1 /* $OpenBSD: sshd.c,v 1.485 2017/03/15 03:52:30 deraadt Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 47 #include <sys/types.h> 48 #include <sys/ioctl.h> 49 #include <sys/socket.h> 50 #ifdef HAVE_SYS_STAT_H 51 # include <sys/stat.h> 52 #endif 53 #ifdef HAVE_SYS_TIME_H 54 # include <sys/time.h> 55 #endif 56 #include "openbsd-compat/sys-tree.h" 57 #include "openbsd-compat/sys-queue.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 #include <limits.h> 75 76 #ifdef WITH_OPENSSL 77 #include <openssl/dh.h> 78 #include <openssl/bn.h> 79 #include <openssl/rand.h> 80 #include "openbsd-compat/openssl-compat.h" 81 #endif 82 83 #ifdef HAVE_SECUREWARE 84 #include <sys/security.h> 85 #include <prot.h> 86 #endif 87 88 #include "xmalloc.h" 89 #include "ssh.h" 90 #include "ssh2.h" 91 #include "rsa.h" 92 #include "sshpty.h" 93 #include "packet.h" 94 #include "log.h" 95 #include "buffer.h" 96 #include "misc.h" 97 #include "match.h" 98 #include "servconf.h" 99 #include "uidswap.h" 100 #include "compat.h" 101 #include "cipher.h" 102 #include "digest.h" 103 #include "key.h" 104 #include "kex.h" 105 #include "myproposal.h" 106 #include "authfile.h" 107 #include "pathnames.h" 108 #include "atomicio.h" 109 #include "canohost.h" 110 #include "hostfile.h" 111 #include "auth.h" 112 #include "authfd.h" 113 #include "msg.h" 114 #include "dispatch.h" 115 #include "channels.h" 116 #include "session.h" 117 #include "monitor.h" 118 #ifdef GSSAPI 119 #include "ssh-gss.h" 120 #endif 121 #include "monitor_wrap.h" 122 #include "ssh-sandbox.h" 123 #include "version.h" 124 #include "ssherr.h" 125 126 /* Re-exec fds */ 127 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 128 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 129 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 130 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 131 132 extern char *__progname; 133 134 /* Server configuration options. */ 135 ServerOptions options; 136 137 /* Name of the server configuration file. */ 138 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 139 140 /* 141 * Debug mode flag. This can be set on the command line. If debug 142 * mode is enabled, extra debugging output will be sent to the system 143 * log, the daemon will not go to background, and will exit after processing 144 * the first connection. 145 */ 146 int debug_flag = 0; 147 148 /* Flag indicating that the daemon should only test the configuration and keys. */ 149 int test_flag = 0; 150 151 /* Flag indicating that the daemon is being started from inetd. */ 152 int inetd_flag = 0; 153 154 /* Flag indicating that sshd should not detach and become a daemon. */ 155 int no_daemon_flag = 0; 156 157 /* debug goes to stderr unless inetd_flag is set */ 158 int log_stderr = 0; 159 160 /* Saved arguments to main(). */ 161 char **saved_argv; 162 int saved_argc; 163 164 /* re-exec */ 165 int rexeced_flag = 0; 166 int rexec_flag = 1; 167 int rexec_argc = 0; 168 char **rexec_argv; 169 170 /* 171 * The sockets that the server is listening; this is used in the SIGHUP 172 * signal handler. 173 */ 174 #define MAX_LISTEN_SOCKS 16 175 int listen_socks[MAX_LISTEN_SOCKS]; 176 int num_listen_socks = 0; 177 178 /* 179 * the client's version string, passed by sshd2 in compat mode. if != NULL, 180 * sshd will skip the version-number exchange 181 */ 182 char *client_version_string = NULL; 183 char *server_version_string = NULL; 184 185 /* Daemon's agent connection */ 186 int auth_sock = -1; 187 int have_agent = 0; 188 189 /* 190 * Any really sensitive data in the application is contained in this 191 * structure. The idea is that this structure could be locked into memory so 192 * that the pages do not get written into swap. However, there are some 193 * problems. The private key contains BIGNUMs, and we do not (in principle) 194 * have access to the internals of them, and locking just the structure is 195 * not very useful. Currently, memory locking is not implemented. 196 */ 197 struct { 198 Key **host_keys; /* all private host keys */ 199 Key **host_pubkeys; /* all public host keys */ 200 Key **host_certificates; /* all public host certificates */ 201 int have_ssh2_key; 202 } sensitive_data; 203 204 /* This is set to true when a signal is received. */ 205 static volatile sig_atomic_t received_sighup = 0; 206 static volatile sig_atomic_t received_sigterm = 0; 207 208 /* session identifier, used by RSA-auth */ 209 u_char session_id[16]; 210 211 /* same for ssh2 */ 212 u_char *session_id2 = NULL; 213 u_int session_id2_len = 0; 214 215 /* record remote hostname or ip */ 216 u_int utmp_len = HOST_NAME_MAX+1; 217 218 /* options.max_startup sized array of fd ints */ 219 int *startup_pipes = NULL; 220 int startup_pipe; /* in child */ 221 222 /* variables used for privilege separation */ 223 int use_privsep = -1; 224 struct monitor *pmonitor = NULL; 225 int privsep_is_preauth = 1; 226 227 /* global authentication context */ 228 Authctxt *the_authctxt = NULL; 229 230 /* sshd_config buffer */ 231 Buffer cfg; 232 233 /* message to be displayed after login */ 234 Buffer loginmsg; 235 236 /* Unprivileged user */ 237 struct passwd *privsep_pw = NULL; 238 239 /* Prototypes for various functions defined later in this file. */ 240 void destroy_sensitive_data(void); 241 void demote_sensitive_data(void); 242 static void do_ssh2_kex(void); 243 244 /* 245 * Close all listening sockets 246 */ 247 static void 248 close_listen_socks(void) 249 { 250 int i; 251 252 for (i = 0; i < num_listen_socks; i++) 253 close(listen_socks[i]); 254 num_listen_socks = -1; 255 } 256 257 static void 258 close_startup_pipes(void) 259 { 260 int i; 261 262 if (startup_pipes) 263 for (i = 0; i < options.max_startups; i++) 264 if (startup_pipes[i] != -1) 265 close(startup_pipes[i]); 266 } 267 268 /* 269 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 270 * the effect is to reread the configuration file (and to regenerate 271 * the server key). 272 */ 273 274 /*ARGSUSED*/ 275 static void 276 sighup_handler(int sig) 277 { 278 int save_errno = errno; 279 280 received_sighup = 1; 281 signal(SIGHUP, sighup_handler); 282 errno = save_errno; 283 } 284 285 /* 286 * Called from the main program after receiving SIGHUP. 287 * Restarts the server. 288 */ 289 static void 290 sighup_restart(void) 291 { 292 logit("Received SIGHUP; restarting."); 293 if (options.pid_file != NULL) 294 unlink(options.pid_file); 295 platform_pre_restart(); 296 close_listen_socks(); 297 close_startup_pipes(); 298 alarm(0); /* alarm timer persists across exec */ 299 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 300 execv(saved_argv[0], saved_argv); 301 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 302 strerror(errno)); 303 exit(1); 304 } 305 306 /* 307 * Generic signal handler for terminating signals in the master daemon. 308 */ 309 /*ARGSUSED*/ 310 static void 311 sigterm_handler(int sig) 312 { 313 received_sigterm = sig; 314 } 315 316 /* 317 * SIGCHLD handler. This is called whenever a child dies. This will then 318 * reap any zombies left by exited children. 319 */ 320 /*ARGSUSED*/ 321 static void 322 main_sigchld_handler(int sig) 323 { 324 int save_errno = errno; 325 pid_t pid; 326 int status; 327 328 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 329 (pid < 0 && errno == EINTR)) 330 ; 331 332 signal(SIGCHLD, main_sigchld_handler); 333 errno = save_errno; 334 } 335 336 /* 337 * Signal handler for the alarm after the login grace period has expired. 338 */ 339 /*ARGSUSED*/ 340 static void 341 grace_alarm_handler(int sig) 342 { 343 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 344 kill(pmonitor->m_pid, SIGALRM); 345 346 /* 347 * Try to kill any processes that we have spawned, E.g. authorized 348 * keys command helpers. 