1 /* $OpenBSD: sshd.c,v 1.470 2016/05/24 04:43:45 dtucker Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 47 #include <sys/types.h> 48 #include <sys/ioctl.h> 49 #include <sys/socket.h> 50 #ifdef HAVE_SYS_STAT_H 51 # include <sys/stat.h> 52 #endif 53 #ifdef HAVE_SYS_TIME_H 54 # include <sys/time.h> 55 #endif 56 #include "openbsd-compat/sys-tree.h" 57 #include "openbsd-compat/sys-queue.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 #include <limits.h> 75 76 #ifdef WITH_OPENSSL 77 #include <openssl/dh.h> 78 #include <openssl/bn.h> 79 #include <openssl/rand.h> 80 #include "openbsd-compat/openssl-compat.h" 81 #endif 82 83 #ifdef HAVE_SECUREWARE 84 #include <sys/security.h> 85 #include <prot.h> 86 #endif 87 88 #include "xmalloc.h" 89 #include "ssh.h" 90 #include "ssh1.h" 91 #include "ssh2.h" 92 #include "rsa.h" 93 #include "sshpty.h" 94 #include "packet.h" 95 #include "log.h" 96 #include "buffer.h" 97 #include "misc.h" 98 #include "match.h" 99 #include "servconf.h" 100 #include "uidswap.h" 101 #include "compat.h" 102 #include "cipher.h" 103 #include "digest.h" 104 #include "key.h" 105 #include "kex.h" 106 #include "myproposal.h" 107 #include "authfile.h" 108 #include "pathnames.h" 109 #include "atomicio.h" 110 #include "canohost.h" 111 #include "hostfile.h" 112 #include "auth.h" 113 #include "authfd.h" 114 #include "msg.h" 115 #include "dispatch.h" 116 #include "channels.h" 117 #include "session.h" 118 #include "monitor_mm.h" 119 #include "monitor.h" 120 #ifdef GSSAPI 121 #include "ssh-gss.h" 122 #endif 123 #include "monitor_wrap.h" 124 #include "ssh-sandbox.h" 125 #include "version.h" 126 #include "ssherr.h" 127 128 #ifndef O_NOCTTY 129 #define O_NOCTTY 0 130 #endif 131 132 /* Re-exec fds */ 133 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 134 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 135 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 136 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 137 138 extern char *__progname; 139 140 /* Server configuration options. */ 141 ServerOptions options; 142 143 /* Name of the server configuration file. */ 144 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 145 146 /* 147 * Debug mode flag. This can be set on the command line. If debug 148 * mode is enabled, extra debugging output will be sent to the system 149 * log, the daemon will not go to background, and will exit after processing 150 * the first connection. 151 */ 152 int debug_flag = 0; 153 154 /* Flag indicating that the daemon should only test the configuration and keys. */ 155 int test_flag = 0; 156 157 /* Flag indicating that the daemon is being started from inetd. */ 158 int inetd_flag = 0; 159 160 /* Flag indicating that sshd should not detach and become a daemon. */ 161 int no_daemon_flag = 0; 162 163 /* debug goes to stderr unless inetd_flag is set */ 164 int log_stderr = 0; 165 166 /* Saved arguments to main(). */ 167 char **saved_argv; 168 int saved_argc; 169 170 /* re-exec */ 171 int rexeced_flag = 0; 172 int rexec_flag = 1; 173 int rexec_argc = 0; 174 char **rexec_argv; 175 176 /* 177 * The sockets that the server is listening; this is used in the SIGHUP 178 * signal handler. 179 */ 180 #define MAX_LISTEN_SOCKS 16 181 int listen_socks[MAX_LISTEN_SOCKS]; 182 int num_listen_socks = 0; 183 184 /* 185 * the client's version string, passed by sshd2 in compat mode. if != NULL, 186 * sshd will skip the version-number exchange 187 */ 188 char *client_version_string = NULL; 189 char *server_version_string = NULL; 190 191 /* Daemon's agent connection */ 192 int auth_sock = -1; 193 int have_agent = 0; 194 195 /* 196 * Any really sensitive data in the application is contained in this 197 * structure. The idea is that this structure could be locked into memory so 198 * that the pages do not get written into swap. However, there are some 199 * problems. The private key contains BIGNUMs, and we do not (in principle) 200 * have access to the internals of them, and locking just the structure is 201 * not very useful. Currently, memory locking is not implemented. 202 */ 203 struct { 204 Key *server_key; /* ephemeral server key */ 205 Key *ssh1_host_key; /* ssh1 host key */ 206 Key **host_keys; /* all private host keys */ 207 Key **host_pubkeys; /* all public host keys */ 208 Key **host_certificates; /* all public host certificates */ 209 int have_ssh1_key; 210 int have_ssh2_key; 211 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 212 } sensitive_data; 213 214 /* 215 * Flag indicating whether the RSA server key needs to be regenerated. 216 * Is set in the SIGALRM handler and cleared when the key is regenerated. 217 */ 218 static volatile sig_atomic_t key_do_regen = 0; 219 220 /* This is set to true when a signal is received. */ 221 static volatile sig_atomic_t received_sighup = 0; 222 static volatile sig_atomic_t received_sigterm = 0; 223 224 /* session identifier, used by RSA-auth */ 225 u_char session_id[16]; 226 227 /* same for ssh2 */ 228 u_char *session_id2 = NULL; 229 u_int session_id2_len = 0; 230 231 /* record remote hostname or ip */ 232 u_int utmp_len = HOST_NAME_MAX+1; 233 234 /* options.max_startup sized array of fd ints */ 235 int *startup_pipes = NULL; 236 int startup_pipe; /* in child */ 237 238 /* variables used for privilege separation */ 239 int use_privsep = -1; 240 struct monitor *pmonitor = NULL; 241 int privsep_is_preauth = 1; 242 243 /* global authentication context */ 244 Authctxt *the_authctxt = NULL; 245 246 /* sshd_config buffer */ 247 Buffer cfg; 248 249 /* message to be displayed after login */ 250 Buffer loginmsg; 251 252 /* Unprivileged user */ 253 struct passwd *privsep_pw = NULL; 254 255 /* Prototypes for various functions defined later in this file. */ 256 void destroy_sensitive_data(void); 257 void demote_sensitive_data(void); 258 259 #ifdef WITH_SSH1 260 static void do_ssh1_kex(void); 261 #endif 262 static void do_ssh2_kex(void); 263 264 /* 265 * Close all listening sockets 266 */ 267 static void 268 close_listen_socks(void) 269 { 270 int i; 271 272 for (i = 0; i < num_listen_socks; i++) 273 close(listen_socks[i]); 274 num_listen_socks = -1; 275 } 276 277 static void 278 close_startup_pipes(void) 279 { 280 int i; 281 282 if (startup_pipes) 283 for (i = 0; i < options.max_startups; i++) 284 if (startup_pipes[i] != -1) 285 close(startup_pipes[i]); 286 } 287 288 /* 289 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 290 * the effect is to reread the configuration file (and to regenerate 291 * the server key). 292 */ 293 294 /*ARGSUSED*/ 295 static void 296 sighup_handler(int sig) 297 { 298 int save_errno = errno; 299 300 received_sighup = 1; 301 signal(SIGHUP, sighup_handler); 302 errno = save_errno; 303 } 304 305 /* 306 * Called from the main program after receiving SIGHUP. 307 * Restarts the server. 308 */ 309 static void 310 sighup_restart(void) 311 { 312 logit("Received SIGHUP; restarting."); 313 platform_pre_restart(); 314 close_listen_socks(); 315 close_startup_pipes(); 316 alarm(0); /* alarm timer persists across exec */ 317 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 318 execv(saved_argv[0], saved_argv); 319 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 320 strerror(errno)); 321 exit(1); 322 } 323 324 /* 325 * Generic signal handler for terminating signals in the master daemon. 326 */ 327 /*ARGSUSED*/ 328 static void 329 sigterm_handler(int sig) 330 { 331 received_sigterm = sig; 332 } 333 334 /* 335 * SIGCHLD handler. This is called whenever a child dies. This will then 336 * reap any zombies left by exited children. 337 */ 338 /*ARGSUSED*/ 339 static void 340 main_sigchld_handler(int sig) 341 { 342 int save_errno = errno; 343 pid_t pid; 344 int status; 345 346 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 347 (pid < 0 && errno == EINTR)) 348 ; 349 350 signal(SIGCHLD, main_sigchld_handler); 351 errno = save_errno; 352 } 353 354 /* 355 * Signal handler for the alarm after the login grace period has expired. 356 */ 357 /*ARGSUSED*/ 358 static void 359 grace_alarm_handler(int sig) 360 { 361 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 362 kill(pmonitor->m_pid, SIGALRM); 363 364 /* 365 * Try to kill any processes that we have spawned, E.g. authorized 366 * keys command helpers. 367 */ 368 if (getpgid(0) == getpid()) { 369 signal(SIGTERM, SIG_IGN); 370 kill(0, SIGTERM); 371 } 372 373 /* Log error and exit. */ 374 sigdie("Timeout before authentication for %s port %d", 375 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state)); 376 } 377 378 /* 379 * Signal handler for the key regeneration alarm. Note that this 380 * alarm only occurs in the daemon waiting for connections, and it does not 381 * do anything with the private key or random state before forking. 382 * Thus there should be no concurrency control/asynchronous execution 383 * problems. 