1 /* $OpenBSD: sshd.c,v 1.492 2017/09/12 06:32:07 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 "buffer.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 "key.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 "version.h" 134 #include "ssherr.h" 135 #include "blacklist_client.h" 136 137 #ifdef LIBWRAP 138 #include <tcpd.h> 139 #include <syslog.h> 140 int allow_severity; 141 int deny_severity; 142 #endif /* LIBWRAP */ 143 144 /* Re-exec fds */ 145 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 146 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 147 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 148 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 149 150 extern char *__progname; 151 152 /* Server configuration options. */ 153 ServerOptions options; 154 155 /* Name of the server configuration file. */ 156 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 157 158 /* 159 * Debug mode flag. This can be set on the command line. If debug 160 * mode is enabled, extra debugging output will be sent to the system 161 * log, the daemon will not go to background, and will exit after processing 162 * the first connection. 163 */ 164 int debug_flag = 0; 165 166 /* Flag indicating that the daemon should only test the configuration and keys. */ 167 int test_flag = 0; 168 169 /* Flag indicating that the daemon is being started from inetd. */ 170 int inetd_flag = 0; 171 172 /* Flag indicating that sshd should not detach and become a daemon. */ 173 int no_daemon_flag = 0; 174 175 /* debug goes to stderr unless inetd_flag is set */ 176 int log_stderr = 0; 177 178 /* Saved arguments to main(). */ 179 char **saved_argv; 180 int saved_argc; 181 182 /* re-exec */ 183 int rexeced_flag = 0; 184 int rexec_flag = 1; 185 int rexec_argc = 0; 186 char **rexec_argv; 187 188 /* 189 * The sockets that the server is listening; this is used in the SIGHUP 190 * signal handler. 191 */ 192 #define MAX_LISTEN_SOCKS 16 193 int listen_socks[MAX_LISTEN_SOCKS]; 194 int num_listen_socks = 0; 195 196 /* 197 * the client's version string, passed by sshd2 in compat mode. if != NULL, 198 * sshd will skip the version-number exchange 199 */ 200 char *client_version_string = NULL; 201 char *server_version_string = NULL; 202 203 /* Daemon's agent connection */ 204 int auth_sock = -1; 205 int have_agent = 0; 206 207 /* 208 * Any really sensitive data in the application is contained in this 209 * structure. The idea is that this structure could be locked into memory so 210 * that the pages do not get written into swap. However, there are some 211 * problems. The private key contains BIGNUMs, and we do not (in principle) 212 * have access to the internals of them, and locking just the structure is 213 * not very useful. Currently, memory locking is not implemented. 214 */ 215 struct { 216 struct sshkey **host_keys; /* all private host keys */ 217 struct sshkey **host_pubkeys; /* all public host keys */ 218 struct sshkey **host_certificates; /* all public host certificates */ 219 int have_ssh2_key; 220 } sensitive_data; 221 222 /* This is set to true when a signal is received. */ 223 static volatile sig_atomic_t received_sighup = 0; 224 static volatile sig_atomic_t received_sigterm = 0; 225 226 /* session identifier, used by RSA-auth */ 227 u_char session_id[16]; 228 229 /* same for ssh2 */ 230 u_char *session_id2 = NULL; 231 u_int session_id2_len = 0; 232 233 /* record remote hostname or ip */ 234 u_int utmp_len = HOST_NAME_MAX+1; 235 236 /* options.max_startup sized array of fd ints */ 237 int *startup_pipes = NULL; 238 int startup_pipe; /* in child */ 239 240 /* variables used for privilege separation */ 241 int use_privsep = -1; 242 struct monitor *pmonitor = NULL; 243 int privsep_is_preauth = 1; 244 static int privsep_chroot = 1; 245 246 /* global authentication context */ 247 Authctxt *the_authctxt = NULL; 248 249 /* sshd_config buffer */ 250 Buffer cfg; 251 252 /* message to be displayed after login */ 253 Buffer loginmsg; 254 255 /* Unprivileged user */ 256 struct passwd *privsep_pw = NULL; 257 258 /* Prototypes for various functions defined later in this file. */ 259 void destroy_sensitive_data(void); 260 void demote_sensitive_data(void); 261 static void do_ssh2_kex(void); 262 263 /* 264 * Close all listening sockets 265 */ 266 static void 267 close_listen_socks(void) 268 { 269 int i; 270 271 for (i = 0; i < num_listen_socks; i++) 272 close(listen_socks[i]); 273 num_listen_socks = -1; 274 } 275 276 static void 277 close_startup_pipes(void) 278 { 279 int i; 280 281 if (startup_pipes) 282 for (i = 0; i < options.max_startups; i++) 283 if (startup_pipes[i] != -1) 284 close(startup_pipes[i]); 285 } 286 287 /* 288 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 289 * the effect is to reread the configuration file (and to regenerate 290 * the server key). 291 */ 292 293 /*ARGSUSED*/ 294 static void 295 sighup_handler(int sig) 296 { 297 int save_errno = errno; 298 299 received_sighup = 1; 300 signal(SIGHUP, sighup_handler); 301 errno = save_errno; 302 } 303 304 /* 305 * Called from the main program after receiving SIGHUP. 306 * Restarts the server. 307 */ 308 static void 309 sighup_restart(void) 310 { 311 logit("Received SIGHUP; restarting."); 312 if (options.pid_file != NULL) 313 unlink(options.pid_file); 314 platform_pre_restart(); 315 close_listen_socks(); 316 close_startup_pipes(); 317 alarm(0); /* alarm timer persists across exec */ 318 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 319 execv(saved_argv[0], saved_argv); 320 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 321 strerror(errno)); 322 exit(1); 323 } 324 325 /* 326 * Generic signal handler for terminating signals in the master daemon. 327 */ 328 /*ARGSUSED*/ 329 static void 330 sigterm_handler(int sig) 331 { 332 received_sigterm = sig; 333 } 334 335 /* 336 * SIGCHLD handler. This is called whenever a child dies. This will then 337 * reap any zombies left by exited children. 338 */ 339 /*ARGSUSED*/ 340 static void 341 main_sigchld_handler(int sig) 342 { 343 int save_errno = errno; 344 pid_t pid; 345 int status; 346 347 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 348 (pid < 0 && errno == EINTR)) 349 ; 350 351 signal(SIGCHLD, main_sigchld_handler); 352 errno = save_errno; 353 } 354 355 /* 356 * Signal handler for the alarm after the login grace period has expired. 357 */ 358 /*ARGSUSED*/ 359 static void 360 grace_alarm_handler(int sig) 361 { 362 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 363 kill(pmonitor->m_pid, SIGALRM); 364 365 /* 366 * Try to kill any processes that we have spawned, E.g. authorized 367 * keys command helpers. 368 */ 369 if (getpgid(0) == getpid()) { 370 signal(SIGTERM, SIG_IGN); 371 kill(0, SIGTERM); 372 } 373 374 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 375 376 /* Log error and exit. */ 377 sigdie("Timeout before authentication for %s port %d", 378 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state)); 379 } 380 381 static void 382 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) 383 { 384 u_int i; 385 int remote_major, remote_minor; 386 char *s; 387 char buf[256]; /* Must not be larger than remote_version. */ 388 char remote_version[256]; /* Must be at least as big as buf. */ 389 390 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n", 391 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION, 392 *options.version_addendum == '\0' ? "" : " ", 393 options.version_addendum); 394 395 /* Send our protocol version identification. */ 396 if (atomicio(vwrite, sock_out, server_version_string, 397 strlen(server_version_string)) 398 != strlen(server_version_string)) { 399 logit("Could not write ident string to %s port %d", 400 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 401 cleanup_exit(255); 402 } 403 404 /* Read other sides version identification. */ 405 memset(buf, 0, sizeof(buf)); 406 for (i = 0; i < sizeof(buf) - 1; i++) { 407 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 408 logit("Did not receive identification string " 409 "from %s port %d", 410 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 411 cleanup_exit(255); 412 } 413 if (buf[i] == '\r') { 414 buf[i] = 0; 415 /* Kludge for F-Secure Macintosh < 1.0.2 */ 416 if (i == 12 && 417 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 418 break; 419 continue; 420 } 421 if (buf[i] == '\n') { 422 buf[i] = 0; 423 break; 424 } 425 } 426 buf[sizeof(buf) - 1] = 0; 427 client_version_string = xstrdup(buf); 428 429 /* 430 * Check that the versions match. In future this might accept 431 * several versions and set appropriate flags to handle them. 432 */ 433 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 434 &remote_major, &remote_minor, remote_version) != 3) { 435 s = "Protocol mismatch.