1 /* $OpenBSD: sshd.c,v 1.533 2019/03/01 02:32:39 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 "includes.h" 46 47 #include <sys/types.h> 48 #include <sys/ioctl.h> 49 #include <sys/socket.h> 50 #ifdef HAVE_SYS_STAT_H 51 # include <sys/stat.h> 52 #endif 53 #ifdef HAVE_SYS_TIME_H 54 # include <sys/time.h> 55 #endif 56 #include "openbsd-compat/sys-tree.h" 57 #include "openbsd-compat/sys-queue.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 #include <limits.h> 75 76 #ifdef WITH_OPENSSL 77 #include <openssl/dh.h> 78 #include <openssl/bn.h> 79 #include <openssl/rand.h> 80 #include "openbsd-compat/openssl-compat.h" 81 #endif 82 83 #ifdef HAVE_SECUREWARE 84 #include <sys/security.h> 85 #include <prot.h> 86 #endif 87 88 #include "xmalloc.h" 89 #include "ssh.h" 90 #include "ssh2.h" 91 #include "sshpty.h" 92 #include "packet.h" 93 #include "log.h" 94 #include "sshbuf.h" 95 #include "misc.h" 96 #include "match.h" 97 #include "servconf.h" 98 #include "uidswap.h" 99 #include "compat.h" 100 #include "cipher.h" 101 #include "digest.h" 102 #include "sshkey.h" 103 #include "kex.h" 104 #include "myproposal.h" 105 #include "authfile.h" 106 #include "pathnames.h" 107 #include "atomicio.h" 108 #include "canohost.h" 109 #include "hostfile.h" 110 #include "auth.h" 111 #include "authfd.h" 112 #include "msg.h" 113 #include "dispatch.h" 114 #include "channels.h" 115 #include "session.h" 116 #include "monitor.h" 117 #ifdef GSSAPI 118 #include "ssh-gss.h" 119 #endif 120 #include "monitor_wrap.h" 121 #include "ssh-sandbox.h" 122 #include "auth-options.h" 123 #include "version.h" 124 #include "ssherr.h" 125 126 /* Re-exec fds */ 127 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 128 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 129 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 130 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 131 132 extern char *__progname; 133 134 /* Server configuration options. */ 135 ServerOptions options; 136 137 /* Name of the server configuration file. */ 138 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 139 140 /* 141 * Debug mode flag. This can be set on the command line. If debug 142 * mode is enabled, extra debugging output will be sent to the system 143 * log, the daemon will not go to background, and will exit after processing 144 * the first connection. 145 */ 146 int debug_flag = 0; 147 148 /* 149 * Indicating that the daemon should only test the configuration and keys. 150 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 151 * configuration, optionally using connection information provided by the 152 * "-C" flag. 153 */ 154 static int test_flag = 0; 155 156 /* Flag indicating that the daemon is being started from inetd. */ 157 static int inetd_flag = 0; 158 159 /* Flag indicating that sshd should not detach and become a daemon. */ 160 static int no_daemon_flag = 0; 161 162 /* debug goes to stderr unless inetd_flag is set */ 163 static int log_stderr = 0; 164 165 /* Saved arguments to main(). */ 166 static char **saved_argv; 167 static int saved_argc; 168 169 /* re-exec */ 170 static int rexeced_flag = 0; 171 static int rexec_flag = 1; 172 static int rexec_argc = 0; 173 static char **rexec_argv; 174 175 /* 176 * The sockets that the server is listening; this is used in the SIGHUP 177 * signal handler. 178 */ 179 #define MAX_LISTEN_SOCKS 16 180 static int listen_socks[MAX_LISTEN_SOCKS]; 181 static int num_listen_socks = 0; 182 183 /* Daemon's agent connection */ 184 int auth_sock = -1; 185 static int have_agent = 0; 186 187 /* 188 * Any really sensitive data in the application is contained in this 189 * structure. The idea is that this structure could be locked into memory so 190 * that the pages do not get written into swap. However, there are some 191 * problems. The private key contains BIGNUMs, and we do not (in principle) 192 * have access to the internals of them, and locking just the structure is 193 * not very useful. Currently, memory locking is not implemented. 194 */ 195 struct { 196 struct sshkey **host_keys; /* all private host keys */ 197 struct sshkey **host_pubkeys; /* all public host keys */ 198 struct sshkey **host_certificates; /* all public host certificates */ 199 int have_ssh2_key; 200 } sensitive_data; 201 202 /* This is set to true when a signal is received. */ 203 static volatile sig_atomic_t received_sighup = 0; 204 static volatile sig_atomic_t received_sigterm = 0; 205 206 /* session identifier, used by RSA-auth */ 207 u_char session_id[16]; 208 209 /* same for ssh2 */ 210 u_char *session_id2 = NULL; 211 u_int session_id2_len = 0; 212 213 /* record remote hostname or ip */ 214 u_int utmp_len = HOST_NAME_MAX+1; 215 216 /* 217 * startup_pipes/flags are used for tracking children of the listening sshd 218 * process early in their lifespans. This tracking is needed for three things: 219 * 220 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 221 * connections. 222 * 2) Avoiding a race condition for SIGHUP processing, where child processes 223 * may have listen_socks open that could collide with main listener process 224 * after it restarts. 225 * 3) Ensuring that rexec'd sshd processes have received their initial state 226 * from the parent listen process before handling SIGHUP. 227 * 228 * Child processes signal that they have completed closure of the listen_socks 229 * and (if applicable) received their rexec state by sending a char over their 230 * sock. Child processes signal that authentication has completed by closing 231 * the sock (or by exiting). 232 */ 233 static int *startup_pipes = NULL; 234 static int *startup_flags = NULL; /* Indicates child closed listener */ 235 static int startup_pipe = -1; /* in child */ 236 237 /* variables used for privilege separation */ 238 int use_privsep = -1; 239 struct monitor *pmonitor = NULL; 240 int privsep_is_preauth = 1; 241 static int privsep_chroot = 1; 242 243 /* global connection state and authentication contexts */ 244 Authctxt *the_authctxt = NULL; 245 struct ssh *the_active_state; 246 247 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 248 struct sshauthopt *auth_opts = NULL; 249 250 /* sshd_config buffer */ 251 struct sshbuf *cfg; 252 253 /* message to be displayed after login */ 254 struct sshbuf *loginmsg; 255 256 /* Unprivileged user */ 257 struct passwd *privsep_pw = NULL; 258 259 /* Prototypes for various functions defined later in this file. */ 260 void destroy_sensitive_data(void); 261 void demote_sensitive_data(void); 262 static void do_ssh2_kex(struct ssh *); 263 264 /* 265 * Close all listening sockets 266 */ 267 static void 268 close_listen_socks(void) 269 { 270 int i; 271 272 for (i = 0; i < num_listen_socks; i++) 273 close(listen_socks[i]); 274 num_listen_socks = -1; 275 } 276 277 static void 278 close_startup_pipes(void) 279 { 280 int i; 281 282 if (startup_pipes) 283 for (i = 0; i < options.max_startups; i++) 284 if (startup_pipes[i] != -1) 285 close(startup_pipes[i]); 286 } 287 288 /* 289 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 290 * the effect is to reread the configuration file (and to regenerate 291 * the server key). 292 */ 293 294 /*ARGSUSED*/ 295 static void 296 sighup_handler(int sig) 297 { 298 int save_errno = errno; 299 300 received_sighup = 1; 301 errno = save_errno; 302 } 303 304 /* 305 * Called from the main program after receiving SIGHUP. 306 * Restarts the server. 307 */ 308 static void 309 sighup_restart(void) 310 { 311 logit("Received SIGHUP; restarting."); 312 if (options.pid_file != NULL) 313 unlink(options.pid_file); 314 platform_pre_restart(); 315 close_listen_socks(); 316 close_startup_pipes(); 317 alarm(0); /* alarm timer persists across exec */ 318 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 319 execv(saved_argv[0], saved_argv); 320 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 321 strerror(errno)); 322 exit(1); 323 } 324 325 /* 326 * Generic signal handler for terminating signals in the master daemon. 327 */ 328 /*ARGSUSED*/ 329 static void 330 sigterm_handler(int sig) 331 { 332 received_sigterm = sig; 333 } 334 335 /* 336 * SIGCHLD handler. This is called whenever a child dies. This will then 337 * reap any zombies left by exited children. 