1 /* $NetBSD: sshd.c,v 1.54 2024/09/24 21:32:19 christos Exp $ */ 2 /* $OpenBSD: sshd.c,v 1.612 2024/09/15 01:11:26 djm Exp $ */ 3 4 /* 5 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 6 * Copyright (c) 2002 Niels Provos. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include "includes.h" 30 __RCSID("$NetBSD: sshd.c,v 1.54 2024/09/24 21:32:19 christos Exp $"); 31 #include <sys/types.h> 32 #include <sys/param.h> 33 #include <sys/ioctl.h> 34 #include <sys/wait.h> 35 #include <sys/tree.h> 36 #include <sys/stat.h> 37 #include <sys/socket.h> 38 #include <sys/time.h> 39 #include <sys/queue.h> 40 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <netdb.h> 44 #include <paths.h> 45 #include <poll.h> 46 #include <pwd.h> 47 #include <signal.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <stdarg.h> 52 #include <unistd.h> 53 #include <limits.h> 54 55 #ifdef WITH_OPENSSL 56 #include <openssl/bn.h> 57 #include <openssl/evp.h> 58 #endif 59 60 #include "xmalloc.h" 61 #include "ssh.h" 62 #include "sshpty.h" 63 #include "log.h" 64 #include "sshbuf.h" 65 #include "misc.h" 66 #include "servconf.h" 67 #include "compat.h" 68 #include "digest.h" 69 #include "sshkey.h" 70 #include "authfile.h" 71 #include "pathnames.h" 72 #include "canohost.h" 73 #include "hostfile.h" 74 #include "auth.h" 75 #include "authfd.h" 76 #include "misc.h" 77 #include "msg.h" 78 #include "version.h" 79 #include "ssherr.h" 80 #include "sk-api.h" 81 #include "addr.h" 82 #include "srclimit.h" 83 84 #ifdef LIBWRAP 85 #include <tcpd.h> 86 #include <syslog.h> 87 int allow_severity = LOG_INFO; 88 int deny_severity = LOG_WARNING; 89 #endif /* LIBWRAP */ 90 91 #ifdef WITH_LDAP_PUBKEY 92 #include "ldapauth.h" 93 #endif 94 95 #ifndef HOST_NAME_MAX 96 #define HOST_NAME_MAX MAXHOSTNAMELEN 97 #endif 98 99 /* Re-exec fds */ 100 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 101 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 102 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 103 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 104 105 extern char *__progname; 106 107 /* Server configuration options. */ 108 ServerOptions options; 109 110 /* 111 * Debug mode flag. This can be set on the command line. If debug 112 * mode is enabled, extra debugging output will be sent to the system 113 * log, the daemon will not go to background, and will exit after processing 114 * the first connection. 115 */ 116 int debug_flag = 0; 117 118 /* Saved arguments to main(). */ 119 static char **saved_argv; 120 121 /* 122 * The sockets that the server is listening; this is used in the SIGHUP 123 * signal handler. 124 */ 125 #define MAX_LISTEN_SOCKS 16 126 static int listen_socks[MAX_LISTEN_SOCKS]; 127 static int num_listen_socks = 0; 128 129 /* 130 * Any really sensitive data in the application is contained in this 131 * structure. The idea is that this structure could be locked into memory so 132 * that the pages do not get written into swap. However, there are some 133 * problems. The private key contains BIGNUMs, and we do not (in principle) 134 * have access to the internals of them, and locking just the structure is 135 * not very useful. Currently, memory locking is not implemented. 136 */ 137 struct { 138 struct sshkey **host_keys; /* all private host keys */ 139 struct sshkey **host_pubkeys; /* all public host keys */ 140 struct sshkey **host_certificates; /* all public host certificates */ 141 int have_ssh2_key; 142 } sensitive_data; 143 144 /* This is set to true when a signal is received. */ 145 static volatile sig_atomic_t received_siginfo = 0; 146 static volatile sig_atomic_t received_sigchld = 0; 147 static volatile sig_atomic_t received_sighup = 0; 148 static volatile sig_atomic_t received_sigterm = 0; 149 150 /* record remote hostname or ip */ 151 u_int utmp_len = HOST_NAME_MAX+1; 152 153 /* 154 * The early_child/children array below is used for tracking children of the 155 * listening sshd process early in their lifespans, before they have 156 * completed authentication. This tracking is needed for four things: 157 * 158 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 159 * connections. 160 * 2) Avoiding a race condition for SIGHUP processing, where child processes 161 * may have listen_socks open that could collide with main listener process 162 * after it restarts. 163 * 3) Ensuring that rexec'd sshd processes have received their initial state 164 * from the parent listen process before handling SIGHUP. 165 * 4) Tracking and logging unsuccessful exits from the preauth sshd monitor, 166 * including and especially those for LoginGraceTime timeouts. 167 * 168 * Child processes signal that they have completed closure of the listen_socks 169 * and (if applicable) received their rexec state by sending a char over their 170 * sock. 171 * 172 * Child processes signal that authentication has completed by sending a 173 * second char over the socket before closing it, otherwise the listener will 174 * continue tracking the child (and using up a MaxStartups slot) until the 175 * preauth subprocess exits, whereupon the listener will log its exit status. 176 * preauth processes will exit with a status of EXIT_LOGIN_GRACE to indicate 177 * they did not authenticate before the LoginGraceTime alarm fired. 178 */ 179 struct early_child { 180 int pipefd; 181 int early; /* Indicates child closed listener */ 182 char *id; /* human readable connection identifier */ 183 pid_t pid; 184 struct xaddr addr; 185 int have_addr; 186 int status, have_status; 187 }; 188 static struct early_child *children; 189 static int children_active; 190 static int startup_pipe = -1; /* in child */ 191 192 /* sshd_config buffer */ 193 struct sshbuf *cfg; 194 195 /* Included files from the configuration file */ 196 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 197 198 /* message to be displayed after login */ 199 struct sshbuf *loginmsg; 200 201 static char *listener_proctitle; 202 203 /* 204 * Close all listening sockets 205 */ 206 static void 207 close_listen_socks(void) 208 { 209 int i; 210 211 for (i = 0; i < num_listen_socks; i++) 212 close(listen_socks[i]); 213 num_listen_socks = 0; 214 } 215 216 /* Allocate and initialise the children array */ 217 static void 218 child_alloc(void) 219 { 220 int i; 221 222 children = xcalloc(options.max_startups, sizeof(*children)); 223 for (i = 0; i < options.max_startups; i++) { 224 