = NULL; 1858 } 1859 listener_proctitle = prepare_proctitle(ac, av); 1860 1861 /* Ensure that umask disallows at least group and world write */ 1862 new_umask = umask(0077) | 0022; 1863 (void) umask(new_umask); 1864 1865 /* Initialize the log (it is reinitialized below in case we forked). */ 1866 if (debug_flag && (!inetd_flag || rexeced_flag)) 1867 log_stderr = 1; 1868 log_init(__progname, options.log_level, 1869 options.log_facility, log_stderr); 1870 for (i = 0; i < options.num_log_verbose; i++) 1871 log_verbose_add(options.log_verbose[i]); 1872 1873 /* 1874 * If not in debugging mode, not started from inetd and not already 1875 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1876 * terminal, and fork. The original process exits. 1877 */ 1878 already_daemon = daemonized(); 1879 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1880 1881 if (daemon(0, 0) == -1) 1882 fatal("daemon() failed: %.200s", strerror(errno)); 1883 1884 disconnect_controlling_tty(); 1885 } 1886 /* Reinitialize the log (because of the fork above). */ 1887 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1888 1889 /* Chdir to the root directory so that the current disk can be 1890 unmounted if desired. */ 1891 if (chdir("/") == -1) 1892 error("chdir(\"/\"): %s", strerror(errno)); 1893 1894 /* ignore SIGPIPE */ 1895 ssh_signal(SIGPIPE, SIG_IGN); 1896 1897 /* Get a connection, either from inetd or a listening TCP socket */ 1898 if (inetd_flag) { 1899 server_accept_inetd(&sock_in, &sock_out); 1900 } else { 1901 server_listen(); 1902 1903 ssh_signal(SIGHUP, sighup_handler); 1904 ssh_signal(SIGCHLD, main_sigchld_handler); 1905 ssh_signal(SIGTERM, sigterm_handler); 1906 ssh_signal(SIGQUIT, sigterm_handler); 1907 1908 /* 1909 * Write out the pid file after the sigterm handler 1910 * is setup and the listen sockets are bound 1911 */ 1912 if (options.pid_file != NULL && !debug_flag) { 1913 FILE *f = fopen(options.pid_file, "w"); 1914 1915 if (f == NULL) { 1916 error("Couldn't create pid file \"%s\": %s", 1917 options.pid_file, strerror(errno)); 1918 } else { 1919 fprintf(f, "%ld\n", (long) getpid()); 1920 fclose(f); 1921 } 1922 } 1923 1924 /* Accept a connection and return in a forked child */ 1925 server_accept_loop(&sock_in, &sock_out, 1926 &newsock, config_s); 1927 } 1928 1929 /* This is the child processing a new connection. */ 1930 setproctitle("%s", "[accepted]"); 1931 1932 /* 1933 * Create a new session and process group since the 4.4BSD 1934 * setlogin() affects the entire process group. We don't 1935 * want the child to be able to affect the parent. 1936 */ 1937 if (!debug_flag && !inetd_flag && setsid() == -1) 1938 error("setsid: %.100s", strerror(errno)); 1939 1940 if (rexec_flag) { 1941 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1942 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1943 dup2(newsock, STDIN_FILENO); 1944 dup2(STDIN_FILENO, STDOUT_FILENO); 1945 if (startup_pipe == -1) 1946 close(REEXEC_STARTUP_PIPE_FD); 1947 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1948 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1949 close(startup_pipe); 1950 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1951 } 1952 1953 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1954 close(config_s[1]); 1955 1956 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1957 execv(rexec_argv[0], rexec_argv); 1958 1959 /* Reexec has failed, fall back and continue */ 1960 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1961 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1962 log_init(__progname, options.log_level, 1963 options.log_facility, log_stderr); 1964 1965 /* Clean up fds */ 1966 close(REEXEC_CONFIG_PASS_FD); 1967 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1968 if (stdfd_devnull(1, 1, 0) == -1) 1969 error_f("stdfd_devnull failed"); 1970 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1971 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1972 } 1973 1974 /* Executed child processes don't need these. */ 1975 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1976 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1977 1978 /* We will not restart on SIGHUP since it no longer makes sense. */ 1979 ssh_signal(SIGALRM, SIG_DFL); 1980 ssh_signal(SIGHUP, SIG_DFL); 1981 ssh_signal(SIGTERM, SIG_DFL); 1982 