1 /* $OpenBSD: sshd.c,v 1.516 2018/09/21 12:23:17 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 __RCSID("$FreeBSD$"); 47 48 #include <sys/types.h> 49 #include <sys/ioctl.h> 50 #include <sys/mman.h> 51 #include <sys/socket.h> 52 #ifdef HAVE_SYS_STAT_H 53 # include <sys/stat.h> 54 #endif 55 #ifdef HAVE_SYS_TIME_H 56 # include <sys/time.h> 57 #endif 58 #include "openbsd-compat/sys-tree.h" 59 #include "openbsd-compat/sys-queue.h" 60 #include <sys/wait.h> 61 62 #include <errno.h> 63 #include <fcntl.h> 64 #include <netdb.h> 65 #ifdef HAVE_PATHS_H 66 #include <paths.h> 67 #endif 68 #include <grp.h> 69 #include <pwd.h> 70 #include <signal.h> 71 #include <stdarg.h> 72 #include <stdio.h> 73 #include <stdlib.h> 74 #include <string.h> 75 #include <unistd.h> 76 #include <limits.h> 77 78 #ifdef WITH_OPENSSL 79 #include <openssl/dh.h> 80 #include <openssl/bn.h> 81 #include <openssl/rand.h> 82 #include "openbsd-compat/openssl-compat.h" 83 #endif 84 85 #ifdef HAVE_SECUREWARE 86 #include <sys/security.h> 87 #include <prot.h> 88 #endif 89 90 #ifdef __FreeBSD__ 91 #include <resolv.h> 92 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 93 #include <gssapi/gssapi.h> 94 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 95 #include <gssapi.h> 96 #endif 97 #endif 98 99 #include "xmalloc.h" 100 #include "ssh.h" 101 #include "ssh2.h" 102 #include "sshpty.h" 103 #include "packet.h" 104 #include "log.h" 105 #include "sshbuf.h" 106 #include "misc.h" 107 #include "match.h" 108 #include "servconf.h" 109 #include "uidswap.h" 110 #include "compat.h" 111 #include "cipher.h" 112 #include "digest.h" 113 #include "sshkey.h" 114 #include "kex.h" 115 #include "myproposal.h" 116 #include "authfile.h" 117 #include "pathnames.h" 118 #include "atomicio.h" 119 #include "canohost.h" 120 #include "hostfile.h" 121 #include "auth.h" 122 #include "authfd.h" 123 #include "msg.h" 124 #include "dispatch.h" 125 #include "channels.h" 126 #include "session.h" 127 #include "monitor.h" 128 #ifdef GSSAPI 129 #include "ssh-gss.h" 130 #endif 131 #include "monitor_wrap.h" 132 #include "ssh-sandbox.h" 133 #include "auth-options.h" 134 #include "version.h" 135 #include "ssherr.h" 136 #include "blacklist_client.h" 137 138 #ifdef LIBWRAP 139 #include <tcpd.h> 140 #include <syslog.h> 141 int allow_severity; 142 int deny_severity; 143 #endif /* LIBWRAP */ 144 145 /* Re-exec fds */ 146 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 147 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 148 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 149 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 150 151 extern char *__progname; 152 153 /* Server configuration options. */ 154 ServerOptions options; 155 156 /* Name of the server configuration file. */ 157 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 158 159 /* 160 * Debug mode flag. This can be set on the command line. If debug 161 * mode is enabled, extra debugging output will be sent to the system 162 * log, the daemon will not go to background, and will exit after processing 163 * the first connection. 164 */ 165 int debug_flag = 0; 166 167 /* 168 * Indicating that the daemon should only test the configuration and keys. 169 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 170 * configuration, optionally using connection information provided by the 171 * "-C" flag. 172 */ 173 int test_flag = 0; 174 175 /* Flag indicating that the daemon is being started from inetd. */ 176 int inetd_flag = 0; 177 178 /* Flag indicating that sshd should not detach and become a daemon. */ 179 int no_daemon_flag = 0; 180 181 /* debug goes to stderr unless inetd_flag is set */ 182 int log_stderr = 0; 183 184 /* Saved arguments to main(). */ 185 char **saved_argv; 186 int saved_argc; 187 188 /* re-exec */ 189 int rexeced_flag = 0; 190 int rexec_flag = 1; 191 int rexec_argc = 0; 192 char **rexec_argv; 193 194 /* 195 * The sockets that the server is listening; this is used in the SIGHUP 196 * signal handler. 197 */ 198 #define MAX_LISTEN_SOCKS 16 199 int listen_socks[MAX_LISTEN_SOCKS]; 200 int num_listen_socks = 0; 201 202 /* 203 * the client's version string, passed by sshd2 in compat mode. if != NULL, 204 * sshd will skip the version-number exchange 205 */ 206 char *client_version_string = NULL; 207 char *server_version_string = NULL; 208 209 /* Daemon's agent connection */ 210 int auth_sock = -1; 211 int have_agent = 0; 212 213 /* 214 * Any really sensitive data in the application is contained in this 215 * structure. The idea is that this structure could be locked into memory so 216 * that the pages do not get written into swap. However, there are some 217 * problems. The private key contains BIGNUMs, and we do not (in principle) 218 * have access to the internals of them, and locking just the structure is 219 * not very useful. Currently, memory locking is not implemented. 220 */ 221 struct { 222 struct sshkey **host_keys; /* all private host keys */ 223 struct sshkey **host_pubkeys; /* all public host keys */ 224 struct sshkey **host_certificates; /* all public host certificates */ 225 int have_ssh2_key; 226 } sensitive_data; 227 228 /* This is set to true when a signal is received. */ 229 static volatile sig_atomic_t received_sighup = 0; 230 static volatile sig_atomic_t received_sigterm = 0; 231 232 /* session identifier, used by RSA-auth */ 233 u_char session_id[16]; 234 235 /* same for ssh2 */ 236 u_char *session_id2 = NULL; 237 u_int session_id2_len = 0; 238 239 /* record remote hostname or ip */ 240 u_int utmp_len = HOST_NAME_MAX+1; 241 242 /* options.max_startup sized array of fd ints */ 243 int *startup_pipes = NULL; 244 int startup_pipe; /* in child */ 245 246 /* variables used for privilege separation */ 247 int use_privsep = -1; 248 struct monitor *pmonitor = NULL; 249 int privsep_is_preauth = 1; 250 static int privsep_chroot = 1; 251 252 /* global authentication context */ 253 Authctxt *the_authctxt = NULL; 254 255 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 256 struct sshauthopt *auth_opts = NULL; 257 258 /* sshd_config buffer */ 259 struct sshbuf *cfg; 260 261 /* message to be displayed after login */ 262 struct sshbuf *loginmsg; 263 264 /* Unprivileged user */ 265 struct passwd *privsep_pw = NULL; 266 267 /* Prototypes for various functions defined later in this file. */ 268 void destroy_sensitive_data(void); 269 void demote_sensitive_data(void); 270 static void do_ssh2_kex(void); 271 272 /* 273 * Close all listening sockets 274 */ 275 static void 276 close_listen_socks(void) 277 { 278 int i; 279 280 for (i = 0; i < num_listen_socks; i++) 281 close(listen_socks[i]); 282 num_listen_socks = -1; 283 } 284 285 static void 286 close_startup_pipes(void) 287 { 288 int i; 289 290 if (startup_pipes) 291 for (i = 0; i < options.max_startups; i++) 292 if (startup_pipes[i] != -1) 293 close(startup_pipes[i]); 294 } 295 296 /* 297 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 298 * the effect is to reread the configuration file (and to regenerate 299 * the server key). 300 */ 301 302 /*ARGSUSED*/ 303 static void 304 sighup_handler(int sig) 305 { 306 int save_errno = errno; 307 308 received_sighup = 1; 309 errno = save_errno; 310 } 311 312 /* 313 * Called from the main program after receiving SIGHUP. 314 * Restarts the server. 315 */ 316 static void 317 sighup_restart(void) 318 { 319 logit("Received SIGHUP; restarting."); 320 if (options.pid_file != NULL) 321 unlink(options.pid_file); 322 platform_pre_restart(); 323 close_listen_socks(); 324 close_startup_pipes(); 325 alarm(0); /* alarm timer persists across exec */ 326 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 327 execv(saved_argv[0], saved_argv); 328 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 329 strerror(errno)); 330 exit(1); 331 } 332 333 /* 334 * Generic signal handler for terminating signals in the master daemon. 335 */ 336 /*ARGSUSED*/ 337 static void 338 sigterm_handler(int sig) 339 { 340 received_sigterm = sig; 341 } 342 343 /* 344 * SIGCHLD handler. This is called whenever a child dies. This will then 345 * reap any zombies left by exited children. 346 */ 347 /*ARGSUSED*/ 348 static void 349 main_sigchld_handler(int sig) 350 { 351 int save_errno = errno; 352 pid_t pid; 353 int status; 354 355 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 356 (pid < 0 && errno == EINTR)) 357 ; 358 errno = save_errno; 359 } 360 361 /* 362 * Signal handler for the alarm after the login grace period has expired. 363 */ 364 /*ARGSUSED*/ 365 static void 366 grace_alarm_handler(int sig) 367 { 368 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 369 kill(pmonitor->m_pid, SIGALRM); 370 371 /* 372 * Try to kill any processes that we have spawned, E.g. authorized 373 * keys command helpers. 