\n"; 436 (void) atomicio(vwrite, sock_out, s, strlen(s)); 437 logit("Bad protocol version identification '%.100s' " 438 "from %s port %d", client_version_string, 439 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 440 close(sock_in); 441 close(sock_out); 442 cleanup_exit(255); 443 } 444 debug("Client protocol version %d.%d; client software version %.100s", 445 remote_major, remote_minor, remote_version); 446 447 ssh->compat = compat_datafellows(remote_version); 448 449 if ((ssh->compat & SSH_BUG_PROBE) != 0) { 450 logit("probed from %s port %d with %s. Don't panic.", 451 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 452 client_version_string); 453 cleanup_exit(255); 454 } 455 if ((ssh->compat & SSH_BUG_SCANNER) != 0) { 456 logit("scanned 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_RSASIGMD5) != 0) { 462 logit("Client version \"%.100s\" uses unsafe RSA signature " 463 "scheme; disabling use of RSA keys", remote_version); 464 } 465 if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) { 466 fatal("Client version \"%.100s\" uses unsafe key agreement; " 467 "refusing connection", remote_version); 468 } 469 470 chop(server_version_string); 471 debug("Local version string %.200s", server_version_string); 472 473 if (remote_major != 2 || 474 (remote_major == 1 && remote_minor != 99)) { 475 s = "Protocol major versions differ.\n"; 476 (void) atomicio(vwrite, sock_out, s, strlen(s)); 477 close(sock_in); 478 close(sock_out); 479 logit("Protocol major versions differ for %s port %d: " 480 "%.200s vs. %.200s", 481 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 482 server_version_string, client_version_string); 483 cleanup_exit(255); 484 } 485 } 486 487 /* Destroy the host and server keys. They will no longer be needed. */ 488 void 489 destroy_sensitive_data(void) 490 { 491 int i; 492 493 for (i = 0; i < options.num_host_key_files; i++) { 494 if (sensitive_data.host_keys[i]) { 495 key_free(sensitive_data.host_keys[i]); 496 sensitive_data.host_keys[i] = NULL; 497 } 498 if (sensitive_data.host_certificates[i]) { 499 key_free(sensitive_data.host_certificates[i]); 500 sensitive_data.host_certificates[i] = NULL; 501 } 502 } 503 } 504 505 /* Demote private to public keys for network child */ 506 void 507 demote_sensitive_data(void) 508 { 509 struct sshkey *tmp; 510 int i; 511 512 for (i = 0; i < options.num_host_key_files; i++) { 513 if (sensitive_data.host_keys[i]) { 514 tmp = key_demote(sensitive_data.host_keys[i]); 515 key_free(sensitive_data.host_keys[i]); 516 sensitive_data.host_keys[i] = tmp; 517 } 518 /* Certs do not need demotion */ 519 } 520 } 521 522 static void 523 reseed_prngs(void) 524 { 525 u_int32_t rnd[256]; 526 527 #ifdef WITH_OPENSSL 528 RAND_poll(); 529 #endif 530 arc4random_stir(); /* noop on recent arc4random() implementations */ 531 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 532 533 #ifdef WITH_OPENSSL 534 RAND_seed(rnd, sizeof(rnd)); 535 /* give libcrypto a chance to notice the PID change */ 536 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 537 fatal("%s: RAND_bytes failed", __func__); 538 #endif 539 540 explicit_bzero(rnd, sizeof(rnd)); 541 } 542 543 static void 544 privsep_preauth_child(void) 545 { 546 gid_t gidset[1]; 547 548 /* Enable challenge-response authentication for privilege separation */ 549 privsep_challenge_enable(); 550 551 #ifdef GSSAPI 552 /* Cache supported mechanism OIDs for later use */ 553 if (options.gss_authentication) 554 ssh_gssapi_prepare_supported_oids(); 555 #endif 556 557 reseed_prngs(); 558 559 /* Demote the private keys to public keys. */ 560 demote_sensitive_data(); 561 562 /* Demote the child */ 563 if (privsep_chroot) { 564 /* Change our root directory */ 565 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 566 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 567 strerror(errno)); 568 if (chdir("/") == -1) 569 fatal("chdir(\"/\"): %s", strerror(errno)); 570 571 /* Drop our privileges */ 572 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 573 (u_int)privsep_pw->pw_gid); 574 gidset[0] = privsep_pw->pw_gid; 575 if (setgroups(1, gidset) < 0) 576 fatal("setgroups: %.100s", strerror(errno)); 577 permanently_set_uid(privsep_pw); 578 } 579 } 580 581 static int 582 privsep_preauth(Authctxt *authctxt) 583 { 584 int status, r; 585 pid_t pid; 586 struct ssh_sandbox *box = NULL; 587 588 /* Set up unprivileged child process to deal with network data */ 589 pmonitor = monitor_init(); 590 /* Store a pointer to the kex for later rekeying */ 591 pmonitor->m_pkex = &active_state->kex; 592 593 if (use_privsep == PRIVSEP_ON) 594 box = ssh_sandbox_init(pmonitor); 595 pid = fork(); 596 if (pid == -1) { 597 fatal("fork of unprivileged child failed"); 598 } else if (pid != 0) { 599 debug2("Network child is on pid %ld", (long)pid); 600 601 pmonitor->m_pid = pid; 602 if (have_agent) { 603 r = ssh_get_authentication_socket(&auth_sock); 604 if (r != 0) { 605 error("Could not get agent socket: %s", 606 ssh_err(r)); 607 have_agent = 0; 608 } 609 } 610 if (box != NULL) 611 ssh_sandbox_parent_preauth(box, pid); 612 monitor_child_preauth(authctxt, pmonitor); 613 614 /* Wait for the child's exit status */ 615 while (waitpid(pid, &status, 0) < 0) { 616 if (errno == EINTR) 617 continue; 618 pmonitor->m_pid = -1; 619 fatal("%s: waitpid: %s", __func__, strerror(errno)); 620 } 621 privsep_is_preauth = 0; 622 pmonitor->m_pid = -1; 623 if (WIFEXITED(status)) { 624 if (WEXITSTATUS(status) != 0) 625 fatal("%s: preauth child exited with status %d", 626 __func__, WEXITSTATUS(status)); 627 } else if (WIFSIGNALED(status)) 628 fatal("%s: preauth child terminated by signal %d", 629 __func__, WTERMSIG(status)); 630 if (box != NULL) 631 ssh_sandbox_parent_finish(box); 632 return 1; 633 } else { 634 /* child */ 635 close(pmonitor->m_sendfd); 636 close(pmonitor->m_log_recvfd); 637 638 /* Arrange for logging to be sent to the monitor */ 639 set_log_handler(mm_log_handler, pmonitor); 640 641 privsep_preauth_child(); 642 setproctitle("%s", "[net]"); 643 if (box != NULL) 644 ssh_sandbox_child(box); 645 646 return 0; 647 } 648 } 649 650 static void 651 privsep_postauth(Authctxt *authctxt) 652 { 653 #ifdef DISABLE_FD_PASSING 654 if (1) { 655 #else 656 if (authctxt->pw->pw_uid == 0) { 657 #endif 658 /* File descriptor passing is broken or root login */ 659 use_privsep = 0; 660 goto skip; 661 } 662 663 /* New socket pair */ 664 monitor_reinit(pmonitor); 665 666 pmonitor->m_pid = fork(); 667 if (pmonitor->m_pid == -1) 668 fatal("fork of unprivileged child failed"); 669 else if (pmonitor->m_pid != 0) { 670 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 671 buffer_clear(&loginmsg); 672 monitor_clear_keystate(pmonitor); 673 monitor_child_postauth(pmonitor); 674 675 /* NEVERREACHED */ 676 exit(0); 677 } 678 679 /* child */ 680 681 close(pmonitor->m_sendfd); 682 pmonitor->m_sendfd = -1; 683 684 /* Demote the private keys to public keys. */ 685 demote_sensitive_data(); 686 687 reseed_prngs(); 688 689 /* Drop privileges */ 690 do_setusercontext(authctxt->pw); 691 692 skip: 693 /* It is safe now to apply the key state */ 694 monitor_apply_keystate(pmonitor); 695 696 /* 697 * Tell the packet layer that authentication was successful, since 698 * this information is not part of the key state. 