1 /* $OpenBSD: sshd.c,v 1.612 2024/09/15 01:11:26 djm Exp $ */ 2 /* 3 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 4 * Copyright (c) 2002 Niels Provos. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/ioctl.h> 31 #include <sys/mman.h> 32 #include <sys/socket.h> 33 #ifdef HAVE_SYS_STAT_H 34 # include <sys/stat.h> 35 #endif 36 #ifdef HAVE_SYS_TIME_H 37 # include <sys/time.h> 38 #endif 39 #include "openbsd-compat/sys-tree.h" 40 #include "openbsd-compat/sys-queue.h" 41 #include <sys/wait.h> 42 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <netdb.h> 46 #ifdef HAVE_PATHS_H 47 #include <paths.h> 48 #endif 49 #include <grp.h> 50 #ifdef HAVE_POLL_H 51 #include <poll.h> 52 #endif 53 #include <pwd.h> 54 #include <signal.h> 55 #include <stdarg.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <unistd.h> 60 #include <limits.h> 61 62 #ifdef WITH_OPENSSL 63 #include <openssl/evp.h> 64 #include <openssl/rand.h> 65 #include "openbsd-compat/openssl-compat.h" 66 #endif 67 68 #ifdef HAVE_SECUREWARE 69 #include <sys/security.h> 70 #include <prot.h> 71 #endif 72 73 #ifdef __FreeBSD__ 74 #include <resolv.h> 75 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 76 #include <gssapi/gssapi.h> 77 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 78 #include <gssapi.h> 79 #endif 80 #endif 81 82 #include "xmalloc.h" 83 #include "ssh.h" 84 #include "sshpty.h" 85 #include "log.h" 86 #include "sshbuf.h" 87 #include "misc.h" 88 #include "servconf.h" 89 #include "compat.h" 90 #include "digest.h" 91 #include "sshkey.h" 92 #include "authfile.h" 93 #include "pathnames.h" 94 #include "canohost.h" 95 #include "hostfile.h" 96 #include "auth.h" 97 #include "authfd.h" 98 #include "msg.h" 99 #include "version.h" 100 #include "ssherr.h" 101 #include "sk-api.h" 102 #include "addr.h" 103 #include "srclimit.h" 104 #include "blacklist_client.h" 105 106 #ifdef LIBWRAP 107 #include <tcpd.h> 108 #include <syslog.h> 109 #endif /* LIBWRAP */ 110 111 /* Re-exec fds */ 112 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 113 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 114 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 115 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 116 117 extern char *__progname; 118 119 /* Server configuration options. */ 120 ServerOptions options; 121 122 /* 123 * Debug mode flag. This can be set on the command line. If debug 124 * mode is enabled, extra debugging output will be sent to the system 125 * log, the daemon will not go to background, and will exit after processing 126 * the first connection. 127 */ 128 int debug_flag = 0; 129 130 /* Saved arguments to main(). */ 131 static char **saved_argv; 132 static int saved_argc; 133 134 /* 135 * The sockets that the server is listening; this is used in the SIGHUP 136 * signal handler. 137 */ 138 #define MAX_LISTEN_SOCKS 16 139 static int listen_socks[MAX_LISTEN_SOCKS]; 140 static int num_listen_socks = 0; 141 142 /* 143 * Any really sensitive data in the application is contained in this 144 * structure. The idea is that this structure could be locked into memory so 145 * that the pages do not get written into swap. However, there are some 146 * problems. The private key contains BIGNUMs, and we do not (in principle) 147 * have access to the internals of them, and locking just the structure is 148 * not very useful. Currently, memory locking is not implemented. 149 */ 150 struct { 151 struct sshkey **host_keys; /* all private host keys */ 152 struct sshkey **host_pubkeys; /* all public host keys */ 153 struct sshkey **host_certificates; /* all public host certificates */ 154 int have_ssh2_key; 155 } sensitive_data; 156 157 /* This is set to true when a signal is received. */ 158 static volatile sig_atomic_t received_siginfo = 0; 159 static volatile sig_atomic_t received_sigchld = 0; 160 static volatile sig_atomic_t received_sighup = 0; 161 static volatile sig_atomic_t received_sigterm = 0; 162 163 /* record remote hostname or ip */ 164 u_int utmp_len = HOST_NAME_MAX+1; 165 166 /* 167 * The early_child/children array below is used for tracking children of the 168 * listening sshd process early in their lifespans, before they have 169 * completed authentication. This tracking is needed for four things: 170 * 171 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 172 * connections. 173 * 2) Avoiding a race condition for SIGHUP processing, where child processes 174 * may have listen_socks open that could collide with main listener process 175 * after it restarts. 176 * 3) Ensuring that rexec'd sshd processes have received their initial state 177 * from the parent listen process before handling SIGHUP. 178 * 4) Tracking and logging unsuccessful exits from the preauth sshd monitor, 179 * including and especially those for LoginGraceTime timeouts. 180 * 181 * Child processes signal that they have completed closure of the listen_socks 182 * and (if applicable) received their rexec state by sending a char over their 183 * sock. 184 * 185 * Child processes signal that authentication has completed by sending a 186 * second char over the socket before closing it, otherwise the listener will 187 * continue tracking the child (and using up a MaxStartups slot) until the 188 * preauth subprocess exits, whereupon the listener will log its exit status. 189 * preauth processes will exit with a status of EXIT_LOGIN_GRACE to indicate 190 * they did not authenticate before the LoginGraceTime alarm fired. 191 */ 192 struct early_child { 193 int pipefd; 194 int early; /* Indicates child closed listener */ 195 char *id; /* human readable connection identifier */ 196 pid_t pid; 197 struct xaddr addr; 198 int have_addr; 199 int status, have_status; 200 }; 201 static struct early_child *children; 202 static int children_active; 203 static int startup_pipe = -1; /* in child */ 204 205 /* sshd_config buffer */ 206 struct sshbuf *cfg; 207 208 /* Included files from the configuration file */ 209 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 210 211 /* message to be displayed after login */ 212 struct sshbuf *loginmsg; 213 214 /* Unprivileged user */ 215 struct passwd *privsep_pw = NULL; 216 217 static char *listener_proctitle; 218 219 /* 220 * Close all listening sockets 221 */ 222 static void 223 close_listen_socks(void) 224 { 225 int i; 226 227 for (i = 0; i < num_listen_socks; i++) 228 close(listen_socks[i]); 229 num_listen_socks = 0; 230 } 231 232 /* Allocate and initialise the children array */ 233 static void 234 child_alloc(void) 235 { 236 int i; 237 238 children = xcalloc(options.max_startups, sizeof(*children)); 239 for (i = 0; i < options.max_startups; i++) { 240 children[i].pipefd = -1; 241 children[i].pid = -1; 242 } 243 } 244 245 /* Register a new connection in the children array; child pid comes later */ 246 static struct early_child * 247 child_register(int pipefd, int sockfd) 248 { 249 int i, lport, rport; 250 char *laddr = NULL, *raddr = NULL; 251 struct early_child *child = NULL; 