1 /* $OpenBSD: sshd.c,v 1.591 2022/09/17 10:34:29 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 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 #ifdef HAVE_POLL_H 68 #include <poll.h> 69 #endif 70 #include <pwd.h> 71 #include <signal.h> 72 #include <stdarg.h> 73 #include <stdio.h> 74 #include <stdlib.h> 75 #include <string.h> 76 #include <unistd.h> 77 #include <limits.h> 78 79 #ifdef WITH_OPENSSL 80 #include <openssl/dh.h> 81 #include <openssl/bn.h> 82 #include <openssl/rand.h> 83 #include "openbsd-compat/openssl-compat.h" 84 #endif 85 86 #ifdef HAVE_SECUREWARE 87 #include <sys/security.h> 88 #include <prot.h> 89 #endif 90 91 #include "xmalloc.h" 92 #include "ssh.h" 93 #include "ssh2.h" 94 #include "sshpty.h" 95 #include "packet.h" 96 #include "log.h" 97 #include "sshbuf.h" 98 #include "misc.h" 99 #include "match.h" 100 #include "servconf.h" 101 #include "uidswap.h" 102 #include "compat.h" 103 #include "cipher.h" 104 #include "digest.h" 105 #include "sshkey.h" 106 #include "kex.h" 107 #include "myproposal.h" 108 #include "authfile.h" 109 #include "pathnames.h" 110 #include "atomicio.h" 111 #include "canohost.h" 112 #include "hostfile.h" 113 #include "auth.h" 114 #include "authfd.h" 115 #include "msg.h" 116 #include "dispatch.h" 117 #include "channels.h" 118 #include "session.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 "auth-options.h" 126 #include "version.h" 127 #include "ssherr.h" 128 #include "sk-api.h" 129 #include "srclimit.h" 130 #include "dh.h" 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 /* 155 * Indicating that the daemon should only test the configuration and keys. 156 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 157 * configuration, optionally using connection information provided by the 158 * "-C" flag. 159 */ 160 static int test_flag = 0; 161 162 /* Flag indicating that the daemon is being started from inetd. */ 163 static int inetd_flag = 0; 164 165 /* Flag indicating that sshd should not detach and become a daemon. */ 166 static int no_daemon_flag = 0; 167 168 /* debug goes to stderr unless inetd_flag is set */ 169 static int log_stderr = 0; 170 171 /* Saved arguments to main(). */ 172 static char **saved_argv; 173 static int saved_argc; 174 175 /* re-exec */ 176 static int rexeced_flag = 0; 177 static int rexec_flag = 1; 178 static int rexec_argc = 0; 179 static char **rexec_argv; 180 181 /* 182 * The sockets that the server is listening; this is used in the SIGHUP 183 * signal handler. 184 */ 185 #define MAX_LISTEN_SOCKS 16 186 static int listen_socks[MAX_LISTEN_SOCKS]; 187 static int num_listen_socks = 0; 188 189 /* Daemon's agent connection */ 190 int auth_sock = -1; 191 static int have_agent = 0; 192 193 /* 194 * Any really sensitive data in the application is contained in this 195 * structure. The idea is that this structure could be locked into memory so 196 * that the pages do not get written into swap. However, there are some 197 * problems. The private key contains BIGNUMs, and we do not (in principle) 198 * have access to the internals of them, and locking just the structure is 199 * not very useful. Currently, memory locking is not implemented. 200 */ 201 struct { 202 struct sshkey **host_keys; /* all private host keys */ 203 struct sshkey **host_pubkeys; /* all public host keys */ 204 struct sshkey **host_certificates; /* all public host certificates */ 205 int have_ssh2_key; 206 } sensitive_data; 207 208 /* This is set to true when a signal is received. */ 209 static volatile sig_atomic_t received_sighup = 0; 210 static volatile sig_atomic_t received_sigterm = 0; 211 212 /* record remote hostname or ip */ 213 u_int utmp_len = HOST_NAME_MAX+1; 214 215 /* 216 * startup_pipes/flags are used for tracking children of the listening sshd 217 * process early in their lifespans. This tracking is needed for three things: 218 * 219 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 220 * connections. 221 * 2) Avoiding a race condition for SIGHUP processing, where child processes 222 * may have listen_socks open that could collide with main listener process 223 * after it restarts. 224 * 3) Ensuring that rexec'd sshd processes have received their initial state 225 * from the parent listen process before handling SIGHUP. 226 * 227 * Child processes signal that they have completed closure of the listen_socks 228 * and (if applicable) received their rexec state by sending a char over their 229 * sock. Child processes signal that authentication has completed by closing 230 * the sock (or by exiting). 231 */ 232 static int *startup_pipes = NULL; 233 static int *startup_flags = NULL; /* Indicates child closed listener */ 234 static int startup_pipe = -1; /* in child */ 235 236 /* variables used for privilege separation */ 237 int use_privsep = -1; 238 struct monitor *pmonitor = NULL; 239 int privsep_is_preauth = 1; 240 static int privsep_chroot = 1; 241 242 /* global connection state and authentication contexts */ 243 Authctxt *the_authctxt = NULL; 244 struct ssh *the_active_state; 245 246 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 247 struct sshauthopt *auth_opts = NULL; 248 249 /* sshd_config buffer */ 250 struct sshbuf *cfg; 251 252 /* Included files from the configuration file */ 253 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 254 255 /* message to be displayed after login */ 256 struct sshbuf *loginmsg; 257 258 /* Unprivileged user */ 259 struct passwd *privsep_pw = NULL; 260 261 /* Prototypes for various functions defined later in this file. */ 262 void destroy_sensitive_data(void); 263 void demote_sensitive_data(void); 264 static void do_ssh2_kex(struct ssh *); 265 266 static char *listener_proctitle; 267 268 /* 269 * Close all listening sockets 270 */ 271 static void 272 close_listen_socks(void) 273 { 274 int i; 275 276 for (i = 0; i < num_listen_socks; i++) 277 close(listen_socks[i]); 278 num_listen_socks = 0; 279 } 280 281 static void 282 close_startup_pipes(void) 283 { 284 int i; 285 286 if (startup_pipes) 287 for (i = 0; i < options.max_startups; i++) 288 if (startup_pipes[i] != -1) 289 close(startup_pipes[i]); 290 } 291 292 /* 293 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 294 * the effect is to reread the configuration file (and to regenerate 295 * the server key). 296 */ 297 298 /*ARGSUSED*/ 299 static void 300 sighup_handler(int sig) 301 { 302 received_sighup = 1; 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 if (options.pid_file != NULL) 314 unlink(options.pid_file); 315 platform_pre_restart(); 316 close_listen_socks(); 317 close_startup_pipes(); 318 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 319 execv(saved_argv[0], saved_argv); 320 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 321 strerror(errno)); 322 exit(1); 323 } 324 325 /* 326 * Generic signal handler for terminating signals in the master daemon. 327 */ 328 /*ARGSUSED*/ 329 static void 330 sigterm_handler(int sig) 331 { 332 received_sigterm = sig; 333 } 334 335 /* 336 * SIGCHLD handler. This is called whenever a child dies. This will then 337 * reap any zombies left by exited children. 338 */ 339 /*ARGSUSED*/ 340 static void 341 main_sigchld_handler(int sig) 342 { 343 int save_errno = errno; 344 pid_t pid; 345 int status; 346 347 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 348 (pid == -1 && errno == EINTR)) 349 ; 350 errno = save_errno; 351 } 352 353 /* 354 * Signal handler for the alarm after the login grace period has expired. 355 */ 356 /*ARGSUSED*/ 357 static void 358 grace_alarm_handler(int sig) 359 { 360 /* 361 * Try to kill any processes that we have spawned, E.g. authorized 362 * keys command helpers or privsep children. 