1 /* $OpenBSD: sshd.c,v 1.552 2020/03/13 04:01:57 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 #include "sk-api.h" 126 127 /* Re-exec fds */ 128 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 129 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 130 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 131 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 132 133 extern char *__progname; 134 135 /* Server configuration options. */ 136 ServerOptions options; 137 138 /* Name of the server configuration file. */ 139 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 140 141 /* 142 * Debug mode flag. This can be set on the command line. If debug 143 * mode is enabled, extra debugging output will be sent to the system 144 * log, the daemon will not go to background, and will exit after processing 145 * the first connection. 146 */ 147 int debug_flag = 0; 148 149 /* 150 * Indicating that the daemon should only test the configuration and keys. 151 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 152 * configuration, optionally using connection information provided by the 153 * "-C" flag. 154 */ 155 static int test_flag = 0; 156 157 /* Flag indicating that the daemon is being started from inetd. */ 158 static int inetd_flag = 0; 159 160 /* Flag indicating that sshd should not detach and become a daemon. */ 161 static int no_daemon_flag = 0; 162 163 /* debug goes to stderr unless inetd_flag is set */ 164 static int log_stderr = 0; 165 166 /* Saved arguments to main(). */ 167 static char **saved_argv; 168 static int saved_argc; 169 170 /* re-exec */ 171 static int rexeced_flag = 0; 172 static int rexec_flag = 1; 173 static int rexec_argc = 0; 174 static char **rexec_argv; 175 176 /* 177 * The sockets that the server is listening; this is used in the SIGHUP 178 * signal handler. 179 */ 180 #define MAX_LISTEN_SOCKS 16 181 static int listen_socks[MAX_LISTEN_SOCKS]; 182 static int num_listen_socks = 0; 183 184 /* Daemon's agent connection */ 185 int auth_sock = -1; 186 static int have_agent = 0; 187 188 /* 189 * Any really sensitive data in the application is contained in this 190 * structure. The idea is that this structure could be locked into memory so 191 * that the pages do not get written into swap. However, there are some 192 * problems. The private key contains BIGNUMs, and we do not (in principle) 193 * have access to the internals of them, and locking just the structure is 194 * not very useful. Currently, memory locking is not implemented. 195 */ 196 struct { 197 struct sshkey **host_keys; /* all private host keys */ 198 struct sshkey **host_pubkeys; /* all public host keys */ 199 struct sshkey **host_certificates; /* all public host certificates */ 200 int have_ssh2_key; 201 } sensitive_data; 202 203 /* This is set to true when a signal is received. */ 204 static volatile sig_atomic_t received_sighup = 0; 205 static volatile sig_atomic_t received_sigterm = 0; 206 207 /* session identifier, used by RSA-auth */ 208 u_char session_id[16]; 209 210 /* same for ssh2 */ 211 u_char *session_id2 = NULL; 212 u_int session_id2_len = 0; 213 214 /* record remote hostname or ip */ 215 u_int utmp_len = HOST_NAME_MAX+1; 216 217 /* 218 * startup_pipes/flags are used for tracking children of the listening sshd 219 * process early in their lifespans. This tracking is needed for three things: 220 * 221 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 222 * connections. 223 * 2) Avoiding a race condition for SIGHUP processing, where child processes 224 * may have listen_socks open that could collide with main listener process 225 * after it restarts. 226 * 3) Ensuring that rexec'd sshd processes have received their initial state 227 * from the parent listen process before handling SIGHUP. 228 * 229 * Child processes signal that they have completed closure of the listen_socks 230 * and (if applicable) received their rexec state by sending a char over their 231 * sock. Child processes signal that authentication has completed by closing 232 * the sock (or by exiting). 233 */ 234 static int *startup_pipes = NULL; 235 static int *startup_flags = NULL; /* Indicates child closed listener */ 236 static int startup_pipe = -1; /* in child */ 237 238 /* variables used for privilege separation */ 239 int use_privsep = -1; 240 struct monitor *pmonitor = NULL; 241 int privsep_is_preauth = 1; 242 static int privsep_chroot = 1; 243 244 /* global connection state and authentication contexts */ 245 Authctxt *the_authctxt = NULL; 246 struct ssh *the_active_state; 247 248 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 249 struct sshauthopt *auth_opts = NULL; 250 251 /* sshd_config buffer */ 252 struct sshbuf *cfg; 253 254 /* Included files from the configuration file */ 255 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 256 257 /* message to be displayed after login */ 258 struct sshbuf *loginmsg; 259 260 /* Unprivileged user */ 261 struct passwd *privsep_pw = NULL; 262 263 /* Prototypes for various functions defined later in this file. */ 264 void destroy_sensitive_data(void); 265 void demote_sensitive_data(void); 266 static void do_ssh2_kex(struct ssh *); 267 268 static char *listener_proctitle; 269 270 /* 271 * Close all listening sockets 272 */ 273 static void 274 close_listen_socks(void) 275 { 276 int i; 277 278 for (i = 0; i < num_listen_socks; i++) 279 close(listen_socks[i]); 280 num_listen_socks = -1; 281 } 282 283 static void 284 close_startup_pipes(void) 285 { 286 int i; 287 288 if (startup_pipes) 289 for (i = 0; i < options.max_startups; i++) 290 if (startup_pipes[i] != -1) 291 close(startup_pipes[i]); 292 } 293 294 /* 295 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 296 * the effect is to reread the configuration file (and to regenerate 297 * the server key). 298 */ 299 300 /*ARGSUSED*/ 301 static void 302 sighup_handler(int sig) 303 { 304 received_sighup = 1; 305 } 306 307 /* 308 * Called from the main program after receiving SIGHUP. 309 * Restarts the server. 310 */ 311 static void 312 sighup_restart(void) 313 { 314 logit("Received SIGHUP; restarting."); 315 if (options.pid_file != NULL) 316 unlink(options.pid_file); 317 platform_pre_restart(); 318 close_listen_socks(); 319 close_startup_pipes(); 320 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 321 execv(saved_argv[0], saved_argv); 322 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 323 strerror(errno)); 324 exit(1); 325 } 326 327 /* 328 * Generic signal handler for terminating signals in the master daemon. 329 */ 330 /*ARGSUSED*/ 331 static void 332 sigterm_handler(int sig) 333 { 334 received_sigterm = sig; 335 } 336 337 /* 338 * SIGCHLD handler. This is called whenever a child dies. This will then 339 * reap any zombies left by exited children. 340 */ 341 /*ARGSUSED*/ 342 static void 343 main_sigchld_handler(int sig) 344 { 345 int save_errno = errno; 346 pid_t pid; 347 int status; 348 349 debug("main_sigchld_handler: %s", strsignal(sig)); 350 351 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 352 (pid == -1 && errno == EINTR)) 353 ; 354 errno = save_errno; 355 } 356 357 /* 358 * Signal handler for the alarm after the login grace period has expired. 359 */ 360 /*ARGSUSED*/ 361 static void 362 grace_alarm_handler(int sig) 363 { 364 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 365 kill(pmonitor->m_pid, SIGALRM); 366 367 /* 368 * Try to kill any processes that we have spawned, E.g. authorized 369 * keys command helpers. 