338 */ 339 /*ARGSUSED*/ 340 static void 341 main_sigchld_handler(int sig) 342 { 343 int save_errno = errno; 344 pid_t pid; 345 int status; 346 347 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 348 (pid < 0 && errno == EINTR)) 349 ; 350 errno = save_errno; 351 } 352 353 /* 354 * Signal handler for the alarm after the login grace period has expired. 355 */ 356 /*ARGSUSED*/ 357 static void 358 grace_alarm_handler(int sig) 359 { 360 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 361 kill(pmonitor->m_pid, SIGALRM); 362 363 /* 364 * Try to kill any processes that we have spawned, E.g. authorized 365 * keys command helpers. 366 */ 367 if (getpgid(0) == getpid()) { 368 signal(SIGTERM, SIG_IGN); 369 kill(0, SIGTERM); 370 } 371 372 /* XXX pre-format ipaddr/port so we don't need to access active_state */ 373 /* Log error and exit. */ 374 sigdie("Timeout before authentication for %s port %d", 375 ssh_remote_ipaddr(the_active_state), 376 ssh_remote_port(the_active_state)); 377 } 378 379 /* Destroy the host and server keys. They will no longer be needed. */ 380 void 381 destroy_sensitive_data(void) 382 { 383 u_int i; 384 385 for (i = 0; i < options.num_host_key_files; i++) { 386 if (sensitive_data.host_keys[i]) { 387 sshkey_free(sensitive_data.host_keys[i]); 388 sensitive_data.host_keys[i] = NULL; 389 } 390 if (sensitive_data.host_certificates[i]) { 391 sshkey_free(sensitive_data.host_certificates[i]); 392 sensitive_data.host_certificates[i] = NULL; 393 } 394 } 395 } 396 397 /* Demote private to public keys for network child */ 398 void 399 demote_sensitive_data(void) 400 { 401 struct sshkey *tmp; 402 u_int i; 403 int r; 404 405 for (i = 0; i < options.num_host_key_files; i++) { 406 if (sensitive_data.host_keys[i]) { 407 if ((r = sshkey_from_private( 408 sensitive_data.host_keys[i], &tmp)) != 0) 409 fatal("could not demote host %s key: %s", 410 sshkey_type(sensitive_data.host_keys[i]), 411 ssh_err(r)); 412 sshkey_free(sensitive_data.host_keys[i]); 413 sensitive_data.host_keys[i] = tmp; 414 } 415 /* Certs do not need demotion */ 416 } 417 } 418 419 static void 420 reseed_prngs(void) 421 { 422 u_int32_t rnd[256]; 423 424 #ifdef WITH_OPENSSL 425 RAND_poll(); 426 #endif 427 arc4random_stir(); /* noop on recent arc4random() implementations */ 428 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 429 430 #ifdef WITH_OPENSSL 431 RAND_seed(rnd, sizeof(rnd)); 432 /* give libcrypto a chance to notice the PID change */ 433 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 434 fatal("%s: RAND_bytes failed", __func__); 435 #endif 436 437 explicit_bzero(rnd, sizeof(rnd)); 438 } 439 440 static void 441 privsep_preauth_child(void) 442 { 443 gid_t gidset[1]; 444 445 /* Enable challenge-response authentication for privilege separation */ 446 privsep_challenge_enable(); 447 448 #ifdef GSSAPI 449 /* Cache supported mechanism OIDs for later use */ 450 ssh_gssapi_prepare_supported_oids(); 451 #endif 452 453 reseed_prngs(); 454 455 /* Demote the private keys to public keys. */ 456 demote_sensitive_data(); 457 458 /* Demote the child */ 459 if (privsep_chroot) { 460 /* Change our root directory */ 461 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 462 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 463 strerror(errno)); 464 if (chdir("/") == -1) 465 fatal("chdir(\"/\"): %s", strerror(errno)); 466 467 /* Drop our privileges */ 468 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 469 (u_int)privsep_pw->pw_gid); 470 gidset[0] = privsep_pw->pw_gid; 471 if (setgroups(1, gidset) < 0) 472 fatal("setgroups: %.100s", strerror(errno)); 473 permanently_set_uid(privsep_pw); 474 } 475 } 476 477 static int 478 privsep_preauth(struct ssh *ssh) 479 { 480 int status, r; 481 pid_t pid; 482 struct ssh_sandbox *box = NULL; 483 484 /* Set up unprivileged child process to deal with network data */ 485 pmonitor = monitor_init(); 486 /* Store a pointer to the kex for later rekeying */ 487 pmonitor->m_pkex = &ssh->kex; 488 489 if (use_privsep == PRIVSEP_ON) 490 box = ssh_sandbox_init(pmonitor); 491 pid = fork(); 492 if (pid == -1) { 493 fatal("fork of unprivileged child failed"); 494 } else if (pid != 0) { 495 debug2("Network child is on pid %ld", (long)pid); 496 497 pmonitor->m_pid = pid; 498 if (have_agent) { 499 r = ssh_get_authentication_socket(&auth_sock); 500 if (r != 0) { 501 error("Could not get agent socket: %s", 502 ssh_err(r)); 503 have_agent = 0; 504 } 505 } 506 if (box != NULL) 507 ssh_sandbox_parent_preauth(box, pid); 508 monitor_child_preauth(ssh, pmonitor); 509 510 /* Wait for the child's exit status */ 511 while (waitpid(pid, &status, 0) < 0) { 512 if (errno == EINTR) 513 continue; 514 pmonitor->m_pid = -1; 515 fatal("%s: waitpid: %s", __func__, strerror(errno)); 516 } 517 privsep_is_preauth = 0; 518 pmonitor->m_pid = -1; 519 if (WIFEXITED(status)) { 520 if (WEXITSTATUS(status) != 0) 521 fatal("%s: preauth child exited with status %d", 522 __func__, WEXITSTATUS(status)); 523 } else if (WIFSIGNALED(status)) 524 fatal("%s: preauth child terminated by signal %d", 525 __func__, WTERMSIG(status)); 526 if (box != NULL) 527 ssh_sandbox_parent_finish(box); 528 return 1; 529 } else { 530 /* child */ 531 close(pmonitor->m_sendfd); 532 close(pmonitor->m_log_recvfd); 533 534 /* Arrange for logging to be sent to the monitor */ 535 set_log_handler(mm_log_handler, pmonitor); 536 537 privsep_preauth_child(); 538 setproctitle("%s", "[net]"); 539 if (box != NULL) 540 ssh_sandbox_child(box); 541 542 return 0; 543 } 544 } 545 546 static void 547 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 548 { 549 #ifdef DISABLE_FD_PASSING 550 if (1) { 551 #else 552 if (authctxt->pw->pw_uid == 0) { 553 #endif 554 /* File descriptor passing is broken or root login */ 555 use_privsep = 0; 556 goto skip; 557 } 558 559 /* New socket pair */ 560 monitor_reinit(pmonitor); 561 562 pmonitor->m_pid = fork(); 563 if (pmonitor->m_pid == -1) 564 fatal("fork of unprivileged child failed"); 565 else if (pmonitor->m_pid != 0) { 566 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 567 sshbuf_reset(loginmsg); 568 monitor_clear_keystate(ssh, pmonitor); 569 monitor_child_postauth(ssh, pmonitor); 570 571 /* NEVERREACHED */ 572 exit(0); 573 } 574 575 /* child */ 576 577 close(pmonitor->m_sendfd); 578 pmonitor->m_sendfd = -1; 579 580 /* Demote the private keys to public keys. */ 581 demote_sensitive_data(); 582 583 reseed_prngs(); 584 585 /* Drop privileges */ 586 do_setusercontext(authctxt->pw); 587 588 skip: 589 /* It is safe now to apply the key state */ 590 monitor_apply_keystate(ssh, pmonitor); 591 592 /* 593 * Tell the packet layer that authentication was successful, since 594 * this information is not part of the key state. 595 */ 596 ssh_packet_set_authenticated(ssh); 597 } 598 599 static void 600 append_hostkey_type(struct sshbuf *b, const char *s) 601 { 602 int r; 603 604 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 605 debug3("%s: %s key not permitted by HostkeyAlgorithms", 606 __func__, s); 607 return; 608 } 609 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 610 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); 611 } 612 613 static char * 614 list_hostkey_types(void) 615 { 616 struct sshbuf *b; 617 struct sshkey *key; 618 char *ret; 619 u_int i; 620 621 if ((b = sshbuf_new()) == NULL) 622 fatal("%s: sshbuf_new failed", __func__); 623 for (i = 0; i < options.num_host_key_files; i++) { 624 key = sensitive_data.host_keys[i]; 625 if (key == NULL) 626 key = sensitive_data.host_pubkeys[i]; 627 if (key == NULL) 628 continue; 629 switch (key->type) { 630 case KEY_RSA: 631 /* for RSA we also support SHA2 signatures */ 632 append_hostkey_type(b, "rsa-sha2-512"); 633 append_hostkey_type(b, "rsa-sha2-256"); 634 /* FALLTHROUGH */ 635 case KEY_DSA: 636 case KEY_ECDSA: 637 case KEY_ED25519: 638 case KEY_XMSS: 639 append_hostkey_type(b, sshkey_ssh_name(key)); 640 break; 641 } 642 /* If the private key has a cert peer, then list that too */ 643 key = sensitive_data.host_certificates[i]; 644 if (key == NULL) 645 continue; 646 switch (key->type) { 647 case KEY_RSA_CERT: 648 /* for RSA we also support SHA2 signatures */ 649 append_hostkey_type(b, 650 "rsa-sha2-512-cert-v01@openssh.com"); 651 append_hostkey_type(b, 652 "rsa-sha2-256-cert-v01@openssh.com"); 653 /* FALLTHROUGH */ 654 case KEY_DSA_CERT: 655 case KEY_ECDSA_CERT: 656 case KEY_ED25519_CERT: 657 case KEY_XMSS_CERT: 658 append_hostkey_type(b, sshkey_ssh_name(key)); 659 break; 660 } 661 } 662 if ((ret = sshbuf_dup_string(b)) == NULL) 663 fatal("%s: sshbuf_dup_string failed", __func__); 664 sshbuf_free(b); 665 debug("%s: %s", __func__, ret); 666 return ret; 667 } 668 669 static struct sshkey * 670 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 671 { 672 u_int i; 673 struct sshkey *key; 674 675 for (i = 0; i < options.num_host_key_files; i++) { 676 switch (type) { 677 case KEY_RSA_CERT: 678 case KEY_DSA_CERT: 679 case KEY_ECDSA_CERT: 680 case KEY_ED25519_CERT: 681 case KEY_XMSS_CERT: 682 key = sensitive_data.host_certificates[i]; 683 break; 684 default: 685 key = sensitive_data.host_keys[i]; 686 if (key == NULL && !need_private) 687 key = sensitive_data.host_pubkeys[i]; 688 break; 689 } 690 if (key != NULL && key->type == type && 691 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 692 return need_private ? 