children[i].pipefd = -1; 225 children[i].pid = -1; 226 } 227 } 228 229 /* Register a new connection in the children array; child pid comes later */ 230 static struct early_child * 231 child_register(int pipefd, int sockfd) 232 { 233 int i, lport, rport; 234 char *laddr = NULL, *raddr = NULL; 235 struct early_child *child = NULL; 236 struct sockaddr_storage addr; 237 socklen_t addrlen = sizeof(addr); 238 struct sockaddr *sa = (struct sockaddr *)&addr; 239 240 for (i = 0; i < options.max_startups; i++) { 241 if (children[i].pipefd != -1 || children[i].pid > 0) 242 continue; 243 child = &(children[i]); 244 break; 245 } 246 if (child == NULL) { 247 fatal_f("error: accepted connection when all %d child " 248 " slots full", options.max_startups); 249 } 250 child->pipefd = pipefd; 251 child->early = 1; 252 /* record peer address, if available */ 253 if (getpeername(sockfd, sa, &addrlen) == 0 && 254 addr_sa_to_xaddr(sa, addrlen, &child->addr) == 0) 255 child->have_addr = 1; 256 /* format peer address string for logs */ 257 if ((lport = get_local_port(sockfd)) == 0 || 258 (rport = get_peer_port(sockfd)) == 0) { 259 /* Not a TCP socket */ 260 raddr = get_peer_ipaddr(sockfd); 261 xasprintf(&child->id, "connection from %s", raddr); 262 } else { 263 laddr = get_local_ipaddr(sockfd); 264 raddr = get_peer_ipaddr(sockfd); 265 xasprintf(&child->id, "connection from %s to %s", raddr, laddr); 266 } 267 free(laddr); 268 free(raddr); 269 if (++children_active > options.max_startups) 270 fatal_f("internal error: more children than max_startups"); 271 272 return child; 273 } 274 275 /* 276 * Finally free a child entry. Don't call this directly. 277 */ 278 static void 279 child_finish(struct early_child *child) 280 { 281 if (children_active == 0) 282 fatal_f("internal error: children_active underflow"); 283 if (child->pipefd != -1) 284 close(child->pipefd); 285 free(child->id); 286 memset(child, '\0', sizeof(*child)); 287 child->pipefd = -1; 288 child->pid = -1; 289 children_active--; 290 } 291 292 /* 293 * Close a child's pipe. This will not stop tracking the child immediately 294 * (it will still be tracked for waitpid()) unless force_final is set, or 295 * child has already exited. 296 */ 297 static void 298 child_close(struct early_child *child, int force_final, int quiet) 299 { 300 if (!quiet) 301 debug_f("enter%s", force_final ? " (forcing)" : ""); 302 if (child->pipefd != -1) { 303 close(child->pipefd); 304 child->pipefd = -1; 305 } 306 if (child->pid == -1 || force_final) 307 child_finish(child); 308 } 309 310 /* Record a child exit. Safe to call from signal handlers */ 311 static void 312 child_exit(pid_t pid, int status) 313 { 314 int i; 315 316 if (children == NULL || pid <= 0) 317 return; 318 for (i = 0; i < options.max_startups; i++) { 319 if (children[i].pid == pid) { 320 children[i].have_status = 1; 321 children[i].status = status; 322 break; 323 } 324 } 325 } 326 327 /* 328 * Reap a child entry that has exited, as previously flagged 329 * using child_exit(). 330 * Handles logging of exit condition and will finalise the child if its pipe 331 * had already been closed. 332 */ 333 static void 334 child_reap(struct early_child *child) 335 { 336 LogLevel level = SYSLOG_LEVEL_DEBUG1; 337 int was_crash, penalty_type = SRCLIMIT_PENALTY_NONE; 338 339 /* Log exit information */ 340 if (WIFSIGNALED(child->status)) { 341 /* 342 * Increase logging for signals potentially associated 343 * with serious conditions. 344 */ 345 if ((was_crash = signal_is_crash(WTERMSIG(child->status)))) 346 level = SYSLOG_LEVEL_ERROR; 347 do_log2(level, "session process %ld for %s killed by " 348 "signal %d%s", (long)child->pid, child->id, 349 WTERMSIG(child->status), child->early ? " (early)" : ""); 350 if (was_crash) 351 penalty_type = SRCLIMIT_PENALTY_CRASH; 352 } else if (!WIFEXITED(child->status)) { 353 penalty_type = SRCLIMIT_PENALTY_CRASH; 354 error("session process %ld for %s terminated abnormally, " 355 "status=0x%x%s", (long)child->pid, child->id, child->status, 356 child->early ? " (early)" : ""); 357 } else { 358 /* Normal exit. We care about the status */ 359 switch (WEXITSTATUS(child->status)) { 360 case 0: 361 debug3_f("preauth child %ld for %s completed " 362 "normally %s", (long)child->pid, child->id, 363 child->early ? " (early)" : ""); 364 break; 365 case EXIT_LOGIN_GRACE: 366 penalty_type = SRCLIMIT_PENALTY_GRACE_EXCEEDED; 367 logit("Timeout before authentication for %s, " 368 "pid = %ld%s", child->id, (long)child->pid, 369 child->early ? " (early)" : ""); 370 break; 371 case EXIT_CHILD_CRASH: 372 penalty_type = SRCLIMIT_PENALTY_CRASH; 373 logit("Session process %ld unpriv child crash for %s%s", 374 (long)child->pid, child->id, 375 child->early ? " (early)" : ""); 376 break; 377 case EXIT_AUTH_ATTEMPTED: 378 penalty_type = SRCLIMIT_PENALTY_AUTHFAIL; 379 debug_f("preauth child %ld for %s exited " 380 "after unsuccessful auth attempt %s", 381 (long)child->pid, child->id, 382 child->early ? " (early)" : ""); 383 break; 384 case EXIT_CONFIG_REFUSED: 385 penalty_type = SRCLIMIT_PENALTY_REFUSECONNECTION; 386 debug_f("preauth child %ld for %s prohibited by" 387 "RefuseConnection %s", 388 (long)child->pid, child->id, 389 child->early ? " (early)" : ""); 390 break; 391 default: 392 penalty_type = SRCLIMIT_PENALTY_NOAUTH; 393 debug_f("preauth child %ld for %s exited " 394 "with status %d%s", (long)child->pid, child->id, 395 WEXITSTATUS(child->status), 396 child->early ? " (early)" : ""); 397 break; 398 } 399 } 400 401 if (child->have_addr) 402 srclimit_penalise(&child->addr, penalty_type); 403 404 child->pid = -1; 405 child->have_status = 0; 406 if (child->pipefd == -1) 407 child_finish(child); 408 } 409 410 /* Reap all children that have exited; called after SIGCHLD */ 411 static void 412 child_reap_all_exited(void) 413 { 414 int i; 415 pid_t pid; 416 int status; 417 418 if (children == NULL) 419 return; 420 421 for (;;) { 422 if ((pid = waitpid(-1, &status, WNOHANG)) == 0) 423 break; 424 else if (pid == -1) { 425 if (errno == EINTR || errno == EAGAIN) 426 continue; 427 if (errno != ECHILD) 428 error_f("waitpid: %s", strerror(errno)); 429 break; 430 } 431 child_exit(pid, status); 432 } 433 434 for (i = 0; i < options.max_startups; i++) { 435 if (!children[i].have_status) 436 continue; 437 child_reap(&(children[i])); 438 } 439 } 440 441 static void 442 close_startup_pipes(void) 443 { 444 int i; 445 446 if (children == NULL) 447 return; 448 for (i = 0; i < options.max_startups; i++) { 449 if (children[i].pipefd != -1) 450 child_close(&(children[i]), 1, 1); 451 } 452 } 453 454 /* Called after SIGINFO */ 455 static void 456 show_info(void) 457 { 458 int i; 459 460 /* XXX print listening sockets here too */ 461 if (children == NULL) 462 return; 463 logit("%d active startups", children_active); 464 for (i = 0; i < options.max_startups; i++) { 465 if (children[i].pipefd == -1 && children[i].pid <= 0) 466 continue; 467 logit("child %d: fd=%d pid=%ld %s%s", i, children[i].pipefd, 468 (long)children[i].pid, children[i].id, 469 children[i].early ? " (early)" : ""); 470 } 471 srclimit_penalty_info(); 472 } 473 474 /* 475 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 476 * the effect is to reread the configuration file (and to regenerate 477 * the server key). 