1 /* $NetBSD: sshd.c,v 1.13 2013/11/08 19:18:25 christos Exp $ */ 2 /* $OpenBSD: sshd.c,v 1.404 2013/07/19 07:37:48 markus Exp $ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * This program is the ssh daemon. It listens for connections from clients, 8 * and performs authentication, executes use commands or shell, and forwards 9 * information to/from the application to the user client over an encrypted 10 * connection. This can also handle forwarding of X11, TCP/IP, and 11 * authentication agent connections. 12 * 13 * As far as I am concerned, the code I have written for this software 14 * can be used freely for any purpose. Any derived versions of this 15 * software must be clearly marked as such, and if the derived work is 16 * incompatible with the protocol description in the RFC file, it must be 17 * called by a name other than "ssh" or "Secure Shell". 18 * 19 * SSH2 implementation: 20 * Privilege Separation: 21 * 22 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 23 * Copyright (c) 2002 Niels Provos. All rights reserved. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 34 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 35 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 36 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 37 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 38 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 39 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 40 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 41 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 42 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 43 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 44 */ 45 46 #include "includes.h" 47 __RCSID("$NetBSD: sshd.c,v 1.13 2013/11/08 19:18:25 christos Exp $"); 48 #include <sys/types.h> 49 #include <sys/param.h> 50 #include <sys/ioctl.h> 51 #include <sys/wait.h> 52 #include <sys/tree.h> 53 #include <sys/stat.h> 54 #include <sys/socket.h> 55 #include <sys/time.h> 56 #include <sys/queue.h> 57 58 #include <errno.h> 59 #include <fcntl.h> 60 #include <netdb.h> 61 #include <paths.h> 62 #include <pwd.h> 63 #include <signal.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <string.h> 67 #include <unistd.h> 68 69 #include <openssl/dh.h> 70 #include <openssl/bn.h> 71 #include <openssl/md5.h> 72 #include <openssl/rand.h> 73 74 #include "xmalloc.h" 75 #include "ssh.h" 76 #include "ssh1.h" 77 #include "ssh2.h" 78 #include "rsa.h" 79 #include "sshpty.h" 80 #include "packet.h" 81 #include "log.h" 82 #include "buffer.h" 83 #include "servconf.h" 84 #include "uidswap.h" 85 #include "compat.h" 86 #include "cipher.h" 87 #include "key.h" 88 #include "kex.h" 89 #include "dh.h" 90 #include "myproposal.h" 91 #include "authfile.h" 92 #include "pathnames.h" 93 #include "atomicio.h" 94 #include "canohost.h" 95 #include "hostfile.h" 96 #include "auth.h" 97 #include "authfd.h" 98 #include "misc.h" 99 #include "msg.h" 100 #include "dispatch.h" 101 #include "channels.h" 102 #include "session.h" 103 #include "monitor_mm.h" 104 #include "monitor.h" 105 #ifdef GSSAPI 106 #include "ssh-gss.h" 107 #endif 108 #include "monitor_wrap.h" 109 #include "roaming.h" 110 #include "ssh-sandbox.h" 111 #include "version.h" 112 #include "random.h" 113 114 #ifdef LIBWRAP 115 #include <tcpd.h> 116 #include <syslog.h> 117 int allow_severity = LOG_INFO; 118 int deny_severity = LOG_WARNING; 119 #endif /* LIBWRAP */ 120 121 #ifdef WITH_LDAP_PUBKEY 122 #include "ldapauth.h" 123 #endif 124 125 #ifndef O_NOCTTY 126 #define O_NOCTTY 0 127 #endif 128 129 /* Re-exec fds */ 130 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 131 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 132 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 133 #define REEXEC_DEVURANDOM_FD (STDERR_FILENO + 4) 134 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 5) 135 136 int urandom_fd = -1; 137 138 int myflag = 0; 139 140 141 extern char *__progname; 142 143 /* Server configuration options. */ 144 ServerOptions options; 145 146 /* Name of the server configuration file. */ 147 const char *config_file_name = _PATH_SERVER_CONFIG_FILE; 148 149 /* 150 * Debug mode flag. This can be set on the command line. If debug 151 * mode is enabled, extra debugging output will be sent to the system 152 * log, the daemon will not go to background, and will exit after processing 153 * the first connection. 154 */ 155 int debug_flag = 0; 156 157 /* Flag indicating that the daemon should only test the configuration and keys. */ 158 int test_flag = 0; 159 160 /* Flag indicating that the daemon is being started from inetd. */ 161 int inetd_flag = 0; 162 163 /* Flag indicating that sshd should not detach and become a daemon. */ 164 int no_daemon_flag = 0; 165 166 /* debug goes to stderr unless inetd_flag is set */ 167 int log_stderr = 0; 168 169 /* Saved arguments to main(). */ 170 char **saved_argv; 171 172 /* re-exec */ 173 int rexeced_flag = 0; 174 int rexec_flag = 1; 175 int rexec_argc = 0; 176 char **rexec_argv; 177 178 /* 179 * The sockets that the server is listening; this is used in the SIGHUP 180 * signal handler. 181 */ 182 #define MAX_LISTEN_SOCKS 16 183 int listen_socks[MAX_LISTEN_SOCKS]; 184 int num_listen_socks = 0; 185 186 /* 187 * the client's version string, passed by sshd2 in compat mode. if != NULL, 188 * sshd will skip the version-number exchange 189 */ 190 char *client_version_string = NULL; 191 char *server_version_string = NULL; 192 193 /* for rekeying XXX fixme */ 194 Kex *xxx_kex; 195 196 /* Daemon's agent connection */ 197 AuthenticationConnection *auth_conn = NULL; 198 int have_agent = 0; 199 200 /* 201 * Any really sensitive data in the application is contained in this 202 * structure. The idea is that this structure could be locked into memory so 203 * that the pages do not get written into swap. However, there are some 204 * problems. The private key contains BIGNUMs, and we do not (in principle) 205 * have access to the internals of them, and locking just the structure is 206 * not very useful. Currently, memory locking is not implemented. 207 */ 208 struct { 209 Key *server_key; /* ephemeral server key */ 210 Key *ssh1_host_key; /* ssh1 host key */ 211 Key **host_keys; /* all private host keys */ 212 Key **host_pubkeys; /* all public host keys */ 213 Key **host_certificates; /* all public host certificates */ 214 int have_ssh1_key; 215 int have_ssh2_key; 216 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 217 } sensitive_data; 218 219 /* 220 * Flag indicating whether the RSA server key needs to be regenerated. 221 * Is set in the SIGALRM handler and cleared when the key is regenerated. 222 */ 223 static volatile sig_atomic_t key_do_regen = 0; 224 225 /* This is set to true when a signal is received. */ 226 static volatile sig_atomic_t received_sighup = 0; 227 static volatile sig_atomic_t received_sigterm = 0; 228 229 /* session identifier, used by RSA-auth */ 230 u_char session_id[16]; 231 232 /* same for ssh2 */ 233 u_char *session_id2 = NULL; 234 u_int session_id2_len = 0; 235 236 /* record remote hostname or ip */ 237 u_int utmp_len = MAXHOSTNAMELEN; 238 239 /* options.max_startup sized array of fd ints */ 240 int *startup_pipes = NULL; 241 int startup_pipe; /* in child */ 242 243 /* variables used for privilege separation */ 244 int use_privsep = -1; 245 struct monitor *pmonitor = NULL; 246 int privsep_is_preauth = 1; 247 248 /* global authentication context */ 249 Authctxt *the_authctxt = NULL; 250 251 /* sshd_config buffer */ 252 Buffer cfg; 253 254 /* message to be displayed after login */ 255 Buffer loginmsg; 256 257 /* Prototypes for various functions defined later in this file. */ 258 void destroy_sensitive_data(void); 259 void demote_sensitive_data(void); 260 261 static void do_ssh1_kex(void); 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 __dead static void 310 sighup_restart(void) 311 { 312 logit("Received SIGHUP; restarting."); 313 close_listen_socks(); 314 close_startup_pipes(); 315 alarm(0); /* alarm timer persists across exec */ 316 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 317 execv(saved_argv[0], saved_argv); 318 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 319 strerror(errno)); 320 exit(1); 321 } 322 323 /* 324 * Generic signal handler for terminating signals in the master daemon. 325 */ 326 /*ARGSUSED*/ 327 static void 328 sigterm_handler(int sig) 329 { 330 received_sigterm = sig; 331 } 332 333 /* 334 * SIGCHLD handler. This is called whenever a child dies. This will then 335 * reap any zombies left by exited children. 336 */ 337 /*ARGSUSED*/ 338 static void 339 main_sigchld_handler(int sig) 340 { 341 int save_errno = errno; 342 pid_t pid; 343 int status; 344 345 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 346 (pid < 0 && errno == EINTR)) 347 ; 348 349 signal(SIGCHLD, main_sigchld_handler); 350 errno = save_errno; 351 } 352 353 /* 354 * Signal handler for the alarm after the login grace period has expired. 