693 sensitive_data.host_keys[i] : key; 694 } 695 return NULL; 696 } 697 698 struct sshkey * 699 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 700 { 701 return get_hostkey_by_type(type, nid, 0, ssh); 702 } 703 704 struct sshkey * 705 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 706 { 707 return get_hostkey_by_type(type, nid, 1, ssh); 708 } 709 710 struct sshkey * 711 get_hostkey_by_index(int ind) 712 { 713 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 714 return (NULL); 715 return (sensitive_data.host_keys[ind]); 716 } 717 718 struct sshkey * 719 get_hostkey_public_by_index(int ind, struct ssh *ssh) 720 { 721 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 722 return (NULL); 723 return (sensitive_data.host_pubkeys[ind]); 724 } 725 726 int 727 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 728 { 729 u_int i; 730 731 for (i = 0; i < options.num_host_key_files; i++) { 732 if (sshkey_is_cert(key)) { 733 if (key == sensitive_data.host_certificates[i] || 734 (compare && sensitive_data.host_certificates[i] && 735 sshkey_equal(key, 736 sensitive_data.host_certificates[i]))) 737 return (i); 738 } else { 739 if (key == sensitive_data.host_keys[i] || 740 (compare && sensitive_data.host_keys[i] && 741 sshkey_equal(key, sensitive_data.host_keys[i]))) 742 return (i); 743 if (key == sensitive_data.host_pubkeys[i] || 744 (compare && sensitive_data.host_pubkeys[i] && 745 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 746 return (i); 747 } 748 } 749 return (-1); 750 } 751 752 /* Inform the client of all hostkeys */ 753 static void 754 notify_hostkeys(struct ssh *ssh) 755 { 756 struct sshbuf *buf; 757 struct sshkey *key; 758 u_int i, nkeys; 759 int r; 760 char *fp; 761 762 /* Some clients cannot cope with the hostkeys message, skip those. */ 763 if (ssh->compat & SSH_BUG_HOSTKEYS) 764 return; 765 766 if ((buf = sshbuf_new()) == NULL) 767 fatal("%s: sshbuf_new", __func__); 768 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 769 key = get_hostkey_public_by_index(i, ssh); 770 if (key == NULL || key->type == KEY_UNSPEC || 771 sshkey_is_cert(key)) 772 continue; 773 fp = sshkey_fingerprint(key, options.fingerprint_hash, 774 SSH_FP_DEFAULT); 775 debug3("%s: key %d: %s %s", __func__, i, 776 sshkey_ssh_name(key), fp); 777 free(fp); 778 if (nkeys == 0) { 779 /* 780 * Start building the request when we find the 781 * first usable key. 782 */ 783 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 784 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 785 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 786 sshpkt_fatal(ssh, r, "%s: start request", __func__); 787 } 788 /* Append the key to the request */ 789 sshbuf_reset(buf); 790 if ((r = sshkey_putb(key, buf)) != 0) 791 fatal("%s: couldn't put hostkey %d: %s", 792 __func__, i, ssh_err(r)); 793 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 794 sshpkt_fatal(ssh, r, "%s: append key", __func__); 795 nkeys++; 796 } 797 debug3("%s: sent %u hostkeys", __func__, nkeys); 798 if (nkeys == 0) 799 fatal("%s: no hostkeys", __func__); 800 if ((r = sshpkt_send(ssh)) != 0) 801 sshpkt_fatal(ssh, r, "%s: send", __func__); 802 sshbuf_free(buf); 803 } 804 805 /* 806 * returns 1 if connection should be dropped, 0 otherwise. 807 * dropping starts at connection #max_startups_begin with a probability 808 * of (max_startups_rate/100). the probability increases linearly until 809 * all connections are dropped for startups > max_startups 810 */ 811 static int 812 drop_connection(int startups) 813 { 814 int p, r; 815 816 if (startups < options.max_startups_begin) 817 return 0; 818 if (startups >= options.max_startups) 819 return 1; 820 if (options.max_startups_rate == 100) 821 return 1; 822 823 p = 100 - options.max_startups_rate; 824 p *= startups - options.max_startups_begin; 825 p /= options.max_startups - options.max_startups_begin; 826 p += options.max_startups_rate; 827 r = arc4random_uniform(100); 828 829 debug("drop_connection: p %d, r %d", p, r); 830 return (r < p) ? 1 : 0; 831 } 832 833 static void 834 usage(void) 835 { 836 fprintf(stderr, "%s, %s\n", 837 SSH_RELEASE, 838 #ifdef WITH_OPENSSL 839 OpenSSL_version(OPENSSL_VERSION) 840 #else 841 "without OpenSSL" 842 #endif 843 ); 844 fprintf(stderr, 845 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 846 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 847 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 848 ); 849 exit(1); 850 } 851 852 static void 853 send_rexec_state(int fd, struct sshbuf *conf) 854 { 855 struct sshbuf *m; 856 int r; 857 858 debug3("%s: entering fd = %d config len %zu", __func__, fd, 859 sshbuf_len(conf)); 860 861 /* 862 * Protocol from reexec master to child: 863 * string configuration 864 * string rngseed (only if OpenSSL is not self-seeded) 865 */ 866 if ((m = sshbuf_new()) == NULL) 867 fatal("%s: sshbuf_new failed", __func__); 868 if ((r = sshbuf_put_stringb(m, conf)) != 0) 869 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 870 871 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 872 rexec_send_rng_seed(m); 873 #endif 874 875 if (ssh_msg_send(fd, 0, m) == -1) 876 fatal("%s: ssh_msg_send failed", __func__); 877 878 sshbuf_free(m); 879 880 debug3("%s: done", __func__); 881 } 882 883 static void 884 recv_rexec_state(int fd, struct sshbuf *conf) 885 { 886 struct sshbuf *m; 887 u_char *cp, ver; 888 size_t len; 889 int r; 890 891 debug3("%s: entering fd = %d", __func__, fd); 892 893 if ((m = sshbuf_new()) == NULL) 894 fatal("%s: sshbuf_new failed", __func__); 895 if (ssh_msg_recv(fd, m) == -1) 896 fatal("%s: ssh_msg_recv failed", __func__); 897 if ((r = sshbuf_get_u8(m, &ver)) != 0) 898 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 899 if (ver != 0) 900 fatal("%s: rexec version mismatch", __func__); 901 if ((r = sshbuf_get_string(m, &cp, &len)) != 0) 902 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 903 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 904 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 905 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 906 rexec_recv_rng_seed(m); 907 #endif 908 909 free(cp); 910 sshbuf_free(m); 911 912 debug3("%s: done", __func__); 913 } 914 915 /* Accept a connection from inetd */ 916 static void 917 server_accept_inetd(int *sock_in, int *sock_out) 918 { 919 int fd; 920 921 if (rexeced_flag) { 922 close(REEXEC_CONFIG_PASS_FD); 923 *sock_in = *sock_out = dup(STDIN_FILENO); 924 } else { 925 *sock_in = dup(STDIN_FILENO); 926 *sock_out = dup(STDOUT_FILENO); 927 } 928 /* 929 * We intentionally do not close the descriptors 0, 1, and 2 930 * as our code for setting the descriptors won't work if 931 * ttyfd happens to be one of those. 