252 struct sockaddr_storage addr; 253 socklen_t addrlen = sizeof(addr); 254 struct sockaddr *sa = (struct sockaddr *)&addr; 255 256 for (i = 0; i < options.max_startups; i++) { 257 if (children[i].pipefd != -1 || children[i].pid > 0) 258 continue; 259 child = &(children[i]); 260 break; 261 } 262 if (child == NULL) { 263 fatal_f("error: accepted connection when all %d child " 264 " slots full", options.max_startups); 265 } 266 child->pipefd = pipefd; 267 child->early = 1; 268 /* record peer address, if available */ 269 if (getpeername(sockfd, sa, &addrlen) == 0 && 270 addr_sa_to_xaddr(sa, addrlen, &child->addr) == 0) 271 child->have_addr = 1; 272 /* format peer address string for logs */ 273 if ((lport = get_local_port(sockfd)) == 0 || 274 (rport = get_peer_port(sockfd)) == 0) { 275 /* Not a TCP socket */ 276 raddr = get_peer_ipaddr(sockfd); 277 xasprintf(&child->id, "connection from %s", raddr); 278 } else { 279 laddr = get_local_ipaddr(sockfd); 280 raddr = get_peer_ipaddr(sockfd); 281 xasprintf(&child->id, "connection from %s to %s", raddr, laddr); 282 } 283 free(laddr); 284 free(raddr); 285 if (++children_active > options.max_startups) 286 fatal_f("internal error: more children than max_startups"); 287 288 return child; 289 } 290 291 /* 292 * Finally free a child entry. Don't call this directly. 293 */ 294 static void 295 child_finish(struct early_child *child) 296 { 297 if (children_active == 0) 298 fatal_f("internal error: children_active underflow"); 299 if (child->pipefd != -1) 300 close(child->pipefd); 301 free(child->id); 302 memset(child, '\0', sizeof(*child)); 303 child->pipefd = -1; 304 child->pid = -1; 305 children_active--; 306 } 307 308 /* 309 * Close a child's pipe. This will not stop tracking the child immediately 310 * (it will still be tracked for waitpid()) unless force_final is set, or 311 * child has already exited. 312 */ 313 static void 314 child_close(struct early_child *child, int force_final, int quiet) 315 { 316 if (!quiet) 317 debug_f("enter%s", force_final ? " (forcing)" : ""); 318 if (child->pipefd != -1) { 319 close(child->pipefd); 320 child->pipefd = -1; 321 } 322 if (child->pid == -1 || force_final) 323 child_finish(child); 324 } 325 326 /* Record a child exit. Safe to call from signal handlers */ 327 static void 328 child_exit(pid_t pid, int status) 329 { 330 int i; 331 332 if (children == NULL || pid <= 0) 333 return; 334 for (i = 0; i < options.max_startups; i++) { 335 if (children[i].pid == pid) { 336 children[i].have_status = 1; 337 children[i].status = status; 338 break; 339 } 340 } 341 } 342 343 /* 344 * Reap a child entry that has exited, as previously flagged 345 * using child_exit(). 346 * Handles logging of exit condition and will finalise the child if its pipe 347 * had already been closed. 348 */ 349 static void 350 child_reap(struct early_child *child) 351 { 352 LogLevel level = SYSLOG_LEVEL_DEBUG1; 353 int was_crash, penalty_type = SRCLIMIT_PENALTY_NONE; 354 355 /* Log exit information */ 356 if (WIFSIGNALED(child->status)) { 357 /* 358 * Increase logging for signals potentially associated 359 * with serious conditions. 360 */ 361 if ((was_crash = signal_is_crash(WTERMSIG(child->status)))) 362 level = SYSLOG_LEVEL_ERROR; 363 do_log2(level, "session process %ld for %s killed by " 364 "signal %d%s", (long)child->pid, child->id, 365 WTERMSIG(child->status), child->early ? " (early)" : ""); 366 if (was_crash) 367 penalty_type = SRCLIMIT_PENALTY_CRASH; 368 } else if (!WIFEXITED(child->status)) { 369 penalty_type = SRCLIMIT_PENALTY_CRASH; 370 error("session process %ld for %s terminated abnormally, " 371 "status=0x%x%s", (long)child->pid, child->id, child->status, 372 child->early ? " (early)" : ""); 373 } else { 374 /* Normal exit. We care about the status */ 375 switch (WEXITSTATUS(child->status)) { 376 case 0: 377 debug3_f("preauth child %ld for %s completed " 378 "normally %s", (long)child->pid, child->id, 379 child->early ? " (early)" : ""); 380 break; 381 case EXIT_LOGIN_GRACE: 382 penalty_type = SRCLIMIT_PENALTY_GRACE_EXCEEDED; 383 logit("Timeout before authentication for %s, " 384 "pid = %ld%s", child->id, (long)child->pid, 385 child->early ? " (early)" : ""); 386 break; 387 case EXIT_CHILD_CRASH: 388 penalty_type = SRCLIMIT_PENALTY_CRASH; 389 logit("Session process %ld unpriv child crash for %s%s", 390 (long)child->pid, child->id, 391 child->early ? " (early)" : ""); 392 break; 393 case EXIT_AUTH_ATTEMPTED: 394 penalty_type = SRCLIMIT_PENALTY_AUTHFAIL; 395 debug_f("preauth child %ld for %s exited " 396 "after unsuccessful auth attempt %s", 397 (long)child->pid, child->id, 398 child->early ? " (early)" : ""); 399 break; 400 case EXIT_CONFIG_REFUSED: 401 penalty_type = SRCLIMIT_PENALTY_REFUSECONNECTION; 402 debug_f("preauth child %ld for %s prohibited by" 403 "RefuseConnection %s", 404 (long)child->pid, child->id, 405 child->early ? " (early)" : ""); 406 break; 407 default: 408 penalty_type = SRCLIMIT_PENALTY_NOAUTH; 409 debug_f("preauth child %ld for %s exited " 410 "with status %d%s", (long)child->pid, child->id, 411 WEXITSTATUS(child->status), 412 child->early ? " (early)" : ""); 413 break; 414 } 415 } 416 417 if (child->have_addr) 418 srclimit_penalise(&child->addr, penalty_type); 419 420 child->pid = -1; 421 child->have_status = 0; 422 if (child->pipefd == -1) 423 child_finish(child); 424 } 425 426 /* Reap all children that have exited; called after SIGCHLD */ 427 static void 428 child_reap_all_exited(void) 429 { 430 int i; 431 pid_t pid; 432 int status; 433 434 if (children == NULL) 435 return; 436 437 for (;;) { 438 if ((pid = waitpid(-1, &status, WNOHANG)) == 0) 439 break; 440 else if (pid == -1) { 441 if (errno == EINTR || errno == EAGAIN) 442 continue; 443 if (errno != ECHILD) 444 error_f("waitpid: %s", strerror(errno)); 445 break; 446 } 447 child_exit(pid, status); 448 } 449 450 for (i = 0; i < options.max_startups; i++) { 451 if (!children[i].have_status) 452 continue; 453 child_reap(&(children[i])); 454 } 455 } 456 457 static void 458 close_startup_pipes(void) 459 { 460 int i; 461 462 if (children == NULL) 463 return; 464 for (i = 0; i < options.max_startups; i++) { 465 if (children[i].pipefd != -1) 466 child_close(&(children[i]), 1, 1); 467 } 468 } 469 470 /* Called after SIGINFO */ 471 static void 472 show_info(void) 473 { 474 int i; 475 476 /* XXX print listening sockets here too */ 477 if (children == NULL) 478 return; 479 logit("%d active startups", children_active); 480 for (i = 0; i < options.max_startups; i++) { 481 if (children[i].pipefd == -1 && children[i].pid <= 0) 482 continue; 483 logit("child %d: fd=%d pid=%ld %s%s", i, children[i].pipefd, 484 (long)children[i].pid, children[i].id, 485 children[i].early ? " (early)" : ""); 486 } 487 srclimit_penalty_info(); 488 } 489 490 /* 491 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 492 * the effect is to reread the configuration file (and to regenerate 493 * the server key). 