355 */ 356 /*ARGSUSED*/ 357 __dead static void 358 grace_alarm_handler(int sig) 359 { 360 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 361 kill(pmonitor->m_pid, SIGALRM); 362 363 /* 364 * Try to kill any processes that we have spawned, E.g. authorized 365 * keys command helpers. 366 */ 367 if (getpgid(0) == getpid()) { 368 signal(SIGTERM, SIG_IGN); 369 killpg(0, SIGTERM); 370 } 371 372 /* Log error and exit. */ 373 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 374 } 375 376 /* 377 * Signal handler for the key regeneration alarm. Note that this 378 * alarm only occurs in the daemon waiting for connections, and it does not 379 * do anything with the private key or random state before forking. 380 * Thus there should be no concurrency control/asynchronous execution 381 * problems. 382 */ 383 static void 384 generate_ephemeral_server_key(void) 385 { 386 verbose("Generating %s%d bit RSA key.", 387 sensitive_data.server_key ? "new " : "", options.server_key_bits); 388 if (sensitive_data.server_key != NULL) 389 key_free(sensitive_data.server_key); 390 sensitive_data.server_key = key_generate(KEY_RSA1, 391 options.server_key_bits); 392 verbose("RSA key generation complete."); 393 394 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 395 arc4random_stir(); 396 } 397 398 /*ARGSUSED*/ 399 static void 400 key_regeneration_alarm(int sig) 401 { 402 int save_errno = errno; 403 404 signal(SIGALRM, SIG_DFL); 405 errno = save_errno; 406 key_do_regen = 1; 407 } 408 409 static void 410 sshd_exchange_identification(int sock_in, int sock_out) 411 { 412 u_int i; 413 int mismatch; 414 int remote_major, remote_minor; 415 int major, minor; 416 char *s; 417 const char *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 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 434 major, minor, SSH_VERSION, 435 *options.version_addendum == '\0' ? "" : " ", 436 options.version_addendum, newline); 437 438 /* Send our protocol version identification. */ 439 if (roaming_atomicio(vwrite, sock_out, server_version_string, 440 strlen(server_version_string)) 441 != strlen(server_version_string)) { 442 logit("Could not write ident string to %s", get_remote_ipaddr()); 443 cleanup_exit(255); 444 } 445 446 /* Read other sides version identification. */ 447 memset(buf, 0, sizeof(buf)); 448 for (i = 0; i < sizeof(buf) - 1; i++) { 449 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 450 logit("Did not receive identification string from %s", 451 get_remote_ipaddr()); 452 cleanup_exit(255); 453 } 454 if (buf[i] == '\r') { 455 buf[i] = 0; 456 /* Kludge for F-Secure Macintosh < 1.0.2 */ 457 if (i == 12 && 458 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 459 break; 460 continue; 461 } 462 if (buf[i] == '\n') { 463 buf[i] = 0; 464 break; 465 } 466 } 467 buf[sizeof(buf) - 1] = 0; 468 client_version_string = xstrdup(buf); 469 470 /* 471 * Check that the versions match. In future this might accept 472 * several versions and set appropriate flags to handle them. 473 */ 474 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 475 &remote_major, &remote_minor, remote_version) != 3) { 476 s = __UNCONST("Protocol mismatch.\n"); 477 (void) atomicio(vwrite, sock_out, s, strlen(s)); 478 close(sock_in); 479 close(sock_out); 480 logit("Bad protocol version identification '%.100s' from %s", 481 client_version_string, get_remote_ipaddr()); 482 cleanup_exit(255); 483 } 484 debug("Client protocol version %d.%d; client software version %.100s", 485 remote_major, remote_minor, remote_version); 486 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s", 487 get_remote_ipaddr(), get_remote_port(), 488 remote_major, remote_minor, remote_version); 489 490 compat_datafellows(remote_version); 491 492 if (datafellows & SSH_BUG_PROBE) { 493 logit("probed from %s with %s. Don't panic.", 494 get_remote_ipaddr(), client_version_string); 495 cleanup_exit(255); 496 } 497 498 if (datafellows & SSH_BUG_SCANNER) { 499 logit("scanned from %s with %s. Don't panic.", 500 get_remote_ipaddr(), client_version_string); 501 cleanup_exit(255); 502 } 503 504 mismatch = 0; 505 switch (remote_major) { 506 case 1: 507 if (remote_minor == 99) { 508 if (options.protocol & SSH_PROTO_2) 509 enable_compat20(); 510 else 511 mismatch = 1; 512 break; 513 } 514 if (!(options.protocol & SSH_PROTO_1)) { 515 mismatch = 1; 516 break; 517 } 518 if (remote_minor < 3) { 519 packet_disconnect("Your ssh version is too old and " 520 "is no longer supported. Please install a newer version."); 521 } else if (remote_minor == 3) { 522 /* note that this disables agent-forwarding */ 523 enable_compat13(); 524 } 525 break; 526 case 2: 527 if (options.protocol & SSH_PROTO_2) { 528 enable_compat20(); 529 break; 530 } 531 /* FALLTHROUGH */ 532 default: 533 mismatch = 1; 534 break; 535 } 536 chop(server_version_string); 537 debug("Local version string %.200s", server_version_string); 538 539 if (mismatch) { 540 s = __UNCONST("Protocol major versions differ.\n"); 541 (void) atomicio(vwrite, sock_out, s, strlen(s)); 542 close(sock_in); 543 close(sock_out); 544 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 545 get_remote_ipaddr(), 546 server_version_string, client_version_string); 547 cleanup_exit(255); 548 } 549 } 550 551 /* Destroy the host and server keys. They will no longer be needed. */ 552 void 553 destroy_sensitive_data(void) 554 { 555 int i; 556 557 if (sensitive_data.server_key) { 558 key_free(sensitive_data.server_key); 559 sensitive_data.server_key = NULL; 560 } 561 for (i = 0; i < options.num_host_key_files; i++) { 562 if (sensitive_data.host_keys[i]) { 563 key_free(sensitive_data.host_keys[i]); 564 sensitive_data.host_keys[i] = NULL; 565 } 566 if (sensitive_data.host_certificates[i]) { 567 key_free(sensitive_data.host_certificates[i]); 568 sensitive_data.host_certificates[i] = NULL; 569 } 570 } 571 sensitive_data.ssh1_host_key = NULL; 572 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 573 } 574 575 /* Demote private to public keys for network child */ 576 void 577 demote_sensitive_data(void) 578 { 579 Key *tmp; 580 int i; 581 582 if (sensitive_data.server_key) { 583 tmp = key_demote(sensitive_data.server_key); 584 key_free(sensitive_data.server_key); 585 sensitive_data.server_key = tmp; 586 } 587 588 for (i = 0; i < options.num_host_key_files; i++) { 589 if (sensitive_data.host_keys[i]) { 590 tmp = key_demote(sensitive_data.host_keys[i]); 591 key_free(sensitive_data.host_keys[i]); 592 sensitive_data.host_keys[i] = tmp; 593 if (tmp->type == KEY_RSA1) 594 sensitive_data.ssh1_host_key = tmp; 595 } 596 /* Certs do not need demotion */ 597 } 598 599 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 600 } 601 602 static void 603 privsep_preauth_child(void) 604 { 605 u_int32_t rnd[32]; 606 gid_t gidset[1]; 607 struct passwd *pw; 608 609 /* Enable challenge-response authentication for privilege separation */ 610 privsep_challenge_enable(); 611 612 if (read(urandom_fd, rnd, sizeof(rnd)) != sizeof(rnd)) { 613 fatal("privsep_preauth_child: entropy read failed"); 614 } 615 RAND_seed(rnd, sizeof(rnd)); 616 617 arc4random_stir(); 618 619 /* Demote the private keys to public keys. */ 620 demote_sensitive_data(); 621 622 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 623 fatal("Privilege separation user %s does not exist", 624 SSH_PRIVSEP_USER); 625 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); 626 endpwent(); 627 628 /* Change our root directory */ 629 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 630 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 631 strerror(errno)); 632 if (chdir("/") == -1) 633 fatal("chdir(\"/\"): %s", strerror(errno)); 634 635 /* Drop our privileges */ 636 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 637 (u_int)pw->pw_gid); 638 #if 0 639 /* XXX not ready, too heavy after chroot */ 640 do_setusercontext(pw); 641 #else 642 gidset[0] = pw->pw_gid; 643 if (setgroups(1, gidset) < 0) 644 fatal("setgroups: %.100s", strerror(errno)); 645 permanently_set_uid(pw); 646 #endif 647 } 648 649 static int 650 privsep_preauth(Authctxt *authctxt) 651 { 652 int status; 653 pid_t pid; 654 struct ssh_sandbox *box = NULL; 655 656 /* Set up unprivileged child process to deal with network data */ 657 pmonitor = monitor_init(); 658 /* Store a pointer to the kex for later rekeying */ 659 pmonitor->m_pkex = &xxx_kex; 660 661 if (use_privsep == PRIVSEP_ON) 662 box = ssh_sandbox_init(); 663 pid = fork(); 664 if (pid == -1) { 665 fatal("fork of unprivileged child failed"); 666 } else if (pid != 0) { 667 debug2("Network child is on pid %ld", (long)pid); 668 669 pmonitor->m_pid = pid; 670 if (have_agent) 671 auth_conn = ssh_get_authentication_connection(); 672 if (box != NULL) 673 ssh_sandbox_parent_preauth(box, pid); 