932 */ 933 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 934 dup2(fd, STDIN_FILENO); 935 dup2(fd, STDOUT_FILENO); 936 if (!log_stderr) 937 dup2(fd, STDERR_FILENO); 938 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 939 close(fd); 940 } 941 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 942 } 943 944 /* 945 * Listen for TCP connections 946 */ 947 static void 948 listen_on_addrs(struct listenaddr *la) 949 { 950 int ret, listen_sock; 951 struct addrinfo *ai; 952 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 953 954 for (ai = la->addrs; ai; ai = ai->ai_next) { 955 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 956 continue; 957 if (num_listen_socks >= MAX_LISTEN_SOCKS) 958 fatal("Too many listen sockets. " 959 "Enlarge MAX_LISTEN_SOCKS"); 960 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 961 ntop, sizeof(ntop), strport, sizeof(strport), 962 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 963 error("getnameinfo failed: %.100s", 964 ssh_gai_strerror(ret)); 965 continue; 966 } 967 /* Create socket for listening. */ 968 listen_sock = socket(ai->ai_family, ai->ai_socktype, 969 ai->ai_protocol); 970 if (listen_sock < 0) { 971 /* kernel may not support ipv6 */ 972 verbose("socket: %.100s", strerror(errno)); 973 continue; 974 } 975 if (set_nonblock(listen_sock) == -1) { 976 close(listen_sock); 977 continue; 978 } 979 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 980 verbose("socket: CLOEXEC: %s", strerror(errno)); 981 close(listen_sock); 982 continue; 983 } 984 /* Socket options */ 985 set_reuseaddr(listen_sock); 986 if (la->rdomain != NULL && 987 set_rdomain(listen_sock, la->rdomain) == -1) { 988 close(listen_sock); 989 continue; 990 } 991 992 /* Only communicate in IPv6 over AF_INET6 sockets. */ 993 if (ai->ai_family == AF_INET6) 994 sock_set_v6only(listen_sock); 995 996 debug("Bind to port %s on %s.", strport, ntop); 997 998 /* Bind the socket to the desired port. */ 999 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1000 error("Bind to port %s on %s failed: %.200s.", 1001 strport, ntop, strerror(errno)); 1002 close(listen_sock); 1003 continue; 1004 } 1005 listen_socks[num_listen_socks] = listen_sock; 1006 num_listen_socks++; 1007 1008 /* Start listening on the port. */ 1009 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1010 fatal("listen on [%s]:%s: %.100s", 1011 ntop, strport, strerror(errno)); 1012 logit("Server listening on %s port %s%s%s.", 1013 ntop, strport, 1014 la->rdomain == NULL ? "" : " rdomain ", 1015 la->rdomain == NULL ? "" : la->rdomain); 1016 } 1017 } 1018 1019 static void 1020 server_listen(void) 1021 { 1022 u_int i; 1023 1024 for (i = 0; i < options.num_listen_addrs; i++) { 1025 listen_on_addrs(&options.listen_addrs[i]); 1026 freeaddrinfo(options.listen_addrs[i].addrs); 1027 free(options.listen_addrs[i].rdomain); 1028 memset(&options.listen_addrs[i], 0, 1029 sizeof(options.listen_addrs[i])); 1030 } 1031 free(options.listen_addrs); 1032 options.listen_addrs = NULL; 1033 options.num_listen_addrs = 0; 1034 1035 if (!num_listen_socks) 1036 fatal("Cannot bind any address."); 1037 } 1038 1039 /* 1040 * The main TCP accept loop. Note that, for the non-debug case, returns 1041 * from this function are in a forked subprocess. 1042 */ 1043 static void 1044 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1045 { 1046 fd_set *fdset; 1047 int i, j, ret, maxfd; 1048 int startups = 0, listening = 0, lameduck = 0; 1049 int startup_p[2] = { -1 , -1 }; 1050 char c = 0; 1051 struct sockaddr_storage from; 1052 socklen_t fromlen; 1053 pid_t pid; 1054 u_char rnd[256]; 1055 1056 /* setup fd set for accept */ 1057 fdset = NULL; 1058 maxfd = 0; 1059 for (i = 0; i < num_listen_socks; i++) 1060 if (listen_socks[i] > maxfd) 1061 maxfd = listen_socks[i]; 1062 /* pipes connected to unauthenticated childs */ 1063 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1064 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1065 for (i = 0; i < options.max_startups; i++) 1066 startup_pipes[i] = -1; 1067 1068 /* 1069 * Stay listening for connections until the system crashes or 1070 * the daemon is killed with a signal. 1071 */ 1072 for (;;) { 1073 if (received_sighup) { 1074 if (!lameduck) { 1075 debug("Received SIGHUP; waiting for children"); 1076 close_listen_socks(); 1077 lameduck = 1; 1078 } 1079 if (listening <= 0) 1080 sighup_restart(); 1081 } 1082 free(fdset); 1083 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1084 sizeof(fd_mask)); 1085 1086 for (i = 0; i < num_listen_socks; i++) 1087 FD_SET(listen_socks[i], fdset); 1088 for (i = 0; i < options.max_startups; i++) 1089 if (startup_pipes[i] != -1) 1090 FD_SET(startup_pipes[i], fdset); 1091 1092 /* Wait in select until there is a connection. */ 1093 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1094 if (ret < 0 && errno != EINTR) 1095 error("select: %.100s", strerror(errno)); 1096 if (received_sigterm) { 1097 logit("Received signal %d; terminating.", 1098 (int) received_sigterm); 1099 close_listen_socks(); 1100 if (options.pid_file != NULL) 1101 unlink(options.pid_file); 1102 exit(received_sigterm == SIGTERM ? 0 : 255); 1103 } 1104 if (ret < 0) 1105 continue; 1106 1107 for (i = 0; i < options.max_startups; i++) { 1108 if (startup_pipes[i] == -1 || 1109 !FD_ISSET(startup_pipes[i], fdset)) 1110 continue; 1111 switch (read(startup_pipes[i], &c, sizeof(c))) { 1112 case -1: 1113 if (errno == EINTR || errno == EAGAIN) 1114 continue; 1115 if (errno != EPIPE) { 1116 error("%s: startup pipe %d (fd=%d): " 1117 "read %s", __func__, i, 1118 startup_pipes[i], strerror(errno)); 1119 } 1120 /* FALLTHROUGH */ 1121 case 0: 1122 /* child exited or completed auth */ 1123 close(startup_pipes[i]); 1124 startup_pipes[i] = -1; 1125 startups--; 1126 if (startup_flags[i]) 1127 listening--; 1128 break; 1129 case 1: 1130 /* child has finished preliminaries */ 1131 if (startup_flags[i]) { 1132 listening--; 1133 startup_flags[i] = 0; 1134 } 1135 break; 1136 } 1137 } 1138 for (i = 0; i < num_listen_socks; i++) { 1139 if (!FD_ISSET(listen_socks[i], fdset)) 1140 continue; 1141 fromlen = sizeof(from); 1142 *newsock = accept(listen_socks[i], 1143 (struct sockaddr *)&from, &fromlen); 1144 if (*newsock < 0) { 1145 if (errno != EINTR && errno != EWOULDBLOCK && 1146 errno != ECONNABORTED && errno != EAGAIN) 1147 error("accept: %.100s", 1148 strerror(errno)); 1149 if (errno == EMFILE || errno == ENFILE) 1150 usleep(100 * 1000); 1151 continue; 1152 } 1153 if (unset_nonblock(*newsock) == -1) { 1154 close(*newsock); 1155 continue; 1156 } 1157 if (drop_connection(startups) == 1) { 1158 char *laddr = get_local_ipaddr(*newsock); 1159 char *raddr = get_peer_ipaddr(*newsock); 1160 1161 verbose("drop connection #%d from [%s]:%d " 1162 "on [%s]:%d past MaxStartups", startups, 1163 raddr, get_peer_port(*newsock), 1164 laddr, get_local_port(*newsock)); 1165 free(laddr); 1166 free(raddr); 1167 close(*newsock); 1168 continue; 1169 } 1170 if (pipe(startup_p) == -1) { 1171 close(*newsock); 1172 continue; 1173 } 1174 1175 if (rexec_flag && socketpair(AF_UNIX, 1176 SOCK_STREAM, 0, config_s) == -1) { 1177 error("reexec socketpair: %s", 1178 strerror(errno)); 1179 close(*newsock); 1180 close(startup_p[0]); 1181 close(startup_p[1]); 1182 continue; 1183 } 1184 1185 for (j = 0; j < options.max_startups; j++) 1186 if (startup_pipes[j] == -1) { 1187 startup_pipes[j] = startup_p[0]; 1188 if (maxfd < startup_p[0]) 1189 maxfd = startup_p[0]; 1190 startups++; 1191 startup_flags[j] = 1; 1192 break; 1193 } 1194 1195 /* 1196 * Got connection. Fork a child to handle it, unless 1197 * we are in debugging mode. 1198 */ 1199 if (debug_flag) { 1200 /* 1201 * In debugging mode. Close the listening 1202 * socket, and start processing the 1203 * connection without forking. 1204 */ 1205 debug("Server will not fork when running in debugging mode."); 1206 close_listen_socks(); 1207 *sock_in = *newsock; 1208 *sock_out = *newsock; 1209 close(startup_p[0]); 1210 close(startup_p[1]); 1211 startup_pipe = -1; 1212 pid = getpid(); 1213 if (rexec_flag) { 1214 send_rexec_state(config_s[0], cfg); 1215 close(config_s[0]); 1216 } 1217 return; 1218 } 1219 1220 /* 1221 * Normal production daemon. Fork, and have 1222 * the child process the connection. The 1223 * parent continues listening. 1224 */ 1225 platform_pre_fork(); 1226 listening++; 1227 if ((pid = fork()) == 0) { 1228 /* 1229 * Child. Close the listening and 1230 * max_startup sockets. Start using 1231 * the accepted socket. Reinitialize 1232 * logging (since our pid has changed). 1233 * We return from this function to handle 1234 * the connection. 1235 */ 1236 platform_post_fork_child(); 1237 startup_pipe = startup_p[1]; 1238 close_startup_pipes(); 1239 close_listen_socks(); 1240 *sock_in = *newsock; 1241 *sock_out = *newsock; 1242 log_init(__progname, 1243 options.log_level, 1244 options.log_facility, 1245 log_stderr); 1246 if (rexec_flag) 1247 close(config_s[0]); 1248 else { 1249 /* 1250 * Signal parent that the preliminaries 1251 * for this child are complete. For the 1252 * re-exec case, this happens after the 1253 * child has received the rexec state 1254 * from the server. 