494 */ 495 496 static void 497 sighup_handler(int sig) 498 { 499 received_sighup = 1; 500 } 501 502 /* 503 * Called from the main program after receiving SIGHUP. 504 * Restarts the server. 505 */ 506 static void 507 sighup_restart(void) 508 { 509 logit("Received SIGHUP; restarting."); 510 if (options.pid_file != NULL) 511 unlink(options.pid_file); 512 platform_pre_restart(); 513 close_listen_socks(); 514 close_startup_pipes(); 515 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 516 execv(saved_argv[0], saved_argv); 517 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 518 strerror(errno)); 519 exit(1); 520 } 521 522 /* 523 * Generic signal handler for terminating signals in the master daemon. 524 */ 525 static void 526 sigterm_handler(int sig) 527 { 528 received_sigterm = sig; 529 } 530 531 #ifdef SIGINFO 532 static void 533 siginfo_handler(int sig) 534 { 535 received_siginfo = 1; 536 } 537 #endif 538 539 static void 540 main_sigchld_handler(int sig) 541 { 542 received_sigchld = 1; 543 } 544 545 /* 546 * returns 1 if connection should be dropped, 0 otherwise. 547 * dropping starts at connection #max_startups_begin with a probability 548 * of (max_startups_rate/100). the probability increases linearly until 549 * all connections are dropped for startups > max_startups 550 */ 551 static int 552 should_drop_connection(int startups) 553 { 554 int p, r; 555 556 if (startups < options.max_startups_begin) 557 return 0; 558 if (startups >= options.max_startups) 559 return 1; 560 if (options.max_startups_rate == 100) 561 return 1; 562 563 p = 100 - options.max_startups_rate; 564 p *= startups - options.max_startups_begin; 565 p /= options.max_startups - options.max_startups_begin; 566 p += options.max_startups_rate; 567 r = arc4random_uniform(100); 568 569 debug_f("p %d, r %d", p, r); 570 return (r < p) ? 1 : 0; 571 } 572 573 /* 574 * Check whether connection should be accepted by MaxStartups or for penalty. 575 * Returns 0 if the connection is accepted. If the connection is refused, 576 * returns 1 and attempts to send notification to client. 577 * Logs when the MaxStartups condition is entered or exited, and periodically 578 * while in that state. 579 */ 580 static int 581 drop_connection(int sock, int startups, int notify_pipe) 582 { 583 char *laddr, *raddr; 584 const char *reason = NULL, msg[] = "Not allowed at this time\r\n"; 585 static time_t last_drop, first_drop; 586 static u_int ndropped; 587 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 588 time_t now; 589 590 if (!srclimit_penalty_check_allow(sock, &reason)) { 591 drop_level = SYSLOG_LEVEL_INFO; 592 goto handle; 593 } 594 595 now = monotime(); 596 if (!should_drop_connection(startups) && 597 srclimit_check_allow(sock, notify_pipe) == 1) { 598 if (last_drop != 0 && 599 startups < options.max_startups_begin - 1) { 600 /* XXX maybe need better hysteresis here */ 601 logit("exited MaxStartups throttling after %s, " 602 "%u connections dropped", 603 fmt_timeframe(now - first_drop), ndropped); 604 last_drop = 0; 605 } 606 return 0; 607 } 608 609 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 610 if (last_drop == 0) { 611 error("beginning MaxStartups throttling"); 612 drop_level = SYSLOG_LEVEL_INFO; 613 first_drop = now; 614 ndropped = 0; 615 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 616 /* Periodic logs */ 617 error("in MaxStartups throttling for %s, " 618 "%u connections dropped", 619 fmt_timeframe(now - first_drop), ndropped + 1); 620 drop_level = SYSLOG_LEVEL_INFO; 621 } 622 last_drop = now; 623 ndropped++; 624 reason = "past Maxstartups"; 625 626 handle: 627 laddr = get_local_ipaddr(sock); 628 raddr = get_peer_ipaddr(sock); 629 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d %s", 630 startups, 631 raddr, get_peer_port(sock), 632 laddr, get_local_port(sock), 633 reason); 634 free(laddr); 635 free(raddr); 636 /* best-effort notification to client */ 637 (void)write(sock, msg, sizeof(msg) - 1); 638 return 1; 639 } 640 641 static void 642 usage(void) 643 { 644 if (options.version_addendum != NULL && 645 *options.version_addendum != '\0') 646 fprintf(stderr, "%s %s, %s\n", 647 SSH_RELEASE, 648 options.version_addendum, SSH_OPENSSL_VERSION); 649 else 650 fprintf(stderr, "%s, %s\n", 651 SSH_RELEASE, SSH_OPENSSL_VERSION); 652 fprintf(stderr, 653 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n" 654 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 655 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 656 ); 657 exit(1); 658 } 659 660 static struct sshbuf * 661 pack_hostkeys(void) 662 { 663 struct sshbuf *keybuf = NULL, *hostkeys = NULL; 664 int r; 665 u_int i; 666 667 if ((keybuf = sshbuf_new()) == NULL || 668 (hostkeys = sshbuf_new()) == NULL) 669 fatal_f("sshbuf_new failed"); 670 671 /* pack hostkeys into a string. Empty key slots get empty strings */ 672 for (i = 0; i < options.num_host_key_files; i++) { 673 /* private key */ 674 sshbuf_reset(keybuf); 675 if (sensitive_data.host_keys[i] != NULL && 676 (r = sshkey_private_serialize(sensitive_data.host_keys[i], 677 keybuf)) != 0) 678 fatal_fr(r, "serialize hostkey private"); 679 if ((r = sshbuf_put_stringb(hostkeys, keybuf)) != 0) 680 fatal_fr(r, "compose hostkey private"); 681 /* public key */ 682 if (sensitive_data.host_pubkeys[i] != NULL) { 683 if ((r = sshkey_puts(sensitive_data.host_pubkeys[i], 684 hostkeys)) != 0) 685 fatal_fr(r, "compose hostkey public"); 686 } else { 687 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 688 fatal_fr(r, "compose hostkey empty public"); 689 } 690 /* cert */ 691 if (sensitive_data.host_certificates[i] != NULL) { 692 if ((r = sshkey_puts( 693 sensitive_data.host_certificates[i], 694 hostkeys)) != 0) 695 fatal_fr(r, "compose host cert"); 696 } else { 697 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 698 fatal_fr(r, "compose host cert empty"); 699 } 700 } 701 702 sshbuf_free(keybuf); 703 return hostkeys; 704 } 705 706 static void 707 send_rexec_state(int fd, struct sshbuf *conf) 708 { 709 struct sshbuf *m = NULL, *inc = NULL, *hostkeys = NULL; 710 struct include_item *item = NULL; 711 int r, sz; 712 713 debug3_f("entering fd = %d config len %zu", fd, 714 sshbuf_len(conf)); 715 716 if ((m = sshbuf_new()) == NULL || 717 (inc = sshbuf_new()) == NULL) 718 fatal_f("sshbuf_new failed"); 719 720 /* pack includes into a string */ 721 TAILQ_FOREACH(item, &includes, entry) { 722 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 723 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 724 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 725 fatal_fr(r, "compose includes"); 726 } 727 728 hostkeys = pack_hostkeys(); 729 730 /* 731 * Protocol from reexec master to child: 732 * string configuration 733 * uint64 timing_secret 734 * string host_keys[] { 735 * string private_key 736 * string public_key 737 * string certificate 738 * } 739 * string included_files[] { 740 * string selector 741 * string filename 742 * string contents 743 * } 744 */ 745 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 746 