363 */ 364 if (getpgid(0) == getpid()) { 365 ssh_signal(SIGTERM, SIG_IGN); 366 kill(0, SIGTERM); 367 } 368 369 /* Log error and exit. */ 370 sigdie("Timeout before authentication for %s port %d", 371 ssh_remote_ipaddr(the_active_state), 372 ssh_remote_port(the_active_state)); 373 } 374 375 /* Destroy the host and server keys. They will no longer be needed. */ 376 void 377 destroy_sensitive_data(void) 378 { 379 u_int i; 380 381 for (i = 0; i < options.num_host_key_files; i++) { 382 if (sensitive_data.host_keys[i]) { 383 sshkey_free(sensitive_data.host_keys[i]); 384 sensitive_data.host_keys[i] = NULL; 385 } 386 if (sensitive_data.host_certificates[i]) { 387 sshkey_free(sensitive_data.host_certificates[i]); 388 sensitive_data.host_certificates[i] = NULL; 389 } 390 } 391 } 392 393 /* Demote private to public keys for network child */ 394 void 395 demote_sensitive_data(void) 396 { 397 struct sshkey *tmp; 398 u_int i; 399 int r; 400 401 for (i = 0; i < options.num_host_key_files; i++) { 402 if (sensitive_data.host_keys[i]) { 403 if ((r = sshkey_from_private( 404 sensitive_data.host_keys[i], &tmp)) != 0) 405 fatal_r(r, "could not demote host %s key", 406 sshkey_type(sensitive_data.host_keys[i])); 407 sshkey_free(sensitive_data.host_keys[i]); 408 sensitive_data.host_keys[i] = tmp; 409 } 410 /* Certs do not need demotion */ 411 } 412 } 413 414 static void 415 reseed_prngs(void) 416 { 417 u_int32_t rnd[256]; 418 419 #ifdef WITH_OPENSSL 420 RAND_poll(); 421 #endif 422 arc4random_stir(); /* noop on recent arc4random() implementations */ 423 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 424 425 #ifdef WITH_OPENSSL 426 RAND_seed(rnd, sizeof(rnd)); 427 /* give libcrypto a chance to notice the PID change */ 428 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 429 fatal("%s: RAND_bytes failed", __func__); 430 #endif 431 432 explicit_bzero(rnd, sizeof(rnd)); 433 } 434 435 static void 436 privsep_preauth_child(void) 437 { 438 gid_t gidset[1]; 439 440 /* Enable challenge-response authentication for privilege separation */ 441 privsep_challenge_enable(); 442 443 #ifdef GSSAPI 444 /* Cache supported mechanism OIDs for later use */ 445 ssh_gssapi_prepare_supported_oids(); 446 #endif 447 448 reseed_prngs(); 449 450 /* Demote the private keys to public keys. */ 451 demote_sensitive_data(); 452 453 /* Demote the child */ 454 if (privsep_chroot) { 455 /* Change our root directory */ 456 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 457 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 458 strerror(errno)); 459 if (chdir("/") == -1) 460 fatal("chdir(\"/\"): %s", strerror(errno)); 461 462 /* Drop our privileges */ 463 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 464 (u_int)privsep_pw->pw_gid); 465 gidset[0] = privsep_pw->pw_gid; 466 if (setgroups(1, gidset) == -1) 467 fatal("setgroups: %.100s", strerror(errno)); 468 permanently_set_uid(privsep_pw); 469 } 470 } 471 472 static int 473 privsep_preauth(struct ssh *ssh) 474 { 475 int status, r; 476 pid_t pid; 477 struct ssh_sandbox *box = NULL; 478 479 /* Set up unprivileged child process to deal with network data */ 480 pmonitor = monitor_init(); 481 /* Store a pointer to the kex for later rekeying */ 482 pmonitor->m_pkex = &ssh->kex; 483 484 if (use_privsep == PRIVSEP_ON) 485 box = ssh_sandbox_init(pmonitor); 486 pid = fork(); 487 if (pid == -1) { 488 fatal("fork of unprivileged child failed"); 489 } else if (pid != 0) { 490 debug2("Network child is on pid %ld", (long)pid); 491 492 pmonitor->m_pid = pid; 493 if (have_agent) { 494 r = ssh_get_authentication_socket(&auth_sock); 495 if (r != 0) { 496 error_r(r, "Could not get agent socket"); 497 have_agent = 0; 498 } 499 } 500 if (box != NULL) 501 ssh_sandbox_parent_preauth(box, pid); 502 monitor_child_preauth(ssh, pmonitor); 503 504 /* Wait for the child's exit status */ 505 while (waitpid(pid, &status, 0) == -1) { 506 if (errno == EINTR) 507 continue; 508 pmonitor->m_pid = -1; 509 fatal_f("waitpid: %s", strerror(errno)); 510 } 511 privsep_is_preauth = 0; 512 pmonitor->m_pid = -1; 513 if (WIFEXITED(status)) { 514 if (WEXITSTATUS(status) != 0) 515 fatal_f("preauth child exited with status %d", 516 WEXITSTATUS(status)); 517 } else if (WIFSIGNALED(status)) 518 fatal_f("preauth child terminated by signal %d", 519 WTERMSIG(status)); 520 if (box != NULL) 521 ssh_sandbox_parent_finish(box); 522 return 1; 523 } else { 524 /* child */ 525 close(pmonitor->m_sendfd); 526 close(pmonitor->m_log_recvfd); 527 528 /* Arrange for logging to be sent to the monitor */ 529 set_log_handler(mm_log_handler, pmonitor); 530 531 privsep_preauth_child(); 532 setproctitle("%s", "[net]"); 533 if (box != NULL) 534 ssh_sandbox_child(box); 535 536 return 0; 537 } 538 } 539 540 static void 541 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 542 { 543 #ifdef DISABLE_FD_PASSING 544 if (1) { 545 #else 546 if (authctxt->pw->pw_uid == 0) { 547 #endif 548 /* File descriptor passing is broken or root login */ 549 use_privsep = 0; 550 goto skip; 551 } 552 553 /* New socket pair */ 554 monitor_reinit(pmonitor); 555 556 pmonitor->m_pid = fork(); 557 if (pmonitor->m_pid == -1) 558 fatal("fork of unprivileged child failed"); 559 else if (pmonitor->m_pid != 0) { 560 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 561 sshbuf_reset(loginmsg); 562 monitor_clear_keystate(ssh, pmonitor); 563 monitor_child_postauth(ssh, pmonitor); 564 565 /* NEVERREACHED */ 566 exit(0); 567 } 568 569 /* child */ 570 571 close(pmonitor->m_sendfd); 572 pmonitor->m_sendfd = -1; 573 574 /* Demote the private keys to public keys. */ 575 demote_sensitive_data(); 576 577 reseed_prngs(); 578 579 /* Drop privileges */ 580 do_setusercontext(authctxt->pw); 581 582 skip: 583 /* It is safe now to apply the key state */ 584 monitor_apply_keystate(ssh, pmonitor); 585 586 /* 587 * Tell the packet layer that authentication was successful, since 588 * this information is not part of the key state. 589 */ 590 ssh_packet_set_authenticated(ssh); 591 } 592 593 static void 594 append_hostkey_type(struct sshbuf *b, const char *s) 595 { 596 int r; 597 598 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 599 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 600 return; 601 } 602 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 603 fatal_fr(r, "sshbuf_putf"); 604 } 605 606 static char * 607 list_hostkey_types(void) 608 { 609 struct sshbuf *b; 610 struct sshkey *key; 611 char *ret; 612 u_int i; 613 614 if ((b = sshbuf_new()) == NULL) 615 fatal_f("sshbuf_new failed"); 616 for (i = 0; i < options.num_host_key_files; i++) { 617 key = sensitive_data.host_keys[i]; 618 if (key == NULL) 619 key = sensitive_data.host_pubkeys[i]; 620 if (key == NULL) 621 continue; 622 switch (key->type) { 623 case KEY_RSA: 624 /* for RSA we also support SHA2 signatures */ 625 append_hostkey_type(b, "rsa-sha2-512"); 626 append_hostkey_type(b, "rsa-sha2-256"); 627 /* FALLTHROUGH */ 628 case KEY_DSA: 629 case KEY_ECDSA: 630 case KEY_ED25519: 631 case KEY_ECDSA_SK: 632 case KEY_ED25519_SK: 633 case KEY_XMSS: 634 append_hostkey_type(b, sshkey_ssh_name(key)); 635 break; 636 } 637 /* If the private key has a cert peer, then list that too */ 638 key = sensitive_data.host_certificates[i]; 639 if (key == NULL) 640 continue; 641 switch (key->type) { 642 case KEY_RSA_CERT: 643 /* for RSA we also support SHA2 signatures */ 644 append_hostkey_type(b, 645 "rsa-sha2-512-cert-v01@openssh.com"); 646 append_hostkey_type(b, 647 "rsa-sha2-256-cert-v01@openssh.com"); 648 /* FALLTHROUGH */ 649 case KEY_DSA_CERT: 650 case KEY_ECDSA_CERT: 651 case KEY_ED25519_CERT: 652 case KEY_ECDSA_SK_CERT: 653 case KEY_ED25519_SK_CERT: 654 case KEY_XMSS_CERT: 655 append_hostkey_type(b, sshkey_ssh_name(key)); 656 break; 657 } 658 } 659 if ((ret = sshbuf_dup_string(b)) == NULL) 660 fatal_f("sshbuf_dup_string failed"); 661 sshbuf_free(b); 662 debug_f("%s", ret); 663 return ret; 664 } 665 666 static struct sshkey * 667 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 668 { 669 u_int i; 670 struct sshkey *key; 671 672 for (i = 0; i < options.num_host_key_files; i++) { 673 switch (type) { 674 case KEY_RSA_CERT: 675 case KEY_DSA_CERT: 676 case KEY_ECDSA_CERT: 677 case KEY_ED25519_CERT: 678 case KEY_ECDSA_SK_CERT: 679 case KEY_ED25519_SK_CERT: 680 case KEY_XMSS_CERT: 681 key = sensitive_data.host_certificates[i]; 682 break; 683 default: 684 key = sensitive_data.host_keys[i]; 685 if (key == NULL && !need_private) 686 key = sensitive_data.host_pubkeys[i]; 687 break; 688 } 689 if (key == NULL || key->type != type) 690 continue; 691 switch (type) { 692 case KEY_ECDSA: 693 case KEY_ECDSA_SK: 694 case KEY_ECDSA_CERT: 695 case KEY_ECDSA_SK_CERT: 696 if (key->ecdsa_nid != nid) 697 continue; 698 /* FALLTHROUGH */ 699 default: 700 return need_private ? 