370 */ 371 if (getpgid(0) == getpid()) { 372 ssh_signal(SIGTERM, SIG_IGN); 373 kill(0, SIGTERM); 374 } 375 376 /* XXX pre-format ipaddr/port so we don't need to access active_state */ 377 /* Log error and exit. */ 378 sigdie("Timeout before authentication for %s port %d", 379 ssh_remote_ipaddr(the_active_state), 380 ssh_remote_port(the_active_state)); 381 } 382 383 /* Destroy the host and server keys. They will no longer be needed. */ 384 void 385 destroy_sensitive_data(void) 386 { 387 u_int i; 388 389 for (i = 0; i < options.num_host_key_files; i++) { 390 if (sensitive_data.host_keys[i]) { 391 sshkey_free(sensitive_data.host_keys[i]); 392 sensitive_data.host_keys[i] = NULL; 393 } 394 if (sensitive_data.host_certificates[i]) { 395 sshkey_free(sensitive_data.host_certificates[i]); 396 sensitive_data.host_certificates[i] = NULL; 397 } 398 } 399 } 400 401 /* Demote private to public keys for network child */ 402 void 403 demote_sensitive_data(void) 404 { 405 struct sshkey *tmp; 406 u_int i; 407 int r; 408 409 for (i = 0; i < options.num_host_key_files; i++) { 410 if (sensitive_data.host_keys[i]) { 411 if ((r = sshkey_from_private( 412 sensitive_data.host_keys[i], &tmp)) != 0) 413 fatal("could not demote host %s key: %s", 414 sshkey_type(sensitive_data.host_keys[i]), 415 ssh_err(r)); 416 sshkey_free(sensitive_data.host_keys[i]); 417 sensitive_data.host_keys[i] = tmp; 418 } 419 /* Certs do not need demotion */ 420 } 421 } 422 423 static void 424 reseed_prngs(void) 425 { 426 u_int32_t rnd[256]; 427 428 #ifdef WITH_OPENSSL 429 RAND_poll(); 430 #endif 431 arc4random_stir(); /* noop on recent arc4random() implementations */ 432 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 433 434 #ifdef WITH_OPENSSL 435 RAND_seed(rnd, sizeof(rnd)); 436 /* give libcrypto a chance to notice the PID change */ 437 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 438 fatal("%s: RAND_bytes failed", __func__); 439 #endif 440 441 explicit_bzero(rnd, sizeof(rnd)); 442 } 443 444 static void 445 privsep_preauth_child(void) 446 { 447 gid_t gidset[1]; 448 449 /* Enable challenge-response authentication for privilege separation */ 450 privsep_challenge_enable(); 451 452 #ifdef GSSAPI 453 /* Cache supported mechanism OIDs for later use */ 454 ssh_gssapi_prepare_supported_oids(); 455 #endif 456 457 reseed_prngs(); 458 459 /* Demote the private keys to public keys. */ 460 demote_sensitive_data(); 461 462 /* Demote the child */ 463 if (privsep_chroot) { 464 /* Change our root directory */ 465 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 466 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 467 strerror(errno)); 468 if (chdir("/") == -1) 469 fatal("chdir(\"/\"): %s", strerror(errno)); 470 471 /* Drop our privileges */ 472 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 473 (u_int)privsep_pw->pw_gid); 474 gidset[0] = privsep_pw->pw_gid; 475 if (setgroups(1, gidset) == -1) 476 fatal("setgroups: %.100s", strerror(errno)); 477 permanently_set_uid(privsep_pw); 478 } 479 } 480 481 static int 482 privsep_preauth(struct ssh *ssh) 483 { 484 int status, r; 485 pid_t pid; 486 struct ssh_sandbox *box = NULL; 487 488 /* Set up unprivileged child process to deal with network data */ 489 pmonitor = monitor_init(); 490 /* Store a pointer to the kex for later rekeying */ 491 pmonitor->m_pkex = &ssh->kex; 492 493 if (use_privsep == PRIVSEP_ON) 494 box = ssh_sandbox_init(pmonitor); 495 pid = fork(); 496 if (pid == -1) { 497 fatal("fork of unprivileged child failed"); 498 } else if (pid != 0) { 499 debug2("Network child is on pid %ld", (long)pid); 500 501 pmonitor->m_pid = pid; 502 if (have_agent) { 503 r = ssh_get_authentication_socket(&auth_sock); 504 if (r != 0) { 505 error("Could not get agent socket: %s", 506 ssh_err(r)); 507 have_agent = 0; 508 } 509 } 510 if (box != NULL) 511 ssh_sandbox_parent_preauth(box, pid); 512 monitor_child_preauth(ssh, pmonitor); 513 514 /* Wait for the child's exit status */ 515 while (waitpid(pid, &status, 0) == -1) { 516 if (errno == EINTR) 517 continue; 518 pmonitor->m_pid = -1; 519 fatal("%s: waitpid: %s", __func__, strerror(errno)); 520 } 521 privsep_is_preauth = 0; 522 pmonitor->m_pid = -1; 523 if (WIFEXITED(status)) { 524 if (WEXITSTATUS(status) != 0) 525 fatal("%s: preauth child exited with status %d", 526 __func__, WEXITSTATUS(status)); 527 } else if (WIFSIGNALED(status)) 528 fatal("%s: preauth child terminated by signal %d", 529 __func__, WTERMSIG(status)); 530 if (box != NULL) 531 ssh_sandbox_parent_finish(box); 532 return 1; 533 } else { 534 /* child */ 535 close(pmonitor->m_sendfd); 536 close(pmonitor->m_log_recvfd); 537 538 /* Arrange for logging to be sent to the monitor */ 539 set_log_handler(mm_log_handler, pmonitor); 540 541 privsep_preauth_child(); 542 setproctitle("%s", "[net]"); 543 if (box != NULL) 544 ssh_sandbox_child(box); 545 546 return 0; 547 } 548 } 549 550 static void 551 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 552 { 553 #ifdef DISABLE_FD_PASSING 554 if (1) { 555 #else 556 if (authctxt->pw->pw_uid == 0) { 557 #endif 558 /* File descriptor passing is broken or root login */ 559 use_privsep = 0; 560 goto skip; 561 } 562 563 /* New socket pair */ 564 monitor_reinit(pmonitor); 565 566 pmonitor->m_pid = fork(); 567 if (pmonitor->m_pid == -1) 568 fatal("fork of unprivileged child failed"); 569 else if (pmonitor->m_pid != 0) { 570 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 571 sshbuf_reset(loginmsg); 572 monitor_clear_keystate(ssh, pmonitor); 573 monitor_child_postauth(ssh, pmonitor); 574 575 /* NEVERREACHED */ 576 exit(0); 577 } 578 579 /* child */ 580 581 close(pmonitor->m_sendfd); 582 pmonitor->m_sendfd = -1; 583 584 /* Demote the private keys to public keys. */ 585 demote_sensitive_data(); 586 587 reseed_prngs(); 588 589 /* Drop privileges */ 590 do_setusercontext(authctxt->pw); 591 592 skip: 593 /* It is safe now to apply the key state */ 594 monitor_apply_keystate(ssh, pmonitor); 595 596 /* 597 * Tell the packet layer that authentication was successful, since 598 * this information is not part of the key state. 599 */ 600 ssh_packet_set_authenticated(ssh); 601 } 602 603 static void 604 append_hostkey_type(struct sshbuf *b, const char *s) 605 { 606 int r; 607 608 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 609 debug3("%s: %s key not permitted by HostkeyAlgorithms", 610 __func__, s); 611 return; 612 } 613 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 614 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); 615 } 616 617 static char * 618 list_hostkey_types(void) 619 { 620 struct sshbuf *b; 621 struct sshkey *key; 622 char *ret; 623 u_int i; 624 625 if ((b = sshbuf_new()) == NULL) 626 fatal("%s: sshbuf_new failed", __func__); 627 for (i = 0; i < options.num_host_key_files; i++) { 628 key = sensitive_data.host_keys[i]; 629 if (key == NULL) 630 key = sensitive_data.host_pubkeys[i]; 631 if (key == NULL) 632 continue; 633 switch (key->type) { 634 case KEY_RSA: 635 /* for RSA we also support SHA2 signatures */ 636 append_hostkey_type(b, "rsa-sha2-512"); 637 append_hostkey_type(b, "rsa-sha2-256"); 638 /* FALLTHROUGH */ 639 case KEY_DSA: 640 case KEY_ECDSA: 641 case KEY_ED25519: 642 case KEY_ECDSA_SK: 643 case KEY_ED25519_SK: 644 case KEY_XMSS: 645 append_hostkey_type(b, sshkey_ssh_name(key)); 646 break; 647 } 648 /* If the private key has a cert peer, then list that too */ 649 key = sensitive_data.host_certificates[i]; 650 if (key == NULL) 651 continue; 652 switch (key->type) { 653 case KEY_RSA_CERT: 654 /* for RSA we also support SHA2 signatures */ 655 append_hostkey_type(b, 656 "rsa-sha2-512-cert-v01@openssh.com"); 657 append_hostkey_type(b, 658 "rsa-sha2-256-cert-v01@openssh.com"); 659 /* FALLTHROUGH */ 660 case KEY_DSA_CERT: 661 case KEY_ECDSA_CERT: 662 case KEY_ED25519_CERT: 663 case KEY_ECDSA_SK_CERT: 664 case KEY_ED25519_SK_CERT: 665 case KEY_XMSS_CERT: 666 append_hostkey_type(b, sshkey_ssh_name(key)); 667 break; 668 } 669 } 670 if ((ret = sshbuf_dup_string(b)) == NULL) 671 fatal("%s: sshbuf_dup_string failed", __func__); 672 sshbuf_free(b); 673 debug("%s: %s", __func__, ret); 674 return ret; 675 } 676 677 static struct sshkey * 678 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 679 { 680 u_int i; 681 struct sshkey *key; 682 683 for (i = 0; i < options.num_host_key_files; i++) { 684 switch (type) { 685 case KEY_RSA_CERT: 686 case KEY_DSA_CERT: 687 case KEY_ECDSA_CERT: 688 case KEY_ED25519_CERT: 689 case KEY_ECDSA_SK_CERT: 690 case KEY_ED25519_SK_CERT: 691 case KEY_XMSS_CERT: 692 key = sensitive_data.host_certificates[i]; 693 break; 694 default: 695 key = sensitive_data.host_keys[i]; 696 if (key == NULL && !need_private) 697 key = sensitive_data.host_pubkeys[i]; 698 break; 699 } 700 if (key == NULL || key->type != type) 701 continue; 702 switch (type) { 703 case KEY_ECDSA: 704 case KEY_ECDSA_SK: 705 case KEY_ECDSA_CERT: 706 case KEY_ECDSA_SK_CERT: 707 if (key->ecdsa_nid != nid) 708 continue; 709 /* FALLTHROUGH */ 710 default: 711 return need_private ? 