1255 */ 1256 (void)atomicio(vwrite, startup_pipe, 1257 "\0", 1); 1258 } 1259 return; 1260 } 1261 1262 /* Parent. Stay in the loop. */ 1263 platform_post_fork_parent(pid); 1264 if (pid < 0) 1265 error("fork: %.100s", strerror(errno)); 1266 else 1267 debug("Forked child %ld.", (long)pid); 1268 1269 close(startup_p[1]); 1270 1271 if (rexec_flag) { 1272 send_rexec_state(config_s[0], cfg); 1273 close(config_s[0]); 1274 close(config_s[1]); 1275 } 1276 close(*newsock); 1277 1278 /* 1279 * Ensure that our random state differs 1280 * from that of the child 1281 */ 1282 arc4random_stir(); 1283 arc4random_buf(rnd, sizeof(rnd)); 1284 #ifdef WITH_OPENSSL 1285 RAND_seed(rnd, sizeof(rnd)); 1286 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1287 fatal("%s: RAND_bytes failed", __func__); 1288 #endif 1289 explicit_bzero(rnd, sizeof(rnd)); 1290 } 1291 } 1292 } 1293 1294 /* 1295 * If IP options are supported, make sure there are none (log and 1296 * return an error if any are found). Basically we are worried about 1297 * source routing; it can be used to pretend you are somebody 1298 * (ip-address) you are not. That itself may be "almost acceptable" 1299 * under certain circumstances, but rhosts authentication is useless 1300 * if source routing is accepted. Notice also that if we just dropped 1301 * source routing here, the other side could use IP spoofing to do 1302 * rest of the interaction and could still bypass security. So we 1303 * exit here if we detect any IP options. 1304 */ 1305 static void 1306 check_ip_options(struct ssh *ssh) 1307 { 1308 #ifdef IP_OPTIONS 1309 int sock_in = ssh_packet_get_connection_in(ssh); 1310 struct sockaddr_storage from; 1311 u_char opts[200]; 1312 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1313 char text[sizeof(opts) * 3 + 1]; 1314 1315 memset(&from, 0, sizeof(from)); 1316 if (getpeername(sock_in, (struct sockaddr *)&from, 1317 &fromlen) < 0) 1318 return; 1319 if (from.ss_family != AF_INET) 1320 return; 1321 /* XXX IPv6 options? */ 1322 1323 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1324 &option_size) >= 0 && option_size != 0) { 1325 text[0] = '\0'; 1326 for (i = 0; i < option_size; i++) 1327 snprintf(text + i*3, sizeof(text) - i*3, 1328 " %2.2x", opts[i]); 1329 fatal("Connection from %.100s port %d with IP opts: %.800s", 1330 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1331 } 1332 return; 1333 #endif /* IP_OPTIONS */ 1334 } 1335 1336 /* Set the routing domain for this process */ 1337 static void 1338 set_process_rdomain(struct ssh *ssh, const char *name) 1339 { 1340 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) 1341 if (name == NULL) 1342 return; /* default */ 1343 1344 if (strcmp(name, "%D") == 0) { 1345 /* "expands" to routing domain of connection */ 1346 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1347 return; 1348 } 1349 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ 1350 return sys_set_process_rdomain(name); 1351 #elif defined(__OpenBSD__) 1352 int rtable, ortable = getrtable(); 1353 const char *errstr; 1354 1355 if (name == NULL) 1356 return; /* default */ 1357 1358 if (strcmp(name, "%D") == 0) { 1359 /* "expands" to routing domain of connection */ 1360 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1361 return; 1362 } 1363 1364 rtable = (int)strtonum(name, 0, 255, &errstr); 1365 if (errstr != NULL) /* Shouldn't happen */ 1366 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1367 if (rtable != ortable && setrtable(rtable) != 0) 1368 fatal("Unable to set routing domain %d: %s", 1369 rtable, strerror(errno)); 1370 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1371 #else /* defined(__OpenBSD__) */ 1372 fatal("Unable to set routing domain: not supported in this platform"); 1373 #endif 1374 } 1375 1376 static void 1377 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1378 const struct sshkey *key) 1379 { 1380 static struct ssh_digest_ctx *ctx; 1381 u_char *hash; 1382 size_t len; 1383 struct sshbuf *buf; 1384 int r; 1385 1386 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1387 fatal("%s: ssh_digest_start", __func__); 1388 if (key == NULL) { /* finalize */ 1389 /* add server config in case we are using agent for host keys */ 1390 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1391 sshbuf_len(server_cfg)) != 0) 1392 fatal("%s: ssh_digest_update", __func__); 1393 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1394 hash = xmalloc(len); 1395 if (ssh_digest_final(ctx, hash, len) != 0) 1396 fatal("%s: ssh_digest_final", __func__); 1397 options.timing_secret = PEEK_U64(hash); 1398 freezero(hash, len); 1399 ssh_digest_free(ctx); 1400 ctx = NULL; 1401 return; 1402 } 1403 if ((buf = sshbuf_new()) == NULL) 1404 fatal("%s could not allocate buffer", __func__); 1405 if ((r = sshkey_private_serialize(key, buf)) != 0) 1406 fatal("sshkey_private_serialize: %s", ssh_err(r)); 1407 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1408 fatal("%s: ssh_digest_update", __func__); 1409 sshbuf_reset(buf); 1410 sshbuf_free(buf); 1411 } 1412 1413 /* 1414 * Main program for the daemon. 1415 */ 1416 int 1417 main(int ac, char **av) 1418 { 1419 struct ssh *ssh = NULL; 1420 extern char *optarg; 1421 extern int optind; 1422 int r, opt, on = 1, already_daemon, remote_port; 1423 int sock_in = -1, sock_out = -1, newsock = -1; 1424 const char *remote_ip, *rdomain; 1425 char *fp, *line, *laddr, *logfile = NULL; 1426 int config_s[2] = { -1 , -1 }; 1427 u_int i, j; 1428 u_int64_t ibytes, obytes; 1429 mode_t new_umask; 1430 struct sshkey *key; 1431 struct sshkey *pubkey; 1432 int keytype; 1433 Authctxt *authctxt; 1434 struct connection_info *connection_info = NULL; 1435 1436 ssh_malloc_init(); /* must be called before any mallocs */ 1437 1438 #ifdef HAVE_SECUREWARE 1439 (void)set_auth_parameters(ac, av); 1440 #endif 1441 __progname = ssh_get_progname(av[0]); 1442 1443 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1444 saved_argc = ac; 1445 rexec_argc = ac; 1446 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1447 for (i = 0; (int)i < ac; i++) 1448 saved_argv[i] = xstrdup(av[i]); 1449 saved_argv[i] = NULL; 1450 1451 #ifndef HAVE_SETPROCTITLE 1452 /* Prepare for later setproctitle emulation */ 1453 compat_init_setproctitle(ac, av); 1454 av = saved_argv; 1455 #endif 1456 1457 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1458 debug("setgroups(): %.200s", strerror(errno)); 1459 1460 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1461 sanitise_stdfd(); 1462 1463 seed_rng(); 1464 1465 /* Initialize configuration options to their default values. */ 1466 initialize_server_options(&options); 1467 1468 /* Parse command-line arguments. */ 1469 while ((opt = getopt(ac, av, 1470 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1471 switch (opt) { 1472 case '4': 1473 options.address_family = AF_INET; 1474 break; 1475 case '6': 1476 options.address_family = AF_INET6; 1477 break; 1478 case 'f': 1479 config_file_name = optarg; 1480 break; 1481 case 'c': 1482 servconf_add_hostcert("[command-line]", 0, 1483 &options, optarg); 1484 break; 1485 case 'd': 1486 if (debug_flag == 0) { 1487 debug_flag = 1; 1488 options.log_level = SYSLOG_LEVEL_DEBUG1; 1489 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1490 options.log_level++; 1491 break; 1492 case 'D': 1493 no_daemon_flag = 1; 1494 break; 1495 case 'E': 1496 logfile = optarg; 1497 /* FALLTHROUGH */ 1498 case 'e': 1499 log_stderr = 1; 1500 break; 1501 case 'i': 1502 inetd_flag = 1; 1503 break; 1504 case 'r': 1505 rexec_flag = 0; 1506 break; 1507 case 'R': 1508 rexeced_flag = 1; 1509 inetd_flag = 1; 1510 break; 1511 case 'Q': 1512 /* ignored */ 1513 break; 1514 case 'q': 1515 options.log_level = SYSLOG_LEVEL_QUIET; 1516 break; 1517 case 'b': 1518 /* protocol 1, ignored */ 1519 break; 1520 case 'p': 1521 options.ports_from_cmdline = 1; 1522 if (options.num_ports >= MAX_PORTS) { 1523 fprintf(stderr, "too many ports.\n"); 1524 exit(1); 1525 } 1526 options.ports[options.num_ports++] = a2port(optarg); 1527 if (options.ports[options.num_ports-1] <= 0) { 1528 fprintf(stderr, "Bad port number.\n"); 1529 exit(1); 1530 } 1531 break; 1532 case 'g': 1533 if ((options.login_grace_time = convtime(optarg)) == -1) { 1534 fprintf(stderr, "Invalid login grace time.