1 /* $OpenBSD: sshd.c,v 1.628 2026/06/29 07:36:37 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 #include <sys/stat.h> 34 #include <sys/time.h> 35 #include <sys/queue.h> 36 #include <sys/wait.h> 37 #include <sys/utsname.h> 38 39 #include <errno.h> 40 #include <fcntl.h> 41 #include <netdb.h> 42 #include <paths.h> 43 #include <grp.h> 44 #include <poll.h> 45 #include <pwd.h> 46 #include <signal.h> 47 #include <stdarg.h> 48 #include <time.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <limits.h> 54 55 #ifdef HAVE_SECUREWARE 56 #include <sys/security.h> 57 #include <prot.h> 58 #endif 59 60 #ifdef __FreeBSD__ 61 #include <resolv.h> 62 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 63 #include <gssapi/gssapi.h> 64 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 65 #include <gssapi.h> 66 #endif 67 #endif 68 69 #include "xmalloc.h" 70 #include "ssh.h" 71 #include "sshpty.h" 72 #include "log.h" 73 #include "sshbuf.h" 74 #include "misc.h" 75 #include "servconf.h" 76 #include "compat.h" 77 #include "digest.h" 78 #include "sshkey.h" 79 #include "authfile.h" 80 #include "pathnames.h" 81 #include "canohost.h" 82 #include "hostfile.h" 83 #include "auth.h" 84 #include "authfd.h" 85 #include "msg.h" 86 #include "version.h" 87 #include "ssherr.h" 88 #include "sk-api.h" 89 #include "addr.h" 90 #include "srclimit.h" 91 #include "atomicio.h" 92 #ifdef GSSAPI 93 #include "ssh-gss.h" 94 #endif 95 #include "monitor_wrap.h" 96 97 #ifdef LIBWRAP 98 #include <tcpd.h> 99 #include <syslog.h> 100 #endif /* LIBWRAP */ 101 102 /* Re-exec fds */ 103 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 104 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 2) 105 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 3) 106 107 extern char *__progname; 108 109 /* Server configuration options. */ 110 ServerOptions options; 111 112 /* 113 * Debug mode flag. This can be set on the command line. If debug 114 * mode is enabled, extra debugging output will be sent to the system 115 * log, the daemon will not go to background, and will exit after processing 116 * the first connection. 117 */ 118 int debug_flag = 0; 119 120 /* Saved arguments to main(). */ 121 static char **saved_argv; 122 static int saved_argc; 123 124 /* 125 * The sockets that the server is listening; this is used in the SIGHUP 126 * signal handler. 127 */ 128 #define MAX_LISTEN_SOCKS 16 129 static int listen_socks[MAX_LISTEN_SOCKS]; 130 static int num_listen_socks = 0; 131 132 /* 133 * Any really sensitive data in the application is contained in this 134 * structure. The idea is that this structure could be locked into memory so 135 * that the pages do not get written into swap. However, there are some 136 * problems. The private key contains BIGNUMs, and we do not (in principle) 137 * have access to the internals of them, and locking just the structure is 138 * not very useful. Currently, memory locking is not implemented. 139 */ 140 struct { 141 struct sshkey **host_keys; /* all private host keys */ 142 struct sshkey **host_pubkeys; /* all public host keys */ 143 struct sshkey **host_certificates; /* all public host certificates */ 144 int have_ssh2_key; 145 } sensitive_data; 146 147 /* This is set to true when a signal is received. */ 148 static volatile sig_atomic_t received_siginfo = 0; 149 static volatile sig_atomic_t received_sigchld = 0; 150 static volatile sig_atomic_t received_sighup = 0; 151 static volatile sig_atomic_t received_sigterm = 0; 152 153 /* record remote hostname or ip */ 154 u_int utmp_len = HOST_NAME_MAX+1; 155 156 /* 157 * The early_child/children array below is used for tracking children of the 158 * listening sshd process early in their lifespans, before they have 159 * completed authentication. This tracking is needed for four things: 160 * 161 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 162 * connections. 