349 */ 350 if (getpgid(0) == getpid()) { 351 signal(SIGTERM, SIG_IGN); 352 kill(0, SIGTERM); 353 } 354 355 /* Log error and exit. */ 356 sigdie("Timeout before authentication for %s port %d", 357 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state)); 358 } 359 360 static void 361 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) 362 { 363 u_int i; 364 int remote_major, remote_minor; 365 char *s; 366 char buf[256]; /* Must not be larger than remote_version. */ 367 char remote_version[256]; /* Must be at least as big as buf. */ 368 369 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n", 370 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION, 371 *options.version_addendum == '\0' ? "" : " ", 372 options.version_addendum); 373 374 /* Send our protocol version identification. */ 375 if (atomicio(vwrite, sock_out, server_version_string, 376 strlen(server_version_string)) 377 != strlen(server_version_string)) { 378 logit("Could not write ident string to %s port %d", 379 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 380 cleanup_exit(255); 381 } 382 383 /* Read other sides version identification. */ 384 memset(buf, 0, sizeof(buf)); 385 for (i = 0; i < sizeof(buf) - 1; i++) { 386 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 387 logit("Did not receive identification string " 388 "from %s port %d", 389 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 390 cleanup_exit(255); 391 } 392 if (buf[i] == '\r') { 393 buf[i] = 0; 394 /* Kludge for F-Secure Macintosh < 1.0.2 */ 395 if (i == 12 && 396 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 397 break; 398 continue; 399 } 400 if (buf[i] == '\n') { 401 buf[i] = 0; 402 break; 403 } 404 } 405 buf[sizeof(buf) - 1] = 0; 406 client_version_string = xstrdup(buf); 407 408 /* 409 * Check that the versions match. In future this might accept 410 * several versions and set appropriate flags to handle them. 411 */ 412 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 413 &remote_major, &remote_minor, remote_version) != 3) { 414 s = "Protocol mismatch.\n"; 415 (void) atomicio(vwrite, sock_out, s, strlen(s)); 416 logit("Bad protocol version identification '%.100s' " 417 "from %s port %d", client_version_string, 418 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 419 close(sock_in); 420 close(sock_out); 421 cleanup_exit(255); 422 } 423 debug("Client protocol version %d.%d; client software version %.100s", 424 remote_major, remote_minor, remote_version); 425 426 ssh->compat = compat_datafellows(remote_version); 427 428 if ((ssh->compat & SSH_BUG_PROBE) != 0) { 429 logit("probed from %s port %d with %s. Don't panic.", 430 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 431 client_version_string); 432 cleanup_exit(255); 433 } 434 if ((ssh->compat & SSH_BUG_SCANNER) != 0) { 435 logit("scanned from %s port %d with %s. Don't panic.", 436 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 437 client_version_string); 438 cleanup_exit(255); 439 } 440 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 441 logit("Client version \"%.100s\" uses unsafe RSA signature " 442 "scheme; disabling use of RSA keys", remote_version); 443 } 444 if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) { 445 fatal("Client version \"%.100s\" uses unsafe key agreement; " 446 "refusing connection", remote_version); 447 } 448 449 chop(server_version_string); 450 debug("Local version string %.200s", server_version_string); 451 452 if (remote_major == 2 || 453 (remote_major == 1 && remote_minor == 99)) { 454 enable_compat20(); 455 } else { 456 s = "Protocol major versions differ.\n"; 457 (void) atomicio(vwrite, sock_out, s, strlen(s)); 458 close(sock_in); 459 close(sock_out); 460 logit("Protocol major versions differ for %s port %d: " 461 "%.200s vs. %.200s", 462 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 463 server_version_string, client_version_string); 464 cleanup_exit(255); 465 } 466 } 467 468 /* Destroy the host and server keys. They will no longer be needed. */ 469 void 470 destroy_sensitive_data(void) 471 { 472 int i; 473 474 for (i = 0; i < options.num_host_key_files; i++) { 475 if (sensitive_data.host_keys[i]) { 476 key_free(sensitive_data.host_keys[i]); 477 sensitive_data.host_keys[i] = NULL; 478 } 479 if (sensitive_data.host_certificates[i]) { 480 key_free(sensitive_data.host_certificates[i]); 481 sensitive_data.host_certificates[i] = NULL; 482 } 483 } 484 } 485 486 /* Demote private to public keys for network child */ 487 void 488 demote_sensitive_data(void) 489 { 490 Key *tmp; 491 int i; 492 493 for (i = 0; i < options.num_host_key_files; i++) { 494 if (sensitive_data.host_keys[i]) { 495 tmp = key_demote(sensitive_data.host_keys[i]); 496 key_free(sensitive_data.host_keys[i]); 497 sensitive_data.host_keys[i] = tmp; 498 } 499 /* Certs do not need demotion */ 500 } 501 } 502 503 static void 504 reseed_prngs(void) 505 { 506 u_int32_t rnd[256]; 507 508 #ifdef WITH_OPENSSL 509 RAND_poll(); 510 #endif 511 arc4random_stir(); /* noop on recent arc4random() implementations */ 512 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 513 514 #ifdef WITH_OPENSSL 515 RAND_seed(rnd, sizeof(rnd)); 516 /* give libcrypto a chance to notice the PID change */ 517 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 518 fatal("%s: RAND_bytes failed", __func__); 519 #endif 520 521 explicit_bzero(rnd, sizeof(rnd)); 522 } 523 524 static void 525 privsep_preauth_child(void) 526 { 527 gid_t gidset[1]; 528 529 /* Enable challenge-response authentication for privilege separation */ 530 privsep_challenge_enable(); 531 532 #ifdef GSSAPI 533 /* Cache supported mechanism OIDs for later use */ 534 if (options.gss_authentication) 535 ssh_gssapi_prepare_supported_oids(); 536 #endif 537 538 reseed_prngs(); 539 540 /* Demote the private keys to public keys. */ 541 demote_sensitive_data(); 542 543 /* Demote the child */ 544 if (getuid() == 0 || geteuid() == 0) { 545 /* Change our root directory */ 546 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 547 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 548 strerror(errno)); 549 if (chdir("/") == -1) 550 fatal("chdir(\"/\"): %s", strerror(errno)); 551 552 /* Drop our privileges */ 553 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 554 (u_int)privsep_pw->pw_gid); 555 gidset[0] = privsep_pw->pw_gid; 556 if (setgroups(1, gidset) < 0) 557 fatal("setgroups: %.100s", strerror(errno)); 558 permanently_set_uid(privsep_pw); 559 } 560 } 561 562 static int 563 privsep_preauth(Authctxt *authctxt) 564 { 565 int status, r; 566 pid_t pid; 567 struct ssh_sandbox *box = NULL; 568 569 /* Set up unprivileged child process to deal with network data */ 570 pmonitor = monitor_init(); 571 /* Store a pointer to the kex for later rekeying */ 572 pmonitor->m_pkex = &active_state->kex; 573 574 if (use_privsep == PRIVSEP_ON) 575 box = ssh_sandbox_init(pmonitor); 576 pid = fork(); 577 if (pid == -1) { 578 fatal("fork of unprivileged child failed"); 579 } else if (pid != 0) { 580 debug2("Network child is on pid %ld", (long)pid); 581 582 pmonitor->m_pid = pid; 583 if (have_agent) { 584 r = ssh_get_authentication_socket(&auth_sock); 585 if (r != 0) { 586 error("Could not get agent socket: %s", 587 ssh_err(r)); 588 have_agent = 0; 589 } 590 } 591 if (box != NULL) 592 ssh_sandbox_parent_preauth(box, pid); 593 monitor_child_preauth(authctxt, pmonitor); 594 595 /* Wait for the child's exit status */ 596 while (waitpid(pid, &status, 0) < 0) { 597 if (errno == EINTR) 598 continue; 599 pmonitor->m_pid = -1; 600 fatal("%s: waitpid: %s", __func__, strerror(errno)); 601 } 602 privsep_is_preauth = 0; 603 pmonitor->m_pid = -1; 604 if (WIFEXITED(status)) { 605 if (WEXITSTATUS(status) != 0) 606 fatal("%s: preauth child exited with status %d", 607 __func__, WEXITSTATUS(status)); 608 } else if (WIFSIGNALED(status)) 609 fatal("%s: preauth child terminated by signal %d", 610 __func__, WTERMSIG(status)); 611 if (box != NULL) 612 ssh_sandbox_parent_finish(box); 613 return 1; 614 } else { 615 /* child */ 616 close(pmonitor->m_sendfd); 617 