674 monitor_child_preauth(authctxt, pmonitor); 675 676 /* Sync memory */ 677 monitor_sync(pmonitor); 678 679 /* Wait for the child's exit status */ 680 while (waitpid(pid, &status, 0) < 0) { 681 if (errno == EINTR) 682 continue; 683 pmonitor->m_pid = -1; 684 fatal("%s: waitpid: %s", __func__, strerror(errno)); 685 } 686 privsep_is_preauth = 0; 687 pmonitor->m_pid = -1; 688 if (WIFEXITED(status)) { 689 if (WEXITSTATUS(status) != 0) 690 fatal("%s: preauth child exited with status %d", 691 __func__, WEXITSTATUS(status)); 692 } else if (WIFSIGNALED(status)) 693 fatal("%s: preauth child terminated by signal %d", 694 __func__, WTERMSIG(status)); 695 if (box != NULL) 696 ssh_sandbox_parent_finish(box); 697 return 1; 698 } else { 699 /* child */ 700 close(pmonitor->m_sendfd); 701 close(pmonitor->m_log_recvfd); 702 703 /* Arrange for logging to be sent to the monitor */ 704 set_log_handler(mm_log_handler, pmonitor); 705 706 /* Demote the child */ 707 if (getuid() == 0 || geteuid() == 0) 708 privsep_preauth_child(); 709 setproctitle("%s", "[net]"); 710 if (box != NULL) 711 ssh_sandbox_child(box); 712 713 return 0; 714 } 715 } 716 717 static void 718 privsep_postauth(Authctxt *authctxt) 719 { 720 u_int32_t rnd[32]; 721 722 if (authctxt->pw->pw_uid == 0 || options.use_login) { 723 /* File descriptor passing is broken or root login */ 724 use_privsep = 0; 725 goto skip; 726 } 727 728 /* New socket pair */ 729 monitor_reinit(pmonitor); 730 731 pmonitor->m_pid = fork(); 732 if (pmonitor->m_pid == -1) 733 fatal("fork of unprivileged child failed"); 734 else if (pmonitor->m_pid != 0) { 735 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 736 buffer_clear(&loginmsg); 737 monitor_child_postauth(pmonitor); 738 739 /* NEVERREACHED */ 740 exit(0); 741 } 742 743 /* child */ 744 745 close(pmonitor->m_sendfd); 746 pmonitor->m_sendfd = -1; 747 748 /* Demote the private keys to public keys. */ 749 demote_sensitive_data(); 750 751 if (read(urandom_fd, rnd, sizeof(rnd)) != sizeof(rnd)) { 752 fatal("privsep_postauth: entropy read failed"); 753 } 754 RAND_seed(rnd, sizeof(rnd)); 755 756 arc4random_stir(); 757 758 /* Drop privileges */ 759 do_setusercontext(authctxt->pw); 760 761 skip: 762 /* It is safe now to apply the key state */ 763 monitor_apply_keystate(pmonitor); 764 765 /* 766 * Tell the packet layer that authentication was successful, since 767 * this information is not part of the key state. 768 */ 769 packet_set_authenticated(); 770 } 771 772 static char * 773 list_hostkey_types(void) 774 { 775 Buffer b; 776 const char *p; 777 char *ret; 778 int i; 779 Key *key; 780 781 buffer_init(&b); 782 for (i = 0; i < options.num_host_key_files; i++) { 783 key = sensitive_data.host_keys[i]; 784 if (key == NULL) 785 key = sensitive_data.host_pubkeys[i]; 786 if (key == NULL) 787 continue; 788 switch (key->type) { 789 case KEY_RSA: 790 case KEY_DSA: 791 case KEY_ECDSA: 792 if (buffer_len(&b) > 0) 793 buffer_append(&b, ",", 1); 794 p = key_ssh_name(key); 795 buffer_append(&b, p, strlen(p)); 796 break; 797 } 798 /* If the private key has a cert peer, then list that too */ 799 key = sensitive_data.host_certificates[i]; 800 if (key == NULL) 801 continue; 802 switch (key->type) { 803 case KEY_RSA_CERT_V00: 804 case KEY_DSA_CERT_V00: 805 case KEY_RSA_CERT: 806 case KEY_DSA_CERT: 807 case KEY_ECDSA_CERT: 808 if (buffer_len(&b) > 0) 809 buffer_append(&b, ",", 1); 810 p = key_ssh_name(key); 811 buffer_append(&b, p, strlen(p)); 812 break; 813 } 814 } 815 buffer_append(&b, "\0", 1); 816 ret = xstrdup(buffer_ptr(&b)); 817 buffer_free(&b); 818 debug("list_hostkey_types: %s", ret); 819 return ret; 820 } 821 822 static Key * 823 get_hostkey_by_type(int type, int need_private) 824 { 825 int i; 826 Key *key; 827 828 for (i = 0; i < options.num_host_key_files; i++) { 829 switch (type) { 830 case KEY_RSA_CERT_V00: 831 case KEY_DSA_CERT_V00: 832 case KEY_RSA_CERT: 833 case KEY_DSA_CERT: 834 case KEY_ECDSA_CERT: 835 key = sensitive_data.host_certificates[i]; 836 break; 837 default: 838 key = sensitive_data.host_keys[i]; 839 if (key == NULL && !need_private) 840 key = sensitive_data.host_pubkeys[i]; 841 break; 842 } 843 if (key != NULL && key->type == type) 844 return need_private ? 845 sensitive_data.host_keys[i] : key; 846 } 847 return NULL; 848 } 849 850 Key * 851 get_hostkey_public_by_type(int type) 852 { 853 return get_hostkey_by_type(type, 0); 854 } 855 856 Key * 857 get_hostkey_private_by_type(int type) 858 { 859 return get_hostkey_by_type(type, 1); 860 } 861 862 Key * 863 get_hostkey_by_index(int ind) 864 { 865 if (ind < 0 || ind >= options.num_host_key_files) 866 return (NULL); 867 return (sensitive_data.host_keys[ind]); 868 } 869 870 Key * 871 get_hostkey_public_by_index(int ind) 872 { 873 if (ind < 0 || ind >= options.num_host_key_files) 874 return (NULL); 875 return (sensitive_data.host_pubkeys[ind]); 876 } 877 878 int 879 get_hostkey_index(Key *key) 880 { 881 int i; 882 883 for (i = 0; i < options.num_host_key_files; i++) { 884 if (key_is_cert(key)) { 885 if (key == sensitive_data.host_certificates[i]) 886 return (i); 887 } else { 888 if (key == sensitive_data.host_keys[i]) 889 return (i); 890 if (key == sensitive_data.host_pubkeys[i]) 891 return (i); 892 } 893 } 894 return (-1); 895 } 896 897 /* 898 * returns 1 if connection should be dropped, 0 otherwise. 899 * dropping starts at connection #max_startups_begin with a probability 900 * of (max_startups_rate/100). the probability increases linearly until 901 * all connections are dropped for startups > max_startups 902 */ 903 static int 904 drop_connection(int startups) 905 { 906 int p, r; 907 908 if (startups < options.max_startups_begin) 909 return 0; 910 if (startups >= options.max_startups) 911 return 1; 912 if (options.max_startups_rate == 100) 913 return 1; 914 915 p = 100 - options.max_startups_rate; 916 p *= startups - options.max_startups_begin; 917 p /= options.max_startups - options.max_startups_begin; 918 p += options.max_startups_rate; 919 r = arc4random_uniform(100); 920 921 debug("drop_connection: p %d, r %d", p, r); 922 return (r < p) ? 1 : 0; 923 } 924 925 __dead static void 926 usage(void) 927 { 928 fprintf(stderr, "%s, %s\n", 929 SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); 930 fprintf(stderr, 931 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 932 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 933 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 934 " [-u len]\n" 935 ); 936 exit(1); 937 } 938 939 static void 940 send_rexec_state(int fd, Buffer *conf) 941 { 942 Buffer m; 943 944 debug3("%s: entering fd = %d config len %d", __func__, fd, 945 buffer_len(conf)); 946 947 /* 948 * Protocol from reexec master to child: 949 * string configuration 950 * u_int ephemeral_key_follows 951 * bignum e (only if ephemeral_key_follows == 1) 952 * bignum n " 953 * bignum d " 954 * bignum iqmp " 955 * bignum p " 956 * bignum q " 957 */ 958 buffer_init(&m); 959 buffer_put_cstring(&m, buffer_ptr(conf)); 960 961 if (sensitive_data.server_key != NULL && 962 sensitive_data.server_key->type == KEY_RSA1) { 963 buffer_put_int(&m, 1); 964 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 965 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 966 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 967 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 968 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 969 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 970 } else 971 buffer_put_int(&m, 0); 972 973 if (ssh_msg_send(fd, 0, &m) == -1) 974 fatal("%s: ssh_msg_send failed", __func__); 975 976 buffer_free(&m); 977 978 debug3("%s: done", __func__); 979 } 980 981 static void 982 recv_rexec_state(int fd, Buffer *conf) 983 { 984 Buffer m; 985 char *cp; 986 u_int len; 987 988 debug3("%s: entering fd = %d", __func__, fd); 989 990 buffer_init(&m); 991 992 if (ssh_msg_recv(fd, &m) == -1) 993 fatal("%s: ssh_msg_recv failed", __func__); 994 if (buffer_get_char(&m) != 0) 995 fatal("%s: rexec version mismatch", __func__); 996 997 cp = buffer_get_string(&m, &len); 998 if (conf != NULL) 999 buffer_append(conf, cp, len + 1); 1000 free(cp); 1001 1002 if (buffer_get_int(&m)) { 1003 if (sensitive_data.server_key != NULL) 1004 key_free(sensitive_data.server_key); 1005 sensitive_data.server_key = key_new_private(KEY_RSA1); 1006 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1007 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1008 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1009 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1010 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1011 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1012 rsa_generate_additional_parameters( 1013 sensitive_data.server_key->rsa); 1014 } 1015 buffer_free(&m); 1016 1017 debug3("%s: done", __func__); 1018 } 1019 1020 /* Accept a connection from inetd */ 1021 static void 1022 server_accept_inetd(int *sock_in, int *sock_out) 1023 { 1024 int fd; 1025 1026 startup_pipe = -1; 1027 if (rexeced_flag) { 1028 close(REEXEC_CONFIG_PASS_FD); 1029 *sock_in = *sock_out = dup(STDIN_FILENO); 1030 if (!debug_flag) { 1031 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1032 close(REEXEC_STARTUP_PIPE_FD); 1033 } 1034 } else { 1035 *sock_in = dup(STDIN_FILENO); 1036 *sock_out = dup(STDOUT_FILENO); 1037 } 1038 /* 1039 * We intentionally do not close the descriptors 0, 1, and 2 1040 * as our code for setting the descriptors won't work if 1041 * ttyfd happens to be one of those. 