1 /* $OpenBSD: sshd.c,v 1.485 2017/03/15 03:52:30 deraadt 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 "rsa.h" 103 #include "sshpty.h" 104 #include "packet.h" 105 #include "log.h" 106 #include "buffer.h" 107 #include "misc.h" 108 #include "match.h" 109 #include "servconf.h" 110 #include "uidswap.h" 111 #include "compat.h" 112 #include "cipher.h" 113 #include "digest.h" 114 #include "key.h" 115 #include "kex.h" 116 #include "myproposal.h" 117 #include "authfile.h" 118 #include "pathnames.h" 119 #include "atomicio.h" 120 #include "canohost.h" 121 #include "hostfile.h" 122 #include "auth.h" 123 #include "authfd.h" 124 #include "msg.h" 125 #include "dispatch.h" 126 #include "channels.h" 127 #include "session.h" 128 #include "monitor.h" 129 #ifdef GSSAPI 130 #include "ssh-gss.h" 131 #endif 132 #include "monitor_wrap.h" 133 #include "ssh-sandbox.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 /* Flag indicating that the daemon should only test the configuration and keys. */ 168 int test_flag = 0; 169 170 /* Flag indicating that the daemon is being started from inetd. */ 171 int inetd_flag = 0; 172 173 /* Flag indicating that sshd should not detach and become a daemon. */ 174 int no_daemon_flag = 0; 175 176 /* debug goes to stderr unless inetd_flag is set */ 177 int log_stderr = 0; 178 179 /* Saved arguments to main(). */ 180 char **saved_argv; 181 int saved_argc; 182 183 /* re-exec */ 184 int rexeced_flag = 0; 185 int rexec_flag = 1; 186 int rexec_argc = 0; 187 char **rexec_argv; 188 189 /* 190 * The sockets that the server is listening; this is used in the SIGHUP 191 * signal handler. 192 */ 193 #define MAX_LISTEN_SOCKS 16 194 int listen_socks[MAX_LISTEN_SOCKS]; 195 int num_listen_socks = 0; 196 197 /* 198 * the client's version string, passed by sshd2 in compat mode. if != NULL, 199 * sshd will skip the version-number exchange 200 */ 201 char *client_version_string = NULL; 202 char *server_version_string = NULL; 203 204 /* Daemon's agent connection */ 205 int auth_sock = -1; 206 int have_agent = 0; 207 208 /* 209 * Any really sensitive data in the application is contained in this 210 * structure. The idea is that this structure could be locked into memory so 211 * that the pages do not get written into swap. However, there are some 212 * problems. The private key contains BIGNUMs, and we do not (in principle) 213 * have access to the internals of them, and locking just the structure is 214 * not very useful. Currently, memory locking is not implemented. 215 */ 216 struct { 217 Key **host_keys; /* all private host keys */ 218 Key **host_pubkeys; /* all public host keys */ 219 Key **host_certificates; /* all public host certificates */ 220 int have_ssh2_key; 221 } sensitive_data; 222 223 /* This is set to true when a signal is received. */ 224 static volatile sig_atomic_t received_sighup = 0; 225 static volatile sig_atomic_t received_sigterm = 0; 226 227 /* session identifier, used by RSA-auth */ 228 u_char session_id[16]; 229 230 /* same for ssh2 */ 231 u_char *session_id2 = NULL; 232 u_int session_id2_len = 0; 233 234 /* record remote hostname or ip */ 235 u_int utmp_len = HOST_NAME_MAX+1; 236 237 /* options.max_startup sized array of fd ints */ 238 int *startup_pipes = NULL; 239 int startup_pipe; /* in child */ 240 241 /* variables used for privilege separation */ 242 int use_privsep = -1; 243 struct monitor *pmonitor = NULL; 244 int privsep_is_preauth = 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 enable_compat20(); 476 } else { 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 int i; 494 495 for (i = 0; i < options.num_host_key_files; i++) { 496 if (sensitive_data.host_keys[i]) { 497 key_free(sensitive_data.host_keys[i]); 498 sensitive_data.host_keys[i] = NULL; 499 } 500 if (sensitive_data.host_certificates[i]) { 501 key_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 Key *tmp; 512 int i; 513 514 for (i = 0; i < options.num_host_key_files; i++) { 515 if (sensitive_data.host_keys[i]) { 516 tmp = key_demote(sensitive_data.host_keys[i]); 517 key_free(sensitive_data.host_keys[i]); 518 sensitive_data.host_keys[i] = tmp; 519 } 520 /* Certs do not need demotion */ 521 } 522 } 523 524 static void 525 reseed_prngs(void) 526 { 527 u_int32_t rnd[256]; 528 529 #ifdef WITH_OPENSSL 530 RAND_poll(); 531 #endif 532 arc4random_stir(); /* noop on recent arc4random() implementations */ 533 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 534 535 #ifdef WITH_OPENSSL 536 RAND_seed(rnd, sizeof(rnd)); 537 /* give libcrypto a chance to notice the PID change */ 538 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 539 fatal("%s: RAND_bytes failed", __func__); 540 #endif 541 542 explicit_bzero(rnd, sizeof(rnd)); 543 } 544 545 static void 546 privsep_preauth_child(void) 547 { 548 gid_t gidset[1]; 549 550 /* Enable challenge-response authentication for privilege separation */ 551 privsep_challenge_enable(); 552 553 #ifdef GSSAPI 554 /* Cache supported mechanism OIDs for later use */ 555 if (options.gss_authentication) 556 ssh_gssapi_prepare_supported_oids(); 557 #endif 558 559 reseed_prngs(); 560 561 /* Demote the private keys to public keys. */ 562 demote_sensitive_data(); 563 564 /* Demote the child */ 565 if (getuid() == 0 || geteuid() == 0) { 566 /* Change our root directory */ 567 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 568 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 569 strerror(errno)); 570 if (chdir("/") == -1) 571 fatal("chdir(\"/\"): %s", strerror(errno)); 572 573 /* Drop our privileges */ 574 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 575 (u_int)privsep_pw->pw_gid); 576 gidset[0] = privsep_pw->pw_gid; 577 if (setgroups(1, gidset) < 0) 578 fatal("setgroups: %.100s", strerror(errno)); 579 permanently_set_uid(privsep_pw); 580 } 581 } 582 583 static int 584 privsep_preauth(Authctxt *authctxt) 585 { 586 int status, r; 587 pid_t pid; 588 struct ssh_sandbox *box = NULL; 589 590 /* Set up unprivileged child process to deal with network data */ 591 pmonitor = monitor_init(); 592 /* Store a pointer to the kex for later rekeying */ 593 pmonitor->m_pkex = &active_state->kex; 594 595 if (use_privsep == PRIVSEP_ON) 596 box = ssh_sandbox_init(pmonitor); 597 pid = fork(); 598 if (pid == -1) { 599 fatal("fork of unprivileged child failed"); 600 } else if (pid != 0) { 601 debug2("Network child is on pid %ld", (long)pid); 602 603 pmonitor->m_pid = pid; 604 if (have_agent) { 605 r = ssh_get_authentication_socket(&auth_sock); 606 if (r != 0) { 607 error("Could not get agent socket: %s", 608 ssh_err(r)); 609 have_agent = 0; 610 } 611 } 612 if (box != NULL) 613 ssh_sandbox_parent_preauth(box, pid); 614 monitor_child_preauth(authctxt, pmonitor); 615 616 /* Wait for the child's exit status */ 617 while (waitpid(pid, &status, 0) < 0) { 618 if (errno == EINTR) 619 continue; 620 pmonitor->m_pid = -1; 621 fatal("%s: waitpid: %s", __func__, strerror(errno)); 622 } 623 privsep_is_preauth = 0; 624 pmonitor->m_pid = -1; 625 if (WIFEXITED(status)) { 626 if (WEXITSTATUS(status) != 0) 627 fatal("%s: preauth child exited with status %d", 628 __func__, WEXITSTATUS(status)); 629 } else if (WIFSIGNALED(status)) 630 fatal("%s: preauth child terminated by signal %d", 631 __func__, WTERMSIG(status)); 632 if (box != NULL) 633 ssh_sandbox_parent_finish(box); 634 return 1; 635 } else { 636 /* child */ 637 close(pmonitor->m_sendfd); 638 close(pmonitor->m_log_recvfd); 639 640 /* Arrange for logging to be sent to the monitor */ 641 set_log_handler(mm_log_handler, pmonitor); 642 643 privsep_preauth_child(); 644 setproctitle("%s", "[net]"); 645 if (box != NULL) 646 ssh_sandbox_child(box); 647 648 return 0; 649 } 650 } 651 652 static void 653 privsep_postauth(Authctxt *authctxt) 654 { 655 #ifdef DISABLE_FD_PASSING 656 if (1) { 657 #else 658 if (authctxt->pw->pw_uid == 0) { 659 #endif 660 /* File descriptor passing is broken or root login */ 661 use_privsep = 0; 662 goto skip; 663 } 664 665 /* New socket pair */ 666 monitor_reinit(pmonitor); 667 668 pmonitor->m_pid = fork(); 669 if (pmonitor->m_pid == -1) 670 fatal("fork of unprivileged child failed"); 671 else if (pmonitor->m_pid != 0) { 672 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 673 buffer_clear(&loginmsg); 674 monitor_child_postauth(pmonitor); 675 676 /* NEVERREACHED */ 677 exit(0); 678 } 679 680 /* child */ 681 682 close(pmonitor->m_sendfd); 683 pmonitor->m_sendfd = -1; 684 685 /* Demote the private keys to public keys. */ 686 demote_sensitive_data(); 687 688 reseed_prngs(); 689 690 /* Drop privileges */ 691 do_setusercontext(authctxt->pw); 692 693 skip: 694 /* It is safe now to apply the key state */ 695 monitor_apply_keystate(pmonitor); 696 697 /* 698 * Tell the packet layer that authentication was successful, since 699 * this information is not part of the key state. 700 */ 701 packet_set_authenticated(); 702 } 703 704 static char * 705 list_hostkey_types(void) 706 { 707 Buffer b; 708 const char *p; 709 char *ret; 710 int i; 711 Key *key; 712 713 buffer_init(&b); 714 for (i = 0; i < options.num_host_key_files; i++) { 715 key = sensitive_data.host_keys[i]; 716 if (key == NULL) 717 key = sensitive_data.host_pubkeys[i]; 718 if (key == NULL) 719 continue; 720 /* Check that the key is accepted in HostkeyAlgorithms */ 721 if (match_pattern_list(sshkey_ssh_name(key), 722 options.hostkeyalgorithms, 0) != 1) { 723 debug3("%s: %s key not permitted by HostkeyAlgorithms", 724 __func__, sshkey_ssh_name(key)); 725 continue; 726 } 727 switch (key->type) { 728 case KEY_RSA: 729 case KEY_DSA: 730 case KEY_ECDSA: 731 case KEY_ED25519: 732 if (buffer_len(&b) > 0) 733 buffer_append(&b, ",", 1); 734 p = key_ssh_name(key); 735 buffer_append(&b, p, strlen(p)); 736 737 /* for RSA we also support SHA2 signatures */ 738 if (key->type == KEY_RSA) { 739 p = ",rsa-sha2-512,rsa-sha2-256"; 740 buffer_append(&b, p, strlen(p)); 741 } 742 break; 743 } 744 /* If the private key has a cert peer, then list that too */ 745 key = sensitive_data.host_certificates[i]; 746 if (key == NULL) 747 continue; 748 switch (key->type) { 749 case KEY_RSA_CERT: 750 case KEY_DSA_CERT: 751 case KEY_ECDSA_CERT: 752 case KEY_ED25519_CERT: 753 if (buffer_len(&b) > 0) 754 buffer_append(&b, ",", 1); 755 p = key_ssh_name(key); 756 buffer_append(&b, p, strlen(p)); 757 break; 758 } 759 } 760 if ((ret = sshbuf_dup_string(&b)) == NULL) 761 fatal("%s: sshbuf_dup_string failed", __func__); 762 buffer_free(&b); 763 debug("list_hostkey_types: %s", ret); 764 return ret; 765 } 766 767 static Key * 768 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 769 { 770 int i; 771 Key *key; 772 773 for (i = 0; i < options.num_host_key_files; i++) { 774 switch (type) { 775 case KEY_RSA_CERT: 776 case KEY_DSA_CERT: 777 case KEY_ECDSA_CERT: 778 case KEY_ED25519_CERT: 779 key = sensitive_data.host_certificates[i]; 780 break; 781 default: 782 key = sensitive_data.host_keys[i]; 783 if (key == NULL && !need_private) 784 key = sensitive_data.host_pubkeys[i]; 785 break; 786 } 787 if (key != NULL && key->type == type && 788 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 789 return need_private ? 790 sensitive_data.host_keys[i] : key; 791 } 792 return NULL; 793 } 794 795 Key * 796 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 797 { 798 return get_hostkey_by_type(type, nid, 0, ssh); 799 } 800 801 Key * 802 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 803 { 804 return get_hostkey_by_type(type, nid, 1, ssh); 805 } 806 807 Key * 808 get_hostkey_by_index(int ind) 809 { 810 if (ind < 0 || ind >= options.num_host_key_files) 811 return (NULL); 812 return (sensitive_data.host_keys[ind]); 813 } 814 815 Key * 816 get_hostkey_public_by_index(int ind, struct ssh *ssh) 817 { 818 if (ind < 0 || ind >= options.num_host_key_files) 819 return (NULL); 820 return (sensitive_data.host_pubkeys[ind]); 821 } 822 823 int 824 get_hostkey_index(Key *key, int compare, struct ssh *ssh) 825 { 826 int i; 827 828 for (i = 0; i < options.num_host_key_files; i++) { 829 if (key_is_cert(key)) { 830 if (key == sensitive_data.host_certificates[i] || 831 (compare && sensitive_data.host_certificates[i] && 832 sshkey_equal(key, 833 sensitive_data.host_certificates[i]))) 834 return (i); 835 } else { 836 if (key == sensitive_data.host_keys[i] || 837 (compare && sensitive_data.host_keys[i] && 838 sshkey_equal(key, sensitive_data.host_keys[i]))) 839 return (i); 840 if (key == sensitive_data.host_pubkeys[i] || 841 (compare && sensitive_data.host_pubkeys[i] && 842 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 843 return (i); 844 } 845 } 846 return (-1); 847 } 848 849 /* Inform the client of all hostkeys */ 850 static void 851 notify_hostkeys(struct ssh *ssh) 852 { 853 struct sshbuf *buf; 854 struct sshkey *key; 855 int i, nkeys, r; 856 char *fp; 857 858 /* Some clients cannot cope with the hostkeys message, skip those. */ 859 if (datafellows & SSH_BUG_HOSTKEYS) 860 return; 861 862 if ((buf = sshbuf_new()) == NULL) 863 fatal("%s: sshbuf_new", __func__); 864 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 865 key = get_hostkey_public_by_index(i, ssh); 866 if (key == NULL || key->type == KEY_UNSPEC || 867 sshkey_is_cert(key)) 868 continue; 869 fp = sshkey_fingerprint(key, options.fingerprint_hash, 870 SSH_FP_DEFAULT); 871 debug3("%s: key %d: %s %s", __func__, i, 872 sshkey_ssh_name(key), fp); 873 free(fp); 874 if (nkeys == 0) { 875 packet_start(SSH2_MSG_GLOBAL_REQUEST); 876 packet_put_cstring("hostkeys-00@openssh.com"); 877 packet_put_char(0); /* want-reply */ 878 } 879 sshbuf_reset(buf); 880 if ((r = sshkey_putb(key, buf)) != 0) 881 fatal("%s: couldn't put hostkey %d: %s", 882 __func__, i, ssh_err(r)); 883 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 884 nkeys++; 885 } 886 debug3("%s: sent %d hostkeys", __func__, nkeys); 887 if (nkeys == 0) 888 fatal("%s: no hostkeys", __func__); 889 packet_send(); 890 sshbuf_free(buf); 891 } 892 893 /* 894 * returns 1 if connection should be dropped, 0 otherwise. 