close(pmonitor->m_log_recvfd); 618 619 /* Arrange for logging to be sent to the monitor */ 620 set_log_handler(mm_log_handler, pmonitor); 621 622 privsep_preauth_child(); 623 setproctitle("%s", "[net]"); 624 if (box != NULL) 625 ssh_sandbox_child(box); 626 627 return 0; 628 } 629 } 630 631 static void 632 privsep_postauth(Authctxt *authctxt) 633 { 634 #ifdef DISABLE_FD_PASSING 635 if (1) { 636 #else 637 if (authctxt->pw->pw_uid == 0) { 638 #endif 639 /* File descriptor passing is broken or root login */ 640 use_privsep = 0; 641 goto skip; 642 } 643 644 /* New socket pair */ 645 monitor_reinit(pmonitor); 646 647 pmonitor->m_pid = fork(); 648 if (pmonitor->m_pid == -1) 649 fatal("fork of unprivileged child failed"); 650 else if (pmonitor->m_pid != 0) { 651 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 652 buffer_clear(&loginmsg); 653 monitor_child_postauth(pmonitor); 654 655 /* NEVERREACHED */ 656 exit(0); 657 } 658 659 /* child */ 660 661 close(pmonitor->m_sendfd); 662 pmonitor->m_sendfd = -1; 663 664 /* Demote the private keys to public keys. */ 665 demote_sensitive_data(); 666 667 reseed_prngs(); 668 669 /* Drop privileges */ 670 do_setusercontext(authctxt->pw); 671 672 skip: 673 /* It is safe now to apply the key state */ 674 monitor_apply_keystate(pmonitor); 675 676 /* 677 * Tell the packet layer that authentication was successful, since 678 * this information is not part of the key state. 679 */ 680 packet_set_authenticated(); 681 } 682 683 static char * 684 list_hostkey_types(void) 685 { 686 Buffer b; 687 const char *p; 688 char *ret; 689 int i; 690 Key *key; 691 692 buffer_init(&b); 693 for (i = 0; i < options.num_host_key_files; i++) { 694 key = sensitive_data.host_keys[i]; 695 if (key == NULL) 696 key = sensitive_data.host_pubkeys[i]; 697 if (key == NULL) 698 continue; 699 /* Check that the key is accepted in HostkeyAlgorithms */ 700 if (match_pattern_list(sshkey_ssh_name(key), 701 options.hostkeyalgorithms, 0) != 1) { 702 debug3("%s: %s key not permitted by HostkeyAlgorithms", 703 __func__, sshkey_ssh_name(key)); 704 continue; 705 } 706 switch (key->type) { 707 case KEY_RSA: 708 case KEY_DSA: 709 case KEY_ECDSA: 710 case KEY_ED25519: 711 if (buffer_len(&b) > 0) 712 buffer_append(&b, ",", 1); 713 p = key_ssh_name(key); 714 buffer_append(&b, p, strlen(p)); 715 716 /* for RSA we also support SHA2 signatures */ 717 if (key->type == KEY_RSA) { 718 p = ",rsa-sha2-512,rsa-sha2-256"; 719 buffer_append(&b, p, strlen(p)); 720 } 721 break; 722 } 723 /* If the private key has a cert peer, then list that too */ 724 key = sensitive_data.host_certificates[i]; 725 if (key == NULL) 726 continue; 727 switch (key->type) { 728 case KEY_RSA_CERT: 729 case KEY_DSA_CERT: 730 case KEY_ECDSA_CERT: 731 case KEY_ED25519_CERT: 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 break; 737 } 738 } 739 if ((ret = sshbuf_dup_string(&b)) == NULL) 740 fatal("%s: sshbuf_dup_string failed", __func__); 741 buffer_free(&b); 742 debug("list_hostkey_types: %s", ret); 743 return ret; 744 } 745 746 static Key * 747 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 748 { 749 int i; 750 Key *key; 751 752 for (i = 0; i < options.num_host_key_files; i++) { 753 switch (type) { 754 case KEY_RSA_CERT: 755 case KEY_DSA_CERT: 756 case KEY_ECDSA_CERT: 757 case KEY_ED25519_CERT: 758 key = sensitive_data.host_certificates[i]; 759 break; 760 default: 761 key = sensitive_data.host_keys[i]; 762 if (key == NULL && !need_private) 763 key = sensitive_data.host_pubkeys[i]; 764 break; 765 } 766 if (key != NULL && key->type == type && 767 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 768 return need_private ? 769 sensitive_data.host_keys[i] : key; 770 } 771 return NULL; 772 } 773 774 Key * 775 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 776 { 777 return get_hostkey_by_type(type, nid, 0, ssh); 778 } 779 780 Key * 781 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 782 { 783 return get_hostkey_by_type(type, nid, 1, ssh); 784 } 785 786 Key * 787 get_hostkey_by_index(int ind) 788 { 789 if (ind < 0 || ind >= options.num_host_key_files) 790 return (NULL); 791 return (sensitive_data.host_keys[ind]); 792 } 793 794 Key * 795 get_hostkey_public_by_index(int ind, struct ssh *ssh) 796 { 797 if (ind < 0 || ind >= options.num_host_key_files) 798 return (NULL); 799 return (sensitive_data.host_pubkeys[ind]); 800 } 801 802 int 803 get_hostkey_index(Key *key, int compare, struct ssh *ssh) 804 { 805 int i; 806 807 for (i = 0; i < options.num_host_key_files; i++) { 808 if (key_is_cert(key)) { 809 if (key == sensitive_data.host_certificates[i] || 810 (compare && sensitive_data.host_certificates[i] && 811 sshkey_equal(key, 812 sensitive_data.host_certificates[i]))) 813 return (i); 814 } else { 815 if (key == sensitive_data.host_keys[i] || 816 (compare && sensitive_data.host_keys[i] && 817 sshkey_equal(key, sensitive_data.host_keys[i]))) 818 return (i); 819 if (key == sensitive_data.host_pubkeys[i] || 820 (compare && sensitive_data.host_pubkeys[i] && 821 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 822 return (i); 823 } 824 } 825 return (-1); 826 } 827 828 /* Inform the client of all hostkeys */ 829 static void 830 notify_hostkeys(struct ssh *ssh) 831 { 832 struct sshbuf *buf; 833 struct sshkey *key; 834 int i, nkeys, r; 835 char *fp; 836 837 /* Some clients cannot cope with the hostkeys message, skip those. */ 838 if (datafellows & SSH_BUG_HOSTKEYS) 839 return; 840 841 if ((buf = sshbuf_new()) == NULL) 842 fatal("%s: sshbuf_new", __func__); 843 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 844 key = get_hostkey_public_by_index(i, ssh); 845 if (key == NULL || key->type == KEY_UNSPEC || 846 sshkey_is_cert(key)) 847 continue; 848 fp = sshkey_fingerprint(key, options.fingerprint_hash, 849 SSH_FP_DEFAULT); 850 debug3("%s: key %d: %s %s", __func__, i, 851 sshkey_ssh_name(key), fp); 852 free(fp); 853 if (nkeys == 0) { 854 packet_start(SSH2_MSG_GLOBAL_REQUEST); 855 packet_put_cstring("hostkeys-00 (at) openssh.com"); 856 packet_put_char(0); /* want-reply */ 857 } 858 sshbuf_reset(buf); 859 if ((r = sshkey_putb(key, buf)) != 0) 860 fatal("%s: couldn't put hostkey %d: %s", 861 __func__, i, ssh_err(r)); 862 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 863 nkeys++; 864 } 865 debug3("%s: sent %d hostkeys", __func__, nkeys); 866 if (nkeys == 0) 867 fatal("%s: no hostkeys", __func__); 868 packet_send(); 869 sshbuf_free(buf); 870 } 871 872 /* 873 * returns 1 if connection should be dropped, 0 otherwise. 874 * dropping starts at connection #max_startups_begin with a probability 875 * of (max_startups_rate/100). the probability increases linearly until 876 * all connections are dropped for startups > max_startups 877 */ 878 static int 879 drop_connection(int startups) 880 { 881 int p, r; 882 883 if (startups < options.max_startups_begin) 884 return 0; 885 if (startups >= options.max_startups) 886 return 1; 887 if (options.max_startups_rate == 100) 888 return 1; 889 890 p = 100 - options.max_startups_rate; 891 p *= startups - options.max_startups_begin; 892 p /= options.max_startups - options.max_startups_begin; 893 p += options.max_startups_rate; 894 r = arc4random_uniform(100); 895 896 debug("drop_connection: p %d, r %d", p, r); 897 return (r < p) ? 