1042 */ 1043 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1044 dup2(fd, STDIN_FILENO); 1045 dup2(fd, STDOUT_FILENO); 1046 if (!log_stderr) 1047 dup2(fd, STDERR_FILENO); 1048 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1049 close(fd); 1050 } 1051 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1052 } 1053 1054 /* 1055 * Listen for TCP connections 1056 */ 1057 static void 1058 server_listen(void) 1059 { 1060 int ret, listen_sock, on = 1; 1061 struct addrinfo *ai; 1062 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1063 int socksize; 1064 socklen_t socksizelen = sizeof(int); 1065 1066 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1067 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1068 continue; 1069 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1070 fatal("Too many listen sockets. " 1071 "Enlarge MAX_LISTEN_SOCKS"); 1072 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1073 ntop, sizeof(ntop), strport, sizeof(strport), 1074 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1075 error("getnameinfo failed: %.100s", 1076 ssh_gai_strerror(ret)); 1077 continue; 1078 } 1079 /* Create socket for listening. */ 1080 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1081 ai->ai_protocol); 1082 if (listen_sock < 0) { 1083 /* kernel may not support ipv6 */ 1084 verbose("socket: %.100s", strerror(errno)); 1085 continue; 1086 } 1087 if (set_nonblock(listen_sock) == -1) { 1088 close(listen_sock); 1089 continue; 1090 } 1091 /* 1092 * Set socket options. 1093 * Allow local port reuse in TIME_WAIT. 1094 */ 1095 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1096 &on, sizeof(on)) == -1) 1097 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1098 1099 debug("Bind to port %s on %s.", strport, ntop); 1100 1101 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1102 &socksize, &socksizelen); 1103 debug("Server TCP RWIN socket size: %d", socksize); 1104 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1105 1106 /* Bind the socket to the desired port. */ 1107 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1108 error("Bind to port %s on %s failed: %.200s.", 1109 strport, ntop, strerror(errno)); 1110 close(listen_sock); 1111 continue; 1112 } 1113 listen_socks[num_listen_socks] = listen_sock; 1114 num_listen_socks++; 1115 1116 /* Start listening on the port. */ 1117 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1118 fatal("listen on [%s]:%s: %.100s", 1119 ntop, strport, strerror(errno)); 1120 logit("Server listening on %s port %s.", ntop, strport); 1121 } 1122 freeaddrinfo(options.listen_addrs); 1123 1124 if (!num_listen_socks) 1125 fatal("Cannot bind any address."); 1126 } 1127 1128 /* 1129 * The main TCP accept loop. Note that, for the non-debug case, returns 1130 * from this function are in a forked subprocess. 1131 */ 1132 static void 1133 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1134 { 1135 fd_set *fdset; 1136 int i, j, ret, maxfd; 1137 int key_used = 0, startups = 0; 1138 int startup_p[2] = { -1 , -1 }; 1139 struct sockaddr_storage from; 1140 socklen_t fromlen; 1141 pid_t pid; 1142 uint8_t rnd[32]; 1143 1144 /* setup fd set for accept */ 1145 fdset = NULL; 1146 maxfd = 0; 1147 for (i = 0; i < num_listen_socks; i++) 1148 if (listen_socks[i] > maxfd) 1149 maxfd = listen_socks[i]; 1150 /* pipes connected to unauthenticated childs */ 1151 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1152 for (i = 0; i < options.max_startups; i++) 1153 startup_pipes[i] = -1; 1154 1155 /* 1156 * Stay listening for connections until the system crashes or 1157 * the daemon is killed with a signal. 1158 */ 1159 for (;;) { 1160 if (received_sighup) 1161 sighup_restart(); 1162 if (fdset != NULL) 1163 free(fdset); 1164 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1165 sizeof(fd_mask)); 1166 1167 for (i = 0; i < num_listen_socks; i++) 1168 FD_SET(listen_socks[i], fdset); 1169 for (i = 0; i < options.max_startups; i++) 1170 if (startup_pipes[i] != -1) 1171 FD_SET(startup_pipes[i], fdset); 1172 1173 /* Wait in select until there is a connection. */ 1174 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1175 if (ret < 0 && errno != EINTR) 1176 error("select: %.100s", strerror(errno)); 1177 if (received_sigterm) { 1178 logit("Received signal %d; terminating.", 1179 (int) received_sigterm); 1180 close_listen_socks(); 1181 unlink(options.pid_file); 1182 exit(received_sigterm == SIGTERM ? 0 : 255); 1183 } 1184 if (key_used && key_do_regen) { 1185 generate_ephemeral_server_key(); 1186 key_used = 0; 1187 key_do_regen = 0; 1188 } 1189 if (ret < 0) 1190 continue; 1191 1192 for (i = 0; i < options.max_startups; i++) 1193 if (startup_pipes[i] != -1 && 1194 FD_ISSET(startup_pipes[i], fdset)) { 1195 /* 1196 * the read end of the pipe is ready 1197 * if the child has closed the pipe 1198 * after successful authentication 1199 * or if the child has died 1200 */ 1201 close(startup_pipes[i]); 1202 startup_pipes[i] = -1; 1203 startups--; 1204 } 1205 for (i = 0; i < num_listen_socks; i++) { 1206 if (!FD_ISSET(listen_socks[i], fdset)) 1207 continue; 1208 fromlen = sizeof(from); 1209 *newsock = accept(listen_socks[i], 1210 (struct sockaddr *)&from, &fromlen); 1211 if (*newsock < 0) { 1212 if (errno != EINTR && errno != EWOULDBLOCK && 1213 errno != ECONNABORTED) 1214 error("accept: %.100s", 1215 strerror(errno)); 1216 if (errno == EMFILE || errno == ENFILE) 1217 usleep(100 * 1000); 1218 continue; 1219 } 1220 if (unset_nonblock(*newsock) == -1) { 1221 close(*newsock); 1222 continue; 1223 } 1224 if (drop_connection(startups) == 1) { 1225 debug("drop connection #%d", startups); 1226 close(*newsock); 1227 continue; 1228 } 1229 if (pipe(startup_p) == -1) { 1230 close(*newsock); 1231 continue; 1232 } 1233 1234 if (rexec_flag && socketpair(AF_UNIX, 1235 SOCK_STREAM, 0, config_s) == -1) { 1236 error("reexec socketpair: %s", 1237 strerror(errno)); 1238 close(*newsock); 1239 close(startup_p[0]); 1240 close(startup_p[1]); 1241 continue; 1242 } 1243 1244 for (j = 0; j < options.max_startups; j++) 1245 if (startup_pipes[j] == -1) { 1246 startup_pipes[j] = startup_p[0]; 1247 if (maxfd < startup_p[0]) 1248 maxfd = startup_p[0]; 1249 startups++; 1250 break; 1251 } 1252 1253 /* 1254 * Got connection. Fork a child to handle it, unless 1255 * we are in debugging mode. 1256 */ 1257 if (debug_flag) { 1258 /* 1259 * In debugging mode. Close the listening 1260 * socket, and start processing the 1261 * connection without forking. 1262 */ 1263 debug("Server will not fork when running in debugging mode."); 1264 close_listen_socks(); 1265 *sock_in = *newsock; 1266 *sock_out = *newsock; 1267 close(startup_p[0]); 1268 close(startup_p[1]); 1269 startup_pipe = -1; 1270 pid = getpid(); 1271 if (rexec_flag) { 1272 send_rexec_state(config_s[0], 1273 &cfg); 1274 close(config_s[0]); 1275 } 1276 break; 1277 } 1278 1279 /* 1280 * Normal production daemon. Fork, and have 1281 * the child process the connection. The 1282 * parent continues listening. 1283 */ 1284 if ((pid = fork()) == 0) { 1285 /* 1286 * Child. Close the listening and 1287 * max_startup sockets. Start using 1288 * the accepted socket. Reinitialize 1289 * logging (since our pid has changed). 1290 * We break out of the loop to handle 1291 * the connection. 1292 */ 1293 startup_pipe = startup_p[1]; 1294 close_startup_pipes(); 1295 close_listen_socks(); 1296 *sock_in = *newsock; 1297 *sock_out = *newsock; 1298 log_init(__progname, 1299 options.log_level, 1300 options.log_facility, 1301 log_stderr); 1302 if (rexec_flag) 1303 close(config_s[0]); 1304 break; 1305 } 1306 1307 /* Parent. Stay in the loop. */ 1308 if (pid < 0) 1309 error("fork: %.100s", strerror(errno)); 1310 else 1311 debug("Forked child %ld.", (long)pid); 1312 1313 close(startup_p[1]); 1314 1315 if (rexec_flag) { 1316 send_rexec_state(config_s[0], &cfg); 1317 close(config_s[0]); 1318 close(config_s[1]); 1319 } 1320 1321 /* 1322 * Mark that the key has been used (it 1323 * was "given" to the child). 