712 sensitive_data.host_keys[i] : key; 713 } 714 } 715 return NULL; 716 } 717 718 struct sshkey * 719 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 720 { 721 return get_hostkey_by_type(type, nid, 0, ssh); 722 } 723 724 struct sshkey * 725 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 726 { 727 return get_hostkey_by_type(type, nid, 1, ssh); 728 } 729 730 struct sshkey * 731 get_hostkey_by_index(int ind) 732 { 733 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 734 return (NULL); 735 return (sensitive_data.host_keys[ind]); 736 } 737 738 struct sshkey * 739 get_hostkey_public_by_index(int ind, struct ssh *ssh) 740 { 741 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 742 return (NULL); 743 return (sensitive_data.host_pubkeys[ind]); 744 } 745 746 int 747 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 748 { 749 u_int i; 750 751 for (i = 0; i < options.num_host_key_files; i++) { 752 if (sshkey_is_cert(key)) { 753 if (key == sensitive_data.host_certificates[i] || 754 (compare && sensitive_data.host_certificates[i] && 755 sshkey_equal(key, 756 sensitive_data.host_certificates[i]))) 757 return (i); 758 } else { 759 if (key == sensitive_data.host_keys[i] || 760 (compare && sensitive_data.host_keys[i] && 761 sshkey_equal(key, sensitive_data.host_keys[i]))) 762 return (i); 763 if (key == sensitive_data.host_pubkeys[i] || 764 (compare && sensitive_data.host_pubkeys[i] && 765 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 766 return (i); 767 } 768 } 769 return (-1); 770 } 771 772 /* Inform the client of all hostkeys */ 773 static void 774 notify_hostkeys(struct ssh *ssh) 775 { 776 struct sshbuf *buf; 777 struct sshkey *key; 778 u_int i, nkeys; 779 int r; 780 char *fp; 781 782 /* Some clients cannot cope with the hostkeys message, skip those. */ 783 if (ssh->compat & SSH_BUG_HOSTKEYS) 784 return; 785 786 if ((buf = sshbuf_new()) == NULL) 787 fatal("%s: sshbuf_new", __func__); 788 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 789 key = get_hostkey_public_by_index(i, ssh); 790 if (key == NULL || key->type == KEY_UNSPEC || 791 sshkey_is_cert(key)) 792 continue; 793 fp = sshkey_fingerprint(key, options.fingerprint_hash, 794 SSH_FP_DEFAULT); 795 debug3("%s: key %d: %s %s", __func__, i, 796 sshkey_ssh_name(key), fp); 797 free(fp); 798 if (nkeys == 0) { 799 /* 800 * Start building the request when we find the 801 * first usable key. 802 */ 803 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 804 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 805 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 806 sshpkt_fatal(ssh, r, "%s: start request", __func__); 807 } 808 /* Append the key to the request */ 809 sshbuf_reset(buf); 810 if ((r = sshkey_putb(key, buf)) != 0) 811 fatal("%s: couldn't put hostkey %d: %s", 812 __func__, i, ssh_err(r)); 813 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 814 sshpkt_fatal(ssh, r, "%s: append key", __func__); 815 nkeys++; 816 } 817 debug3("%s: sent %u hostkeys", __func__, nkeys); 818 if (nkeys == 0) 819 fatal("%s: no hostkeys", __func__); 820 if ((r = sshpkt_send(ssh)) != 0) 821 sshpkt_fatal(ssh, r, "%s: send", __func__); 822 sshbuf_free(buf); 823 } 824 825 /* 826 * returns 1 if connection should be dropped, 0 otherwise. 827 * dropping starts at connection #max_startups_begin with a probability 828 * of (max_startups_rate/100). the probability increases linearly until 829 * all connections are dropped for startups > max_startups 830 */ 831 static int 832 drop_connection(int startups) 833 { 834 int p, r; 835 836 if (startups < options.max_startups_begin) 837 return 0; 838 if (startups >= options.max_startups) 839 return 1; 840 if (options.max_startups_rate == 100) 841 return 1; 842 843 p = 100 - options.max_startups_rate; 844 p *= startups - options.max_startups_begin; 845 p /= options.max_startups - options.max_startups_begin; 846 p += options.max_startups_rate; 847 r = arc4random_uniform(100); 848 849 debug("drop_connection: p %d, r %d", p, r); 850 return (r < p) ? 1 : 0; 851 } 852 853 static void 854 usage(void) 855 { 856 fprintf(stderr, "%s, %s\n", 857 SSH_RELEASE, 858 #ifdef WITH_OPENSSL 859 OpenSSL_version(OPENSSL_VERSION) 860 #else 861 "without OpenSSL" 862 #endif 863 ); 864 fprintf(stderr, 865 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 866 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 867 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 868 ); 869 exit(1); 870 } 871 872 static void 873 send_rexec_state(int fd, struct sshbuf *conf) 874 { 875 struct sshbuf *m = NULL, *inc = NULL; 876 struct include_item *item = NULL; 877 int r; 878 879 debug3("%s: entering fd = %d config len %zu", __func__, fd, 880 sshbuf_len(conf)); 881 882 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 883 fatal("%s: sshbuf_new failed", __func__); 884 885 /* pack includes into a string */ 886 TAILQ_FOREACH(item, &includes, entry) { 887 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 888 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 889 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 890 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 891 } 892 893 /* 894 * Protocol from reexec master to child: 895 * string configuration 896 * string included_files[] { 897 * string selector 898 * string filename 899 * string contents 900 * } 901 * string rng_seed (if required) 902 */ 903 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 904 (r = sshbuf_put_stringb(m, inc)) != 0) 905 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 906 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 907 rexec_send_rng_seed(m); 908 #endif 909 if (ssh_msg_send(fd, 0, m) == -1) 910 fatal("%s: ssh_msg_send failed", __func__); 911 912 sshbuf_free(m); 913 sshbuf_free(inc); 914 915 debug3("%s: done", __func__); 916 } 917 918 static void 919 recv_rexec_state(int fd, struct sshbuf *conf) 920 { 921 struct sshbuf *m, *inc; 922 u_char *cp, ver; 923 size_t len; 924 int r; 925 struct include_item *item; 926 927 debug3("%s: entering fd = %d", __func__, fd); 928 929 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 930 fatal("%s: sshbuf_new failed", __func__); 931 if (ssh_msg_recv(fd, m) == -1) 932 fatal("%s: ssh_msg_recv failed", __func__); 933 if ((r = sshbuf_get_u8(m, &ver)) != 0) 934 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 935 if (ver != 0) 936 fatal("%s: rexec version mismatch", __func__); 937 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 938 (r = sshbuf_get_stringb(m, inc)) != 0) 939 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 940 941 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 942 rexec_recv_rng_seed(m); 943 #endif 944 945 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 946 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 947 948 while (sshbuf_len(inc) != 0) { 949 item = xcalloc(1, sizeof(*item)); 950 if ((item->contents = sshbuf_new()) == NULL) 951 fatal("%s: sshbuf_new failed", __func__); 952 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 953 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 954 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 955 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 956 TAILQ_INSERT_TAIL(&includes, item, entry); 957 } 958 959 free(cp); 960 sshbuf_free(m); 961 962 debug3("%s: done", __func__); 963 } 964 965 /* Accept a connection from inetd */ 966 static void 967 server_accept_inetd(int *sock_in, int *sock_out) 968 { 969 int fd; 970 971 if (rexeced_flag) { 972 close(REEXEC_CONFIG_PASS_FD); 973 *sock_in = *sock_out = dup(STDIN_FILENO); 974 } else { 975 *sock_in = dup(STDIN_FILENO); 976 *sock_out = dup(STDOUT_FILENO); 977 } 978 /* 979 * We intentionally do not close the descriptors 0, 1, and 2 980 * as our code for setting the descriptors won't work if 981 * ttyfd happens to be one of those. 