699 */ 700 packet_set_authenticated(); 701 } 702 703 static char * 704 list_hostkey_types(void) 705 { 706 Buffer b; 707 const char *p; 708 char *ret; 709 int i; 710 struct sshkey *key; 711 712 buffer_init(&b); 713 for (i = 0; i < options.num_host_key_files; i++) { 714 key = sensitive_data.host_keys[i]; 715 if (key == NULL) 716 key = sensitive_data.host_pubkeys[i]; 717 if (key == NULL) 718 continue; 719 /* Check that the key is accepted in HostkeyAlgorithms */ 720 if (match_pattern_list(sshkey_ssh_name(key), 721 options.hostkeyalgorithms, 0) != 1) { 722 debug3("%s: %s key not permitted by HostkeyAlgorithms", 723 __func__, sshkey_ssh_name(key)); 724 continue; 725 } 726 switch (key->type) { 727 case KEY_RSA: 728 case KEY_DSA: 729 case KEY_ECDSA: 730 case KEY_ED25519: 731 if (buffer_len(&b) > 0) 732 buffer_append(&b, ",", 1); 733 p = key_ssh_name(key); 734 buffer_append(&b, p, strlen(p)); 735 736 /* for RSA we also support SHA2 signatures */ 737 if (key->type == KEY_RSA) { 738 p = ",rsa-sha2-512,rsa-sha2-256"; 739 buffer_append(&b, p, strlen(p)); 740 } 741 break; 742 } 743 /* If the private key has a cert peer, then list that too */ 744 key = sensitive_data.host_certificates[i]; 745 if (key == NULL) 746 continue; 747 switch (key->type) { 748 case KEY_RSA_CERT: 749 case KEY_DSA_CERT: 750 case KEY_ECDSA_CERT: 751 case KEY_ED25519_CERT: 752 if (buffer_len(&b) > 0) 753 buffer_append(&b, ",", 1); 754 p = key_ssh_name(key); 755 buffer_append(&b, p, strlen(p)); 756 break; 757 } 758 } 759 if ((ret = sshbuf_dup_string(&b)) == NULL) 760 fatal("%s: sshbuf_dup_string failed", __func__); 761 buffer_free(&b); 762 debug("list_hostkey_types: %s", ret); 763 return ret; 764 } 765 766 static struct sshkey * 767 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 768 { 769 int i; 770 struct sshkey *key; 771 772 for (i = 0; i < options.num_host_key_files; i++) { 773 switch (type) { 774 case KEY_RSA_CERT: 775 case KEY_DSA_CERT: 776 case KEY_ECDSA_CERT: 777 case KEY_ED25519_CERT: 778 key = sensitive_data.host_certificates[i]; 779 break; 780 default: 781 key = sensitive_data.host_keys[i]; 782 if (key == NULL && !need_private) 783 key = sensitive_data.host_pubkeys[i]; 784 break; 785 } 786 if (key != NULL && key->type == type && 787 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 788 return need_private ? 789 sensitive_data.host_keys[i] : key; 790 } 791 return NULL; 792 } 793 794 struct sshkey * 795 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 796 { 797 return get_hostkey_by_type(type, nid, 0, ssh); 798 } 799 800 struct sshkey * 801 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 802 { 803 return get_hostkey_by_type(type, nid, 1, ssh); 804 } 805 806 struct sshkey * 807 get_hostkey_by_index(int ind) 808 { 809 if (ind < 0 || ind >= options.num_host_key_files) 810 return (NULL); 811 return (sensitive_data.host_keys[ind]); 812 } 813 814 struct sshkey * 815 get_hostkey_public_by_index(int ind, struct ssh *ssh) 816 { 817 if (ind < 0 || ind >= options.num_host_key_files) 818 return (NULL); 819 return (sensitive_data.host_pubkeys[ind]); 820 } 821 822 int 823 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 824 { 825 int i; 826 827 for (i = 0; i < options.num_host_key_files; i++) { 828 if (key_is_cert(key)) { 829 if (key == sensitive_data.host_certificates[i] || 830 (compare && sensitive_data.host_certificates[i] && 831 sshkey_equal(key, 832 sensitive_data.host_certificates[i]))) 833 return (i); 834 } else { 835 if (key == sensitive_data.host_keys[i] || 836 (compare && sensitive_data.host_keys[i] && 837 sshkey_equal(key, sensitive_data.host_keys[i]))) 838 return (i); 839 if (key == sensitive_data.host_pubkeys[i] || 840 (compare && sensitive_data.host_pubkeys[i] && 841 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 842 return (i); 843 } 844 } 845 return (-1); 846 } 847 848 /* Inform the client of all hostkeys */ 849 static void 850 notify_hostkeys(struct ssh *ssh) 851 { 852 struct sshbuf *buf; 853 struct sshkey *key; 854 int i, nkeys, r; 855 char *fp; 856 857 /* Some clients cannot cope with the hostkeys message, skip those. */ 858 if (datafellows & SSH_BUG_HOSTKEYS) 859 return; 860 861 if ((buf = sshbuf_new()) == NULL) 862 fatal("%s: sshbuf_new", __func__); 863 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 864 key = get_hostkey_public_by_index(i, ssh); 865 if (key == NULL || key->type == KEY_UNSPEC || 866 sshkey_is_cert(key)) 867 continue; 868 fp = sshkey_fingerprint(key, options.fingerprint_hash, 869 SSH_FP_DEFAULT); 870 debug3("%s: key %d: %s %s", __func__, i, 871 sshkey_ssh_name(key), fp); 872 free(fp); 873 if (nkeys == 0) { 874 packet_start(SSH2_MSG_GLOBAL_REQUEST); 875 packet_put_cstring("hostkeys-00@openssh.com"); 876 packet_put_char(0); /* want-reply */ 877 } 878 sshbuf_reset(buf); 879 if ((r = sshkey_putb(key, buf)) != 0) 880 fatal("%s: couldn't put hostkey %d: %s", 881 __func__, i, ssh_err(r)); 882 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 883 nkeys++; 884 } 885 debug3("%s: sent %d hostkeys", __func__, nkeys); 886 if (nkeys == 0) 887 fatal("%s: no hostkeys", __func__); 888 packet_send(); 889 sshbuf_free(buf); 890 } 891 892 /* 893 * returns 1 if connection should be dropped, 0 otherwise. 894 * dropping starts at connection #max_startups_begin with a probability 895 * of (max_startups_rate/100). the probability increases linearly until 896 * all connections are dropped for startups > max_startups 897 */ 898 static int 899 drop_connection(int startups) 900 { 901 int p, r; 902 903 if (startups < options.max_startups_begin) 904 return 0; 905 if (startups >= options.max_startups) 906 return 1; 907 if (options.max_startups_rate == 100) 908 return 1; 909 910 p = 100 - options.max_startups_rate; 911 p *= startups - options.max_startups_begin; 912 p /= options.max_startups - options.max_startups_begin; 913 p += options.max_startups_rate; 914 r = arc4random_uniform(100); 915 916 debug("drop_connection: p %d, r %d", p, r); 917 return (r < p) ? 1 : 0; 918 } 919 920 static void 921 usage(void) 922 { 923 if (options.version_addendum && *options.version_addendum != '\0') 924 fprintf(stderr, "%s %s, %s\n", 925 SSH_RELEASE, 926 options.version_addendum, OPENSSL_VERSION); 927 else 928 fprintf(stderr, "%s, %s\n", 929 SSH_RELEASE, OPENSSL_VERSION); 930 fprintf(stderr, 931 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 932 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 933 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 934 ); 935 exit(1); 936 } 937 938 static void 939 send_rexec_state(int fd, struct sshbuf *conf) 940 { 941 struct sshbuf *m; 942 int r; 943 944 debug3("%s: entering fd = %d config len %zu", __func__, fd, 945 sshbuf_len(conf)); 946 947 /* 948 * Protocol from reexec master to child: 949 * string configuration 950 * string rngseed (only if OpenSSL is not self-seeded) 951 */ 952 if ((m = sshbuf_new()) == NULL) 953 fatal("%s: sshbuf_new failed", __func__); 954 if ((r = sshbuf_put_stringb(m, conf)) != 0) 955 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 956 957 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 958 rexec_send_rng_seed(m); 959 #endif 960 961 if (ssh_msg_send(fd, 0, m) == -1) 962 fatal("%s: ssh_msg_send failed", __func__); 963 964 sshbuf_free(m); 965 966 debug3("%s: done", __func__); 967 } 968 969 static void 970 recv_rexec_state(int fd, Buffer *conf) 971 { 972 Buffer m; 973 char *cp; 974 u_int len; 975 976 debug3("%s: entering fd = %d", __func__, fd); 977 978 buffer_init(&m); 979 980 if (ssh_msg_recv(fd, &m) == -1) 981 fatal("%s: ssh_msg_recv failed", __func__); 982 if (buffer_get_char(&m) != 0) 983 fatal("%s: rexec version mismatch", __func__); 984 985 cp = buffer_get_string(&m, &len); 986 if (conf != NULL) 987 buffer_append(conf, cp, len); 988 free(cp); 989 990 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 991 rexec_recv_rng_seed(&m); 992 #endif 993 994 buffer_free(&m); 995 996 debug3("%s: done", __func__); 997 } 998 999 /* Accept a connection from inetd */ 1000 static void 1001 server_accept_inetd(int *sock_in, int *sock_out) 1002 { 1003 int fd; 1004 1005 startup_pipe = -1; 1006 if (rexeced_flag) { 1007 close(REEXEC_CONFIG_PASS_FD); 1008 *sock_in = *sock_out = dup(STDIN_FILENO); 1009 if (!debug_flag) { 1010 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1011 close(REEXEC_STARTUP_PIPE_FD); 1012 } 1013 } else { 1014 *sock_in = dup(STDIN_FILENO); 1015 *sock_out = dup(STDOUT_FILENO); 1016 } 1017 /* 1018 * We intentionally do not close the descriptors 0, 1, and 2 1019 * as our code for setting the descriptors won't work if 1020 * ttyfd happens to be one of those. 