895 * dropping starts at connection #max_startups_begin with a probability 896 * of (max_startups_rate/100). the probability increases linearly until 897 * all connections are dropped for startups > max_startups 898 */ 899 static int 900 drop_connection(int startups) 901 { 902 int p, r; 903 904 if (startups < options.max_startups_begin) 905 return 0; 906 if (startups >= options.max_startups) 907 return 1; 908 if (options.max_startups_rate == 100) 909 return 1; 910 911 p = 100 - options.max_startups_rate; 912 p *= startups - options.max_startups_begin; 913 p /= options.max_startups - options.max_startups_begin; 914 p += options.max_startups_rate; 915 r = arc4random_uniform(100); 916 917 debug("drop_connection: p %d, r %d", p, r); 918 return (r < p) ? 1 : 0; 919 } 920 921 static void 922 usage(void) 923 { 924 if (options.version_addendum && *options.version_addendum != '\0') 925 fprintf(stderr, "%s %s, %s\n", 926 SSH_RELEASE, 927 options.version_addendum, OPENSSL_VERSION); 928 else 929 fprintf(stderr, "%s, %s\n", 930 SSH_RELEASE, OPENSSL_VERSION); 931 fprintf(stderr, 932 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 933 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 934 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 935 ); 936 exit(1); 937 } 938 939 static void 940 send_rexec_state(int fd, struct sshbuf *conf) 941 { 942 struct sshbuf *m; 943 int r; 944 945 debug3("%s: entering fd = %d config len %zu", __func__, fd, 946 sshbuf_len(conf)); 947 948 /* 949 * Protocol from reexec master to child: 950 * string configuration 951 * string rngseed (only if OpenSSL is not self-seeded) 952 */ 953 if ((m = sshbuf_new()) == NULL) 954 fatal("%s: sshbuf_new failed", __func__); 955 if ((r = sshbuf_put_stringb(m, conf)) != 0) 956 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 957 958 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 959 rexec_send_rng_seed(m); 960 #endif 961 962 if (ssh_msg_send(fd, 0, m) == -1) 963 fatal("%s: ssh_msg_send failed", __func__); 964 965 sshbuf_free(m); 966 967 debug3("%s: done", __func__); 968 } 969 970 static void 971 recv_rexec_state(int fd, Buffer *conf) 972 { 973 Buffer m; 974 char *cp; 975 u_int len; 976 977 debug3("%s: entering fd = %d", __func__, fd); 978 979 buffer_init(&m); 980 981 if (ssh_msg_recv(fd, &m) == -1) 982 fatal("%s: ssh_msg_recv failed", __func__); 983 if (buffer_get_char(&m) != 0) 984 fatal("%s: rexec version mismatch", __func__); 985 986 cp = buffer_get_string(&m, &len); 987 if (conf != NULL) 988 buffer_append(conf, cp, len); 989 free(cp); 990 991 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 992 rexec_recv_rng_seed(&m); 993 #endif 994 995 buffer_free(&m); 996 997 debug3("%s: done", __func__); 998 } 999 1000 /* Accept a connection from inetd */ 1001 static void 1002 server_accept_inetd(int *sock_in, int *sock_out) 1003 { 1004 int fd; 1005 1006 startup_pipe = -1; 1007 if (rexeced_flag) { 1008 close(REEXEC_CONFIG_PASS_FD); 1009 *sock_in = *sock_out = dup(STDIN_FILENO); 1010 if (!debug_flag) { 1011 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1012 close(REEXEC_STARTUP_PIPE_FD); 1013 } 1014 } else { 1015 *sock_in = dup(STDIN_FILENO); 1016 *sock_out = dup(STDOUT_FILENO); 1017 } 1018 /* 1019 * We intentionally do not close the descriptors 0, 1, and 2 1020 * as our code for setting the descriptors won't work if 1021 * ttyfd happens to be one of those. 1022 */ 1023 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1024 dup2(fd, STDIN_FILENO); 1025 dup2(fd, STDOUT_FILENO); 1026 if (!log_stderr) 1027 dup2(fd, STDERR_FILENO); 1028 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1029 close(fd); 1030 } 1031 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1032 } 1033 1034 /* 1035 * Listen for TCP connections 1036 */ 1037 static void 1038 server_listen(void) 1039 { 1040 int ret, listen_sock, on = 1; 1041 struct addrinfo *ai; 1042 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1043 int socksize; 1044 socklen_t len; 1045 1046 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1047 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1048 continue; 1049 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1050 fatal("Too many listen sockets. " 1051 "Enlarge MAX_LISTEN_SOCKS"); 1052 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1053 ntop, sizeof(ntop), strport, sizeof(strport), 1054 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1055 error("getnameinfo failed: %.100s", 1056 ssh_gai_strerror(ret)); 1057 continue; 1058 } 1059 /* Create socket for listening. */ 1060 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1061 ai->ai_protocol); 1062 if (listen_sock < 0) { 1063 /* kernel may not support ipv6 */ 1064 verbose("socket: %.100s", strerror(errno)); 1065 continue; 1066 } 1067 if (set_nonblock(listen_sock) == -1) { 1068 close(listen_sock); 1069 continue; 1070 } 1071 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1072 verbose("socket: CLOEXEC: %s", strerror(errno)); 1073 close(listen_sock); 1074 continue; 1075 } 1076 /* 1077 * Set socket options. 1078 * Allow local port reuse in TIME_WAIT. 1079 */ 1080 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1081 &on, sizeof(on)) == -1) 1082 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1083 1084 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1085 if (ai->ai_family == AF_INET6) 1086 sock_set_v6only(listen_sock); 1087 1088 debug("Bind to port %s on %s.", strport, ntop); 1089 1090 len = sizeof(socksize); 1091 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1092 debug("Server TCP RWIN socket size: %d", socksize); 1093 1094 /* Bind the socket to the desired port. */ 1095 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1096 error("Bind to port %s on %s failed: %.200s.", 1097 strport, ntop, strerror(errno)); 1098 close(listen_sock); 1099 continue; 1100 } 1101 listen_socks[num_listen_socks] = listen_sock; 1102 num_listen_socks++; 1103 1104 /* Start listening on the port. */ 1105 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1106 fatal("listen on [%s]:%s: %.100s", 1107 ntop, strport, strerror(errno)); 1108 logit("Server listening on %s port %s.", ntop, strport); 1109 } 1110 freeaddrinfo(options.listen_addrs); 1111 1112 if (!num_listen_socks) 1113 fatal("Cannot bind any address."); 1114 } 1115 1116 /* 1117 * The main TCP accept loop. Note that, for the non-debug case, returns 1118 * from this function are in a forked subprocess. 1119 */ 1120 static void 1121 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1122 { 1123 fd_set *fdset; 1124 int i, j, ret, maxfd; 1125 int startups = 0; 1126 int startup_p[2] = { -1 , -1 }; 1127 struct sockaddr_storage from; 1128 socklen_t fromlen; 1129 pid_t pid; 1130 u_char rnd[256]; 1131 1132 /* setup fd set for accept */ 1133 fdset = NULL; 1134 maxfd = 0; 1135 for (i = 0; i < num_listen_socks; i++) 1136 if (listen_socks[i] > maxfd) 1137 maxfd = listen_socks[i]; 1138 /* pipes connected to unauthenticated childs */ 1139 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1140 for (i = 0; i < options.max_startups; i++) 1141 startup_pipes[i] = -1; 1142 1143 /* 1144 * Stay listening for connections until the system crashes or 1145 * the daemon is killed with a signal. 