163 * 2) Avoiding a race condition for SIGHUP processing, where child processes 164 * may have listen_socks open that could collide with main listener process 165 * after it restarts. 166 * 3) Ensuring that rexec'd sshd processes have received their initial state 167 * from the parent listen process before handling SIGHUP. 168 * 4) Tracking and logging unsuccessful exits from the preauth sshd monitor, 169 * including and especially those for LoginGraceTime timeouts. 170 * 171 * Child processes signal that they have completed closure of the listen_socks 172 * and (if applicable) received their rexec state by sending a char over their 173 * sock. 174 * 175 * Child processes signal that authentication has completed by sending a 176 * second char over the socket before closing it, otherwise the listener will 177 * continue tracking the child (and using up a MaxStartups slot) until the 178 * preauth subprocess exits, whereupon the listener will log its exit status. 179 * preauth processes will exit with a status of EXIT_LOGIN_GRACE to indicate 180 * they did not authenticate before the LoginGraceTime alarm fired. 181 */ 182 struct early_child { 183 int pipefd; 184 int early; /* Indicates child closed listener */ 185 char *id; /* human readable connection identifier */ 186 pid_t pid; 187 struct xaddr addr; 188 int have_addr; 189 int status, have_status; 190 struct sshbuf *config; 191 struct sshbuf *keys; 192 }; 193 static struct early_child *children; 194 static int children_active; 195 196 /* sshd_config buffer */ 197 struct sshbuf *cfg; 198 struct sshbuf *config; /* packed */ 199 200 /* Included files from the configuration file */ 201 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 202 203 /* message to be displayed after login */ 204 struct sshbuf *loginmsg; 205 206 /* Unprivileged user */ 207 struct passwd *privsep_pw = NULL; 208 209 static char *listener_proctitle; 210 211 /* 212 * Close all listening sockets 213 */ 214 static void 215 close_listen_socks(void) 216 { 217 int i; 218 219 for (i = 0; i < num_listen_socks; i++) 220 close(listen_socks[i]); 221 num_listen_socks = 0; 222 } 223 224 /* Allocate and initialise the children array */ 225 static void 226 child_alloc(void) 227 { 228 int i; 229 230 children = xcalloc(options.max_startups, sizeof(*children)); 231 for (i = 0; i < options.max_startups; i++) { 232 children[i].pipefd = -1; 233 children[i].pid = -1; 234 } 235 } 236 237 /* Register a new connection in the children array; child pid comes later */ 238 static struct early_child * 239 child_register(int pipefd, int sockfd) 240 { 241 int i, lport, rport; 242 char *laddr = NULL, *raddr = NULL; 243 struct early_child *child = NULL; 244 struct sockaddr_storage addr; 245 socklen_t addrlen = sizeof(addr); 246 struct sockaddr *sa = (struct sockaddr *)&addr; 247 248 for (i = 0; i < options.max_startups; i++) { 249 if (children[i].pipefd != -1 || 250 children[i].config != NULL || 251 children[i].keys != NULL || 252 children[i].pid > 0) 253 continue; 254 child = &(children[i]); 255 break; 256 } 257 if (child == NULL) { 258 fatal_f("error: accepted connection when all %d child " 259 " slots full", options.max_startups); 260 } 261 child->pipefd = pipefd; 262 child->early = 1; 263 if ((child->config = sshbuf_fromb(config)) == NULL) 264 fatal_f("sshbuf_fromb failed"); 265 /* record peer address, if available */ 266 if (getpeername(sockfd, sa, &addrlen) == 0 && 267 addr_sa_to_xaddr(sa, addrlen, &child->addr) == 0) 268 child->have_addr = 1; 269 /* format peer address string for logs */ 270 if ((lport = get_local_port(sockfd)) == 0 || 271 (rport = get_peer_port(sockfd)) == 0) { 272 /* Not a TCP socket */ 273 raddr = get_peer_ipaddr(sockfd); 274 xasprintf(&child->id, "connection from %s", raddr); 275 } else { 276 laddr = get_local_ipaddr(sockfd); 277 raddr = get_peer_ipaddr(sockfd); 278 xasprintf(&child->id, "connection from %s to %s", raddr, laddr); 279 } 280 free(laddr); 281 free(raddr); 282 if (++children_active > options.max_startups) 283 fatal_f("internal error: more children than max_startups"); 284 285 return child; 286 } 287 288 /* 289 * Finally free a child entry. Don't call this directly. 