1324 */ 1325 if ((options.protocol & SSH_PROTO_1) && 1326 key_used == 0) { 1327 /* Schedule server key regeneration alarm. */ 1328 signal(SIGALRM, key_regeneration_alarm); 1329 alarm(options.key_regeneration_time); 1330 key_used = 1; 1331 } 1332 1333 close(*newsock); 1334 1335 /* 1336 * Ensure that our random state differs 1337 * from that of the child 1338 */ 1339 if (read(urandom_fd, rnd, sizeof(rnd)) != 1340 sizeof(rnd)) { 1341 fatal("server_accept_loop: " 1342 "entropy read failed"); 1343 } 1344 RAND_seed(rnd, sizeof(rnd)); 1345 arc4random_stir(); 1346 } 1347 1348 /* child process check (or debug mode) */ 1349 if (num_listen_socks < 0) 1350 break; 1351 } 1352 } 1353 1354 1355 /* 1356 * Main program for the daemon. 1357 */ 1358 int 1359 main(int ac, char **av) 1360 { 1361 extern char *optarg; 1362 extern int optind; 1363 int opt, i, j, on = 1; 1364 int sock_in = -1, sock_out = -1, newsock = -1; 1365 const char *remote_ip; 1366 int remote_port; 1367 char *line, *logfile = NULL; 1368 int config_s[2] = { -1 , -1 }; 1369 u_int n; 1370 u_int64_t ibytes, obytes; 1371 mode_t new_umask; 1372 Key *key; 1373 Key *pubkey; 1374 int keytype; 1375 Authctxt *authctxt; 1376 uint8_t rnd[32]; 1377 struct connection_info *connection_info = get_connection_info(0, 0); 1378 1379 /* Save argv. */ 1380 saved_argv = av; 1381 rexec_argc = ac; 1382 1383 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1384 sanitise_stdfd(); 1385 1386 /* Initialize configuration options to their default values. */ 1387 initialize_server_options(&options); 1388 1389 /* Parse command-line arguments. */ 1390 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeE:iqrtQRT46")) != -1) { 1391 switch (opt) { 1392 case '4': 1393 options.address_family = AF_INET; 1394 break; 1395 case '6': 1396 options.address_family = AF_INET6; 1397 break; 1398 case 'f': 1399 config_file_name = optarg; 1400 break; 1401 case 'c': 1402 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1403 fprintf(stderr, "too many host certificates.\n"); 1404 exit(1); 1405 } 1406 options.host_cert_files[options.num_host_cert_files++] = 1407 derelativise_path(optarg); 1408 break; 1409 case 'd': 1410 if (debug_flag == 0) { 1411 debug_flag = 1; 1412 options.log_level = SYSLOG_LEVEL_DEBUG1; 1413 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1414 options.log_level++; 1415 break; 1416 case 'D': 1417 no_daemon_flag = 1; 1418 break; 1419 case 'E': 1420 logfile = xstrdup(optarg); 1421 /* FALLTHROUGH */ 1422 case 'e': 1423 log_stderr = 1; 1424 break; 1425 case 'i': 1426 inetd_flag = 1; 1427 break; 1428 case 'r': 1429 rexec_flag = 0; 1430 break; 1431 case 'R': 1432 rexeced_flag = 1; 1433 inetd_flag = 1; 1434 break; 1435 case 'Q': 1436 /* ignored */ 1437 break; 1438 case 'q': 1439 options.log_level = SYSLOG_LEVEL_QUIET; 1440 break; 1441 case 'b': 1442 options.server_key_bits = (int)strtonum(optarg, 256, 1443 32768, NULL); 1444 break; 1445 case 'p': 1446 options.ports_from_cmdline = 1; 1447 if (options.num_ports >= MAX_PORTS) { 1448 fprintf(stderr, "too many ports.\n"); 1449 exit(1); 1450 } 1451 options.ports[options.num_ports++] = a2port(optarg); 1452 if (options.ports[options.num_ports-1] <= 0) { 1453 fprintf(stderr, "Bad port number.\n"); 1454 exit(1); 1455 } 1456 break; 1457 case 'g': 1458 if ((options.login_grace_time = convtime(optarg)) == -1) { 1459 fprintf(stderr, "Invalid login grace time.\n"); 1460 exit(1); 1461 } 1462 break; 1463 case 'k': 1464 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1465 fprintf(stderr, "Invalid key regeneration interval.\n"); 1466 exit(1); 1467 } 1468 break; 1469 case 'h': 1470 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1471 fprintf(stderr, "too many host keys.\n"); 1472 exit(1); 1473 } 1474 options.host_key_files[options.num_host_key_files++] = 1475 derelativise_path(optarg); 1476 break; 1477 case 't': 1478 test_flag = 1; 1479 break; 1480 case 'T': 1481 test_flag = 2; 1482 break; 1483 case 'C': 1484 if (parse_server_match_testspec(connection_info, 1485 optarg) == -1) 1486 exit(1); 1487 break; 1488 case 'u': 1489 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1490 if (utmp_len > MAXHOSTNAMELEN) { 1491 fprintf(stderr, "Invalid utmp length.\n"); 1492 exit(1); 1493 } 1494 break; 1495 case 'o': 1496 line = xstrdup(optarg); 1497 if (process_server_config_line(&options, line, 1498 "command-line", 0, NULL, NULL) != 0) 1499 exit(1); 1500 free(line); 1501 break; 1502 case '?': 1503 default: 1504 usage(); 1505 break; 1506 } 1507 } 1508 if (rexeced_flag || inetd_flag) 1509 rexec_flag = 0; 1510 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1511 fatal("sshd re-exec requires execution with an absolute path"); 1512 if (rexeced_flag) 1513 closefrom(REEXEC_MIN_FREE_FD); 1514 else 1515 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1516 1517 OpenSSL_add_all_algorithms(); 1518 1519 /* If requested, redirect the logs to the specified logfile. */ 1520 if (logfile != NULL) { 1521 log_redirect_stderr_to(logfile); 1522 free(logfile); 1523 } 1524 /* 1525 * The OpenSSL PRNG is used by key-generation functions we 1526 * rely on for security. Seed it ourselves, so that: 1527 * 1528 * A) it does not seed itself from somewhere questionable, 1529 * such as the libc arc4random or, worse, getpid(). 1530 * B) it does not reopen /dev/urandom on systems where 1531 * this is expensive (generator keyed on open, etc). 1532 * 1533 * Note that /dev/urandom will never return the same data to 1534 * two callers, even if they have the same dup'd reference to it. 1535 */ 1536 if (rexeced_flag) { 1537 urandom_fd = REEXEC_DEVURANDOM_FD; 1538 } else { 1539 urandom_fd = open("/dev/urandom", O_RDONLY); 1540 if (urandom_fd == -1) { 1541 fatal("sshd requires random device"); 1542 } 1543 /* Might as well do this here; why do it later? */ 1544 dup2(urandom_fd, REEXEC_DEVURANDOM_FD); 1545 close(urandom_fd); 1546 urandom_fd = REEXEC_DEVURANDOM_FD; 1547 } 1548 if (read(urandom_fd, rnd, sizeof(rnd)) != sizeof(rnd)) { 1549 fatal("entropy read failed"); 1550 } 1551 RAND_seed(rnd, sizeof(rnd)); 1552 1553 /* 1554 * Force logging to stderr until we have loaded the private host 1555 * key (unless started from inetd) 1556 */ 1557 log_init(__progname, 1558 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1559 SYSLOG_LEVEL_INFO : options.log_level, 1560 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1561 SYSLOG_FACILITY_AUTH : options.log_facility, 1562 log_stderr || !inetd_flag); 1563 1564 sensitive_data.server_key = NULL; 1565 sensitive_data.ssh1_host_key = NULL; 1566 sensitive_data.have_ssh1_key = 0; 1567 sensitive_data.have_ssh2_key = 0; 1568 1569 /* 1570 * If we're doing an extended config test, make sure we have all of 1571 * the parameters we need. If we're not doing an extended test, 1572 * do not silently ignore connection test params. 1573 */ 1574 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1575 fatal("user, host and addr are all required when testing " 1576 "Match configs"); 1577 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1578 fatal("Config test connection parameter (-C) provided without " 1579 "test mode (-T)"); 1580 1581 /* Fetch our configuration */ 1582 buffer_init(&cfg); 1583 if (rexeced_flag) 1584 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1585 else 1586 load_server_config(config_file_name, &cfg); 1587 1588 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1589 &cfg, NULL); 1590 1591 /* Fill in default values for those options not explicitly set. */ 1592 fill_default_server_options(&options); 1593 1594 /* challenge-response is implemented via keyboard interactive */ 1595 if (options.challenge_response_authentication) 1596 options.kbd_interactive_authentication = 1; 1597 1598 /* Check that options are sensible */ 1599 if (options.authorized_keys_command_user == NULL && 1600 (options.authorized_keys_command != NULL && 1601 strcasecmp(options.authorized_keys_command, "none") != 0)) 1602 fatal("AuthorizedKeysCommand set without " 1603 "AuthorizedKeysCommandUser"); 1604 1605 /* 1606 * Check whether there is any path through configured auth methods. 1607 * Unfortunately it is not possible to verify this generally before 1608 * daemonisation in the presence of Match block, but this catches 1609 * and warns for trivial misconfigurations that could break login. 