1 : 0; 898 } 899 900 static void 901 usage(void) 902 { 903 fprintf(stderr, "%s, %s\n", 904 SSH_RELEASE, 905 #ifdef WITH_OPENSSL 906 SSLeay_version(SSLEAY_VERSION) 907 #else 908 "without OpenSSL" 909 #endif 910 ); 911 fprintf(stderr, 912 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 913 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 914 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 915 ); 916 exit(1); 917 } 918 919 static void 920 send_rexec_state(int fd, struct sshbuf *conf) 921 { 922 struct sshbuf *m; 923 int r; 924 925 debug3("%s: entering fd = %d config len %zu", __func__, fd, 926 sshbuf_len(conf)); 927 928 /* 929 * Protocol from reexec master to child: 930 * string configuration 931 * string rngseed (only if OpenSSL is not self-seeded) 932 */ 933 if ((m = sshbuf_new()) == NULL) 934 fatal("%s: sshbuf_new failed", __func__); 935 if ((r = sshbuf_put_stringb(m, conf)) != 0) 936 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 937 938 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 939 rexec_send_rng_seed(m); 940 #endif 941 942 if (ssh_msg_send(fd, 0, m) == -1) 943 fatal("%s: ssh_msg_send failed", __func__); 944 945 sshbuf_free(m); 946 947 debug3("%s: done", __func__); 948 } 949 950 static void 951 recv_rexec_state(int fd, Buffer *conf) 952 { 953 Buffer m; 954 char *cp; 955 u_int len; 956 957 debug3("%s: entering fd = %d", __func__, fd); 958 959 buffer_init(&m); 960 961 if (ssh_msg_recv(fd, &m) == -1) 962 fatal("%s: ssh_msg_recv failed", __func__); 963 if (buffer_get_char(&m) != 0) 964 fatal("%s: rexec version mismatch", __func__); 965 966 cp = buffer_get_string(&m, &len); 967 if (conf != NULL) 968 buffer_append(conf, cp, len); 969 free(cp); 970 971 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 972 rexec_recv_rng_seed(&m); 973 #endif 974 975 buffer_free(&m); 976 977 debug3("%s: done", __func__); 978 } 979 980 /* Accept a connection from inetd */ 981 static void 982 server_accept_inetd(int *sock_in, int *sock_out) 983 { 984 int fd; 985 986 startup_pipe = -1; 987 if (rexeced_flag) { 988 close(REEXEC_CONFIG_PASS_FD); 989 *sock_in = *sock_out = dup(STDIN_FILENO); 990 if (!debug_flag) { 991 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 992 close(REEXEC_STARTUP_PIPE_FD); 993 } 994 } else { 995 *sock_in = dup(STDIN_FILENO); 996 *sock_out = dup(STDOUT_FILENO); 997 } 998 /* 999 * We intentionally do not close the descriptors 0, 1, and 2 1000 * as our code for setting the descriptors won't work if 1001 * ttyfd happens to be one of those. 1002 */ 1003 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1004 dup2(fd, STDIN_FILENO); 1005 dup2(fd, STDOUT_FILENO); 1006 if (!log_stderr) 1007 dup2(fd, STDERR_FILENO); 1008 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1009 close(fd); 1010 } 1011 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1012 } 1013 1014 /* 1015 * Listen for TCP connections 1016 */ 1017 static void 1018 server_listen(void) 1019 { 1020 int ret, listen_sock, on = 1; 1021 struct addrinfo *ai; 1022 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1023 1024 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1025 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1026 continue; 1027 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1028 fatal("Too many listen sockets. " 1029 "Enlarge MAX_LISTEN_SOCKS"); 1030 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1031 ntop, sizeof(ntop), strport, sizeof(strport), 1032 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1033 error("getnameinfo failed: %.100s", 1034 ssh_gai_strerror(ret)); 1035 continue; 1036 } 1037 /* Create socket for listening. */ 1038 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1039 ai->ai_protocol); 1040 if (listen_sock < 0) { 1041 /* kernel may not support ipv6 */ 1042 verbose("socket: %.100s", strerror(errno)); 1043 continue; 1044 } 1045 if (set_nonblock(listen_sock) == -1) { 1046 close(listen_sock); 1047 continue; 1048 } 1049 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1050 verbose("socket: CLOEXEC: %s", strerror(errno)); 1051 close(listen_sock); 1052 continue; 1053 } 1054 /* 1055 * Set socket options. 1056 * Allow local port reuse in TIME_WAIT. 1057 */ 1058 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1059 &on, sizeof(on)) == -1) 1060 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1061 1062 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1063 if (ai->ai_family == AF_INET6) 1064 sock_set_v6only(listen_sock); 1065 1066 debug("Bind to port %s on %s.", strport, ntop); 1067 1068 /* Bind the socket to the desired port. */ 1069 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1070 error("Bind to port %s on %s failed: %.200s.", 1071 strport, ntop, strerror(errno)); 1072 close(listen_sock); 1073 continue; 1074 } 1075 listen_socks[num_listen_socks] = listen_sock; 1076 num_listen_socks++; 1077 1078 /* Start listening on the port. */ 1079 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1080 fatal("listen on [%s]:%s: %.100s", 1081 ntop, strport, strerror(errno)); 1082 logit("Server listening on %s port %s.", ntop, strport); 1083 } 1084 freeaddrinfo(options.listen_addrs); 1085 1086 if (!num_listen_socks) 1087 fatal("Cannot bind any address."); 1088 } 1089 1090 /* 1091 * The main TCP accept loop. Note that, for the non-debug case, returns 1092 * from this function are in a forked subprocess. 1093 */ 1094 static void 1095 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1096 { 1097 fd_set *fdset; 1098 int i, j, ret, maxfd; 1099 int startups = 0; 1100 int startup_p[2] = { -1 , -1 }; 1101 struct sockaddr_storage from; 1102 socklen_t fromlen; 1103 pid_t pid; 1104 u_char rnd[256]; 1105 1106 /* setup fd set for accept */ 1107 fdset = NULL; 1108 maxfd = 0; 1109 for (i = 0; i < num_listen_socks; i++) 1110 if (listen_socks[i] > maxfd) 1111 maxfd = listen_socks[i]; 1112 /* pipes connected to unauthenticated childs */ 1113 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1114 for (i = 0; i < options.max_startups; i++) 1115 startup_pipes[i] = -1; 1116 1117 /* 1118 * Stay listening for connections until the system crashes or 1119 * the daemon is killed with a signal. 1120 */ 1121 for (;;) { 1122 if (received_sighup) 1123 sighup_restart(); 1124 free(fdset); 1125 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1126 sizeof(fd_mask)); 1127 1128 for (i = 0; i < num_listen_socks; i++) 1129 FD_SET(listen_socks[i], fdset); 1130 for (i = 0; i < options.max_startups; i++) 1131 if (startup_pipes[i] != -1) 1132 FD_SET(startup_pipes[i], fdset); 1133 1134 /* Wait in select until there is a connection. */ 1135 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1136 if (ret < 0 && errno != EINTR) 1137 error("select: %.100s", strerror(errno)); 1138 if (received_sigterm) { 1139 logit("Received signal %d; terminating.", 1140 (int) received_sigterm); 1141 close_listen_socks(); 1142 if (options.pid_file != NULL) 1143 unlink(options.pid_file); 1144 exit(received_sigterm == SIGTERM ? 0 : 255); 1145 } 1146 if (ret < 0) 1147 continue; 1148 1149 for (i = 0; i < options.max_startups; i++) 1150 if (startup_pipes[i] != -1 && 1151 FD_ISSET(startup_pipes[i], fdset)) { 1152 /* 1153 * the read end of the pipe is ready 1154 * if the child has closed the pipe 1155 * after successful authentication 1156 * or if the child has died 1157 */ 1158 close(startup_pipes[i]); 1159 startup_pipes[i] = -1; 1160 startups--; 1161 } 1162 for (i = 0; i < num_listen_socks; i++) { 1163 if (!FD_ISSET(listen_socks[i], fdset)) 1164 continue; 1165 fromlen = sizeof(from); 1166 *newsock = accept(listen_socks[i], 1167 (struct sockaddr *)&from, &fromlen); 1168 if (*newsock < 0) { 1169 if (errno != EINTR && errno != EWOULDBLOCK && 1170 errno != ECONNABORTED && errno != EAGAIN) 1171 error("accept: %.100s", 1172 strerror(errno)); 1173 if (errno == EMFILE || errno == ENFILE) 1174 usleep(100 * 1000); 1175 continue; 1176 } 1177 if (unset_nonblock(*newsock) == -1) { 1178 close(*newsock); 1179 continue; 1180 } 1181 if (drop_connection(startups) == 1) { 1182 char *laddr = get_local_ipaddr(*newsock); 1183 char *raddr = get_peer_ipaddr(*newsock); 1184 1185 verbose("drop connection #%d from [%s]:%d " 1186 "on [%s]:%d past MaxStartups", startups, 1187 raddr, get_peer_port(*newsock), 1188 laddr, get_local_port(*newsock)); 1189 free(laddr); 1190 free(raddr); 1191 close(*newsock); 1192 continue; 1193 } 1194 if (pipe(startup_p) == -1) { 1195 close(*newsock); 1196 continue; 1197 } 1198 1199 if (rexec_flag && socketpair(AF_UNIX, 1200 SOCK_STREAM, 0, config_s) == -1) { 1201 error("reexec socketpair: %s", 1202 strerror(errno)); 1203 close(*newsock); 1204 close(startup_p[0]); 1205 close(startup_p[1]); 1206 continue; 1207 } 1208 1209 for (j = 0; j < options.max_startups; j++) 1210 if (startup_pipes[j] == -1) { 1211 startup_pipes[j] = startup_p[0]; 1212 if (maxfd < startup_p[0]) 1213 maxfd = startup_p[0]; 1214 startups++; 1215 break; 1216 } 1217 1218 /* 1219 * Got connection. Fork a child to handle it, unless 1220 * we are in debugging mode. 1221 */ 1222 if (debug_flag) { 1223 /* 1224 * In debugging mode. Close the listening 1225 * socket, and start processing the 1226 * connection without forking. 