1146 */ 1147 for (;;) { 1148 if (received_sighup) 1149 sighup_restart(); 1150 free(fdset); 1151 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1152 sizeof(fd_mask)); 1153 1154 for (i = 0; i < num_listen_socks; i++) 1155 FD_SET(listen_socks[i], fdset); 1156 for (i = 0; i < options.max_startups; i++) 1157 if (startup_pipes[i] != -1) 1158 FD_SET(startup_pipes[i], fdset); 1159 1160 /* Wait in select until there is a connection. */ 1161 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1162 if (ret < 0 && errno != EINTR) 1163 error("select: %.100s", strerror(errno)); 1164 if (received_sigterm) { 1165 logit("Received signal %d; terminating.", 1166 (int) received_sigterm); 1167 close_listen_socks(); 1168 if (options.pid_file != NULL) 1169 unlink(options.pid_file); 1170 exit(received_sigterm == SIGTERM ? 0 : 255); 1171 } 1172 if (ret < 0) 1173 continue; 1174 1175 for (i = 0; i < options.max_startups; i++) 1176 if (startup_pipes[i] != -1 && 1177 FD_ISSET(startup_pipes[i], fdset)) { 1178 /* 1179 * the read end of the pipe is ready 1180 * if the child has closed the pipe 1181 * after successful authentication 1182 * or if the child has died 1183 */ 1184 close(startup_pipes[i]); 1185 startup_pipes[i] = -1; 1186 startups--; 1187 } 1188 for (i = 0; i < num_listen_socks; i++) { 1189 if (!FD_ISSET(listen_socks[i], fdset)) 1190 continue; 1191 fromlen = sizeof(from); 1192 *newsock = accept(listen_socks[i], 1193 (struct sockaddr *)&from, &fromlen); 1194 if (*newsock < 0) { 1195 if (errno != EINTR && errno != EWOULDBLOCK && 1196 errno != ECONNABORTED && errno != EAGAIN) 1197 error("accept: %.100s", 1198 strerror(errno)); 1199 if (errno == EMFILE || errno == ENFILE) 1200 usleep(100 * 1000); 1201 continue; 1202 } 1203 if (unset_nonblock(*newsock) == -1) { 1204 close(*newsock); 1205 continue; 1206 } 1207 if (drop_connection(startups) == 1) { 1208 char *laddr = get_local_ipaddr(*newsock); 1209 char *raddr = get_peer_ipaddr(*newsock); 1210 1211 verbose("drop connection #%d from [%s]:%d " 1212 "on [%s]:%d past MaxStartups", startups, 1213 raddr, get_peer_port(*newsock), 1214 laddr, get_local_port(*newsock)); 1215 free(laddr); 1216 free(raddr); 1217 close(*newsock); 1218 continue; 1219 } 1220 if (pipe(startup_p) == -1) { 1221 close(*newsock); 1222 continue; 1223 } 1224 1225 if (rexec_flag && socketpair(AF_UNIX, 1226 SOCK_STREAM, 0, config_s) == -1) { 1227 error("reexec socketpair: %s", 1228 strerror(errno)); 1229 close(*newsock); 1230 close(startup_p[0]); 1231 close(startup_p[1]); 1232 continue; 1233 } 1234 1235 for (j = 0; j < options.max_startups; j++) 1236 if (startup_pipes[j] == -1) { 1237 startup_pipes[j] = startup_p[0]; 1238 if (maxfd < startup_p[0]) 1239 maxfd = startup_p[0]; 1240 startups++; 1241 break; 1242 } 1243 1244 /* 1245 * Got connection. Fork a child to handle it, unless 1246 * we are in debugging mode. 1247 */ 1248 if (debug_flag) { 1249 /* 1250 * In debugging mode. Close the listening 1251 * socket, and start processing the 1252 * connection without forking. 1253 */ 1254 debug("Server will not fork when running in debugging mode."); 1255 close_listen_socks(); 1256 *sock_in = *newsock; 1257 *sock_out = *newsock; 1258 close(startup_p[0]); 1259 close(startup_p[1]); 1260 startup_pipe = -1; 1261 pid = getpid(); 1262 if (rexec_flag) { 1263 send_rexec_state(config_s[0], 1264 &cfg); 1265 close(config_s[0]); 1266 } 1267 break; 1268 } 1269 1270 /* 1271 * Normal production daemon. Fork, and have 1272 * the child process the connection. The 1273 * parent continues listening. 1274 */ 1275 platform_pre_fork(); 1276 if ((pid = fork()) == 0) { 1277 /* 1278 * Child. Close the listening and 1279 * max_startup sockets. Start using 1280 * the accepted socket. Reinitialize 1281 * logging (since our pid has changed). 1282 * We break out of the loop to handle 1283 * the connection. 1284 */ 1285 platform_post_fork_child(); 1286 startup_pipe = startup_p[1]; 1287 close_startup_pipes(); 1288 close_listen_socks(); 1289 *sock_in = *newsock; 1290 *sock_out = *newsock; 1291 log_init(__progname, 1292 options.log_level, 1293 options.log_facility, 1294 log_stderr); 1295 if (rexec_flag) 1296 close(config_s[0]); 1297 break; 1298 } 1299 1300 /* Parent. Stay in the loop. */ 1301 platform_post_fork_parent(pid); 1302 if (pid < 0) 1303 error("fork: %.100s", strerror(errno)); 1304 else 1305 debug("Forked child %ld.", (long)pid); 1306 1307 close(startup_p[1]); 1308 1309 if (rexec_flag) { 1310 send_rexec_state(config_s[0], &cfg); 1311 close(config_s[0]); 1312 close(config_s[1]); 1313 } 1314 close(*newsock); 1315 1316 /* 1317 * Ensure that our random state differs 1318 * from that of the child 1319 */ 1320 arc4random_stir(); 1321 arc4random_buf(rnd, sizeof(rnd)); 1322 #ifdef WITH_OPENSSL 1323 RAND_seed(rnd, sizeof(rnd)); 1324 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1325 fatal("%s: RAND_bytes failed", __func__); 1326 #endif 1327 explicit_bzero(rnd, sizeof(rnd)); 1328 } 1329 1330 /* child process check (or debug mode) */ 1331 if (num_listen_socks < 0) 1332 break; 1333 } 1334 } 1335 1336 /* 1337 * If IP options are supported, make sure there are none (log and 1338 * return an error if any are found). Basically we are worried about 1339 * source routing; it can be used to pretend you are somebody 1340 * (ip-address) you are not. That itself may be "almost acceptable" 1341 * under certain circumstances, but rhosts autentication is useless 1342 * if source routing is accepted. Notice also that if we just dropped 1343 * source routing here, the other side could use IP spoofing to do 1344 * rest of the interaction and could still bypass security. So we 1345 * exit here if we detect any IP options. 1346 */ 1347 static void 1348 check_ip_options(struct ssh *ssh) 1349 { 1350 #ifdef IP_OPTIONS 1351 int sock_in = ssh_packet_get_connection_in(ssh); 1352 struct sockaddr_storage from; 1353 u_char opts[200]; 1354 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1355 char text[sizeof(opts) * 3 + 1]; 1356 1357 memset(&from, 0, sizeof(from)); 1358 if (getpeername(sock_in, (struct sockaddr *)&from, 1359 &fromlen) < 0) 1360 return; 1361 if (from.ss_family != AF_INET) 1362 return; 1363 /* XXX IPv6 options? */ 1364 1365 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1366 &option_size) >= 0 && option_size != 0) { 1367 text[0] = '\0'; 1368 for (i = 0; i < option_size; i++) 1369 snprintf(text + i*3, sizeof(text) - i*3, 1370 " %2.2x", opts[i]); 1371 fatal("Connection from %.100s port %d with IP opts: %.800s", 1372 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1373 } 1374 return; 1375 #endif /* IP_OPTIONS */ 1376 } 1377 1378 /* 1379 * Main program for the daemon. 