384 */ 385 static void 386 generate_ephemeral_server_key(void) 387 { 388 verbose("Generating %s%d bit RSA key.", 389 sensitive_data.server_key ? "new " : "", options.server_key_bits); 390 if (sensitive_data.server_key != NULL) 391 key_free(sensitive_data.server_key); 392 sensitive_data.server_key = key_generate(KEY_RSA1, 393 options.server_key_bits); 394 verbose("RSA key generation complete."); 395 396 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 397 } 398 399 /*ARGSUSED*/ 400 static void 401 key_regeneration_alarm(int sig) 402 { 403 int save_errno = errno; 404 405 signal(SIGALRM, SIG_DFL); 406 errno = save_errno; 407 key_do_regen = 1; 408 } 409 410 static void 411 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) 412 { 413 u_int i; 414 int mismatch; 415 int remote_major, remote_minor; 416 int major, minor; 417 char *s, *newline = "\n"; 418 char buf[256]; /* Must not be larger than remote_version. */ 419 char remote_version[256]; /* Must be at least as big as buf. */ 420 421 if ((options.protocol & SSH_PROTO_1) && 422 (options.protocol & SSH_PROTO_2)) { 423 major = PROTOCOL_MAJOR_1; 424 minor = 99; 425 } else if (options.protocol & SSH_PROTO_2) { 426 major = PROTOCOL_MAJOR_2; 427 minor = PROTOCOL_MINOR_2; 428 newline = "\r\n"; 429 } else { 430 major = PROTOCOL_MAJOR_1; 431 minor = PROTOCOL_MINOR_1; 432 } 433 434 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 435 major, minor, SSH_VERSION, 436 *options.version_addendum == '\0' ? "" : " ", 437 options.version_addendum, newline); 438 439 /* Send our protocol version identification. */ 440 if (atomicio(vwrite, sock_out, server_version_string, 441 strlen(server_version_string)) 442 != strlen(server_version_string)) { 443 logit("Could not write ident string to %s port %d", 444 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 445 cleanup_exit(255); 446 } 447 448 /* Read other sides version identification. */ 449 memset(buf, 0, sizeof(buf)); 450 for (i = 0; i < sizeof(buf) - 1; i++) { 451 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 452 logit("Did not receive identification string " 453 "from %s port %d", 454 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 455 cleanup_exit(255); 456 } 457 if (buf[i] == '\r') { 458 buf[i] = 0; 459 /* Kludge for F-Secure Macintosh < 1.0.2 */ 460 if (i == 12 && 461 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 462 break; 463 continue; 464 } 465 if (buf[i] == '\n') { 466 buf[i] = 0; 467 break; 468 } 469 } 470 buf[sizeof(buf) - 1] = 0; 471 client_version_string = xstrdup(buf); 472 473 /* 474 * Check that the versions match. In future this might accept 475 * several versions and set appropriate flags to handle them. 476 * 477 * NOTE: unbounded string to remote_version, but limited size of 478 * buf prevents overflow. 479 */ 480 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 481 &remote_major, &remote_minor, remote_version) != 3) { 482 s = "Protocol mismatch.\n"; 483 (void) atomicio(vwrite, sock_out, s, strlen(s)); 484 logit("Bad protocol version identification '%.100s' " 485 "from %s port %d", client_version_string, 486 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 487 close(sock_in); 488 close(sock_out); 489 cleanup_exit(255); 490 } 491 debug("Client protocol version %d.%d; client software version %.100s", 492 remote_major, remote_minor, remote_version); 493 494 ssh->compat = compat_datafellows(remote_version); 495 496 if ((ssh->compat & SSH_BUG_PROBE) != 0) { 497 logit("probed from %s port %d with %s. Don't panic.", 498 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 499 client_version_string); 500 cleanup_exit(255); 501 } 502 if ((ssh->compat & SSH_BUG_SCANNER) != 0) { 503 logit("scanned from %s port %d with %s. Don't panic.", 504 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 505 client_version_string); 506 cleanup_exit(255); 507 } 508 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 509 logit("Client version \"%.100s\" uses unsafe RSA signature " 510 "scheme; disabling use of RSA keys", remote_version); 511 } 512 if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) { 513 fatal("Client version \"%.100s\" uses unsafe key agreement; " 514 "refusing connection", remote_version); 515 } 516 517 mismatch = 0; 518 switch (remote_major) { 519 case 1: 520 if (remote_minor == 99) { 521 if (options.protocol & SSH_PROTO_2) 522 enable_compat20(); 523 else 524 mismatch = 1; 525 break; 526 } 527 if (!(options.protocol & SSH_PROTO_1)) { 528 mismatch = 1; 529 break; 530 } 531 if (remote_minor < 3) { 532 packet_disconnect("Your ssh version is too old and " 533 "is no longer supported. Please install a newer version."); 534 } else if (remote_minor == 3) { 535 /* note that this disables agent-forwarding */ 536 enable_compat13(); 537 } 538 break; 539 case 2: 540 if (options.protocol & SSH_PROTO_2) { 541 enable_compat20(); 542 break; 543 } 544 /* FALLTHROUGH */ 545 default: 546 mismatch = 1; 547 break; 548 } 549 chop(server_version_string); 550 debug("Local version string %.200s", server_version_string); 551 552 if (mismatch) { 553 s = "Protocol major versions differ.\n"; 554 (void) atomicio(vwrite, sock_out, s, strlen(s)); 555 close(sock_in); 556 close(sock_out); 557 logit("Protocol major versions differ for %s port %d: " 558 "%.200s vs. %.200s", 559 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 560 server_version_string, client_version_string); 561 cleanup_exit(255); 562 } 563 } 564 565 /* Destroy the host and server keys. They will no longer be needed. */ 566 void 567 destroy_sensitive_data(void) 568 { 569 int i; 570 571 if (sensitive_data.server_key) { 572 key_free(sensitive_data.server_key); 573 sensitive_data.server_key = NULL; 574 } 575 for (i = 0; i < options.num_host_key_files; i++) { 576 if (sensitive_data.host_keys[i]) { 577 key_free(sensitive_data.host_keys[i]); 578 sensitive_data.host_keys[i] = NULL; 579 } 580 if (sensitive_data.host_certificates[i]) { 581 key_free(sensitive_data.host_certificates[i]); 582 sensitive_data.host_certificates[i] = NULL; 583 } 584 } 585 sensitive_data.ssh1_host_key = NULL; 586 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 587 } 588 589 /* Demote private to public keys for network child */ 590 void 591 demote_sensitive_data(void) 592 { 593 Key *tmp; 594 int i; 595 596 if (sensitive_data.server_key) { 597 tmp = key_demote(sensitive_data.server_key); 598 key_free(sensitive_data.server_key); 599 sensitive_data.server_key = tmp; 600 } 601 602 for (i = 0; i < options.num_host_key_files; i++) { 603 if (sensitive_data.host_keys[i]) { 604 tmp = key_demote(sensitive_data.host_keys[i]); 605 key_free(sensitive_data.host_keys[i]); 606 sensitive_data.host_keys[i] = tmp; 607 if (tmp->type == KEY_RSA1) 608 sensitive_data.ssh1_host_key = tmp; 609 } 610 /* Certs do not need demotion */ 611 } 612 613 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 614 } 615 616 static void 617 privsep_preauth_child(void) 618 { 619 u_int32_t rnd[256]; 620 gid_t gidset[1]; 621 622 /* Enable challenge-response authentication for privilege separation */ 623 privsep_challenge_enable(); 624 625 #ifdef GSSAPI 626 /* Cache supported mechanism OIDs for later use */ 627 if (options.gss_authentication) 628 ssh_gssapi_prepare_supported_oids(); 629 #endif 630 631 arc4random_stir(); 632 arc4random_buf(rnd, sizeof(rnd)); 633 #ifdef WITH_OPENSSL 634 RAND_seed(rnd, sizeof(rnd)); 635 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 636 fatal("%s: RAND_bytes failed", __func__); 637 #endif 638 explicit_bzero(rnd, sizeof(rnd)); 639 640 /* Demote the private keys to public keys. */ 641 demote_sensitive_data(); 642 643 /* Demote the child */ 644 if (getuid() == 0 || geteuid() == 0) { 645 /* Change our root directory */ 646 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 647 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 648 strerror(errno)); 649 if (chdir("/") == -1) 650 fatal("chdir(\"/\"): %s", strerror(errno)); 651 652 /* Drop our privileges */ 653 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 654 (u_int)privsep_pw->pw_gid); 655 gidset[0] = privsep_pw->pw_gid; 656 if (setgroups(1, gidset) < 0) 657 fatal("setgroups: %.100s", strerror(errno)); 658 permanently_set_uid(privsep_pw); 659 } 660 } 661 662 static int 663 privsep_preauth(Authctxt *authctxt) 664 { 665 int status, r; 666 pid_t pid; 667 struct ssh_sandbox *box = NULL; 668 669 /* Set up unprivileged child process to deal with network data */ 670 pmonitor = monitor_init(); 671 /* Store a pointer to the kex for later rekeying */ 672 pmonitor->m_pkex = &active_state->kex; 673 674 if (use_privsep == PRIVSEP_ON) 675 box = ssh_sandbox_init(pmonitor); 676 pid = fork(); 677 if (pid == -1) { 678 fatal("fork of unprivileged child failed"); 679 } else if (pid != 0) { 680 debug2("Network child is on pid %ld", (long)pid); 681 682 pmonitor->m_pid = pid; 683 if (have_agent) { 684 r = ssh_get_authentication_socket(&auth_sock); 685 if (r != 0) { 686 error("Could not get agent socket: %s", 687 ssh_err(r)); 688 have_agent = 0; 689 } 690 } 691 if (box != NULL) 692 ssh_sandbox_parent_preauth(box, pid); 693 monitor_child_preauth(authctxt, pmonitor); 694 695 /* Sync memory */ 696 monitor_sync(pmonitor); 697 698 /* Wait for the child's exit status */ 699 while (waitpid(pid, &status, 0) < 0) { 700 if (errno == EINTR) 701 continue; 702 pmonitor->m_pid = -1; 703 fatal("%s: waitpid: %s", __func__, strerror(errno)); 704 } 705 privsep_is_preauth = 0; 706 pmonitor->m_pid = -1; 707 if (WIFEXITED(status)) { 708 if (WEXITSTATUS(status) != 0) 709 fatal("%s: preauth child exited with status %d", 710 __func__, WEXITSTATUS(status)); 711 } else if (WIFSIGNALED(status)) 712 fatal("%s: preauth child terminated by signal %d", 713 __func__, WTERMSIG(status)); 714 if (box != NULL) 715 ssh_sandbox_parent_finish(box); 716 return 1; 717 } else { 718 /* child */ 719 close(pmonitor->m_sendfd); 720 close(pmonitor->m_log_recvfd); 721 722 /* Arrange for logging to be sent to the monitor */ 723 set_log_handler(mm_log_handler, pmonitor); 724 725 privsep_preauth_child(); 726 setproctitle("%s", "[net]"); 727 if (box != NULL) 728 ssh_sandbox_child(box); 729 730 return 0; 731 } 732 } 733 734 static void 735 privsep_postauth(Authctxt *authctxt) 736 { 737 u_int32_t rnd[256]; 738 739 #ifdef DISABLE_FD_PASSING 740 if (1) { 741 #else 742 if (authctxt->pw->pw_uid == 0 || options.use_login) { 743 #endif 744 /* File descriptor passing is broken or root login */ 745 use_privsep = 0; 746 goto skip; 747 } 748 749 /* New socket pair */ 750 monitor_reinit(pmonitor); 751 752 pmonitor->m_pid = fork(); 753 if (pmonitor->m_pid == -1) 754 fatal("fork of unprivileged child failed"); 755 else if (pmonitor->m_pid != 0) { 756 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 757 buffer_clear(&loginmsg); 758 monitor_child_postauth(pmonitor); 759 760 /* NEVERREACHED */ 761 exit(0); 762 } 763 764 /* child */ 765 766 close(pmonitor->m_sendfd); 767 pmonitor->m_sendfd = -1; 768 769 /* Demote the private keys to public keys. */ 770 demote_sensitive_data(); 771 772 arc4random_stir(); 773 arc4random_buf(rnd, sizeof(rnd)); 774 #ifdef WITH_OPENSSL 775 RAND_seed(rnd, sizeof(rnd)); 776 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 777 fatal("%s: RAND_bytes failed", __func__); 778 #endif 779 explicit_bzero(rnd, sizeof(rnd)); 780 781 /* Drop privileges */ 782 do_setusercontext(authctxt->pw); 783 784 skip: 785 /* It is safe now to apply the key state */ 786 monitor_apply_keystate(pmonitor); 787 788 /* 789 * Tell the packet layer that authentication was successful, since 790 * this information is not part of the key state. 