1227 */ 1228 debug("Server will not fork when running in debugging mode."); 1229 close_listen_socks(); 1230 *sock_in = *newsock; 1231 *sock_out = *newsock; 1232 close(startup_p[0]); 1233 close(startup_p[1]); 1234 startup_pipe = -1; 1235 pid = getpid(); 1236 if (rexec_flag) { 1237 send_rexec_state(config_s[0], 1238 &cfg); 1239 close(config_s[0]); 1240 } 1241 break; 1242 } 1243 1244 /* 1245 * Normal production daemon. Fork, and have 1246 * the child process the connection. The 1247 * parent continues listening. 1248 */ 1249 platform_pre_fork(); 1250 if ((pid = fork()) == 0) { 1251 /* 1252 * Child. Close the listening and 1253 * max_startup sockets. Start using 1254 * the accepted socket. Reinitialize 1255 * logging (since our pid has changed). 1256 * We break out of the loop to handle 1257 * the connection. 1258 */ 1259 platform_post_fork_child(); 1260 startup_pipe = startup_p[1]; 1261 close_startup_pipes(); 1262 close_listen_socks(); 1263 *sock_in = *newsock; 1264 *sock_out = *newsock; 1265 log_init(__progname, 1266 options.log_level, 1267 options.log_facility, 1268 log_stderr); 1269 if (rexec_flag) 1270 close(config_s[0]); 1271 break; 1272 } 1273 1274 /* Parent. Stay in the loop. */ 1275 platform_post_fork_parent(pid); 1276 if (pid < 0) 1277 error("fork: %.100s", strerror(errno)); 1278 else 1279 debug("Forked child %ld.", (long)pid); 1280 1281 close(startup_p[1]); 1282 1283 if (rexec_flag) { 1284 send_rexec_state(config_s[0], &cfg); 1285 close(config_s[0]); 1286 close(config_s[1]); 1287 } 1288 close(*newsock); 1289 1290 /* 1291 * Ensure that our random state differs 1292 * from that of the child 1293 */ 1294 arc4random_stir(); 1295 arc4random_buf(rnd, sizeof(rnd)); 1296 #ifdef WITH_OPENSSL 1297 RAND_seed(rnd, sizeof(rnd)); 1298 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1299 fatal("%s: RAND_bytes failed", __func__); 1300 #endif 1301 explicit_bzero(rnd, sizeof(rnd)); 1302 } 1303 1304 /* child process check (or debug mode) */ 1305 if (num_listen_socks < 0) 1306 break; 1307 } 1308 } 1309 1310 /* 1311 * If IP options are supported, make sure there are none (log and 1312 * return an error if any are found). Basically we are worried about 1313 * source routing; it can be used to pretend you are somebody 1314 * (ip-address) you are not. That itself may be "almost acceptable" 1315 * under certain circumstances, but rhosts autentication is useless 1316 * if source routing is accepted. Notice also that if we just dropped 1317 * source routing here, the other side could use IP spoofing to do 1318 * rest of the interaction and could still bypass security. So we 1319 * exit here if we detect any IP options. 1320 */ 1321 static void 1322 check_ip_options(struct ssh *ssh) 1323 { 1324 #ifdef IP_OPTIONS 1325 int sock_in = ssh_packet_get_connection_in(ssh); 1326 struct sockaddr_storage from; 1327 u_char opts[200]; 1328 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1329 char text[sizeof(opts) * 3 + 1]; 1330 1331 memset(&from, 0, sizeof(from)); 1332 if (getpeername(sock_in, (struct sockaddr *)&from, 1333 &fromlen) < 0) 1334 return; 1335 if (from.ss_family != AF_INET) 1336 return; 1337 /* XXX IPv6 options? */ 1338 1339 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1340 &option_size) >= 0 && option_size != 0) { 1341 text[0] = '\0'; 1342 for (i = 0; i < option_size; i++) 1343 snprintf(text + i*3, sizeof(text) - i*3, 1344 " %2.2x", opts[i]); 1345 fatal("Connection from %.100s port %d with IP opts: %.800s", 1346 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1347 } 1348 return; 1349 #endif /* IP_OPTIONS */ 1350 } 1351 1352 /* 1353 * Main program for the daemon. 1354 */ 1355 int 1356 main(int ac, char **av) 1357 { 1358 struct ssh *ssh = NULL; 1359 extern char *optarg; 1360 extern int optind; 1361 int r, opt, i, j, on = 1, already_daemon; 1362 int sock_in = -1, sock_out = -1, newsock = -1; 1363 const char *remote_ip; 1364 int remote_port; 1365 char *fp, *line, *laddr, *logfile = NULL; 1366 int config_s[2] = { -1 , -1 }; 1367 u_int n; 1368 u_int64_t ibytes, obytes; 1369 mode_t new_umask; 1370 Key *key; 1371 Key *pubkey; 1372 int keytype; 1373 Authctxt *authctxt; 1374 struct connection_info *connection_info = get_connection_info(0, 0); 1375 1376 ssh_malloc_init(); /* must be called before any mallocs */ 1377 1378 #ifdef HAVE_SECUREWARE 1379 (void)set_auth_parameters(ac, av); 1380 #endif 1381 __progname = ssh_get_progname(av[0]); 1382 1383 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1384 saved_argc = ac; 1385 rexec_argc = ac; 1386 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1387 for (i = 0; i < ac; i++) 1388 saved_argv[i] = xstrdup(av[i]); 1389 saved_argv[i] = NULL; 1390 1391 #ifndef HAVE_SETPROCTITLE 1392 /* Prepare for later setproctitle emulation */ 1393 compat_init_setproctitle(ac, av); 1394 av = saved_argv; 1395 #endif 1396 1397 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1398 debug("setgroups(): %.200s", strerror(errno)); 1399 1400 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1401 sanitise_stdfd(); 1402 1403 /* Initialize configuration options to their default values. */ 1404 initialize_server_options(&options); 1405 1406 /* Parse command-line arguments. */ 1407 while ((opt = getopt(ac, av, 1408 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1409 switch (opt) { 1410 case '4': 1411 options.address_family = AF_INET; 1412 break; 1413 case '6': 1414 options.address_family = AF_INET6; 1415 break; 1416 case 'f': 1417 config_file_name = optarg; 1418 break; 1419 case 'c': 1420 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1421 fprintf(stderr, "too many host certificates.\n"); 1422 exit(1); 1423 } 1424 options.host_cert_files[options.num_host_cert_files++] = 1425 derelativise_path(optarg); 1426 break; 1427 case 'd': 1428 if (debug_flag == 0) { 1429 debug_flag = 1; 1430 options.log_level = SYSLOG_LEVEL_DEBUG1; 1431 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1432 options.log_level++; 1433 break; 1434 case 'D': 1435 no_daemon_flag = 1; 1436 break; 1437 case 'E': 1438 logfile = optarg; 1439 /* FALLTHROUGH */ 1440 case 'e': 1441 log_stderr = 1; 1442 break; 1443 case 'i': 1444 inetd_flag = 1; 1445 break; 1446 case 'r': 1447 rexec_flag = 0; 1448 break; 1449 case 'R': 1450 rexeced_flag = 1; 1451 inetd_flag = 1; 1452 break; 1453 case 'Q': 1454 /* ignored */ 1455 break; 1456 case 'q': 1457 options.log_level = SYSLOG_LEVEL_QUIET; 1458 break; 1459 case 'b': 1460 /* protocol 1, ignored */ 1461 break; 1462 case 'p': 1463 options.ports_from_cmdline = 1; 1464 if (options.num_ports >= MAX_PORTS) { 1465 fprintf(stderr, "too many ports.\n"); 1466 exit(1); 1467 } 1468 options.ports[options.num_ports++] = a2port(optarg); 1469 if (options.ports[options.num_ports-1] <= 0) { 1470 fprintf(stderr, "Bad port number.\n"); 1471 exit(1); 1472 } 1473 break; 1474 case 'g': 1475 if ((options.login_grace_time = convtime(optarg)) == -1) { 1476 fprintf(stderr, "Invalid login grace time.\n"); 1477 exit(1); 1478 } 1479 break; 1480 case 'k': 1481 /* protocol 1, ignored */ 1482 break; 1483 case 'h': 1484 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1485 fprintf(stderr, "too many host keys.