1610 */ 1611 if (options.num_auth_methods != 0) { 1612 if ((options.protocol & SSH_PROTO_1)) 1613 fatal("AuthenticationMethods is not supported with " 1614 "SSH protocol 1"); 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 #ifdef WITH_LDAP_PUBKEY 1635 /* ldap_options_print(&options.lpk); */ 1636 /* XXX initialize/check ldap connection and set *LD */ 1637 if (options.lpk.on) { 1638 if (options.lpk.l_conf && (ldap_parse_lconf(&options.lpk) < 0) ) 1639 error("[LDAP] could not parse %s", options.lpk.l_conf); 1640 if (ldap_connect(&options.lpk) < 0) 1641 error("[LDAP] could not initialize ldap connection"); 1642 } 1643 #endif 1644 debug("sshd version %s, %s", SSH_VERSION, 1645 SSLeay_version(SSLEAY_VERSION)); 1646 1647 /* load host keys */ 1648 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1649 sizeof(Key *)); 1650 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1651 sizeof(Key *)); 1652 for (i = 0; i < options.num_host_key_files; i++) { 1653 sensitive_data.host_keys[i] = NULL; 1654 sensitive_data.host_pubkeys[i] = NULL; 1655 } 1656 1657 if (options.host_key_agent) { 1658 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1659 setenv(SSH_AUTHSOCKET_ENV_NAME, 1660 options.host_key_agent, 1); 1661 have_agent = ssh_agent_present(); 1662 } 1663 1664 for (i = 0; i < options.num_host_key_files; i++) { 1665 key = key_load_private(options.host_key_files[i], "", NULL); 1666 pubkey = key_load_public(options.host_key_files[i], NULL); 1667 sensitive_data.host_keys[i] = key; 1668 sensitive_data.host_pubkeys[i] = pubkey; 1669 1670 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1671 have_agent) { 1672 debug("will rely on agent for hostkey %s", 1673 options.host_key_files[i]); 1674 keytype = pubkey->type; 1675 } else if (key != NULL) { 1676 keytype = key->type; 1677 } else { 1678 error("Could not load host key: %s", 1679 options.host_key_files[i]); 1680 sensitive_data.host_keys[i] = NULL; 1681 sensitive_data.host_pubkeys[i] = NULL; 1682 continue; 1683 } 1684 1685 switch (keytype) { 1686 case KEY_RSA1: 1687 sensitive_data.ssh1_host_key = key; 1688 sensitive_data.have_ssh1_key = 1; 1689 break; 1690 case KEY_RSA: 1691 case KEY_DSA: 1692 case KEY_ECDSA: 1693 sensitive_data.have_ssh2_key = 1; 1694 break; 1695 } 1696 debug("private host key: #%d type %d %s", i, keytype, 1697 key_type(key ? key : pubkey)); 1698 } 1699 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1700 logit("Disabling protocol version 1. Could not load host key"); 1701 options.protocol &= ~SSH_PROTO_1; 1702 } 1703 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1704 logit("Disabling protocol version 2. Could not load host key"); 1705 options.protocol &= ~SSH_PROTO_2; 1706 } 1707 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1708 logit("sshd: no hostkeys available -- exiting."); 1709 exit(1); 1710 } 1711 1712 /* 1713 * Load certificates. They are stored in an array at identical 1714 * indices to the public keys that they relate to. 1715 */ 1716 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1717 sizeof(Key *)); 1718 for (i = 0; i < options.num_host_key_files; i++) 1719 sensitive_data.host_certificates[i] = NULL; 1720 1721 for (i = 0; i < options.num_host_cert_files; i++) { 1722 key = key_load_public(options.host_cert_files[i], NULL); 1723 if (key == NULL) { 1724 error("Could not load host certificate: %s", 1725 options.host_cert_files[i]); 1726 continue; 1727 } 1728 if (!key_is_cert(key)) { 1729 error("Certificate file is not a certificate: %s", 1730 options.host_cert_files[i]); 1731 key_free(key); 1732 continue; 1733 } 1734 /* Find matching private key */ 1735 for (j = 0; j < options.num_host_key_files; j++) { 1736 if (key_equal_public(key, 1737 sensitive_data.host_keys[j])) { 1738 sensitive_data.host_certificates[j] = key; 1739 break; 1740 } 1741 } 1742 if (j >= options.num_host_key_files) { 1743 error("No matching private key for certificate: %s", 1744 options.host_cert_files[i]); 1745 key_free(key); 1746 continue; 1747 } 1748 sensitive_data.host_certificates[j] = key; 1749 debug("host certificate: #%d type %d %s", j, key->type, 1750 key_type(key)); 1751 } 1752 /* Check certain values for sanity. */ 1753 if (options.protocol & SSH_PROTO_1) { 1754 if (options.server_key_bits < 512 || 1755 options.server_key_bits > 32768) { 1756 fprintf(stderr, "Bad server key size.\n"); 1757 exit(1); 1758 } 1759 /* 1760 * Check that server and host key lengths differ sufficiently. This 1761 * is necessary to make double encryption work with rsaref. Oh, I 1762 * hate software patents. I dont know if this can go? Niels 1763 */ 1764 if (options.server_key_bits > 1765 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1766 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1767 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1768 SSH_KEY_BITS_RESERVED) { 1769 options.server_key_bits = 1770 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1771 SSH_KEY_BITS_RESERVED; 1772 debug("Forcing server key to %d bits to make it differ from host key.", 1773 options.server_key_bits); 1774 } 1775 } 1776 1777 if (use_privsep) { 1778 struct stat st; 1779 1780 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1781 fatal("Privilege separation user %s does not exist", 1782 SSH_PRIVSEP_USER); 1783 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1784 (S_ISDIR(st.st_mode) == 0)) 1785 fatal("Missing privilege separation directory: %s", 1786 _PATH_PRIVSEP_CHROOT_DIR); 1787 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1788 fatal("%s must be owned by root and not group or " 1789 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1790 } 1791 1792 if (test_flag > 1) { 1793 if (server_match_spec_complete(connection_info) == 1) 1794 parse_server_match_config(&options, connection_info); 1795 dump_config(&options); 1796 } 1797 1798 /* Configuration looks good, so exit if in test mode. */ 1799 if (test_flag) 1800 exit(0); 1801 1802 if (rexec_flag) { 1803 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1804 for (i = 0; i < rexec_argc; i++) { 1805 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1806 rexec_argv[i] = saved_argv[i]; 1807 } 1808 rexec_argv[rexec_argc] = __UNCONST("-R"); 1809 rexec_argv[rexec_argc + 1] = NULL; 1810 } 1811 1812 /* Ensure that umask disallows at least group and world write */ 1813 new_umask = umask(0077) | 0022; 1814 (void) umask(new_umask); 1815 1816 /* Initialize the log (it is reinitialized below in case we forked). */ 1817 if (debug_flag && (!inetd_flag || rexeced_flag)) 1818 log_stderr = 1; 1819 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1820 1821 /* 1822 * If not in debugging mode, and not started from inetd, disconnect 1823 * from the controlling terminal, and fork. The original process 1824 * exits. 1825 */ 1826 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1827 int fd; 1828 1829 if (daemon(0, 0) < 0) 1830 fatal("daemon() failed: %.200s", strerror(errno)); 1831 1832 /* Disconnect from the controlling tty. */ 1833 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1834 if (fd >= 0) { 1835 (void) ioctl(fd, TIOCNOTTY, NULL); 1836 close(fd); 1837 } 1838 } 1839 /* Reinitialize the log (because of the fork above). */ 1840 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1841 1842 /* Initialize the fast random number generator. */ 1843 arc4random_stir(); 1844 1845 /* Chdir to the root directory so that the current disk can be 1846 unmounted if desired. */ 1847 if (chdir("/") == -1) 1848 error("chdir(\"/\"): %s", strerror(errno)); 1849 1850 /* ignore SIGPIPE */ 1851 signal(SIGPIPE, SIG_IGN); 1852 1853 /* Get a connection, either from inetd or a listening TCP socket */ 1854 if (inetd_flag) { 1855 server_accept_inetd(&sock_in, &sock_out); 1856 } else { 1857 server_listen(); 1858 1859 if (options.protocol & SSH_PROTO_1) 1860 generate_ephemeral_server_key(); 1861 1862 signal(SIGHUP, sighup_handler); 1863 signal(SIGCHLD, main_sigchld_handler); 1864 signal(SIGTERM, sigterm_handler); 1865 signal(SIGQUIT, sigterm_handler); 1866 1867 /* 1868 * Write out the pid file after the sigterm handler 1869 * is setup and the listen sockets are bound 1870 */ 1871 if (!debug_flag) { 1872 FILE *f = fopen(options.pid_file, "w"); 1873 1874 if (f == NULL) { 1875 error("Couldn't create pid file \"%s\": %s", 1876 options.pid_file, strerror(errno)); 1877 } else { 1878 fprintf(f, "%ld\n", (long) getpid()); 1879 fclose(f); 1880 } 1881 } 1882 1883 /* Accept a connection and return in a forked child */ 1884 server_accept_loop(&sock_in, &sock_out, 1885 &newsock, config_s); 1886 } 1887 1888 /* This is the child processing a new connection. */ 1889 setproctitle("%s", "[accepted]"); 1890 1891 /* 1892 * Create a new session and process group since the 4.4BSD 1893 * setlogin() affects the entire process group. We don't 1894 * want the child to be able to affect the parent. 