791 */ 792 packet_set_authenticated(); 793 } 794 795 static char * 796 list_hostkey_types(void) 797 { 798 Buffer b; 799 const char *p; 800 char *ret; 801 int i; 802 Key *key; 803 804 buffer_init(&b); 805 for (i = 0; i < options.num_host_key_files; i++) { 806 key = sensitive_data.host_keys[i]; 807 if (key == NULL) 808 key = sensitive_data.host_pubkeys[i]; 809 if (key == NULL || key->type == KEY_RSA1) 810 continue; 811 /* Check that the key is accepted in HostkeyAlgorithms */ 812 if (match_pattern_list(sshkey_ssh_name(key), 813 options.hostkeyalgorithms, 0) != 1) { 814 debug3("%s: %s key not permitted by HostkeyAlgorithms", 815 __func__, sshkey_ssh_name(key)); 816 continue; 817 } 818 switch (key->type) { 819 case KEY_RSA: 820 case KEY_DSA: 821 case KEY_ECDSA: 822 case KEY_ED25519: 823 if (buffer_len(&b) > 0) 824 buffer_append(&b, ",", 1); 825 p = key_ssh_name(key); 826 buffer_append(&b, p, strlen(p)); 827 828 /* for RSA we also support SHA2 signatures */ 829 if (key->type == KEY_RSA) { 830 p = ",rsa-sha2-512,rsa-sha2-256"; 831 buffer_append(&b, p, strlen(p)); 832 } 833 break; 834 } 835 /* If the private key has a cert peer, then list that too */ 836 key = sensitive_data.host_certificates[i]; 837 if (key == NULL) 838 continue; 839 switch (key->type) { 840 case KEY_RSA_CERT: 841 case KEY_DSA_CERT: 842 case KEY_ECDSA_CERT: 843 case KEY_ED25519_CERT: 844 if (buffer_len(&b) > 0) 845 buffer_append(&b, ",", 1); 846 p = key_ssh_name(key); 847 buffer_append(&b, p, strlen(p)); 848 break; 849 } 850 } 851 if ((ret = sshbuf_dup_string(&b)) == NULL) 852 fatal("%s: sshbuf_dup_string failed", __func__); 853 buffer_free(&b); 854 debug("list_hostkey_types: %s", ret); 855 return ret; 856 } 857 858 static Key * 859 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 860 { 861 int i; 862 Key *key; 863 864 for (i = 0; i < options.num_host_key_files; i++) { 865 switch (type) { 866 case KEY_RSA_CERT: 867 case KEY_DSA_CERT: 868 case KEY_ECDSA_CERT: 869 case KEY_ED25519_CERT: 870 key = sensitive_data.host_certificates[i]; 871 break; 872 default: 873 key = sensitive_data.host_keys[i]; 874 if (key == NULL && !need_private) 875 key = sensitive_data.host_pubkeys[i]; 876 break; 877 } 878 if (key != NULL && key->type == type && 879 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 880 return need_private ? 881 sensitive_data.host_keys[i] : key; 882 } 883 return NULL; 884 } 885 886 Key * 887 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 888 { 889 return get_hostkey_by_type(type, nid, 0, ssh); 890 } 891 892 Key * 893 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 894 { 895 return get_hostkey_by_type(type, nid, 1, ssh); 896 } 897 898 Key * 899 get_hostkey_by_index(int ind) 900 { 901 if (ind < 0 || ind >= options.num_host_key_files) 902 return (NULL); 903 return (sensitive_data.host_keys[ind]); 904 } 905 906 Key * 907 get_hostkey_public_by_index(int ind, struct ssh *ssh) 908 { 909 if (ind < 0 || ind >= options.num_host_key_files) 910 return (NULL); 911 return (sensitive_data.host_pubkeys[ind]); 912 } 913 914 int 915 get_hostkey_index(Key *key, int compare, struct ssh *ssh) 916 { 917 int i; 918 919 for (i = 0; i < options.num_host_key_files; i++) { 920 if (key_is_cert(key)) { 921 if (key == sensitive_data.host_certificates[i] || 922 (compare && sensitive_data.host_certificates[i] && 923 sshkey_equal(key, 924 sensitive_data.host_certificates[i]))) 925 return (i); 926 } else { 927 if (key == sensitive_data.host_keys[i] || 928 (compare && sensitive_data.host_keys[i] && 929 sshkey_equal(key, sensitive_data.host_keys[i]))) 930 return (i); 931 if (key == sensitive_data.host_pubkeys[i] || 932 (compare && sensitive_data.host_pubkeys[i] && 933 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 934 return (i); 935 } 936 } 937 return (-1); 938 } 939 940 /* Inform the client of all hostkeys */ 941 static void 942 notify_hostkeys(struct ssh *ssh) 943 { 944 struct sshbuf *buf; 945 struct sshkey *key; 946 int i, nkeys, r; 947 char *fp; 948 949 /* Some clients cannot cope with the hostkeys message, skip those. */ 950 if (datafellows & SSH_BUG_HOSTKEYS) 951 return; 952 953 if ((buf = sshbuf_new()) == NULL) 954 fatal("%s: sshbuf_new", __func__); 955 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 956 key = get_hostkey_public_by_index(i, ssh); 957 if (key == NULL || key->type == KEY_UNSPEC || 958 key->type == KEY_RSA1 || sshkey_is_cert(key)) 959 continue; 960 fp = sshkey_fingerprint(key, options.fingerprint_hash, 961 SSH_FP_DEFAULT); 962 debug3("%s: key %d: %s %s", __func__, i, 963 sshkey_ssh_name(key), fp); 964 free(fp); 965 if (nkeys == 0) { 966 packet_start(SSH2_MSG_GLOBAL_REQUEST); 967 packet_put_cstring("hostkeys-00@openssh.com"); 968 packet_put_char(0); /* want-reply */ 969 } 970 sshbuf_reset(buf); 971 if ((r = sshkey_putb(key, buf)) != 0) 972 fatal("%s: couldn't put hostkey %d: %s", 973 __func__, i, ssh_err(r)); 974 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 975 nkeys++; 976 } 977 debug3("%s: sent %d hostkeys", __func__, nkeys); 978 if (nkeys == 0) 979 fatal("%s: no hostkeys", __func__); 980 packet_send(); 981 sshbuf_free(buf); 982 } 983 984 /* 985 * returns 1 if connection should be dropped, 0 otherwise. 986 * dropping starts at connection #max_startups_begin with a probability 987 * of (max_startups_rate/100). the probability increases linearly until 988 * all connections are dropped for startups > max_startups 989 */ 990 static int 991 drop_connection(int startups) 992 { 993 int p, r; 994 995 if (startups < options.max_startups_begin) 996 return 0; 997 if (startups >= options.max_startups) 998 return 1; 999 if (options.max_startups_rate == 100) 1000 return 1; 1001 1002 p = 100 - options.max_startups_rate; 1003 p *= startups - options.max_startups_begin; 1004 p /= options.max_startups - options.max_startups_begin; 1005 p += options.max_startups_rate; 1006 r = arc4random_uniform(100); 1007 1008 debug("drop_connection: p %d, r %d", p, r); 1009 return (r < p) ? 1 : 0; 1010 } 1011 1012 static void 1013 usage(void) 1014 { 1015 fprintf(stderr, "%s, %s\n", 1016 SSH_RELEASE, 1017 #ifdef WITH_OPENSSL 1018 SSLeay_version(SSLEAY_VERSION) 1019 #else 1020 "without OpenSSL" 1021 #endif 1022 ); 1023 fprintf(stderr, 1024 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 1025 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 1026 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 1027 " [-u len]\n" 1028 ); 1029 exit(1); 1030 } 1031 1032 static void 1033 send_rexec_state(int fd, struct sshbuf *conf) 1034 { 1035 struct sshbuf *m; 1036 int r; 1037 1038 debug3("%s: entering fd = %d config len %zu", __func__, fd, 1039 sshbuf_len(conf)); 1040 1041 /* 1042 * Protocol from reexec master to child: 1043 * string configuration 1044 * u_int ephemeral_key_follows 1045 * bignum e (only if ephemeral_key_follows == 1) 1046 * bignum n " 1047 * bignum d " 1048 * bignum iqmp " 1049 * bignum p " 1050 * bignum q " 1051 * string rngseed (only if OpenSSL is not self-seeded) 1052 */ 1053 if ((m = sshbuf_new()) == NULL) 1054 fatal("%s: sshbuf_new failed", __func__); 1055 if ((r = sshbuf_put_stringb(m, conf)) != 0) 1056 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1057 1058 #ifdef WITH_SSH1 1059 if (sensitive_data.server_key != NULL && 1060 sensitive_data.server_key->type == KEY_RSA1) { 1061 if ((r = sshbuf_put_u32(m, 1)) != 0 || 1062 (r = sshbuf_put_bignum1(m, 1063 sensitive_data.server_key->rsa->e)) != 0 || 1064 (r = sshbuf_put_bignum1(m, 1065 sensitive_data.server_key->rsa->n)) != 0 || 1066 (r = sshbuf_put_bignum1(m, 1067 sensitive_data.server_key->rsa->d)) != 0 || 1068 (r = sshbuf_put_bignum1(m, 1069 sensitive_data.server_key->rsa->iqmp)) != 0 || 1070 (r = sshbuf_put_bignum1(m, 1071 sensitive_data.server_key->rsa->p)) != 0 || 1072 (r = sshbuf_put_bignum1(m, 1073 sensitive_data.server_key->rsa->q)) != 0) 1074 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1075 } else 1076 #endif 1077 if ((r = sshbuf_put_u32(m, 1)) != 0) 1078 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1079 1080 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1081 rexec_send_rng_seed(m); 1082 #endif 1083 1084 if (ssh_msg_send(fd, 0, m) == -1) 1085 fatal("%s: ssh_msg_send failed", __func__); 1086 1087 sshbuf_free(m); 1088 1089 debug3("%s: done", __func__); 1090 } 1091 1092 static void 1093 recv_rexec_state(int fd, Buffer *conf) 1094 { 1095 Buffer m; 1096 char *cp; 1097 u_int len; 1098 1099 debug3("%s: entering fd = %d", __func__, fd); 1100 1101 buffer_init(&m); 1102 1103 if (ssh_msg_recv(fd, &m) == -1) 1104 fatal("%s: ssh_msg_recv failed", __func__); 1105 if (buffer_get_char(&m) != 0) 1106 fatal("%s: rexec version mismatch", __func__); 1107 1108 cp = buffer_get_string(&m, &len); 1109 if (conf != NULL) 1110 buffer_append(conf, cp, len); 1111 free(cp); 1112 1113 if (buffer_get_int(&m)) { 1114 #ifdef WITH_SSH1 1115 if (sensitive_data.server_key != NULL) 1116 key_free(sensitive_data.server_key); 1117 sensitive_data.server_key = key_new_private(KEY_RSA1); 1118 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1119 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1120 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1121 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1122 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1123 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1124 if (rsa_generate_additional_parameters( 1125 sensitive_data.server_key->rsa) != 0) 1126 fatal("%s: rsa_generate_additional_parameters " 1127 "error", __func__); 1128 #endif 1129 } 1130 1131 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1132 rexec_recv_rng_seed(&m); 1133 #endif 1134 1135 buffer_free(&m); 1136 1137 debug3("%s: done", __func__); 1138 } 1139 1140 /* Accept a connection from inetd */ 1141 static void 1142 server_accept_inetd(int *sock_in, int *sock_out) 1143 { 1144 int fd; 1145 1146 startup_pipe = -1; 1147 if (rexeced_flag) { 1148 close(REEXEC_CONFIG_PASS_FD); 1149 *sock_in = *sock_out = dup(STDIN_FILENO); 1150 if (!debug_flag) { 1151 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1152 close(REEXEC_STARTUP_PIPE_FD); 1153 } 1154 } else { 1155 *sock_in = dup(STDIN_FILENO); 1156 *sock_out = dup(STDOUT_FILENO); 1157 } 1158 /* 1159 * We intentionally do not close the descriptors 0, 1, and 2 1160 * as our code for setting the descriptors won't work if 1161 * ttyfd happens to be one of those. 