1380 */ 1381 int 1382 main(int ac, char **av) 1383 { 1384 struct ssh *ssh = NULL; 1385 extern char *optarg; 1386 extern int optind; 1387 int r, opt, i, j, on = 1, already_daemon; 1388 int sock_in = -1, sock_out = -1, newsock = -1; 1389 const char *remote_ip; 1390 int remote_port; 1391 char *fp, *line, *laddr, *logfile = NULL; 1392 int config_s[2] = { -1 , -1 }; 1393 u_int n; 1394 u_int64_t ibytes, obytes; 1395 mode_t new_umask; 1396 Key *key; 1397 Key *pubkey; 1398 int keytype; 1399 Authctxt *authctxt; 1400 struct connection_info *connection_info = get_connection_info(0, 0); 1401 1402 ssh_malloc_init(); /* must be called before any mallocs */ 1403 1404 #ifdef HAVE_SECUREWARE 1405 (void)set_auth_parameters(ac, av); 1406 #endif 1407 __progname = ssh_get_progname(av[0]); 1408 1409 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1410 saved_argc = ac; 1411 rexec_argc = ac; 1412 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1413 for (i = 0; i < ac; i++) 1414 saved_argv[i] = xstrdup(av[i]); 1415 saved_argv[i] = NULL; 1416 1417 #ifndef HAVE_SETPROCTITLE 1418 /* Prepare for later setproctitle emulation */ 1419 compat_init_setproctitle(ac, av); 1420 av = saved_argv; 1421 #endif 1422 1423 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1424 debug("setgroups(): %.200s", strerror(errno)); 1425 1426 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1427 sanitise_stdfd(); 1428 1429 /* Initialize configuration options to their default values. */ 1430 initialize_server_options(&options); 1431 1432 /* Parse command-line arguments. */ 1433 while ((opt = getopt(ac, av, 1434 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1435 switch (opt) { 1436 case '4': 1437 options.address_family = AF_INET; 1438 break; 1439 case '6': 1440 options.address_family = AF_INET6; 1441 break; 1442 case 'f': 1443 config_file_name = optarg; 1444 break; 1445 case 'c': 1446 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1447 fprintf(stderr, "too many host certificates.\n"); 1448 exit(1); 1449 } 1450 options.host_cert_files[options.num_host_cert_files++] = 1451 derelativise_path(optarg); 1452 break; 1453 case 'd': 1454 if (debug_flag == 0) { 1455 debug_flag = 1; 1456 options.log_level = SYSLOG_LEVEL_DEBUG1; 1457 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1458 options.log_level++; 1459 break; 1460 case 'D': 1461 no_daemon_flag = 1; 1462 break; 1463 case 'E': 1464 logfile = optarg; 1465 /* FALLTHROUGH */ 1466 case 'e': 1467 log_stderr = 1; 1468 break; 1469 case 'i': 1470 inetd_flag = 1; 1471 break; 1472 case 'r': 1473 rexec_flag = 0; 1474 break; 1475 case 'R': 1476 rexeced_flag = 1; 1477 inetd_flag = 1; 1478 break; 1479 case 'Q': 1480 /* ignored */ 1481 break; 1482 case 'q': 1483 options.log_level = SYSLOG_LEVEL_QUIET; 1484 break; 1485 case 'b': 1486 /* protocol 1, ignored */ 1487 break; 1488 case 'p': 1489 options.ports_from_cmdline = 1; 1490 if (options.num_ports >= MAX_PORTS) { 1491 fprintf(stderr, "too many ports.\n"); 1492 exit(1); 1493 } 1494 options.ports[options.num_ports++] = a2port(optarg); 1495 if (options.ports[options.num_ports-1] <= 0) { 1496 fprintf(stderr, "Bad port number.\n"); 1497 exit(1); 1498 } 1499 break; 1500 case 'g': 1501 if ((options.login_grace_time = convtime(optarg)) == -1) { 1502 fprintf(stderr, "Invalid login grace time.\n"); 1503 exit(1); 1504 } 1505 break; 1506 case 'k': 1507 /* protocol 1, ignored */ 1508 break; 1509 case 'h': 1510 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1511 fprintf(stderr, "too many host keys.\n"); 1512 exit(1); 1513 } 1514 options.host_key_files[options.num_host_key_files++] = 1515 derelativise_path(optarg); 1516 break; 1517 case 't': 1518 test_flag = 1; 1519 break; 1520 case 'T': 1521 test_flag = 2; 1522 break; 1523 case 'C': 1524 if (parse_server_match_testspec(connection_info, 1525 optarg) == -1) 1526 exit(1); 1527 break; 1528 case 'u': 1529 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1530 if (utmp_len > HOST_NAME_MAX+1) { 1531 fprintf(stderr, "Invalid utmp length.\n"); 1532 exit(1); 1533 } 1534 break; 1535 case 'o': 1536 line = xstrdup(optarg); 1537 if (process_server_config_line(&options, line, 1538 "command-line", 0, NULL, NULL) != 0) 1539 exit(1); 1540 free(line); 1541 break; 1542 case '?': 1543 default: 1544 usage(); 1545 break; 1546 } 1547 } 1548 if (rexeced_flag || inetd_flag) 1549 rexec_flag = 0; 1550 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1551 fatal("sshd re-exec requires execution with an absolute path"); 1552 if (rexeced_flag) 1553 closefrom(REEXEC_MIN_FREE_FD); 1554 else 1555 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1556 1557 #ifdef WITH_OPENSSL 1558 OpenSSL_add_all_algorithms(); 1559 #endif 1560 1561 /* If requested, redirect the logs to the specified logfile. */ 1562 if (logfile != NULL) 1563 log_redirect_stderr_to(logfile); 1564 /* 1565 * Force logging to stderr until we have loaded the private host 1566 * key (unless started from inetd) 1567 */ 1568 log_init(__progname, 1569 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1570 SYSLOG_LEVEL_INFO : options.log_level, 1571 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1572 SYSLOG_FACILITY_AUTH : options.log_facility, 1573 log_stderr || !inetd_flag); 1574 1575 /* 1576 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1577 * root's environment 1578 */ 1579 if (getenv("KRB5CCNAME") != NULL) 1580 (void) unsetenv("KRB5CCNAME"); 1581 1582 #ifdef _UNICOS 1583 /* Cray can define user privs drop all privs now! 1584 * Not needed on PRIV_SU systems! 1585 */ 1586 drop_cray_privs(); 1587 #endif 1588 1589 sensitive_data.have_ssh2_key = 0; 1590 1591 /* 1592 * If we're doing an extended config test, make sure we have all of 1593 * the parameters we need. If we're not doing an extended test, 1594 * do not silently ignore connection test params. 1595 */ 1596 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1597 fatal("user, host and addr are all required when testing " 1598 "Match configs"); 1599 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1600 fatal("Config test connection parameter (-C) provided without " 1601 "test mode (-T)"); 1602 1603 /* Fetch our configuration */ 1604 buffer_init(&cfg); 1605 if (rexeced_flag) 1606 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1607 else if (strcasecmp(config_file_name, "none") != 0) 1608 load_server_config(config_file_name, &cfg); 1609 1610 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1611 &cfg, NULL); 1612 1613 seed_rng(); 1614 1615 /* Fill in default values for those options not explicitly set. */ 1616 fill_default_server_options(&options); 1617 1618 /* challenge-response is implemented via keyboard interactive */ 1619 if (options.challenge_response_authentication) 1620 options.kbd_interactive_authentication = 1; 1621 1622 /* Check that options are sensible */ 1623 if (options.authorized_keys_command_user == NULL && 1624 (options.authorized_keys_command != NULL && 1625 strcasecmp(options.authorized_keys_command, "none") != 0)) 1626 fatal("AuthorizedKeysCommand set without " 1627 "AuthorizedKeysCommandUser"); 1628 if (options.authorized_principals_command_user == NULL && 1629 (options.authorized_principals_command != NULL && 1630 strcasecmp(options.authorized_principals_command, "none") != 0)) 1631 fatal("AuthorizedPrincipalsCommand set without " 1632 "AuthorizedPrincipalsCommandUser"); 1633 1634 /* 1635 * Check whether there is any path through configured auth methods. 