\n"); 1535 exit(1); 1536 } 1537 break; 1538 case 'k': 1539 /* protocol 1, ignored */ 1540 break; 1541 case 'h': 1542 servconf_add_hostkey("[command-line]", 0, 1543 &options, optarg, 1); 1544 break; 1545 case 't': 1546 test_flag = 1; 1547 break; 1548 case 'T': 1549 test_flag = 2; 1550 break; 1551 case 'C': 1552 connection_info = get_connection_info(ssh, 0, 0); 1553 if (parse_server_match_testspec(connection_info, 1554 optarg) == -1) 1555 exit(1); 1556 break; 1557 case 'u': 1558 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1559 if (utmp_len > HOST_NAME_MAX+1) { 1560 fprintf(stderr, "Invalid utmp length.\n"); 1561 exit(1); 1562 } 1563 break; 1564 case 'o': 1565 line = xstrdup(optarg); 1566 if (process_server_config_line(&options, line, 1567 "command-line", 0, NULL, NULL) != 0) 1568 exit(1); 1569 free(line); 1570 break; 1571 case '?': 1572 default: 1573 usage(); 1574 break; 1575 } 1576 } 1577 if (rexeced_flag || inetd_flag) 1578 rexec_flag = 0; 1579 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1580 fatal("sshd re-exec requires execution with an absolute path"); 1581 if (rexeced_flag) 1582 closefrom(REEXEC_MIN_FREE_FD); 1583 else 1584 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1585 1586 /* If requested, redirect the logs to the specified logfile. */ 1587 if (logfile != NULL) 1588 log_redirect_stderr_to(logfile); 1589 /* 1590 * Force logging to stderr until we have loaded the private host 1591 * key (unless started from inetd) 1592 */ 1593 log_init(__progname, 1594 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1595 SYSLOG_LEVEL_INFO : options.log_level, 1596 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1597 SYSLOG_FACILITY_AUTH : options.log_facility, 1598 log_stderr || !inetd_flag); 1599 1600 /* 1601 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1602 * root's environment 1603 */ 1604 if (getenv("KRB5CCNAME") != NULL) 1605 (void) unsetenv("KRB5CCNAME"); 1606 1607 sensitive_data.have_ssh2_key = 0; 1608 1609 /* 1610 * If we're not doing an extended test do not silently ignore connection 1611 * test params. 1612 */ 1613 if (test_flag < 2 && connection_info != NULL) 1614 fatal("Config test connection parameter (-C) provided without " 1615 "test mode (-T)"); 1616 1617 /* Fetch our configuration */ 1618 if ((cfg = sshbuf_new()) == NULL) 1619 fatal("%s: sshbuf_new failed", __func__); 1620 if (rexeced_flag) { 1621 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1622 if (!debug_flag) { 1623 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1624 close(REEXEC_STARTUP_PIPE_FD); 1625 /* 1626 * Signal parent that this child is at a point where 1627 * they can go away if they have a SIGHUP pending. 1628 */ 1629 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1630 } 1631 } 1632 else if (strcasecmp(config_file_name, "none") != 0) 1633 load_server_config(config_file_name, cfg); 1634 1635 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1636 cfg, NULL); 1637 1638 /* Fill in default values for those options not explicitly set. */ 1639 fill_default_server_options(&options); 1640 1641 /* challenge-response is implemented via keyboard interactive */ 1642 if (options.challenge_response_authentication) 1643 options.kbd_interactive_authentication = 1; 1644 1645 /* Check that options are sensible */ 1646 if (options.authorized_keys_command_user == NULL && 1647 (options.authorized_keys_command != NULL && 1648 strcasecmp(options.authorized_keys_command, "none") != 0)) 1649 fatal("AuthorizedKeysCommand set without " 1650 "AuthorizedKeysCommandUser"); 1651 if (options.authorized_principals_command_user == NULL && 1652 (options.authorized_principals_command != NULL && 1653 strcasecmp(options.authorized_principals_command, "none") != 0)) 1654 fatal("AuthorizedPrincipalsCommand set without " 1655 "AuthorizedPrincipalsCommandUser"); 1656 1657 /* 1658 * Check whether there is any path through configured auth methods. 1659 * Unfortunately it is not possible to verify this generally before 1660 * daemonisation in the presence of Match block, but this catches 1661 * and warns for trivial misconfigurations that could break login. 1662 */ 1663 if (options.num_auth_methods != 0) { 1664 for (i = 0; i < options.num_auth_methods; i++) { 1665 if (auth2_methods_valid(options.auth_methods[i], 1666 1) == 0) 1667 break; 1668 } 1669 if (i >= options.num_auth_methods) 1670 fatal("AuthenticationMethods cannot be satisfied by " 1671 "enabled authentication methods"); 1672 } 1673 1674 /* Check that there are no remaining arguments. */ 1675 if (optind < ac) { 1676 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1677 exit(1); 1678 } 1679 1680 debug("sshd version %s, %s", SSH_VERSION, 1681 #ifdef WITH_OPENSSL 1682 OpenSSL_version(OPENSSL_VERSION) 1683 #else 1684 "without OpenSSL" 1685 #endif 1686 ); 1687 1688 /* Store privilege separation user for later use if required. */ 1689 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); 1690 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1691 if (privsep_chroot || options.kerberos_authentication) 1692 fatal("Privilege separation user %s does not exist", 1693 SSH_PRIVSEP_USER); 1694 } else { 1695 privsep_pw = pwcopy(privsep_pw); 1696 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); 1697 privsep_pw->pw_passwd = xstrdup("*"); 1698 } 1699 endpwent(); 1700 1701 /* load host keys */ 1702 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1703 sizeof(struct sshkey *)); 1704 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1705 sizeof(struct sshkey *)); 1706 1707 if (options.host_key_agent) { 1708 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1709 setenv(SSH_AUTHSOCKET_ENV_NAME, 1710 options.host_key_agent, 1); 1711 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1712 have_agent = 1; 1713 else 1714 error("Could not connect to agent \"%s\": %s", 1715 options.host_key_agent, ssh_err(r)); 1716 } 1717 1718 for (i = 0; i < options.num_host_key_files; i++) { 1719 int ll = options.host_key_file_userprovided[i] ? 1720 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1721 1722 if (options.host_key_files[i] == NULL) 1723 continue; 1724 if ((r = sshkey_load_private(options.host_key_files[i], "", 1725 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1726 do_log2(ll, "Unable to load host key \"%s\": %s", 1727 options.host_key_files[i], ssh_err(r)); 1728 if ((r = sshkey_load_public(options.host_key_files[i], 1729 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1730 do_log2(ll, "Unable to load host key \"%s\": %s", 1731 options.host_key_files[i], ssh_err(r)); 1732 if (pubkey == NULL && key != NULL) 1733 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1734 fatal("Could not demote key: \"%s\": %s", 1735 options.host_key_files[i], ssh_err(r)); 1736 sensitive_data.host_keys[i] = key; 1737 sensitive_data.host_pubkeys[i] = pubkey; 1738 1739 if (key == NULL && pubkey != NULL && have_agent) { 1740 debug("will rely on agent for hostkey %s", 1741 options.host_key_files[i]); 1742 keytype = pubkey->type; 1743 } else if (key != NULL) { 1744 keytype = key->type; 1745 accumulate_host_timing_secret(cfg, key); 1746 } else { 1747 do_log2(ll, "Unable to load host key: %s", 1748 options.host_key_files[i]); 1749 sensitive_data.host_keys[i] = NULL; 1750 sensitive_data.host_pubkeys[i] = NULL; 1751 continue; 1752 } 1753 1754 switch (keytype) { 1755 case KEY_RSA: 1756 case KEY_DSA: 1757 case KEY_ECDSA: 1758 case KEY_ED25519: 1759 case KEY_XMSS: 1760 if (have_agent || key != NULL) 1761 sensitive_data.have_ssh2_key = 1; 1762 break; 1763 } 1764 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1765 SSH_FP_DEFAULT)) == NULL) 1766 fatal("sshkey_fingerprint failed"); 1767 debug("%s host key #%d: %s %s", 1768 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1769 free(fp); 1770 } 1771 accumulate_host_timing_secret(cfg, NULL); 1772 if (!sensitive_data.have_ssh2_key) { 1773 logit("sshd: no hostkeys available -- exiting."); 1774 exit(1); 1775 } 1776 1777 /* 1778 * Load certificates. They are stored in an array at identical 1779 * indices to the public keys that they relate to. 1780 */ 1781 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1782 sizeof(struct sshkey *)); 1783 for (i = 0; i < options.num_host_key_files; i++) 1784 sensitive_data.host_certificates[i] = NULL; 1785 1786 