1162 */ 1163 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1164 dup2(fd, STDIN_FILENO); 1165 dup2(fd, STDOUT_FILENO); 1166 if (!log_stderr) 1167 dup2(fd, STDERR_FILENO); 1168 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1169 close(fd); 1170 } 1171 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1172 } 1173 1174 /* 1175 * Listen for TCP connections 1176 */ 1177 static void 1178 server_listen(void) 1179 { 1180 int ret, listen_sock, on = 1; 1181 struct addrinfo *ai; 1182 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1183 1184 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1185 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1186 continue; 1187 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1188 fatal("Too many listen sockets. " 1189 "Enlarge MAX_LISTEN_SOCKS"); 1190 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1191 ntop, sizeof(ntop), strport, sizeof(strport), 1192 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1193 error("getnameinfo failed: %.100s", 1194 ssh_gai_strerror(ret)); 1195 continue; 1196 } 1197 /* Create socket for listening. */ 1198 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1199 ai->ai_protocol); 1200 if (listen_sock < 0) { 1201 /* kernel may not support ipv6 */ 1202 verbose("socket: %.100s", strerror(errno)); 1203 continue; 1204 } 1205 if (set_nonblock(listen_sock) == -1) { 1206 close(listen_sock); 1207 continue; 1208 } 1209 /* 1210 * Set socket options. 1211 * Allow local port reuse in TIME_WAIT. 1212 */ 1213 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1214 &on, sizeof(on)) == -1) 1215 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1216 1217 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1218 if (ai->ai_family == AF_INET6) 1219 sock_set_v6only(listen_sock); 1220 1221 debug("Bind to port %s on %s.", strport, ntop); 1222 1223 /* Bind the socket to the desired port. */ 1224 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1225 error("Bind to port %s on %s failed: %.200s.", 1226 strport, ntop, strerror(errno)); 1227 close(listen_sock); 1228 continue; 1229 } 1230 listen_socks[num_listen_socks] = listen_sock; 1231 num_listen_socks++; 1232 1233 /* Start listening on the port. */ 1234 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1235 fatal("listen on [%s]:%s: %.100s", 1236 ntop, strport, strerror(errno)); 1237 logit("Server listening on %s port %s.", ntop, strport); 1238 } 1239 freeaddrinfo(options.listen_addrs); 1240 1241 if (!num_listen_socks) 1242 fatal("Cannot bind any address."); 1243 } 1244 1245 /* 1246 * The main TCP accept loop. Note that, for the non-debug case, returns 1247 * from this function are in a forked subprocess. 1248 */ 1249 static void 1250 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1251 { 1252 fd_set *fdset; 1253 int i, j, ret, maxfd; 1254 int key_used = 0, startups = 0; 1255 int startup_p[2] = { -1 , -1 }; 1256 struct sockaddr_storage from; 1257 socklen_t fromlen; 1258 pid_t pid; 1259 u_char rnd[256]; 1260 1261 /* setup fd set for accept */ 1262 fdset = NULL; 1263 maxfd = 0; 1264 for (i = 0; i < num_listen_socks; i++) 1265 if (listen_socks[i] > maxfd) 1266 maxfd = listen_socks[i]; 1267 /* pipes connected to unauthenticated childs */ 1268 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1269 for (i = 0; i < options.max_startups; i++) 1270 startup_pipes[i] = -1; 1271 1272 /* 1273 * Stay listening for connections until the system crashes or 1274 * the daemon is killed with a signal. 1275 */ 1276 for (;;) { 1277 if (received_sighup) 1278 sighup_restart(); 1279 free(fdset); 1280 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1281 sizeof(fd_mask)); 1282 1283 for (i = 0; i < num_listen_socks; i++) 1284 FD_SET(listen_socks[i], fdset); 1285 for (i = 0; i < options.max_startups; i++) 1286 if (startup_pipes[i] != -1) 1287 FD_SET(startup_pipes[i], fdset); 1288 1289 /* Wait in select until there is a connection. */ 1290 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1291 if (ret < 0 && errno != EINTR) 1292 error("select: %.100s", strerror(errno)); 1293 if (received_sigterm) { 1294 logit("Received signal %d; terminating.", 1295 (int) received_sigterm); 1296 close_listen_socks(); 1297 if (options.pid_file != NULL) 1298 unlink(options.pid_file); 1299 exit(received_sigterm == SIGTERM ? 0 : 255); 1300 } 1301 if (key_used && key_do_regen) { 1302 generate_ephemeral_server_key(); 1303 key_used = 0; 1304 key_do_regen = 0; 1305 } 1306 if (ret < 0) 1307 continue; 1308 1309 for (i = 0; i < options.max_startups; i++) 1310 if (startup_pipes[i] != -1 && 1311 FD_ISSET(startup_pipes[i], fdset)) { 1312 /* 1313 * the read end of the pipe is ready 1314 * if the child has closed the pipe 1315 * after successful authentication 1316 * or if the child has died 1317 */ 1318 close(startup_pipes[i]); 1319 startup_pipes[i] = -1; 1320 startups--; 1321 } 1322 for (i = 0; i < num_listen_socks; i++) { 1323 if (!FD_ISSET(listen_socks[i], fdset)) 1324 continue; 1325 fromlen = sizeof(from); 1326 *newsock = accept(listen_socks[i], 1327 (struct sockaddr *)&from, &fromlen); 1328 if (*newsock < 0) { 1329 if (errno != EINTR && errno != EWOULDBLOCK && 1330 errno != ECONNABORTED && errno != EAGAIN) 1331 error("accept: %.100s", 1332 strerror(errno)); 1333 if (errno == EMFILE || errno == ENFILE) 1334 usleep(100 * 1000); 1335 continue; 1336 } 1337 if (unset_nonblock(*newsock) == -1) { 1338 close(*newsock); 1339 continue; 1340 } 1341 if (drop_connection(startups) == 1) { 1342 debug("drop connection #%d", startups); 1343 close(*newsock); 1344 continue; 1345 } 1346 if (pipe(startup_p) == -1) { 1347 close(*newsock); 1348 continue; 1349 } 1350 1351 if (rexec_flag && socketpair(AF_UNIX, 1352 SOCK_STREAM, 0, config_s) == -1) { 1353 error("reexec socketpair: %s", 1354 strerror(errno)); 1355 close(*newsock); 1356 close(startup_p[0]); 1357 close(startup_p[1]); 1358 continue; 1359 } 1360 1361 for (j = 0; j < options.max_startups; j++) 1362 if (startup_pipes[j] == -1) { 1363 startup_pipes[j] = startup_p[0]; 1364 if (maxfd < startup_p[0]) 1365 maxfd = startup_p[0]; 1366 startups++; 1367 break; 1368 } 1369 1370 /* 1371 * Got connection. Fork a child to handle it, unless 1372 * we are in debugging mode. 1373 */ 1374 if (debug_flag) { 1375 /* 1376 * In debugging mode. Close the listening 1377 * socket, and start processing the 1378 * connection without forking. 1379 */ 1380 debug("Server will not fork when running in debugging mode."); 1381 close_listen_socks(); 1382 *sock_in = *newsock; 1383 *sock_out = *newsock; 1384 close(startup_p[0]); 1385 close(startup_p[1]); 1386 startup_pipe = -1; 1387 pid = getpid(); 1388 if (rexec_flag) { 1389 send_rexec_state(config_s[0], 1390 &cfg); 1391 close(config_s[0]); 1392 } 1393 break; 1394 } 1395 1396 /* 1397 * Normal production daemon. Fork, and have 1398 * the child process the connection. The 1399 * parent continues listening. 1400 */ 1401 platform_pre_fork(); 1402 if ((pid = fork()) == 0) { 1403 /* 1404 * Child. Close the listening and 1405 * max_startup sockets. Start using 1406 * the accepted socket. Reinitialize 1407 * logging (since our pid has changed). 1408 * We break out of the loop to handle 1409 * the connection. 1410 */ 1411 platform_post_fork_child(); 1412 startup_pipe = startup_p[1]; 1413 close_startup_pipes(); 1414 close_listen_socks(); 1415 *sock_in = *newsock; 1416 *sock_out = *newsock; 1417 log_init(__progname, 1418 options.log_level, 1419 options.log_facility, 1420 log_stderr); 1421 if (rexec_flag) 1422 close(config_s[0]); 1423 break; 1424 } 1425 1426 /* Parent. Stay in the loop. */ 1427 platform_post_fork_parent(pid); 1428 if (pid < 0) 1429 error("fork: %.100s", strerror(errno)); 1430 else 1431 debug("Forked child %ld.", (long)pid); 1432 1433 close(startup_p[1]); 1434 1435 if (rexec_flag) { 1436 send_rexec_state(config_s[0], &cfg); 1437 close(config_s[0]); 1438 close(config_s[1]); 1439 } 1440 1441 /* 1442 * Mark that the key has been used (it 1443 * was "given" to the child). 1444 */ 1445 if ((options.protocol & SSH_PROTO_1) && 1446 key_used == 0) { 1447 /* Schedule server key regeneration alarm. */ 1448 signal(SIGALRM, key_regeneration_alarm); 1449 alarm(options.key_regeneration_time); 1450 key_used = 1; 1451 } 1452 1453 close(*newsock); 1454 1455 /* 1456 * Ensure that our random state differs 1457 * from that of the child 1458 */ 1459 arc4random_stir(); 1460 arc4random_buf(rnd, sizeof(rnd)); 1461 #ifdef WITH_OPENSSL 1462 RAND_seed(rnd, sizeof(rnd)); 1463 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1464 fatal("%s: RAND_bytes failed", __func__); 1465 #endif 1466 explicit_bzero(rnd, sizeof(rnd)); 1467 } 1468 1469 /* child process check (or debug mode) */ 1470 if (num_listen_socks < 0) 1471 break; 1472 } 1473 } 1474 1475 /* 1476 * If IP options are supported, make sure there are none (log and 1477 * return an error if any are found). Basically we are worried about 1478 * source routing; it can be used to pretend you are somebody 1479 * (ip-address) you are not. That itself may be "almost acceptable" 1480 * under certain circumstances, but rhosts autentication is useless 1481 * if source routing is accepted. Notice also that if we just dropped 1482 * source routing here, the other side could use IP spoofing to do 1483 * rest of the interaction and could still bypass security. So we 1484 * exit here if we detect any IP options. 