701 sensitive_data.host_keys[i] : key; 702 } 703 } 704 return NULL; 705 } 706 707 struct sshkey * 708 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 709 { 710 return get_hostkey_by_type(type, nid, 0, ssh); 711 } 712 713 struct sshkey * 714 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 715 { 716 return get_hostkey_by_type(type, nid, 1, ssh); 717 } 718 719 struct sshkey * 720 get_hostkey_by_index(int ind) 721 { 722 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 723 return (NULL); 724 return (sensitive_data.host_keys[ind]); 725 } 726 727 struct sshkey * 728 get_hostkey_public_by_index(int ind, struct ssh *ssh) 729 { 730 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 731 return (NULL); 732 return (sensitive_data.host_pubkeys[ind]); 733 } 734 735 int 736 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 737 { 738 u_int i; 739 740 for (i = 0; i < options.num_host_key_files; i++) { 741 if (sshkey_is_cert(key)) { 742 if (key == sensitive_data.host_certificates[i] || 743 (compare && sensitive_data.host_certificates[i] && 744 sshkey_equal(key, 745 sensitive_data.host_certificates[i]))) 746 return (i); 747 } else { 748 if (key == sensitive_data.host_keys[i] || 749 (compare && sensitive_data.host_keys[i] && 750 sshkey_equal(key, sensitive_data.host_keys[i]))) 751 return (i); 752 if (key == sensitive_data.host_pubkeys[i] || 753 (compare && sensitive_data.host_pubkeys[i] && 754 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 755 return (i); 756 } 757 } 758 return (-1); 759 } 760 761 /* Inform the client of all hostkeys */ 762 static void 763 notify_hostkeys(struct ssh *ssh) 764 { 765 struct sshbuf *buf; 766 struct sshkey *key; 767 u_int i, nkeys; 768 int r; 769 char *fp; 770 771 /* Some clients cannot cope with the hostkeys message, skip those. */ 772 if (ssh->compat & SSH_BUG_HOSTKEYS) 773 return; 774 775 if ((buf = sshbuf_new()) == NULL) 776 fatal_f("sshbuf_new"); 777 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 778 key = get_hostkey_public_by_index(i, ssh); 779 if (key == NULL || key->type == KEY_UNSPEC || 780 sshkey_is_cert(key)) 781 continue; 782 fp = sshkey_fingerprint(key, options.fingerprint_hash, 783 SSH_FP_DEFAULT); 784 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 785 free(fp); 786 if (nkeys == 0) { 787 /* 788 * Start building the request when we find the 789 * first usable key. 790 */ 791 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 792 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 793 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 794 sshpkt_fatal(ssh, r, "%s: start request", __func__); 795 } 796 /* Append the key to the request */ 797 sshbuf_reset(buf); 798 if ((r = sshkey_putb(key, buf)) != 0) 799 fatal_fr(r, "couldn't put hostkey %d", i); 800 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 801 sshpkt_fatal(ssh, r, "%s: append key", __func__); 802 nkeys++; 803 } 804 debug3_f("sent %u hostkeys", nkeys); 805 if (nkeys == 0) 806 fatal_f("no hostkeys"); 807 if ((r = sshpkt_send(ssh)) != 0) 808 sshpkt_fatal(ssh, r, "%s: send", __func__); 809 sshbuf_free(buf); 810 } 811 812 /* 813 * returns 1 if connection should be dropped, 0 otherwise. 814 * dropping starts at connection #max_startups_begin with a probability 815 * of (max_startups_rate/100). the probability increases linearly until 816 * all connections are dropped for startups > max_startups 817 */ 818 static int 819 should_drop_connection(int startups) 820 { 821 int p, r; 822 823 if (startups < options.max_startups_begin) 824 return 0; 825 if (startups >= options.max_startups) 826 return 1; 827 if (options.max_startups_rate == 100) 828 return 1; 829 830 p = 100 - options.max_startups_rate; 831 p *= startups - options.max_startups_begin; 832 p /= options.max_startups - options.max_startups_begin; 833 p += options.max_startups_rate; 834 r = arc4random_uniform(100); 835 836 debug_f("p %d, r %d", p, r); 837 return (r < p) ? 1 : 0; 838 } 839 840 /* 841 * Check whether connection should be accepted by MaxStartups. 842 * Returns 0 if the connection is accepted. If the connection is refused, 843 * returns 1 and attempts to send notification to client. 844 * Logs when the MaxStartups condition is entered or exited, and periodically 845 * while in that state. 846 */ 847 static int 848 drop_connection(int sock, int startups, int notify_pipe) 849 { 850 char *laddr, *raddr; 851 const char msg[] = "Exceeded MaxStartups\r\n"; 852 static time_t last_drop, first_drop; 853 static u_int ndropped; 854 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 855 time_t now; 856 857 now = monotime(); 858 if (!should_drop_connection(startups) && 859 srclimit_check_allow(sock, notify_pipe) == 1) { 860 if (last_drop != 0 && 861 startups < options.max_startups_begin - 1) { 862 /* XXX maybe need better hysteresis here */ 863 logit("exited MaxStartups throttling after %s, " 864 "%u connections dropped", 865 fmt_timeframe(now - first_drop), ndropped); 866 last_drop = 0; 867 } 868 return 0; 869 } 870 871 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 872 if (last_drop == 0) { 873 error("beginning MaxStartups throttling"); 874 drop_level = SYSLOG_LEVEL_INFO; 875 first_drop = now; 876 ndropped = 0; 877 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 878 /* Periodic logs */ 879 error("in MaxStartups throttling for %s, " 880 "%u connections dropped", 881 fmt_timeframe(now - first_drop), ndropped + 1); 882 drop_level = SYSLOG_LEVEL_INFO; 883 } 884 last_drop = now; 885 ndropped++; 886 887 laddr = get_local_ipaddr(sock); 888 raddr = get_peer_ipaddr(sock); 889 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 890 "past MaxStartups", startups, raddr, get_peer_port(sock), 891 laddr, get_local_port(sock)); 892 free(laddr); 893 free(raddr); 894 /* best-effort notification to client */ 895 (void)write(sock, msg, sizeof(msg) - 1); 896 return 1; 897 } 898 899 static void 900 usage(void) 901 { 902 fprintf(stderr, "%s, %s\n", SSH_RELEASE, SSH_OPENSSL_VERSION); 903 fprintf(stderr, 904 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 905 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 906 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 907 ); 908 exit(1); 909 } 910 911 static void 912 send_rexec_state(int fd, struct sshbuf *conf) 913 { 914 struct sshbuf *m = NULL, *inc = NULL; 915 struct include_item *item = NULL; 916 int r; 917 918 debug3_f("entering fd = %d config len %zu", fd, 919 sshbuf_len(conf)); 920 921 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 922 fatal_f("sshbuf_new failed"); 923 924 /* pack includes into a string */ 925 TAILQ_FOREACH(item, &includes, entry) { 926 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 927 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 928 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 929 fatal_fr(r, "compose includes"); 930 } 931 932 /* 933 * Protocol from reexec master to child: 934 * string configuration 935 * string included_files[] { 936 * string selector 937 * string filename 938 * string contents 939 * } 940 * string rng_seed (if required) 941 */ 942 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 943 (r = sshbuf_put_stringb(m, inc)) != 0) 944 fatal_fr(r, "compose config"); 945 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 946 rexec_send_rng_seed(m); 947 #endif 948 if (ssh_msg_send(fd, 0, m) == -1) 949 error_f("ssh_msg_send failed"); 950 951 sshbuf_free(m); 952 sshbuf_free(inc); 953 954 debug3_f("done"); 955 } 956 957 static void 958 recv_rexec_state(int fd, struct sshbuf *conf) 959 { 960 struct sshbuf *m, *inc; 961 u_char *cp, ver; 962 size_t len; 963 int r; 964 struct include_item *item; 965 966 debug3_f("entering fd = %d", fd); 967 968 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 969 fatal_f("sshbuf_new failed"); 970 if (ssh_msg_recv(fd, m) == -1) 971 fatal_f("ssh_msg_recv failed"); 972 if ((r = sshbuf_get_u8(m, &ver)) != 0) 973 fatal_fr(r, "parse version"); 974 if (ver != 0) 975 fatal_f("rexec version mismatch"); 976 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 977 (r = sshbuf_get_stringb(m, inc)) != 0) 978 fatal_fr(r, "parse config"); 979 980 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 981 rexec_recv_rng_seed(m); 982 #endif 983 984 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 985 fatal_fr(r, "sshbuf_put"); 986 987 while (sshbuf_len(inc) != 0) { 988 item = xcalloc(1, sizeof(*item)); 989 if ((item->contents = sshbuf_new()) == NULL) 990 fatal_f("sshbuf_new failed"); 991 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 992 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 993 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 994 fatal_fr(r, "parse includes"); 995 TAILQ_INSERT_TAIL(&includes, item, entry); 996 } 997 998 free(cp); 999 sshbuf_free(m); 1000 1001 debug3_f("done"); 1002 } 1003 1004 /* Accept a connection from inetd */ 1005 static void 1006 server_accept_inetd(int *sock_in, int *sock_out) 1007 { 1008 if (rexeced_flag) { 1009 close(REEXEC_CONFIG_PASS_FD); 1010 *sock_in = *sock_out = dup(STDIN_FILENO); 1011 } else { 1012 *sock_in = dup(STDIN_FILENO); 1013 *sock_out = dup(STDOUT_FILENO); 1014 } 1015 /* 1016 * We intentionally do not close the descriptors 0, 1, and 2 1017 * as our code for setting the descriptors won't work if 1018 * ttyfd happens to be one of those. 