982 */ 983 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 984 dup2(fd, STDIN_FILENO); 985 dup2(fd, STDOUT_FILENO); 986 if (!log_stderr) 987 dup2(fd, STDERR_FILENO); 988 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 989 close(fd); 990 } 991 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 992 } 993 994 /* 995 * Listen for TCP connections 996 */ 997 static void 998 listen_on_addrs(struct listenaddr *la) 999 { 1000 int ret, listen_sock; 1001 struct addrinfo *ai; 1002 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1003 1004 for (ai = la->addrs; ai; ai = ai->ai_next) { 1005 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1006 continue; 1007 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1008 fatal("Too many listen sockets. " 1009 "Enlarge MAX_LISTEN_SOCKS"); 1010 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1011 ntop, sizeof(ntop), strport, sizeof(strport), 1012 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1013 error("getnameinfo failed: %.100s", 1014 ssh_gai_strerror(ret)); 1015 continue; 1016 } 1017 /* Create socket for listening. */ 1018 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1019 ai->ai_protocol); 1020 if (listen_sock == -1) { 1021 /* kernel may not support ipv6 */ 1022 verbose("socket: %.100s", strerror(errno)); 1023 continue; 1024 } 1025 if (set_nonblock(listen_sock) == -1) { 1026 close(listen_sock); 1027 continue; 1028 } 1029 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1030 verbose("socket: CLOEXEC: %s", strerror(errno)); 1031 close(listen_sock); 1032 continue; 1033 } 1034 /* Socket options */ 1035 set_reuseaddr(listen_sock); 1036 if (la->rdomain != NULL && 1037 set_rdomain(listen_sock, la->rdomain) == -1) { 1038 close(listen_sock); 1039 continue; 1040 } 1041 1042 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1043 if (ai->ai_family == AF_INET6) 1044 sock_set_v6only(listen_sock); 1045 1046 debug("Bind to port %s on %s.", strport, ntop); 1047 1048 /* Bind the socket to the desired port. */ 1049 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1050 error("Bind to port %s on %s failed: %.200s.", 1051 strport, ntop, strerror(errno)); 1052 close(listen_sock); 1053 continue; 1054 } 1055 listen_socks[num_listen_socks] = listen_sock; 1056 num_listen_socks++; 1057 1058 /* Start listening on the port. */ 1059 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1060 fatal("listen on [%s]:%s: %.100s", 1061 ntop, strport, strerror(errno)); 1062 logit("Server listening on %s port %s%s%s.", 1063 ntop, strport, 1064 la->rdomain == NULL ? "" : " rdomain ", 1065 la->rdomain == NULL ? "" : la->rdomain); 1066 } 1067 } 1068 1069 static void 1070 server_listen(void) 1071 { 1072 u_int i; 1073 1074 for (i = 0; i < options.num_listen_addrs; i++) { 1075 listen_on_addrs(&options.listen_addrs[i]); 1076 freeaddrinfo(options.listen_addrs[i].addrs); 1077 free(options.listen_addrs[i].rdomain); 1078 memset(&options.listen_addrs[i], 0, 1079 sizeof(options.listen_addrs[i])); 1080 } 1081 free(options.listen_addrs); 1082 options.listen_addrs = NULL; 1083 options.num_listen_addrs = 0; 1084 1085 if (!num_listen_socks) 1086 fatal("Cannot bind any address."); 1087 } 1088 1089 /* 1090 * The main TCP accept loop. Note that, for the non-debug case, returns 1091 * from this function are in a forked subprocess. 1092 */ 1093 static void 1094 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1095 { 1096 fd_set *fdset; 1097 int i, j, ret, maxfd; 1098 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1099 int startup_p[2] = { -1 , -1 }; 1100 char c = 0; 1101 struct sockaddr_storage from; 1102 socklen_t fromlen; 1103 pid_t pid; 1104 u_char rnd[256]; 1105 1106 /* setup fd set for accept */ 1107 fdset = NULL; 1108 maxfd = 0; 1109 for (i = 0; i < num_listen_socks; i++) 1110 if (listen_socks[i] > maxfd) 1111 maxfd = listen_socks[i]; 1112 /* pipes connected to unauthenticated child sshd processes */ 1113 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1114 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1115 for (i = 0; i < options.max_startups; i++) 1116 startup_pipes[i] = -1; 1117 1118 /* 1119 * Stay listening for connections until the system crashes or 1120 * the daemon is killed with a signal. 1121 */ 1122 for (;;) { 1123 if (ostartups != startups) { 1124 setproctitle("%s [listener] %d of %d-%d startups", 1125 listener_proctitle, startups, 1126 options.max_startups_begin, options.max_startups); 1127 ostartups = startups; 1128 } 1129 if (received_sighup) { 1130 if (!lameduck) { 1131 debug("Received SIGHUP; waiting for children"); 1132 close_listen_socks(); 1133 lameduck = 1; 1134 } 1135 if (listening <= 0) 1136 sighup_restart(); 1137 } 1138 free(fdset); 1139 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1140 sizeof(fd_mask)); 1141 1142 for (i = 0; i < num_listen_socks; i++) 1143 FD_SET(listen_socks[i], fdset); 1144 for (i = 0; i < options.max_startups; i++) 1145 if (startup_pipes[i] != -1) 1146 FD_SET(startup_pipes[i], fdset); 1147 1148 /* Wait in select until there is a connection. */ 1149 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1150 if (ret == -1 && errno != EINTR) 1151 error("select: %.100s", strerror(errno)); 1152 if (received_sigterm) { 1153 logit("Received signal %d; terminating.", 1154 (int) received_sigterm); 1155 close_listen_socks(); 1156 if (options.pid_file != NULL) 1157 unlink(options.pid_file); 1158 exit(received_sigterm == SIGTERM ? 0 : 255); 1159 } 1160 if (ret == -1) 1161 continue; 1162 1163 for (i = 0; i < options.max_startups; i++) { 1164 if (startup_pipes[i] == -1 || 1165 !FD_ISSET(startup_pipes[i], fdset)) 1166 continue; 1167 switch (read(startup_pipes[i], &c, sizeof(c))) { 1168 case -1: 1169 if (errno == EINTR || errno == EAGAIN) 1170 continue; 1171 if (errno != EPIPE) { 1172 error("%s: startup pipe %d (fd=%d): " 1173 "read %s", __func__, i, 1174 startup_pipes[i], strerror(errno)); 1175 } 1176 /* FALLTHROUGH */ 1177 case 0: 1178 /* child exited or completed auth */ 1179 close(startup_pipes[i]); 1180 startup_pipes[i] = -1; 1181 startups--; 1182 if (startup_flags[i]) 1183 listening--; 1184 break; 1185 case 1: 1186 /* child has finished preliminaries */ 1187 if (startup_flags[i]) { 1188 listening--; 1189 startup_flags[i] = 0; 1190 } 1191 break; 1192 } 1193 } 1194 for (i = 0; i < num_listen_socks; i++) { 1195 if (!FD_ISSET(listen_socks[i], fdset)) 1196 continue; 1197 fromlen = sizeof(from); 1198 *newsock = accept(listen_socks[i], 1199 (struct sockaddr *)&from, &fromlen); 1200 if (*newsock == -1) { 1201 if (errno != EINTR && errno != EWOULDBLOCK && 1202 errno != ECONNABORTED && errno != EAGAIN) 1203 error("accept: %.100s", 1204 strerror(errno)); 1205 if (errno == EMFILE || errno == ENFILE) 1206 usleep(100 * 1000); 1207 continue; 1208 } 1209 if (unset_nonblock(*newsock) == -1) { 1210 close(*newsock); 1211 continue; 1212 } 1213 if (drop_connection(startups) == 1) { 1214 char *laddr = get_local_ipaddr(*newsock); 1215 char *raddr = get_peer_ipaddr(*newsock); 1216 char msg[] = "Exceeded MaxStartups\r\n"; 1217 1218 verbose("drop connection #%d from [%s]:%d " 1219 "on [%s]:%d past MaxStartups", startups, 1220 raddr, get_peer_port(*newsock), 1221 laddr, get_local_port(*newsock)); 1222 free(laddr); 1223 free(raddr); 1224 /* best-effort notification to client */ 1225 (void)write(*newsock, msg, strlen(msg)); 1226 close(*newsock); 1227 continue; 1228 } 1229 if (pipe(startup_p) == -1) { 1230 close(*newsock); 1231 continue; 1232 } 1233 1234 if (rexec_flag && socketpair(AF_UNIX, 1235 SOCK_STREAM, 0, config_s) == -1) { 1236 error("reexec socketpair: %s", 1237 strerror(errno)); 1238 close(*newsock); 1239 close(startup_p[0]); 1240 close(startup_p[1]); 1241 continue; 1242 } 1243 1244 for (j = 0; j < options.max_startups; j++) 1245 if (startup_pipes[j] == -1) { 1246 startup_pipes[j] = startup_p[0]; 1247 if (maxfd < startup_p[0]) 1248 maxfd = startup_p[0]; 1249 startups++; 1250 startup_flags[j] = 1; 1251 break; 1252 } 1253 1254 /* 1255 * Got connection. Fork a child to handle it, unless 1256 * we are in debugging mode. 1257 */ 1258 if (debug_flag) { 1259 /* 1260 * In debugging mode. Close the listening 1261 * socket, and start processing the 1262 * connection without forking. 1263 */ 1264 debug("Server will not fork when running in debugging mode."); 1265 close_listen_socks(); 1266 *sock_in = *newsock; 1267 *sock_out = *newsock; 1268 close(startup_p[0]); 1269 close(startup_p[1]); 1270 startup_pipe = -1; 1271 pid = getpid(); 1272 if (rexec_flag) { 1273 send_rexec_state(config_s[0], cfg); 1274 close(config_s[0]); 1275 } 1276 return; 1277 } 1278 1279 /* 1280 * Normal production daemon. Fork, and have 1281 * the child process the connection. The 1282 * parent continues listening. 1283 */ 1284 platform_pre_fork(); 1285 listening++; 1286 if ((pid = fork()) == 0) { 1287 /* 1288 * Child. Close the listening and 1289 * max_startup sockets. Start using 1290 * the accepted socket. Reinitialize 1291 * logging (since our pid has changed). 1292 * We return from this function to handle 1293 * the connection. 1294 */ 1295 platform_post_fork_child(); 1296 startup_pipe = startup_p[1]; 1297 close_startup_pipes(); 1298 close_listen_socks(); 1299 *sock_in = *newsock; 1300 *sock_out = *newsock; 1301 log_init(__progname, 1302 options.log_level, 1303 options.log_facility, 1304 log_stderr); 1305 if (rexec_flag) 1306 close(config_s[0]); 1307 else { 1308 /* 1309 * Signal parent that the preliminaries 1310 * for this child are complete. For the 1311 * re-exec case, this happens after the 1312 * child has received the rexec state 1313 * from the server. 