374 */ 375 if (getpgid(0) == getpid()) { 376 signal(SIGTERM, SIG_IGN); 377 kill(0, SIGTERM); 378 } 379 380 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 381 382 /* Log error and exit. */ 383 sigdie("Timeout before authentication for %s port %d", 384 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state)); 385 } 386 387 static void 388 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) 389 { 390 u_int i; 391 int remote_major, remote_minor; 392 char *s; 393 char buf[256]; /* Must not be larger than remote_version. */ 394 char remote_version[256]; /* Must be at least as big as buf. */ 395 396 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n", 397 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION, 398 *options.version_addendum == '\0' ? "" : " ", 399 options.version_addendum); 400 401 /* Send our protocol version identification. */ 402 if (atomicio(vwrite, sock_out, server_version_string, 403 strlen(server_version_string)) 404 != strlen(server_version_string)) { 405 logit("Could not write ident string to %s port %d", 406 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 407 cleanup_exit(255); 408 } 409 410 /* Read other sides version identification. */ 411 memset(buf, 0, sizeof(buf)); 412 for (i = 0; i < sizeof(buf) - 1; i++) { 413 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 414 logit("Did not receive identification string " 415 "from %s port %d", 416 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 417 cleanup_exit(255); 418 } 419 if (buf[i] == '\r') { 420 buf[i] = 0; 421 /* Kludge for F-Secure Macintosh < 1.0.2 */ 422 if (i == 12 && 423 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 424 break; 425 continue; 426 } 427 if (buf[i] == '\n') { 428 buf[i] = 0; 429 break; 430 } 431 } 432 buf[sizeof(buf) - 1] = 0; 433 client_version_string = xstrdup(buf); 434 435 /* 436 * Check that the versions match. In future this might accept 437 * several versions and set appropriate flags to handle them. 438 */ 439 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 440 &remote_major, &remote_minor, remote_version) != 3) { 441 s = "Protocol mismatch.\n"; 442 (void) atomicio(vwrite, sock_out, s, strlen(s)); 443 logit("Bad protocol version identification '%.100s' " 444 "from %s port %d", client_version_string, 445 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 446 close(sock_in); 447 close(sock_out); 448 cleanup_exit(255); 449 } 450 debug("Client protocol version %d.%d; client software version %.100s", 451 remote_major, remote_minor, remote_version); 452 453 ssh->compat = compat_datafellows(remote_version); 454 455 if ((ssh->compat & SSH_BUG_PROBE) != 0) { 456 logit("probed from %s port %d with %s. Don't panic.", 457 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 458 client_version_string); 459 cleanup_exit(255); 460 } 461 if ((ssh->compat & SSH_BUG_SCANNER) != 0) { 462 logit("scanned from %s port %d with %s. Don't panic.", 463 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 464 client_version_string); 465 cleanup_exit(255); 466 } 467 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 468 logit("Client version \"%.100s\" uses unsafe RSA signature " 469 "scheme; disabling use of RSA keys", remote_version); 470 } 471 472 chop(server_version_string); 473 debug("Local version string %.200s", server_version_string); 474 475 if (remote_major != 2 && 476 !(remote_major == 1 && remote_minor == 99)) { 477 s = "Protocol major versions differ.\n"; 478 (void) atomicio(vwrite, sock_out, s, strlen(s)); 479 close(sock_in); 480 close(sock_out); 481 logit("Protocol major versions differ for %s port %d: " 482 "%.200s vs. %.200s", 483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 484 server_version_string, client_version_string); 485 cleanup_exit(255); 486 } 487 } 488 489 /* Destroy the host and server keys. They will no longer be needed. */ 490 void 491 destroy_sensitive_data(void) 492 { 493 u_int i; 494 495 for (i = 0; i < options.num_host_key_files; i++) { 496 if (sensitive_data.host_keys[i]) { 497 sshkey_free(sensitive_data.host_keys[i]); 498 sensitive_data.host_keys[i] = NULL; 499 } 500 if (sensitive_data.host_certificates[i]) { 501 sshkey_free(sensitive_data.host_certificates[i]); 502 sensitive_data.host_certificates[i] = NULL; 503 } 504 } 505 } 506 507 /* Demote private to public keys for network child */ 508 void 509 demote_sensitive_data(void) 510 { 511 struct sshkey *tmp; 512 u_int i; 513 int r; 514 515 for (i = 0; i < options.num_host_key_files; i++) { 516 if (sensitive_data.host_keys[i]) { 517 if ((r = sshkey_from_private( 518 sensitive_data.host_keys[i], &tmp)) != 0) 519 fatal("could not demote host %s key: %s", 520 sshkey_type(sensitive_data.host_keys[i]), 521 ssh_err(r)); 522 sshkey_free(sensitive_data.host_keys[i]); 523 sensitive_data.host_keys[i] = tmp; 524 } 525 /* Certs do not need demotion */ 526 } 527 } 528 529 static void 530 reseed_prngs(void) 531 { 532 u_int32_t rnd[256]; 533 534 #ifdef WITH_OPENSSL 535 RAND_poll(); 536 #endif 537 arc4random_stir(); /* noop on recent arc4random() implementations */ 538 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 539 540 #ifdef WITH_OPENSSL 541 RAND_seed(rnd, sizeof(rnd)); 542 /* give libcrypto a chance to notice the PID change */ 543 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 544 fatal("%s: RAND_bytes failed", __func__); 545 #endif 546 547 explicit_bzero(rnd, sizeof(rnd)); 548 } 549 550 static void 551 privsep_preauth_child(void) 552 { 553 gid_t gidset[1]; 554 555 /* Enable challenge-response authentication for privilege separation */ 556 privsep_challenge_enable(); 557 558 #ifdef GSSAPI 559 /* Cache supported mechanism OIDs for later use */ 560 ssh_gssapi_prepare_supported_oids(); 561 #endif 562 563 reseed_prngs(); 564 565 /* Demote the private keys to public keys. */ 566 demote_sensitive_data(); 567 568 /* Demote the child */ 569 if (privsep_chroot) { 570 /* Change our root directory */ 571 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 572 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 573 strerror(errno)); 574 if (chdir("/") == -1) 575 fatal("chdir(\"/\"): %s", strerror(errno)); 576 577 /* Drop our privileges */ 578 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 579 (u_int)privsep_pw->pw_gid); 580 gidset[0] = privsep_pw->pw_gid; 581 if (setgroups(1, gidset) < 0) 582 fatal("setgroups: %.100s", strerror(errno)); 583 permanently_set_uid(privsep_pw); 584 } 585 } 586 587 static int 588 privsep_preauth(Authctxt *authctxt) 589 { 590 int status, r; 591 pid_t pid; 592 struct ssh_sandbox *box = NULL; 593 594 /* Set up unprivileged child process to deal with network data */ 595 pmonitor = monitor_init(); 596 /* Store a pointer to the kex for later rekeying */ 597 pmonitor->m_pkex = &active_state->kex; 598 599 if (use_privsep == PRIVSEP_ON) 600 box = ssh_sandbox_init(pmonitor); 601 pid = fork(); 602 if (pid == -1) { 603 fatal("fork of unprivileged child failed"); 604 } else if (pid != 0) { 605 debug2("Network child is on pid %ld", (long)pid); 606 607 pmonitor->m_pid = pid; 608 if (have_agent) { 609 r = ssh_get_authentication_socket(&auth_sock); 610 if (r != 0) { 611 error("Could not get agent socket: %s", 612 ssh_err(r)); 613 have_agent = 0; 614 } 615 } 616 if (box != NULL) 617 ssh_sandbox_parent_preauth(box, pid); 618 monitor_child_preauth(authctxt, pmonitor); 619 620 /* Wait for the child's exit status */ 621 while (waitpid(pid, &status, 0) < 0) { 622 if (errno == EINTR) 623 continue; 624 pmonitor->m_pid = -1; 625 fatal("%s: waitpid: %s", __func__, strerror(errno)); 626 } 627 privsep_is_preauth = 0; 628 pmonitor->m_pid = -1; 629 if (WIFEXITED(status)) { 630 if (WEXITSTATUS(status) != 0) 631 fatal("%s: preauth child exited with status %d", 632 __func__, WEXITSTATUS(status)); 633 } else if (WIFSIGNALED(status)) 634 fatal("%s: preauth child terminated by signal %d", 635 __func__, WTERMSIG(status)); 636 if (box != NULL) 637 ssh_sandbox_parent_finish(box); 638 return 1; 639 } else { 640 /* child */ 641 close(pmonitor->m_sendfd); 642 close(pmonitor->m_log_recvfd); 643 644 /* Arrange for logging to be sent to the monitor */ 645 set_log_handler(mm_log_handler, pmonitor); 646 647 privsep_preauth_child(); 648 setproctitle("%s", "[net]"); 649 if (box != NULL) 650 ssh_sandbox_child(box); 651 652 return 0; 653 } 654 } 655 656 static void 657 privsep_postauth(Authctxt *authctxt) 658 { 659 #ifdef DISABLE_FD_PASSING 660 if (1) { 661 #else 662 if (authctxt->pw->pw_uid == 0) { 663 #endif 664 /* File descriptor passing is broken or root login */ 665 use_privsep = 0; 666 goto skip; 667 } 668 669 /* New socket pair */ 670 monitor_reinit(pmonitor); 671 672 pmonitor->m_pid = fork(); 673 if (pmonitor->m_pid == -1) 674 fatal("fork of unprivileged child failed"); 675 else if (pmonitor->m_pid != 0) { 676 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 677 sshbuf_reset(loginmsg); 678 monitor_clear_keystate(pmonitor); 679 monitor_child_postauth(pmonitor); 680 681 /* NEVERREACHED */ 682 exit(0); 683 } 684 685 /* child */ 686 687 close(pmonitor->m_sendfd); 688 pmonitor->m_sendfd = -1; 689 690 /* Demote the private keys to public keys. */ 691 demote_sensitive_data(); 692 693 reseed_prngs(); 694 695 /* Drop privileges */ 696 do_setusercontext(authctxt->pw); 697 698 skip: 699 /* It is safe now to apply the key state */ 700 monitor_apply_keystate(pmonitor); 701 702 /* 703 * Tell the packet layer that authentication was successful, since 704 * this information is not part of the key state. 