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 || 747 (r = sshbuf_put_stringb(m, hostkeys)) != 0 || 748 (r = sshbuf_put_stringb(m, inc)) != 0) 749 fatal_fr(r, "compose config"); 750 751 /* We need to fit the entire message inside the socket send buffer */ 752 sz = ROUNDUP(sshbuf_len(m) + 5, 16*1024); 753 if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sz, sizeof sz) == -1) 754 fatal_f("setsockopt SO_SNDBUF: %s", strerror(errno)); 755 756 if (ssh_msg_send(fd, 0, m) == -1) 757 error_f("ssh_msg_send failed"); 758 759 sshbuf_free(m); 760 sshbuf_free(inc); 761 sshbuf_free(hostkeys); 762 763 debug3_f("done"); 764 } 765 766 /* 767 * Listen for TCP connections 768 */ 769 static void 770 listen_on_addrs(struct listenaddr *la) 771 { 772 int ret, listen_sock; 773 struct addrinfo *ai; 774 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 775 776 for (ai = la->addrs; ai; ai = ai->ai_next) { 777 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 778 continue; 779 if (num_listen_socks >= MAX_LISTEN_SOCKS) 780 fatal("Too many listen sockets. " 781 "Enlarge MAX_LISTEN_SOCKS"); 782 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 783 ntop, sizeof(ntop), strport, sizeof(strport), 784 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 785 error("getnameinfo failed: %.100s", 786 ssh_gai_strerror(ret)); 787 continue; 788 } 789 /* Create socket for listening. */ 790 listen_sock = socket(ai->ai_family, ai->ai_socktype, 791 ai->ai_protocol); 792 if (listen_sock == -1) { 793 /* kernel may not support ipv6 */ 794 verbose("socket: %.100s", strerror(errno)); 795 continue; 796 } 797 if (set_nonblock(listen_sock) == -1) { 798 close(listen_sock); 799 continue; 800 } 801 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 802 verbose("socket: CLOEXEC: %s", strerror(errno)); 803 close(listen_sock); 804 continue; 805 } 806 /* Socket options */ 807 set_reuseaddr(listen_sock); 808 if (la->rdomain != NULL && 809 set_rdomain(listen_sock, la->rdomain) == -1) { 810 close(listen_sock); 811 continue; 812 } 813 814 /* Only communicate in IPv6 over AF_INET6 sockets. */ 815 if (ai->ai_family == AF_INET6) 816 sock_set_v6only(listen_sock); 817 818 debug("Bind to port %s on %s.", strport, ntop); 819 820 /* Bind the socket to the desired port. */ 821 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 822 error("Bind to port %s on %s failed: %.200s.", 823 strport, ntop, strerror(errno)); 824 close(listen_sock); 825 continue; 826 } 827 listen_socks[num_listen_socks] = listen_sock; 828 num_listen_socks++; 829 830 /* Start listening on the port. */ 831 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 832 fatal("listen on [%s]:%s: %.100s", 833 ntop, strport, strerror(errno)); 834 logit("Server listening on %s port %s%s%s.", 835 ntop, strport, 836 la->rdomain == NULL ? "" : " rdomain ", 837 la->rdomain == NULL ? "" : la->rdomain); 838 } 839 } 840 841 static void 842 server_listen(void) 843 { 844 u_int i; 845 846 /* Initialise per-source limit tracking. */ 847 srclimit_init(options.max_startups, 848 options.per_source_max_startups, 849 options.per_source_masklen_ipv4, 850 options.per_source_masklen_ipv6, 851 &options.per_source_penalty, 852 options.per_source_penalty_exempt); 853 854 for (i = 0; i < options.num_listen_addrs; i++) { 855 listen_on_addrs(&options.listen_addrs[i]); 856 freeaddrinfo(options.listen_addrs[i].addrs); 857 free(options.listen_addrs[i].rdomain); 858 memset(&options.listen_addrs[i], 0, 859 sizeof(options.listen_addrs[i])); 860 } 861 free(options.listen_addrs); 862 options.listen_addrs = NULL; 863 options.num_listen_addrs = 0; 864 865 if (!num_listen_socks) 866 fatal("Cannot bind any address."); 867 } 868 869 /* 870 * The main TCP accept loop. Note that, for the non-debug case, returns 871 * from this function are in a forked subprocess. 872 */ 873 static void 874 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s, 875 int log_stderr) 876 { 877 struct pollfd *pfd = NULL; 878 int i, ret, npfd; 879 int oactive = -1, listening = 0, lameduck = 0; 880 int startup_p[2] = { -1 , -1 }, *startup_pollfd; 881 char c = 0; 882 struct sockaddr_storage from; 883 struct early_child *child; 884 socklen_t fromlen; 885 u_char rnd[256]; 886 sigset_t nsigset, osigset; 887 #ifdef LIBWRAP 888 struct request_info req; 889 890 request_init(&req, RQ_DAEMON, __progname, 0); 891 #endif 892 893 /* pipes connected to unauthenticated child sshd processes */ 894 child_alloc(); 895 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 896 897 /* 898 * Prepare signal mask that we use to block signals that might set 899 * received_sigterm/hup/chld/info, so that we are guaranteed 900 * to immediately wake up the ppoll if a signal is received after 901 * the flag is checked. 902 */ 903 sigemptyset(&nsigset); 904 sigaddset(&nsigset, SIGHUP); 905 sigaddset(&nsigset, SIGCHLD); 906 #ifdef SIGINFO 907 sigaddset(&nsigset, SIGINFO); 908 #endif 909 sigaddset(&nsigset, SIGTERM); 910 sigaddset(&nsigset, SIGQUIT); 911 912 /* sized for worst-case */ 913 pfd = xcalloc(num_listen_socks + options.max_startups, 914 sizeof(struct pollfd)); 915 916 /* 917 * Stay listening for connections until the system crashes or 918 * the daemon is killed with a signal. 919 */ 920 for (;;) { 921 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 922 if (received_sigterm) { 923 logit("Received signal %d; terminating.", 924 (int) received_sigterm); 925 close_listen_socks(); 926 if (options.pid_file != NULL) 927 unlink(options.pid_file); 928 exit(received_sigterm == SIGTERM ? 0 : 255); 929 } 930 if (received_sigchld) { 931 child_reap_all_exited(); 932 received_sigchld = 0; 933 } 934 if (received_siginfo) { 935 show_info(); 936 received_siginfo = 0; 937 } 938 if (oactive != children_active) { 939 setproctitle("%s [listener] %d of %d-%d startups", 940 listener_proctitle, children_active, 941 options.max_startups_begin, options.max_startups); 942 oactive = children_active; 943 } 944 if (received_sighup) { 945 if (!lameduck) { 946 debug("Received SIGHUP; waiting for children"); 947 close_listen_socks(); 948 lameduck = 1; 949 } 950 if (listening <= 0) { 951 sigprocmask(SIG_SETMASK, &osigset, NULL); 952 sighup_restart(); 953 } 954 } 955 956 for (i = 0; i < num_listen_socks; i++) { 957 pfd[i].fd = listen_socks[i]; 958 pfd[i].events = POLLIN; 959 } 960 npfd = num_listen_socks; 961 for (i = 0; i < options.max_startups; i++) { 962 startup_pollfd[i] = -1; 963 if (children[i].pipefd != -1) { 964 pfd[npfd].fd = children[i].pipefd; 965 pfd[npfd].events = POLLIN; 966 startup_pollfd[i] = npfd++; 967 } 968 } 969 970 /* Wait until a connection arrives or a child exits. */ 971 ret = ppoll(pfd, npfd, NULL, &osigset); 972 if (ret == -1 && errno != EINTR) { 973 error("ppoll: %.100s", strerror(errno)); 974 if (errno == EINVAL) 975 cleanup_exit(1); /* can't recover */ 976 } 977 sigprocmask(SIG_SETMASK, &osigset, NULL); 978 if (ret == -1) 979 continue; 980 981 for (i = 0; i < options.max_startups; i++) { 982 if (children[i].pipefd == -1 || 983 