1314 */ 1315 (void)atomicio(vwrite, startup_pipe, 1316 "\0", 1); 1317 } 1318 return; 1319 } 1320 1321 /* Parent. Stay in the loop. */ 1322 platform_post_fork_parent(pid); 1323 if (pid == -1) 1324 error("fork: %.100s", strerror(errno)); 1325 else 1326 debug("Forked child %ld.", (long)pid); 1327 1328 close(startup_p[1]); 1329 1330 if (rexec_flag) { 1331 send_rexec_state(config_s[0], cfg); 1332 close(config_s[0]); 1333 close(config_s[1]); 1334 } 1335 close(*newsock); 1336 1337 /* 1338 * Ensure that our random state differs 1339 * from that of the child 1340 */ 1341 arc4random_stir(); 1342 arc4random_buf(rnd, sizeof(rnd)); 1343 #ifdef WITH_OPENSSL 1344 RAND_seed(rnd, sizeof(rnd)); 1345 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1346 fatal("%s: RAND_bytes failed", __func__); 1347 #endif 1348 explicit_bzero(rnd, sizeof(rnd)); 1349 } 1350 } 1351 } 1352 1353 /* 1354 * If IP options are supported, make sure there are none (log and 1355 * return an error if any are found). Basically we are worried about 1356 * source routing; it can be used to pretend you are somebody 1357 * (ip-address) you are not. That itself may be "almost acceptable" 1358 * under certain circumstances, but rhosts authentication is useless 1359 * if source routing is accepted. Notice also that if we just dropped 1360 * source routing here, the other side could use IP spoofing to do 1361 * rest of the interaction and could still bypass security. So we 1362 * exit here if we detect any IP options. 1363 */ 1364 static void 1365 check_ip_options(struct ssh *ssh) 1366 { 1367 #ifdef IP_OPTIONS 1368 int sock_in = ssh_packet_get_connection_in(ssh); 1369 struct sockaddr_storage from; 1370 u_char opts[200]; 1371 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1372 char text[sizeof(opts) * 3 + 1]; 1373 1374 memset(&from, 0, sizeof(from)); 1375 if (getpeername(sock_in, (struct sockaddr *)&from, 1376 &fromlen) == -1) 1377 return; 1378 if (from.ss_family != AF_INET) 1379 return; 1380 /* XXX IPv6 options? */ 1381 1382 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1383 &option_size) >= 0 && option_size != 0) { 1384 text[0] = '\0'; 1385 for (i = 0; i < option_size; i++) 1386 snprintf(text + i*3, sizeof(text) - i*3, 1387 " %2.2x", opts[i]); 1388 fatal("Connection from %.100s port %d with IP opts: %.800s", 1389 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1390 } 1391 return; 1392 #endif /* IP_OPTIONS */ 1393 } 1394 1395 /* Set the routing domain for this process */ 1396 static void 1397 set_process_rdomain(struct ssh *ssh, const char *name) 1398 { 1399 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) 1400 if (name == NULL) 1401 return; /* default */ 1402 1403 if (strcmp(name, "%D") == 0) { 1404 /* "expands" to routing domain of connection */ 1405 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1406 return; 1407 } 1408 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ 1409 return sys_set_process_rdomain(name); 1410 #elif defined(__OpenBSD__) 1411 int rtable, ortable = getrtable(); 1412 const char *errstr; 1413 1414 if (name == NULL) 1415 return; /* default */ 1416 1417 if (strcmp(name, "%D") == 0) { 1418 /* "expands" to routing domain of connection */ 1419 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1420 return; 1421 } 1422 1423 rtable = (int)strtonum(name, 0, 255, &errstr); 1424 if (errstr != NULL) /* Shouldn't happen */ 1425 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1426 if (rtable != ortable && setrtable(rtable) != 0) 1427 fatal("Unable to set routing domain %d: %s", 1428 rtable, strerror(errno)); 1429 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1430 #else /* defined(__OpenBSD__) */ 1431 fatal("Unable to set routing domain: not supported in this platform"); 1432 #endif 1433 } 1434 1435 static void 1436 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1437 struct sshkey *key) 1438 { 1439 static struct ssh_digest_ctx *ctx; 1440 u_char *hash; 1441 size_t len; 1442 struct sshbuf *buf; 1443 int r; 1444 1445 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1446 fatal("%s: ssh_digest_start", __func__); 1447 if (key == NULL) { /* finalize */ 1448 /* add server config in case we are using agent for host keys */ 1449 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1450 sshbuf_len(server_cfg)) != 0) 1451 fatal("%s: ssh_digest_update", __func__); 1452 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1453 hash = xmalloc(len); 1454 if (ssh_digest_final(ctx, hash, len) != 0) 1455 fatal("%s: ssh_digest_final", __func__); 1456 options.timing_secret = PEEK_U64(hash); 1457 freezero(hash, len); 1458 ssh_digest_free(ctx); 1459 ctx = NULL; 1460 return; 1461 } 1462 if ((buf = sshbuf_new()) == NULL) 1463 fatal("%s could not allocate buffer", __func__); 1464 if ((r = sshkey_private_serialize(key, buf)) != 0) 1465 fatal("sshkey_private_serialize: %s", ssh_err(r)); 1466 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1467 fatal("%s: ssh_digest_update", __func__); 1468 sshbuf_reset(buf); 1469 sshbuf_free(buf); 1470 } 1471 1472 static char * 1473 prepare_proctitle(int ac, char **av) 1474 { 1475 char *ret = NULL; 1476 int i; 1477 1478 for (i = 0; i < ac; i++) 1479 xextendf(&ret, " ", "%s", av[i]); 1480 return ret; 1481 } 1482 1483 /* 1484 * Main program for the daemon. 1485 */ 1486 int 1487 main(int ac, char **av) 1488 { 1489 struct ssh *ssh = NULL; 1490 extern char *optarg; 1491 extern int optind; 1492 int r, opt, on = 1, already_daemon, remote_port; 1493 int sock_in = -1, sock_out = -1, newsock = -1; 1494 const char *remote_ip, *rdomain; 1495 char *fp, *line, *laddr, *logfile = NULL; 1496 int config_s[2] = { -1 , -1 }; 1497 u_int i, j; 1498 u_int64_t ibytes, obytes; 1499 mode_t new_umask; 1500 struct sshkey *key; 1501 struct sshkey *pubkey; 1502 int keytype; 1503 Authctxt *authctxt; 1504 struct connection_info *connection_info = NULL; 1505 1506 #ifdef HAVE_SECUREWARE 1507 (void)set_auth_parameters(ac, av); 1508 #endif 1509 __progname = ssh_get_progname(av[0]); 1510 1511 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1512 saved_argc = ac; 1513 rexec_argc = ac; 1514 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1515 for (i = 0; (int)i < ac; i++) 1516 saved_argv[i] = xstrdup(av[i]); 1517 saved_argv[i] = NULL; 1518 1519 #ifndef HAVE_SETPROCTITLE 1520 /* Prepare for later setproctitle emulation */ 1521 compat_init_setproctitle(ac, av); 1522 av = saved_argv; 1523 #endif 1524 1525 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1526 debug("setgroups(): %.200s", strerror(errno)); 1527 1528 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1529 sanitise_stdfd(); 1530 1531 seed_rng(); 1532 1533 /* Initialize configuration options to their default values. */ 1534 initialize_server_options(&options); 1535 1536 /* Parse command-line arguments. */ 1537 while ((opt = getopt(ac, av, 1538 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1539 switch (opt) { 1540 case '4': 1541 options.address_family = AF_INET; 1542 break; 1543 case '6': 1544 options.address_family = AF_INET6; 1545 break; 1546 case 'f': 1547 config_file_name = optarg; 1548 break; 1549 case 'c': 1550 servconf_add_hostcert("[command-line]", 0, 1551 &options, optarg); 1552 break; 1553 case 'd': 1554 if (debug_flag == 0) { 1555 debug_flag = 1; 1556 options.log_level = SYSLOG_LEVEL_DEBUG1; 1557 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1558 options.log_level++; 1559 break; 1560 case 'D': 1561 no_daemon_flag = 1; 1562 break; 1563 case 'E': 1564 logfile = optarg; 1565 /* FALLTHROUGH */ 1566 case 'e': 1567 log_stderr = 1; 1568 break; 1569 case 'i': 1570 inetd_flag = 1; 1571 break; 1572 case 'r': 1573 rexec_flag = 0; 1574 break; 1575 case 'R': 1576 rexeced_flag = 1; 1577 inetd_flag = 1; 1578 break; 1579 case 'Q': 1580 /* ignored */ 1581 break; 1582 case 'q': 1583 options.log_level = SYSLOG_LEVEL_QUIET; 1584 break; 1585 case 'b': 1586 /* protocol 1, ignored */ 1587 break; 1588 case 'p': 1589 options.ports_from_cmdline = 1; 1590 if (options.num_ports >= MAX_PORTS) { 1591 fprintf(stderr, "too many ports.\n"); 1592 exit(1); 1593 } 1594 options.ports[options.num_ports++] = a2port(optarg); 1595 if (options.ports[options.num_ports-1] <= 0) { 1596 fprintf(stderr, "Bad port number.\n"); 1597 exit(1); 1598 } 1599 break; 1600 case 'g': 1601 if ((options.login_grace_time = convtime(optarg)) == -1) { 1602 fprintf(stderr, "Invalid login grace time.\n"); 1603 exit(1); 1604 } 1605 break; 1606 case 'k': 1607 /* protocol 1, ignored */ 1608 break; 1609 case 'h': 1610 servconf_add_hostkey("[command-line]", 0, 1611 &options, optarg, 1); 1612 break; 1613 case 't': 1614 test_flag = 1; 1615 break; 1616 case 'T': 1617 test_flag = 2; 1618 break; 1619 case 'C': 1620 connection_info = get_connection_info(ssh, 0, 0); 1621 if (parse_server_match_testspec(connection_info, 1622 optarg) == -1) 1623 exit(1); 1624 break; 1625 case 'u': 1626 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1627 if (utmp_len > HOST_NAME_MAX+1) { 1628 fprintf(stderr, "Invalid utmp length.