1636 * Unfortunately it is not possible to verify this generally before 1637 * daemonisation in the presence of Match block, but this catches 1638 * and warns for trivial misconfigurations that could break login. 1639 */ 1640 if (options.num_auth_methods != 0) { 1641 for (n = 0; n < options.num_auth_methods; n++) { 1642 if (auth2_methods_valid(options.auth_methods[n], 1643 1) == 0) 1644 break; 1645 } 1646 if (n >= options.num_auth_methods) 1647 fatal("AuthenticationMethods cannot be satisfied by " 1648 "enabled authentication methods"); 1649 } 1650 1651 /* set default channel AF */ 1652 channel_set_af(options.address_family); 1653 1654 /* Check that there are no remaining arguments. */ 1655 if (optind < ac) { 1656 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1657 exit(1); 1658 } 1659 1660 debug("sshd version %s, %s", SSH_VERSION, 1661 #ifdef WITH_OPENSSL 1662 SSLeay_version(SSLEAY_VERSION) 1663 #else 1664 "without OpenSSL" 1665 #endif 1666 ); 1667 1668 /* Store privilege separation user for later use if required. */ 1669 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1670 if (use_privsep || options.kerberos_authentication) 1671 fatal("Privilege separation user %s does not exist", 1672 SSH_PRIVSEP_USER); 1673 } else { 1674 explicit_bzero(privsep_pw->pw_passwd, 1675 strlen(privsep_pw->pw_passwd)); 1676 privsep_pw = pwcopy(privsep_pw); 1677 free(privsep_pw->pw_passwd); 1678 privsep_pw->pw_passwd = xstrdup("*"); 1679 } 1680 endpwent(); 1681 1682 /* load host keys */ 1683 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1684 sizeof(Key *)); 1685 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1686 sizeof(Key *)); 1687 1688 if (options.host_key_agent) { 1689 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1690 setenv(SSH_AUTHSOCKET_ENV_NAME, 1691 options.host_key_agent, 1); 1692 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1693 have_agent = 1; 1694 else 1695 error("Could not connect to agent \"%s\": %s", 1696 options.host_key_agent, ssh_err(r)); 1697 } 1698 1699 for (i = 0; i < options.num_host_key_files; i++) { 1700 if (options.host_key_files[i] == NULL) 1701 continue; 1702 key = key_load_private(options.host_key_files[i], "", NULL); 1703 pubkey = key_load_public(options.host_key_files[i], NULL); 1704 1705 if ((pubkey != NULL && pubkey->type == KEY_RSA1) || 1706 (key != NULL && key->type == KEY_RSA1)) { 1707 verbose("Ignoring RSA1 key %s", 1708 options.host_key_files[i]); 1709 key_free(key); 1710 key_free(pubkey); 1711 continue; 1712 } 1713 if (pubkey == NULL && key != NULL) 1714 pubkey = key_demote(key); 1715 sensitive_data.host_keys[i] = key; 1716 sensitive_data.host_pubkeys[i] = pubkey; 1717 1718 if (key == NULL && pubkey != NULL && have_agent) { 1719 debug("will rely on agent for hostkey %s", 1720 options.host_key_files[i]); 1721 keytype = pubkey->type; 1722 } else if (key != NULL) { 1723 keytype = key->type; 1724 } else { 1725 error("Could not load host key: %s", 1726 options.host_key_files[i]); 1727 sensitive_data.host_keys[i] = NULL; 1728 sensitive_data.host_pubkeys[i] = NULL; 1729 continue; 1730 } 1731 1732 switch (keytype) { 1733 case KEY_RSA: 1734 case KEY_DSA: 1735 case KEY_ECDSA: 1736 case KEY_ED25519: 1737 if (have_agent || key != NULL) 1738 sensitive_data.have_ssh2_key = 1; 1739 break; 1740 } 1741 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1742 SSH_FP_DEFAULT)) == NULL) 1743 fatal("sshkey_fingerprint failed"); 1744 debug("%s host key #%d: %s %s", 1745 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1746 free(fp); 1747 } 1748 if (!sensitive_data.have_ssh2_key) { 1749 logit("sshd: no hostkeys available -- exiting."); 1750 exit(1); 1751 } 1752 1753 /* 1754 * Load certificates. They are stored in an array at identical 1755 * indices to the public keys that they relate to. 1756 */ 1757 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1758 sizeof(Key *)); 1759 for (i = 0; i < options.num_host_key_files; i++) 1760 sensitive_data.host_certificates[i] = NULL; 1761 1762 for (i = 0; i < options.num_host_cert_files; i++) { 1763 if (options.host_cert_files[i] == NULL) 1764 continue; 1765 key = key_load_public(options.host_cert_files[i], NULL); 1766 if (key == NULL) { 1767 error("Could not load host certificate: %s", 1768 options.host_cert_files[i]); 1769 continue; 1770 } 1771 if (!key_is_cert(key)) { 1772 error("Certificate file is not a certificate: %s", 1773 options.host_cert_files[i]); 1774 key_free(key); 1775 continue; 1776 } 1777 /* Find matching private key */ 1778 for (j = 0; j < options.num_host_key_files; j++) { 1779 if (key_equal_public(key, 1780 sensitive_data.host_keys[j])) { 1781 sensitive_data.host_certificates[j] = key; 1782 break; 1783 } 1784 } 1785 if (j >= options.num_host_key_files) { 1786 error("No matching private key for certificate: %s", 1787 options.host_cert_files[i]); 1788 key_free(key); 1789 continue; 1790 } 1791 sensitive_data.host_certificates[j] = key; 1792 debug("host certificate: #%d type %d %s", j, key->type, 1793 key_type(key)); 1794 } 1795 1796 if (use_privsep) { 1797 struct stat st; 1798 1799 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1800 (S_ISDIR(st.st_mode) == 0)) 1801 fatal("Missing privilege separation directory: %s", 1802 _PATH_PRIVSEP_CHROOT_DIR); 1803 1804 #ifdef HAVE_CYGWIN 1805 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1806 (st.st_uid != getuid () || 1807 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1808 #else 1809 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1810 #endif 1811 fatal("%s must be owned by root and not group or " 1812 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1813 } 1814 1815 if (test_flag > 1) { 1816 if (server_match_spec_complete(connection_info) == 1) 1817 parse_server_match_config(&options, connection_info); 1818 dump_config(&options); 1819 } 1820 1821 /* Configuration looks good, so exit if in test mode. */ 1822 if (test_flag) 1823 exit(0); 1824 1825 /* 1826 * Clear out any supplemental groups we may have inherited. This 1827 * prevents inadvertent creation of files with bad modes (in the 1828 * portable version at least, it's certainly possible for PAM 1829 * to create a file, and we can't control the code in every 1830 * module which might be used). 1831 */ 1832 if (setgroups(0, NULL) < 0) 1833 debug("setgroups() failed: %.200s", strerror(errno)); 1834 1835 if (rexec_flag) { 1836 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1837 for (i = 0; i < rexec_argc; i++) { 1838 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1839 rexec_argv[i] = saved_argv[i]; 1840 } 1841 rexec_argv[rexec_argc] = "-R"; 1842 rexec_argv[rexec_argc + 1] = NULL; 1843 } 1844 1845 /* Ensure that umask disallows at least group and world write */ 1846 new_umask = umask(0077) | 0022; 1847 (void) umask(new_umask); 1848 1849 /* Initialize the log (it is reinitialized below in case we forked). */ 1850 if (debug_flag && (!inetd_flag || rexeced_flag)) 1851 log_stderr = 1; 1852 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1853 1854 /* 1855 * If not in debugging mode, not started from inetd and not already 1856 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1857 * terminal, and fork. The original process exits. 