705 */ 706 packet_set_authenticated(); 707 } 708 709 static void 710 append_hostkey_type(struct sshbuf *b, const char *s) 711 { 712 int r; 713 714 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 715 debug3("%s: %s key not permitted by HostkeyAlgorithms", 716 __func__, s); 717 return; 718 } 719 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 720 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); 721 } 722 723 static char * 724 list_hostkey_types(void) 725 { 726 struct sshbuf *b; 727 struct sshkey *key; 728 char *ret; 729 u_int i; 730 731 if ((b = sshbuf_new()) == NULL) 732 fatal("%s: sshbuf_new failed", __func__); 733 for (i = 0; i < options.num_host_key_files; i++) { 734 key = sensitive_data.host_keys[i]; 735 if (key == NULL) 736 key = sensitive_data.host_pubkeys[i]; 737 if (key == NULL) 738 continue; 739 switch (key->type) { 740 case KEY_RSA: 741 /* for RSA we also support SHA2 signatures */ 742 append_hostkey_type(b, "rsa-sha2-512"); 743 append_hostkey_type(b, "rsa-sha2-256"); 744 /* FALLTHROUGH */ 745 case KEY_DSA: 746 case KEY_ECDSA: 747 case KEY_ED25519: 748 case KEY_XMSS: 749 append_hostkey_type(b, sshkey_ssh_name(key)); 750 break; 751 } 752 /* If the private key has a cert peer, then list that too */ 753 key = sensitive_data.host_certificates[i]; 754 if (key == NULL) 755 continue; 756 switch (key->type) { 757 case KEY_RSA_CERT: 758 /* for RSA we also support SHA2 signatures */ 759 append_hostkey_type(b, 760 "rsa-sha2-512-cert-v01@openssh.com"); 761 append_hostkey_type(b, 762 "rsa-sha2-256-cert-v01@openssh.com"); 763 /* FALLTHROUGH */ 764 case KEY_DSA_CERT: 765 case KEY_ECDSA_CERT: 766 case KEY_ED25519_CERT: 767 case KEY_XMSS_CERT: 768 append_hostkey_type(b, sshkey_ssh_name(key)); 769 break; 770 } 771 } 772 if ((ret = sshbuf_dup_string(b)) == NULL) 773 fatal("%s: sshbuf_dup_string failed", __func__); 774 sshbuf_free(b); 775 debug("%s: %s", __func__, ret); 776 return ret; 777 } 778 779 static struct sshkey * 780 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 781 { 782 u_int i; 783 struct sshkey *key; 784 785 for (i = 0; i < options.num_host_key_files; i++) { 786 switch (type) { 787 case KEY_RSA_CERT: 788 case KEY_DSA_CERT: 789 case KEY_ECDSA_CERT: 790 case KEY_ED25519_CERT: 791 case KEY_XMSS_CERT: 792 key = sensitive_data.host_certificates[i]; 793 break; 794 default: 795 key = sensitive_data.host_keys[i]; 796 if (key == NULL && !need_private) 797 key = sensitive_data.host_pubkeys[i]; 798 break; 799 } 800 if (key != NULL && key->type == type && 801 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 802 return need_private ? 803 sensitive_data.host_keys[i] : key; 804 } 805 return NULL; 806 } 807 808 struct sshkey * 809 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 810 { 811 return get_hostkey_by_type(type, nid, 0, ssh); 812 } 813 814 struct sshkey * 815 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 816 { 817 return get_hostkey_by_type(type, nid, 1, ssh); 818 } 819 820 struct sshkey * 821 get_hostkey_by_index(int ind) 822 { 823 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 824 return (NULL); 825 return (sensitive_data.host_keys[ind]); 826 } 827 828 struct sshkey * 829 get_hostkey_public_by_index(int ind, struct ssh *ssh) 830 { 831 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 832 return (NULL); 833 return (sensitive_data.host_pubkeys[ind]); 834 } 835 836 int 837 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 838 { 839 u_int i; 840 841 for (i = 0; i < options.num_host_key_files; i++) { 842 if (sshkey_is_cert(key)) { 843 if (key == sensitive_data.host_certificates[i] || 844 (compare && sensitive_data.host_certificates[i] && 845 sshkey_equal(key, 846 sensitive_data.host_certificates[i]))) 847 return (i); 848 } else { 849 if (key == sensitive_data.host_keys[i] || 850 (compare && sensitive_data.host_keys[i] && 851 sshkey_equal(key, sensitive_data.host_keys[i]))) 852 return (i); 853 if (key == sensitive_data.host_pubkeys[i] || 854 (compare && sensitive_data.host_pubkeys[i] && 855 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 856 return (i); 857 } 858 } 859 return (-1); 860 } 861 862 /* Inform the client of all hostkeys */ 863 static void 864 notify_hostkeys(struct ssh *ssh) 865 { 866 struct sshbuf *buf; 867 struct sshkey *key; 868 u_int i, nkeys; 869 int r; 870 char *fp; 871 872 /* Some clients cannot cope with the hostkeys message, skip those. */ 873 if (datafellows & SSH_BUG_HOSTKEYS) 874 return; 875 876 if ((buf = sshbuf_new()) == NULL) 877 fatal("%s: sshbuf_new", __func__); 878 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 879 key = get_hostkey_public_by_index(i, ssh); 880 if (key == NULL || key->type == KEY_UNSPEC || 881 sshkey_is_cert(key)) 882 continue; 883 fp = sshkey_fingerprint(key, options.fingerprint_hash, 884 SSH_FP_DEFAULT); 885 debug3("%s: key %d: %s %s", __func__, i, 886 sshkey_ssh_name(key), fp); 887 free(fp); 888 if (nkeys == 0) { 889 packet_start(SSH2_MSG_GLOBAL_REQUEST); 890 packet_put_cstring("hostkeys-00@openssh.com"); 891 packet_put_char(0); /* want-reply */ 892 } 893 sshbuf_reset(buf); 894 if ((r = sshkey_putb(key, buf)) != 0) 895 fatal("%s: couldn't put hostkey %d: %s", 896 __func__, i, ssh_err(r)); 897 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 898 nkeys++; 899 } 900 debug3("%s: sent %u hostkeys", __func__, nkeys); 901 if (nkeys == 0) 902 fatal("%s: no hostkeys", __func__); 903 packet_send(); 904 sshbuf_free(buf); 905 } 906 907 /* 908 * returns 1 if connection should be dropped, 0 otherwise. 909 * dropping starts at connection #max_startups_begin with a probability 910 * of (max_startups_rate/100). the probability increases linearly until 911 * all connections are dropped for startups > max_startups 912 */ 913 static int 914 drop_connection(int startups) 915 { 916 int p, r; 917 918 if (startups < options.max_startups_begin) 919 return 0; 920 if (startups >= options.max_startups) 921 return 1; 922 if (options.max_startups_rate == 100) 923 return 1; 924 925 p = 100 - options.max_startups_rate; 926 p *= startups - options.max_startups_begin; 927 p /= options.max_startups - options.max_startups_begin; 928 p += options.max_startups_rate; 929 r = arc4random_uniform(100); 930 931 debug("drop_connection: p %d, r %d", p, r); 932 return (r < p) ? 1 : 0; 933 } 934 935 static void 936 usage(void) 937 { 938 if (options.version_addendum && *options.version_addendum != '\0') 939 fprintf(stderr, "%s %s, %s\n", 940 SSH_RELEASE, 941 options.version_addendum, OPENSSL_VERSION_STRING); 942 else 943 fprintf(stderr, "%s, %s\n", 944 SSH_RELEASE, OPENSSL_VERSION_STRING); 945 fprintf(stderr, 946 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 947 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 948 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 949 ); 950 exit(1); 951 } 952 953 static void 954 send_rexec_state(int fd, struct sshbuf *conf) 955 { 956 struct sshbuf *m; 957 int r; 958 959 debug3("%s: entering fd = %d config len %zu", __func__, fd, 960 sshbuf_len(conf)); 961 962 /* 963 * Protocol from reexec master to child: 964 * string configuration 965 * string rngseed (only if OpenSSL is not self-seeded) 966 */ 967 if ((m = sshbuf_new()) == NULL) 968 fatal("%s: sshbuf_new failed", __func__); 969 if ((r = sshbuf_put_stringb(m, conf)) != 0) 970 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 971 972 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 973 rexec_send_rng_seed(m); 974 #endif 975 976 if (ssh_msg_send(fd, 0, m) == -1) 977 fatal("%s: ssh_msg_send failed", __func__); 978 979 sshbuf_free(m); 980 981 debug3("%s: done", __func__); 982 } 983 984 static void 985 recv_rexec_state(int fd, struct sshbuf *conf) 986 { 987 struct sshbuf *m; 988 u_char *cp, ver; 989 size_t len; 990 int r; 991 992 debug3("%s: entering fd = %d", __func__, fd); 993 994 if ((m = sshbuf_new()) == NULL) 995 fatal("%s: sshbuf_new failed", __func__); 996 if (ssh_msg_recv(fd, m) == -1) 997 fatal("%s: ssh_msg_recv failed", __func__); 998 if ((r = sshbuf_get_u8(m, &ver)) != 0) 999 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1000 if (ver != 0) 1001 fatal("%s: rexec version mismatch", __func__); 1002 if ((r = sshbuf_get_string(m, &cp, &len)) != 0) 1003 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1004 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 1005 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1006 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1007 rexec_recv_rng_seed(m); 1008 #endif 1009 1010 free(cp); 1011 sshbuf_free(m); 1012 1013 debug3("%s: done", __func__); 1014 } 1015 1016 /* Accept a connection from inetd */ 1017 static void 1018 server_accept_inetd(int *sock_in, int *sock_out) 1019 { 1020 int fd; 1021 1022 startup_pipe = -1; 1023 if (rexeced_flag) { 1024 close(REEXEC_CONFIG_PASS_FD); 1025 *sock_in = *sock_out = dup(STDIN_FILENO); 1026 if (!debug_flag) { 1027 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1028 close(REEXEC_STARTUP_PIPE_FD); 1029 } 1030 } else { 1031 *sock_in = dup(STDIN_FILENO); 1032 *sock_out = dup(STDOUT_FILENO); 1033 } 1034 /* 1035 * We intentionally do not close the descriptors 0, 1, and 2 1036 * as our code for setting the descriptors won't work if 1037 * ttyfd happens to be one of those. 