1021 */ 1022 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1023 dup2(fd, STDIN_FILENO); 1024 dup2(fd, STDOUT_FILENO); 1025 if (!log_stderr) 1026 dup2(fd, STDERR_FILENO); 1027 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1028 close(fd); 1029 } 1030 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1031 } 1032 1033 /* 1034 * Listen for TCP connections 1035 */ 1036 static void 1037 server_listen(void) 1038 { 1039 int ret, listen_sock, on = 1; 1040 struct addrinfo *ai; 1041 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1042 int socksize; 1043 socklen_t len; 1044 1045 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1046 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1047 continue; 1048 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1049 fatal("Too many listen sockets. " 1050 "Enlarge MAX_LISTEN_SOCKS"); 1051 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1052 ntop, sizeof(ntop), strport, sizeof(strport), 1053 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1054 error("getnameinfo failed: %.100s", 1055 ssh_gai_strerror(ret)); 1056 continue; 1057 } 1058 /* Create socket for listening. */ 1059 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1060 ai->ai_protocol); 1061 if (listen_sock < 0) { 1062 /* kernel may not support ipv6 */ 1063 verbose("socket: %.100s", strerror(errno)); 1064 continue; 1065 } 1066 if (set_nonblock(listen_sock) == -1) { 1067 close(listen_sock); 1068 continue; 1069 } 1070 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1071 verbose("socket: CLOEXEC: %s", strerror(errno)); 1072 close(listen_sock); 1073 continue; 1074 } 1075 /* 1076 * Set socket options. 1077 * Allow local port reuse in TIME_WAIT. 1078 */ 1079 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1080 &on, sizeof(on)) == -1) 1081 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1082 1083 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1084 if (ai->ai_family == AF_INET6) 1085 sock_set_v6only(listen_sock); 1086 1087 debug("Bind to port %s on %s.", strport, ntop); 1088 1089 len = sizeof(socksize); 1090 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1091 debug("Server TCP RWIN socket size: %d", socksize); 1092 1093 /* Bind the socket to the desired port. */ 1094 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1095 error("Bind to port %s on %s failed: %.200s.", 1096 strport, ntop, strerror(errno)); 1097 close(listen_sock); 1098 continue; 1099 } 1100 listen_socks[num_listen_socks] = listen_sock; 1101 num_listen_socks++; 1102 1103 /* Start listening on the port. */ 1104 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1105 fatal("listen on [%s]:%s: %.100s", 1106 ntop, strport, strerror(errno)); 1107 logit("Server listening on %s port %s.", ntop, strport); 1108 } 1109 freeaddrinfo(options.listen_addrs); 1110 1111 if (!num_listen_socks) 1112 fatal("Cannot bind any address."); 1113 } 1114 1115 /* 1116 * The main TCP accept loop. Note that, for the non-debug case, returns 1117 * from this function are in a forked subprocess. 1118 */ 1119 static void 1120 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1121 { 1122 fd_set *fdset; 1123 int i, j, ret, maxfd; 1124 int startups = 0; 1125 int startup_p[2] = { -1 , -1 }; 1126 struct sockaddr_storage from; 1127 socklen_t fromlen; 1128 pid_t pid; 1129 u_char rnd[256]; 1130 1131 /* setup fd set for accept */ 1132 fdset = NULL; 1133 maxfd = 0; 1134 for (i = 0; i < num_listen_socks; i++) 1135 if (listen_socks[i] > maxfd) 1136 maxfd = listen_socks[i]; 1137 /* pipes connected to unauthenticated childs */ 1138 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1139 for (i = 0; i < options.max_startups; i++) 1140 startup_pipes[i] = -1; 1141 1142 /* 1143 * Stay listening for connections until the system crashes or 1144 * the daemon is killed with a signal. 1145 */ 1146 for (;;) { 1147 if (received_sighup) 1148 sighup_restart(); 1149 free(fdset); 1150 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1151 sizeof(fd_mask)); 1152 1153 for (i = 0; i < num_listen_socks; i++) 1154 FD_SET(listen_socks[i], fdset); 1155 for (i = 0; i < options.max_startups; i++) 1156 if (startup_pipes[i] != -1) 1157 FD_SET(startup_pipes[i], fdset); 1158 1159 /* Wait in select until there is a connection. */ 1160 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1161 if (ret < 0 && errno != EINTR) 1162 error("select: %.100s", strerror(errno)); 1163 if (received_sigterm) { 1164 logit("Received signal %d; terminating.", 1165 (int) received_sigterm); 1166 close_listen_socks(); 1167 if (options.pid_file != NULL) 1168 unlink(options.pid_file); 1169 exit(received_sigterm == SIGTERM ? 0 : 255); 1170 } 1171 if (ret < 0) 1172 continue; 1173 1174 for (i = 0; i < options.max_startups; i++) 1175 if (startup_pipes[i] != -1 && 1176 FD_ISSET(startup_pipes[i], fdset)) { 1177 /* 1178 * the read end of the pipe is ready 1179 * if the child has closed the pipe 1180 * after successful authentication 1181 * or if the child has died 1182 */ 1183 close(startup_pipes[i]); 1184 startup_pipes[i] = -1; 1185 startups--; 1186 } 1187 for (i = 0; i < num_listen_socks; i++) { 1188 if (!FD_ISSET(listen_socks[i], fdset)) 1189 continue; 1190 fromlen = sizeof(from); 1191 *newsock = accept(listen_socks[i], 1192 (struct sockaddr *)&from, &fromlen); 1193 if (*newsock < 0) { 1194 if (errno != EINTR && errno != EWOULDBLOCK && 1195 errno != ECONNABORTED && errno != EAGAIN) 1196 error("accept: %.100s", 1197 strerror(errno)); 1198 if (errno == EMFILE || errno == ENFILE) 1199 usleep(100 * 1000); 1200 continue; 1201 } 1202 if (unset_nonblock(*newsock) == -1) { 1203 close(*newsock); 1204 continue; 1205 } 1206 if (drop_connection(startups) == 1) { 1207 char *laddr = get_local_ipaddr(*newsock); 1208 char *raddr = get_peer_ipaddr(*newsock); 1209 1210 verbose("drop connection #%d from [%s]:%d " 1211 "on [%s]:%d past MaxStartups", startups, 1212 raddr, get_peer_port(*newsock), 1213 laddr, get_local_port(*newsock)); 1214 free(laddr); 1215 free(raddr); 1216 close(*newsock); 1217 continue; 1218 } 1219 if (pipe(startup_p) == -1) { 1220 close(*newsock); 1221 continue; 1222 } 1223 1224 if (rexec_flag && socketpair(AF_UNIX, 1225 SOCK_STREAM, 0, config_s) == -1) { 1226 error("reexec socketpair: %s", 1227 strerror(errno)); 1228 close(*newsock); 1229 close(startup_p[0]); 1230 close(startup_p[1]); 1231 continue; 1232 } 1233 1234 for (j = 0; j < options.max_startups; j++) 1235 if (startup_pipes[j] == -1) { 1236 startup_pipes[j] = startup_p[0]; 1237 if (maxfd < startup_p[0]) 1238 maxfd = startup_p[0]; 1239 startups++; 1240 break; 1241 } 1242 1243 /* 1244 * Got connection. Fork a child to handle it, unless 1245 * we are in debugging mode. 1246 */ 1247 if (debug_flag) { 1248 /* 1249 * In debugging mode. Close the listening 1250 * socket, and start processing the 1251 * connection without forking. 1252 */ 1253 debug("Server will not fork when running in debugging mode."); 1254 close_listen_socks(); 1255 *sock_in = *newsock; 1256 *sock_out = *newsock; 1257 close(startup_p[0]); 1258 close(startup_p[1]); 1259 startup_pipe = -1; 1260 pid = getpid(); 1261 if (rexec_flag) { 1262 send_rexec_state(config_s[0], 1263 &cfg); 1264 close(config_s[0]); 1265 } 1266 break; 1267 } 1268 1269 /* 1270 * Normal production daemon. Fork, and have 1271 * the child process the connection. The 1272 * parent continues listening. 