1019 */ 1020 if (stdfd_devnull(1, 1, !log_stderr) == -1) 1021 error_f("stdfd_devnull failed"); 1022 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1023 } 1024 1025 /* 1026 * Listen for TCP connections 1027 */ 1028 static void 1029 listen_on_addrs(struct listenaddr *la) 1030 { 1031 int ret, listen_sock; 1032 struct addrinfo *ai; 1033 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1034 1035 for (ai = la->addrs; ai; ai = ai->ai_next) { 1036 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1037 continue; 1038 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1039 fatal("Too many listen sockets. " 1040 "Enlarge MAX_LISTEN_SOCKS"); 1041 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1042 ntop, sizeof(ntop), strport, sizeof(strport), 1043 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1044 error("getnameinfo failed: %.100s", 1045 ssh_gai_strerror(ret)); 1046 continue; 1047 } 1048 /* Create socket for listening. */ 1049 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1050 ai->ai_protocol); 1051 if (listen_sock == -1) { 1052 /* kernel may not support ipv6 */ 1053 verbose("socket: %.100s", strerror(errno)); 1054 continue; 1055 } 1056 if (set_nonblock(listen_sock) == -1) { 1057 close(listen_sock); 1058 continue; 1059 } 1060 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1061 verbose("socket: CLOEXEC: %s", strerror(errno)); 1062 close(listen_sock); 1063 continue; 1064 } 1065 /* Socket options */ 1066 set_reuseaddr(listen_sock); 1067 if (la->rdomain != NULL && 1068 set_rdomain(listen_sock, la->rdomain) == -1) { 1069 close(listen_sock); 1070 continue; 1071 } 1072 1073 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1074 if (ai->ai_family == AF_INET6) 1075 sock_set_v6only(listen_sock); 1076 1077 debug("Bind to port %s on %s.", strport, ntop); 1078 1079 /* Bind the socket to the desired port. */ 1080 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1081 error("Bind to port %s on %s failed: %.200s.", 1082 strport, ntop, strerror(errno)); 1083 close(listen_sock); 1084 continue; 1085 } 1086 listen_socks[num_listen_socks] = listen_sock; 1087 num_listen_socks++; 1088 1089 /* Start listening on the port. */ 1090 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1091 fatal("listen on [%s]:%s: %.100s", 1092 ntop, strport, strerror(errno)); 1093 logit("Server listening on %s port %s%s%s.", 1094 ntop, strport, 1095 la->rdomain == NULL ? "" : " rdomain ", 1096 la->rdomain == NULL ? "" : la->rdomain); 1097 } 1098 } 1099 1100 static void 1101 server_listen(void) 1102 { 1103 u_int i; 1104 1105 /* Initialise per-source limit tracking. */ 1106 srclimit_init(options.max_startups, options.per_source_max_startups, 1107 options.per_source_masklen_ipv4, options.per_source_masklen_ipv6); 1108 1109 for (i = 0; i < options.num_listen_addrs; i++) { 1110 listen_on_addrs(&options.listen_addrs[i]); 1111 freeaddrinfo(options.listen_addrs[i].addrs); 1112 free(options.listen_addrs[i].rdomain); 1113 memset(&options.listen_addrs[i], 0, 1114 sizeof(options.listen_addrs[i])); 1115 } 1116 free(options.listen_addrs); 1117 options.listen_addrs = NULL; 1118 options.num_listen_addrs = 0; 1119 1120 if (!num_listen_socks) 1121 fatal("Cannot bind any address."); 1122 } 1123 1124 /* 1125 * The main TCP accept loop. Note that, for the non-debug case, returns 1126 * from this function are in a forked subprocess. 1127 */ 1128 static void 1129 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1130 { 1131 struct pollfd *pfd = NULL; 1132 int i, j, ret, npfd; 1133 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1134 int startup_p[2] = { -1 , -1 }, *startup_pollfd; 1135 char c = 0; 1136 struct sockaddr_storage from; 1137 socklen_t fromlen; 1138 pid_t pid; 1139 u_char rnd[256]; 1140 sigset_t nsigset, osigset; 1141 1142 /* pipes connected to unauthenticated child sshd processes */ 1143 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1144 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1145 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 1146 for (i = 0; i < options.max_startups; i++) 1147 startup_pipes[i] = -1; 1148 1149 /* 1150 * Prepare signal mask that we use to block signals that might set 1151 * received_sigterm or received_sighup, so that we are guaranteed 1152 * to immediately wake up the ppoll if a signal is received after 1153 * the flag is checked. 1154 */ 1155 sigemptyset(&nsigset); 1156 sigaddset(&nsigset, SIGHUP); 1157 sigaddset(&nsigset, SIGCHLD); 1158 sigaddset(&nsigset, SIGTERM); 1159 sigaddset(&nsigset, SIGQUIT); 1160 1161 /* sized for worst-case */ 1162 pfd = xcalloc(num_listen_socks + options.max_startups, 1163 sizeof(struct pollfd)); 1164 1165 /* 1166 * Stay listening for connections until the system crashes or 1167 * the daemon is killed with a signal. 1168 */ 1169 for (;;) { 1170 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 1171 if (received_sigterm) { 1172 logit("Received signal %d; terminating.", 1173 (int) received_sigterm); 1174 close_listen_socks(); 1175 if (options.pid_file != NULL) 1176 unlink(options.pid_file); 1177 exit(received_sigterm == SIGTERM ? 0 : 255); 1178 } 1179 if (ostartups != startups) { 1180 setproctitle("%s [listener] %d of %d-%d startups", 1181 listener_proctitle, startups, 1182 options.max_startups_begin, options.max_startups); 1183 ostartups = startups; 1184 } 1185 if (received_sighup) { 1186 if (!lameduck) { 1187 debug("Received SIGHUP; waiting for children"); 1188 close_listen_socks(); 1189 lameduck = 1; 1190 } 1191 if (listening <= 0) { 1192 sigprocmask(SIG_SETMASK, &osigset, NULL); 1193 sighup_restart(); 1194 } 1195 } 1196 1197 for (i = 0; i < num_listen_socks; i++) { 1198 pfd[i].fd = listen_socks[i]; 1199 pfd[i].events = POLLIN; 1200 } 1201 npfd = num_listen_socks; 1202 for (i = 0; i < options.max_startups; i++) { 1203 startup_pollfd[i] = -1; 1204 if (startup_pipes[i] != -1) { 1205 pfd[npfd].fd = startup_pipes[i]; 1206 pfd[npfd].events = POLLIN; 1207 startup_pollfd[i] = npfd++; 1208 } 1209 } 1210 1211 /* Wait until a connection arrives or a child exits. */ 1212 ret = ppoll(pfd, npfd, NULL, &osigset); 1213 if (ret == -1 && errno != EINTR) { 1214 error("ppoll: %.100s", strerror(errno)); 1215 if (errno == EINVAL) 1216 cleanup_exit(1); /* can't recover */ 1217 } 1218 sigprocmask(SIG_SETMASK, &osigset, NULL); 1219 if (ret == -1) 1220 continue; 1221 1222 for (i = 0; i < options.max_startups; i++) { 1223 if (startup_pipes[i] == -1 || 1224 startup_pollfd[i] == -1 || 1225 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 1226 continue; 1227 switch (read(startup_pipes[i], &c, sizeof(c))) { 1228 case -1: 1229 if (errno == EINTR || errno == EAGAIN) 1230 continue; 1231 if (errno != EPIPE) { 1232 error_f("startup pipe %d (fd=%d): " 1233 "read %s", i, startup_pipes[i], 1234 strerror(errno)); 1235 } 1236 /* FALLTHROUGH */ 1237 case 0: 1238 /* child exited or completed auth */ 1239 close(startup_pipes[i]); 1240 srclimit_done(startup_pipes[i]); 1241 startup_pipes[i] = -1; 1242 startups--; 1243 if (startup_flags[i]) 1244 listening--; 1245 break; 1246 case 1: 1247 /* child has finished preliminaries */ 1248 if (startup_flags[i]) { 1249 listening--; 1250 startup_flags[i] = 0; 1251 } 1252 break; 1253 } 1254 } 1255 for (i = 0; i < num_listen_socks; i++) { 1256 if (!(pfd[i].revents & POLLIN)) 1257 continue; 1258 fromlen = sizeof(from); 1259 *newsock = accept(listen_socks[i], 1260 (struct sockaddr *)&from, &fromlen); 1261 if (*newsock == -1) { 1262 if (errno != EINTR && errno != EWOULDBLOCK && 1263 errno != ECONNABORTED && errno != EAGAIN) 1264 error("accept: %.100s", 1265 strerror(errno)); 1266 if (errno == EMFILE || errno == ENFILE) 1267 usleep(100 * 1000); 1268 continue; 1269 } 1270 if (unset_nonblock(*newsock) == -1) { 1271 close(*newsock); 1272 continue; 1273 } 1274 if (pipe(startup_p) == -1) { 1275 error_f("pipe(startup_p): %s", strerror(errno)); 1276 close(*newsock); 1277 continue; 1278 } 1279 if (drop_connection(*newsock, startups, startup_p[0])) { 1280 close(*newsock); 1281 close(startup_p[0]); 1282 close(startup_p[1]); 1283 continue; 1284 } 1285 1286 if (rexec_flag && socketpair(AF_UNIX, 1287 SOCK_STREAM, 0, config_s) == -1) { 1288 error("reexec socketpair: %s", 1289 strerror(errno)); 1290 close(*newsock); 1291 close(startup_p[0]); 1292 close(startup_p[1]); 1293 continue; 1294 } 1295 1296 for (j = 0; j < options.max_startups; j++) 1297 if (startup_pipes[j] == -1) { 1298 startup_pipes[j] = startup_p[0]; 1299 startups++; 1300 startup_flags[j] = 1; 1301 break; 1302 } 1303 1304 /* 1305 * Got connection. Fork a child to handle it, unless 1306 * we are in debugging mode. 1307 */ 1308 if (debug_flag) { 1309 /* 1310 * In debugging mode. Close the listening 1311 * socket, and start processing the 1312 * connection without forking. 1313 */ 1314 debug("Server will not fork when running in debugging mode."); 1315 close_listen_socks(); 1316 *sock_in = *newsock; 1317 *sock_out = *newsock; 1318 close(startup_p[0]); 1319 close(startup_p[1]); 1320 startup_pipe = -1; 1321 pid = getpid(); 1322 if (rexec_flag) { 1323 send_rexec_state(config_s[0], cfg); 1324 close(config_s[0]); 1325 } 1326 free(pfd); 1327 return; 1328 } 1329 1330 /* 1331 * Normal production daemon. Fork, and have 1332 * the child process the connection. The 1333 * parent continues listening. 1334 */ 1335 platform_pre_fork(); 1336 listening++; 1337 if ((pid = fork()) == 0) { 1338 /* 1339 * Child. Close the listening and 1340 * max_startup sockets. Start using 1341 * the accepted socket. Reinitialize 1342 * logging (since our pid has changed). 