\n"); 1486 exit(1); 1487 } 1488 options.host_key_files[options.num_host_key_files++] = 1489 derelativise_path(optarg); 1490 break; 1491 case 't': 1492 test_flag = 1; 1493 break; 1494 case 'T': 1495 test_flag = 2; 1496 break; 1497 case 'C': 1498 if (parse_server_match_testspec(connection_info, 1499 optarg) == -1) 1500 exit(1); 1501 break; 1502 case 'u': 1503 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1504 if (utmp_len > HOST_NAME_MAX+1) { 1505 fprintf(stderr, "Invalid utmp length.\n"); 1506 exit(1); 1507 } 1508 break; 1509 case 'o': 1510 line = xstrdup(optarg); 1511 if (process_server_config_line(&options, line, 1512 "command-line", 0, NULL, NULL) != 0) 1513 exit(1); 1514 free(line); 1515 break; 1516 case '?': 1517 default: 1518 usage(); 1519 break; 1520 } 1521 } 1522 if (rexeced_flag || inetd_flag) 1523 rexec_flag = 0; 1524 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1525 fatal("sshd re-exec requires execution with an absolute path"); 1526 if (rexeced_flag) 1527 closefrom(REEXEC_MIN_FREE_FD); 1528 else 1529 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1530 1531 #ifdef WITH_OPENSSL 1532 OpenSSL_add_all_algorithms(); 1533 #endif 1534 1535 /* If requested, redirect the logs to the specified logfile. */ 1536 if (logfile != NULL) 1537 log_redirect_stderr_to(logfile); 1538 /* 1539 * Force logging to stderr until we have loaded the private host 1540 * key (unless started from inetd) 1541 */ 1542 log_init(__progname, 1543 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1544 SYSLOG_LEVEL_INFO : options.log_level, 1545 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1546 SYSLOG_FACILITY_AUTH : options.log_facility, 1547 log_stderr || !inetd_flag); 1548 1549 /* 1550 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1551 * root's environment 1552 */ 1553 if (getenv("KRB5CCNAME") != NULL) 1554 (void) unsetenv("KRB5CCNAME"); 1555 1556 #ifdef _UNICOS 1557 /* Cray can define user privs drop all privs now! 1558 * Not needed on PRIV_SU systems! 1559 */ 1560 drop_cray_privs(); 1561 #endif 1562 1563 sensitive_data.have_ssh2_key = 0; 1564 1565 /* 1566 * If we're doing an extended config test, make sure we have all of 1567 * the parameters we need. If we're not doing an extended test, 1568 * do not silently ignore connection test params. 1569 */ 1570 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1571 fatal("user, host and addr are all required when testing " 1572 "Match configs"); 1573 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1574 fatal("Config test connection parameter (-C) provided without " 1575 "test mode (-T)"); 1576 1577 /* Fetch our configuration */ 1578 buffer_init(&cfg); 1579 if (rexeced_flag) 1580 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1581 else if (strcasecmp(config_file_name, "none") != 0) 1582 load_server_config(config_file_name, &cfg); 1583 1584 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1585 &cfg, NULL); 1586 1587 seed_rng(); 1588 1589 /* Fill in default values for those options not explicitly set. */ 1590 fill_default_server_options(&options); 1591 1592 /* challenge-response is implemented via keyboard interactive */ 1593 if (options.challenge_response_authentication) 1594 options.kbd_interactive_authentication = 1; 1595 1596 /* Check that options are sensible */ 1597 if (options.authorized_keys_command_user == NULL && 1598 (options.authorized_keys_command != NULL && 1599 strcasecmp(options.authorized_keys_command, "none") != 0)) 1600 fatal("AuthorizedKeysCommand set without " 1601 "AuthorizedKeysCommandUser"); 1602 if (options.authorized_principals_command_user == NULL && 1603 (options.authorized_principals_command != NULL && 1604 strcasecmp(options.authorized_principals_command, "none") != 0)) 1605 fatal("AuthorizedPrincipalsCommand set without " 1606 "AuthorizedPrincipalsCommandUser"); 1607 1608 /* 1609 * Check whether there is any path through configured auth methods. 1610 * Unfortunately it is not possible to verify this generally before 1611 * daemonisation in the presence of Match block, but this catches 1612 * and warns for trivial misconfigurations that could break login. 1613 */ 1614 if (options.num_auth_methods != 0) { 1615 for (n = 0; n < options.num_auth_methods; n++) { 1616 if (auth2_methods_valid(options.auth_methods[n], 1617 1) == 0) 1618 break; 1619 } 1620 if (n >= options.num_auth_methods) 1621 fatal("AuthenticationMethods cannot be satisfied by " 1622 "enabled authentication methods"); 1623 } 1624 1625 /* set default channel AF */ 1626 channel_set_af(options.address_family); 1627 1628 /* Check that there are no remaining arguments. */ 1629 if (optind < ac) { 1630 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1631 exit(1); 1632 } 1633 1634 debug("sshd version %s, %s", SSH_VERSION, 1635 #ifdef WITH_OPENSSL 1636 SSLeay_version(SSLEAY_VERSION) 1637 #else 1638 "without OpenSSL" 1639 #endif 1640 ); 1641 1642 /* Store privilege separation user for later use if required. */ 1643 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1644 if (use_privsep || options.kerberos_authentication) 1645 fatal("Privilege separation user %s does not exist", 1646 SSH_PRIVSEP_USER); 1647 } else { 1648 #if defined(ANDROID) 1649 /* Android does not do passwords and passes NULL for them. This breaks strlen */ 1650 if (privsep_pw->pw_passwd) { 1651 #endif 1652 explicit_bzero(privsep_pw->pw_passwd, 1653 strlen(privsep_pw->pw_passwd)); 1654 privsep_pw = pwcopy(privsep_pw); 1655 free(privsep_pw->pw_passwd); 1656 #if defined(ANDROID) 1657 } 1658 #endif 1659 privsep_pw->pw_passwd = xstrdup("*"); 1660 } 1661 #if !defined(ANDROID) 1662 endpwent(); 1663 #endif 1664 1665 /* load host keys */ 1666 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1667 sizeof(Key *)); 1668 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1669 sizeof(Key *)); 1670 1671 if (options.host_key_agent) { 1672 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1673 setenv(SSH_AUTHSOCKET_ENV_NAME, 1674 options.host_key_agent, 1); 1675 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1676 have_agent = 1; 1677 else 1678 error("Could not connect to agent \"%s\": %s", 1679 options.host_key_agent, ssh_err(r)); 1680 } 1681 1682 for (i = 0; i < options.num_host_key_files; i++) { 1683 if (options.host_key_files[i] == NULL) 1684 continue; 1685 key = key_load_private(options.host_key_files[i], "", NULL); 1686 pubkey = key_load_public(options.host_key_files[i], NULL); 1687 1688 if ((pubkey != NULL && pubkey->type == KEY_RSA1) || 1689 (key != NULL && key->type == KEY_RSA1)) { 1690 verbose("Ignoring RSA1 key %s", 1691 options.host_key_files[i]); 1692 key_free(key); 1693 key_free(pubkey); 1694 continue; 1695 } 1696 if (pubkey == NULL && key != NULL) 1697 pubkey = key_demote(key); 1698 sensitive_data.host_keys[i] = key; 1699 sensitive_data.host_pubkeys[i] = pubkey; 1700 1701 if (key == NULL && pubkey != NULL && have_agent) { 1702 debug("will rely on agent for hostkey %s", 1703 options.host_key_files[i]); 1704 keytype = pubkey->type; 1705 } else if (key != NULL) { 1706 keytype = key->type; 1707 } else { 1708 error("Could not load host key: %s", 1709 options.host_key_files[i]); 1710 sensitive_data.host_keys[i] = NULL; 1711 sensitive_data.host_pubkeys[i] = NULL; 1712 continue; 1713 } 1714 1715 switch (keytype) { 1716 case KEY_RSA: 1717 case KEY_DSA: 1718 case KEY_ECDSA: 1719 case KEY_ED25519: 1720 if (have_agent || key != NULL) 1721 sensitive_data.have_ssh2_key = 1; 1722 break; 1723 } 1724 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1725 SSH_FP_DEFAULT)) == NULL) 1726 fatal("sshkey_fingerprint failed"); 1727 debug("%s host key #%d: %s %s", 1728 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1729 free(fp); 1730 } 1731 if (!sensitive_data.have_ssh2_key) { 1732 logit("sshd: no hostkeys available -- exiting."); 1733 exit(1); 1734 } 1735 1736 /* 1737 * Load certificates. They are stored in an array at identical 1738 * indices to the public keys that they relate to. 1739 */ 1740 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1741 