1273 */ 1274 platform_pre_fork(); 1275 if ((pid = fork()) == 0) { 1276 /* 1277 * Child. Close the listening and 1278 * max_startup sockets. Start using 1279 * the accepted socket. Reinitialize 1280 * logging (since our pid has changed). 1281 * We break out of the loop to handle 1282 * the connection. 1283 */ 1284 platform_post_fork_child(); 1285 startup_pipe = startup_p[1]; 1286 close_startup_pipes(); 1287 close_listen_socks(); 1288 *sock_in = *newsock; 1289 *sock_out = *newsock; 1290 log_init(__progname, 1291 options.log_level, 1292 options.log_facility, 1293 log_stderr); 1294 if (rexec_flag) 1295 close(config_s[0]); 1296 break; 1297 } 1298 1299 /* Parent. Stay in the loop. */ 1300 platform_post_fork_parent(pid); 1301 if (pid < 0) 1302 error("fork: %.100s", strerror(errno)); 1303 else 1304 debug("Forked child %ld.", (long)pid); 1305 1306 close(startup_p[1]); 1307 1308 if (rexec_flag) { 1309 send_rexec_state(config_s[0], &cfg); 1310 close(config_s[0]); 1311 close(config_s[1]); 1312 } 1313 close(*newsock); 1314 1315 /* 1316 * Ensure that our random state differs 1317 * from that of the child 1318 */ 1319 arc4random_stir(); 1320 arc4random_buf(rnd, sizeof(rnd)); 1321 #ifdef WITH_OPENSSL 1322 RAND_seed(rnd, sizeof(rnd)); 1323 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1324 fatal("%s: RAND_bytes failed", __func__); 1325 #endif 1326 explicit_bzero(rnd, sizeof(rnd)); 1327 } 1328 1329 /* child process check (or debug mode) */ 1330 if (num_listen_socks < 0) 1331 break; 1332 } 1333 } 1334 1335 /* 1336 * If IP options are supported, make sure there are none (log and 1337 * return an error if any are found). Basically we are worried about 1338 * source routing; it can be used to pretend you are somebody 1339 * (ip-address) you are not. That itself may be "almost acceptable" 1340 * under certain circumstances, but rhosts autentication is useless 1341 * if source routing is accepted. Notice also that if we just dropped 1342 * source routing here, the other side could use IP spoofing to do 1343 * rest of the interaction and could still bypass security. So we 1344 * exit here if we detect any IP options. 1345 */ 1346 static void 1347 check_ip_options(struct ssh *ssh) 1348 { 1349 #ifdef IP_OPTIONS 1350 int sock_in = ssh_packet_get_connection_in(ssh); 1351 struct sockaddr_storage from; 1352 u_char opts[200]; 1353 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1354 char text[sizeof(opts) * 3 + 1]; 1355 1356 memset(&from, 0, sizeof(from)); 1357 if (getpeername(sock_in, (struct sockaddr *)&from, 1358 &fromlen) < 0) 1359 return; 1360 if (from.ss_family != AF_INET) 1361 return; 1362 /* XXX IPv6 options? */ 1363 1364 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1365 &option_size) >= 0 && option_size != 0) { 1366 text[0] = '\0'; 1367 for (i = 0; i < option_size; i++) 1368 snprintf(text + i*3, sizeof(text) - i*3, 1369 " %2.2x", opts[i]); 1370 fatal("Connection from %.100s port %d with IP opts: %.800s", 1371 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1372 } 1373 return; 1374 #endif /* IP_OPTIONS */ 1375 } 1376 1377 /* 1378 * Main program for the daemon. 1379 */ 1380 int 1381 main(int ac, char **av) 1382 { 1383 struct ssh *ssh = NULL; 1384 extern char *optarg; 1385 extern int optind; 1386 int r, opt, i, j, on = 1, already_daemon; 1387 int sock_in = -1, sock_out = -1, newsock = -1; 1388 const char *remote_ip; 1389 int remote_port; 1390 char *fp, *line, *laddr, *logfile = NULL; 1391 int config_s[2] = { -1 , -1 }; 1392 u_int n; 1393 u_int64_t ibytes, obytes; 1394 mode_t new_umask; 1395 struct sshkey *key; 1396 struct sshkey *pubkey; 1397 int keytype; 1398 Authctxt *authctxt; 1399 struct connection_info *connection_info = get_connection_info(0, 0); 1400 1401 ssh_malloc_init(); /* must be called before any mallocs */ 1402 1403 #ifdef HAVE_SECUREWARE 1404 (void)set_auth_parameters(ac, av); 1405 #endif 1406 __progname = ssh_get_progname(av[0]); 1407 1408 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1409 saved_argc = ac; 1410 rexec_argc = ac; 1411 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1412 for (i = 0; i < ac; i++) 1413 saved_argv[i] = xstrdup(av[i]); 1414 saved_argv[i] = NULL; 1415 1416 #ifndef HAVE_SETPROCTITLE 1417 /* Prepare for later setproctitle emulation */ 1418 compat_init_setproctitle(ac, av); 1419 av = saved_argv; 1420 #endif 1421 1422 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1423 debug("setgroups(): %.200s", strerror(errno)); 1424 1425 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1426 sanitise_stdfd(); 1427 1428 /* Initialize configuration options to their default values. */ 1429 initialize_server_options(&options); 1430 1431 /* Parse command-line arguments. */ 1432 while ((opt = getopt(ac, av, 1433 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1434 switch (opt) { 1435 case '4': 1436 options.address_family = AF_INET; 1437 break; 1438 case '6': 1439 options.address_family = AF_INET6; 1440 break; 1441 case 'f': 1442 config_file_name = optarg; 1443 break; 1444 case 'c': 1445 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1446 fprintf(stderr, "too many host certificates.\n"); 1447 exit(1); 1448 } 1449 options.host_cert_files[options.num_host_cert_files++] = 1450 derelativise_path(optarg); 1451 break; 1452 case 'd': 1453 if (debug_flag == 0) { 1454 debug_flag = 1; 1455 options.log_level = SYSLOG_LEVEL_DEBUG1; 1456 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1457 options.log_level++; 1458 break; 1459 case 'D': 1460 no_daemon_flag = 1; 1461 break; 1462 case 'E': 1463 logfile = optarg; 1464 /* FALLTHROUGH */ 1465 case 'e': 1466 log_stderr = 1; 1467 break; 1468 case 'i': 1469 inetd_flag = 1; 1470 break; 1471 case 'r': 1472 rexec_flag = 0; 1473 break; 1474 case 'R': 1475 rexeced_flag = 1; 1476 inetd_flag = 1; 1477 break; 1478 case 'Q': 1479 /* ignored */ 1480 break; 1481 case 'q': 1482 options.log_level = SYSLOG_LEVEL_QUIET; 1483 break; 1484 case 'b': 1485 /* protocol 1, ignored */ 1486 break; 1487 case 'p': 1488 options.ports_from_cmdline = 1; 1489 if (options.num_ports >= MAX_PORTS) { 1490 fprintf(stderr, "too many ports.\n"); 1491 exit(1); 1492 } 1493 options.ports[options.num_ports++] = a2port(optarg); 1494 if (options.ports[options.num_ports-1] <= 0) { 1495 fprintf(stderr, "Bad port number.\n"); 1496 exit(1); 1497 } 1498 break; 1499 case 'g': 1500 if ((options.login_grace_time = convtime(optarg)) == -1) { 1501 fprintf(stderr, "Invalid login grace time.\n"); 1502 exit(1); 1503 } 1504 break; 1505 case 'k': 1506 /* protocol 1, ignored */ 1507 break; 1508 case 'h': 1509 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1510 fprintf(stderr, "too many host keys.\n"); 1511 exit(1); 1512 } 1513 options.host_key_files[options.num_host_key_files++] = 1514 derelativise_path(optarg); 1515 break; 1516 case 't': 1517 test_flag = 1; 1518 break; 1519 case 'T': 1520 test_flag = 2; 1521 break; 1522 case 'C': 1523 if (parse_server_match_testspec(connection_info, 1524 optarg) == -1) 1525 exit(1); 1526 break; 1527 case 'u': 1528 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1529 if (utmp_len > HOST_NAME_MAX+1) { 1530 fprintf(stderr, "Invalid utmp length.