1343 * We return from this function to handle 1344 * the connection. 1345 */ 1346 platform_post_fork_child(); 1347 startup_pipe = startup_p[1]; 1348 close_startup_pipes(); 1349 close_listen_socks(); 1350 *sock_in = *newsock; 1351 *sock_out = *newsock; 1352 log_init(__progname, 1353 options.log_level, 1354 options.log_facility, 1355 log_stderr); 1356 if (rexec_flag) 1357 close(config_s[0]); 1358 else { 1359 /* 1360 * Signal parent that the preliminaries 1361 * for this child are complete. For the 1362 * re-exec case, this happens after the 1363 * child has received the rexec state 1364 * from the server. 1365 */ 1366 (void)atomicio(vwrite, startup_pipe, 1367 "\0", 1); 1368 } 1369 free(pfd); 1370 return; 1371 } 1372 1373 /* Parent. Stay in the loop. */ 1374 platform_post_fork_parent(pid); 1375 if (pid == -1) 1376 error("fork: %.100s", strerror(errno)); 1377 else 1378 debug("Forked child %ld.", (long)pid); 1379 1380 close(startup_p[1]); 1381 1382 if (rexec_flag) { 1383 close(config_s[1]); 1384 send_rexec_state(config_s[0], cfg); 1385 close(config_s[0]); 1386 } 1387 close(*newsock); 1388 1389 /* 1390 * Ensure that our random state differs 1391 * from that of the child 1392 */ 1393 arc4random_stir(); 1394 arc4random_buf(rnd, sizeof(rnd)); 1395 #ifdef WITH_OPENSSL 1396 RAND_seed(rnd, sizeof(rnd)); 1397 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1398 fatal("%s: RAND_bytes failed", __func__); 1399 #endif 1400 explicit_bzero(rnd, sizeof(rnd)); 1401 } 1402 } 1403 } 1404 1405 /* 1406 * If IP options are supported, make sure there are none (log and 1407 * return an error if any are found). Basically we are worried about 1408 * source routing; it can be used to pretend you are somebody 1409 * (ip-address) you are not. That itself may be "almost acceptable" 1410 * under certain circumstances, but rhosts authentication is useless 1411 * if source routing is accepted. Notice also that if we just dropped 1412 * source routing here, the other side could use IP spoofing to do 1413 * rest of the interaction and could still bypass security. So we 1414 * exit here if we detect any IP options. 1415 */ 1416 static void 1417 check_ip_options(struct ssh *ssh) 1418 { 1419 #ifdef IP_OPTIONS 1420 int sock_in = ssh_packet_get_connection_in(ssh); 1421 struct sockaddr_storage from; 1422 u_char opts[200]; 1423 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1424 char text[sizeof(opts) * 3 + 1]; 1425 1426 memset(&from, 0, sizeof(from)); 1427 if (getpeername(sock_in, (struct sockaddr *)&from, 1428 &fromlen) == -1) 1429 return; 1430 if (from.ss_family != AF_INET) 1431 return; 1432 /* XXX IPv6 options? */ 1433 1434 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1435 &option_size) >= 0 && option_size != 0) { 1436 text[0] = '\0'; 1437 for (i = 0; i < option_size; i++) 1438 snprintf(text + i*3, sizeof(text) - i*3, 1439 " %2.2x", opts[i]); 1440 fatal("Connection from %.100s port %d with IP opts: %.800s", 1441 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1442 } 1443 return; 1444 #endif /* IP_OPTIONS */ 1445 } 1446 1447 /* Set the routing domain for this process */ 1448 static void 1449 set_process_rdomain(struct ssh *ssh, const char *name) 1450 { 1451 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) 1452 if (name == NULL) 1453 return; /* default */ 1454 1455 if (strcmp(name, "%D") == 0) { 1456 /* "expands" to routing domain of connection */ 1457 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1458 return; 1459 } 1460 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ 1461 return sys_set_process_rdomain(name); 1462 #elif defined(__OpenBSD__) 1463 int rtable, ortable = getrtable(); 1464 const char *errstr; 1465 1466 if (name == NULL) 1467 return; /* default */ 1468 1469 if (strcmp(name, "%D") == 0) { 1470 /* "expands" to routing domain of connection */ 1471 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1472 return; 1473 } 1474 1475 rtable = (int)strtonum(name, 0, 255, &errstr); 1476 if (errstr != NULL) /* Shouldn't happen */ 1477 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1478 if (rtable != ortable && setrtable(rtable) != 0) 1479 fatal("Unable to set routing domain %d: %s", 1480 rtable, strerror(errno)); 1481 debug_f("set routing domain %d (was %d)", rtable, ortable); 1482 #else /* defined(__OpenBSD__) */ 1483 fatal("Unable to set routing domain: not supported in this platform"); 1484 #endif 1485 } 1486 1487 static void 1488 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1489 struct sshkey *key) 1490 { 1491 static struct ssh_digest_ctx *ctx; 1492 u_char *hash; 1493 size_t len; 1494 struct sshbuf *buf; 1495 int r; 1496 1497 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1498 fatal_f("ssh_digest_start"); 1499 if (key == NULL) { /* finalize */ 1500 /* add server config in case we are using agent for host keys */ 1501 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1502 sshbuf_len(server_cfg)) != 0) 1503 fatal_f("ssh_digest_update"); 1504 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1505 hash = xmalloc(len); 1506 if (ssh_digest_final(ctx, hash, len) != 0) 1507 fatal_f("ssh_digest_final"); 1508 options.timing_secret = PEEK_U64(hash); 1509 freezero(hash, len); 1510 ssh_digest_free(ctx); 1511 ctx = NULL; 1512 return; 1513 } 1514 if ((buf = sshbuf_new()) == NULL) 1515 fatal_f("could not allocate buffer"); 1516 if ((r = sshkey_private_serialize(key, buf)) != 0) 1517 fatal_fr(r, "decode key"); 1518 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1519 fatal_f("ssh_digest_update"); 1520 sshbuf_reset(buf); 1521 sshbuf_free(buf); 1522 } 1523 1524 static char * 1525 prepare_proctitle(int ac, char **av) 1526 { 1527 char *ret = NULL; 1528 int i; 1529 1530 for (i = 0; i < ac; i++) 1531 xextendf(&ret, " ", "%s", av[i]); 1532 return ret; 1533 } 1534 1535 /* 1536 * Main program for the daemon. 1537 */ 1538 int 1539 main(int ac, char **av) 1540 { 1541 struct ssh *ssh = NULL; 1542 extern char *optarg; 1543 extern int optind; 1544 int r, opt, on = 1, already_daemon, remote_port; 1545 int sock_in = -1, sock_out = -1, newsock = -1; 1546 const char *remote_ip, *rdomain; 1547 char *fp, *line, *laddr, *logfile = NULL; 1548 int config_s[2] = { -1 , -1 }; 1549 u_int i, j; 1550 u_int64_t ibytes, obytes; 1551 mode_t new_umask; 1552 struct sshkey *key; 1553 struct sshkey *pubkey; 1554 int keytype; 1555 Authctxt *authctxt; 1556 struct connection_info *connection_info = NULL; 1557 1558 #ifdef HAVE_SECUREWARE 1559 (void)set_auth_parameters(ac, av); 1560 #endif 1561 __progname = ssh_get_progname(av[0]); 1562 1563 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1564 saved_argc = ac; 1565 rexec_argc = ac; 1566 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1567 for (i = 0; (int)i < ac; i++) 1568 saved_argv[i] = xstrdup(av[i]); 1569 saved_argv[i] = NULL; 1570 1571 #ifndef HAVE_SETPROCTITLE 1572 /* Prepare for later setproctitle emulation */ 1573 compat_init_setproctitle(ac, av); 1574 av = saved_argv; 1575 #endif 1576 1577 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1578 debug("setgroups(): %.200s", strerror(errno)); 1579 1580 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1581 sanitise_stdfd(); 1582 1583 seed_rng(); 1584 1585 /* Initialize configuration options to their default values. */ 1586 initialize_server_options(&options); 1587 1588 /* Parse command-line arguments. */ 1589 while ((opt = getopt(ac, av, 1590 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1591 switch (opt) { 1592 case '4': 1593 options.address_family = AF_INET; 1594 break; 1595 case '6': 1596 options.address_family = AF_INET6; 1597 break; 1598 case 'f': 1599 config_file_name = optarg; 1600 break; 1601 case 'c': 1602 servconf_add_hostcert("[command-line]", 0, 1603 &options, optarg); 1604 break; 1605 case 'd': 1606 if (debug_flag == 0) { 1607 debug_flag = 1; 1608 options.log_level = SYSLOG_LEVEL_DEBUG1; 1609 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1610 options.log_level++; 1611 break; 1612 case 'D': 1613 no_daemon_flag = 1; 1614 break; 1615 case 'E': 1616 logfile = optarg; 1617 /* FALLTHROUGH */ 1618 case 'e': 1619 log_stderr = 1; 1620 break; 1621 case 'i': 1622 inetd_flag = 1; 1623 break; 1624 case 'r': 1625 rexec_flag = 0; 1626 break; 1627 case 'R': 1628 rexeced_flag = 1; 1629 inetd_flag = 1; 1630 break; 1631 case 'Q': 1632 /* ignored */ 1633 break; 1634 case 'q': 1635 options.log_level = SYSLOG_LEVEL_QUIET; 1636 break; 1637 case 'b': 1638 /* protocol 1, ignored */ 1639 break; 1640 case 'p': 1641 options.ports_from_cmdline = 1; 1642 if (options.num_ports >= MAX_PORTS) { 1643 fprintf(stderr, "too many ports.\n"); 1644 exit(1); 1645 } 1646 options.ports[options.num_ports++] = a2port(optarg); 1647 if (options.ports[options.num_ports-1] <= 0) { 1648 fprintf(stderr, "Bad port number.