startup_pollfd[i] == -1 || 984 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 985 continue; 986 switch (read(children[i].pipefd, &c, sizeof(c))) { 987 case -1: 988 if (errno == EINTR || errno == EAGAIN) 989 continue; 990 if (errno != EPIPE) { 991 error_f("startup pipe %d (fd=%d): " 992 "read %s", i, children[i].pipefd, 993 strerror(errno)); 994 } 995 /* FALLTHROUGH */ 996 case 0: 997 /* child exited preauth */ 998 if (children[i].early) 999 listening--; 1000 srclimit_done(children[i].pipefd); 1001 child_close(&(children[i]), 0, 0); 1002 break; 1003 case 1: 1004 if (children[i].early && c == '\0') { 1005 /* child has finished preliminaries */ 1006 listening--; 1007 children[i].early = 0; 1008 debug2_f("child %lu for %s received " 1009 "config", (long)children[i].pid, 1010 children[i].id); 1011 } else if (!children[i].early && c == '\001') { 1012 /* child has completed auth */ 1013 debug2_f("child %lu for %s auth done", 1014 (long)children[i].pid, 1015 children[i].id); 1016 child_close(&(children[i]), 1, 0); 1017 } else { 1018 error_f("unexpected message 0x%02x " 1019 "child %ld for %s in state %d", 1020 (int)c, (long)children[i].pid, 1021 children[i].id, children[i].early); 1022 } 1023 break; 1024 } 1025 } 1026 for (i = 0; i < num_listen_socks; i++) { 1027 if (!(pfd[i].revents & POLLIN)) 1028 continue; 1029 fromlen = sizeof(from); 1030 *newsock = accept(listen_socks[i], 1031 (struct sockaddr *)&from, &fromlen); 1032 if (*newsock == -1) { 1033 if (errno != EINTR && errno != EWOULDBLOCK && 1034 errno != ECONNABORTED && errno != EAGAIN) 1035 error("accept: %.100s", 1036 strerror(errno)); 1037 if (errno == EMFILE || errno == ENFILE) 1038 usleep(100 * 1000); 1039 continue; 1040 } 1041 #ifdef LIBWRAP 1042 /* Check whether logins are denied from this host. */ 1043 request_set(&req, RQ_FILE, *newsock, 1044 RQ_CLIENT_NAME, "", RQ_CLIENT_ADDR, "", 0); 1045 sock_host(&req); 1046 if (!hosts_access(&req)) { 1047 const struct linger l = { .l_onoff = 1, 1048 .l_linger = 0 }; 1049 1050 (void )setsockopt(*newsock, SOL_SOCKET, 1051 SO_LINGER, &l, sizeof(l)); 1052 (void )close(*newsock); 1053 /* 1054 * Mimic message from libwrap's refuse() as 1055 * precisely as we can afford. The authentic 1056 * message prints the IP address and the 1057 * hostname it resolves to in parentheses. If 1058 * the IP address cannot be resolved to a 1059 * hostname, the IP address will be repeated 1060 * in parentheses. As name resolution in the 1061 * main server loop could stall, and logging 1062 * resolved names adds little or no value to 1063 * incident investigation, this implementation 1064 * only repeats the IP address in parentheses. 1065 * This should resemble librwap's refuse() 1066 * closely enough not to break auditing 1067 * software like sshguard or custom scripts. 1068 */ 1069 syslog(LOG_WARNING, 1070 "refused connect from %s (%s)", 1071 eval_hostaddr(req.client), 1072 eval_hostaddr(req.client)); 1073 debug("Connection refused by tcp wrapper"); 1074 continue; 1075 } 1076 #endif /* LIBWRAP */ 1077 if (unset_nonblock(*newsock) == -1) { 1078 close(*newsock); 1079 continue; 1080 } 1081 if (pipe(startup_p) == -1) { 1082 error_f("pipe(startup_p): %s", strerror(errno)); 1083 close(*newsock); 1084 continue; 1085 } 1086 if (drop_connection(*newsock, 1087 children_active, startup_p[0])) { 1088 close(*newsock); 1089 close(startup_p[0]); 1090 close(startup_p[1]); 1091 continue; 1092 } 1093 1094 if (socketpair(AF_UNIX, 1095 SOCK_STREAM, 0, config_s) == -1) { 1096 error("reexec socketpair: %s", 1097 strerror(errno)); 1098 close(*newsock); 1099 close(startup_p[0]); 1100 close(startup_p[1]); 1101 continue; 1102 } 1103 1104 /* 1105 * Got connection. Fork a child to handle it, unless 1106 * we are in debugging mode. 1107 */ 1108 if (debug_flag) { 1109 /* 1110 * In debugging mode. Close the listening 1111 * socket, and start processing the 1112 * connection without forking. 1113 */ 1114 debug("Server will not fork when running in debugging mode."); 1115 close_listen_socks(); 1116 *sock_in = *newsock; 1117 *sock_out = *newsock; 1118 close(startup_p[0]); 1119 close(startup_p[1]); 1120 startup_pipe = -1; 1121 send_rexec_state(config_s[0], cfg); 1122 close(config_s[0]); 1123 free(pfd); 1124 return; 1125 } 1126 1127 /* 1128 * Normal production daemon. Fork, and have 1129 * the child process the connection. The 1130 * parent continues listening. 1131 */ 1132 platform_pre_fork(); 1133 listening++; 1134 child = child_register(startup_p[0], *newsock); 1135 if ((child->pid = fork()) == 0) { 1136 /* 1137 * Child. Close the listening and 1138 * max_startup sockets. Start using 1139 * the accepted socket. Reinitialize 1140 * logging (since our pid has changed). 1141 * We return from this function to handle 1142 * the connection. 1143 */ 1144 platform_post_fork_child(); 1145 startup_pipe = startup_p[1]; 1146 close_startup_pipes(); 1147 close_listen_socks(); 1148 *sock_in = *newsock; 1149 *sock_out = *newsock; 1150 log_init(__progname, 1151 options.log_level, 1152 options.log_facility, 1153 log_stderr); 1154 close(config_s[0]); 1155 free(pfd); 1156 return; 1157 } 1158 1159 /* Parent. Stay in the loop. */ 1160 platform_post_fork_parent(child->pid); 1161 if (child->pid == -1) 1162 error("fork: %.100s", strerror(errno)); 1163 else 1164 debug("Forked child %ld.", (long)child->pid); 1165 1166 close(startup_p[1]); 1167 1168 close(config_s[1]); 1169 send_rexec_state(config_s[0], cfg); 1170 close(config_s[0]); 1171 close(*newsock); 1172 1173 /* 1174 * Ensure that our random state differs 1175 * from that of the child 1176 */ 1177 arc4random_stir(); 1178 arc4random_buf(rnd, sizeof(rnd)); 1179 #ifdef WITH_OPENSSL 1180 RAND_seed(rnd, sizeof(rnd)); 1181 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1182 fatal("%s: RAND_bytes failed", __func__); 1183 #endif 1184 explicit_bzero(rnd, sizeof(rnd)); 1185 } 1186 } 1187 } 1188 1189 static void 1190 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1191 struct sshkey *key) 1192 { 1193 static struct ssh_digest_ctx *ctx; 1194 u_char *hash; 1195 size_t len; 1196 struct sshbuf *buf; 1197 int r; 1198 1199 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1200 fatal_f("ssh_digest_start"); 1201 if (key == NULL) { /* finalize */ 1202 /* add server config in case we are using agent for host keys */ 1203 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1204 sshbuf_len(server_cfg)) != 0) 1205 fatal_f("ssh_digest_update"); 1206 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1207 hash = xmalloc(len); 1208 if (ssh_digest_final(ctx, hash, len) != 0) 1209 fatal_f("ssh_digest_final"); 1210 options.timing_secret = PEEK_U64(hash); 1211 freezero(hash, len); 1212 ssh_digest_free(ctx); 1213 ctx = NULL; 1214 return; 1215 } 1216 if ((buf = sshbuf_new()) == NULL) 1217 fatal_f("could not allocate buffer"); 1218 if ((r = sshkey_private_serialize(key, buf)) != 0) 1219 fatal_fr(r, "encode %s key", sshkey_ssh_name(key)); 1220 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1221 fatal_f("ssh_digest_update"); 1222 sshbuf_reset(buf); 1223 sshbuf_free(buf); 1224 } 1225 1226 static char * 1227 prepare_proctitle(int ac, char **av) 1228 { 1229 char *ret = NULL; 1230 int i; 1231 1232 for (i = 0; i < ac; i++) 1233 xextendf(&ret, " ", "%s", av[i]); 1234 return ret; 1235 } 1236 1237 static void 1238 print_config(struct connection_info *connection_info) 1239 { 1240 connection_info->test = 1; 1241 parse_server_match_config(&options, &includes, connection_info); 1242 dump_config(&options); 1243 exit(0); 1244 } 1245 1246 /* 1247 * Main program for the daemon. 