\n"); 1531 exit(1); 1532 } 1533 break; 1534 case 'o': 1535 line = xstrdup(optarg); 1536 if (process_server_config_line(&options, line, 1537 "command-line", 0, NULL, NULL) != 0) 1538 exit(1); 1539 free(line); 1540 break; 1541 case '?': 1542 default: 1543 usage(); 1544 break; 1545 } 1546 } 1547 if (rexeced_flag || inetd_flag) 1548 rexec_flag = 0; 1549 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1550 fatal("sshd re-exec requires execution with an absolute path"); 1551 if (rexeced_flag) 1552 closefrom(REEXEC_MIN_FREE_FD); 1553 else 1554 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1555 1556 #ifdef WITH_OPENSSL 1557 OpenSSL_add_all_algorithms(); 1558 #endif 1559 1560 /* If requested, redirect the logs to the specified logfile. */ 1561 if (logfile != NULL) 1562 log_redirect_stderr_to(logfile); 1563 /* 1564 * Force logging to stderr until we have loaded the private host 1565 * key (unless started from inetd) 1566 */ 1567 log_init(__progname, 1568 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1569 SYSLOG_LEVEL_INFO : options.log_level, 1570 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1571 SYSLOG_FACILITY_AUTH : options.log_facility, 1572 log_stderr || !inetd_flag); 1573 1574 /* 1575 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1576 * root's environment 1577 */ 1578 if (getenv("KRB5CCNAME") != NULL) 1579 (void) unsetenv("KRB5CCNAME"); 1580 1581 #ifdef _UNICOS 1582 /* Cray can define user privs drop all privs now! 1583 * Not needed on PRIV_SU systems! 1584 */ 1585 drop_cray_privs(); 1586 #endif 1587 1588 sensitive_data.have_ssh2_key = 0; 1589 1590 /* 1591 * If we're doing an extended config test, make sure we have all of 1592 * the parameters we need. If we're not doing an extended test, 1593 * do not silently ignore connection test params. 1594 */ 1595 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1596 fatal("user, host and addr are all required when testing " 1597 "Match configs"); 1598 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1599 fatal("Config test connection parameter (-C) provided without " 1600 "test mode (-T)"); 1601 1602 /* Fetch our configuration */ 1603 buffer_init(&cfg); 1604 if (rexeced_flag) 1605 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1606 else if (strcasecmp(config_file_name, "none") != 0) 1607 load_server_config(config_file_name, &cfg); 1608 1609 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1610 &cfg, NULL); 1611 1612 seed_rng(); 1613 1614 /* Fill in default values for those options not explicitly set. */ 1615 fill_default_server_options(&options); 1616 1617 /* challenge-response is implemented via keyboard interactive */ 1618 if (options.challenge_response_authentication) 1619 options.kbd_interactive_authentication = 1; 1620 1621 /* Check that options are sensible */ 1622 if (options.authorized_keys_command_user == NULL && 1623 (options.authorized_keys_command != NULL && 1624 strcasecmp(options.authorized_keys_command, "none") != 0)) 1625 fatal("AuthorizedKeysCommand set without " 1626 "AuthorizedKeysCommandUser"); 1627 if (options.authorized_principals_command_user == NULL && 1628 (options.authorized_principals_command != NULL && 1629 strcasecmp(options.authorized_principals_command, "none") != 0)) 1630 fatal("AuthorizedPrincipalsCommand set without " 1631 "AuthorizedPrincipalsCommandUser"); 1632 1633 /* 1634 * Check whether there is any path through configured auth methods. 1635 * Unfortunately it is not possible to verify this generally before 1636 * daemonisation in the presence of Match block, but this catches 1637 * and warns for trivial misconfigurations that could break login. 1638 */ 1639 if (options.num_auth_methods != 0) { 1640 for (n = 0; n < options.num_auth_methods; n++) { 1641 if (auth2_methods_valid(options.auth_methods[n], 1642 1) == 0) 1643 break; 1644 } 1645 if (n >= options.num_auth_methods) 1646 fatal("AuthenticationMethods cannot be satisfied by " 1647 "enabled authentication methods"); 1648 } 1649 1650 /* Check that there are no remaining arguments. */ 1651 if (optind < ac) { 1652 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1653 exit(1); 1654 } 1655 1656 debug("sshd version %s, %s", SSH_VERSION, 1657 #ifdef WITH_OPENSSL 1658 SSLeay_version(SSLEAY_VERSION) 1659 #else 1660 "without OpenSSL" 1661 #endif 1662 ); 1663 1664 /* Store privilege separation user for later use if required. */ 1665 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); 1666 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1667 if (privsep_chroot || options.kerberos_authentication) 1668 fatal("Privilege separation user %s does not exist", 1669 SSH_PRIVSEP_USER); 1670 } else { 1671 explicit_bzero(privsep_pw->pw_passwd, 1672 strlen(privsep_pw->pw_passwd)); 1673 privsep_pw = pwcopy(privsep_pw); 1674 free(privsep_pw->pw_passwd); 1675 privsep_pw->pw_passwd = xstrdup("*"); 1676 } 1677 endpwent(); 1678 1679 /* load host keys */ 1680 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1681 sizeof(struct sshkey *)); 1682 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1683 sizeof(struct sshkey *)); 1684 1685 if (options.host_key_agent) { 1686 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1687 setenv(SSH_AUTHSOCKET_ENV_NAME, 1688 options.host_key_agent, 1); 1689 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1690 have_agent = 1; 1691 else 1692 error("Could not connect to agent \"%s\": %s", 1693 options.host_key_agent, ssh_err(r)); 1694 } 1695 1696 for (i = 0; i < options.num_host_key_files; i++) { 1697 if (options.host_key_files[i] == NULL) 1698 continue; 1699 key = key_load_private(options.host_key_files[i], "", NULL); 1700 pubkey = key_load_public(options.host_key_files[i], NULL); 1701 1702 if (pubkey == NULL && key != NULL) 1703 pubkey = key_demote(key); 1704 sensitive_data.host_keys[i] = key; 1705 sensitive_data.host_pubkeys[i] = pubkey; 1706 1707 if (key == NULL && pubkey != NULL && have_agent) { 1708 debug("will rely on agent for hostkey %s", 1709 options.host_key_files[i]); 1710 keytype = pubkey->type; 1711 } else if (key != NULL) { 1712 keytype = key->type; 1713 } else { 1714 error("Could not load host key: %s", 1715 options.host_key_files[i]); 1716 sensitive_data.host_keys[i] = NULL; 1717 sensitive_data.host_pubkeys[i] = NULL; 1718 continue; 1719 } 1720 1721 switch (keytype) { 1722 case KEY_RSA: 1723 case KEY_DSA: 1724 case KEY_ECDSA: 1725 case KEY_ED25519: 1726 if (have_agent || key != NULL) 1727 sensitive_data.have_ssh2_key = 1; 1728 break; 1729 } 1730 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1731 SSH_FP_DEFAULT)) == NULL) 1732 fatal("sshkey_fingerprint failed"); 1733 debug("%s host key #%d: %s %s", 1734 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1735 free(fp); 1736 } 1737 if (!sensitive_data.have_ssh2_key) { 1738 logit("sshd: no hostkeys available -- exiting."); 1739 exit(1); 1740 } 1741 1742 /* 1743 * Load certificates. They are stored in an array at identical 1744 * indices to the public keys that they relate to. 1745 */ 1746 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1747 sizeof(struct sshkey *)); 1748 for (i = 0; i < options.num_host_key_files; i++) 1749 sensitive_data.host_certificates[i] = NULL; 1750 1751 for (i = 0; i < options.num_host_cert_files; i++) { 1752 if (options.host_cert_files[i] == NULL) 1753 continue; 1754 key = key_load_public(options.host_cert_files[i], NULL); 1755 if (key == NULL) { 1756 error("Could not load host certificate: %s", 1757 options.host_cert_files[i]); 1758 continue; 1759 } 1760 if (!key_is_cert(key)) { 1761 error("Certificate file is not a certificate: %s", 1762 options.host_cert_files[i]); 1763 key_free(key); 1764 continue; 1765 } 1766 /* Find matching private key */ 1767 for (j = 0; j < options.num_host_key_files; j++) { 1768 if (key_equal_public(key, 1769 sensitive_data.host_keys[j])) { 1770 sensitive_data.host_certificates[j] = key; 1771 break; 1772 } 1773 } 1774 if (j >= options.num_host_key_files) { 1775 error("No matching private key for certificate: %s", 1776 options.host_cert_files[i]); 1777 key_free(key); 1778 continue; 1779 } 1780 sensitive_data.host_certificates[j] = key; 1781 debug("host certificate: #%d type %d %s", j, key->type, 1782 key_type(key)); 1783 } 1784 1785 if (privsep_chroot) { 1786 struct stat st; 1787 1788 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1789 (S_ISDIR(st.st_mode) == 0)) 1790 fatal("Missing privilege separation directory: %s", 1791 _PATH_PRIVSEP_CHROOT_DIR); 1792 1793 #ifdef HAVE_CYGWIN 1794 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1795 (st.st_uid != getuid () || 1796 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1797 #else 1798 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1799 #endif 1800 fatal("%s must be owned by root and not group or " 1801 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1802 } 1803 1804 if (test_flag > 1) { 1805 if (server_match_spec_complete(connection_info) == 1) 1806 parse_server_match_config(&options, connection_info); 1807 dump_config(&options); 1808 } 1809 1810 /* Configuration looks good, so exit if in test mode. */ 1811 if (test_flag) 1812 exit(0); 1813 1814 /* 1815 * Clear out any supplemental groups we may have inherited. This 1816 * prevents inadvertent creation of files with bad modes (in the 1817 * portable version at least, it's certainly possible for PAM 1818 * to create a file, and we can't control the code in every 1819 * module which might be used). 