478 */ 479 480 static void 481 sighup_handler(int sig) 482 { 483 received_sighup = 1; 484 } 485 486 /* 487 * Called from the main program after receiving SIGHUP. 488 * Restarts the server. 489 */ 490 __dead 491 static void 492 sighup_restart(void) 493 { 494 logit("Received SIGHUP; restarting."); 495 if (options.pid_file != NULL) 496 unlink(options.pid_file); 497 close_listen_socks(); 498 close_startup_pipes(); 499 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 500 execv(saved_argv[0], saved_argv); 501 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 502 strerror(errno)); 503 exit(1); 504 } 505 506 /* 507 * Generic signal handler for terminating signals in the master daemon. 508 */ 509 static void 510 sigterm_handler(int sig) 511 { 512 received_sigterm = sig; 513 } 514 515 static void 516 siginfo_handler(int sig) 517 { 518 received_siginfo = 1; 519 } 520 521 static void 522 main_sigchld_handler(int sig) 523 { 524 received_sigchld = 1; 525 } 526 527 /* 528 * returns 1 if connection should be dropped, 0 otherwise. 529 * dropping starts at connection #max_startups_begin with a probability 530 * of (max_startups_rate/100). the probability increases linearly until 531 * all connections are dropped for startups > max_startups 532 */ 533 static int 534 should_drop_connection(int startups) 535 { 536 int p, r; 537 538 if (startups < options.max_startups_begin) 539 return 0; 540 if (startups >= options.max_startups) 541 return 1; 542 if (options.max_startups_rate == 100) 543 return 1; 544 545 p = 100 - options.max_startups_rate; 546 p *= startups - options.max_startups_begin; 547 p /= options.max_startups - options.max_startups_begin; 548 p += options.max_startups_rate; 549 r = arc4random_uniform(100); 550 551 debug_f("p %d, r %d", p, r); 552 return (r < p) ? 1 : 0; 553 } 554 555 /* 556 * Check whether connection should be accepted by MaxStartups or for penalty. 557 * Returns 0 if the connection is accepted. If the connection is refused, 558 * returns 1 and attempts to send notification to client. 559 * Logs when the MaxStartups condition is entered or exited, and periodically 560 * while in that state. 561 */ 562 static int 563 drop_connection(int sock, int startups, int notify_pipe) 564 { 565 char *laddr, *raddr; 566 const char *reason = NULL, msg[] = "Not allowed at this time\r\n"; 567 static time_t last_drop, first_drop; 568 static u_int ndropped; 569 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 570 time_t now; 571 572 if (!srclimit_penalty_check_allow(sock, &reason)) { 573 drop_level = SYSLOG_LEVEL_INFO; 574 goto handle; 575 } 576 577 now = monotime(); 578 if (!should_drop_connection(startups) && 579 srclimit_check_allow(sock, notify_pipe) == 1) { 580 if (last_drop != 0 && 581 startups < options.max_startups_begin - 1) { 582 /* XXX maybe need better hysteresis here */ 583 logit("exited MaxStartups throttling after %s, " 584 "%u connections dropped", 585 fmt_timeframe(now - first_drop), ndropped); 586 last_drop = 0; 587 } 588 return 0; 589 } 590 591 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 592 if (last_drop == 0) { 593 error("beginning MaxStartups throttling"); 594 drop_level = SYSLOG_LEVEL_INFO; 595 first_drop = now; 596 ndropped = 0; 597 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 598 /* Periodic logs */ 599 error("in MaxStartups throttling for %s, " 600 "%u connections dropped", 601 fmt_timeframe(now - first_drop), ndropped + 1); 602 drop_level = SYSLOG_LEVEL_INFO; 603 } 604 last_drop = now; 605 ndropped++; 606 reason = "past Maxstartups"; 607 608 handle: 609 laddr = get_local_ipaddr(sock); 610 raddr = get_peer_ipaddr(sock); 611 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d %s", 612 startups, 613 raddr, get_peer_port(sock), 614 laddr, get_local_port(sock), 615 reason); 616 free(laddr); 617 free(raddr); 618 /* best-effort notification to client */ 619 (void)write(sock, msg, sizeof(msg) - 1); 620 return 1; 621 } 622 623 __dead static void 624 usage(void) 625 { 626 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION); 627 fprintf(stderr, 628 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n" 629 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 630 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 631 ); 632 exit(1); 633 } 634 635 static struct sshbuf * 636 pack_hostkeys(void) 637 { 638 struct sshbuf *keybuf = NULL, *hostkeys = NULL; 639 int r; 640 u_int i; 641 642 if ((keybuf = sshbuf_new()) == NULL || 643 (hostkeys = sshbuf_new()) == NULL) 644 fatal_f("sshbuf_new failed"); 645 646 /* pack hostkeys into a string. Empty key slots get empty strings */ 647 for (i = 0; i < options.num_host_key_files; i++) { 648 /* private key */ 649 sshbuf_reset(keybuf); 650 if (sensitive_data.host_keys[i] != NULL && 651 (r = sshkey_private_serialize(sensitive_data.host_keys[i], 652 keybuf)) != 0) 653 fatal_fr(r, "serialize hostkey private"); 654 if ((r = sshbuf_put_stringb(hostkeys, keybuf)) != 0) 655 fatal_fr(r, "compose hostkey private"); 656 /* public key */ 657 if (sensitive_data.host_pubkeys[i] != NULL) { 658 if ((r = sshkey_puts(sensitive_data.host_pubkeys[i], 659 hostkeys)) != 0) 660 fatal_fr(r, "compose hostkey public"); 661 } else { 662 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 663 fatal_fr(r, "compose hostkey empty public"); 664 } 665 /* cert */ 666 if (sensitive_data.host_certificates[i] != NULL) { 667 if ((r = sshkey_puts( 668 sensitive_data.host_certificates[i], 669 hostkeys)) != 0) 670 fatal_fr(r, "compose host cert"); 671 } else { 672 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 