1858 */ 1859 already_daemon = daemonized(); 1860 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1861 1862 if (daemon(0, 0) < 0) 1863 fatal("daemon() failed: %.200s", strerror(errno)); 1864 1865 disconnect_controlling_tty(); 1866 } 1867 /* Reinitialize the log (because of the fork above). */ 1868 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1869 1870 /* Avoid killing the process in high-pressure swapping environments. */ 1871 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1872 debug("madvise(): %.200s", strerror(errno)); 1873 1874 /* Chdir to the root directory so that the current disk can be 1875 unmounted if desired. */ 1876 if (chdir("/") == -1) 1877 error("chdir(\"/\"): %s", strerror(errno)); 1878 1879 /* ignore SIGPIPE */ 1880 signal(SIGPIPE, SIG_IGN); 1881 1882 /* Get a connection, either from inetd or a listening TCP socket */ 1883 if (inetd_flag) { 1884 server_accept_inetd(&sock_in, &sock_out); 1885 } else { 1886 platform_pre_listen(); 1887 server_listen(); 1888 1889 signal(SIGHUP, sighup_handler); 1890 signal(SIGCHLD, main_sigchld_handler); 1891 signal(SIGTERM, sigterm_handler); 1892 signal(SIGQUIT, sigterm_handler); 1893 1894 /* 1895 * Write out the pid file after the sigterm handler 1896 * is setup and the listen sockets are bound 1897 */ 1898 if (options.pid_file != NULL && !debug_flag) { 1899 FILE *f = fopen(options.pid_file, "w"); 1900 1901 if (f == NULL) { 1902 error("Couldn't create pid file \"%s\": %s", 1903 options.pid_file, strerror(errno)); 1904 } else { 1905 fprintf(f, "%ld\n", (long) getpid()); 1906 fclose(f); 1907 } 1908 } 1909 1910 /* Accept a connection and return in a forked child */ 1911 server_accept_loop(&sock_in, &sock_out, 1912 &newsock, config_s); 1913 } 1914 1915 /* This is the child processing a new connection. */ 1916 setproctitle("%s", "[accepted]"); 1917 1918 /* 1919 * Create a new session and process group since the 4.4BSD 1920 * setlogin() affects the entire process group. We don't 1921 * want the child to be able to affect the parent. 1922 */ 1923 #if !defined(SSHD_ACQUIRES_CTTY) 1924 /* 1925 * If setsid is called, on some platforms sshd will later acquire a 1926 * controlling terminal which will result in "could not set 1927 * controlling tty" errors. 1928 */ 1929 if (!debug_flag && !inetd_flag && setsid() < 0) 1930 error("setsid: %.100s", strerror(errno)); 1931 #endif 1932 1933 if (rexec_flag) { 1934 int fd; 1935 1936 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1937 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1938 dup2(newsock, STDIN_FILENO); 1939 dup2(STDIN_FILENO, STDOUT_FILENO); 1940 if (startup_pipe == -1) 1941 close(REEXEC_STARTUP_PIPE_FD); 1942 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1943 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1944 close(startup_pipe); 1945 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1946 } 1947 1948 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1949 close(config_s[1]); 1950 1951 execv(rexec_argv[0], rexec_argv); 1952 1953 /* Reexec has failed, fall back and continue */ 1954 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1955 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1956 log_init(__progname, options.log_level, 1957 options.log_facility, log_stderr); 1958 1959 /* Clean up fds */ 1960 close(REEXEC_CONFIG_PASS_FD); 1961 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1962 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1963 dup2(fd, STDIN_FILENO); 1964 dup2(fd, STDOUT_FILENO); 1965 if (fd > STDERR_FILENO) 1966 close(fd); 1967 } 1968 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1969 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1970 } 1971 1972 /* Executed child processes don't need these. */ 1973 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1974 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1975 1976 /* 1977 * Disable the key regeneration alarm. We will not regenerate the 1978 * key since we are no longer in a position to give it to anyone. We 1979 * will not restart on SIGHUP since it no longer makes sense. 1980 */ 1981 alarm(0); 1982 signal(SIGALRM, SIG_DFL); 1983 signal(SIGHUP, SIG_DFL); 1984 signal(SIGTERM, SIG_DFL); 1985 signal(SIGQUIT, SIG_DFL); 1986 signal(SIGCHLD, SIG_DFL); 1987 signal(SIGINT, SIG_DFL); 1988 1989 #ifdef __FreeBSD__ 1990 /* 1991 * Initialize the resolver. This may not happen automatically 1992 * before privsep chroot(). 1993 */ 1994 if ((_res.options & RES_INIT) == 0) { 1995 debug("res_init()"); 1996 res_init(); 1997 } 1998 #ifdef GSSAPI 1999 /* 2000 * Force GSS-API to parse its configuration and load any 2001 * mechanism plugins. 2002 */ 2003 { 2004 gss_OID_set mechs; 2005 OM_uint32 minor_status; 2006 gss_indicate_mechs(&minor_status, &mechs); 2007 gss_release_oid_set(&minor_status, &mechs); 2008 } 2009 #endif 2010 #endif 2011 2012 /* 2013 * Register our connection. This turns encryption off because we do 2014 * not have a key. 2015 */ 2016 packet_set_connection(sock_in, sock_out); 2017 packet_set_server(); 2018 ssh = active_state; /* XXX */ 2019 check_ip_options(ssh); 2020 2021 /* Set SO_KEEPALIVE if requested. */ 2022 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2023 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2024 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2025 2026 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2027 debug("ssh_remote_port failed"); 2028 cleanup_exit(255); 2029 } 2030 2031 /* 2032 * The rest of the code depends on the fact that 2033 * ssh_remote_ipaddr() caches the remote ip, even if 2034 * the socket goes away. 2035 */ 2036 remote_ip = ssh_remote_ipaddr(ssh); 2037 2038 #ifdef SSH_AUDIT_EVENTS 2039 audit_connection_from(remote_ip, remote_port); 2040 #endif 2041 #ifdef LIBWRAP 2042 allow_severity = options.log_facility|LOG_INFO; 2043 deny_severity = options.log_facility|LOG_WARNING; 2044 /* Check whether logins are denied from this host. */ 2045 if (packet_connection_is_on_socket()) { 2046 struct request_info req; 2047 2048 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2049 fromhost(&req); 2050 2051 if (!hosts_access(&req)) { 2052 debug("Connection refused by tcp wrapper"); 2053 refuse(&req); 2054 /* NOTREACHED */ 2055 fatal("libwrap refuse returns"); 2056 } 2057 } 2058 #endif /* LIBWRAP */ 2059 2060 /* Log the connection. */ 2061 laddr = get_local_ipaddr(sock_in); 2062 verbose("Connection from %s port %d on %s port %d", 2063 remote_ip, remote_port, laddr, ssh_local_port(ssh)); 2064 free(laddr); 2065 2066 /* 2067 * We don't want to listen forever unless the other side 2068 * successfully authenticates itself. So we set up an alarm which is 2069 * cleared after successful authentication. A limit of zero 2070 * indicates no limit. Note that we don't