ssh_signal(SIGQUIT, SIG_DFL); 1983 ssh_signal(SIGCHLD, SIG_DFL); 1984 1985 /* 1986 * Register our connection. This turns encryption off because we do 1987 * not have a key. 1988 */ 1989 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 1990 fatal("Unable to create connection"); 1991 the_active_state = ssh; 1992 ssh_packet_set_server(ssh); 1993 1994 check_ip_options(ssh); 1995 1996 /* Prepare the channels layer */ 1997 channel_init_channels(ssh); 1998 channel_set_af(ssh, options.address_family); 1999 process_permitopen(ssh, &options); 2000 2001 /* Set SO_KEEPALIVE if requested. */ 2002 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2003 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2004 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2005 2006 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2007 debug("ssh_remote_port failed"); 2008 cleanup_exit(255); 2009 } 2010 2011 /* 2012 * The rest of the code depends on the fact that 2013 * ssh_remote_ipaddr() caches the remote ip, even if 2014 * the socket goes away. 2015 */ 2016 remote_ip = ssh_remote_ipaddr(ssh); 2017 2018 rdomain = ssh_packet_rdomain_in(ssh); 2019 2020 /* Log the connection. */ 2021 laddr = get_local_ipaddr(sock_in); 2022 verbose("Connection from %s port %d on %s port %d%s%s%s", 2023 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2024 rdomain == NULL ? "" : " rdomain \"", 2025 rdomain == NULL ? "" : rdomain, 2026 rdomain == NULL ? "" : "\""); 2027 free(laddr); 2028 2029 /* 2030 * We don't want to listen forever unless the other side 2031 * successfully authenticates itself. So we set up an alarm which is 2032 * cleared after successful authentication. A limit of zero 2033 * indicates no limit. Note that we don't set the alarm in debugging 2034 * mode; it is just annoying to have the server exit just when you 2035 * are about to discover the bug. 2036 */ 2037 ssh_signal(SIGALRM, grace_alarm_handler); 2038 if (!debug_flag) 2039 alarm(options.login_grace_time); 2040 2041 if ((r = kex_exchange_identification(ssh, -1, 2042 options.version_addendum)) != 0) 2043 sshpkt_fatal(ssh, r, "banner exchange"); 2044 2045 ssh_packet_set_nonblocking(ssh); 2046 2047 /* allocate authentication context */ 2048 authctxt = xcalloc(1, sizeof(*authctxt)); 2049 ssh->authctxt = authctxt; 2050 2051 /* XXX global for cleanup, access from other modules */ 2052 the_authctxt = authctxt; 2053 2054 /* Set default key authentication options */ 2055 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2056 fatal("allocation failed"); 2057 2058 /* prepare buffer to collect messages to display to user after login */ 2059 if ((loginmsg = sshbuf_new()) == NULL) 2060 fatal_f("sshbuf_new failed"); 2061 auth_debug_reset(); 2062 2063 if (use_privsep) { 2064 if (privsep_preauth(ssh) == 1) 2065 goto authenticated; 2066 } else if (have_agent) { 2067 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2068 error_r(r, "Unable to get agent socket"); 2069 have_agent = 0; 2070 } 2071 } 2072 2073 /* perform the key exchange */ 2074 /* authenticate user and start session */ 2075 do_ssh2_kex(ssh); 2076 do_authentication2(ssh); 2077 2078 /* 2079 * If we use privilege separation, the unprivileged child transfers 2080 * the current keystate and exits 2081 */ 2082 if (use_privsep) { 2083 mm_send_keystate(ssh, pmonitor); 2084 ssh_packet_clear_keys(ssh); 2085 exit(0); 2086 } 2087 2088 authenticated: 2089 /* 2090 * Cancel the alarm we set to limit the time taken for 2091 * authentication. 2092 */ 2093 alarm(0); 2094 ssh_signal(SIGALRM, SIG_DFL); 2095 authctxt->authenticated = 1; 2096 if (startup_pipe != -1) { 2097 close(startup_pipe); 2098 startup_pipe = -1; 2099 } 2100 2101 if (options.routing_domain != NULL) 2102 set_process_rdomain(ssh, options.routing_domain); 2103 2104 /* 2105 * In privilege separation, we fork another child and prepare 2106 * file descriptor passing. 