1248 */ 1249 int 1250 main(int ac, char **av) 1251 { 1252 extern char *optarg; 1253 extern int optind; 1254 int log_stderr = 0, inetd_flag = 0, test_flag = 0, no_daemon_flag = 0; 1255 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 1256 int r, opt, do_dump_cfg = 0, keytype, already_daemon, have_agent = 0; 1257 int sock_in = -1, sock_out = -1, newsock = -1, rexec_argc = 0; 1258 int devnull, config_s[2] = { -1 , -1 }, have_connection_info = 0; 1259 int need_chroot = 1; 1260 char *fp, *line, *logfile = NULL, **rexec_argv = NULL; 1261 struct stat sb; 1262 u_int i, j; 1263 mode_t new_umask; 1264 struct sshkey *key; 1265 struct sshkey *pubkey; 1266 struct connection_info connection_info; 1267 sigset_t sigmask; 1268 1269 memset(&connection_info, 0, sizeof(connection_info)); 1270 #ifdef HAVE_SECUREWARE 1271 (void)set_auth_parameters(ac, av); 1272 #endif 1273 __progname = ssh_get_progname(av[0]); 1274 1275 sigemptyset(&sigmask); 1276 sigprocmask(SIG_SETMASK, &sigmask, NULL); 1277 1278 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1279 saved_argc = ac; 1280 rexec_argc = ac; 1281 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1282 for (i = 0; (int)i < ac; i++) 1283 saved_argv[i] = xstrdup(av[i]); 1284 saved_argv[i] = NULL; 1285 1286 #ifndef HAVE_SETPROCTITLE 1287 /* Prepare for later setproctitle emulation */ 1288 compat_init_setproctitle(ac, av); 1289 av = saved_argv; 1290 #endif 1291 1292 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1293 debug("setgroups(): %.200s", strerror(errno)); 1294 1295 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1296 sanitise_stdfd(); 1297 1298 /* Initialize configuration options to their default values. */ 1299 initialize_server_options(&options); 1300 1301 /* Parse command-line arguments. */ 1302 while ((opt = getopt(ac, av, 1303 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) { 1304 switch (opt) { 1305 case '4': 1306 options.address_family = AF_INET; 1307 break; 1308 case '6': 1309 options.address_family = AF_INET6; 1310 break; 1311 case 'f': 1312 config_file_name = optarg; 1313 break; 1314 case 'c': 1315 servconf_add_hostcert("[command-line]", 0, 1316 &options, optarg); 1317 break; 1318 case 'd': 1319 if (debug_flag == 0) { 1320 debug_flag = 1; 1321 options.log_level = SYSLOG_LEVEL_DEBUG1; 1322 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1323 options.log_level++; 1324 break; 1325 case 'D': 1326 no_daemon_flag = 1; 1327 break; 1328 case 'G': 1329 do_dump_cfg = 1; 1330 break; 1331 case 'E': 1332 logfile = optarg; 1333 /* FALLTHROUGH */ 1334 case 'e': 1335 log_stderr = 1; 1336 break; 1337 case 'i': 1338 inetd_flag = 1; 1339 break; 1340 case 'r': 1341 logit("-r option is deprecated"); 1342 break; 1343 case 'R': 1344 fatal("-R not supported here"); 1345 break; 1346 case 'Q': 1347 /* ignored */ 1348 break; 1349 case 'q': 1350 options.log_level = SYSLOG_LEVEL_QUIET; 1351 break; 1352 case 'b': 1353 /* protocol 1, ignored */ 1354 break; 1355 case 'p': 1356 options.ports_from_cmdline = 1; 1357 if (options.num_ports >= MAX_PORTS) { 1358 fprintf(stderr, "too many ports.\n"); 1359 exit(1); 1360 } 1361 options.ports[options.num_ports++] = a2port(optarg); 1362 if (options.ports[options.num_ports-1] <= 0) { 1363 fprintf(stderr, "Bad port number.\n"); 1364 exit(1); 1365 } 1366 break; 1367 case 'g': 1368 if ((options.login_grace_time = convtime(optarg)) == -1) { 1369 fprintf(stderr, "Invalid login grace time.\n"); 1370 exit(1); 1371 } 1372 break; 1373 case 'k': 1374 /* protocol 1, ignored */ 1375 break; 1376 case 'h': 1377 servconf_add_hostkey("[command-line]", 0, 1378 &options, optarg, 1); 1379 break; 1380 case 't': 1381 test_flag = 1; 1382 break; 1383 case 'T': 1384 test_flag = 2; 1385 break; 1386 case 'C': 1387 if (parse_server_match_testspec(&connection_info, 1388 optarg) == -1) 1389 exit(1); 1390 have_connection_info = 1; 1391 break; 1392 case 'u': 1393 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1394 if (utmp_len > HOST_NAME_MAX+1) { 1395 fprintf(stderr, "Invalid utmp length.\n"); 1396 exit(1); 1397 } 1398 break; 1399 case 'o': 1400 line = xstrdup(optarg); 1401 if (process_server_config_line(&options, line, 1402 "command-line", 0, NULL, NULL, &includes) != 0) 1403 exit(1); 1404 free(line); 1405 break; 1406 case 'V': 1407 fprintf(stderr, "%s, %s\n", 1408 SSH_RELEASE, SSH_OPENSSL_VERSION); 1409 exit(0); 1410 default: 1411 usage(); 1412 break; 1413 } 1414 } 1415 if (!test_flag && !inetd_flag && !do_dump_cfg && !path_absolute(av[0])) 1416 fatal("sshd requires execution with an absolute path"); 1417 1418 closefrom(STDERR_FILENO + 1); 1419 1420 /* Reserve fds we'll need later for reexec things */ 1421 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) 1422 fatal("open %s: %s", _PATH_DEVNULL, strerror(errno)); 1423 while (devnull < REEXEC_MIN_FREE_FD) { 1424 if ((devnull = dup(devnull)) == -1) 1425 fatal("dup %s: %s", _PATH_DEVNULL, strerror(errno)); 1426 } 1427 1428 seed_rng(); 1429 1430 /* If requested, redirect the logs to the specified logfile. */ 1431 if (logfile != NULL) { 1432 char *cp, pid_s[32]; 1433 1434 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid()); 1435 cp = percent_expand(logfile, 1436 "p", pid_s, 1437 "P", "sshd", 1438 (char *)NULL); 1439 log_redirect_stderr_to(cp); 1440 free(cp); 1441 } 1442 1443 /* 1444 * Force logging to stderr until we have loaded the private host 1445 * key (unless started from inetd) 1446 */ 1447 log_init(__progname, 1448 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1449 SYSLOG_LEVEL_INFO : options.log_level, 1450 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1451 SYSLOG_FACILITY_AUTH : options.log_facility, 1452 log_stderr || !inetd_flag || debug_flag); 1453 1454 /* 1455 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1456 * root's environment 1457 */ 1458 if (getenv("KRB5CCNAME") != NULL) 1459 (void) unsetenv("KRB5CCNAME"); 1460 1461 sensitive_data.have_ssh2_key = 0; 1462 1463 /* 1464 * If we're not doing an extended test do not silently ignore connection 1465 * test params. 