1485 */ 1486 static void 1487 check_ip_options(struct ssh *ssh) 1488 { 1489 #ifdef IP_OPTIONS 1490 int sock_in = ssh_packet_get_connection_in(ssh); 1491 struct sockaddr_storage from; 1492 socklen_t option_size, i, fromlen = sizeof(from); 1493 u_char opts[200]; 1494 char text[sizeof(opts) * 3 + 1]; 1495 1496 memset(&from, 0, sizeof(from)); 1497 if (getpeername(sock_in, (struct sockaddr *)&from, 1498 &fromlen) < 0) 1499 return; 1500 if (from.ss_family != AF_INET) 1501 return; 1502 /* XXX IPv6 options? */ 1503 1504 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1505 &option_size) >= 0 && option_size != 0) { 1506 text[0] = '\0'; 1507 for (i = 0; i < option_size; i++) 1508 snprintf(text + i*3, sizeof(text) - i*3, 1509 " %2.2x", opts[i]); 1510 fatal("Connection from %.100s port %d with IP opts: %.800s", 1511 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1512 } 1513 return; 1514 #endif /* IP_OPTIONS */ 1515 } 1516 1517 /* 1518 * Main program for the daemon. 1519 */ 1520 int 1521 main(int ac, char **av) 1522 { 1523 struct ssh *ssh = NULL; 1524 extern char *optarg; 1525 extern int optind; 1526 int r, opt, i, j, on = 1; 1527 int sock_in = -1, sock_out = -1, newsock = -1; 1528 const char *remote_ip; 1529 int remote_port; 1530 char *fp, *line, *laddr, *logfile = NULL; 1531 int config_s[2] = { -1 , -1 }; 1532 u_int n; 1533 u_int64_t ibytes, obytes; 1534 mode_t new_umask; 1535 Key *key; 1536 Key *pubkey; 1537 int keytype; 1538 Authctxt *authctxt; 1539 struct connection_info *connection_info = get_connection_info(0, 0); 1540 1541 ssh_malloc_init(); /* must be called before any mallocs */ 1542 1543 #ifdef HAVE_SECUREWARE 1544 (void)set_auth_parameters(ac, av); 1545 #endif 1546 __progname = ssh_get_progname(av[0]); 1547 1548 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1549 saved_argc = ac; 1550 rexec_argc = ac; 1551 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1552 for (i = 0; i < ac; i++) 1553 saved_argv[i] = xstrdup(av[i]); 1554 saved_argv[i] = NULL; 1555 1556 #ifndef HAVE_SETPROCTITLE 1557 /* Prepare for later setproctitle emulation */ 1558 compat_init_setproctitle(ac, av); 1559 av = saved_argv; 1560 #endif 1561 1562 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1563 debug("setgroups(): %.200s", strerror(errno)); 1564 1565 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1566 sanitise_stdfd(); 1567 1568 /* Initialize configuration options to their default values. */ 1569 initialize_server_options(&options); 1570 1571 /* Parse command-line arguments. */ 1572 while ((opt = getopt(ac, av, 1573 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1574 switch (opt) { 1575 case '4': 1576 options.address_family = AF_INET; 1577 break; 1578 case '6': 1579 options.address_family = AF_INET6; 1580 break; 1581 case 'f': 1582 config_file_name = optarg; 1583 break; 1584 case 'c': 1585 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1586 fprintf(stderr, "too many host certificates.\n"); 1587 exit(1); 1588 } 1589 options.host_cert_files[options.num_host_cert_files++] = 1590 derelativise_path(optarg); 1591 break; 1592 case 'd': 1593 if (debug_flag == 0) { 1594 debug_flag = 1; 1595 options.log_level = SYSLOG_LEVEL_DEBUG1; 1596 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1597 options.log_level++; 1598 break; 1599 case 'D': 1600 no_daemon_flag = 1; 1601 break; 1602 case 'E': 1603 logfile = optarg; 1604 /* FALLTHROUGH */ 1605 case 'e': 1606 log_stderr = 1; 1607 break; 1608 case 'i': 1609 inetd_flag = 1; 1610 break; 1611 case 'r': 1612 rexec_flag = 0; 1613 break; 1614 case 'R': 1615 rexeced_flag = 1; 1616 inetd_flag = 1; 1617 break; 1618 case 'Q': 1619 /* ignored */ 1620 break; 1621 case 'q': 1622 options.log_level = SYSLOG_LEVEL_QUIET; 1623 break; 1624 case 'b': 1625 options.server_key_bits = (int)strtonum(optarg, 256, 1626 32768, NULL); 1627 break; 1628 case 'p': 1629 options.ports_from_cmdline = 1; 1630 if (options.num_ports >= MAX_PORTS) { 1631 fprintf(stderr, "too many ports.\n"); 1632 exit(1); 1633 } 1634 options.ports[options.num_ports++] = a2port(optarg); 1635 if (options.ports[options.num_ports-1] <= 0) { 1636 fprintf(stderr, "Bad port number.\n"); 1637 exit(1); 1638 } 1639 break; 1640 case 'g': 1641 if ((options.login_grace_time = convtime(optarg)) == -1) { 1642 fprintf(stderr, "Invalid login grace time.\n"); 1643 exit(1); 1644 } 1645 break; 1646 case 'k': 1647 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1648 fprintf(stderr, "Invalid key regeneration interval.\n"); 1649 exit(1); 1650 } 1651 break; 1652 case 'h': 1653 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1654 fprintf(stderr, "too many host keys.\n"); 1655 exit(1); 1656 } 1657 options.host_key_files[options.num_host_key_files++] = 1658 derelativise_path(optarg); 1659 break; 1660 case 't': 1661 test_flag = 1; 1662 break; 1663 case 'T': 1664 test_flag = 2; 1665 break; 1666 case 'C': 1667 if (parse_server_match_testspec(connection_info, 1668 optarg) == -1) 1669 exit(1); 1670 break; 1671 case 'u': 1672 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1673 if (utmp_len > HOST_NAME_MAX+1) { 1674 fprintf(stderr, "Invalid utmp length.\n"); 1675 exit(1); 1676 } 1677 break; 1678 case 'o': 1679 line = xstrdup(optarg); 1680 if (process_server_config_line(&options, line, 1681 "command-line", 0, NULL, NULL) != 0) 1682 exit(1); 1683 free(line); 1684 break; 1685 case '?': 1686 default: 1687 usage(); 1688 break; 1689 } 1690 } 1691 if (rexeced_flag || inetd_flag) 1692 rexec_flag = 0; 1693 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1694 fatal("sshd re-exec requires execution with an absolute path"); 1695 if (rexeced_flag) 1696 closefrom(REEXEC_MIN_FREE_FD); 1697 else 1698 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1699 1700 #ifdef WITH_OPENSSL 1701 OpenSSL_add_all_algorithms(); 1702 #endif 1703 1704 /* If requested, redirect the logs to the specified logfile. */ 1705 if (logfile != NULL) 1706 log_redirect_stderr_to(logfile); 1707 /* 1708 * Force logging to stderr until we have loaded the private host 1709 * key (unless started from inetd) 1710 */ 1711 log_init(__progname, 1712 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1713 SYSLOG_LEVEL_INFO : options.log_level, 1714 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1715 SYSLOG_FACILITY_AUTH : options.log_facility, 1716 log_stderr || !inetd_flag); 1717 1718 /* 1719 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1720 * root's environment 1721 */ 1722 if (getenv("KRB5CCNAME") != NULL) 1723 (void) unsetenv("KRB5CCNAME"); 1724 1725 #ifdef _UNICOS 1726 /* Cray can define user privs drop all privs now! 1727 * Not needed on PRIV_SU systems! 1728 */ 1729 drop_cray_privs(); 1730 #endif 1731 1732 sensitive_data.server_key = NULL; 1733 sensitive_data.ssh1_host_key = NULL; 1734 sensitive_data.have_ssh1_key = 0; 1735 sensitive_data.have_ssh2_key = 0; 1736 1737 /* 1738 * If we're doing an extended config test, make sure we have all of 1739 * the parameters we need. If we're not doing an extended test, 1740 * do not silently ignore connection test params. 1741 */ 1742 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1743 fatal("user, host and addr are all required when testing " 1744 "Match configs"); 1745 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1746 fatal("Config test connection parameter (-C) provided without " 1747 "test mode (-T)"); 1748 1749 /* Fetch our configuration */ 1750 buffer_init(&cfg); 1751 if (rexeced_flag) 1752 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1753 else if (strcasecmp(config_file_name, "none") != 0) 1754 load_server_config(config_file_name, &cfg); 1755 1756 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1757 &cfg, NULL); 1758 1759 seed_rng(); 1760 1761 /* Fill in default values for those options not explicitly set. */ 1762 fill_default_server_options(&options); 1763 1764 /* challenge-response is implemented via keyboard interactive */ 1765 if (options.challenge_response_authentication) 1766 options.kbd_interactive_authentication = 1; 1767 1768 /* Check that options are sensible */ 1769 if (options.authorized_keys_command_user == NULL && 1770 (options.authorized_keys_command != NULL && 1771 strcasecmp(options.authorized_keys_command, "none") != 0)) 1772 fatal("AuthorizedKeysCommand set without " 1773 "AuthorizedKeysCommandUser"); 1774 if (options.authorized_principals_command_user == NULL && 1775 (options.authorized_principals_command != NULL && 1776 strcasecmp(options.authorized_principals_command, "none") != 0)) 1777 fatal("AuthorizedPrincipalsCommand set without " 1778 "AuthorizedPrincipalsCommandUser"); 1779 1780 /* 1781 * Check whether there is any path through configured auth methods. 1782 * Unfortunately it is not possible to verify this generally before 1783 * daemonisation in the presence of Match block, but this catches 1784 * and warns for trivial misconfigurations that could break login. 