2107 */ 2108 if (use_privsep) { 2109 privsep_postauth(ssh, authctxt); 2110 /* the monitor process [priv] will not return */ 2111 } 2112 2113 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2114 options.client_alive_count_max); 2115 2116 /* Try to send all our hostkeys to the client */ 2117 notify_hostkeys(ssh); 2118 2119 /* Start session. */ 2120 do_authenticated(ssh, authctxt); 2121 2122 /* The connection has been terminated. */ 2123 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2124 verbose("Transferred: sent %llu, received %llu bytes", 2125 (unsigned long long)obytes, (unsigned long long)ibytes); 2126 2127 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2128 ssh_packet_close(ssh); 2129 2130 if (use_privsep) 2131 mm_terminate(); 2132 2133 exit(0); 2134 } 2135 2136 int 2137 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2138 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2139 const u_char *data, size_t dlen, const char *alg) 2140 { 2141 int r; 2142 2143 if (use_privsep) { 2144 if (privkey) { 2145 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2146 data, dlen, alg, options.sk_provider, NULL, 2147 ssh->compat) < 0) 2148 fatal_f("privkey sign failed"); 2149 } else { 2150 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2151 data, dlen, alg, options.sk_provider, NULL, 2152 ssh->compat) < 0) 2153 fatal_f("pubkey sign failed"); 2154 } 2155 } else { 2156 if (privkey) { 2157 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2158 alg, options.sk_provider, NULL, ssh->compat) < 0) 2159 fatal_f("privkey sign failed"); 2160 } else { 2161 if ((r = ssh_agent_sign(auth_sock, pubkey, 2162 signature, slenp, data, dlen, alg, 2163 ssh->compat)) != 0) { 2164 fatal_fr(r, "agent sign failed"); 2165 } 2166 } 2167 } 2168 return 0; 2169 } 2170 2171 /* SSH2 key exchange */ 2172 static void 2173 do_ssh2_kex(struct ssh *ssh) 2174 { 2175 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2176 struct kex *kex; 2177 int r; 2178 2179 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2180 options.kex_algorithms); 2181 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2182 options.ciphers); 2183 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2184 options.ciphers); 2185 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2186 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2187 2188 if (options.compression == COMP_NONE) { 2189 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2190 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2191 } 2192 2193 if (options.rekey_limit || options.rekey_interval) 2194 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2195 options.rekey_interval); 2196 2197 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2198 list_hostkey_types()); 2199 2200 /* start key exchange */ 2201 if ((r = kex_setup(ssh, myproposal)) != 0) 2202 fatal_r(r, "kex_setup"); 2203 kex = ssh->kex; 2204 #ifdef WITH_OPENSSL 2205 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2206 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2207 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2208 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2209 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2210 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2211 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2212 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2213 #endif 2214 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2215 kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server; 2216 kex->load_host_public_key=&get_hostkey_public_by_type; 2217 kex->load_host_private_key=&get_hostkey_private_by_type; 2218 kex->host_key_index=&get_hostkey_index; 2219 kex->sign = sshd_hostkey_sign; 2220 2221 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2222 2223 session_id2 = kex->session_id; 2224 session_id2_len = kex->session_id_len; 2225 2226 #ifdef DEBUG_KEXDH 2227 /* send 1st encrypted/maced/compressed message */ 2228 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2229 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2230 (r = sshpkt_send(ssh)) != 0 || 2231 (r = ssh_packet_write_wait(ssh)) != 0) 2232 fatal_fr(r, "send test"); 2233 #endif 2234 debug("KEX done"); 2235 } 2236 2237 /* server specific fatal cleanup */ 2238 void 2239 cleanup_exit(int i) 2240 { 2241 if (the_active_state != NULL && the_authctxt != NULL) { 2242 do_cleanup(the_active_state, the_authctxt); 2243 if (use_privsep && privsep_is_preauth && 2244 pmonitor != NULL && pmonitor->m_pid > 1) { 2245 debug("Killing privsep child %d", pmonitor->m_pid); 2246 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2247 errno != ESRCH) { 2248 error_f("kill(%d): %s", pmonitor->m_pid, 2249 strerror(errno)); 2250 } 2251 } 2252 } 2253 _exit(i); 2254 } 2255