673 fatal_fr(r, "compose host cert empty"); 674 } 675 } 676 677 sshbuf_free(keybuf); 678 return hostkeys; 679 } 680 681 static void 682 send_rexec_state(int fd, struct sshbuf *conf) 683 { 684 struct sshbuf *m = NULL, *inc = NULL, *hostkeys = NULL; 685 struct include_item *item = NULL; 686 int r, sz; 687 688 debug3_f("entering fd = %d config len %zu", fd, 689 sshbuf_len(conf)); 690 691 if ((m = sshbuf_new()) == NULL || 692 (inc = sshbuf_new()) == NULL) 693 fatal_f("sshbuf_new failed"); 694 695 /* pack includes into a string */ 696 TAILQ_FOREACH(item, &includes, entry) { 697 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 698 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 699 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 700 fatal_fr(r, "compose includes"); 701 } 702 703 hostkeys = pack_hostkeys(); 704 705 /* 706 * Protocol from reexec master to child: 707 * string configuration 708 * uint64 timing_secret 709 * string host_keys[] { 710 * string private_key 711 * string public_key 712 * string certificate 713 * } 714 * string included_files[] { 715 * string selector 716 * string filename 717 * string contents 718 * } 719 */ 720 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 721 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 || 722 (r = sshbuf_put_stringb(m, hostkeys)) != 0 || 723 (r = sshbuf_put_stringb(m, inc)) != 0) 724 fatal_fr(r, "compose config"); 725 726 /* We need to fit the entire message inside the socket send buffer */ 727 sz = ROUNDUP(sshbuf_len(m) + 5, 16*1024); 728 if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sz, sizeof sz) == -1) 729 fatal_f("setsockopt SO_SNDBUF: %s", strerror(errno)); 730 731 if (ssh_msg_send(fd, 0, m) == -1) 732 error_f("ssh_msg_send failed"); 733 734 sshbuf_free(m); 735 sshbuf_free(inc); 736 sshbuf_free(hostkeys); 737 738 debug3_f("done"); 739 } 740 741 /* 742 * Listen for TCP connections 743 */ 744 static void 745 listen_on_addrs(struct listenaddr *la) 746 { 747 int ret, listen_sock; 748 struct addrinfo *ai; 749 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 750 int socksize; 751 socklen_t socksizelen = sizeof(int); 752 753 for (ai = la->addrs; ai; ai = ai->ai_next) { 754 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 755 continue; 756 if (num_listen_socks >= MAX_LISTEN_SOCKS) 757 fatal("Too many listen sockets. " 758 "Enlarge MAX_LISTEN_SOCKS"); 759 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 760 ntop, sizeof(ntop), strport, sizeof(strport), 761 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 762 error("getnameinfo failed: %.100s", 763 ssh_gai_strerror(ret)); 764 continue; 765 } 766 /* Create socket for listening. */ 767 listen_sock = socket(ai->ai_family, ai->ai_socktype, 768 ai->ai_protocol); 769 if (listen_sock == -1) { 770 /* kernel may not support ipv6 */ 771 verbose("socket: %.100s", strerror(errno)); 772 continue; 773 } 774 if (set_nonblock(listen_sock) == -1) { 775 close(listen_sock); 776 continue; 777 } 778 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 779 verbose("socket: CLOEXEC: %s", strerror(errno)); 780 close(listen_sock); 781 continue; 782 } 783 /* Socket options */ 784 set_reuseaddr(listen_sock); 785 if (la->rdomain != NULL && 786 set_rdomain(listen_sock, la->rdomain) == -1) { 787 close(listen_sock); 788 continue; 789 } 790 791 debug("Bind to port %s on %s.", strport, ntop); 792 793 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 794 &socksize, &socksizelen); 795 debug("Server TCP RWIN socket size: %d", socksize); 796 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 797 798 /* Bind the socket to the desired port. */ 799 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 800 error("Bind to port %s on %s failed: %.200s.", 801 strport, ntop, strerror(errno)); 802 close(listen_sock); 803 continue; 804 } 805 listen_socks[num_listen_socks] = listen_sock; 806 num_listen_socks++; 807 808 /* Start listening on the port. */ 809 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 810 fatal("listen on [%s]:%s: %.100s", 811 ntop, strport, strerror(errno)); 812 logit("Server listening on %s port %s%s%s.", 813 ntop, strport, 814 la->rdomain == NULL ? "" : " rdomain ", 815 la->rdomain == NULL ? "" : la->rdomain); 816 } 817 } 818 819 static void 820 server_listen(void) 821 { 822 u_int i; 823 824 /* Initialise per-source limit tracking. */ 825 srclimit_init(options.max_startups, 826 options.per_source_max_startups, 827 options.per_source_masklen_ipv4, 828 options.per_source_masklen_ipv6, 829 &options.per_source_penalty, 830 options.per_source_penalty_exempt); 831 832 for (i = 0; i < options.num_listen_addrs; i++) { 833 listen_on_addrs(&options.listen_addrs[i]); 834 freeaddrinfo(options.listen_addrs[i].addrs); 835 free(options.listen_addrs[i].rdomain); 836 memset(&options.listen_addrs[i], 0, 837 sizeof(options.listen_addrs[i])); 838 } 839 free(options.listen_addrs); 840 options.listen_addrs = NULL; 841 options.num_listen_addrs = 0; 842 843 if (!num_listen_socks) 844 fatal("Cannot bind any address."); 845 } 846 847 /* 848 * The main TCP accept loop. Note that, for the non-debug case, returns 849 * from this function are in a forked subprocess. 850 */ 851 static void 852 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s, 853 int log_stderr) 854 { 855 struct pollfd *pfd = NULL; 856 int i, ret, npfd; 857 int oactive = -1, listening = 0, lameduck = 0; 858 int startup_p[2] = { -1 , -1 }, *startup_pollfd; 859 char c = 0; 860 struct sockaddr_storage from; 861 struct early_child *child; 862 socklen_t fromlen; 863 sigset_t nsigset, osigset; 864 865 /* setup fd set for accept */ 866 /* pipes connected to unauthenticated child sshd processes */ 867 child_alloc(); 868 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 869 870 /* 871 * Prepare signal mask that we use to block signals that might set 872 * received_sigterm/hup/chld/info, so that we are guaranteed 873 * to immediately wake up the ppoll if a signal is received after 874 * the flag is checked. 875 */ 876 sigemptyset(&nsigset); 877 sigaddset(&nsigset, SIGHUP); 878 sigaddset(&nsigset, SIGCHLD); 879 sigaddset(&nsigset, SIGINFO); 880 sigaddset(&nsigset, SIGTERM); 881 sigaddset(&nsigset, SIGQUIT); 882 883 /* sized for worst-case */ 884 pfd = xcalloc(num_listen_socks + options.max_startups, 885 sizeof(struct pollfd)); 886 887 /* 888 * Stay listening for connections until the system crashes or 889 * the daemon is killed with a signal. 