1785 */ 1786 if (options.num_auth_methods != 0) { 1787 if ((options.protocol & SSH_PROTO_1)) 1788 fatal("AuthenticationMethods is not supported with " 1789 "SSH protocol 1"); 1790 for (n = 0; n < options.num_auth_methods; n++) { 1791 if (auth2_methods_valid(options.auth_methods[n], 1792 1) == 0) 1793 break; 1794 } 1795 if (n >= options.num_auth_methods) 1796 fatal("AuthenticationMethods cannot be satisfied by " 1797 "enabled authentication methods"); 1798 } 1799 1800 /* set default channel AF */ 1801 channel_set_af(options.address_family); 1802 1803 /* Check that there are no remaining arguments. */ 1804 if (optind < ac) { 1805 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1806 exit(1); 1807 } 1808 1809 debug("sshd version %s, %s", SSH_VERSION, 1810 #ifdef WITH_OPENSSL 1811 SSLeay_version(SSLEAY_VERSION) 1812 #else 1813 "without OpenSSL" 1814 #endif 1815 ); 1816 1817 /* Store privilege separation user for later use if required. */ 1818 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1819 if (use_privsep || options.kerberos_authentication) 1820 fatal("Privilege separation user %s does not exist", 1821 SSH_PRIVSEP_USER); 1822 } else { 1823 explicit_bzero(privsep_pw->pw_passwd, 1824 strlen(privsep_pw->pw_passwd)); 1825 privsep_pw = pwcopy(privsep_pw); 1826 free(privsep_pw->pw_passwd); 1827 privsep_pw->pw_passwd = xstrdup("*"); 1828 } 1829 endpwent(); 1830 1831 /* load host keys */ 1832 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1833 sizeof(Key *)); 1834 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1835 sizeof(Key *)); 1836 1837 if (options.host_key_agent) { 1838 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1839 setenv(SSH_AUTHSOCKET_ENV_NAME, 1840 options.host_key_agent, 1); 1841 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1842 have_agent = 1; 1843 else 1844 error("Could not connect to agent \"%s\": %s", 1845 options.host_key_agent, ssh_err(r)); 1846 } 1847 1848 for (i = 0; i < options.num_host_key_files; i++) { 1849 if (options.host_key_files[i] == NULL) 1850 continue; 1851 key = key_load_private(options.host_key_files[i], "", NULL); 1852 pubkey = key_load_public(options.host_key_files[i], NULL); 1853 if (pubkey == NULL && key != NULL) 1854 pubkey = key_demote(key); 1855 sensitive_data.host_keys[i] = key; 1856 sensitive_data.host_pubkeys[i] = pubkey; 1857 1858 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1859 have_agent) { 1860 debug("will rely on agent for hostkey %s", 1861 options.host_key_files[i]); 1862 keytype = pubkey->type; 1863 } else if (key != NULL) { 1864 keytype = key->type; 1865 } else { 1866 error("Could not load host key: %s", 1867 options.host_key_files[i]); 1868 sensitive_data.host_keys[i] = NULL; 1869 sensitive_data.host_pubkeys[i] = NULL; 1870 continue; 1871 } 1872 1873 switch (keytype) { 1874 case KEY_RSA1: 1875 sensitive_data.ssh1_host_key = key; 1876 sensitive_data.have_ssh1_key = 1; 1877 break; 1878 case KEY_RSA: 1879 case KEY_DSA: 1880 case KEY_ECDSA: 1881 case KEY_ED25519: 1882 if (have_agent || key != NULL) 1883 sensitive_data.have_ssh2_key = 1; 1884 break; 1885 } 1886 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1887 SSH_FP_DEFAULT)) == NULL) 1888 fatal("sshkey_fingerprint failed"); 1889 debug("%s host key #%d: %s %s", 1890 key ? "private" : "agent", i, keytype == KEY_RSA1 ? 1891 sshkey_type(pubkey) : sshkey_ssh_name(pubkey), fp); 1892 free(fp); 1893 } 1894 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1895 logit("Disabling protocol version 1. Could not load host key"); 1896 options.protocol &= ~SSH_PROTO_1; 1897 } 1898 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1899 logit("Disabling protocol version 2. Could not load host key"); 1900 options.protocol &= ~SSH_PROTO_2; 1901 } 1902 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1903 logit("sshd: no hostkeys available -- exiting."); 1904 exit(1); 1905 } 1906 1907 /* 1908 * Load certificates. They are stored in an array at identical 1909 * indices to the public keys that they relate to. 1910 */ 1911 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1912 sizeof(Key *)); 1913 for (i = 0; i < options.num_host_key_files; i++) 1914 sensitive_data.host_certificates[i] = NULL; 1915 1916 for (i = 0; i < options.num_host_cert_files; i++) { 1917 if (options.host_cert_files[i] == NULL) 1918 continue; 1919 key = key_load_public(options.host_cert_files[i], NULL); 1920 if (key == NULL) { 1921 error("Could not load host certificate: %s", 1922 options.host_cert_files[i]); 1923 continue; 1924 } 1925 if (!key_is_cert(key)) { 1926 error("Certificate file is not a certificate: %s", 1927 options.host_cert_files[i]); 1928 key_free(key); 1929 continue; 1930 } 1931 /* Find matching private key */ 1932 for (j = 0; j < options.num_host_key_files; j++) { 1933 if (key_equal_public(key, 1934 sensitive_data.host_keys[j])) { 1935 sensitive_data.host_certificates[j] = key; 1936 break; 1937 } 1938 } 1939 if (j >= options.num_host_key_files) { 1940 error("No matching private key for certificate: %s", 1941 options.host_cert_files[i]); 1942 key_free(key); 1943 continue; 1944 } 1945 sensitive_data.host_certificates[j] = key; 1946 debug("host certificate: #%d type %d %s", j, key->type, 1947 key_type(key)); 1948 } 1949 1950 #ifdef WITH_SSH1 1951 /* Check certain values for sanity. */ 1952 if (options.protocol & SSH_PROTO_1) { 1953 if (options.server_key_bits < SSH_RSA_MINIMUM_MODULUS_SIZE || 1954 options.server_key_bits > OPENSSL_RSA_MAX_MODULUS_BITS) { 1955 fprintf(stderr, "Bad server key size.\n"); 1956 exit(1); 1957 } 1958 /* 1959 * Check that server and host key lengths differ sufficiently. This 1960 * is necessary to make double encryption work with rsaref. Oh, I 1961 * hate software patents. I dont know if this can go? Niels 1962 */ 1963 if (options.server_key_bits > 1964 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1965 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1966 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1967 SSH_KEY_BITS_RESERVED) { 1968 options.server_key_bits = 1969 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1970 SSH_KEY_BITS_RESERVED; 1971 debug("Forcing server key to %d bits to make it differ from host key.", 1972 options.server_key_bits); 1973 } 1974 } 1975 #endif 1976 1977 if (use_privsep) { 1978 struct stat st; 1979 1980 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1981 (S_ISDIR(st.st_mode) == 0)) 1982 fatal("Missing privilege separation directory: %s", 1983 _PATH_PRIVSEP_CHROOT_DIR); 1984 1985 #ifdef HAVE_CYGWIN 1986 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1987 (st.st_uid != getuid () || 1988 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1989 #else 1990 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1991 #endif 1992 fatal("%s must be owned by root and not group or " 1993 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1994 } 1995 1996 if (test_flag > 1) { 1997 if (server_match_spec_complete(connection_info) == 1) 1998 parse_server_match_config(&options, connection_info); 1999 dump_config(&options); 2000 } 2001 2002 /* Configuration looks good, so exit if in test mode. */ 2003 if (test_flag) 2004 exit(0); 2005 2006 /* 2007 * Clear out any supplemental groups we may have inherited. This 2008 * prevents inadvertent creation of files with bad modes (in the 2009 * portable version at least, it's certainly possible for PAM 2010 * to create a file, and we can't control the code in every 2011 * module which might be used). 2012 */ 2013 if (setgroups(0, NULL) < 0) 2014 debug("setgroups() failed: %.200s", strerror(errno)); 2015 2016 if (rexec_flag) { 2017 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 2018 for (i = 0; i < rexec_argc; i++) { 2019 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 2020 rexec_argv[i] = saved_argv[i]; 2021 } 2022 rexec_argv[rexec_argc] = "-R"; 2023 rexec_argv[rexec_argc + 1] = NULL; 2024 } 2025 2026 /* Ensure that umask disallows at least group and world write */ 2027 new_umask = umask(0077) | 0022; 2028 (void) umask(new_umask); 2029 2030 /* Initialize the log (it is reinitialized below in case we forked). */ 2031 if (debug_flag && (!inetd_flag || rexeced_flag)) 2032 log_stderr = 1; 2033 log_init(__progname, options.log_level, options.log_facility, log_stderr); 2034 2035 /* 2036 * If not in debugging mode, and not started from inetd, disconnect 2037 * from the controlling terminal, and fork. The original process 2038 * exits. 2039 */ 2040 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 2041 #ifdef TIOCNOTTY 2042 int fd; 2043 #endif /* TIOCNOTTY */ 2044 if (daemon(0, 0) < 0) 2045 fatal("daemon() failed: %.200s", strerror(errno)); 2046 2047 /* Disconnect from the controlling tty. */ 2048 #ifdef TIOCNOTTY 2049 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 2050 if (fd >= 0) { 2051 (void) ioctl(fd, TIOCNOTTY, NULL); 2052 close(fd); 2053 } 2054 #endif /* TIOCNOTTY */ 2055 } 2056 /* Reinitialize the log (because of the fork above). */ 2057 log_init(__progname, options.log_level, options.log_facility, log_stderr); 2058 2059 /* Chdir to the root directory so that the current disk can be 2060 unmounted if desired. */ 2061 if (chdir("/") == -1) 2062 error("chdir(\"/\"): %s", strerror(errno)); 2063 2064 /* ignore SIGPIPE */ 2065 signal(SIGPIPE, SIG_IGN); 2066 2067 /* Get a connection, either from inetd or a listening TCP socket */ 2068 if (inetd_flag) { 2069 server_accept_inetd(&sock_in, &sock_out); 2070 } else { 2071 platform_pre_listen(); 2072 server_listen(); 2073 2074 if (options.protocol & SSH_PROTO_1) 2075 generate_ephemeral_server_key(); 2076 2077 signal(SIGHUP, sighup_handler); 2078 signal(SIGCHLD, main_sigchld_handler); 2079 signal(SIGTERM, sigterm_handler); 2080 signal(SIGQUIT, sigterm_handler); 2081 2082 /* 2083 * Write out the pid file after the sigterm handler 2084 * is setup and the listen sockets are bound 2085 */ 2086 if (options.pid_file != NULL && !debug_flag) { 2087 FILE *f = fopen(options.pid_file, "w"); 2088 2089 if (f == NULL) { 2090 error("Couldn't create pid file \"%s\": %s", 2091 options.pid_file, strerror(errno)); 2092 } else { 2093 fprintf(f, "%ld\n", (long) getpid()); 2094 fclose(f); 2095 } 2096 } 2097 2098 /* Accept a connection and return in a forked child */ 2099 server_accept_loop(&sock_in, &sock_out, 2100 &newsock, config_s); 2101 } 2102 2103 /* This is the child processing a new connection. */ 2104 setproctitle("%s", "[accepted]"); 2105 2106 /* 2107 * Create a new session and process group since the 4.4BSD 2108 * setlogin() affects the entire process group. We don't 2109 * want the child to be able to affect the parent. 