set the alarm in debugging 2071 * mode; it is just annoying to have the server exit just when you 2072 * are about to discover the bug. 2073 */ 2074 signal(SIGALRM, grace_alarm_handler); 2075 if (!debug_flag) 2076 alarm(options.login_grace_time); 2077 2078 sshd_exchange_identification(ssh, sock_in, sock_out); 2079 packet_set_nonblocking(); 2080 2081 /* allocate authentication context */ 2082 authctxt = xcalloc(1, sizeof(*authctxt)); 2083 2084 authctxt->loginmsg = &loginmsg; 2085 2086 /* XXX global for cleanup, access from other modules */ 2087 the_authctxt = authctxt; 2088 2089 /* prepare buffer to collect messages to display to user after login */ 2090 buffer_init(&loginmsg); 2091 auth_debug_reset(); 2092 2093 BLACKLIST_INIT(); 2094 2095 if (use_privsep) { 2096 if (privsep_preauth(authctxt) == 1) 2097 goto authenticated; 2098 } else if (have_agent) { 2099 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2100 error("Unable to get agent socket: %s", ssh_err(r)); 2101 have_agent = 0; 2102 } 2103 } 2104 2105 /* perform the key exchange */ 2106 /* authenticate user and start session */ 2107 do_ssh2_kex(); 2108 do_authentication2(authctxt); 2109 2110 /* 2111 * If we use privilege separation, the unprivileged child transfers 2112 * the current keystate and exits 2113 */ 2114 if (use_privsep) { 2115 mm_send_keystate(pmonitor); 2116 exit(0); 2117 } 2118 2119 authenticated: 2120 /* 2121 * Cancel the alarm we set to limit the time taken for 2122 * authentication. 2123 */ 2124 alarm(0); 2125 signal(SIGALRM, SIG_DFL); 2126 authctxt->authenticated = 1; 2127 if (startup_pipe != -1) { 2128 close(startup_pipe); 2129 startup_pipe = -1; 2130 } 2131 2132 #ifdef SSH_AUDIT_EVENTS 2133 audit_event(SSH_AUTH_SUCCESS); 2134 #endif 2135 2136 #ifdef GSSAPI 2137 if (options.gss_authentication) { 2138 temporarily_use_uid(authctxt->pw); 2139 ssh_gssapi_storecreds(); 2140 restore_uid(); 2141 } 2142 #endif 2143 #ifdef USE_PAM 2144 if (options.use_pam) { 2145 do_pam_setcred(1); 2146 do_pam_session(); 2147 } 2148 #endif 2149 2150 /* 2151 * In privilege separation, we fork another child and prepare 2152 * file descriptor passing. 2153 */ 2154 if (use_privsep) { 2155 privsep_postauth(authctxt); 2156 /* the monitor process [priv] will not return */ 2157 } 2158 2159 packet_set_timeout(options.client_alive_interval, 2160 options.client_alive_count_max); 2161 2162 /* Try to send all our hostkeys to the client */ 2163 notify_hostkeys(active_state); 2164 2165 /* Start session. */ 2166 do_authenticated(authctxt); 2167 2168 /* The connection has been terminated. */ 2169 packet_get_bytes(&ibytes, &obytes); 2170 verbose("Transferred: sent %llu, received %llu bytes", 2171 (unsigned long long)obytes, (unsigned long long)ibytes); 2172 2173 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2174 2175 #ifdef USE_PAM 2176 if (options.use_pam) 2177 finish_pam(); 2178 #endif /* USE_PAM */ 2179 2180 #ifdef SSH_AUDIT_EVENTS 2181 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2182 #endif 2183 2184 packet_close(); 2185 2186 if (use_privsep) 2187 mm_terminate(); 2188 2189 exit(0); 2190 } 2191 2192 int 2193 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, size_t *slen, 2194 const u_char *data, size_t dlen, const char *alg, u_int flag) 2195 { 2196 int r; 2197 u_int xxx_slen, xxx_dlen = dlen; 2198 2199 if (privkey) { 2200 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen, 2201 alg) < 0)) 2202 fatal("%s: key_sign failed", __func__); 2203 if (slen) 2204 *slen = xxx_slen; 2205 } else if (use_privsep) { 2206 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen, 2207 alg) < 0) 2208 fatal("%s: pubkey_sign failed", __func__); 2209 if (slen) 2210 *slen = xxx_slen; 2211 } else { 2212 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2213 data, dlen, alg, datafellows)) != 0) 2214 fatal("%s: ssh_agent_sign failed: %s", 2215 __func__, ssh_err(r)); 2216 } 2217 return 0; 2218 } 2219 2220 /* SSH2 key exchange */ 2221 static void 2222 do_ssh2_kex(void) 2223 { 2224 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2225 struct kex *kex; 2226 int r; 2227 2228 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2229 options.kex_algorithms); 2230 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2231 options.ciphers); 2232 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2233 options.ciphers); 2234 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2235 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2236 2237 if (options.compression == COMP_NONE) { 2238 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2239 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2240 } 2241 2242 if (options.rekey_limit || options.rekey_interval) 2243 packet_set_rekey_limits(options.rekey_limit, 2244 options.rekey_interval); 2245 2246 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2247 list_hostkey_types()); 2248 2249 /* start key exchange */ 2250 if ((r = kex_setup(active_state, myproposal)) != 0) 2251 fatal("kex_setup: %s", ssh_err(r)); 2252 kex = active_state->kex; 2253 #ifdef WITH_OPENSSL 2254 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2255 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2256 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2257 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2258 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2259 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2260 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2261 # ifdef OPENSSL_HAS_ECC 2262 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2263 # endif 2264 #endif 2265 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2266 kex->server = 1; 2267 kex->client_version_string=client_version_string; 2268 kex->server_version_string=server_version_string; 2269 kex->load_host_public_key=&get_hostkey_public_by_type; 2270 kex->load_host_private_key=&get_hostkey_private_by_type; 2271 kex->host_key_index=&get_hostkey_index; 2272 kex->sign = sshd_hostkey_sign; 2273 2274 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 2275 2276 session_id2 = kex->session_id; 2277 session_id2_len = kex->session_id_len; 2278 2279 #ifdef DEBUG_KEXDH 2280 /* send 1st encrypted/maced/compressed message */ 2281 packet_start(SSH2_MSG_IGNORE); 2282 packet_put_cstring("markus"); 2283 packet_send(); 2284 packet_write_wait(); 2285 #endif 2286 debug("KEX done"); 2287 } 2288 2289 /* server specific fatal cleanup */ 2290 void 2291 cleanup_exit(int i) 2292 { 2293 if (the_authctxt) { 2294 do_cleanup(the_authctxt); 2295 if (use_privsep && privsep_is_preauth && 2296 pmonitor != NULL && pmonitor->m_pid > 1) { 2297 debug("Killing privsep child %d", pmonitor->m_pid); 2298 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2299 errno != ESRCH) 2300 error("%s: kill(%d): %s", __func__, 2301 pmonitor->m_pid, strerror(errno)); 2302 } 2303 } 2304 #ifdef SSH_AUDIT_EVENTS 2305 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2306 if (!use_privsep || mm_is_monitor()) 2307 audit_event(SSH_CONNECTION_ABANDON); 2308 #endif 2309 _exit(i); 2310 } 2311