\n"); 1629 exit(1); 1630 } 1631 break; 1632 case 'o': 1633 line = xstrdup(optarg); 1634 if (process_server_config_line(&options, line, 1635 "command-line", 0, NULL, NULL, &includes) != 0) 1636 exit(1); 1637 free(line); 1638 break; 1639 case '?': 1640 default: 1641 usage(); 1642 break; 1643 } 1644 } 1645 if (rexeced_flag || inetd_flag) 1646 rexec_flag = 0; 1647 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1648 fatal("sshd re-exec requires execution with an absolute path"); 1649 if (rexeced_flag) 1650 closefrom(REEXEC_MIN_FREE_FD); 1651 else 1652 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1653 1654 /* If requested, redirect the logs to the specified logfile. */ 1655 if (logfile != NULL) 1656 log_redirect_stderr_to(logfile); 1657 /* 1658 * Force logging to stderr until we have loaded the private host 1659 * key (unless started from inetd) 1660 */ 1661 log_init(__progname, 1662 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1663 SYSLOG_LEVEL_INFO : options.log_level, 1664 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1665 SYSLOG_FACILITY_AUTH : options.log_facility, 1666 log_stderr || !inetd_flag || debug_flag); 1667 1668 /* 1669 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1670 * root's environment 1671 */ 1672 if (getenv("KRB5CCNAME") != NULL) 1673 (void) unsetenv("KRB5CCNAME"); 1674 1675 sensitive_data.have_ssh2_key = 0; 1676 1677 /* 1678 * If we're not doing an extended test do not silently ignore connection 1679 * test params. 1680 */ 1681 if (test_flag < 2 && connection_info != NULL) 1682 fatal("Config test connection parameter (-C) provided without " 1683 "test mode (-T)"); 1684 1685 /* Fetch our configuration */ 1686 if ((cfg = sshbuf_new()) == NULL) 1687 fatal("%s: sshbuf_new failed", __func__); 1688 if (rexeced_flag) { 1689 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1690 if (!debug_flag) { 1691 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1692 close(REEXEC_STARTUP_PIPE_FD); 1693 /* 1694 * Signal parent that this child is at a point where 1695 * they can go away if they have a SIGHUP pending. 1696 */ 1697 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1698 } 1699 } else if (strcasecmp(config_file_name, "none") != 0) 1700 load_server_config(config_file_name, cfg); 1701 1702 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1703 cfg, &includes, NULL); 1704 1705 /* Fill in default values for those options not explicitly set. */ 1706 fill_default_server_options(&options); 1707 1708 /* challenge-response is implemented via keyboard interactive */ 1709 if (options.challenge_response_authentication) 1710 options.kbd_interactive_authentication = 1; 1711 1712 /* Check that options are sensible */ 1713 if (options.authorized_keys_command_user == NULL && 1714 (options.authorized_keys_command != NULL && 1715 strcasecmp(options.authorized_keys_command, "none") != 0)) 1716 fatal("AuthorizedKeysCommand set without " 1717 "AuthorizedKeysCommandUser"); 1718 if (options.authorized_principals_command_user == NULL && 1719 (options.authorized_principals_command != NULL && 1720 strcasecmp(options.authorized_principals_command, "none") != 0)) 1721 fatal("AuthorizedPrincipalsCommand set without " 1722 "AuthorizedPrincipalsCommandUser"); 1723 1724 /* 1725 * Check whether there is any path through configured auth methods. 1726 * Unfortunately it is not possible to verify this generally before 1727 * daemonisation in the presence of Match block, but this catches 1728 * and warns for trivial misconfigurations that could break login. 1729 */ 1730 if (options.num_auth_methods != 0) { 1731 for (i = 0; i < options.num_auth_methods; i++) { 1732 if (auth2_methods_valid(options.auth_methods[i], 1733 1) == 0) 1734 break; 1735 } 1736 if (i >= options.num_auth_methods) 1737 fatal("AuthenticationMethods cannot be satisfied by " 1738 "enabled authentication methods"); 1739 } 1740 1741 /* Check that there are no remaining arguments. */ 1742 if (optind < ac) { 1743 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1744 exit(1); 1745 } 1746 1747 debug("sshd version %s, %s", SSH_VERSION, 1748 #ifdef WITH_OPENSSL 1749 OpenSSL_version(OPENSSL_VERSION) 1750 #else 1751 "without OpenSSL" 1752 #endif 1753 ); 1754 1755 /* Store privilege separation user for later use if required. */ 1756 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); 1757 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1758 if (privsep_chroot || options.kerberos_authentication) 1759 fatal("Privilege separation user %s does not exist", 1760 SSH_PRIVSEP_USER); 1761 } else { 1762 privsep_pw = pwcopy(privsep_pw); 1763 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); 1764 privsep_pw->pw_passwd = xstrdup("*"); 1765 } 1766 endpwent(); 1767 1768 /* load host keys */ 1769 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1770 sizeof(struct sshkey *)); 1771 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1772 sizeof(struct sshkey *)); 1773 1774 if (options.host_key_agent) { 1775 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1776 setenv(SSH_AUTHSOCKET_ENV_NAME, 1777 options.host_key_agent, 1); 1778 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1779 have_agent = 1; 1780 else 1781 error("Could not connect to agent \"%s\": %s", 1782 options.host_key_agent, ssh_err(r)); 1783 } 1784 1785 for (i = 0; i < options.num_host_key_files; i++) { 1786 int ll = options.host_key_file_userprovided[i] ? 1787 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1788 1789 if (options.host_key_files[i] == NULL) 1790 continue; 1791 if ((r = sshkey_load_private(options.host_key_files[i], "", 1792 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1793 do_log2(ll, "Unable to load host key \"%s\": %s", 1794 options.host_key_files[i], ssh_err(r)); 1795 if (sshkey_is_sk(key) && 1796 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1797 debug("host key %s requires user presence, ignoring", 1798 options.host_key_files[i]); 1799 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1800 } 1801 if (r == 0 && key != NULL && 1802 (r = sshkey_shield_private(key)) != 0) { 1803 do_log2(ll, "Unable to shield host key \"%s\": %s", 1804 options.host_key_files[i], ssh_err(r)); 1805 sshkey_free(key); 1806 key = NULL; 1807 } 1808 if ((r = sshkey_load_public(options.host_key_files[i], 1809 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1810 do_log2(ll, "Unable to load host key \"%s\": %s", 1811 options.host_key_files[i], ssh_err(r)); 1812 if (pubkey == NULL && key != NULL) 1813 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1814 fatal("Could not demote key: \"%s\": %s", 1815 options.host_key_files[i], ssh_err(r)); 1816 sensitive_data.host_keys[i] = key; 1817 sensitive_data.host_pubkeys[i] = pubkey; 1818 1819 if (key == NULL && pubkey != NULL && have_agent) { 1820 debug("will rely on agent for hostkey %s", 1821 options.host_key_files[i]); 1822 keytype = pubkey->type; 1823 } else if (key != NULL) { 1824 keytype = key->type; 1825 accumulate_host_timing_secret(cfg, key); 1826 } else { 1827 do_log2(ll, "Unable to load host key: %s", 1828 options.host_key_files[i]); 1829 sensitive_data.host_keys[i] = NULL; 1830 sensitive_data.host_pubkeys[i] = NULL; 1831 continue; 1832 } 1833 1834 switch (keytype) { 1835 case KEY_RSA: 1836 case KEY_DSA: 1837 case KEY_ECDSA: 1838 case KEY_ED25519: 1839 case KEY_ECDSA_SK: 1840 case KEY_ED25519_SK: 1841 case KEY_XMSS: 1842 if (have_agent || key != NULL) 1843 sensitive_data.have_ssh2_key = 1; 1844 break; 1845 } 1846 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1847 SSH_FP_DEFAULT)) == NULL) 1848 fatal("sshkey_fingerprint failed"); 1849 debug("%s host key #%d: %s %s", 1850 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1851 free(fp); 1852 } 1853 accumulate_host_timing_secret(cfg, NULL); 1854 if (!sensitive_data.have_ssh2_key) { 1855 logit("sshd: no hostkeys available -- exiting."); 1856 exit(1); 1857 } 1858 1859 /* 1860 * Load certificates. They are stored in an array at identical 1861 * indices to the public keys that they relate to. 1862 */ 1863 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1864 sizeof(struct sshkey *)); 1865 for (i = 0; i < options.num_host_key_files; i++) 1866 sensitive_data.host_certificates[i] = NULL; 1867 1868 for (i = 0; i < options.num_host_cert_files; i++) { 