2110 */ 2111 #if !defined(SSHD_ACQUIRES_CTTY) 2112 /* 2113 * If setsid is called, on some platforms sshd will later acquire a 2114 * controlling terminal which will result in "could not set 2115 * controlling tty" errors. 2116 */ 2117 if (!debug_flag && !inetd_flag && setsid() < 0) 2118 error("setsid: %.100s", strerror(errno)); 2119 #endif 2120 2121 if (rexec_flag) { 2122 int fd; 2123 2124 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2125 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2126 dup2(newsock, STDIN_FILENO); 2127 dup2(STDIN_FILENO, STDOUT_FILENO); 2128 if (startup_pipe == -1) 2129 close(REEXEC_STARTUP_PIPE_FD); 2130 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2131 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2132 close(startup_pipe); 2133 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2134 } 2135 2136 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2137 close(config_s[1]); 2138 2139 execv(rexec_argv[0], rexec_argv); 2140 2141 /* Reexec has failed, fall back and continue */ 2142 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2143 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2144 log_init(__progname, options.log_level, 2145 options.log_facility, log_stderr); 2146 2147 /* Clean up fds */ 2148 close(REEXEC_CONFIG_PASS_FD); 2149 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2150 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2151 dup2(fd, STDIN_FILENO); 2152 dup2(fd, STDOUT_FILENO); 2153 if (fd > STDERR_FILENO) 2154 close(fd); 2155 } 2156 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2157 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2158 } 2159 2160 /* Executed child processes don't need these. */ 2161 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2162 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2163 2164 /* 2165 * Disable the key regeneration alarm. We will not regenerate the 2166 * key since we are no longer in a position to give it to anyone. We 2167 * will not restart on SIGHUP since it no longer makes sense. 2168 */ 2169 alarm(0); 2170 signal(SIGALRM, SIG_DFL); 2171 signal(SIGHUP, SIG_DFL); 2172 signal(SIGTERM, SIG_DFL); 2173 signal(SIGQUIT, SIG_DFL); 2174 signal(SIGCHLD, SIG_DFL); 2175 signal(SIGINT, SIG_DFL); 2176 2177 /* 2178 * Register our connection. This turns encryption off because we do 2179 * not have a key. 2180 */ 2181 packet_set_connection(sock_in, sock_out); 2182 packet_set_server(); 2183 ssh = active_state; /* XXX */ 2184 check_ip_options(ssh); 2185 2186 /* Set SO_KEEPALIVE if requested. */ 2187 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2188 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2189 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2190 2191 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2192 debug("ssh_remote_port failed"); 2193 cleanup_exit(255); 2194 } 2195 2196 /* 2197 * The rest of the code depends on the fact that 2198 * ssh_remote_ipaddr() caches the remote ip, even if 2199 * the socket goes away. 2200 */ 2201 remote_ip = ssh_remote_ipaddr(ssh); 2202 2203 #ifdef SSH_AUDIT_EVENTS 2204 audit_connection_from(remote_ip, remote_port); 2205 #endif 2206 2207 /* Log the connection. */ 2208 laddr = get_local_ipaddr(sock_in); 2209 verbose("Connection from %s port %d on %s port %d", 2210 remote_ip, remote_port, laddr, ssh_local_port(ssh)); 2211 free(laddr); 2212 2213 /* 2214 * We don't want to listen forever unless the other side 2215 * successfully authenticates itself. So we set up an alarm which is 2216 * cleared after successful authentication. A limit of zero 2217 * indicates no limit. Note that we don't set the alarm in debugging 2218 * mode; it is just annoying to have the server exit just when you 2219 * are about to discover the bug. 2220 */ 2221 signal(SIGALRM, grace_alarm_handler); 2222 if (!debug_flag) 2223 alarm(options.login_grace_time); 2224 2225 sshd_exchange_identification(ssh, sock_in, sock_out); 2226 2227 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2228 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2229 generate_ephemeral_server_key(); 2230 2231 packet_set_nonblocking(); 2232 2233 /* allocate authentication context */ 2234 authctxt = xcalloc(1, sizeof(*authctxt)); 2235 2236 authctxt->loginmsg = &loginmsg; 2237 2238 /* XXX global for cleanup, access from other modules */ 2239 the_authctxt = authctxt; 2240 2241 /* prepare buffer to collect messages to display to user after login */ 2242 buffer_init(&loginmsg); 2243 auth_debug_reset(); 2244 2245 if (use_privsep) { 2246 if (privsep_preauth(authctxt) == 1) 2247 goto authenticated; 2248 } else if (compat20 && have_agent) { 2249 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2250 error("Unable to get agent socket: %s", ssh_err(r)); 2251 have_agent = 0; 2252 } 2253 } 2254 2255 /* perform the key exchange */ 2256 /* authenticate user and start session */ 2257 if (compat20) { 2258 do_ssh2_kex(); 2259 do_authentication2(authctxt); 2260 } else { 2261 #ifdef WITH_SSH1 2262 do_ssh1_kex(); 2263 do_authentication(authctxt); 2264 #else 2265 fatal("ssh1 not supported"); 2266 #endif 2267 } 2268 /* 2269 * If we use privilege separation, the unprivileged child transfers 2270 * the current keystate and exits 2271 */ 2272 if (use_privsep) { 2273 mm_send_keystate(pmonitor); 2274 exit(0); 2275 } 2276 2277 authenticated: 2278 /* 2279 * Cancel the alarm we set to limit the time taken for 2280 * authentication. 2281 */ 2282 alarm(0); 2283 signal(SIGALRM, SIG_DFL); 2284 authctxt->authenticated = 1; 2285 if (startup_pipe != -1) { 2286 close(startup_pipe); 2287 startup_pipe = -1; 2288 } 2289 2290 #ifdef SSH_AUDIT_EVENTS 2291 audit_event(SSH_AUTH_SUCCESS); 2292 #endif 2293 2294 #ifdef GSSAPI 2295 if (options.gss_authentication) { 2296 temporarily_use_uid(authctxt->pw); 2297 ssh_gssapi_storecreds(); 2298 restore_uid(); 2299 } 2300 #endif 2301 #ifdef USE_PAM 2302 if (options.use_pam) { 2303 do_pam_setcred(1); 2304 do_pam_session(); 2305 } 2306 #endif 2307 2308 /* 2309 * In privilege separation, we fork another child and prepare 2310 * file descriptor passing. 2311 */ 2312 if (use_privsep) { 2313 privsep_postauth(authctxt); 2314 /* the monitor process [priv] will not return */ 2315 if (!compat20) 2316 destroy_sensitive_data(); 2317 } 2318 2319 packet_set_timeout(options.client_alive_interval, 2320 options.client_alive_count_max); 2321 2322 /* Try to send all our hostkeys to the client */ 2323 if (compat20) 2324 notify_hostkeys(active_state); 2325 2326 /* Start session. */ 2327 do_authenticated(authctxt); 2328 2329 /* The connection has been terminated. */ 2330 packet_get_bytes(&ibytes, &obytes); 2331 verbose("Transferred: sent %llu, received %llu bytes", 2332 (unsigned long long)obytes, (unsigned long long)ibytes); 2333 2334 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2335 2336 #ifdef USE_PAM 2337 if (options.use_pam) 2338 finish_pam(); 2339 #endif /* USE_PAM */ 2340 2341 #ifdef SSH_AUDIT_EVENTS 2342 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2343 #endif 2344 2345 packet_close(); 2346 2347 if (use_privsep) 2348 mm_terminate(); 2349 2350 exit(0); 2351 } 2352 2353 #ifdef WITH_SSH1 2354 /* 2355 * Decrypt session_key_int using our private server key and private host key 2356 * (key with larger modulus first). 2357 */ 2358 int 2359 ssh1_session_key(BIGNUM *session_key_int) 2360 { 2361 struct ssh *ssh = active_state; /* XXX */ 2362 int rsafail = 0; 2363 2364 if (BN_cmp(sensitive_data.server_key->rsa->n, 2365 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2366 /* Server key has bigger modulus. */ 2367 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2368 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2369 SSH_KEY_BITS_RESERVED) { 2370 fatal("do_connection: %s port %d: " 2371 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2372 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 2373 BN_num_bits(sensitive_data.server_key->rsa->n), 2374 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2375 SSH_KEY_BITS_RESERVED); 2376 } 2377 if (rsa_private_decrypt(session_key_int, session_key_int, 2378 sensitive_data.server_key->rsa) != 0) 2379 rsafail++; 2380 if (rsa_private_decrypt(session_key_int, session_key_int, 2381 sensitive_data.ssh1_host_key->rsa) != 0) 2382 rsafail++; 2383 } else { 2384 /* Host key has bigger modulus (or they are equal). */ 2385 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2386 BN_num_bits(sensitive_data.server_key->rsa->n) + 2387 SSH_KEY_BITS_RESERVED) { 2388 fatal("do_connection: %s port %d: " 2389 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2390 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 2391 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2392 BN_num_bits(sensitive_data.server_key->rsa->n), 2393 SSH_KEY_BITS_RESERVED); 2394 } 2395 if (rsa_private_decrypt(session_key_int, session_key_int, 2396 sensitive_data.ssh1_host_key->rsa) != 0) 2397 rsafail++; 2398 if (rsa_private_decrypt(session_key_int, session_key_int, 2399 sensitive_data.server_key->rsa) != 0) 2400 rsafail++; 2401 } 2402 return (rsafail); 2403 } 2404 2405 /* 2406 * SSH1 key exchange 2407 */ 2408 static void 2409 do_ssh1_kex(void) 2410 { 2411 struct ssh *ssh = active_state; /* XXX */ 2412 int i, len; 2413 int rsafail = 0; 2414 BIGNUM *session_key_int, *fake_key_int, *real_key_int; 2415 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2416 u_char fake_key_bytes[4096 / 8]; 2417 size_t fake_key_len; 2418 u_char cookie[8]; 2419 u_int cipher_type, auth_mask, protocol_flags; 2420 2421 /* 2422 * Generate check bytes that the client must send back in the user 2423 * packet in order for it to be accepted; this is used to defy ip 2424 * spoofing attacks. Note that this only works against somebody 2425 * doing IP spoofing from a remote machine; any machine on the local 2426 * network can still see outgoing packets and catch the random 2427 * cookie. This only affects rhosts authentication, and this is one 2428 * of the reasons why it is inherently insecure. 