for (i = 0; i < options.num_host_cert_files; i++) { 1787 if (options.host_cert_files[i] == NULL) 1788 continue; 1789 if ((r = sshkey_load_public(options.host_cert_files[i], 1790 &key, NULL)) != 0) { 1791 error("Could not load host certificate \"%s\": %s", 1792 options.host_cert_files[i], ssh_err(r)); 1793 continue; 1794 } 1795 if (!sshkey_is_cert(key)) { 1796 error("Certificate file is not a certificate: %s", 1797 options.host_cert_files[i]); 1798 sshkey_free(key); 1799 continue; 1800 } 1801 /* Find matching private key */ 1802 for (j = 0; j < options.num_host_key_files; j++) { 1803 if (sshkey_equal_public(key, 1804 sensitive_data.host_keys[j])) { 1805 sensitive_data.host_certificates[j] = key; 1806 break; 1807 } 1808 } 1809 if (j >= options.num_host_key_files) { 1810 error("No matching private key for certificate: %s", 1811 options.host_cert_files[i]); 1812 sshkey_free(key); 1813 continue; 1814 } 1815 sensitive_data.host_certificates[j] = key; 1816 debug("host certificate: #%u type %d %s", j, key->type, 1817 sshkey_type(key)); 1818 } 1819 1820 if (privsep_chroot) { 1821 struct stat st; 1822 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 1828 #ifdef HAVE_CYGWIN 1829 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1830 (st.st_uid != getuid () || 1831 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1832 #else 1833 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1834 #endif 1835 fatal("%s must be owned by root and not group or " 1836 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1837 } 1838 1839 if (test_flag > 1) { 1840 /* 1841 * If no connection info was provided by -C then use 1842 * use a blank one that will cause no predicate to match. 1843 */ 1844 if (connection_info == NULL) 1845 connection_info = get_connection_info(ssh, 0, 0); 1846 parse_server_match_config(&options, connection_info); 1847 dump_config(&options); 1848 } 1849 1850 /* Configuration looks good, so exit if in test mode. */ 1851 if (test_flag) 1852 exit(0); 1853 1854 /* 1855 * Clear out any supplemental groups we may have inherited. This 1856 * prevents inadvertent creation of files with bad modes (in the 1857 * portable version at least, it's certainly possible for PAM 1858 * to create a file, and we can't control the code in every 1859 * module which might be used). 1860 */ 1861 if (setgroups(0, NULL) < 0) 1862 debug("setgroups() failed: %.200s", strerror(errno)); 1863 1864 if (rexec_flag) { 1865 if (rexec_argc < 0) 1866 fatal("rexec_argc %d < 0", rexec_argc); 1867 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1868 for (i = 0; i < (u_int)rexec_argc; i++) { 1869 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1870 rexec_argv[i] = saved_argv[i]; 1871 } 1872 rexec_argv[rexec_argc] = "-R"; 1873 rexec_argv[rexec_argc + 1] = NULL; 1874 } 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, options.log_facility, log_stderr); 1884 1885 /* 1886 * If not in debugging mode, not started from inetd and not already 1887 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1888 * terminal, and fork. The original process exits. 1889 */ 1890 already_daemon = daemonized(); 1891 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1892 1893 if (daemon(0, 0) < 0) 1894 fatal("daemon() failed: %.200s", strerror(errno)); 1895 1896 disconnect_controlling_tty(); 1897 } 1898 /* Reinitialize the log (because of the fork above). */ 1899 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1900 1901 /* Chdir to the root directory so that the current disk can be 1902 unmounted if desired. */ 1903 if (chdir("/") == -1) 1904 error("chdir(\"/\"): %s", strerror(errno)); 1905 1906 /* ignore SIGPIPE */ 1907 signal(SIGPIPE, SIG_IGN); 1908 1909 /* Get a connection, either from inetd or a listening TCP socket */ 1910 if (inetd_flag) { 1911 server_accept_inetd(&sock_in, &sock_out); 1912 } else { 1913 platform_pre_listen(); 1914 server_listen(); 1915 1916 signal(SIGHUP, sighup_handler); 1917 signal(SIGCHLD, main_sigchld_handler); 1918 signal(SIGTERM, sigterm_handler); 1919 signal(SIGQUIT, sigterm_handler); 1920 1921 /* 1922 * Write out the pid file after the sigterm handler 1923 * is setup and the listen sockets are bound 1924 */ 1925 if (options.pid_file != NULL && !debug_flag) { 1926 FILE *f = fopen(options.pid_file, "w"); 1927 1928 if (f == NULL) { 1929 error("Couldn't create pid file \"%s\": %s", 1930 options.pid_file, strerror(errno)); 1931 } else { 1932 fprintf(f, "%ld\n", (long) getpid()); 1933 fclose(f); 1934 } 1935 } 1936 1937 /* Accept a connection and return in a forked child */ 1938 server_accept_loop(&sock_in, &sock_out, 1939 &newsock, config_s); 1940 } 1941 1942 /* This is the child processing a new connection. */ 1943 setproctitle("%s", "[accepted]"); 1944 1945 /* 1946 * Create a new session and process group since the 4.4BSD 1947 * setlogin() affects the entire process group. We don't 1948 * want the child to be able to affect the parent. 1949 */ 1950 #if !defined(SSHD_ACQUIRES_CTTY) 1951 /* 1952 * If setsid is called, on some platforms sshd will later acquire a 1953 * controlling terminal which will result in "could not set 1954 * controlling tty" errors. 1955 */ 1956 if (!debug_flag && !inetd_flag && setsid() < 0) 1957 error("setsid: %.100s", strerror(errno)); 1958 #endif 1959 1960 if (rexec_flag) { 1961 int fd; 1962 1963 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1964 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1965 dup2(newsock, STDIN_FILENO); 1966 dup2(STDIN_FILENO, STDOUT_FILENO); 1967 if (startup_pipe == -1) 1968 close(REEXEC_STARTUP_PIPE_FD); 1969 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1970 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1971 close(startup_pipe); 1972 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1973 } 1974 1975 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1976 close(config_s[1]); 1977 1978 execv(rexec_argv[0], rexec_argv); 1979 1980 /* Reexec has failed, fall back and continue */ 1981 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1982 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1983 log_init(__progname, options.log_level, 1984 options.log_facility, log_stderr); 1985 1986 /* Clean up fds */ 1987 close(REEXEC_CONFIG_PASS_FD); 1988 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1989 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1990 dup2(fd, STDIN_FILENO); 1991 dup2(fd, STDOUT_FILENO); 1992 if (fd > STDERR_FILENO) 1993 close(fd); 1994 } 1995 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1996 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1997 } 1998 1999 /* Executed child processes don't need these. */ 2000 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2001 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2002 2003 /* 2004 * Disable the key regeneration alarm. We will not regenerate the 2005 * key since we are no longer in a position to give it to anyone. We 2006 * will not restart on SIGHUP since it no longer makes sense. 2007 */ 2008 alarm(0); 2009 signal(SIGALRM, SIG_DFL); 2010 signal(SIGHUP, SIG_DFL); 2011 signal(SIGTERM, SIG_DFL); 2012 signal(SIGQUIT, SIG_DFL); 2013 signal(SIGCHLD, SIG_DFL); 2014 signal(SIGINT, SIG_DFL); 2015 2016 /* 2017 * Register our connection. This turns encryption off because we do 2018 * not have a key. 2019 */ 2020 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2021 fatal("Unable to create connection"); 2022 the_active_state = ssh; 2023 ssh_packet_set_server(ssh); 2024 2025 check_ip_options(ssh); 2026 2027 /* Prepare the channels layer */ 2028 channel_init_channels(ssh); 2029 channel_set_af(ssh, options.address_family); 2030 process_permitopen(ssh, &options); 2031 2032 /* Set SO_KEEPALIVE if requested. */ 2033 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2034 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2035 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2036 2037 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2038 debug("ssh_remote_port failed"); 2039 cleanup_exit(255); 2040 } 2041 2042 if (options.routing_domain != NULL) 2043 set_process_rdomain(ssh, options.routing_domain); 2044 2045 /* 2046 * The rest of the code depends on the fact that 2047 * ssh_remote_ipaddr() caches the remote ip, even if 2048 * the socket goes away. 2049 */ 2050 remote_ip = ssh_remote_ipaddr(ssh); 2051 