1038 */ 1039 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1040 dup2(fd, STDIN_FILENO); 1041 dup2(fd, STDOUT_FILENO); 1042 if (!log_stderr) 1043 dup2(fd, STDERR_FILENO); 1044 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1045 close(fd); 1046 } 1047 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1048 } 1049 1050 /* 1051 * Listen for TCP connections 1052 */ 1053 static void 1054 listen_on_addrs(struct listenaddr *la) 1055 { 1056 int ret, listen_sock; 1057 struct addrinfo *ai; 1058 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1059 int socksize; 1060 socklen_t len; 1061 1062 for (ai = la->addrs; ai; ai = ai->ai_next) { 1063 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1064 continue; 1065 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1066 fatal("Too many listen sockets. " 1067 "Enlarge MAX_LISTEN_SOCKS"); 1068 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1069 ntop, sizeof(ntop), strport, sizeof(strport), 1070 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1071 error("getnameinfo failed: %.100s", 1072 ssh_gai_strerror(ret)); 1073 continue; 1074 } 1075 /* Create socket for listening. */ 1076 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1077 ai->ai_protocol); 1078 if (listen_sock < 0) { 1079 /* kernel may not support ipv6 */ 1080 verbose("socket: %.100s", strerror(errno)); 1081 continue; 1082 } 1083 if (set_nonblock(listen_sock) == -1) { 1084 close(listen_sock); 1085 continue; 1086 } 1087 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1088 verbose("socket: CLOEXEC: %s", strerror(errno)); 1089 close(listen_sock); 1090 continue; 1091 } 1092 /* Socket options */ 1093 set_reuseaddr(listen_sock); 1094 if (la->rdomain != NULL && 1095 set_rdomain(listen_sock, la->rdomain) == -1) { 1096 close(listen_sock); 1097 continue; 1098 } 1099 1100 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1101 if (ai->ai_family == AF_INET6) 1102 sock_set_v6only(listen_sock); 1103 1104 debug("Bind to port %s on %s.", strport, ntop); 1105 1106 len = sizeof(socksize); 1107 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1108 debug("Server TCP RWIN socket size: %d", socksize); 1109 1110 /* Bind the socket to the desired port. */ 1111 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1112 error("Bind to port %s on %s failed: %.200s.", 1113 strport, ntop, strerror(errno)); 1114 close(listen_sock); 1115 continue; 1116 } 1117 listen_socks[num_listen_socks] = listen_sock; 1118 num_listen_socks++; 1119 1120 /* Start listening on the port. */ 1121 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1122 fatal("listen on [%s]:%s: %.100s", 1123 ntop, strport, strerror(errno)); 1124 logit("Server listening on %s port %s%s%s.", 1125 ntop, strport, 1126 la->rdomain == NULL ? "" : " rdomain ", 1127 la->rdomain == NULL ? "" : la->rdomain); 1128 } 1129 } 1130 1131 static void 1132 server_listen(void) 1133 { 1134 u_int i; 1135 1136 for (i = 0; i < options.num_listen_addrs; i++) { 1137 listen_on_addrs(&options.listen_addrs[i]); 1138 freeaddrinfo(options.listen_addrs[i].addrs); 1139 free(options.listen_addrs[i].rdomain); 1140 memset(&options.listen_addrs[i], 0, 1141 sizeof(options.listen_addrs[i])); 1142 } 1143 free(options.listen_addrs); 1144 options.listen_addrs = NULL; 1145 options.num_listen_addrs = 0; 1146 1147 if (!num_listen_socks) 1148 fatal("Cannot bind any address."); 1149 } 1150 1151 /* 1152 * The main TCP accept loop. Note that, for the non-debug case, returns 1153 * from this function are in a forked subprocess. 1154 */ 1155 static void 1156 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1157 { 1158 fd_set *fdset; 1159 int i, j, ret, maxfd; 1160 int startups = 0; 1161 int startup_p[2] = { -1 , -1 }; 1162 struct sockaddr_storage from; 1163 socklen_t fromlen; 1164 pid_t pid; 1165 u_char rnd[256]; 1166 1167 /* setup fd set for accept */ 1168 fdset = NULL; 1169 maxfd = 0; 1170 for (i = 0; i < num_listen_socks; i++) 1171 if (listen_socks[i] > maxfd) 1172 maxfd = listen_socks[i]; 1173 /* pipes connected to unauthenticated childs */ 1174 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1175 for (i = 0; i < options.max_startups; i++) 1176 startup_pipes[i] = -1; 1177 1178 /* 1179 * Stay listening for connections until the system crashes or 1180 * the daemon is killed with a signal. 1181 */ 1182 for (;;) { 1183 if (received_sighup) 1184 sighup_restart(); 1185 free(fdset); 1186 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1187 sizeof(fd_mask)); 1188 1189 for (i = 0; i < num_listen_socks; i++) 1190 FD_SET(listen_socks[i], fdset); 1191 for (i = 0; i < options.max_startups; i++) 1192 if (startup_pipes[i] != -1) 1193 FD_SET(startup_pipes[i], fdset); 1194 1195 /* Wait in select until there is a connection. */ 1196 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1197 if (ret < 0 && errno != EINTR) 1198 error("select: %.100s", strerror(errno)); 1199 if (received_sigterm) { 1200 logit("Received signal %d; terminating.", 1201 (int) received_sigterm); 1202 close_listen_socks(); 1203 if (options.pid_file != NULL) 1204 unlink(options.pid_file); 1205 exit(received_sigterm == SIGTERM ? 0 : 255); 1206 } 1207 if (ret < 0) 1208 continue; 1209 1210 for (i = 0; i < options.max_startups; i++) 1211 if (startup_pipes[i] != -1 && 1212 FD_ISSET(startup_pipes[i], fdset)) { 1213 /* 1214 * the read end of the pipe is ready 1215 * if the child has closed the pipe 1216 * after successful authentication 1217 * or if the child has died 1218 */ 1219 close(startup_pipes[i]); 1220 startup_pipes[i] = -1; 1221 startups--; 1222 } 1223 for (i = 0; i < num_listen_socks; i++) { 1224 if (!FD_ISSET(listen_socks[i], fdset)) 1225 continue; 1226 fromlen = sizeof(from); 1227 *newsock = accept(listen_socks[i], 1228 (struct sockaddr *)&from, &fromlen); 1229 if (*newsock < 0) { 1230 if (errno != EINTR && errno != EWOULDBLOCK && 1231 errno != ECONNABORTED && errno != EAGAIN) 1232 error("accept: %.100s", 1233 strerror(errno)); 1234 if (errno == EMFILE || errno == ENFILE) 1235 usleep(100 * 1000); 1236 continue; 1237 } 1238 if (unset_nonblock(*newsock) == -1) { 1239 close(*newsock); 1240 continue; 1241 } 1242 if (drop_connection(startups) == 1) { 1243 char *laddr = get_local_ipaddr(*newsock); 1244 char *raddr = get_peer_ipaddr(*newsock); 1245 1246 verbose("drop connection #%d from [%s]:%d " 1247 "on [%s]:%d past MaxStartups", startups, 1248 raddr, get_peer_port(*newsock), 1249 laddr, get_local_port(*newsock)); 1250 free(laddr); 1251 free(raddr); 1252 close(*newsock); 1253 continue; 1254 } 1255 if (pipe(startup_p) == -1) { 1256 close(*newsock); 1257 continue; 1258 } 1259 1260 if (rexec_flag && socketpair(AF_UNIX, 1261 SOCK_STREAM, 0, config_s) == -1) { 1262 error("reexec socketpair: %s", 1263 strerror(errno)); 1264 close(*newsock); 1265 close(startup_p[0]); 1266 close(startup_p[1]); 1267 continue; 1268 } 1269 1270 for (j = 0; j < options.max_startups; j++) 1271 if (startup_pipes[j] == -1) { 1272 startup_pipes[j] = startup_p[0]; 1273 if (maxfd < startup_p[0]) 1274 maxfd = startup_p[0]; 1275 startups++; 1276 break; 1277 } 1278 1279 /* 1280 * Got connection. Fork a child to handle it, unless 1281 * we are in debugging mode. 1282 */ 1283 if (debug_flag) { 1284 /* 1285 * In debugging mode. Close the listening 1286 * socket, and start processing the 1287 * connection without forking. 