1869 if (options.host_cert_files[i] == NULL) 1870 continue; 1871 if ((r = sshkey_load_public(options.host_cert_files[i], 1872 &key, NULL)) != 0) { 1873 error("Could not load host certificate \"%s\": %s", 1874 options.host_cert_files[i], ssh_err(r)); 1875 continue; 1876 } 1877 if (!sshkey_is_cert(key)) { 1878 error("Certificate file is not a certificate: %s", 1879 options.host_cert_files[i]); 1880 sshkey_free(key); 1881 continue; 1882 } 1883 /* Find matching private key */ 1884 for (j = 0; j < options.num_host_key_files; j++) { 1885 if (sshkey_equal_public(key, 1886 sensitive_data.host_keys[j])) { 1887 sensitive_data.host_certificates[j] = key; 1888 break; 1889 } 1890 } 1891 if (j >= options.num_host_key_files) { 1892 error("No matching private key for certificate: %s", 1893 options.host_cert_files[i]); 1894 sshkey_free(key); 1895 continue; 1896 } 1897 sensitive_data.host_certificates[j] = key; 1898 debug("host certificate: #%u type %d %s", j, key->type, 1899 sshkey_type(key)); 1900 } 1901 1902 if (privsep_chroot) { 1903 struct stat st; 1904 1905 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1906 (S_ISDIR(st.st_mode) == 0)) 1907 fatal("Missing privilege separation directory: %s", 1908 _PATH_PRIVSEP_CHROOT_DIR); 1909 1910 #ifdef HAVE_CYGWIN 1911 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1912 (st.st_uid != getuid () || 1913 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1914 #else 1915 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1916 #endif 1917 fatal("%s must be owned by root and not group or " 1918 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1919 } 1920 1921 if (test_flag > 1) { 1922 /* 1923 * If no connection info was provided by -C then use 1924 * use a blank one that will cause no predicate to match. 1925 */ 1926 if (connection_info == NULL) 1927 connection_info = get_connection_info(ssh, 0, 0); 1928 connection_info->test = 1; 1929 parse_server_match_config(&options, &includes, connection_info); 1930 dump_config(&options); 1931 } 1932 1933 /* Configuration looks good, so exit if in test mode. */ 1934 if (test_flag) 1935 exit(0); 1936 1937 /* 1938 * Clear out any supplemental groups we may have inherited. This 1939 * prevents inadvertent creation of files with bad modes (in the 1940 * portable version at least, it's certainly possible for PAM 1941 * to create a file, and we can't control the code in every 1942 * module which might be used). 1943 */ 1944 if (setgroups(0, NULL) < 0) 1945 debug("setgroups() failed: %.200s", strerror(errno)); 1946 1947 if (rexec_flag) { 1948 if (rexec_argc < 0) 1949 fatal("rexec_argc %d < 0", rexec_argc); 1950 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1951 for (i = 0; i < (u_int)rexec_argc; i++) { 1952 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1953 rexec_argv[i] = saved_argv[i]; 1954 } 1955 rexec_argv[rexec_argc] = "-R"; 1956 rexec_argv[rexec_argc + 1] = NULL; 1957 } 1958 listener_proctitle = prepare_proctitle(ac, av); 1959 1960 /* Ensure that umask disallows at least group and world write */ 1961 new_umask = umask(0077) | 0022; 1962 (void) umask(new_umask); 1963 1964 /* Initialize the log (it is reinitialized below in case we forked). */ 1965 if (debug_flag && (!inetd_flag || rexeced_flag)) 1966 log_stderr = 1; 1967 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1968 1969 /* 1970 * If not in debugging mode, not started from inetd and not already 1971 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1972 * terminal, and fork. The original process exits. 1973 */ 1974 already_daemon = daemonized(); 1975 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1976 1977 if (daemon(0, 0) == -1) 1978 fatal("daemon() failed: %.200s", strerror(errno)); 1979 1980 disconnect_controlling_tty(); 1981 } 1982 /* Reinitialize the log (because of the fork above). */ 1983 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1984 1985 /* Chdir to the root directory so that the current disk can be 1986 unmounted if desired. */ 1987 if (chdir("/") == -1) 1988 error("chdir(\"/\"): %s", strerror(errno)); 1989 1990 /* ignore SIGPIPE */ 1991 ssh_signal(SIGPIPE, SIG_IGN); 1992 1993 /* Get a connection, either from inetd or a listening TCP socket */ 1994 if (inetd_flag) { 1995 server_accept_inetd(&sock_in, &sock_out); 1996 } else { 1997 platform_pre_listen(); 1998 server_listen(); 1999 2000 ssh_signal(SIGHUP, sighup_handler); 2001 ssh_signal(SIGCHLD, main_sigchld_handler); 2002 ssh_signal(SIGTERM, sigterm_handler); 2003 ssh_signal(SIGQUIT, sigterm_handler); 2004 2005 /* 2006 * Write out the pid file after the sigterm handler 2007 * is setup and the listen sockets are bound 2008 */ 2009 if (options.pid_file != NULL && !debug_flag) { 2010 FILE *f = fopen(options.pid_file, "w"); 2011 2012 if (f == NULL) { 2013 error("Couldn't create pid file \"%s\": %s", 2014 options.pid_file, strerror(errno)); 2015 } else { 2016 fprintf(f, "%ld\n", (long) getpid()); 2017 fclose(f); 2018 } 2019 } 2020 2021 /* Accept a connection and return in a forked child */ 2022 server_accept_loop(&sock_in, &sock_out, 2023 &newsock, config_s); 2024 } 2025 2026 /* This is the child processing a new connection. */ 2027 setproctitle("%s", "[accepted]"); 2028 2029 /* 2030 * Create a new session and process group since the 4.4BSD 2031 * setlogin() affects the entire process group. We don't 2032 * want the child to be able to affect the parent. 2033 */ 2034 #if !defined(SSHD_ACQUIRES_CTTY) 2035 /* 2036 * If setsid is called, on some platforms sshd will later acquire a 2037 * controlling terminal which will result in "could not set 2038 * controlling tty" errors. 2039 */ 2040 if (!debug_flag && !inetd_flag && setsid() == -1) 2041 error("setsid: %.100s", strerror(errno)); 2042 #endif 2043 2044 if (rexec_flag) { 2045 int fd; 2046 2047 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2048 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2049 dup2(newsock, STDIN_FILENO); 2050 dup2(STDIN_FILENO, STDOUT_FILENO); 2051 if (startup_pipe == -1) 2052 close(REEXEC_STARTUP_PIPE_FD); 2053 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2054 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2055 close(startup_pipe); 2056 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2057 } 2058 2059 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2060 close(config_s[1]); 2061 2062 execv(rexec_argv[0], rexec_argv); 2063 2064 /* Reexec has failed, fall back and continue */ 2065 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2066 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2067 log_init(__progname, options.log_level, 2068 options.log_facility, log_stderr); 2069 2070 /* Clean up fds */ 2071 close(REEXEC_CONFIG_PASS_FD); 2072 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2073 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2074 dup2(fd, STDIN_FILENO); 2075 dup2(fd, STDOUT_FILENO); 2076 if (fd > STDERR_FILENO) 2077 close(fd); 2078 } 2079 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2080 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2081 } 2082 2083 /* Executed child processes don't need these. */ 2084 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2085 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2086 2087 /* We will not restart on SIGHUP since it no longer makes sense. */ 2088 ssh_signal(SIGALRM, SIG_DFL); 2089 ssh_signal(SIGHUP, SIG_DFL); 2090 ssh_signal(SIGTERM, SIG_DFL); 2091 ssh_signal(SIGQUIT, SIG_DFL); 2092 ssh_signal(SIGCHLD, SIG_DFL); 2093 ssh_signal(SIGINT, SIG_DFL); 2094 2095 /* 2096 * Register our connection. This turns encryption off because we do 2097 * not have a key. 2098 */ 2099 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2100 fatal("Unable to create connection"); 2101 the_active_state = ssh; 2102 ssh_packet_set_server(ssh); 2103 2104 check_ip_options(ssh); 2105 2106 /* Prepare the channels layer */ 2107 channel_init_channels(ssh); 2108 channel_set_af(ssh, options.address_family); 2109 process_permitopen(ssh, &options); 2110 2111 /* Set SO_KEEPALIVE if requested. */ 2112 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2113 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2114 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2115 2116 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2117 debug("ssh_remote_port failed"); 2118 cleanup_exit(255); 2119 } 2120 2121 if (options.routing_domain != NULL) 2122 set_process_rdomain(ssh, options.routing_domain); 2123 2124 /* 2125 * The rest of the code depends on the fact that 2126 * ssh_remote_ipaddr() caches the remote ip, even if 2127 * the socket goes away. 2128 */ 2129 remote_ip = ssh_remote_ipaddr(ssh); 2130 2131 #ifdef SSH_AUDIT_EVENTS 2132 audit_connection_from(remote_ip, remote_port); 2133 #endif 2134 2135 rdomain = ssh_packet_rdomain_in(ssh); 2136 2137 /* Log the connection. */ 2138 laddr = get_local_ipaddr(sock_in); 2139 verbose("Connection from %s port %d on %s port %d%s%s%s", 2140 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2141 rdomain == NULL ? "" : " rdomain \"", 2142 rdomain == NULL ? "" : rdomain, 2143 rdomain == NULL ? "" : "\""); 2144 free(laddr); 2145 2146 /* 2147 * We don't want to listen forever unless the other side 2148 * successfully authenticates itself. So we set up an alarm which is 2149 * cleared after successful authentication. A limit of zero 2150 * indicates no limit. Note that we don't set the alarm in debugging 2151 * mode; it is just annoying to have the server exit just when you 2152 * are about to discover the bug. 2153 */ 2154 ssh_signal(SIGALRM, grace_alarm_handler); 2155 if (!debug_flag) 2156 alarm(options.login_grace_time); 2157 2158 if ((r = kex_exchange_identification(ssh, -1, 2159 options.version_addendum)) != 0) 2160 sshpkt_fatal(ssh, r, "banner exchange"); 2161 2162 ssh_packet_set_nonblocking(ssh); 2163 2164 /* allocate authentication context */ 2165 authctxt = xcalloc(1, sizeof(*authctxt)); 2166 ssh->authctxt = authctxt; 2167 2168 authctxt->loginmsg = loginmsg; 2169 2170 /* XXX global for cleanup, access from other modules */ 2171 the_authctxt = authctxt; 2172 2173 /* Set default key authentication options */ 2174 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2175 fatal("allocation failed"); 2176 2177 /* prepare buffer to collect messages to display to user after login */ 2178 if ((loginmsg = sshbuf_new()) == NULL) 2179 fatal("%s: sshbuf_new failed", __func__); 2180 auth_debug_reset(); 2181 2182 if (use_privsep) { 2183 if (privsep_preauth(ssh) == 1) 2184 goto authenticated; 2185 } else if (have_agent) { 2186 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2187 error("Unable to get agent socket: %s", ssh_err(r)); 2188 have_agent = 0; 2189 } 2190 } 2191 2192 /* perform the key exchange */ 2193 /* authenticate user and start session */ 2194 do_ssh2_kex(ssh); 2195 do_authentication2(ssh); 2196 2197 /* 2198 * If we use privilege separation, the unprivileged child transfers 2199 * the current keystate and exits 2200 */ 2201 if (use_privsep) { 2202 mm_send_keystate(ssh, pmonitor); 2203 ssh_packet_clear_keys(ssh); 2204 exit(0); 2205 } 2206 2207 authenticated: 2208 /* 2209 * Cancel the alarm we set to limit the time taken for 2210 * authentication. 2211 */ 2212 alarm(0); 2213 ssh_signal(SIGALRM, SIG_DFL); 2214 authctxt->authenticated = 1; 2215 if (startup_pipe != -1) { 2216 close(startup_pipe); 2217 startup_pipe = -1; 2218 } 2219 2220 #ifdef SSH_AUDIT_EVENTS 2221 audit_event(ssh, SSH_AUTH_SUCCESS); 2222 #endif 2223 2224 #ifdef GSSAPI 2225 if (options.gss_authentication) { 2226 temporarily_use_uid(authctxt->pw); 2227 ssh_gssapi_storecreds(); 2228 restore_uid(); 2229 } 2230 #endif 2231 #ifdef USE_PAM 2232 if (options.use_pam) { 2233 do_pam_setcred(1); 2234 do_pam_session(ssh); 2235 } 2236 #endif 2237 2238 /* 2239 * In privilege separation, we fork another child and prepare 2240 * file descriptor passing. 2241 */ 2242 if (use_privsep) { 2243 privsep_postauth(ssh, authctxt); 2244 /* the monitor process [priv] will not return */ 2245 } 2246 2247 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2248 options.client_alive_count_max); 2249 2250 /* Try to send all our hostkeys to the client */ 2251 notify_hostkeys(ssh); 2252 2253 /* Start session. */ 2254 do_authenticated(ssh, authctxt); 2255 2256 /* The connection has been terminated. */ 2257 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2258 verbose("Transferred: sent %llu, received %llu bytes", 2259 (unsigned long long)obytes, (unsigned long long)ibytes); 2260 2261 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2262 2263 #ifdef USE_PAM 2264 if (options.use_pam) 2265 finish_pam(); 2266 #endif /* USE_PAM */ 2267 2268 #ifdef SSH_AUDIT_EVENTS 2269 PRIVSEP(audit_event(ssh, SSH_CONNECTION_CLOSE)); 2270 #endif 2271 2272 ssh_packet_close(ssh); 2273 2274 if (use_privsep) 2275 mm_terminate(); 2276 2277 exit(0); 2278 } 2279 2280 int 2281 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2282 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2283 const u_char *data, size_t dlen, const char *alg) 2284 { 2285 int r; 2286 2287 if (use_privsep) { 2288 if (privkey) { 2289 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2290 data, dlen, alg, options.sk_provider, 2291 ssh->compat) < 0) 2292 fatal("%s: privkey sign failed", __func__); 2293 } else { 2294 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2295 data, dlen, alg, options.sk_provider, 2296 ssh->compat) < 0) 2297 fatal("%s: pubkey sign failed", __func__); 2298 } 2299 } else { 2300 if (privkey) { 2301 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2302 alg, options.sk_provider, ssh->compat) < 0) 2303 fatal("%s: privkey sign failed", __func__); 2304 } else { 2305 if ((r = ssh_agent_sign(auth_sock, pubkey, 2306 signature, slenp, data, dlen, alg, 2307 ssh->compat)) != 0) { 2308 fatal("%s: agent sign failed: %s", 2309 __func__, ssh_err(r)); 2310 } 2311 } 2312 } 2313 return 0; 2314 } 2315 2316 /* SSH2 key exchange */ 2317 static void 2318 do_ssh2_kex(struct ssh *ssh) 2319 { 2320 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2321 struct kex *kex; 2322 int r; 2323 2324 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2325 options.kex_algorithms); 2326 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2327 options.ciphers); 2328 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2329 options.ciphers); 2330 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2331 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2332 2333 if (options.compression == COMP_NONE) { 2334 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2335 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2336 } 2337 2338 if (options.rekey_limit || options.rekey_interval) 2339 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2340 options.rekey_interval); 2341 2342 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2343 list_hostkey_types()); 2344 2345 /* start key exchange */ 2346 if ((r = kex_setup(ssh, myproposal)) != 0) 2347 fatal("kex_setup: %s", ssh_err(r)); 2348 kex = ssh->kex; 2349 #ifdef WITH_OPENSSL 2350 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2351 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2352 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2353 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2354 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2355 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2356 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2357 # ifdef OPENSSL_HAS_ECC 2358 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2359 # endif 2360 #endif 2361 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2362 kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server; 2363 kex->load_host_public_key=&get_hostkey_public_by_type; 2364 kex->load_host_private_key=&get_hostkey_private_by_type; 2365 kex->host_key_index=&get_hostkey_index; 2366 kex->sign = sshd_hostkey_sign; 2367 2368 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2369 2370 session_id2 = kex->session_id; 2371 session_id2_len = kex->session_id_len; 2372 2373 #ifdef DEBUG_KEXDH 2374 /* send 1st encrypted/maced/compressed message */ 2375 packet_start(SSH2_MSG_IGNORE); 2376 packet_put_cstring("markus"); 2377 packet_send(); 2378 packet_write_wait(); 2379 #endif 2380 debug("KEX done"); 2381 } 2382 2383 /* server specific fatal cleanup */ 2384 void 2385 cleanup_exit(int i) 2386 { 2387 if (the_active_state != NULL && the_authctxt != NULL) { 2388 do_cleanup(the_active_state, the_authctxt); 2389 if (use_privsep && privsep_is_preauth && 2390 pmonitor != NULL && pmonitor->m_pid > 1) { 2391 debug("Killing privsep child %d", pmonitor->m_pid); 2392 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2393 errno != ESRCH) 2394 error("%s: kill(%d): %s", __func__, 2395 pmonitor->m_pid, strerror(errno)); 2396 } 2397 } 2398 #ifdef SSH_AUDIT_EVENTS 2399 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2400 if (the_active_state != NULL && (!use_privsep || mm_is_monitor())) 2401 audit_event(the_active_state, SSH_CONNECTION_ABANDON); 2402 #endif 2403 _exit(i); 2404 } 2405