1820 */ 1821 if (setgroups(0, NULL) < 0) 1822 debug("setgroups() failed: %.200s", strerror(errno)); 1823 1824 if (rexec_flag) { 1825 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1826 for (i = 0; i < rexec_argc; i++) { 1827 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1828 rexec_argv[i] = saved_argv[i]; 1829 } 1830 rexec_argv[rexec_argc] = "-R"; 1831 rexec_argv[rexec_argc + 1] = NULL; 1832 } 1833 1834 /* Ensure that umask disallows at least group and world write */ 1835 new_umask = umask(0077) | 0022; 1836 (void) umask(new_umask); 1837 1838 /* Initialize the log (it is reinitialized below in case we forked). */ 1839 if (debug_flag && (!inetd_flag || rexeced_flag)) 1840 log_stderr = 1; 1841 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1842 1843 /* 1844 * If not in debugging mode, not started from inetd and not already 1845 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1846 * terminal, and fork. The original process exits. 1847 */ 1848 already_daemon = daemonized(); 1849 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1850 1851 if (daemon(0, 0) < 0) 1852 fatal("daemon() failed: %.200s", strerror(errno)); 1853 1854 disconnect_controlling_tty(); 1855 } 1856 /* Reinitialize the log (because of the fork above). */ 1857 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1858 1859 /* Avoid killing the process in high-pressure swapping environments. */ 1860 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1861 debug("madvise(): %.200s", strerror(errno)); 1862 1863 /* Chdir to the root directory so that the current disk can be 1864 unmounted if desired. */ 1865 if (chdir("/") == -1) 1866 error("chdir(\"/\"): %s", strerror(errno)); 1867 1868 /* ignore SIGPIPE */ 1869 signal(SIGPIPE, SIG_IGN); 1870 1871 /* Get a connection, either from inetd or a listening TCP socket */ 1872 if (inetd_flag) { 1873 server_accept_inetd(&sock_in, &sock_out); 1874 } else { 1875 platform_pre_listen(); 1876 server_listen(); 1877 1878 signal(SIGHUP, sighup_handler); 1879 signal(SIGCHLD, main_sigchld_handler); 1880 signal(SIGTERM, sigterm_handler); 1881 signal(SIGQUIT, sigterm_handler); 1882 1883 /* 1884 * Write out the pid file after the sigterm handler 1885 * is setup and the listen sockets are bound 1886 */ 1887 if (options.pid_file != NULL && !debug_flag) { 1888 FILE *f = fopen(options.pid_file, "w"); 1889 1890 if (f == NULL) { 1891 error("Couldn't create pid file \"%s\": %s", 1892 options.pid_file, strerror(errno)); 1893 } else { 1894 fprintf(f, "%ld\n", (long) getpid()); 1895 fclose(f); 1896 } 1897 } 1898 1899 /* Accept a connection and return in a forked child */ 1900 server_accept_loop(&sock_in, &sock_out, 1901 &newsock, config_s); 1902 } 1903 1904 /* This is the child processing a new connection. */ 1905 setproctitle("%s", "[accepted]"); 1906 1907 /* 1908 * Create a new session and process group since the 4.4BSD 1909 * setlogin() affects the entire process group. We don't 1910 * want the child to be able to affect the parent. 1911 */ 1912 #if !defined(SSHD_ACQUIRES_CTTY) 1913 /* 1914 * If setsid is called, on some platforms sshd will later acquire a 1915 * controlling terminal which will result in "could not set 1916 * controlling tty" errors. 1917 */ 1918 if (!debug_flag && !inetd_flag && setsid() < 0) 1919 error("setsid: %.100s", strerror(errno)); 1920 #endif 1921 1922 if (rexec_flag) { 1923 int fd; 1924 1925 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1926 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1927 dup2(newsock, STDIN_FILENO); 1928 dup2(STDIN_FILENO, STDOUT_FILENO); 1929 if (startup_pipe == -1) 1930 close(REEXEC_STARTUP_PIPE_FD); 1931 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1932 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1933 close(startup_pipe); 1934 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1935 } 1936 1937 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1938 close(config_s[1]); 1939 1940 execv(rexec_argv[0], rexec_argv); 1941 1942 /* Reexec has failed, fall back and continue */ 1943 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1944 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1945 log_init(__progname, options.log_level, 1946 options.log_facility, log_stderr); 1947 1948 /* Clean up fds */ 1949 close(REEXEC_CONFIG_PASS_FD); 1950 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1951 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1952 dup2(fd, STDIN_FILENO); 1953 dup2(fd, STDOUT_FILENO); 1954 if (fd > STDERR_FILENO) 1955 close(fd); 1956 } 1957 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1958 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1959 } 1960 1961 /* Executed child processes don't need these. */ 1962 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1963 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1964 1965 /* 1966 * Disable the key regeneration alarm. We will not regenerate the 1967 * key since we are no longer in a position to give it to anyone. We 1968 * will not restart on SIGHUP since it no longer makes sense. 1969 */ 1970 alarm(0); 1971 signal(SIGALRM, SIG_DFL); 1972 signal(SIGHUP, SIG_DFL); 1973 signal(SIGTERM, SIG_DFL); 1974 signal(SIGQUIT, SIG_DFL); 1975 signal(SIGCHLD, SIG_DFL); 1976 signal(SIGINT, SIG_DFL); 1977 1978 #ifdef __FreeBSD__ 1979 /* 1980 * Initialize the resolver. This may not happen automatically 1981 * before privsep chroot(). 1982 */ 1983 if ((_res.options & RES_INIT) == 0) { 1984 debug("res_init()"); 1985 res_init(); 1986 } 1987 #ifdef GSSAPI 1988 /* 1989 * Force GSS-API to parse its configuration and load any 1990 * mechanism plugins. 1991 */ 1992 { 1993 gss_OID_set mechs; 1994 OM_uint32 minor_status; 1995 gss_indicate_mechs(&minor_status, &mechs); 1996 gss_release_oid_set(&minor_status, &mechs); 1997 } 1998 #endif 1999 #endif 2000 2001 /* 2002 * Register our connection. This turns encryption off because we do 2003 * not have a key. 2004 */ 2005 packet_set_connection(sock_in, sock_out); 2006 packet_set_server(); 2007 ssh = active_state; /* XXX */ 2008 2009 check_ip_options(ssh); 2010 2011 /* Prepare the channels layer */ 2012 channel_init_channels(ssh); 2013 channel_set_af(ssh, options.address_family); 2014 process_permitopen(ssh, &options); 2015 2016 /* Set SO_KEEPALIVE if requested. */ 2017 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2018 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2019 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2020 2021 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2022 debug("ssh_remote_port failed"); 2023 cleanup_exit(255); 2024 } 2025 2026 /* 2027 * The rest of the code depends on the fact that 2028 * ssh_remote_ipaddr() caches the remote ip, even if 2029 * the socket goes away. 2030 */ 2031 remote_ip = ssh_remote_ipaddr(ssh); 2032 2033 #ifdef SSH_AUDIT_EVENTS 2034 audit_connection_from(remote_ip, remote_port); 2035 #endif 2036 #ifdef LIBWRAP 2037 allow_severity = options.log_facility|LOG_INFO; 2038 deny_severity = options.log_facility|LOG_WARNING; 2039 /* Check whether logins are denied from this host. */ 2040 if (packet_connection_is_on_socket()) { 2041 struct request_info req; 2042 2043 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2044 fromhost(&req); 2045 2046 if (!hosts_access(&req)) { 2047 debug("Connection refused by tcp wrapper"); 2048 refuse(&req); 2049 /* NOTREACHED */ 2050 fatal("libwrap refuse returns"); 2051 } 2052 } 2053 #endif /* LIBWRAP */ 2054 2055 /* Log the connection. */ 2056 laddr = get_local_ipaddr(sock_in); 2057 verbose("Connection from %s port %d on %s port %d", 2058 remote_ip, remote_port, laddr, ssh_local_port(ssh)); 2059 free(laddr); 2060 2061 /* 2062 * We don't want to listen forever unless the other side 2063 * successfully authenticates itself. So we set up an alarm which is 2064 * cleared after successful authentication. A limit of zero 2065 * indicates no limit. Note that we don't set the alarm in debugging 2066 * mode; it is just annoying to have the server exit just when you 2067 * are about to discover the bug. 2068 */ 2069 signal(SIGALRM, grace_alarm_handler); 2070 if (!debug_flag) 2071 alarm(options.login_grace_time); 2072 2073 sshd_exchange_identification(ssh, sock_in, sock_out); 2074 packet_set_nonblocking(); 2075 2076 /* allocate authentication context */ 2077 authctxt = xcalloc(1, sizeof(*authctxt)); 2078 2079 authctxt->loginmsg = &loginmsg; 2080 2081 /* XXX global for cleanup, access from other modules */ 2082 the_authctxt = authctxt; 2083 2084 /* prepare buffer to collect messages to display to user after login */ 2085 buffer_init(&loginmsg); 2086 auth_debug_reset(); 2087 2088 BLACKLIST_INIT(); 2089 2090 if (use_privsep) { 2091 if (privsep_preauth(authctxt) == 1) 2092 goto authenticated; 2093 } else if (have_agent) { 2094 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2095 error("Unable to get agent socket: %s", ssh_err(r)); 2096 have_agent = 0; 2097 } 2098 } 2099 2100 /* perform the key exchange */ 2101 /* authenticate user and start session */ 2102 do_ssh2_kex(); 2103 do_authentication2(authctxt); 2104 2105 /* 2106 * If we use privilege separation, the unprivileged child transfers 2107 * the current keystate and exits 2108 */ 2109 if (use_privsep) { 2110 mm_send_keystate(pmonitor); 2111 packet_clear_keys(); 2112 exit(0); 2113 } 2114 2115 authenticated: 2116 /* 2117 * Cancel the alarm we set to limit the time taken for 2118 * authentication. 2119 */ 2120 alarm(0); 2121 signal(SIGALRM, SIG_DFL); 2122 authctxt->authenticated = 1; 2123 if (startup_pipe != -1) { 2124 close(startup_pipe); 2125 startup_pipe = -1; 2126 } 2127 2128 #ifdef SSH_AUDIT_EVENTS 2129 audit_event(SSH_AUTH_SUCCESS); 2130 #endif 2131 2132 #ifdef GSSAPI 2133 if (options.gss_authentication) { 2134 temporarily_use_uid(authctxt->pw); 2135 ssh_gssapi_storecreds(); 2136 restore_uid(); 2137 } 2138 #endif 2139 #ifdef USE_PAM 2140 if (options.use_pam) { 2141 do_pam_setcred(1); 2142 do_pam_session(); 2143 } 2144 #endif 2145 2146 /* 2147 * In privilege separation, we fork another child and prepare 2148 * file descriptor passing. 2149 */ 2150 if (use_privsep) { 2151 privsep_postauth(authctxt); 2152 /* the monitor process [priv] will not return */ 2153 } 2154 2155 packet_set_timeout(options.client_alive_interval, 2156 options.client_alive_count_max); 2157 2158 /* Try to send all our hostkeys to the client */ 2159 notify_hostkeys(ssh); 2160 2161 /* Start session. */ 2162 do_authenticated(ssh, authctxt); 2163 2164 /* The connection has been terminated. */ 2165 packet_get_bytes(&ibytes, &obytes); 2166 verbose("Transferred: sent %llu, received %llu bytes", 2167 (unsigned long long)obytes, (unsigned long long)ibytes); 2168 2169 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2170 2171 #ifdef USE_PAM 2172 if (options.use_pam) 2173 finish_pam(); 2174 #endif /* USE_PAM */ 2175 2176 #ifdef SSH_AUDIT_EVENTS 2177 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2178 #endif 2179 2180 packet_close(); 2181 2182 if (use_privsep) 2183 mm_terminate(); 2184 2185 exit(0); 2186 } 2187 2188 int 2189 sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey, 2190 u_char **signature, size_t *slen, const u_char *data, size_t dlen, 2191 const char *alg, u_int flag) 2192 { 2193 int r; 2194 u_int xxx_slen, xxx_dlen = dlen; 2195 2196 if (privkey) { 2197 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen, 2198 alg) < 0)) 2199 fatal("%s: key_sign failed", __func__); 2200 if (slen) 2201 *slen = xxx_slen; 2202 } else if (use_privsep) { 2203 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen, 2204 alg) < 0) 2205 fatal("%s: pubkey_sign failed", __func__); 2206 if (slen) 2207 *slen = xxx_slen; 2208 } else { 2209 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2210 data, dlen, alg, datafellows)) != 0) 2211 fatal("%s: ssh_agent_sign failed: %s", 2212 __func__, ssh_err(r)); 2213 } 2214 return 0; 2215 } 2216 2217 /* SSH2 key exchange */ 2218 static void 2219 do_ssh2_kex(void) 2220 { 2221 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2222 struct kex *kex; 2223 int r; 2224 2225 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2226 options.kex_algorithms); 2227 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2228 options.ciphers); 2229 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2230 options.ciphers); 2231 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2232 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2233 2234 if (options.compression == COMP_NONE) { 2235 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2236 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2237 } 2238 2239 if (options.rekey_limit || options.rekey_interval) 2240 packet_set_rekey_limits(options.rekey_limit, 2241 options.rekey_interval); 2242 2243 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2244 list_hostkey_types()); 2245 2246 /* start key exchange */ 2247 if ((r = kex_setup(active_state, myproposal)) != 0) 2248 fatal("kex_setup: %s", ssh_err(r)); 2249 kex = active_state->kex; 2250 #ifdef WITH_OPENSSL 2251 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2252 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2253 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2254 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2255 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2256 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2257 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2258 # ifdef OPENSSL_HAS_ECC 2259 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2260 # endif 2261 #endif 2262 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2263 kex->server = 1; 2264 kex->client_version_string=client_version_string; 2265 kex->server_version_string=server_version_string; 2266 kex->load_host_public_key=&get_hostkey_public_by_type; 2267 kex->load_host_private_key=&get_hostkey_private_by_type; 2268 kex->host_key_index=&get_hostkey_index; 2269 kex->sign = sshd_hostkey_sign; 2270 2271 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done); 2272 2273 session_id2 = kex->session_id; 2274 session_id2_len = kex->session_id_len; 2275 2276 #ifdef DEBUG_KEXDH 2277 /* send 1st encrypted/maced/compressed message */ 2278 packet_start(SSH2_MSG_IGNORE); 2279 packet_put_cstring("markus"); 2280 packet_send(); 2281 packet_write_wait(); 2282 #endif 2283 debug("KEX done"); 2284 } 2285 2286 /* server specific fatal cleanup */ 2287 void 2288 cleanup_exit(int i) 2289 { 2290 struct ssh *ssh = active_state; /* XXX */ 2291 2292 if (the_authctxt) { 2293 do_cleanup(ssh, the_authctxt); 2294 if (use_privsep && privsep_is_preauth && 2295 pmonitor != NULL && pmonitor->m_pid > 1) { 2296 debug("Killing privsep child %d", pmonitor->m_pid); 2297 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2298 errno != ESRCH) 2299 error("%s: kill(%d): %s", __func__, 2300 pmonitor->m_pid, strerror(errno)); 2301 } 2302 } 2303 #ifdef SSH_AUDIT_EVENTS 2304 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2305 if (!use_privsep || mm_is_monitor()) 2306 audit_event(SSH_CONNECTION_ABANDON); 2307 #endif 2308 _exit(i); 2309 } 2310