1288 */ 1289 debug("Server will not fork when running in debugging mode."); 1290 close_listen_socks(); 1291 *sock_in = *newsock; 1292 *sock_out = *newsock; 1293 close(startup_p[0]); 1294 close(startup_p[1]); 1295 startup_pipe = -1; 1296 pid = getpid(); 1297 if (rexec_flag) { 1298 send_rexec_state(config_s[0], cfg); 1299 close(config_s[0]); 1300 } 1301 break; 1302 } 1303 1304 /* 1305 * Normal production daemon. Fork, and have 1306 * the child process the connection. The 1307 * parent continues listening. 1308 */ 1309 platform_pre_fork(); 1310 if ((pid = fork()) == 0) { 1311 /* 1312 * Child. Close the listening and 1313 * max_startup sockets. Start using 1314 * the accepted socket. Reinitialize 1315 * logging (since our pid has changed). 1316 * We break out of the loop to handle 1317 * the connection. 1318 */ 1319 platform_post_fork_child(); 1320 startup_pipe = startup_p[1]; 1321 close_startup_pipes(); 1322 close_listen_socks(); 1323 *sock_in = *newsock; 1324 *sock_out = *newsock; 1325 log_init(__progname, 1326 options.log_level, 1327 options.log_facility, 1328 log_stderr); 1329 if (rexec_flag) 1330 close(config_s[0]); 1331 break; 1332 } 1333 1334 /* Parent. Stay in the loop. */ 1335 platform_post_fork_parent(pid); 1336 if (pid < 0) 1337 error("fork: %.100s", strerror(errno)); 1338 else 1339 debug("Forked child %ld.", (long)pid); 1340 1341 close(startup_p[1]); 1342 1343 if (rexec_flag) { 1344 send_rexec_state(config_s[0], cfg); 1345 close(config_s[0]); 1346 close(config_s[1]); 1347 } 1348 close(*newsock); 1349 1350 /* 1351 * Ensure that our random state differs 1352 * from that of the child 1353 */ 1354 arc4random_stir(); 1355 arc4random_buf(rnd, sizeof(rnd)); 1356 #ifdef WITH_OPENSSL 1357 RAND_seed(rnd, sizeof(rnd)); 1358 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1359 fatal("%s: RAND_bytes failed", __func__); 1360 #endif 1361 explicit_bzero(rnd, sizeof(rnd)); 1362 } 1363 1364 /* child process check (or debug mode) */ 1365 if (num_listen_socks < 0) 1366 break; 1367 } 1368 } 1369 1370 /* 1371 * If IP options are supported, make sure there are none (log and 1372 * return an error if any are found). Basically we are worried about 1373 * source routing; it can be used to pretend you are somebody 1374 * (ip-address) you are not. That itself may be "almost acceptable" 1375 * under certain circumstances, but rhosts authentication is useless 1376 * if source routing is accepted. Notice also that if we just dropped 1377 * source routing here, the other side could use IP spoofing to do 1378 * rest of the interaction and could still bypass security. So we 1379 * exit here if we detect any IP options. 1380 */ 1381 static void 1382 check_ip_options(struct ssh *ssh) 1383 { 1384 #ifdef IP_OPTIONS 1385 int sock_in = ssh_packet_get_connection_in(ssh); 1386 struct sockaddr_storage from; 1387 u_char opts[200]; 1388 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1389 char text[sizeof(opts) * 3 + 1]; 1390 1391 memset(&from, 0, sizeof(from)); 1392 if (getpeername(sock_in, (struct sockaddr *)&from, 1393 &fromlen) < 0) 1394 return; 1395 if (from.ss_family != AF_INET) 1396 return; 1397 /* XXX IPv6 options? */ 1398 1399 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1400 &option_size) >= 0 && option_size != 0) { 1401 text[0] = '\0'; 1402 for (i = 0; i < option_size; i++) 1403 snprintf(text + i*3, sizeof(text) - i*3, 1404 " %2.2x", opts[i]); 1405 fatal("Connection from %.100s port %d with IP opts: %.800s", 1406 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1407 } 1408 return; 1409 #endif /* IP_OPTIONS */ 1410 } 1411 1412 /* Set the routing domain for this process */ 1413 static void 1414 set_process_rdomain(struct ssh *ssh, const char *name) 1415 { 1416 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) 1417 if (name == NULL) 1418 return; /* default */ 1419 1420 if (strcmp(name, "%D") == 0) { 1421 /* "expands" to routing domain of connection */ 1422 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1423 return; 1424 } 1425 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ 1426 return sys_set_process_rdomain(name); 1427 #elif defined(__OpenBSD__) 1428 int rtable, ortable = getrtable(); 1429 const char *errstr; 1430 1431 if (name == NULL) 1432 return; /* default */ 1433 1434 if (strcmp(name, "%D") == 0) { 1435 /* "expands" to routing domain of connection */ 1436 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1437 return; 1438 } 1439 1440 rtable = (int)strtonum(name, 0, 255, &errstr); 1441 if (errstr != NULL) /* Shouldn't happen */ 1442 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1443 if (rtable != ortable && setrtable(rtable) != 0) 1444 fatal("Unable to set routing domain %d: %s", 1445 rtable, strerror(errno)); 1446 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1447 #else /* defined(__OpenBSD__) */ 1448 fatal("Unable to set routing domain: not supported in this platform"); 1449 #endif 1450 } 1451 1452 static void 1453 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1454 const struct sshkey *key) 1455 { 1456 static struct ssh_digest_ctx *ctx; 1457 u_char *hash; 1458 size_t len; 1459 struct sshbuf *buf; 1460 int r; 1461 1462 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1463 fatal("%s: ssh_digest_start", __func__); 1464 if (key == NULL) { /* finalize */ 1465 /* add server config in case we are using agent for host keys */ 1466 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1467 sshbuf_len(server_cfg)) != 0) 1468 fatal("%s: ssh_digest_update", __func__); 1469 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1470 hash = xmalloc(len); 1471 if (ssh_digest_final(ctx, hash, len) != 0) 1472 fatal("%s: ssh_digest_final", __func__); 1473 options.timing_secret = PEEK_U64(hash); 1474 freezero(hash, len); 1475 ssh_digest_free(ctx); 1476 ctx = NULL; 1477 return; 1478 } 1479 if ((buf = sshbuf_new()) == NULL) 1480 fatal("%s could not allocate buffer", __func__); 1481 if ((r = sshkey_private_serialize(key, buf)) != 0) 1482 fatal("sshkey_private_serialize: %s", ssh_err(r)); 1483 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1484 fatal("%s: ssh_digest_update", __func__); 1485 sshbuf_reset(buf); 1486 sshbuf_free(buf); 1487 } 1488 1489 /* 1490 * Main program for the daemon. 1491 */ 1492 int 1493 main(int ac, char **av) 1494 { 1495 struct ssh *ssh = NULL; 1496 extern char *optarg; 1497 extern int optind; 1498 int r, opt, on = 1, already_daemon, remote_port; 1499 int sock_in = -1, sock_out = -1, newsock = -1; 1500 const char *remote_ip, *rdomain; 1501 char *fp, *line, *laddr, *logfile = NULL; 1502 int config_s[2] = { -1 , -1 }; 1503 u_int i, j; 1504 u_int64_t ibytes, obytes; 1505 mode_t new_umask; 1506 struct sshkey *key; 1507 struct sshkey *pubkey; 1508 int keytype; 1509 Authctxt *authctxt; 1510 struct connection_info *connection_info = NULL; 1511 1512 ssh_malloc_init(); /* must be called before any mallocs */ 1513 1514 #ifdef HAVE_SECUREWARE 1515 (void)set_auth_parameters(ac, av); 1516 #endif 1517 __progname = ssh_get_progname(av[0]); 1518 1519 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1520 saved_argc = ac; 1521 rexec_argc = ac; 1522 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1523 for (i = 0; (int)i < ac; i++) 1524 saved_argv[i] = xstrdup(av[i]); 1525 saved_argv[i] = NULL; 1526 1527 #ifndef HAVE_SETPROCTITLE 1528 /* Prepare for later setproctitle emulation */ 1529 compat_init_setproctitle(ac, av); 1530 av = saved_argv; 1531 #endif 1532 1533 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1534 debug("setgroups(): %.200s", strerror(errno)); 1535 1536 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1537 sanitise_stdfd(); 1538 1539 /* Initialize configuration options to their default values. */ 1540 initialize_server_options(&options); 1541 1542 /* Parse command-line arguments. */ 1543 while ((opt = getopt(ac, av, 1544 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1545 switch (opt) { 1546 case '4': 1547 options.address_family = AF_INET; 1548 break; 1549 case '6': 1550 options.address_family = AF_INET6; 1551 break; 1552 case 'f': 1553 config_file_name = optarg; 1554 break; 1555 case 'c': 1556 servconf_add_hostcert("[command-line]", 0, 1557 &options, optarg); 1558 break; 1559 case 'd': 1560 if (debug_flag == 0) { 1561 debug_flag = 1; 1562 options.log_level = SYSLOG_LEVEL_DEBUG1; 1563 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1564 options.log_level++; 1565 break; 1566 case 'D': 1567 no_daemon_flag = 1; 1568 break; 1569 case 'E': 1570 logfile = optarg; 1571 /* FALLTHROUGH */ 1572 case 'e': 1573 log_stderr = 1; 1574 break; 1575 case 'i': 1576 inetd_flag = 1; 1577 break; 1578 case 'r': 1579 rexec_flag = 0; 1580 break; 1581 case 'R': 1582 rexeced_flag = 1; 1583 inetd_flag = 1; 1584 break; 1585 case 'Q': 1586 /* ignored */ 1587 break; 1588 case 'q': 1589 options.log_level = SYSLOG_LEVEL_QUIET; 1590 break; 1591 case 'b': 1592 /* protocol 1, ignored */ 1593 break; 1594 case 'p': 1595 options.ports_from_cmdline = 1; 1596 if (options.num_ports >= MAX_PORTS) { 1597 fprintf(stderr, "too many ports.