890 */ 891 for (;;) { 892 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 893 if (received_sigterm) { 894 logit("Received signal %d; terminating.", 895 (int) received_sigterm); 896 close_listen_socks(); 897 if (options.pid_file != NULL) 898 unlink(options.pid_file); 899 exit(received_sigterm == SIGTERM ? 0 : 255); 900 } 901 if (received_sigchld) { 902 child_reap_all_exited(); 903 received_sigchld = 0; 904 } 905 if (received_siginfo) { 906 show_info(); 907 received_siginfo = 0; 908 } 909 if (oactive != children_active) { 910 setproctitle("%s [listener] %d of %d-%d startups", 911 listener_proctitle, children_active, 912 options.max_startups_begin, options.max_startups); 913 oactive = children_active; 914 } 915 if (received_sighup) { 916 if (!lameduck) { 917 debug("Received SIGHUP; waiting for children"); 918 close_listen_socks(); 919 lameduck = 1; 920 } 921 if (listening <= 0) { 922 sigprocmask(SIG_SETMASK, &osigset, NULL); 923 sighup_restart(); 924 } 925 } 926 927 for (i = 0; i < num_listen_socks; i++) { 928 pfd[i].fd = listen_socks[i]; 929 pfd[i].events = POLLIN; 930 } 931 npfd = num_listen_socks; 932 for (i = 0; i < options.max_startups; i++) { 933 startup_pollfd[i] = -1; 934 if (children[i].pipefd != -1) { 935 pfd[npfd].fd = children[i].pipefd; 936 pfd[npfd].events = POLLIN; 937 startup_pollfd[i] = npfd++; 938 } 939 } 940 941 /* Wait until a connection arrives or a child exits. */ 942 ret = ppoll(pfd, npfd, NULL, &osigset); 943 if (ret == -1 && errno != EINTR) { 944 error("ppoll: %.100s", strerror(errno)); 945 if (errno == EINVAL) 946 cleanup_exit(1); /* can't recover */ 947 } 948 sigprocmask(SIG_SETMASK, &osigset, NULL); 949 if (ret == -1) 950 continue; 951 952 for (i = 0; i < options.max_startups; i++) { 953 if (children[i].pipefd == -1 || 954 startup_pollfd[i] == -1 || 955 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 956 continue; 957 switch (read(children[i].pipefd, &c, sizeof(c))) { 958 case -1: 959 if (errno == EINTR || errno == EAGAIN) 960 continue; 961 if (errno != EPIPE) { 962 error_f("startup pipe %d (fd=%d): " 963 "read %s", i, children[i].pipefd, 964 strerror(errno)); 965 } 966 /* FALLTHROUGH */ 967 case 0: 968 /* child exited preauth */ 969 if (children[i].early) 970 listening--; 971 srclimit_done(children[i].pipefd); 972 child_close(&(children[i]), 0, 0); 973 break; 974 case 1: 975 if (children[i].early && c == '\0') { 976 /* child has finished preliminaries */ 977 listening--; 978 children[i].early = 0; 979 debug2_f("child %lu for %s received " 980 "config", (long)children[i].pid, 981 children[i].id); 982 } else if (!children[i].early && c == '\001') { 983 /* child has completed auth */ 984 debug2_f("child %lu for %s auth done", 985 (long)children[i].pid, 986 children[i].id); 987 child_close(&(children[i]), 1, 0); 988 } else { 989 error_f("unexpected message 0x%02x " 990 "child %ld for %s in state %d", 991 (int)c, (long)children[i].pid, 992 children[i].id, children[i].early); 993 } 994 break; 995 } 996 } 997 for (i = 0; i < num_listen_socks; i++) { 998 if (!(pfd[i].revents & POLLIN)) 999 continue; 1000 fromlen = sizeof(from); 1001 *newsock = accept(listen_socks[i], 1002 (struct sockaddr *)&from, &fromlen); 1003 if (*newsock == -1) { 1004 if (errno != EINTR && errno != EWOULDBLOCK && 1005 errno != ECONNABORTED) 1006 error("accept: %.100s", 1007 strerror(errno)); 1008 if (errno == EMFILE || errno == ENFILE) 1009 usleep(100 * 1000); 1010 continue; 1011 } 1012 if (unset_nonblock(*newsock) == -1) { 1013 close(*newsock); 1014 continue; 1015 } 1016 if (pipe(startup_p) == -1) { 1017 error_f("pipe(startup_p): %s", strerror(errno)); 1018 close(*newsock); 1019 continue; 1020 } 1021 if (drop_connection(*newsock, 1022 children_active, startup_p[0])) { 1023 close(*newsock); 1024 close(startup_p[0]); 1025 close(startup_p[1]); 1026 continue; 1027 } 1028 1029 if (socketpair(AF_UNIX, 1030 SOCK_STREAM, 0, config_s) == -1) { 1031 error("reexec socketpair: %s", 1032 strerror(errno)); 1033 close(*newsock); 1034 close(startup_p[0]); 1035 close(startup_p[1]); 1036 continue; 1037 } 1038 1039 /* 1040 * Got connection. Fork a child to handle it, unless 1041 * we are in debugging mode. 1042 */ 1043 if (debug_flag) { 1044 /* 1045 * In debugging mode. Close the listening 1046 * socket, and start processing the 1047 * connection without forking. 1048 */ 1049 debug("Server will not fork when running in debugging mode."); 1050 close_listen_socks(); 1051 *sock_in = *newsock; 1052 *sock_out = *newsock; 1053 close(startup_p[0]); 1054 close(startup_p[1]); 1055 startup_pipe = -1; 1056 send_rexec_state(config_s[0], cfg); 1057 close(config_s[0]); 1058 free(pfd); 1059 return; 1060 } 1061 1062 /* 1063 * Normal production daemon. Fork, and have 1064 * the child process the connection. The 1065 * parent continues listening. 1066 */ 1067 listening++; 1068 child = child_register(startup_p[0], *newsock); 1069 if ((child->pid = fork()) == 0) { 1070 /* 1071 * Child. Close the listening and 1072 * max_startup sockets. Start using 1073 * the accepted socket. Reinitialize 1074 * logging (since our pid has changed). 1075 * We return from this function to handle 1076 * the connection. 1077 */ 1078 startup_pipe = startup_p[1]; 1079 close_startup_pipes(); 1080 close_listen_socks(); 1081 *sock_in = *newsock; 1082 *sock_out = *newsock; 1083 log_init(__progname, 1084 options.log_level, 1085 options.log_facility, 1086 log_stderr); 1087 close(config_s[0]); 1088 free(pfd); 1089 return; 1090 } 1091 1092 /* Parent. Stay in the loop. */ 1093 if (child->pid == -1) 1094 error("fork: %.100s", strerror(errno)); 1095 else 1096 debug("Forked child %ld.", (long)child->pid); 1097 1098 close(startup_p[1]); 1099 1100 close(config_s[1]); 1101 send_rexec_state(config_s[0], cfg); 1102 close(config_s[0]); 1103 close(*newsock); 1104 } 1105 } 1106 } 1107 1108 static void 1109 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1110 struct sshkey *key) 1111 { 1112 static struct ssh_digest_ctx *ctx; 1113 u_char *hash; 1114 size_t len; 1115 struct sshbuf *buf; 1116 int r; 1117 1118 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1119 fatal_f("ssh_digest_start"); 1120 if (key == NULL) { /* finalize */ 1121 /* add server config in case we are using agent for host keys */ 1122 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1123 sshbuf_len(server_cfg)) != 0) 1124 