1466 */ 1467 if (test_flag < 2 && have_connection_info) 1468 fatal("Config test connection parameter (-C) provided without " 1469 "test mode (-T)"); 1470 1471 /* Fetch our configuration */ 1472 if ((cfg = sshbuf_new()) == NULL) 1473 fatal("sshbuf_new config failed"); 1474 if (strcasecmp(config_file_name, "none") != 0) 1475 load_server_config(config_file_name, cfg); 1476 1477 parse_server_config(&options, config_file_name, cfg, 1478 &includes, NULL, 0); 1479 1480 /* Fill in default values for those options not explicitly set. */ 1481 fill_default_server_options(&options); 1482 1483 /* Check that options are sensible */ 1484 if (options.authorized_keys_command_user == NULL && 1485 (options.authorized_keys_command != NULL && 1486 strcasecmp(options.authorized_keys_command, "none") != 0)) 1487 fatal("AuthorizedKeysCommand set without " 1488 "AuthorizedKeysCommandUser"); 1489 if (options.authorized_principals_command_user == NULL && 1490 (options.authorized_principals_command != NULL && 1491 strcasecmp(options.authorized_principals_command, "none") != 0)) 1492 fatal("AuthorizedPrincipalsCommand set without " 1493 "AuthorizedPrincipalsCommandUser"); 1494 1495 /* 1496 * Check whether there is any path through configured auth methods. 1497 * Unfortunately it is not possible to verify this generally before 1498 * daemonisation in the presence of Match blocks, but this catches 1499 * and warns for trivial misconfigurations that could break login. 1500 */ 1501 if (options.num_auth_methods != 0) { 1502 for (i = 0; i < options.num_auth_methods; i++) { 1503 if (auth2_methods_valid(options.auth_methods[i], 1504 1) == 0) 1505 break; 1506 } 1507 if (i >= options.num_auth_methods) 1508 fatal("AuthenticationMethods cannot be satisfied by " 1509 "enabled authentication methods"); 1510 } 1511 1512 /* Check that there are no remaining arguments. */ 1513 if (optind < ac) { 1514 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1515 exit(1); 1516 } 1517 1518 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1519 1520 if (do_dump_cfg) 1521 print_config(&connection_info); 1522 1523 /* load host keys */ 1524 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1525 sizeof(struct sshkey *)); 1526 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1527 sizeof(struct sshkey *)); 1528 1529 if (options.host_key_agent) { 1530 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1531 setenv(SSH_AUTHSOCKET_ENV_NAME, 1532 options.host_key_agent, 1); 1533 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1534 have_agent = 1; 1535 else 1536 error_r(r, "Could not connect to agent \"%s\"", 1537 options.host_key_agent); 1538 } 1539 1540 for (i = 0; i < options.num_host_key_files; i++) { 1541 int ll = options.host_key_file_userprovided[i] ? 1542 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1543 1544 if (options.host_key_files[i] == NULL) 1545 continue; 1546 if ((r = sshkey_load_private(options.host_key_files[i], "", 1547 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1548 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1549 options.host_key_files[i]); 1550 if (sshkey_is_sk(key) && 1551 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1552 debug("host key %s requires user presence, ignoring", 1553 options.host_key_files[i]); 1554 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1555 } 1556 if (r == 0 && key != NULL && 1557 (r = sshkey_shield_private(key)) != 0) { 1558 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1559 options.host_key_files[i]); 1560 sshkey_free(key); 1561 key = NULL; 1562 } 1563 if ((r = sshkey_load_public(options.host_key_files[i], 1564 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1565 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1566 options.host_key_files[i]); 1567 if (pubkey != NULL && key != NULL) { 1568 if (!sshkey_equal(pubkey, key)) { 1569 error("Public key for %s does not match " 1570 "private key", options.host_key_files[i]); 1571 sshkey_free(pubkey); 1572 pubkey = NULL; 1573 } 1574 } 1575 if (pubkey == NULL && key != NULL) { 1576 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1577 fatal_r(r, "Could not demote key: \"%s\"", 1578 options.host_key_files[i]); 1579 } 1580 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1581 options.required_rsa_size)) != 0) { 1582 error_fr(r, "Host key %s", options.host_key_files[i]); 1583 sshkey_free(pubkey); 1584 sshkey_free(key); 1585 continue; 1586 } 1587 sensitive_data.host_keys[i] = key; 1588 sensitive_data.host_pubkeys[i] = pubkey; 1589 1590 if (key == NULL && pubkey != NULL && have_agent) { 1591 debug("will rely on agent for hostkey %s", 1592 options.host_key_files[i]); 1593 keytype = pubkey->type; 1594 } else if (key != NULL) { 1595 keytype = key->type; 1596 accumulate_host_timing_secret(cfg, key); 1597 } else { 1598 do_log2(ll, "Unable to load host key: %s", 1599 options.host_key_files[i]); 1600 sensitive_data.host_keys[i] = NULL; 1601 sensitive_data.host_pubkeys[i] = NULL; 1602 continue; 1603 } 1604 1605 switch (keytype) { 1606 case KEY_RSA: 1607 case KEY_DSA: 1608 case KEY_ECDSA: 1609 case KEY_ED25519: 1610 case KEY_ECDSA_SK: 1611 case KEY_ED25519_SK: 1612 case KEY_XMSS: 1613 if (have_agent || key != NULL) 1614 sensitive_data.have_ssh2_key = 1; 1615 break; 1616 } 1617 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1618 SSH_FP_DEFAULT)) == NULL) 1619 fatal("sshkey_fingerprint failed"); 1620 debug("%s host key #%d: %s %s", 1621 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1622 free(fp); 1623 } 1624 accumulate_host_timing_secret(cfg, NULL); 1625 if (!sensitive_data.have_ssh2_key) { 1626 logit("sshd: no hostkeys available -- exiting."); 1627 exit(1); 1628 } 1629 1630 /* 1631 * Load certificates. They are stored in an array at identical 1632 * indices to the public keys that they relate to. 1633 */ 1634 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1635 sizeof(struct sshkey *)); 1636 for (i = 0; i < options.num_host_key_files; i++) 1637 sensitive_data.host_certificates[i] = NULL; 1638 1639 for (i = 0; i < options.num_host_cert_files; i++) { 1640 if (options.host_cert_files[i] == NULL) 1641 continue; 1642 if ((r = sshkey_load_public(options.host_cert_files[i], 1643 &key, NULL)) != 0) { 1644 error_r(r, "Could not load host certificate \"%s\"", 1645 options.host_cert_files[i]); 1646 continue; 1647 } 1648 if (!sshkey_is_cert(key)) { 1649 error("Certificate file is not a certificate: %s", 1650 options.host_cert_files[i]); 1651 sshkey_free(key); 1652 continue; 1653 } 1654 /* Find matching private key */ 1655 for (j = 0; j < options.num_host_key_files; j++) { 1656 if (sshkey_equal_public(key, 1657 sensitive_data.host_pubkeys[j])) { 1658 sensitive_data.host_certificates[j] = key; 1659 break; 1660 } 1661 } 1662 if (j >= options.num_host_key_files) { 1663 error("No matching private key for certificate: %s", 1664 options.host_cert_files[i]); 1665 sshkey_free(key); 1666 continue; 1667 } 1668 sensitive_data.host_certificates[j] = key; 1669 debug("host certificate: #%u type %d %s", j, key->type, 1670 sshkey_type(key)); 1671 } 1672 1673 /* Ensure privsep directory is correctly configured. */ 1674 need_chroot = ((getuid() == 0 || geteuid() == 0) || 1675 options.kerberos_authentication); 1676 if ((getpwnam(SSH_PRIVSEP_USER)) == NULL && need_chroot) { 1677 fatal("Privilege separation user %s does not exist", 1678 SSH_PRIVSEP_USER); 