\n"); 1598 exit(1); 1599 } 1600 options.ports[options.num_ports++] = a2port(optarg); 1601 if (options.ports[options.num_ports-1] <= 0) { 1602 fprintf(stderr, "Bad port number.\n"); 1603 exit(1); 1604 } 1605 break; 1606 case 'g': 1607 if ((options.login_grace_time = convtime(optarg)) == -1) { 1608 fprintf(stderr, "Invalid login grace time.\n"); 1609 exit(1); 1610 } 1611 break; 1612 case 'k': 1613 /* protocol 1, ignored */ 1614 break; 1615 case 'h': 1616 servconf_add_hostkey("[command-line]", 0, 1617 &options, optarg); 1618 break; 1619 case 't': 1620 test_flag = 1; 1621 break; 1622 case 'T': 1623 test_flag = 2; 1624 break; 1625 case 'C': 1626 connection_info = get_connection_info(0, 0); 1627 if (parse_server_match_testspec(connection_info, 1628 optarg) == -1) 1629 exit(1); 1630 break; 1631 case 'u': 1632 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1633 if (utmp_len > HOST_NAME_MAX+1) { 1634 fprintf(stderr, "Invalid utmp length.\n"); 1635 exit(1); 1636 } 1637 break; 1638 case 'o': 1639 line = xstrdup(optarg); 1640 if (process_server_config_line(&options, line, 1641 "command-line", 0, NULL, NULL) != 0) 1642 exit(1); 1643 free(line); 1644 break; 1645 case '?': 1646 default: 1647 usage(); 1648 break; 1649 } 1650 } 1651 if (rexeced_flag || inetd_flag) 1652 rexec_flag = 0; 1653 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1654 fatal("sshd re-exec requires execution with an absolute path"); 1655 if (rexeced_flag) 1656 closefrom(REEXEC_MIN_FREE_FD); 1657 else 1658 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1659 1660 #ifdef WITH_OPENSSL 1661 OpenSSL_add_all_algorithms(); 1662 #endif 1663 1664 /* If requested, redirect the logs to the specified logfile. */ 1665 if (logfile != NULL) 1666 log_redirect_stderr_to(logfile); 1667 /* 1668 * Force logging to stderr until we have loaded the private host 1669 * key (unless started from inetd) 1670 */ 1671 log_init(__progname, 1672 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1673 SYSLOG_LEVEL_INFO : options.log_level, 1674 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1675 SYSLOG_FACILITY_AUTH : options.log_facility, 1676 log_stderr || !inetd_flag); 1677 1678 /* 1679 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1680 * root's environment 1681 */ 1682 if (getenv("KRB5CCNAME") != NULL) 1683 (void) unsetenv("KRB5CCNAME"); 1684 1685 sensitive_data.have_ssh2_key = 0; 1686 1687 /* 1688 * If we're not doing an extended test do not silently ignore connection 1689 * test params. 1690 */ 1691 if (test_flag < 2 && connection_info != NULL) 1692 fatal("Config test connection parameter (-C) provided without " 1693 "test mode (-T)"); 1694 1695 /* Fetch our configuration */ 1696 if ((cfg = sshbuf_new()) == NULL) 1697 fatal("%s: sshbuf_new failed", __func__); 1698 if (rexeced_flag) 1699 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1700 else if (strcasecmp(config_file_name, "none") != 0) 1701 load_server_config(config_file_name, cfg); 1702 1703 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1704 cfg, NULL); 1705 1706 seed_rng(); 1707 1708 /* Fill in default values for those options not explicitly set. */ 1709 fill_default_server_options(&options); 1710 1711 /* challenge-response is implemented via keyboard interactive */ 1712 if (options.challenge_response_authentication) 1713 options.kbd_interactive_authentication = 1; 1714 1715 /* Check that options are sensible */ 1716 if (options.authorized_keys_command_user == NULL && 1717 (options.authorized_keys_command != NULL && 1718 strcasecmp(options.authorized_keys_command, "none") != 0)) 1719 fatal("AuthorizedKeysCommand set without " 1720 "AuthorizedKeysCommandUser"); 1721 if (options.authorized_principals_command_user == NULL && 1722 (options.authorized_principals_command != NULL && 1723 strcasecmp(options.authorized_principals_command, "none") != 0)) 1724 fatal("AuthorizedPrincipalsCommand set without " 1725 "AuthorizedPrincipalsCommandUser"); 1726 1727 /* 1728 * Check whether there is any path through configured auth methods. 1729 * Unfortunately it is not possible to verify this generally before 1730 * daemonisation in the presence of Match block, but this catches 1731 * and warns for trivial misconfigurations that could break login. 1732 */ 1733 if (options.num_auth_methods != 0) { 1734 for (i = 0; i < options.num_auth_methods; i++) { 1735 if (auth2_methods_valid(options.auth_methods[i], 1736 1) == 0) 1737 break; 1738 } 1739 if (i >= options.num_auth_methods) 1740 fatal("AuthenticationMethods cannot be satisfied by " 1741 "enabled authentication methods"); 1742 } 1743 1744 /* Check that there are no remaining arguments. */ 1745 if (optind < ac) { 1746 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1747 exit(1); 1748 } 1749 1750 debug("sshd version %s, %s", SSH_VERSION, 1751 #ifdef WITH_OPENSSL 1752 SSLeay_version(SSLEAY_VERSION) 1753 #else 1754 "without OpenSSL" 1755 #endif 1756 ); 1757 1758 /* Store privilege separation user for later use if required. */ 1759 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); 1760 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1761 if (privsep_chroot || options.kerberos_authentication) 1762 fatal("Privilege separation user %s does not exist", 1763 SSH_PRIVSEP_USER); 1764 } else { 1765 privsep_pw = pwcopy(privsep_pw); 1766 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); 1767 privsep_pw->pw_passwd = xstrdup("*"); 1768 } 1769 endpwent(); 1770 1771 /* load host keys */ 1772 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1773 sizeof(struct sshkey *)); 1774 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1775 sizeof(struct sshkey *)); 1776 1777 if (options.host_key_agent) { 1778 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1779 setenv(SSH_AUTHSOCKET_ENV_NAME, 1780 options.host_key_agent, 1); 1781 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1782 have_agent = 1; 1783 else 1784 error("Could not connect to agent \"%s\": %s", 1785 options.host_key_agent, ssh_err(r)); 1786 } 1787 1788 for (i = 0; i < options.num_host_key_files; i++) { 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 error("Error loading host key \"%s\": %s", 1794 options.host_key_files[i], ssh_err(r)); 1795 if ((r = sshkey_load_public(options.host_key_files[i], 1796 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1797 error("Error loading host key \"%s\": %s", 1798 options.host_key_files[i], ssh_err(r)); 1799 if (pubkey == NULL && key != NULL) 1800 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1801 fatal("Could not demote key: \"%s\": %s", 1802 options.host_key_files[i], ssh_err(r)); 1803 sensitive_data.host_keys[i] = key; 1804 sensitive_data.host_pubkeys[i] = pubkey; 1805 1806 if (key == NULL && pubkey != NULL && have_agent) { 1807 debug("will rely on agent for hostkey %s", 1808 options.host_key_files[i]); 1809 keytype = pubkey->type; 1810 } else if (key != NULL) { 1811 keytype = key->type; 1812 accumulate_host_timing_secret(cfg, key); 1813 } else { 1814 error("Could not load host key: %s", 1815 options.host_key_files[i]); 1816 sensitive_data.host_keys[i] = NULL; 1817 sensitive_data.host_pubkeys[i] = NULL; 1818 continue; 1819 } 1820 1821 switch (keytype) { 1822 case KEY_RSA: 1823 case KEY_DSA: 1824 case KEY_ECDSA: 1825 case KEY_ED25519: 1826 case KEY_XMSS: 1827 if (have_agent || key != NULL) 1828 sensitive_data.have_ssh2_key = 1; 1829 break; 1830 } 1831 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1832 SSH_FP_DEFAULT)) == NULL) 1833 fatal("sshkey_fingerprint failed"); 1834 debug("%s host key #%d: %s %s", 1835 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1836 free(fp); 1837 } 1838 accumulate_host_timing_secret(cfg, NULL); 1839 if (!sensitive_data.have_ssh2_key) { 1840 logit("sshd: no hostkeys available -- exiting."); 1841 exit(1); 1842 } 1843 1844 /* 1845 * Load certificates. They are stored in an array at identical 1846 * indices to the public keys that they relate to. 1847 */ 1848 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1849 sizeof(struct sshkey *)); 1850 for (i = 0; i < options.num_host_key_files; i++) 1851 sensitive_data.host_certificates[i] = NULL; 1852 1853 for (i = 0; i < options.num_host_cert_files; i++) { 1854 if (options.host_cert_files[i] == NULL) 1855 continue; 1856 if ((r = sshkey_load_public(options.host_cert_files[i], 1857 &key, NULL)) != 0) { 1858 error("Could not load host certificate \"%s\": %s", 1859 options.host_cert_files[i], ssh_err(r)); 1860 continue; 1861 } 1862 if (!sshkey_is_cert(key)) { 1863 error("Certificate file is not a certificate: %s", 1864 options.host_cert_files[i]); 1865 sshkey_free(key); 1866 continue; 1867 } 1868 /* Find matching private key */ 1869 for (j = 0; j < options.num_host_key_files; j++) { 1870 if (sshkey_equal_public(key, 1871 sensitive_data.host_keys[j])) { 1872 sensitive_data.host_certificates[j] = key; 1873 break; 1874 } 1875 } 1876 if (j >= options.num_host_key_files) { 1877 error("No matching private key for certificate: %s", 1878 options.host_cert_files[i]); 1879 sshkey_free(key); 1880 continue; 1881 } 1882 sensitive_data.host_certificates[j] = key; 1883 debug("host certificate: #%u type %d %s", j, key->type, 1884 sshkey_type(key)); 1885 } 1886 1887 if (privsep_chroot) { 1888 struct stat st; 1889 1890 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1891 (S_ISDIR(st.st_mode) == 0)) 1892 fatal("Missing privilege separation directory: %s", 1893 _PATH_PRIVSEP_CHROOT_DIR); 1894 1895 #ifdef HAVE_CYGWIN 1896 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1897 (st.st_uid != getuid () || 1898 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1899 #else 1900 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1901 #endif 1902 fatal("%s must be owned by root and not group or " 1903 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1904 } 1905 1906 if (test_flag > 1) { 1907 /* 1908 * If no connection info was provided by -C then use 1909 * use a blank one that will cause no predicate to match. 