fatal_f("ssh_digest_update"); 1125 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1126 hash = xmalloc(len); 1127 if (ssh_digest_final(ctx, hash, len) != 0) 1128 fatal_f("ssh_digest_final"); 1129 options.timing_secret = PEEK_U64(hash); 1130 freezero(hash, len); 1131 ssh_digest_free(ctx); 1132 ctx = NULL; 1133 return; 1134 } 1135 if ((buf = sshbuf_new()) == NULL) 1136 fatal_f("could not allocate buffer"); 1137 if ((r = sshkey_private_serialize(key, buf)) != 0) 1138 fatal_fr(r, "encode %s key", sshkey_ssh_name(key)); 1139 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1140 fatal_f("ssh_digest_update"); 1141 sshbuf_reset(buf); 1142 sshbuf_free(buf); 1143 } 1144 1145 static char * 1146 prepare_proctitle(int ac, char **av) 1147 { 1148 char *ret = NULL; 1149 int i; 1150 1151 for (i = 0; i < ac; i++) 1152 xextendf(&ret, " ", "%s", av[i]); 1153 return ret; 1154 } 1155 1156 __dead static void 1157 print_config(struct connection_info *connection_info) 1158 { 1159 connection_info->test = 1; 1160 parse_server_match_config(&options, &includes, connection_info); 1161 dump_config(&options); 1162 exit(0); 1163 } 1164 1165 /* 1166 * Main program for the daemon. 1167 */ 1168 int 1169 main(int ac, char **av) 1170 { 1171 extern char *optarg; 1172 extern int optind; 1173 int log_stderr = 0, inetd_flag = 0, test_flag = 0, no_daemon_flag = 0; 1174 const char *config_file_name = _PATH_SERVER_CONFIG_FILE; 1175 int r, opt, do_dump_cfg = 0, keytype, already_daemon, have_agent = 0; 1176 int sock_in = -1, sock_out = -1, newsock = -1, rexec_argc = 0; 1177 int devnull, config_s[2] = { -1 , -1 }, have_connection_info = 0; 1178 char *fp, *line, *logfile = NULL, **rexec_argv = NULL; 1179 struct stat sb; 1180 u_int i, j; 1181 mode_t new_umask; 1182 struct sshkey *key; 1183 struct sshkey *pubkey; 1184 struct connection_info connection_info; 1185 sigset_t sigmask; 1186 1187 memset(&connection_info, 0, sizeof(connection_info)); 1188 1189 sigemptyset(&sigmask); 1190 sigprocmask(SIG_SETMASK, &sigmask, NULL); 1191 1192 /* Save argv. */ 1193 saved_argv = av; 1194 rexec_argc = ac; 1195 1196 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1197 sanitise_stdfd(); 1198 1199 /* Initialize configuration options to their default values. */ 1200 initialize_server_options(&options); 1201 1202 /* Parse command-line arguments. */ 1203 while ((opt = getopt(ac, av, 1204 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) { 1205 switch (opt) { 1206 case '4': 1207 options.address_family = AF_INET; 1208 break; 1209 case '6': 1210 options.address_family = AF_INET6; 1211 break; 1212 case 'f': 1213 config_file_name = optarg; 1214 break; 1215 case 'c': 1216 servconf_add_hostcert("[command-line]", 0, 1217 &options, optarg); 1218 break; 1219 case 'd': 1220 if (debug_flag == 0) { 1221 debug_flag = 1; 1222 options.log_level = SYSLOG_LEVEL_DEBUG1; 1223 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1224 options.log_level++; 1225 break; 1226 case 'D': 1227 no_daemon_flag = 1; 1228 break; 1229 case 'G': 1230 do_dump_cfg = 1; 1231 break; 1232 case 'E': 1233 logfile = optarg; 1234 /* FALLTHROUGH */ 1235 case 'e': 1236 log_stderr = 1; 1237 break; 1238 case 'i': 1239 inetd_flag = 1; 1240 break; 1241 case 'r': 1242 logit("-r option is deprecated"); 1243 break; 1244 case 'R': 1245 fatal("-R not supported here"); 1246 break; 1247 case 'Q': 1248 /* ignored */ 1249 break; 1250 case 'q': 1251 options.log_level = SYSLOG_LEVEL_QUIET; 1252 break; 1253 case 'b': 1254 /* protocol 1, ignored */ 1255 break; 1256 case 'p': 1257 options.ports_from_cmdline = 1; 1258 if (options.num_ports >= MAX_PORTS) { 1259 fprintf(stderr, "too many ports.\n"); 1260 exit(1); 1261 } 1262 options.ports[options.num_ports++] = a2port(optarg); 1263 if (options.ports[options.num_ports-1] <= 0) { 1264 fprintf(stderr, "Bad port number.\n"); 1265 exit(1); 1266 } 1267 break; 1268 case 'g': 1269 if ((options.login_grace_time = convtime(optarg)) == -1) { 1270 fprintf(stderr, "Invalid login grace time.\n"); 1271 exit(1); 1272 } 1273 break; 1274 case 'k': 1275 /* protocol 1, ignored */ 1276 break; 1277 case 'h': 1278 servconf_add_hostkey("[command-line]", 0, 1279 &options, optarg, 1); 1280 break; 1281 case 't': 1282 test_flag = 1; 1283 break; 1284 case 'T': 1285 test_flag = 2; 1286 break; 1287 case 'C': 1288 if (parse_server_match_testspec(&connection_info, 1289 optarg) == -1) 1290 exit(1); 1291 have_connection_info = 1; 1292 break; 1293 case 'u': 1294 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1295 if (utmp_len > HOST_NAME_MAX+1) { 1296 fprintf(stderr, "Invalid utmp length.\n"); 1297 exit(1); 1298 } 1299 break; 1300 case 'o': 1301 line = xstrdup(optarg); 1302 if (process_server_config_line(&options, line, 1303 "command-line", 0, NULL, NULL, &includes) != 0) 1304 exit(1); 1305 free(line); 1306 break; 1307 case 'V': 1308 fprintf(stderr, "%s, %s\n", 1309 SSH_VERSION, SSH_OPENSSL_VERSION); 1310 exit(0); 1311 default: 1312 usage(); 1313 break; 1314 } 1315 } 1316 if (!test_flag && !inetd_flag && !do_dump_cfg && !path_absolute(av[0])) 1317 fatal("sshd requires execution with an absolute path"); 1318 1319 closefrom(STDERR_FILENO + 1); 1320 1321 /* Reserve fds we'll need later for reexec things */ 1322 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) 1323 fatal("open %s: %s", _PATH_DEVNULL, strerror(errno)); 1324 while (devnull < REEXEC_MIN_FREE_FD) { 1325 if ((devnull = dup(devnull)) == -1) 1326 fatal("dup %s: %s", _PATH_DEVNULL, strerror(errno)); 1327 } 1328 1329 #ifdef WITH_OPENSSL 1330 OpenSSL_add_all_algorithms(); 1331 #endif 1332 1333 /* If requested, redirect the logs to the specified logfile. */ 1334 if (logfile != NULL) { 1335 char *cp, pid_s[32]; 1336 1337 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid()); 1338 cp = percent_expand(logfile, 1339 "p", pid_s, 1340 "P", "sshd", 1341 (char *)NULL); 1342 log_redirect_stderr_to(cp); 1343 free(cp); 1344 } 1345 1346 /* 1347 * Force logging to stderr until we have loaded the private host 1348 * key (unless started from inetd) 1349 */ 1350 log_init(__progname, 1351 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1352 SYSLOG_LEVEL_INFO : options.log_level, 1353 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1354 SYSLOG_FACILITY_AUTH : options.log_facility, 1355 log_stderr || !inetd_flag || debug_flag); 1356 1357 sensitive_data.have_ssh2_key = 0; 1358 1359 /* 1360 * If we're not doing an extended test do not silently ignore connection 1361 * test params. 