290 */ 291 static void 292 child_finish(struct early_child *child) 293 { 294 if (children_active == 0) 295 fatal_f("internal error: children_active underflow"); 296 if (child->pipefd != -1) { 297 srclimit_done(child->pipefd); 298 close(child->pipefd); 299 } 300 sshbuf_free(child->config); 301 sshbuf_free(child->keys); 302 free(child->id); 303 memset(child, '\0', sizeof(*child)); 304 child->pipefd = -1; 305 child->pid = -1; 306 children_active--; 307 } 308 309 /* 310 * Close a child's pipe. This will not stop tracking the child immediately 311 * (it will still be tracked for waitpid()) unless force_final is set, or 312 * child has already exited. 313 */ 314 static void 315 child_close(struct early_child *child, int force_final, int quiet) 316 { 317 if (!quiet) 318 debug_f("enter%s", force_final ? " (forcing)" : ""); 319 if (child->pipefd != -1) { 320 srclimit_done(child->pipefd); 321 close(child->pipefd); 322 child->pipefd = -1; 323 } 324 if (child->pid == -1 || force_final) 325 child_finish(child); 326 } 327 328 /* Record a child exit. Safe to call from signal handlers */ 329 static void 330 child_exit(pid_t pid, int status) 331 { 332 int i; 333 334 if (children == NULL || pid <= 0) 335 return; 336 for (i = 0; i < options.max_startups; i++) { 337 if (children[i].pid == pid) { 338 children[i].have_status = 1; 339 children[i].status = status; 340 break; 341 } 342 } 343 } 344 345 /* 346 * Reap a child entry that has exited, as previously flagged 347 * using child_exit(). 348 * Handles logging of exit condition and will finalise the child if its pipe 349 * had already been closed. 350 */ 351 static void 352 child_reap(struct early_child *child) 353 { 354 LogLevel level = SYSLOG_LEVEL_DEBUG1; 355 int was_crash, penalty_type = SRCLIMIT_PENALTY_NONE; 356 const char *child_status; 357 358 if (child->config) 359 child_status = " (sending config)"; 360 else if (child->keys) 361 child_status = " (sending keys)"; 362 else if (child->early) 363 child_status = " (early)"; 364 else 365 child_status = ""; 366 367 /* Log exit information */ 368 if (WIFSIGNALED(child->status)) { 369 /* 370 * Increase logging for signals potentially associated 371 * with serious conditions. 372 */ 373 if ((was_crash = signal_is_crash(WTERMSIG(child->status)))) 374 level = SYSLOG_LEVEL_ERROR; 375 do_log2(level, "session process %ld for %s killed by " 376 "signal %d%s", (long)child->pid, child->id, 377 WTERMSIG(child->status), child_status); 378 if (was_crash) 379 penalty_type = SRCLIMIT_PENALTY_CRASH; 380 } else if (!WIFEXITED(child->status)) { 381 penalty_type = SRCLIMIT_PENALTY_CRASH; 382 error("session process %ld for %s terminated abnormally, " 383 "status=0x%x%s", (long)child->pid, child->id, child->status, 384 child_status); 385 } else { 386 /* Normal exit. We care about the status */ 387 switch (WEXITSTATUS(child->status)) { 388 case 0: 389 debug3_f("preauth child %ld for %s completed " 390 "normally%s", (long)child->pid, child->id, 391 child_status); 392 break; 393 case EXIT_LOGIN_GRACE: 394 penalty_type = SRCLIMIT_PENALTY_GRACE_EXCEEDED; 395 logit("Timeout before authentication for %s, " 396 "pid = %ld%s", child->id, (long)child->pid, 397 child_status); 398 break; 399 case EXIT_CHILD_CRASH: 400 penalty_type = SRCLIMIT_PENALTY_CRASH; 401 logit("Session process %ld unpriv child crash for %s%s", 402 (long)child->pid, child->id, child_status); 403 break; 