1910 */ 1911 if (connection_info == NULL) 1912 connection_info = get_connection_info(0, 0); 1913 parse_server_match_config(&options, connection_info); 1914 dump_config(&options); 1915 } 1916 1917 /* Configuration looks good, so exit if in test mode. */ 1918 if (test_flag) 1919 exit(0); 1920 1921 /* 1922 * Clear out any supplemental groups we may have inherited. This 1923 * prevents inadvertent creation of files with bad modes (in the 1924 * portable version at least, it's certainly possible for PAM 1925 * to create a file, and we can't control the code in every 1926 * module which might be used). 1927 */ 1928 if (setgroups(0, NULL) < 0) 1929 debug("setgroups() failed: %.200s", strerror(errno)); 1930 1931 if (rexec_flag) { 1932 if (rexec_argc < 0) 1933 fatal("rexec_argc %d < 0", rexec_argc); 1934 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1935 for (i = 0; i < (u_int)rexec_argc; i++) { 1936 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1937 rexec_argv[i] = saved_argv[i]; 1938 } 1939 rexec_argv[rexec_argc] = "-R"; 1940 rexec_argv[rexec_argc + 1] = NULL; 1941 } 1942 1943 /* Ensure that umask disallows at least group and world write */ 1944 new_umask = umask(0077) | 0022; 1945 (void) umask(new_umask); 1946 1947 /* Initialize the log (it is reinitialized below in case we forked). */ 1948 if (debug_flag && (!inetd_flag || rexeced_flag)) 1949 log_stderr = 1; 1950 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1951 1952 /* 1953 * If not in debugging mode, not started from inetd and not already 1954 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1955 * terminal, and fork. The original process exits. 1956 */ 1957 already_daemon = daemonized(); 1958 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1959 1960 if (daemon(0, 0) < 0) 1961 fatal("daemon() failed: %.200s", strerror(errno)); 1962 1963 disconnect_controlling_tty(); 1964 } 1965 /* Reinitialize the log (because of the fork above). */ 1966 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1967 1968 /* Avoid killing the process in high-pressure swapping environments. */ 1969 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1970 debug("madvise(): %.200s", strerror(errno)); 1971 1972 /* Chdir to the root directory so that the current disk can be 1973 unmounted if desired. */ 1974 if (chdir("/") == -1) 1975 error("chdir(\"/\"): %s", strerror(errno)); 1976 1977 /* ignore SIGPIPE */ 1978 signal(SIGPIPE, SIG_IGN); 1979 1980 /* Get a connection, either from inetd or a listening TCP socket */ 1981 if (inetd_flag) { 1982 server_accept_inetd(&sock_in, &sock_out); 1983 } else { 1984 platform_pre_listen(); 1985 server_listen(); 1986 1987 signal(SIGHUP, sighup_handler); 1988 signal(SIGCHLD, main_sigchld_handler); 1989 signal(SIGTERM, sigterm_handler); 1990 signal(SIGQUIT, sigterm_handler); 1991 1992 /* 1993 * Write out the pid file after the sigterm handler 1994 * is setup and the listen sockets are bound 1995 */ 1996 if (options.pid_file != NULL && !debug_flag) { 1997 FILE *f = fopen(options.pid_file, "w"); 1998 1999 if (f == NULL) { 2000 error("Couldn't create pid file \"%s\": %s", 2001 options.pid_file, strerror(errno)); 2002 } else { 2003 fprintf(f, "%ld\n", (long) getpid()); 2004 fclose(f); 2005 } 2006 } 2007 2008 /* Accept a connection and return in a forked child */ 2009 server_accept_loop(&sock_in, &sock_out, 2010 &newsock, config_s); 2011 } 2012 2013 /* This is the child processing a new connection. */ 2014 setproctitle("%s", "[accepted]"); 2015 2016 /* 2017 * Create a new session and process group since the 4.4BSD 2018 * setlogin() affects the entire process group. We don't 2019 * want the child to be able to affect the parent. 2020 */ 2021 #if !defined(SSHD_ACQUIRES_CTTY) 2022 /* 2023 * If setsid is called, on some platforms sshd will later acquire a 2024 * controlling terminal which will result in "could not set 2025 * controlling tty" errors. 2026 */ 2027 if (!debug_flag && !inetd_flag && setsid() < 0) 2028 error("setsid: %.100s", strerror(errno)); 2029 #endif 2030 2031 if (rexec_flag) { 2032 int fd; 2033 2034 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2035 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2036 dup2(newsock, STDIN_FILENO); 2037 dup2(STDIN_FILENO, STDOUT_FILENO); 2038 if (startup_pipe == -1) 2039 close(REEXEC_STARTUP_PIPE_FD); 2040 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2041 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2042 close(startup_pipe); 2043 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2044 } 2045 2046 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2047 close(config_s[1]); 2048 2049 execv(rexec_argv[0], rexec_argv); 2050 2051 /* Reexec has failed, fall back and continue */ 2052 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2053 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2054 log_init(__progname, options.log_level, 2055 options.log_facility, log_stderr); 2056 2057 /* Clean up fds */ 2058 close(REEXEC_CONFIG_PASS_FD); 2059 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2060 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2061 dup2(fd, STDIN_FILENO); 2062 dup2(fd, STDOUT_FILENO); 2063 if (fd > STDERR_FILENO) 2064 close(fd); 2065 } 2066 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2067 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2068 } 2069 2070 /* Executed child processes don't need these. */ 2071 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2072 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2073 2074 /* 2075 * Disable the key regeneration alarm. We will not regenerate the 2076 * key since we are no longer in a position to give it to anyone. We 2077 * will not restart on SIGHUP since it no longer makes sense. 2078 */ 2079 alarm(0); 2080 signal(SIGALRM, SIG_DFL); 2081 signal(SIGHUP, SIG_DFL); 2082 signal(SIGTERM, SIG_DFL); 2083 signal(SIGQUIT, SIG_DFL); 2084 signal(SIGCHLD, SIG_DFL); 2085 signal(SIGINT, SIG_DFL); 2086 2087 #ifdef __FreeBSD__ 2088 /* 2089 * Initialize the resolver. This may not happen automatically 2090 * before privsep chroot(). 2091 */ 2092 if ((_res.options & RES_INIT) == 0) { 2093 debug("res_init()"); 2094 res_init(); 2095 } 2096 #ifdef GSSAPI 2097 /* 2098 * Force GSS-API to parse its configuration and load any 2099 * mechanism plugins. 