\n"); 1649 exit(1); 1650 } 1651 break; 1652 case 'g': 1653 if ((options.login_grace_time = convtime(optarg)) == -1) { 1654 fprintf(stderr, "Invalid login grace time.\n"); 1655 exit(1); 1656 } 1657 break; 1658 case 'k': 1659 /* protocol 1, ignored */ 1660 break; 1661 case 'h': 1662 servconf_add_hostkey("[command-line]", 0, 1663 &options, optarg, 1); 1664 break; 1665 case 't': 1666 test_flag = 1; 1667 break; 1668 case 'T': 1669 test_flag = 2; 1670 break; 1671 case 'C': 1672 connection_info = get_connection_info(ssh, 0, 0); 1673 if (parse_server_match_testspec(connection_info, 1674 optarg) == -1) 1675 exit(1); 1676 break; 1677 case 'u': 1678 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1679 if (utmp_len > HOST_NAME_MAX+1) { 1680 fprintf(stderr, "Invalid utmp length.\n"); 1681 exit(1); 1682 } 1683 break; 1684 case 'o': 1685 line = xstrdup(optarg); 1686 if (process_server_config_line(&options, line, 1687 "command-line", 0, NULL, NULL, &includes) != 0) 1688 exit(1); 1689 free(line); 1690 break; 1691 case '?': 1692 default: 1693 usage(); 1694 break; 1695 } 1696 } 1697 if (rexeced_flag || inetd_flag) 1698 rexec_flag = 0; 1699 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1700 fatal("sshd re-exec requires execution with an absolute path"); 1701 if (rexeced_flag) 1702 closefrom(REEXEC_MIN_FREE_FD); 1703 else 1704 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1705 1706 /* If requested, redirect the logs to the specified logfile. */ 1707 if (logfile != NULL) 1708 log_redirect_stderr_to(logfile); 1709 /* 1710 * Force logging to stderr until we have loaded the private host 1711 * key (unless started from inetd) 1712 */ 1713 log_init(__progname, 1714 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1715 SYSLOG_LEVEL_INFO : options.log_level, 1716 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1717 SYSLOG_FACILITY_AUTH : options.log_facility, 1718 log_stderr || !inetd_flag || debug_flag); 1719 1720 /* 1721 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1722 * root's environment 1723 */ 1724 if (getenv("KRB5CCNAME") != NULL) 1725 (void) unsetenv("KRB5CCNAME"); 1726 1727 sensitive_data.have_ssh2_key = 0; 1728 1729 /* 1730 * If we're not doing an extended test do not silently ignore connection 1731 * test params. 1732 */ 1733 if (test_flag < 2 && connection_info != NULL) 1734 fatal("Config test connection parameter (-C) provided without " 1735 "test mode (-T)"); 1736 1737 /* Fetch our configuration */ 1738 if ((cfg = sshbuf_new()) == NULL) 1739 fatal_f("sshbuf_new failed"); 1740 if (rexeced_flag) { 1741 setproctitle("%s", "[rexeced]"); 1742 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1743 if (!debug_flag) { 1744 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1745 close(REEXEC_STARTUP_PIPE_FD); 1746 /* 1747 * Signal parent that this child is at a point where 1748 * they can go away if they have a SIGHUP pending. 1749 */ 1750 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1751 } 1752 } else if (strcasecmp(config_file_name, "none") != 0) 1753 load_server_config(config_file_name, cfg); 1754 1755 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1756 cfg, &includes, NULL, rexeced_flag); 1757 1758 #ifdef WITH_OPENSSL 1759 if (options.moduli_file != NULL) 1760 dh_set_moduli_file(options.moduli_file); 1761 #endif 1762 1763 /* Fill in default values for those options not explicitly set. */ 1764 fill_default_server_options(&options); 1765 1766 /* Check that options are sensible */ 1767 if (options.authorized_keys_command_user == NULL && 1768 (options.authorized_keys_command != NULL && 1769 strcasecmp(options.authorized_keys_command, "none") != 0)) 1770 fatal("AuthorizedKeysCommand set without " 1771 "AuthorizedKeysCommandUser"); 1772 if (options.authorized_principals_command_user == NULL && 1773 (options.authorized_principals_command != NULL && 1774 strcasecmp(options.authorized_principals_command, "none") != 0)) 1775 fatal("AuthorizedPrincipalsCommand set without " 1776 "AuthorizedPrincipalsCommandUser"); 1777 1778 /* 1779 * Check whether there is any path through configured auth methods. 1780 * Unfortunately it is not possible to verify this generally before 1781 * daemonisation in the presence of Match block, but this catches 1782 * and warns for trivial misconfigurations that could break login. 1783 */ 1784 if (options.num_auth_methods != 0) { 1785 for (i = 0; i < options.num_auth_methods; i++) { 1786 if (auth2_methods_valid(options.auth_methods[i], 1787 1) == 0) 1788 break; 1789 } 1790 if (i >= options.num_auth_methods) 1791 fatal("AuthenticationMethods cannot be satisfied by " 1792 "enabled authentication methods"); 1793 } 1794 1795 /* Check that there are no remaining arguments. */ 1796 if (optind < ac) { 1797 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1798 exit(1); 1799 } 1800 1801 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1802 1803 /* Store privilege separation user for later use if required. */ 1804 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); 1805 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1806 if (privsep_chroot || options.kerberos_authentication) 1807 fatal("Privilege separation user %s does not exist", 1808 SSH_PRIVSEP_USER); 1809 } else { 1810 privsep_pw = pwcopy(privsep_pw); 1811 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); 1812 privsep_pw->pw_passwd = xstrdup("*"); 1813 } 1814 endpwent(); 1815 1816 /* load host keys */ 1817 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1818 sizeof(struct sshkey *)); 1819 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1820 sizeof(struct sshkey *)); 1821 1822 if (options.host_key_agent) { 1823 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1824 setenv(SSH_AUTHSOCKET_ENV_NAME, 1825 options.host_key_agent, 1); 1826 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1827 have_agent = 1; 1828 else 1829 error_r(r, "Could not connect to agent \"%s\"", 1830 options.host_key_agent); 1831 } 1832 1833 for (i = 0; i < options.num_host_key_files; i++) { 1834 int ll = options.host_key_file_userprovided[i] ? 1835 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1836 1837 if (options.host_key_files[i] == NULL) 1838 continue; 1839 if ((r = sshkey_load_private(options.host_key_files[i], "", 1840 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1841 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1842 options.host_key_files[i]); 1843 if (sshkey_is_sk(key) && 1844 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1845 debug("host key %s requires user presence, ignoring", 1846 options.host_key_files[i]); 1847 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1848 } 1849 if (r == 0 && key != NULL && 1850 (r = sshkey_shield_private(key)) != 0) { 1851 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1852 options.host_key_files[i]); 1853 sshkey_free(key); 1854 key = NULL; 1855 } 1856 if ((r = sshkey_load_public(options.host_key_files[i], 1857 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1858 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1859 options.host_key_files[i]); 1860 if (pubkey != NULL && key != NULL) { 1861 if (!sshkey_equal(pubkey, key)) { 1862 error("Public key for %s does not match " 1863 "private key", options.host_key_files[i]); 1864 sshkey_free(pubkey); 1865 pubkey = NULL; 1866 } 1867 } 1868 if (pubkey == NULL && key != NULL) { 1869 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1870 fatal_r(r, "Could not demote key: \"%s\"", 1871 options.host_key_files[i]); 1872 } 1873 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1874 options.required_rsa_size)) != 0) { 1875 error_fr(r, "Host key %s", options.host_key_files[i]); 1876 sshkey_free(pubkey); 1877 sshkey_free(key); 1878 continue; 1879 } 1880 sensitive_data.host_keys[i] = key; 1881 sensitive_data.host_pubkeys[i] = pubkey; 1882 1883 if (key == NULL && pubkey != NULL && have_agent) { 1884 debug("will rely on agent for hostkey %s", 1885 options.host_key_files[i]); 1886 keytype = pubkey->type; 1887 } else if (key != NULL) { 1888 keytype = key->type; 1889 accumulate_host_timing_secret(cfg, key); 1890 } else { 1891 do_log2(ll, "Unable to load host key: %s", 1892 options.host_key_files[i]); 1893 sensitive_data.host_keys[i] = NULL; 1894 sensitive_data.host_pubkeys[i] = NULL; 1895 continue; 1896 } 1897 1898 switch (keytype) { 1899 case KEY_RSA: 1900 case KEY_DSA: 1901 case KEY_ECDSA: 1902 case KEY_ED25519: 1903 case KEY_ECDSA_SK: 1904 case KEY_ED25519_SK: 1905 case KEY_XMSS: 1906 if (have_agent || key != NULL) 1907 sensitive_data.have_ssh2_key = 1; 1908 break; 1909 } 1910 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1911 SSH_FP_DEFAULT)) == NULL) 1912 fatal("sshkey_fingerprint failed"); 1913 debug("%s host key #%d: %s %s", 1914 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1915 