404 case EXIT_AUTH_ATTEMPTED: 405 penalty_type = SRCLIMIT_PENALTY_AUTHFAIL; 406 debug_f("preauth child %ld for %s exited " 407 "after unsuccessful auth attempt%s", 408 (long)child->pid, child->id, child_status); 409 break; 410 case EXIT_INVALID_USER: 411 penalty_type = SRCLIMIT_PENALTY_INVALIDUSER; 412 debug_f("preauth child %ld for %s exited " 413 "after auth attempt by invalid user%s", 414 (long)child->pid, child->id, child_status); 415 break; 416 case EXIT_CONFIG_REFUSED: 417 penalty_type = SRCLIMIT_PENALTY_REFUSECONNECTION; 418 debug_f("preauth child %ld for %s prohibited by" 419 "RefuseConnection%s", 420 (long)child->pid, child->id, child_status); 421 break; 422 default: 423 penalty_type = SRCLIMIT_PENALTY_NOAUTH; 424 debug_f("preauth child %ld for %s exited " 425 "with status %d%s", (long)child->pid, child->id, 426 WEXITSTATUS(child->status), child_status); 427 break; 428 } 429 } 430 431 if (child->have_addr) 432 srclimit_penalise(&child->addr, penalty_type); 433 434 child->pid = -1; 435 child->have_status = 0; 436 if (child->pipefd == -1) 437 child_finish(child); 438 } 439 440 /* Reap all children that have exited; called after SIGCHLD */ 441 static void 442 child_reap_all_exited(void) 443 { 444 int i; 445 pid_t pid; 446 int status; 447 448 if (children == NULL) 449 return; 450 451 for (;;) { 452 if ((pid = waitpid(-1, &status, WNOHANG)) == 0) 453 break; 454 else if (pid == -1) { 455 if (errno == EINTR || errno == EAGAIN) 456 continue; 457 if (errno != ECHILD) 458 error_f("waitpid: %s", strerror(errno)); 459 break; 460 } 461 child_exit(pid, status); 462 } 463 464 for (i = 0; i < options.max_startups; i++) { 465 if (!children[i].have_status) 466 continue; 467 child_reap(&(children[i])); 468 } 469 } 470 471 static void 472 close_startup_pipes(void) 473 { 474 int i; 475 476 if (children == NULL) 477 return; 478 for (i = 0; i < options.max_startups; i++) { 479 if (children[i].pipefd != -1) 480 child_close(&(children[i]), 1, 1); 481 } 482 } 483 484 /* Called after SIGINFO */ 485 static void 486 show_info(void) 487 { 488 int i; 489 const char *child_status; 490 491 /* XXX print listening sockets here too */ 492 if (children == NULL) 493 return; 494 logit("%d active startups", children_active); 495 for (i = 0; i < options.max_startups; i++) { 496 if (children[i].pipefd == -1 && children[i].pid <= 0) 497 continue; 498 if (children[i].config) 499 child_status = " (sending config)"; 500 else if (children[i].keys) 501 child_status = " (sending keys)"; 502 else if (children[i].early) 503 child_status = " (early)"; 504 else 505 child_status = ""; 506 logit("child %d: fd=%d pid=%ld %s%s", i, children[i].pipefd, 507 (long)children[i].pid, children[i].id, child_status); 508 } 509 srclimit_penalty_info(); 510 } 511 512 /* 513 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 514 * the effect is to reread the configuration file (and to regenerate 515 * the server key). 516 */ 517 518 static void 519 sighup_handler(int sig) 520 { 521 received_sighup = 1; 522 } 523 524 /* 525 * Called from the main program after receiving SIGHUP. 526 * Restarts the server. 527 */ 528 static void 529 sighup_restart(void) 530 { 531 logit("Received SIGHUP; restarting."); 532 if (options.pid_file != NULL) 533 unlink(options.pid_file); 534 platform_pre_restart(); 535 close_listen_socks(); 536 close_startup_pipes(); 537 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 538 execv(saved_argv[0], saved_argv); 539 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 540 strerror(errno)); 541 exit(1); 542 } 543 544 /* 545 * Generic signal handler for terminating signals in the master daemon. 