1895 */ 1896 if (!debug_flag && !inetd_flag && setsid() < 0) 1897 error("setsid: %.100s", strerror(errno)); 1898 1899 if (rexec_flag) { 1900 int fd; 1901 1902 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1903 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1904 dup2(newsock, STDIN_FILENO); 1905 dup2(STDIN_FILENO, STDOUT_FILENO); 1906 if (startup_pipe == -1) 1907 close(REEXEC_STARTUP_PIPE_FD); 1908 else 1909 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1910 1911 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1912 close(config_s[1]); 1913 if (startup_pipe != -1) 1914 close(startup_pipe); 1915 1916 execv(rexec_argv[0], rexec_argv); 1917 1918 /* Reexec has failed, fall back and continue */ 1919 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1920 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1921 log_init(__progname, options.log_level, 1922 options.log_facility, log_stderr); 1923 1924 /* Clean up fds */ 1925 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1926 close(config_s[1]); 1927 close(REEXEC_CONFIG_PASS_FD); 1928 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1929 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1930 dup2(fd, STDIN_FILENO); 1931 dup2(fd, STDOUT_FILENO); 1932 if (fd > STDERR_FILENO) 1933 close(fd); 1934 } 1935 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1936 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1937 } 1938 1939 /* Executed child processes don't need these. */ 1940 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1941 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1942 1943 /* 1944 * Disable the key regeneration alarm. We will not regenerate the 1945 * key since we are no longer in a position to give it to anyone. We 1946 * will not restart on SIGHUP since it no longer makes sense. 1947 */ 1948 alarm(0); 1949 signal(SIGALRM, SIG_DFL); 1950 signal(SIGHUP, SIG_DFL); 1951 signal(SIGTERM, SIG_DFL); 1952 signal(SIGQUIT, SIG_DFL); 1953 signal(SIGCHLD, SIG_DFL); 1954 1955 /* 1956 * Register our connection. This turns encryption off because we do 1957 * not have a key. 1958 */ 1959 packet_set_connection(sock_in, sock_out); 1960 packet_set_server(); 1961 1962 /* Set SO_KEEPALIVE if requested. */ 1963 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1964 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1965 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1966 1967 if ((remote_port = get_remote_port()) < 0) { 1968 debug("get_remote_port failed"); 1969 cleanup_exit(255); 1970 } 1971 1972 /* 1973 * We use get_canonical_hostname with usedns = 0 instead of 1974 * get_remote_ipaddr here so IP options will be checked. 1975 */ 1976 (void) get_canonical_hostname(0); 1977 /* 1978 * The rest of the code depends on the fact that 1979 * get_remote_ipaddr() caches the remote ip, even if 1980 * the socket goes away. 1981 */ 1982 remote_ip = get_remote_ipaddr(); 1983 1984 #ifdef LIBWRAP 1985 /* Check whether logins are denied from this host. */ 1986 if (packet_connection_is_on_socket()) { 1987 struct request_info req; 1988 1989 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1990 fromhost(&req); 1991 1992 if (!hosts_access(&req)) { 1993 debug("Connection refused by tcp wrapper"); 1994 refuse(&req); 1995 /* NOTREACHED */ 1996 fatal("libwrap refuse returns"); 1997 } 1998 } 1999 #endif /* LIBWRAP */ 2000 2001 /* Log the connection. */ 2002 verbose("Connection from %.500s port %d", remote_ip, remote_port); 2003 2004 /* set the HPN options for the child */ 2005 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 2006 2007 /* 2008 * We don't want to listen forever unless the other side 2009 * successfully authenticates itself. So we set up an alarm which is 2010 * cleared after successful authentication. A limit of zero 2011 * indicates no limit. Note that we don't set the alarm in debugging 2012 * mode; it is just annoying to have the server exit just when you 2013 * are about to discover the bug. 2014 */ 2015 signal(SIGALRM, grace_alarm_handler); 2016 if (!debug_flag) 2017 alarm(options.login_grace_time); 2018 2019 sshd_exchange_identification(sock_in, sock_out); 2020 2021 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2022 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2023 generate_ephemeral_server_key(); 2024 2025 packet_set_nonblocking(); 2026 2027 /* allocate authentication context */ 2028 authctxt = xcalloc(1, sizeof(*authctxt)); 2029 2030 /* XXX global for cleanup, access from other modules */ 2031 the_authctxt = authctxt; 2032 2033 /* prepare buffer to collect messages to display to user after login */ 2034 buffer_init(&loginmsg); 2035 auth_debug_reset(); 2036 2037 if (use_privsep) { 2038 if (privsep_preauth(authctxt) == 1) 2039 goto authenticated; 2040 } else if (compat20 && have_agent) 2041 auth_conn = ssh_get_authentication_connection(); 2042 2043 /* perform the key exchange */ 2044 /* authenticate user and start session */ 2045 if (compat20) { 2046 do_ssh2_kex(); 2047 do_authentication2(authctxt); 2048 } else { 2049 do_ssh1_kex(); 2050 do_authentication(authctxt); 2051 } 2052 /* 2053 * If we use privilege separation, the unprivileged child transfers 2054 * the current keystate and exits 2055 */ 2056 if (use_privsep) { 2057 mm_send_keystate(pmonitor); 2058 exit(0); 2059 } 2060 2061 authenticated: 2062 /* 2063 * Cancel the alarm we set to limit the time taken for 2064 * authentication. 2065 */ 2066 alarm(0); 2067 signal(SIGALRM, SIG_DFL); 2068 authctxt->authenticated = 1; 2069 if (startup_pipe != -1) { 2070 close(startup_pipe); 2071 startup_pipe = -1; 2072 } 2073 2074 #ifdef USE_PAM 2075 if (options.use_pam) { 2076 do_pam_setcred(1); 2077 do_pam_session(); 2078 } 2079 #endif 2080 2081 /* 2082 * In privilege separation, we fork another child and prepare 2083 * file descriptor passing. 2084 */ 2085 if (use_privsep) { 2086 privsep_postauth(authctxt); 2087 /* the monitor process [priv] will not return */ 2088 if (!compat20) 2089 destroy_sensitive_data(); 2090 } 2091 2092 packet_set_timeout(options.client_alive_interval, 2093 options.client_alive_count_max); 2094 2095 /* Start session. */ 2096 do_authenticated(authctxt); 2097 2098 #ifdef USE_PAM 2099 if (options.use_pam) 2100 finish_pam(); 2101 #endif /* USE_PAM */ 2102 2103 /* The connection has been terminated. */ 2104 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2105 packet_get_state(MODE_OUT, NULL, NULL, NULL, &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 packet_close(); 2111 2112 if (use_privsep) 2113 mm_terminate(); 2114 2115 exit(0); 2116 } 2117 2118 /* 2119 * Decrypt session_key_int using our private server key and private host key 2120 * (key with larger modulus first). 2121 */ 2122 int 2123 ssh1_session_key(BIGNUM *session_key_int) 2124 { 2125 int rsafail = 0; 2126 2127 if (BN_cmp(sensitive_data.server_key->rsa->n, 2128 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2129 /* Server key has bigger modulus. */ 2130 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2131 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2132 SSH_KEY_BITS_RESERVED) { 2133 fatal("do_connection: %s: " 2134 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2135 get_remote_ipaddr(), 2136 BN_num_bits(sensitive_data.server_key->rsa->n), 2137 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2138 SSH_KEY_BITS_RESERVED); 2139 } 2140 if (rsa_private_decrypt(session_key_int, session_key_int, 2141 sensitive_data.server_key->rsa) <= 0) 2142 rsafail++; 2143 if (rsa_private_decrypt(session_key_int, session_key_int, 2144 sensitive_data.ssh1_host_key->rsa) <= 0) 2145 rsafail++; 2146 } else { 2147 /* Host key has bigger modulus (or they are equal). */ 2148 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2149 BN_num_bits(sensitive_data.server_key->rsa->n) + 2150 SSH_KEY_BITS_RESERVED) { 2151 fatal("do_connection: %s: " 2152 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2153 get_remote_ipaddr(), 2154 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2155 BN_num_bits(sensitive_data.server_key->rsa->n), 2156 SSH_KEY_BITS_RESERVED); 2157 } 2158 if (rsa_private_decrypt(session_key_int, session_key_int, 2159 sensitive_data.ssh1_host_key->rsa) < 0) 2160 rsafail++; 2161 if (rsa_private_decrypt(session_key_int, session_key_int, 2162 sensitive_data.server_key->rsa) < 0) 2163 rsafail++; 2164 } 2165 return (rsafail); 2166 } 2167 /* 2168 * SSH1 key exchange 2169 */ 2170 static void 2171 do_ssh1_kex(void) 2172 { 2173 int i, len; 2174 int rsafail = 0; 2175 BIGNUM *session_key_int; 2176 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2177 u_char cookie[8]; 2178 u_int cipher_type, auth_mask, protocol_flags; 2179 2180 /* 2181 * Generate check bytes that the client must send back in the user 2182 * packet in order for it to be accepted; this is used to defy ip 2183 * spoofing attacks. Note that this only works against somebody 2184 * doing IP spoofing from a remote machine; any machine on the local 2185 * network can still see outgoing packets and catch the random 2186 * cookie. This only affects rhosts authentication, and this is one 2187 * of the reasons why it is inherently insecure. 2188 */ 2189 arc4random_buf(cookie, sizeof(cookie)); 2190 2191 /* 2192 * Send our public key. We include in the packet 64 bits of random 2193 * data that must be matched in the reply in order to prevent IP 2194 * spoofing. 