sizeof(Key *)); 1742 for (i = 0; i < options.num_host_key_files; i++) 1743 sensitive_data.host_certificates[i] = NULL; 1744 1745 for (i = 0; i < options.num_host_cert_files; i++) { 1746 if (options.host_cert_files[i] == NULL) 1747 continue; 1748 key = key_load_public(options.host_cert_files[i], NULL); 1749 if (key == NULL) { 1750 error("Could not load host certificate: %s", 1751 options.host_cert_files[i]); 1752 continue; 1753 } 1754 if (!key_is_cert(key)) { 1755 error("Certificate file is not a certificate: %s", 1756 options.host_cert_files[i]); 1757 key_free(key); 1758 continue; 1759 } 1760 /* Find matching private key */ 1761 for (j = 0; j < options.num_host_key_files; j++) { 1762 if (key_equal_public(key, 1763 sensitive_data.host_keys[j])) { 1764 sensitive_data.host_certificates[j] = key; 1765 break; 1766 } 1767 } 1768 if (j >= options.num_host_key_files) { 1769 error("No matching private key for certificate: %s", 1770 options.host_cert_files[i]); 1771 key_free(key); 1772 continue; 1773 } 1774 sensitive_data.host_certificates[j] = key; 1775 debug("host certificate: #%d type %d %s", j, key->type, 1776 key_type(key)); 1777 } 1778 1779 if (use_privsep) { 1780 struct stat st; 1781 1782 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1783 (S_ISDIR(st.st_mode) == 0)) 1784 fatal("Missing privilege separation directory: %s", 1785 _PATH_PRIVSEP_CHROOT_DIR); 1786 1787 #ifdef HAVE_CYGWIN 1788 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1789 (st.st_uid != getuid () || 1790 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1791 #else 1792 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1793 #endif 1794 fatal("%s must be owned by root and not group or " 1795 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1796 } 1797 1798 if (test_flag > 1) { 1799 if (server_match_spec_complete(connection_info) == 1) 1800 parse_server_match_config(&options, connection_info); 1801 dump_config(&options); 1802 } 1803 1804 /* Configuration looks good, so exit if in test mode. */ 1805 if (test_flag) 1806 exit(0); 1807 1808 /* 1809 * Clear out any supplemental groups we may have inherited. This 1810 * prevents inadvertent creation of files with bad modes (in the 1811 * portable version at least, it's certainly possible for PAM 1812 * to create a file, and we can't control the code in every 1813 * module which might be used). 1814 */ 1815 if (setgroups(0, NULL) < 0) 1816 debug("setgroups() failed: %.200s", strerror(errno)); 1817 1818 if (rexec_flag) { 1819 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1820 for (i = 0; i < rexec_argc; i++) { 1821 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1822 rexec_argv[i] = saved_argv[i]; 1823 } 1824 rexec_argv[rexec_argc] = "-R"; 1825 rexec_argv[rexec_argc + 1] = NULL; 1826 } 1827 1828 /* Ensure that umask disallows at least group and world write */ 1829 new_umask = umask(0077) | 0022; 1830 (void) umask(new_umask); 1831 1832 /* Initialize the log (it is reinitialized below in case we forked). */ 1833 if (debug_flag && (!inetd_flag || rexeced_flag)) 1834 log_stderr = 1; 1835 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1836 1837 /* 1838 * If not in debugging mode, not started from inetd and not already 1839 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1840 * terminal, and fork. The original process exits. 1841 */ 1842 already_daemon = daemonized(); 1843 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1844 1845 if (daemon(0, 0) < 0) 1846 fatal("daemon() failed: %.200s", strerror(errno)); 1847 1848 disconnect_controlling_tty(); 1849 } 1850 /* Reinitialize the log (because of the fork above). */ 1851 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1852 1853 /* Chdir to the root directory so that the current disk can be 1854 unmounted if desired. */ 1855 if (chdir("/") == -1) 1856 error("chdir(\"/\"): %s", strerror(errno)); 1857 1858 /* ignore SIGPIPE */ 1859 signal(SIGPIPE, SIG_IGN); 1860 1861 /* Get a connection, either from inetd or a listening TCP socket */ 1862 if (inetd_flag) { 1863 server_accept_inetd(&sock_in, &sock_out); 1864 } else { 1865 platform_pre_listen(); 1866 server_listen(); 1867 1868 signal(SIGHUP, sighup_handler); 1869 signal(SIGCHLD, main_sigchld_handler); 1870 signal(SIGTERM, sigterm_handler); 1871 signal(SIGQUIT, sigterm_handler); 1872 1873 /* 1874 * Write out the pid file after the sigterm handler 1875 * is setup and the listen sockets are bound 1876 */ 1877 if (options.pid_file != NULL && !debug_flag) { 1878 FILE *f = fopen(options.pid_file, "w"); 1879 1880 if (f == NULL) { 1881 error("Couldn't create pid file \"%s\": %s", 1882 options.pid_file, strerror(errno)); 1883 } else { 1884 fprintf(f, "%ld\n", (long) getpid()); 1885 fclose(f); 1886 } 1887 } 1888 1889 /* Accept a connection and return in a forked child */ 1890 server_accept_loop(&sock_in, &sock_out, 1891 &newsock, config_s); 1892 } 1893 1894 /* This is the child processing a new connection. */ 1895 setproctitle("%s", "[accepted]"); 1896 1897 /* 1898 * Create a new session and process group since the 4.4BSD 1899 * setlogin() affects the entire process group. We don't 1900 * want the child to be able to affect the parent. 1901 */ 1902 #if !defined(SSHD_ACQUIRES_CTTY) 1903 /* 1904 * If setsid is called, on some platforms sshd will later acquire a 1905 * controlling terminal which will result in "could not set 1906 * controlling tty" errors. 1907 */ 1908 if (!debug_flag && !inetd_flag && setsid() < 0) 1909 error("setsid: %.100s", strerror(errno)); 1910 #endif 1911 1912 if (rexec_flag) { 1913 int fd; 1914 1915 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1916 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1917 dup2(newsock, STDIN_FILENO); 1918 dup2(STDIN_FILENO, STDOUT_FILENO); 1919 if (startup_pipe == -1) 1920 close(REEXEC_STARTUP_PIPE_FD); 1921 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1922 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1923 close(startup_pipe); 1924 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1925 } 1926 1927 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1928 close(config_s[1]); 1929 1930 execv(rexec_argv[0], rexec_argv); 1931 1932 /* Reexec has failed, fall back and continue */ 1933 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1934 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1935 log_init(__progname, options.log_level, 1936 options.log_facility, log_stderr); 1937 1938 /* Clean up fds */ 1939 close(REEXEC_CONFIG_PASS_FD); 1940 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1941 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1942 dup2(fd, STDIN_FILENO); 1943 dup2(fd, STDOUT_FILENO); 1944 if (fd > STDERR_FILENO) 1945 close(fd); 1946 } 1947 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1948 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1949 } 1950 1951 /* Executed child processes don't need these. */ 1952 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1953 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1954 1955 /* 1956 * Disable the key regeneration alarm. We will not regenerate the 1957 * key since we are no longer in a position to give it to anyone. We 1958 * will not restart on SIGHUP since it no longer makes sense. 