1679 } 1680 endpwent(); 1681 1682 if (need_chroot) { 1683 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &sb) == -1) || 1684 (S_ISDIR(sb.st_mode) == 0)) 1685 fatal("Missing privilege separation directory: %s", 1686 _PATH_PRIVSEP_CHROOT_DIR); 1687 #ifdef HAVE_CYGWIN 1688 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1689 (sb.st_uid != getuid () || 1690 (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1691 #else 1692 if (sb.st_uid != 0 || (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1693 #endif 1694 fatal("%s must be owned by root and not group or " 1695 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1696 } 1697 1698 if (test_flag > 1) 1699 print_config(&connection_info); 1700 1701 /* Configuration looks good, so exit if in test mode. */ 1702 if (test_flag) 1703 exit(0); 1704 1705 /* 1706 * Clear out any supplemental groups we may have inherited. This 1707 * prevents inadvertent creation of files with bad modes (in the 1708 * portable version at least, it's certainly possible for PAM 1709 * to create a file, and we can't control the code in every 1710 * module which might be used). 1711 */ 1712 if (setgroups(0, NULL) < 0) 1713 debug("setgroups() failed: %.200s", strerror(errno)); 1714 1715 /* Prepare arguments for sshd-session */ 1716 if (rexec_argc < 0) 1717 fatal("rexec_argc %d < 0", rexec_argc); 1718 rexec_argv = xcalloc(rexec_argc + 3, sizeof(char *)); 1719 /* Point to the sshd-session binary instead of sshd */ 1720 rexec_argv[0] = options.sshd_session_path; 1721 for (i = 1; i < (u_int)rexec_argc; i++) { 1722 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1723 rexec_argv[i] = saved_argv[i]; 1724 } 1725 rexec_argv[rexec_argc++] = "-R"; 1726 rexec_argv[rexec_argc] = NULL; 1727 if (stat(rexec_argv[0], &sb) != 0 || !(sb.st_mode & (S_IXOTH|S_IXUSR))) 1728 fatal("%s does not exist or is not executable", rexec_argv[0]); 1729 debug3("using %s for re-exec", rexec_argv[0]); 1730 1731 listener_proctitle = prepare_proctitle(ac, av); 1732 1733 /* Ensure that umask disallows at least group and world write */ 1734 new_umask = umask(0077) | 0022; 1735 (void) umask(new_umask); 1736 1737 /* Initialize the log (it is reinitialized below in case we forked). */ 1738 if (debug_flag && !inetd_flag) 1739 log_stderr = 1; 1740 log_init(__progname, options.log_level, 1741 options.log_facility, log_stderr); 1742 for (i = 0; i < options.num_log_verbose; i++) 1743 log_verbose_add(options.log_verbose[i]); 1744 1745 /* 1746 * If not in debugging mode, not started from inetd and not already 1747 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1748 * terminal, and fork. The original process exits. 1749 */ 1750 already_daemon = daemonized(); 1751 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1752 1753 if (daemon(0, 0) == -1) 1754 fatal("daemon() failed: %.200s", strerror(errno)); 1755 1756 disconnect_controlling_tty(); 1757 } 1758 /* Reinitialize the log (because of the fork above). */ 1759 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1760 1761 /* Avoid killing the process in high-pressure swapping environments. */ 1762 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1763 debug("madvise(): %.200s", strerror(errno)); 1764 1765 /* 1766 * Chdir to the root directory so that the current disk can be 1767 * unmounted if desired. 1768 */ 1769 if (chdir("/") == -1) 1770 error("chdir(\"/\"): %s", strerror(errno)); 1771 1772 /* ignore SIGPIPE */ 1773 ssh_signal(SIGPIPE, SIG_IGN); 1774 1775 /* Get a connection, either from inetd or a listening TCP socket */ 1776 if (inetd_flag) { 1777 /* Send configuration to ancestor sshd-session process */ 1778 if (socketpair(AF_UNIX, SOCK_STREAM, 0, config_s) == -1) 1779 fatal("socketpair: %s", strerror(errno)); 1780 send_rexec_state(config_s[0], cfg); 1781 close(config_s[0]); 1782 } else { 1783 platform_pre_listen(); 1784 server_listen(); 1785 1786 ssh_signal(SIGHUP, sighup_handler); 1787 ssh_signal(SIGCHLD, main_sigchld_handler); 1788 ssh_signal(SIGTERM, sigterm_handler); 1789 ssh_signal(SIGQUIT, sigterm_handler); 1790 #ifdef SIGINFO 1791 ssh_signal(SIGINFO, siginfo_handler); 1792 #endif 1793 1794 platform_post_listen(); 1795 1796 /* 1797 * Write out the pid file after the sigterm handler 1798 * is setup and the listen sockets are bound 1799 */ 1800 if (options.pid_file != NULL && !debug_flag) { 1801 FILE *f = fopen(options.pid_file, "w"); 1802 1803 if (f == NULL) { 1804 error("Couldn't create pid file \"%s\": %s", 1805 options.pid_file, strerror(errno)); 1806 } else { 1807 fprintf(f, "%ld\n", (long) getpid()); 1808 fclose(f); 1809 } 1810 } 1811 1812 /* Accept a connection and return in a forked child */ 1813 server_accept_loop(&sock_in, &sock_out, 1814 &newsock, config_s, log_stderr); 1815 } 1816 1817 /* This is the child processing a new connection. */ 1818 setproctitle("%s", "[accepted]"); 1819 1820 /* 1821 * Create a new session and process group since the 4.4BSD 1822 * setlogin() affects the entire process group. We don't 1823 * want the child to be able to affect the parent. 1824 */ 1825 if (!debug_flag && !inetd_flag && setsid() == -1) 1826 error("setsid: %.100s", strerror(errno)); 1827 1828 debug("rexec start in %d out %d newsock %d pipe %d sock %d/%d", 1829 sock_in, sock_out, newsock, startup_pipe, config_s[0], config_s[1]); 1830 if (!inetd_flag) { 1831 if (dup2(newsock, STDIN_FILENO) == -1) 1832 fatal("dup2 stdin: %s", strerror(errno)); 1833 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1) 1834 fatal("dup2 stdout: %s", strerror(errno)); 1835 if (newsock > STDOUT_FILENO) 1836 close(newsock); 1837 } 1838 if (config_s[1] != REEXEC_CONFIG_PASS_FD) { 1839 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1) 1840 fatal("dup2 config_s: %s", strerror(errno)); 1841 close(config_s[1]); 1842 } 1843 if (startup_pipe == -1) 1844 close(REEXEC_STARTUP_PIPE_FD); 1845 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1846 if (dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD) == -1) 1847 fatal("dup2 startup_p: %s", strerror(errno)); 1848 close(startup_pipe); 1849 } 1850 log_redirect_stderr_to(NULL); 1851 closefrom(REEXEC_MIN_FREE_FD); 1852 1853 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1854 execv(rexec_argv[0], rexec_argv); 1855 1856 fatal("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1857 #ifdef __FreeBSD__ 1858 /* 1859 * Initialize the resolver. This may not happen automatically 1860 * before privsep chroot(). 1861 */ 1862 if ((_res.options & RES_INIT) == 0) { 1863 debug("res_init()"); 1864 res_init(); 1865 } 1866 #ifdef GSSAPI 1867 /* 1868 * Force GSS-API to parse its configuration and load any 1869 * mechanism plugins. 1870 */ 1871 { 1872 gss_OID_set mechs; 1873 OM_uint32 minor_status; 1874 gss_indicate_mechs(&minor_status, &mechs); 1875 gss_release_oid_set(&minor_status, &mechs); 1876 } 1877 #endif 1878 #endif 1879 1880 1881 BLACKLIST_INIT(); 1882 } 1883 1884 /* server specific fatal cleanup */ 1885 void 1886 cleanup_exit(int i) 1887 { 1888 _exit(i); 1889 } 1890