2195 */ 2196 packet_start(SSH_SMSG_PUBLIC_KEY); 2197 for (i = 0; i < 8; i++) 2198 packet_put_char(cookie[i]); 2199 2200 /* Store our public server RSA key. */ 2201 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2202 packet_put_bignum(sensitive_data.server_key->rsa->e); 2203 packet_put_bignum(sensitive_data.server_key->rsa->n); 2204 2205 /* Store our public host RSA key. */ 2206 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2207 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2208 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2209 2210 /* Put protocol flags. */ 2211 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2212 2213 /* Declare which ciphers we support. */ 2214 packet_put_int(cipher_mask_ssh1(0)); 2215 2216 /* Declare supported authentication types. */ 2217 auth_mask = 0; 2218 if (options.rhosts_rsa_authentication) 2219 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2220 if (options.rsa_authentication) 2221 auth_mask |= 1 << SSH_AUTH_RSA; 2222 #if defined(KRB4) || defined(KRB5) 2223 if (options.kerberos_authentication) 2224 auth_mask |= 1 << SSH_AUTH_KERBEROS; 2225 #endif 2226 #if defined(AFS) || defined(KRB5) 2227 if (options.kerberos_tgt_passing) 2228 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; 2229 #endif 2230 #ifdef AFS 2231 if (options.afs_token_passing) 2232 auth_mask |= 1 << SSH_PASS_AFS_TOKEN; 2233 #endif 2234 if (options.challenge_response_authentication == 1) 2235 auth_mask |= 1 << SSH_AUTH_TIS; 2236 if (options.password_authentication) 2237 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2238 packet_put_int(auth_mask); 2239 2240 /* Send the packet and wait for it to be sent. */ 2241 packet_send(); 2242 packet_write_wait(); 2243 2244 debug("Sent %d bit server key and %d bit host key.", 2245 BN_num_bits(sensitive_data.server_key->rsa->n), 2246 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2247 2248 /* Read clients reply (cipher type and session key). */ 2249 packet_read_expect(SSH_CMSG_SESSION_KEY); 2250 2251 /* Get cipher type and check whether we accept this. */ 2252 cipher_type = packet_get_char(); 2253 2254 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2255 packet_disconnect("Warning: client selects unsupported cipher."); 2256 2257 /* Get check bytes from the packet. These must match those we 2258 sent earlier with the public key packet. */ 2259 for (i = 0; i < 8; i++) 2260 if (cookie[i] != packet_get_char()) 2261 packet_disconnect("IP Spoofing check bytes do not match."); 2262 2263 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2264 2265 /* Get the encrypted integer. */ 2266 if ((session_key_int = BN_new()) == NULL) 2267 fatal("do_ssh1_kex: BN_new failed"); 2268 packet_get_bignum(session_key_int); 2269 2270 protocol_flags = packet_get_int(); 2271 packet_set_protocol_flags(protocol_flags); 2272 packet_check_eom(); 2273 2274 /* Decrypt session_key_int using host/server keys */ 2275 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2276 2277 /* 2278 * Extract session key from the decrypted integer. The key is in the 2279 * least significant 256 bits of the integer; the first byte of the 2280 * key is in the highest bits. 2281 */ 2282 if (!rsafail) { 2283 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2284 len = BN_num_bytes(session_key_int); 2285 if (len < 0 || (u_int)len > sizeof(session_key)) { 2286 error("do_ssh1_kex: bad session key len from %s: " 2287 "session_key_int %d > sizeof(session_key) %lu", 2288 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2289 rsafail++; 2290 } else { 2291 memset(session_key, 0, sizeof(session_key)); 2292 BN_bn2bin(session_key_int, 2293 session_key + sizeof(session_key) - len); 2294 2295 derive_ssh1_session_id( 2296 sensitive_data.ssh1_host_key->rsa->n, 2297 sensitive_data.server_key->rsa->n, 2298 cookie, session_id); 2299 /* 2300 * Xor the first 16 bytes of the session key with the 2301 * session id. 2302 */ 2303 for (i = 0; i < 16; i++) 2304 session_key[i] ^= session_id[i]; 2305 } 2306 } 2307 if (rsafail) { 2308 int bytes = BN_num_bytes(session_key_int); 2309 u_char *buf = xmalloc(bytes); 2310 MD5_CTX md; 2311 2312 logit("do_connection: generating a fake encryption key"); 2313 BN_bn2bin(session_key_int, buf); 2314 MD5_Init(&md); 2315 MD5_Update(&md, buf, bytes); 2316 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2317 MD5_Final(session_key, &md); 2318 MD5_Init(&md); 2319 MD5_Update(&md, session_key, 16); 2320 MD5_Update(&md, buf, bytes); 2321 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2322 MD5_Final(session_key + 16, &md); 2323 memset(buf, 0, bytes); 2324 free(buf); 2325 for (i = 0; i < 16; i++) 2326 session_id[i] = session_key[i] ^ session_key[i + 16]; 2327 } 2328 /* Destroy the private and public keys. No longer. */ 2329 destroy_sensitive_data(); 2330 2331 if (use_privsep) 2332 mm_ssh1_session_id(session_id); 2333 2334 /* Destroy the decrypted integer. It is no longer needed. */ 2335 BN_clear_free(session_key_int); 2336 2337 /* Set the session key. From this on all communications will be encrypted. */ 2338 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2339 2340 /* Destroy our copy of the session key. It is no longer needed. */ 2341 memset(session_key, 0, sizeof(session_key)); 2342 2343 debug("Received session key; encryption turned on."); 2344 2345 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2346 packet_start(SSH_SMSG_SUCCESS); 2347 packet_send(); 2348 packet_write_wait(); 2349 } 2350 2351 void 2352 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen, 2353 u_char *data, u_int dlen) 2354 { 2355 if (privkey) { 2356 if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0)) 2357 fatal("%s: key_sign failed", __func__); 2358 } else if (use_privsep) { 2359 if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0) 2360 fatal("%s: pubkey_sign failed", __func__); 2361 } else { 2362 if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data, 2363 dlen)) 2364 fatal("%s: ssh_agent_sign failed", __func__); 2365 } 2366 } 2367 2368 /* 2369 * SSH2 key exchange: diffie-hellman-group1-sha1 2370 */ 2371 static void 2372 do_ssh2_kex(void) 2373 { 2374 Kex *kex; 2375 2376 myflag++; 2377 debug ("MYFLAG IS %d", myflag); 2378 if (options.ciphers != NULL) { 2379 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2380 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2381 } else if (options.none_enabled == 1) { 2382 debug ("WARNING: None cipher enabled"); 2383 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2384 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2385 } 2386 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2387 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2388 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2389 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2390 2391 if (options.macs != NULL) { 2392 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2393 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2394 } 2395 if (options.compression == COMP_NONE) { 2396 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2397 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2398 } else if (options.compression == COMP_DELAYED) { 2399 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2400 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2401 } 2402 if (options.kex_algorithms != NULL) 2403 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2404 2405 if (options.rekey_limit || options.rekey_interval) 2406 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 2407 (time_t)options.rekey_interval); 2408 2409 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2410 2411 /* start key exchange */ 2412 kex = kex_setup(myproposal); 2413 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2414 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2415 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2416 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2417 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2418 kex->server = 1; 2419 kex->client_version_string=client_version_string; 2420 kex->server_version_string=server_version_string; 2421 kex->load_host_public_key=&get_hostkey_public_by_type; 2422 kex->load_host_private_key=&get_hostkey_private_by_type; 2423 kex->host_key_index=&get_hostkey_index; 2424 kex->sign = sshd_hostkey_sign; 2425 2426 xxx_kex = kex; 2427 2428 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2429 2430 session_id2 = kex->session_id; 2431 session_id2_len = kex->session_id_len; 2432 2433 #ifdef DEBUG_KEXDH 2434 /* send 1st encrypted/maced/compressed message */ 2435 packet_start(SSH2_MSG_IGNORE); 2436 packet_put_cstring("markus"); 2437 packet_send(); 2438 packet_write_wait(); 2439 #endif 2440 debug("KEX done"); 2441 } 2442 2443 /* server specific fatal cleanup */ 2444 void 2445 cleanup_exit(int i) 2446 { 2447 if (the_authctxt) { 2448 do_cleanup(the_authctxt); 2449 if (use_privsep && privsep_is_preauth && pmonitor->m_pid > 1) { 2450 debug("Killing privsep child %d", pmonitor->m_pid); 2451 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2452 errno != ESRCH) 2453 error("%s: kill(%d): %s", __func__, 2454 pmonitor->m_pid, strerror(errno)); 2455 } 2456 } 2457 _exit(i); 2458 } 2459