1959 */ 1960 alarm(0); 1961 signal(SIGALRM, SIG_DFL); 1962 signal(SIGHUP, SIG_DFL); 1963 signal(SIGTERM, SIG_DFL); 1964 signal(SIGQUIT, SIG_DFL); 1965 signal(SIGCHLD, SIG_DFL); 1966 signal(SIGINT, SIG_DFL); 1967 1968 /* 1969 * Register our connection. This turns encryption off because we do 1970 * not have a key. 1971 */ 1972 packet_set_connection(sock_in, sock_out); 1973 packet_set_server(); 1974 ssh = active_state; /* XXX */ 1975 check_ip_options(ssh); 1976 1977 /* Set SO_KEEPALIVE if requested. */ 1978 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1979 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1980 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1981 1982 if ((remote_port = ssh_remote_port(ssh)) < 0) { 1983 debug("ssh_remote_port failed"); 1984 cleanup_exit(255); 1985 } 1986 1987 /* 1988 * The rest of the code depends on the fact that 1989 * ssh_remote_ipaddr() caches the remote ip, even if 1990 * the socket goes away. 1991 */ 1992 remote_ip = ssh_remote_ipaddr(ssh); 1993 1994 #ifdef SSH_AUDIT_EVENTS 1995 audit_connection_from(remote_ip, remote_port); 1996 #endif 1997 1998 /* Log the connection. */ 1999 laddr = get_local_ipaddr(sock_in); 2000 verbose("Connection from %s port %d on %s port %d", 2001 remote_ip, remote_port, laddr, ssh_local_port(ssh)); 2002 free(laddr); 2003 2004 /* 2005 * We don't want to listen forever unless the other side 2006 * successfully authenticates itself. So we set up an alarm which is 2007 * cleared after successful authentication. A limit of zero 2008 * indicates no limit. Note that we don't set the alarm in debugging 2009 * mode; it is just annoying to have the server exit just when you 2010 * are about to discover the bug. 2011 */ 2012 signal(SIGALRM, grace_alarm_handler); 2013 if (!debug_flag) 2014 alarm(options.login_grace_time); 2015 2016 sshd_exchange_identification(ssh, sock_in, sock_out); 2017 packet_set_nonblocking(); 2018 2019 /* allocate authentication context */ 2020 authctxt = xcalloc(1, sizeof(*authctxt)); 2021 2022 authctxt->loginmsg = &loginmsg; 2023 2024 /* XXX global for cleanup, access from other modules */ 2025 the_authctxt = authctxt; 2026 2027 /* prepare buffer to collect messages to display to user after login */ 2028 buffer_init(&loginmsg); 2029 auth_debug_reset(); 2030 2031 if (use_privsep) { 2032 if (privsep_preauth(authctxt) == 1) 2033 goto authenticated; 2034 } else if (have_agent) { 2035 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2036 error("Unable to get agent socket: %s", ssh_err(r)); 2037 have_agent = 0; 2038 } 2039 } 2040 2041 /* perform the key exchange */ 2042 /* authenticate user and start session */ 2043 do_ssh2_kex(); 2044 do_authentication2(authctxt); 2045 2046 /* 2047 * If we use privilege separation, the unprivileged child transfers 2048 * the current keystate and exits 2049 */ 2050 if (use_privsep) { 2051 mm_send_keystate(pmonitor); 2052 exit(0); 2053 } 2054 2055 authenticated: 2056 /* 2057 * Cancel the alarm we set to limit the time taken for 2058 * authentication. 2059 */ 2060 alarm(0); 2061 signal(SIGALRM, SIG_DFL); 2062 authctxt->authenticated = 1; 2063 if (startup_pipe != -1) { 2064 close(startup_pipe); 2065 startup_pipe = -1; 2066 } 2067 2068 #ifdef SSH_AUDIT_EVENTS 2069 audit_event(SSH_AUTH_SUCCESS); 2070 #endif 2071 2072 #ifdef GSSAPI 2073 if (options.gss_authentication) { 2074 temporarily_use_uid(authctxt->pw); 2075 ssh_gssapi_storecreds(); 2076 restore_uid(); 2077 } 2078 #endif 2079 #ifdef USE_PAM 2080 if (options.use_pam) { 2081 do_pam_setcred(1); 2082 do_pam_session(); 2083 } 2084 #endif 2085 2086 /* 2087 * In privilege separation, we fork another child and prepare 2088 * file descriptor passing. 2089 */ 2090 if (use_privsep) { 2091 privsep_postauth(authctxt); 2092 /* the monitor process [priv] will not return */ 2093 } 2094 2095 packet_set_timeout(options.client_alive_interval, 2096 options.client_alive_count_max); 2097 2098 /* Try to send all our hostkeys to the client */ 2099 notify_hostkeys(active_state); 2100 2101 /* Start session. */ 2102 do_authenticated(authctxt); 2103 2104 /* The connection has been terminated. */ 2105 packet_get_bytes(&ibytes, &obytes); 2106 verbose("Transferred: sent %llu, received %llu bytes", 2107 (unsigned long long)obytes, (unsigned long long)ibytes); 2108 2109 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2110 2111 #ifdef USE_PAM 2112 if (options.use_pam) 2113 finish_pam(); 2114 #endif /* USE_PAM */ 2115 2116 #ifdef SSH_AUDIT_EVENTS 2117 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2118 #endif 2119 2120 packet_close(); 2121 2122 if (use_privsep) 2123 mm_terminate(); 2124 2125 exit(0); 2126 } 2127 2128 int 2129 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, size_t *slen, 2130 const u_char *data, size_t dlen, const char *alg, u_int flag) 2131 { 2132 int r; 2133 u_int xxx_slen, xxx_dlen = dlen; 2134 2135 if (privkey) { 2136 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen, 2137 alg) < 0)) 2138 fatal("%s: key_sign failed", __func__); 2139 if (slen) 2140 *slen = xxx_slen; 2141 } else if (use_privsep) { 2142 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen, 2143 alg) < 0) 2144 fatal("%s: pubkey_sign failed", __func__); 2145 if (slen) 2146 *slen = xxx_slen; 2147 } else { 2148 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2149 data, dlen, alg, datafellows)) != 0) 2150 fatal("%s: ssh_agent_sign failed: %s", 2151 __func__, ssh_err(r)); 2152 } 2153 return 0; 2154 } 2155 2156 /* SSH2 key exchange */ 2157 static void 2158 do_ssh2_kex(void) 2159 { 2160 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2161 struct kex *kex; 2162 int r; 2163 2164 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2165 options.kex_algorithms); 2166 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2167 options.ciphers); 2168 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2169 options.ciphers); 2170 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2171 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2172 2173 if (options.compression == COMP_NONE) { 2174 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2175 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2176 } 2177 2178 if (options.rekey_limit || options.rekey_interval) 2179 packet_set_rekey_limits(options.rekey_limit, 2180 options.rekey_interval); 2181 2182 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2183 list_hostkey_types()); 2184 2185 /* start key exchange */ 2186 if ((r = kex_setup(active_state, myproposal)) != 0) 2187 fatal("kex_setup: %s", ssh_err(r)); 2188 kex = active_state->kex; 2189 #ifdef WITH_OPENSSL 2190 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2191 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2192 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2193 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2194 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2195 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2196 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2197 # ifdef OPENSSL_HAS_ECC 2198 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2199 # endif 2200 #endif 2201 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2202 kex->server = 1; 2203 kex->client_version_string=client_version_string; 2204 kex->server_version_string=server_version_string; 2205 kex->load_host_public_key=&get_hostkey_public_by_type; 2206 kex->load_host_private_key=&get_hostkey_private_by_type; 2207 kex->host_key_index=&get_hostkey_index; 2208 kex->sign = sshd_hostkey_sign; 2209 2210 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 2211 2212 session_id2 = kex->session_id; 2213 session_id2_len = kex->session_id_len; 2214 2215 #ifdef DEBUG_KEXDH 2216 /* send 1st encrypted/maced/compressed message */ 2217 packet_start(SSH2_MSG_IGNORE); 2218 packet_put_cstring("markus"); 2219 packet_send(); 2220 packet_write_wait(); 2221 #endif 2222 debug("KEX done"); 2223 } 2224 2225 /* server specific fatal cleanup */ 2226 void 2227 cleanup_exit(int i) 2228 { 2229 if (the_authctxt) { 2230 do_cleanup(the_authctxt); 2231 if (use_privsep && privsep_is_preauth && 2232 pmonitor != NULL && pmonitor->m_pid > 1) { 2233 debug("Killing privsep child %d", pmonitor->m_pid); 2234 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2235 errno != ESRCH) 2236 error("%s: kill(%d): %s", __func__, 2237 pmonitor->m_pid, strerror(errno)); 2238 } 2239 } 2240 #ifdef SSH_AUDIT_EVENTS 2241 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2242 if (!use_privsep || mm_is_monitor()) 2243 audit_event(SSH_CONNECTION_ABANDON); 2244 #endif 2245 _exit(i); 2246 } 2247