2100 */ 2101 { 2102 gss_OID_set mechs; 2103 OM_uint32 minor_status; 2104 gss_indicate_mechs(&minor_status, &mechs); 2105 gss_release_oid_set(&minor_status, &mechs); 2106 } 2107 #endif 2108 #endif 2109 2110 /* 2111 * Register our connection. This turns encryption off because we do 2112 * not have a key. 2113 */ 2114 packet_set_connection(sock_in, sock_out); 2115 packet_set_server(); 2116 ssh = active_state; /* XXX */ 2117 2118 check_ip_options(ssh); 2119 2120 /* Prepare the channels layer */ 2121 channel_init_channels(ssh); 2122 channel_set_af(ssh, options.address_family); 2123 process_permitopen(ssh, &options); 2124 2125 /* Set SO_KEEPALIVE if requested. */ 2126 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2127 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2128 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2129 2130 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2131 debug("ssh_remote_port failed"); 2132 cleanup_exit(255); 2133 } 2134 2135 if (options.routing_domain != NULL) 2136 set_process_rdomain(ssh, options.routing_domain); 2137 2138 /* 2139 * The rest of the code depends on the fact that 2140 * ssh_remote_ipaddr() caches the remote ip, even if 2141 * the socket goes away. 2142 */ 2143 remote_ip = ssh_remote_ipaddr(ssh); 2144 2145 #ifdef HAVE_LOGIN_CAP 2146 /* Also caches remote hostname for sandboxed child. */ 2147 auth_get_canonical_hostname(ssh, options.use_dns); 2148 #endif 2149 2150 #ifdef SSH_AUDIT_EVENTS 2151 audit_connection_from(remote_ip, remote_port); 2152 #endif 2153 #ifdef LIBWRAP 2154 allow_severity = options.log_facility|LOG_INFO; 2155 deny_severity = options.log_facility|LOG_WARNING; 2156 /* Check whether logins are denied from this host. */ 2157 if (packet_connection_is_on_socket()) { 2158 struct request_info req; 2159 2160 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2161 fromhost(&req); 2162 2163 if (!hosts_access(&req)) { 2164 debug("Connection refused by tcp wrapper"); 2165 refuse(&req); 2166 /* NOTREACHED */ 2167 fatal("libwrap refuse returns"); 2168 } 2169 } 2170 #endif /* LIBWRAP */ 2171 2172 rdomain = ssh_packet_rdomain_in(ssh); 2173 2174 /* Log the connection. */ 2175 laddr = get_local_ipaddr(sock_in); 2176 verbose("Connection from %s port %d on %s port %d%s%s%s", 2177 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2178 rdomain == NULL ? "" : " rdomain \"", 2179 rdomain == NULL ? "" : rdomain, 2180 rdomain == NULL ? "" : "\""); 2181 free(laddr); 2182 2183 /* 2184 * We don't want to listen forever unless the other side 2185 * successfully authenticates itself. So we set up an alarm which is 2186 * cleared after successful authentication. A limit of zero 2187 * indicates no limit. Note that we don't set the alarm in debugging 2188 * mode; it is just annoying to have the server exit just when you 2189 * are about to discover the bug. 2190 */ 2191 signal(SIGALRM, grace_alarm_handler); 2192 if (!debug_flag) 2193 alarm(options.login_grace_time); 2194 2195 sshd_exchange_identification(ssh, sock_in, sock_out); 2196 packet_set_nonblocking(); 2197 2198 /* allocate authentication context */ 2199 authctxt = xcalloc(1, sizeof(*authctxt)); 2200 2201 authctxt->loginmsg = loginmsg; 2202 2203 /* XXX global for cleanup, access from other modules */ 2204 the_authctxt = authctxt; 2205 2206 /* Set default key authentication options */ 2207 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2208 fatal("allocation failed"); 2209 2210 /* prepare buffer to collect messages to display to user after login */ 2211 if ((loginmsg = sshbuf_new()) == NULL) 2212 fatal("%s: sshbuf_new failed", __func__); 2213 auth_debug_reset(); 2214 2215 BLACKLIST_INIT(); 2216 2217 if (use_privsep) { 2218 if (privsep_preauth(authctxt) == 1) 2219 goto authenticated; 2220 } else if (have_agent) { 2221 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2222 error("Unable to get agent socket: %s", ssh_err(r)); 2223 have_agent = 0; 2224 } 2225 } 2226 2227 /* perform the key exchange */ 2228 /* authenticate user and start session */ 2229 do_ssh2_kex(); 2230 do_authentication2(authctxt); 2231 2232 /* 2233 * If we use privilege separation, the unprivileged child transfers 2234 * the current keystate and exits 2235 */ 2236 if (use_privsep) { 2237 mm_send_keystate(pmonitor); 2238 packet_clear_keys(); 2239 exit(0); 2240 } 2241 2242 authenticated: 2243 /* 2244 * Cancel the alarm we set to limit the time taken for 2245 * authentication. 2246 */ 2247 alarm(0); 2248 signal(SIGALRM, SIG_DFL); 2249 authctxt->authenticated = 1; 2250 if (startup_pipe != -1) { 2251 close(startup_pipe); 2252 startup_pipe = -1; 2253 } 2254 2255 #ifdef SSH_AUDIT_EVENTS 2256 audit_event(SSH_AUTH_SUCCESS); 2257 #endif 2258 2259 #ifdef GSSAPI 2260 if (options.gss_authentication) { 2261 temporarily_use_uid(authctxt->pw); 2262 ssh_gssapi_storecreds(); 2263 restore_uid(); 2264 } 2265 #endif 2266 #ifdef USE_PAM 2267 if (options.use_pam) { 2268 do_pam_setcred(1); 2269 do_pam_session(ssh); 2270 } 2271 #endif 2272 2273 /* 2274 * In privilege separation, we fork another child and prepare 2275 * file descriptor passing. 2276 */ 2277 if (use_privsep) { 2278 privsep_postauth(authctxt); 2279 /* the monitor process [priv] will not return */ 2280 } 2281 2282 packet_set_timeout(options.client_alive_interval, 2283 options.client_alive_count_max); 2284 2285 /* Try to send all our hostkeys to the client */ 2286 notify_hostkeys(ssh); 2287 2288 /* Start session. */ 2289 do_authenticated(ssh, authctxt); 2290 2291 /* The connection has been terminated. */ 2292 packet_get_bytes(&ibytes, &obytes); 2293 verbose("Transferred: sent %llu, received %llu bytes", 2294 (unsigned long long)obytes, (unsigned long long)ibytes); 2295 2296 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2297 2298 #ifdef USE_PAM 2299 if (options.use_pam) 2300 finish_pam(); 2301 #endif /* USE_PAM */ 2302 2303 #ifdef SSH_AUDIT_EVENTS 2304 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2305 #endif 2306 2307 packet_close(); 2308 2309 if (use_privsep) 2310 mm_terminate(); 2311 2312 exit(0); 2313 } 2314 2315 int 2316 sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey, 2317 u_char **signature, size_t *slenp, const u_char *data, size_t dlen, 2318 const char *alg, u_int flag) 2319 { 2320 int r; 2321 2322 if (privkey) { 2323 if (PRIVSEP(sshkey_sign(privkey, signature, slenp, data, dlen, 2324 alg, datafellows)) < 0) 2325 fatal("%s: key_sign failed", __func__); 2326 } else if (use_privsep) { 2327 if (mm_sshkey_sign(pubkey, signature, slenp, data, dlen, 2328 alg, datafellows) < 0) 2329 fatal("%s: pubkey_sign failed", __func__); 2330 } else { 2331 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slenp, 2332 data, dlen, alg, datafellows)) != 0) 2333 fatal("%s: ssh_agent_sign failed: %s", 2334 __func__, ssh_err(r)); 2335 } 2336 return 0; 2337 } 2338 2339 /* SSH2 key exchange */ 2340 static void 2341 do_ssh2_kex(void) 2342 { 2343 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2344 struct kex *kex; 2345 int r; 2346 2347 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2348 options.kex_algorithms); 2349 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2350 options.ciphers); 2351 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2352 options.ciphers); 2353 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2354 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2355 2356 if (options.compression == COMP_NONE) { 2357 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2358 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2359 } 2360 2361 if (options.rekey_limit || options.rekey_interval) 2362 packet_set_rekey_limits(options.rekey_limit, 2363 options.rekey_interval); 2364 2365 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2366 list_hostkey_types()); 2367 2368 /* start key exchange */ 2369 if ((r = kex_setup(active_state, myproposal)) != 0) 2370 fatal("kex_setup: %s", ssh_err(r)); 2371 kex = active_state->kex; 2372 #ifdef WITH_OPENSSL 2373 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2374 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2375 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2376 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2377 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2378 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2379 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2380 # ifdef OPENSSL_HAS_ECC 2381 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2382 # endif 2383 #endif 2384 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2385 kex->server = 1; 2386 kex->client_version_string=client_version_string; 2387 kex->server_version_string=server_version_string; 2388 kex->load_host_public_key=&get_hostkey_public_by_type; 2389 kex->load_host_private_key=&get_hostkey_private_by_type; 2390 kex->host_key_index=&get_hostkey_index; 2391 kex->sign = sshd_hostkey_sign; 2392 2393 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done); 2394 2395 session_id2 = kex->session_id; 2396 session_id2_len = kex->session_id_len; 2397 2398 #ifdef DEBUG_KEXDH 2399 /* send 1st encrypted/maced/compressed message */ 2400 packet_start(SSH2_MSG_IGNORE); 2401 packet_put_cstring("markus"); 2402 packet_send(); 2403 packet_write_wait(); 2404 #endif 2405 debug("KEX done"); 2406 } 2407 2408 /* server specific fatal cleanup */ 2409 void 2410 cleanup_exit(int i) 2411 { 2412 struct ssh *ssh = active_state; /* XXX */ 2413 2414 if (the_authctxt) { 2415 do_cleanup(ssh, the_authctxt); 2416 if (use_privsep && privsep_is_preauth && 2417 pmonitor != NULL && pmonitor->m_pid > 1) { 2418 debug("Killing privsep child %d", pmonitor->m_pid); 2419 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2420 errno != ESRCH) 2421 error("%s: kill(%d): %s", __func__, 2422 pmonitor->m_pid, strerror(errno)); 2423 } 2424 } 2425 #ifdef SSH_AUDIT_EVENTS 2426 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2427 if (!use_privsep || mm_is_monitor()) 2428 audit_event(SSH_CONNECTION_ABANDON); 2429 #endif 2430 _exit(i); 2431 } 2432