2429 */ 2430 arc4random_buf(cookie, sizeof(cookie)); 2431 2432 /* 2433 * Send our public key. We include in the packet 64 bits of random 2434 * data that must be matched in the reply in order to prevent IP 2435 * spoofing. 2436 */ 2437 packet_start(SSH_SMSG_PUBLIC_KEY); 2438 for (i = 0; i < 8; i++) 2439 packet_put_char(cookie[i]); 2440 2441 /* Store our public server RSA key. */ 2442 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2443 packet_put_bignum(sensitive_data.server_key->rsa->e); 2444 packet_put_bignum(sensitive_data.server_key->rsa->n); 2445 2446 /* Store our public host RSA key. */ 2447 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2448 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2449 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2450 2451 /* Put protocol flags. */ 2452 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2453 2454 /* Declare which ciphers we support. */ 2455 packet_put_int(cipher_mask_ssh1(0)); 2456 2457 /* Declare supported authentication types. */ 2458 auth_mask = 0; 2459 if (options.rhosts_rsa_authentication) 2460 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2461 if (options.rsa_authentication) 2462 auth_mask |= 1 << SSH_AUTH_RSA; 2463 if (options.challenge_response_authentication == 1) 2464 auth_mask |= 1 << SSH_AUTH_TIS; 2465 if (options.password_authentication) 2466 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2467 packet_put_int(auth_mask); 2468 2469 /* Send the packet and wait for it to be sent. */ 2470 packet_send(); 2471 packet_write_wait(); 2472 2473 debug("Sent %d bit server key and %d bit host key.", 2474 BN_num_bits(sensitive_data.server_key->rsa->n), 2475 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2476 2477 /* Read clients reply (cipher type and session key). */ 2478 packet_read_expect(SSH_CMSG_SESSION_KEY); 2479 2480 /* Get cipher type and check whether we accept this. */ 2481 cipher_type = packet_get_char(); 2482 2483 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2484 packet_disconnect("Warning: client selects unsupported cipher."); 2485 2486 /* Get check bytes from the packet. These must match those we 2487 sent earlier with the public key packet. */ 2488 for (i = 0; i < 8; i++) 2489 if (cookie[i] != packet_get_char()) 2490 packet_disconnect("IP Spoofing check bytes do not match."); 2491 2492 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2493 2494 /* Get the encrypted integer. */ 2495 if ((real_key_int = BN_new()) == NULL) 2496 fatal("do_ssh1_kex: BN_new failed"); 2497 packet_get_bignum(real_key_int); 2498 2499 protocol_flags = packet_get_int(); 2500 packet_set_protocol_flags(protocol_flags); 2501 packet_check_eom(); 2502 2503 /* Setup a fake key in case RSA decryption fails */ 2504 if ((fake_key_int = BN_new()) == NULL) 2505 fatal("do_ssh1_kex: BN_new failed"); 2506 fake_key_len = BN_num_bytes(real_key_int); 2507 if (fake_key_len > sizeof(fake_key_bytes)) 2508 fake_key_len = sizeof(fake_key_bytes); 2509 arc4random_buf(fake_key_bytes, fake_key_len); 2510 if (BN_bin2bn(fake_key_bytes, fake_key_len, fake_key_int) == NULL) 2511 fatal("do_ssh1_kex: BN_bin2bn failed"); 2512 2513 /* Decrypt real_key_int using host/server keys */ 2514 rsafail = PRIVSEP(ssh1_session_key(real_key_int)); 2515 /* If decryption failed, use the fake key. Else, the real key. */ 2516 if (rsafail) 2517 session_key_int = fake_key_int; 2518 else 2519 session_key_int = real_key_int; 2520 2521 /* 2522 * Extract session key from the decrypted integer. The key is in the 2523 * least significant 256 bits of the integer; the first byte of the 2524 * key is in the highest bits. 2525 */ 2526 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2527 len = BN_num_bytes(session_key_int); 2528 if (len < 0 || (u_int)len > sizeof(session_key)) { 2529 error("%s: bad session key len from %s port %d: " 2530 "session_key_int %d > sizeof(session_key) %lu", __func__, 2531 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 2532 len, (u_long)sizeof(session_key)); 2533 rsafail++; 2534 } else { 2535 explicit_bzero(session_key, sizeof(session_key)); 2536 BN_bn2bin(session_key_int, 2537 session_key + sizeof(session_key) - len); 2538 2539 derive_ssh1_session_id( 2540 sensitive_data.ssh1_host_key->rsa->n, 2541 sensitive_data.server_key->rsa->n, 2542 cookie, session_id); 2543 /* 2544 * Xor the first 16 bytes of the session key with the 2545 * session id. 2546 */ 2547 for (i = 0; i < 16; i++) 2548 session_key[i] ^= session_id[i]; 2549 } 2550 2551 /* Destroy the private and public keys. No longer. */ 2552 destroy_sensitive_data(); 2553 2554 if (use_privsep) 2555 mm_ssh1_session_id(session_id); 2556 2557 /* Destroy the decrypted integer. It is no longer needed. */ 2558 BN_clear_free(real_key_int); 2559 BN_clear_free(fake_key_int); 2560 2561 /* Set the session key. From this on all communications will be encrypted. */ 2562 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2563 2564 /* Destroy our copy of the session key. It is no longer needed. */ 2565 explicit_bzero(session_key, sizeof(session_key)); 2566 2567 debug("Received session key; encryption turned on."); 2568 2569 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2570 packet_start(SSH_SMSG_SUCCESS); 2571 packet_send(); 2572 packet_write_wait(); 2573 } 2574 #endif 2575 2576 int 2577 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, size_t *slen, 2578 const u_char *data, size_t dlen, const char *alg, u_int flag) 2579 { 2580 int r; 2581 u_int xxx_slen, xxx_dlen = dlen; 2582 2583 if (privkey) { 2584 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen, 2585 alg) < 0)) 2586 fatal("%s: key_sign failed", __func__); 2587 if (slen) 2588 *slen = xxx_slen; 2589 } else if (use_privsep) { 2590 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen, 2591 alg) < 0) 2592 fatal("%s: pubkey_sign failed", __func__); 2593 if (slen) 2594 *slen = xxx_slen; 2595 } else { 2596 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2597 data, dlen, alg, datafellows)) != 0) 2598 fatal("%s: ssh_agent_sign failed: %s", 2599 __func__, ssh_err(r)); 2600 } 2601 return 0; 2602 } 2603 2604 /* SSH2 key exchange */ 2605 static void 2606 do_ssh2_kex(void) 2607 { 2608 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2609 struct kex *kex; 2610 int r; 2611 2612 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2613 options.kex_algorithms); 2614 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2615 options.ciphers); 2616 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2617 options.ciphers); 2618 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2619 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2620 2621 if (options.compression == COMP_NONE) { 2622 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2623 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2624 } else if (options.compression == COMP_DELAYED) { 2625 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2626 myproposal[PROPOSAL_COMP_ALGS_STOC] = 2627 "none,zlib@openssh.com"; 2628 } 2629 2630 if (options.rekey_limit || options.rekey_interval) 2631 packet_set_rekey_limits(options.rekey_limit, 2632 (time_t)options.rekey_interval); 2633 2634 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2635 list_hostkey_types()); 2636 2637 /* start key exchange */ 2638 if ((r = kex_setup(active_state, myproposal)) != 0) 2639 fatal("kex_setup: %s", ssh_err(r)); 2640 kex = active_state->kex; 2641 #ifdef WITH_OPENSSL 2642 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2643 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2644 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2645 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2646 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2647 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2648 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2649 # ifdef OPENSSL_HAS_ECC 2650 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2651 # endif 2652 #endif 2653 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2654 kex->server = 1; 2655 kex->client_version_string=client_version_string; 2656 kex->server_version_string=server_version_string; 2657 kex->load_host_public_key=&get_hostkey_public_by_type; 2658 kex->load_host_private_key=&get_hostkey_private_by_type; 2659 kex->host_key_index=&get_hostkey_index; 2660 kex->sign = sshd_hostkey_sign; 2661 2662 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 2663 2664 session_id2 = kex->session_id; 2665 session_id2_len = kex->session_id_len; 2666 2667 #ifdef DEBUG_KEXDH 2668 /* send 1st encrypted/maced/compressed message */ 2669 packet_start(SSH2_MSG_IGNORE); 2670 packet_put_cstring("markus"); 2671 packet_send(); 2672 packet_write_wait(); 2673 #endif 2674 debug("KEX done"); 2675 } 2676 2677 /* server specific fatal cleanup */ 2678 void 2679 cleanup_exit(int i) 2680 { 2681 if (the_authctxt) { 2682 do_cleanup(the_authctxt); 2683 if (use_privsep && privsep_is_preauth && 2684 pmonitor != NULL && pmonitor->m_pid > 1) { 2685 debug("Killing privsep child %d", pmonitor->m_pid); 2686 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2687 errno != ESRCH) 2688 error("%s: kill(%d): %s", __func__, 2689 pmonitor->m_pid, strerror(errno)); 2690 } 2691 } 2692 #ifdef SSH_AUDIT_EVENTS 2693 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2694 if (!use_privsep || mm_is_monitor()) 2695 audit_event(SSH_CONNECTION_ABANDON); 2696 #endif 2697 _exit(i); 2698 } 2699