free(fp); 1916 } 1917 accumulate_host_timing_secret(cfg, NULL); 1918 if (!sensitive_data.have_ssh2_key) { 1919 logit("sshd: no hostkeys available -- exiting."); 1920 exit(1); 1921 } 1922 1923 /* 1924 * Load certificates. They are stored in an array at identical 1925 * indices to the public keys that they relate to. 1926 */ 1927 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1928 sizeof(struct sshkey *)); 1929 for (i = 0; i < options.num_host_key_files; i++) 1930 sensitive_data.host_certificates[i] = NULL; 1931 1932 for (i = 0; i < options.num_host_cert_files; i++) { 1933 if (options.host_cert_files[i] == NULL) 1934 continue; 1935 if ((r = sshkey_load_public(options.host_cert_files[i], 1936 &key, NULL)) != 0) { 1937 error_r(r, "Could not load host certificate \"%s\"", 1938 options.host_cert_files[i]); 1939 continue; 1940 } 1941 if (!sshkey_is_cert(key)) { 1942 error("Certificate file is not a certificate: %s", 1943 options.host_cert_files[i]); 1944 sshkey_free(key); 1945 continue; 1946 } 1947 /* Find matching private key */ 1948 for (j = 0; j < options.num_host_key_files; j++) { 1949 if (sshkey_equal_public(key, 1950 sensitive_data.host_pubkeys[j])) { 1951 sensitive_data.host_certificates[j] = key; 1952 break; 1953 } 1954 } 1955 if (j >= options.num_host_key_files) { 1956 error("No matching private key for certificate: %s", 1957 options.host_cert_files[i]); 1958 sshkey_free(key); 1959 continue; 1960 } 1961 sensitive_data.host_certificates[j] = key; 1962 debug("host certificate: #%u type %d %s", j, key->type, 1963 sshkey_type(key)); 1964 } 1965 1966 if (privsep_chroot) { 1967 struct stat st; 1968 1969 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1970 (S_ISDIR(st.st_mode) == 0)) 1971 fatal("Missing privilege separation directory: %s", 1972 _PATH_PRIVSEP_CHROOT_DIR); 1973 1974 #ifdef HAVE_CYGWIN 1975 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1976 (st.st_uid != getuid () || 1977 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1978 #else 1979 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1980 #endif 1981 fatal("%s must be owned by root and not group or " 1982 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1983 } 1984 1985 if (test_flag > 1) { 1986 /* 1987 * If no connection info was provided by -C then use 1988 * use a blank one that will cause no predicate to match. 1989 */ 1990 if (connection_info == NULL) 1991 connection_info = get_connection_info(ssh, 0, 0); 1992 connection_info->test = 1; 1993 parse_server_match_config(&options, &includes, connection_info); 1994 dump_config(&options); 1995 } 1996 1997 /* Configuration looks good, so exit if in test mode. */ 1998 if (test_flag) 1999 exit(0); 2000 2001 /* 2002 * Clear out any supplemental groups we may have inherited. This 2003 * prevents inadvertent creation of files with bad modes (in the 2004 * portable version at least, it's certainly possible for PAM 2005 * to create a file, and we can't control the code in every 2006 * module which might be used). 2007 */ 2008 if (setgroups(0, NULL) < 0) 2009 debug("setgroups() failed: %.200s", strerror(errno)); 2010 2011 if (rexec_flag) { 2012 if (rexec_argc < 0) 2013 fatal("rexec_argc %d < 0", rexec_argc); 2014 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 2015 for (i = 0; i < (u_int)rexec_argc; i++) { 2016 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 2017 rexec_argv[i] = saved_argv[i]; 2018 } 2019 rexec_argv[rexec_argc] = "-R"; 2020 rexec_argv[rexec_argc + 1] = NULL; 2021 } 2022 listener_proctitle = prepare_proctitle(ac, av); 2023 2024 /* Ensure that umask disallows at least group and world write */ 2025 new_umask = umask(0077) | 0022; 2026 (void) umask(new_umask); 2027 2028 /* Initialize the log (it is reinitialized below in case we forked). */ 2029 if (debug_flag && (!inetd_flag || rexeced_flag)) 2030 log_stderr = 1; 2031 log_init(__progname, options.log_level, 2032 options.log_facility, log_stderr); 2033 for (i = 0; i < options.num_log_verbose; i++) 2034 log_verbose_add(options.log_verbose[i]); 2035 2036 /* 2037 * If not in debugging mode, not started from inetd and not already 2038 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 2039 * terminal, and fork. The original process exits. 2040 */ 2041 already_daemon = daemonized(); 2042 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 2043 2044 if (daemon(0, 0) == -1) 2045 fatal("daemon() failed: %.200s", strerror(errno)); 2046 2047 disconnect_controlling_tty(); 2048 } 2049 /* Reinitialize the log (because of the fork above). */ 2050 log_init(__progname, options.log_level, options.log_facility, log_stderr); 2051 2052 /* 2053 * Chdir to the root directory so that the current disk can be 2054 * unmounted if desired. 2055 */ 2056 if (chdir("/") == -1) 2057 error("chdir(\"/\"): %s", strerror(errno)); 2058 2059 /* ignore SIGPIPE */ 2060 ssh_signal(SIGPIPE, SIG_IGN); 2061 2062 /* Get a connection, either from inetd or a listening TCP socket */ 2063 if (inetd_flag) { 2064 server_accept_inetd(&sock_in, &sock_out); 2065 } else { 2066 platform_pre_listen(); 2067 server_listen(); 2068 2069 ssh_signal(SIGHUP, sighup_handler); 2070 ssh_signal(SIGCHLD, main_sigchld_handler); 2071 ssh_signal(SIGTERM, sigterm_handler); 2072 ssh_signal(SIGQUIT, sigterm_handler); 2073 2074 /* 2075 * Write out the pid file after the sigterm handler 2076 * is setup and the listen sockets are bound 2077 */ 2078 if (options.pid_file != NULL && !debug_flag) { 2079 FILE *f = fopen(options.pid_file, "w"); 2080 2081 if (f == NULL) { 2082 error("Couldn't create pid file \"%s\": %s", 2083 options.pid_file, strerror(errno)); 2084 } else { 2085 fprintf(f, "%ld\n", (long) getpid()); 2086 fclose(f); 2087 } 2088 } 2089 2090 /* Accept a connection and return in a forked child */ 2091 server_accept_loop(&sock_in, &sock_out, 2092 &newsock, config_s); 2093 } 2094 2095 /* This is the child processing a new connection. */ 2096 setproctitle("%s", "[accepted]"); 2097 2098 /* 2099 * Create a new session and process group since the 4.4BSD 2100 * setlogin() affects the entire process group. We don't 2101 * want the child to be able to affect the parent. 2102 */ 2103 if (!debug_flag && !inetd_flag && setsid() == -1) 2104 error("setsid: %.100s", strerror(errno)); 2105 2106 if (rexec_flag) { 2107 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2108 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2109 dup2(newsock, STDIN_FILENO); 2110 dup2(STDIN_FILENO, STDOUT_FILENO); 2111 if (startup_pipe == -1) 2112 close(REEXEC_STARTUP_PIPE_FD); 2113 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2114 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2115 close(startup_pipe); 2116 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2117 } 2118 2119 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2120 close(config_s[1]); 2121 2122 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 2123 execv(rexec_argv[0], rexec_argv); 2124 2125 /* Reexec has failed, fall back and continue */ 2126 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2127 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2128 log_init(__progname, options.log_level, 2129 options.log_facility, log_stderr); 2130 2131 /* Clean up fds */ 2132 close(REEXEC_CONFIG_PASS_FD); 2133 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2134 if (stdfd_devnull(1, 1, 0) == -1) 2135 error_f("stdfd_devnull failed"); 2136 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2137 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2138 } 2139 2140 /* Executed child processes don't need these. */ 2141 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2142 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2143 2144 /* We will not restart on SIGHUP since it no longer makes sense. */ 2145 ssh_signal(SIGALRM, SIG_DFL); 2146 ssh_signal(SIGHUP, SIG_DFL); 2147 ssh_signal(SIGTERM, SIG_DFL); 2148 ssh_signal(SIGQUIT, SIG_DFL); 2149 ssh_signal(SIGCHLD, SIG_DFL); 2150 ssh_signal(SIGINT, SIG_DFL); 2151 2152 /* 2153 * Register our connection. This turns encryption off because we do 2154 * not have a key. 2155 */ 2156 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2157 fatal("Unable to create connection"); 2158 the_active_state = ssh; 2159 ssh_packet_set_server(ssh); 2160 2161 check_ip_options(ssh); 2162 2163 /* Prepare the channels layer */ 2164 channel_init_channels(ssh); 2165 channel_set_af(ssh, options.address_family); 2166 process_permitopen(ssh, &options); 2167 2168 /* Set SO_KEEPALIVE if requested. */ 2169 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2170 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2171 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2172 2173 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2174 debug("ssh_remote_port failed"); 2175 cleanup_exit(255); 2176 } 2177 2178 if (options.routing_domain != NULL) 2179 set_process_rdomain(ssh, options.routing_domain); 2180 2181 /* 2182 * The rest of the code depends on the fact that 2183 * ssh_remote_ipaddr() caches the remote ip, even if 2184 * the socket goes away. 2185 */ 2186 remote_ip = ssh_remote_ipaddr(ssh); 2187 2188 #ifdef SSH_AUDIT_EVENTS 2189 audit_connection_from(remote_ip, remote_port); 2190 #endif 2191 2192 rdomain = ssh_packet_rdomain_in(ssh); 2193 2194 /* Log the connection. */ 2195 laddr = get_local_ipaddr(sock_in); 2196 verbose("Connection from %s port %d on %s port %d%s%s%s", 2197 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2198 rdomain == NULL ? "" : " rdomain \"", 2199 rdomain == NULL ? "" : rdomain, 2200 rdomain == NULL ? "" : "\""); 2201 free(laddr); 2202 2203 /* 2204 * We don't want to listen forever unless the other side 2205 * successfully authenticates itself. So we set up an alarm which is 2206 * cleared after successful authentication. A limit of zero 2207 * indicates no limit. Note that we don't set the alarm in debugging 2208 * mode; it is just annoying to have the server exit just when you 2209 * are about to discover the bug. 2210 */ 2211 ssh_signal(SIGALRM, grace_alarm_handler); 2212 if (!debug_flag) 2213 alarm(options.login_grace_time); 2214 2215 if ((r = kex_exchange_identification(ssh, -1, 2216 options.version_addendum)) != 0) 2217 sshpkt_fatal(ssh, r, "banner exchange"); 2218 2219 ssh_packet_set_nonblocking(ssh); 2220 2221 /* allocate authentication context */ 2222 authctxt = xcalloc(1, sizeof(*authctxt)); 2223 ssh->authctxt = authctxt; 2224 2225 authctxt->loginmsg = loginmsg; 2226 2227 /* XXX global for cleanup, access from other modules */ 2228 the_authctxt = authctxt; 2229 2230 /* Set default key authentication options */ 2231 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2232 fatal("allocation failed"); 2233 2234 /* prepare buffer to collect messages to display to user after login */ 2235 if ((loginmsg = sshbuf_new()) == NULL) 2236 fatal_f("sshbuf_new failed"); 2237 auth_debug_reset(); 2238 2239 if (use_privsep) { 2240 if (privsep_preauth(ssh) == 1) 2241 goto authenticated; 2242 } else if (have_agent) { 2243 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2244 error_r(r, "Unable to get agent socket"); 2245 have_agent = 0; 2246 } 2247 } 2248 2249 /* perform the key exchange */ 2250 /* authenticate user and start session */ 2251 do_ssh2_kex(ssh); 2252 do_authentication2(ssh); 2253 2254 /* 2255 * If we use privilege separation, the unprivileged child transfers 2256 * the current keystate and exits 2257 */ 2258 if (use_privsep) { 2259 mm_send_keystate(ssh, pmonitor); 2260 ssh_packet_clear_keys(ssh); 2261 exit(0); 2262 } 2263 2264 authenticated: 2265 /* 2266 * Cancel the alarm we set to limit the time taken for 2267 * authentication. 2268 */ 2269 alarm(0); 2270 ssh_signal(SIGALRM, SIG_DFL); 2271 authctxt->authenticated = 1; 2272 if (startup_pipe != -1) { 2273 close(startup_pipe); 2274 startup_pipe = -1; 2275 } 2276 2277 #ifdef SSH_AUDIT_EVENTS 2278 audit_event(ssh, SSH_AUTH_SUCCESS); 2279 #endif 2280 2281 #ifdef GSSAPI 2282 if (options.gss_authentication) { 2283 temporarily_use_uid(authctxt->pw); 2284 ssh_gssapi_storecreds(); 2285 restore_uid(); 2286 } 2287 #endif 2288 #ifdef USE_PAM 2289 if (options.use_pam) { 2290 do_pam_setcred(1); 2291 do_pam_session(ssh); 2292 } 2293 #endif 2294 2295 /* 2296 * In privilege separation, we fork another child and prepare 2297 * file descriptor passing. 2298 */ 2299 if (use_privsep) { 2300 privsep_postauth(ssh, authctxt); 2301 /* the monitor process [priv] will not return */ 2302 } 2303 2304 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2305 options.client_alive_count_max); 2306 2307 /* Try to send all our hostkeys to the client */ 2308 notify_hostkeys(ssh); 2309 2310 /* Start session. */ 2311 do_authenticated(ssh, authctxt); 2312 2313 /* The connection has been terminated. */ 2314 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2315 verbose("Transferred: sent %llu, received %llu bytes", 2316 (unsigned long long)obytes, (unsigned long long)ibytes); 2317 2318 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2319 2320 #ifdef USE_PAM 2321 if (options.use_pam) 2322 finish_pam(); 2323 #endif /* USE_PAM */ 2324 2325 #ifdef SSH_AUDIT_EVENTS 2326 PRIVSEP(audit_event(ssh, SSH_CONNECTION_CLOSE)); 2327 #endif 2328 2329 ssh_packet_close(ssh); 2330 2331 if (use_privsep) 2332 mm_terminate(); 2333 2334 exit(0); 2335 } 2336 2337 int 2338 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2339 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2340 const u_char *data, size_t dlen, const char *alg) 2341 { 2342 int r; 2343 2344 if (use_privsep) { 2345 if (privkey) { 2346 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2347 data, dlen, alg, options.sk_provider, NULL, 2348 ssh->compat) < 0) 2349 fatal_f("privkey sign failed"); 2350 } else { 2351 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2352 data, dlen, alg, options.sk_provider, NULL, 2353 ssh->compat) < 0) 2354 fatal_f("pubkey sign failed"); 2355 } 2356 } else { 2357 if (privkey) { 2358 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2359 alg, options.sk_provider, NULL, ssh->compat) < 0) 2360 fatal_f("privkey sign failed"); 2361 } else { 2362 if ((r = ssh_agent_sign(auth_sock, pubkey, 2363 signature, slenp, data, dlen, alg, 2364 ssh->compat)) != 0) { 2365 fatal_fr(r, "agent sign failed"); 2366 } 2367 } 2368 } 2369 return 0; 2370 } 2371 2372 /* SSH2 key exchange */ 2373 static void 2374 do_ssh2_kex(struct ssh *ssh) 2375 { 2376 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2377 struct kex *kex; 2378 char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL; 2379 int r; 2380 2381 myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh, 2382 options.kex_algorithms); 2383 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2384 myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc = 2385 compat_cipher_proposal(ssh, options.ciphers); 2386 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2387 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2388 2389 if (options.compression == COMP_NONE) { 2390 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2391 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2392 } 2393 2394 if (options.rekey_limit || options.rekey_interval) 2395 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2396 options.rekey_interval); 2397 2398 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 2399 compat_pkalg_proposal(ssh, list_hostkey_types()); 2400 2401 /* start key exchange */ 2402 if ((r = kex_setup(ssh, myproposal)) != 0) 2403 fatal_r(r, "kex_setup"); 2404 kex = ssh->kex; 2405 #ifdef WITH_OPENSSL 2406 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2407 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2408 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2409 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2410 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2411 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2412 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2413 # ifdef OPENSSL_HAS_ECC 2414 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2415 # endif 2416 #endif 2417 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2418 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 2419 kex->load_host_public_key=&get_hostkey_public_by_type; 2420 kex->load_host_private_key=&get_hostkey_private_by_type; 2421 kex->host_key_index=&get_hostkey_index; 2422 kex->sign = sshd_hostkey_sign; 2423 2424 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2425 2426 #ifdef DEBUG_KEXDH 2427 /* send 1st encrypted/maced/compressed message */ 2428 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2429 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2430 (r = sshpkt_send(ssh)) != 0 || 2431 (r = ssh_packet_write_wait(ssh)) != 0) 2432 fatal_fr(r, "send test"); 2433 #endif 2434 free(prop_kex); 2435 free(prop_enc); 2436 free(prop_hostkey); 2437 debug("KEX done"); 2438 } 2439 2440 /* server specific fatal cleanup */ 2441 void 2442 cleanup_exit(int i) 2443 { 2444 if (the_active_state != NULL && the_authctxt != NULL) { 2445 do_cleanup(the_active_state, the_authctxt); 2446 if (use_privsep && privsep_is_preauth && 2447 pmonitor != NULL && pmonitor->m_pid > 1) { 2448 debug("Killing privsep child %d", pmonitor->m_pid); 2449 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2450 errno != ESRCH) { 2451 error_f("kill(%d): %s", pmonitor->m_pid, 2452 strerror(errno)); 2453 } 2454 } 2455 } 2456 #ifdef SSH_AUDIT_EVENTS 2457 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2458 if (the_active_state != NULL && (!use_privsep || mm_is_monitor())) 2459 audit_event(the_active_state, SSH_CONNECTION_ABANDON); 2460 #endif 2461 _exit(i); 2462 } 2463