1362 */ 1363 if (test_flag < 2 && have_connection_info) 1364 fatal("Config test connection parameter (-C) provided without " 1365 "test mode (-T)"); 1366 1367 /* Fetch our configuration */ 1368 if ((cfg = sshbuf_new()) == NULL) 1369 fatal("sshbuf_new config failed"); 1370 if (strcasecmp(config_file_name, "none") != 0) 1371 load_server_config(config_file_name, cfg); 1372 1373 parse_server_config(&options, config_file_name, cfg, 1374 &includes, NULL, 0); 1375 1376 /* Fill in default values for those options not explicitly set. */ 1377 fill_default_server_options(&options); 1378 1379 /* Check that options are sensible */ 1380 if (options.authorized_keys_command_user == NULL && 1381 (options.authorized_keys_command != NULL && 1382 strcasecmp(options.authorized_keys_command, "none") != 0)) 1383 fatal("AuthorizedKeysCommand set without " 1384 "AuthorizedKeysCommandUser"); 1385 if (options.authorized_principals_command_user == NULL && 1386 (options.authorized_principals_command != NULL && 1387 strcasecmp(options.authorized_principals_command, "none") != 0)) 1388 fatal("AuthorizedPrincipalsCommand set without " 1389 "AuthorizedPrincipalsCommandUser"); 1390 1391 /* 1392 * Check whether there is any path through configured auth methods. 1393 * Unfortunately it is not possible to verify this generally before 1394 * daemonisation in the presence of Match blocks, but this catches 1395 * and warns for trivial misconfigurations that could break login. 1396 */ 1397 if (options.num_auth_methods != 0) { 1398 for (i = 0; i < options.num_auth_methods; i++) { 1399 if (auth2_methods_valid(options.auth_methods[i], 1400 1) == 0) 1401 break; 1402 } 1403 if (i >= options.num_auth_methods) 1404 fatal("AuthenticationMethods cannot be satisfied by " 1405 "enabled authentication methods"); 1406 } 1407 1408 /* Check that there are no remaining arguments. */ 1409 if (optind < ac) { 1410 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1411 exit(1); 1412 } 1413 1414 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1415 1416 if (do_dump_cfg) 1417 print_config(&connection_info); 1418 1419 /* load host keys */ 1420 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1421 sizeof(struct sshkey *)); 1422 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1423 sizeof(struct sshkey *)); 1424 1425 if (options.host_key_agent) { 1426 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1427 setenv(SSH_AUTHSOCKET_ENV_NAME, 1428 options.host_key_agent, 1); 1429 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1430 have_agent = 1; 1431 else 1432 error_r(r, "Could not connect to agent \"%s\"", 1433 options.host_key_agent); 1434 } 1435 1436 for (i = 0; i < options.num_host_key_files; i++) { 1437 int ll = options.host_key_file_userprovided[i] ? 1438 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1439 1440 if (options.host_key_files[i] == NULL) 1441 continue; 1442 if ((r = sshkey_load_private(options.host_key_files[i], "", 1443 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1444 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1445 options.host_key_files[i]); 1446 if (sshkey_is_sk(key) && 1447 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1448 debug("host key %s requires user presence, ignoring", 1449 options.host_key_files[i]); 1450 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1451 } 1452 if (r == 0 && key != NULL && 1453 (r = sshkey_shield_private(key)) != 0) { 1454 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1455 options.host_key_files[i]); 1456 sshkey_free(key); 1457 key = NULL; 1458 } 1459 if ((r = sshkey_load_public(options.host_key_files[i], 1460 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1461 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1462 options.host_key_files[i]); 1463 if (pubkey != NULL && key != NULL) { 1464 if (!sshkey_equal(pubkey, key)) { 1465 error("Public key for %s does not match " 1466 "private key", options.host_key_files[i]); 1467 sshkey_free(pubkey); 1468 pubkey = NULL; 1469 } 1470 } 1471 if (pubkey == NULL && key != NULL) { 1472 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1473 fatal_r(r, "Could not demote key: \"%s\"", 1474 options.host_key_files[i]); 1475 } 1476 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1477 options.required_rsa_size)) != 0) { 1478 error_fr(r, "Host key %s", options.host_key_files[i]); 1479 sshkey_free(pubkey); 1480 sshkey_free(key); 1481 continue; 1482 } 1483 sensitive_data.host_keys[i] = key; 1484 sensitive_data.host_pubkeys[i] = pubkey; 1485 1486 if (key == NULL && pubkey != NULL && have_agent) { 1487 debug("will rely on agent for hostkey %s", 1488 options.host_key_files[i]); 1489 keytype = pubkey->type; 1490 } else if (key != NULL) { 1491 keytype = key->type; 1492 accumulate_host_timing_secret(cfg, key); 1493 } else { 1494 do_log2(ll, "Unable to load host key: %s", 1495 options.host_key_files[i]); 1496 sensitive_data.host_keys[i] = NULL; 1497 sensitive_data.host_pubkeys[i] = NULL; 1498 continue; 1499 } 1500 1501 switch (keytype) { 1502 case KEY_RSA: 1503 case KEY_DSA: 1504 case KEY_ECDSA: 1505 case KEY_ED25519: 1506 case KEY_ECDSA_SK: 1507 case KEY_ED25519_SK: 1508 case KEY_XMSS: 1509 if (have_agent || key != NULL) 1510 sensitive_data.have_ssh2_key = 1; 1511 break; 1512 } 1513 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1514 SSH_FP_DEFAULT)) == NULL) 1515 fatal("sshkey_fingerprint failed"); 1516 debug("%s host key #%d: %s %s", 1517 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1518 free(fp); 1519 } 1520 accumulate_host_timing_secret(cfg, NULL); 1521 if (!sensitive_data.have_ssh2_key) { 1522 logit("sshd: no hostkeys available -- exiting."); 1523 exit(1); 1524 } 1525 1526 /* 1527 * Load certificates. They are stored in an array at identical 1528 * indices to the public keys that they relate to. 1529 */ 1530 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1531 sizeof(struct sshkey *)); 1532 for (i = 0; i < options.num_host_key_files; i++) 1533 sensitive_data.host_certificates[i] = NULL; 1534 1535 for (i = 0; i < options.num_host_cert_files; i++) { 1536 if (options.host_cert_files[i] == NULL) 1537 continue; 1538 if ((r = sshkey_load_public(options.host_cert_files[i], 1539 &key, NULL)) != 0) { 1540 error_r(r, "Could not load host certificate \"%s\"", 1541 options.host_cert_files[i]); 1542 continue; 1543 } 1544 if (!sshkey_is_cert(key)) { 1545 error("Certificate file is not a certificate: %s", 1546 options.host_cert_files[i]); 1547 sshkey_free(key); 1548 continue; 1549 } 1550 /* Find matching private key */ 1551 for (j = 0; j < options.num_host_key_files; j++) { 1552 if (sshkey_equal_public(key, 1553 sensitive_data.host_pubkeys[j])) { 1554 sensitive_data.host_certificates[j] = key; 1555 break; 1556 } 1557 } 1558 if (j >= options.num_host_key_files) { 1559 error("No matching private key for certificate: %s", 1560 options.host_cert_files[i]); 1561 sshkey_free(key); 1562 continue; 1563 } 1564 sensitive_data.host_certificates[j] = key; 1565 debug("host certificate: #%u type %d %s", j, key->type, 1566 sshkey_type(key)); 1567 } 1568 1569 /* Ensure privsep directory is correctly configured. */ 1570 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1571 fatal("Privilege separation user %s does not exist", 1572 SSH_PRIVSEP_USER); 1573 endpwent(); 1574 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &sb) == -1) || 1575 (S_ISDIR(sb.st_mode) == 0)) 1576 fatal("Missing privilege separation directory: %s", 1577 _PATH_PRIVSEP_CHROOT_DIR); 1578 if (sb.st_uid != 0 || (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1579 fatal("%s must be owned by root and not group or " 1580 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1581 1582 if (test_flag > 1) 1583 print_config(&connection_info); 1584 1585 /* Configuration looks good, so exit if in test mode. */ 1586 if (test_flag) 1587 exit(0); 1588 1589 /* Prepare arguments for sshd-session */ 1590 if (rexec_argc < 0) 1591 fatal("rexec_argc %d < 0", rexec_argc); 1592 rexec_argv = xcalloc(rexec_argc + 3, sizeof(char *)); 1593 /* Point to the sshd-session binary instead of sshd */ 1594 rexec_argv[0] = options.sshd_session_path; 1595 for (i = 1; i < (u_int)rexec_argc; i++) { 1596 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1597 rexec_argv[i] = saved_argv[i]; 1598 } 1599 rexec_argv[rexec_argc++] = __UNCONST("-R"); 1600 rexec_argv[rexec_argc] = NULL; 1601 if (stat(rexec_argv[0], &sb) != 0 || !(sb.st_mode & (S_IXOTH|S_IXUSR))) 1602 fatal("%s does not exist or is not executable", rexec_argv[0]); 1603 debug3("using %s for re-exec", rexec_argv[0]); 1604 1605 listener_proctitle = prepare_proctitle(ac, av); 1606 1607 /* Ensure that umask disallows at least group and world write */ 1608 new_umask = umask(0077) | 0022; 1609 (void) umask(new_umask); 1610 1611 /* Initialize the log (it is reinitialized below in case we forked). */ 1612 if (debug_flag && !inetd_flag) 1613 log_stderr = 1; 1614 log_init(__progname, options.log_level, 1615 options.log_facility, log_stderr); 1616 for (i = 0; i < options.num_log_verbose; i++) 1617 log_verbose_add(options.log_verbose[i]); 1618 1619 /* 1620 * If not in debugging mode, not started from inetd and not already 1621 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1622 * terminal, and fork. The original process exits. 1623 */ 1624 already_daemon = daemonized(); 1625 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1626 1627 if (daemon(0, 0) == -1) 1628 fatal("daemon() failed: %.200s", strerror(errno)); 1629 1630 disconnect_controlling_tty(); 1631 } 1632 /* Reinitialize the log (because of the fork above). */ 1633 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1634 1635 /* 1636 * Chdir to the root directory so that the current disk can be 1637 * unmounted if desired. 1638 */ 1639 if (chdir("/") == -1) 1640 error("chdir(\"/\"): %s", strerror(errno)); 1641 1642 /* ignore SIGPIPE */ 1643 ssh_signal(SIGPIPE, SIG_IGN); 1644 1645 /* Get a connection, either from inetd or a listening TCP socket */ 1646 if (inetd_flag) { 1647 /* Send configuration to ancestor sshd-session process */ 1648 if (socketpair(AF_UNIX, SOCK_STREAM, 0, config_s) == -1) 1649 fatal("socketpair: %s", strerror(errno)); 1650 send_rexec_state(config_s[0], cfg); 1651 close(config_s[0]); 1652 } else { 1653 server_listen(); 1654 1655 ssh_signal(SIGHUP, sighup_handler); 1656 ssh_signal(SIGCHLD, main_sigchld_handler); 1657 ssh_signal(SIGTERM, sigterm_handler); 1658 ssh_signal(SIGQUIT, sigterm_handler); 1659 ssh_signal(SIGINFO, siginfo_handler); 1660 1661 /* 1662 * Write out the pid file after the sigterm handler 1663 * is setup and the listen sockets are bound 1664 */ 1665 if (options.pid_file != NULL && !debug_flag) { 1666 FILE *f = fopen(options.pid_file, "w"); 1667 1668 if (f == NULL) { 1669 error("Couldn't create pid file \"%s\": %s", 1670 options.pid_file, strerror(errno)); 1671 } else { 1672 fprintf(f, "%ld\n", (long) getpid()); 1673 fclose(f); 1674 } 1675 } 1676 1677 /* Accept a connection and return in a forked child */ 1678 server_accept_loop(&sock_in, &sock_out, 1679 &newsock, config_s, log_stderr); 1680 } 1681 1682 /* This is the child processing a new connection. */ 1683 setproctitle("%s", "[accepted]"); 1684 1685 /* 1686 * Create a new session and process group since the 4.4BSD 1687 * setlogin() affects the entire process group. We don't 1688 * want the child to be able to affect the parent. 1689 */ 1690 if (!debug_flag && !inetd_flag && setsid() == -1) 1691 error("setsid: %.100s", strerror(errno)); 1692 1693 debug("rexec start in %d out %d newsock %d pipe %d sock %d/%d", 1694 sock_in, sock_out, newsock, startup_pipe, config_s[0], config_s[1]); 1695 if (!inetd_flag) { 1696 if (dup2(newsock, STDIN_FILENO) == -1) 1697 fatal("dup2 stdin: %s", strerror(errno)); 1698 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1) 1699 fatal("dup2 stdout: %s", strerror(errno)); 1700 if (newsock > STDOUT_FILENO) 1701 close(newsock); 1702 } 1703 if (config_s[1] != REEXEC_CONFIG_PASS_FD) { 1704 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1) 1705 fatal("dup2 config_s: %s", strerror(errno)); 1706 close(config_s[1]); 1707 } 1708 if (startup_pipe == -1) 1709 close(REEXEC_STARTUP_PIPE_FD); 1710 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1711 if (dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD) == -1) 1712 fatal("dup2 startup_p: %s", strerror(errno)); 1713 close(startup_pipe); 1714 } 1715 log_redirect_stderr_to(NULL); 1716 closefrom(REEXEC_MIN_FREE_FD); 1717 1718 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1719 execv(rexec_argv[0], rexec_argv); 1720 1721 fatal("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1722 } 1723 1724 /* server specific fatal cleanup */ 1725 void 1726 cleanup_exit(int i) 1727 { 1728 _exit(i); 1729 } 1730