2052 #ifdef SSH_AUDIT_EVENTS 2053 audit_connection_from(remote_ip, remote_port); 2054 #endif 2055 2056 rdomain = ssh_packet_rdomain_in(ssh); 2057 2058 /* Log the connection. */ 2059 laddr = get_local_ipaddr(sock_in); 2060 verbose("Connection from %s port %d on %s port %d%s%s%s", 2061 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2062 rdomain == NULL ? "" : " rdomain \"", 2063 rdomain == NULL ? "" : rdomain, 2064 rdomain == NULL ? "" : "\""); 2065 free(laddr); 2066 2067 /* 2068 * We don't want to listen forever unless the other side 2069 * successfully authenticates itself. So we set up an alarm which is 2070 * cleared after successful authentication. A limit of zero 2071 * indicates no limit. Note that we don't set the alarm in debugging 2072 * mode; it is just annoying to have the server exit just when you 2073 * are about to discover the bug. 2074 */ 2075 signal(SIGALRM, grace_alarm_handler); 2076 if (!debug_flag) 2077 alarm(options.login_grace_time); 2078 2079 if (kex_exchange_identification(ssh, -1, options.version_addendum) != 0) 2080 cleanup_exit(255); /* error already logged */ 2081 2082 ssh_packet_set_nonblocking(ssh); 2083 2084 /* allocate authentication context */ 2085 authctxt = xcalloc(1, sizeof(*authctxt)); 2086 ssh->authctxt = authctxt; 2087 2088 authctxt->loginmsg = loginmsg; 2089 2090 /* XXX global for cleanup, access from other modules */ 2091 the_authctxt = authctxt; 2092 2093 /* Set default key authentication options */ 2094 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2095 fatal("allocation failed"); 2096 2097 /* prepare buffer to collect messages to display to user after login */ 2098 if ((loginmsg = sshbuf_new()) == NULL) 2099 fatal("%s: sshbuf_new failed", __func__); 2100 auth_debug_reset(); 2101 2102 if (use_privsep) { 2103 if (privsep_preauth(ssh) == 1) 2104 goto authenticated; 2105 } else if (have_agent) { 2106 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2107 error("Unable to get agent socket: %s", ssh_err(r)); 2108 have_agent = 0; 2109 } 2110 } 2111 2112 /* perform the key exchange */ 2113 /* authenticate user and start session */ 2114 do_ssh2_kex(ssh); 2115 do_authentication2(ssh); 2116 2117 /* 2118 * If we use privilege separation, the unprivileged child transfers 2119 * the current keystate and exits 2120 */ 2121 if (use_privsep) { 2122 mm_send_keystate(ssh, pmonitor); 2123 ssh_packet_clear_keys(ssh); 2124 exit(0); 2125 } 2126 2127 authenticated: 2128 /* 2129 * Cancel the alarm we set to limit the time taken for 2130 * authentication. 2131 */ 2132 alarm(0); 2133 signal(SIGALRM, SIG_DFL); 2134 authctxt->authenticated = 1; 2135 if (startup_pipe != -1) { 2136 close(startup_pipe); 2137 startup_pipe = -1; 2138 } 2139 2140 #ifdef SSH_AUDIT_EVENTS 2141 audit_event(ssh, SSH_AUTH_SUCCESS); 2142 #endif 2143 2144 #ifdef GSSAPI 2145 if (options.gss_authentication) { 2146 temporarily_use_uid(authctxt->pw); 2147 ssh_gssapi_storecreds(); 2148 restore_uid(); 2149 } 2150 #endif 2151 #ifdef USE_PAM 2152 if (options.use_pam) { 2153 do_pam_setcred(1); 2154 do_pam_session(ssh); 2155 } 2156 #endif 2157 2158 /* 2159 * In privilege separation, we fork another child and prepare 2160 * file descriptor passing. 2161 */ 2162 if (use_privsep) { 2163 privsep_postauth(ssh, authctxt); 2164 /* the monitor process [priv] will not return */ 2165 } 2166 2167 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2168 options.client_alive_count_max); 2169 2170 /* Try to send all our hostkeys to the client */ 2171 notify_hostkeys(ssh); 2172 2173 /* Start session. */ 2174 do_authenticated(ssh, authctxt); 2175 2176 /* The connection has been terminated. */ 2177 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2178 verbose("Transferred: sent %llu, received %llu bytes", 2179 (unsigned long long)obytes, (unsigned long long)ibytes); 2180 2181 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2182 2183 #ifdef USE_PAM 2184 if (options.use_pam) 2185 finish_pam(); 2186 #endif /* USE_PAM */ 2187 2188 #ifdef SSH_AUDIT_EVENTS 2189 PRIVSEP(audit_event(ssh, SSH_CONNECTION_CLOSE)); 2190 #endif 2191 2192 ssh_packet_close(ssh); 2193 2194 if (use_privsep) 2195 mm_terminate(); 2196 2197 exit(0); 2198 } 2199 2200 int 2201 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2202 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2203 const u_char *data, size_t dlen, const char *alg) 2204 { 2205 int r; 2206 2207 if (use_privsep) { 2208 if (privkey) { 2209 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2210 data, dlen, alg, ssh->compat) < 0) 2211 fatal("%s: privkey sign failed", __func__); 2212 } else { 2213 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2214 data, dlen, alg, ssh->compat) < 0) 2215 fatal("%s: pubkey sign failed", __func__); 2216 } 2217 } else { 2218 if (privkey) { 2219 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2220 alg, ssh->compat) < 0) 2221 fatal("%s: privkey sign failed", __func__); 2222 } else { 2223 if ((r = ssh_agent_sign(auth_sock, pubkey, 2224 signature, slenp, data, dlen, alg, 2225 ssh->compat)) != 0) { 2226 fatal("%s: agent sign failed: %s", 2227 __func__, ssh_err(r)); 2228 } 2229 } 2230 } 2231 return 0; 2232 } 2233 2234 /* SSH2 key exchange */ 2235 static void 2236 do_ssh2_kex(struct ssh *ssh) 2237 { 2238 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2239 struct kex *kex; 2240 int r; 2241 2242 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2243 options.kex_algorithms); 2244 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2245 options.ciphers); 2246 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2247 options.ciphers); 2248 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2249 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2250 2251 if (options.compression == COMP_NONE) { 2252 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2253 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2254 } 2255 2256 if (options.rekey_limit || options.rekey_interval) 2257 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2258 options.rekey_interval); 2259 2260 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2261 list_hostkey_types()); 2262 2263 /* start key exchange */ 2264 if ((r = kex_setup(ssh, myproposal)) != 0) 2265 fatal("kex_setup: %s", ssh_err(r)); 2266 kex = ssh->kex; 2267 #ifdef WITH_OPENSSL 2268 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2269 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2270 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2271 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2272 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2273 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2274 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2275 # ifdef OPENSSL_HAS_ECC 2276 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2277 # endif 2278 #endif 2279 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2280 kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server; 2281 kex->load_host_public_key=&get_hostkey_public_by_type; 2282 kex->load_host_private_key=&get_hostkey_private_by_type; 2283 kex->host_key_index=&get_hostkey_index; 2284 kex->sign = sshd_hostkey_sign; 2285 2286 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2287 2288 session_id2 = kex->session_id; 2289 session_id2_len = kex->session_id_len; 2290 2291 #ifdef DEBUG_KEXDH 2292 /* send 1st encrypted/maced/compressed message */ 2293 packet_start(SSH2_MSG_IGNORE); 2294 packet_put_cstring("markus"); 2295 packet_send(); 2296 packet_write_wait(); 2297 #endif 2298 debug("KEX done"); 2299 } 2300 2301 /* server specific fatal cleanup */ 2302 void 2303 cleanup_exit(int i) 2304 { 2305 if (the_active_state != NULL && the_authctxt != NULL) { 2306 do_cleanup(the_active_state, the_authctxt); 2307 if (use_privsep && privsep_is_preauth && 2308 pmonitor != NULL && pmonitor->m_pid > 1) { 2309 debug("Killing privsep child %d", pmonitor->m_pid); 2310 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2311 errno != ESRCH) 2312 error("%s: kill(%d): %s", __func__, 2313 pmonitor->m_pid, strerror(errno)); 2314 } 2315 } 2316 #ifdef SSH_AUDIT_EVENTS 2317 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2318 if (the_active_state != NULL && (!use_privsep || mm_is_monitor())) 2319 audit_event(the_active_state, SSH_CONNECTION_ABANDON); 2320 #endif 2321 _exit(i); 2322 } 2323