546 */ 547 static void 548 sigterm_handler(int sig) 549 { 550 received_sigterm = sig; 551 } 552 553 #ifdef SIGINFO 554 static void 555 siginfo_handler(int sig) 556 { 557 received_siginfo = 1; 558 } 559 #endif 560 561 static void 562 main_sigchld_handler(int sig) 563 { 564 received_sigchld = 1; 565 } 566 567 /* 568 * returns 1 if connection should be dropped, 0 otherwise. 569 * dropping starts at connection #max_startups_begin with a probability 570 * of (max_startups_rate/100). the probability increases linearly until 571 * all connections are dropped for startups > max_startups 572 */ 573 static int 574 should_drop_connection(int startups) 575 { 576 int p, r; 577 578 if (startups < options.max_startups_begin) 579 return 0; 580 if (startups >= options.max_startups) 581 return 1; 582 if (options.max_startups_rate == 100) 583 return 1; 584 585 p = 100 - options.max_startups_rate; 586 p *= startups - options.max_startups_begin; 587 p /= options.max_startups - options.max_startups_begin; 588 p += options.max_startups_rate; 589 r = arc4random_uniform(100); 590 591 debug_f("p %d, r %d", p, r); 592 return (r < p) ? 1 : 0; 593 } 594 595 /* 596 * Check whether connection should be accepted by MaxStartups or for penalty. 597 * Returns 0 if the connection is accepted. If the connection is refused, 598 * returns 1 and attempts to send notification to client. 599 * Logs when the MaxStartups condition is entered or exited, and periodically 600 * while in that state. 601 */ 602 static int 603 drop_connection(int sock, int startups, int notify_pipe) 604 { 605 static struct log_ratelimit_ctx ratelimit_maxstartups; 606 static struct log_ratelimit_ctx ratelimit_penalty; 607 static int init_done; 608 char *laddr, *raddr; 609 const char *reason = NULL, *subreason = NULL; 610 const char msg[] = "Not allowed at this time\r\n"; 611 struct log_ratelimit_ctx *rl = NULL; 612 int ratelimited; 613 u_int ndropped; 614 615 if (!init_done) { 616 init_done = 1; 617 log_ratelimit_init(&ratelimit_maxstartups, 4, 60, 20, 5*60); 618 log_ratelimit_init(&ratelimit_penalty, 8, 60, 30, 2*60); 619 } 620 621 /* PerSourcePenalties */ 622 if (!srclimit_penalty_check_allow(sock, &subreason)) { 623 reason = "PerSourcePenalties"; 624 rl = &ratelimit_penalty; 625 } else { 626 /* MaxStartups */ 627 if (!should_drop_connection(startups) && 628 srclimit_check_allow(sock, notify_pipe) == 1) 629 return 0; 630 reason = "Maxstartups"; 631 rl = &ratelimit_maxstartups; 632 } 633 634 laddr = get_local_ipaddr(sock); 635 raddr = get_peer_ipaddr(sock); 636 ratelimited = log_ratelimit(rl, time(NULL), NULL, &ndropped); 637 do_log2(ratelimited ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 638 "drop connection #%d from [%s]:%d on [%s]:%d %s", 639 startups, 640 raddr, get_peer_port(sock), 641 laddr, get_local_port(sock), 642 subreason != NULL ? subreason : reason); 643 free(laddr); 644 free(raddr); 645 if (ndropped != 0) { 646 logit("%s logging rate-limited: additional %u connections " 647 "dropped", reason, ndropped); 648 } 649 650 /* best-effort notification to client */ 651 (void)write(sock, msg, sizeof(msg) - 1); 652 return 1; 653 } 654 655 static void 656 usage(void) 657 { 658 if (options.version_addendum != NULL && 659 *options.version_addendum != '\0') 660 fprintf(stderr, "%s %s, %s\n", 661 SSH_RELEASE, 662 options.version_addendum, SSH_OPENSSL_VERSION); 663 else 664 fprintf(stderr, "%s, %s\n", 665 SSH_RELEASE, SSH_OPENSSL_VERSION); 666 fprintf(stderr, 667 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n" 668 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 669 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 670 ); 671 exit(1); 672 } 673 674 static struct sshbuf * 675 pack_hostkeys(void) 676 { 677 struct sshbuf *m = NULL, *keybuf = NULL, *hostkeys = NULL; 678 int r; 679 u_int i; 680 size_t len; 681 682 if ((m = sshbuf_new()) == NULL || 683 (keybuf = sshbuf_new()) == NULL || 684 (hostkeys = sshbuf_new()) == NULL) 685 fatal_f("sshbuf_new failed"); 686 687 /* pack hostkeys into a string. Empty key slots get empty strings */ 688 for (i = 0; i < options.num_host_key_files; i++) { 689 /* private key */ 690 sshbuf_reset(keybuf); 691 if (sensitive_data.host_keys[i] != NULL && 692 (r = sshkey_private_serialize(sensitive_data.host_keys[i], 693 keybuf)) != 0) 694 fatal_fr(r, "serialize hostkey private"); 695 if ((r = sshbuf_put_stringb(hostkeys, keybuf)) != 0) 696 fatal_fr(r, "compose hostkey private"); 697 /* public key */ 698 if (sensitive_data.host_pubkeys[i] != NULL) { 699 if ((r = sshkey_puts(sensitive_data.host_pubkeys[i], 700 hostkeys)) != 0) 701 fatal_fr(r, "compose hostkey public"); 702 } else { 703 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 704 fatal_fr(r, "compose hostkey empty public"); 705 } 706 /* cert */ 707 if (sensitive_data.host_certificates[i] != NULL) { 708 if ((r = sshkey_puts( 709 sensitive_data.host_certificates[i], 710 hostkeys)) != 0) 711 fatal_fr(r, "compose host cert"); 712 } else { 713 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 714 fatal_fr(r, "compose host cert empty"); 715 } 716 } 717 718 if ((r = sshbuf_put_u32(m, 0)) != 0 || 719 (r = sshbuf_put_u8(m, 0)) != 0 || 720 (r = sshbuf_put_stringb(m, hostkeys)) != 0) 721 fatal_fr(r, "compose message"); 722 if ((len = sshbuf_len(m)) < 5 || len > 0xffffffff) 723 fatal_f("bad length %zu", len); 724 POKE_U32(sshbuf_mutable_ptr(m), len - 4); 725 726 sshbuf_free(keybuf); 727 sshbuf_free(hostkeys); 728 return m; 729 } 730 731 static struct sshbuf * 732 pack_config(struct sshbuf *conf) 733 { 734 struct sshbuf *m = NULL, *inc = NULL; 735 struct include_item *item = NULL; 736 size_t len; 737 int r; 738 739 debug3_f("d config len %zu", sshbuf_len(conf)); 740 741 if ((m = sshbuf_new()) == NULL || 742 (inc = sshbuf_new()) == NULL) 743 fatal_f("sshbuf_new failed"); 744 745 /* pack includes into a string */ 746 TAILQ_FOREACH(item, &includes, entry) { 747 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 748 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 749 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 750 fatal_fr(r, "compose includes"); 751 } 752 753 if ((r = sshbuf_put_u32(m, 0)) != 0 || 754 (r = sshbuf_put_u8(m, 0)) != 0 || 755 (r = sshbuf_put_stringb(m, conf)) != 0 || 756 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 || 757 (r = sshbuf_put_stringb(m, inc)) != 0) 758 fatal_fr(r, "compose config"); 759 760 if ((len = sshbuf_len(m)) < 5 || len > 0xffffffff) 761 fatal_f("bad length %zu", len); 762 POKE_U32(sshbuf_mutable_ptr(m), len - 4); 763 764 sshbuf_free(inc); 765 766 debug3_f("done"); 767 return m; 768 } 769 770 /* 771 * Protocol from reexec master to child: 772 * uint32 size 773 * uint8 type (ignored) 774 * string configuration 775 * uint64 timing_secret 776 * string included_files[] { 777 * string selector 778 * string filename 779 * string contents 780 * } 781 * Second message 782 * uint32 size 783 * uint8 type (ignored) 784 * string host_keys[] { 785 * string private_key 786 * string public_key 787 * string certificate 788 * } 789 */ 790 /* 791 * This function is used only if inet_flag or debug_flag is set, 792 * otherwise the data is sent from the main poll loop. 793 * It sends the config from a child process back to the parent. 794 * The parent will read the config after exec. 795 */ 796 static void 797 send_rexec_state(int fd) 798 { 799 struct sshbuf *keys; 800 u_int mlen; 801 pid_t pid; 802 803 if ((pid = fork()) == -1) 804 fatal_f("fork failed: %s", strerror(errno)); 805 if (pid != 0) 806 return; 807 808 debug3_f("entering fd = %d config len %zu", fd, 809 sshbuf_len(config)); 810 811 mlen = sshbuf_len(config); 812 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(config), mlen) != mlen) 813 error_f("write: %s", strerror(errno)); 814 815 keys = pack_hostkeys(); 816 mlen = sshbuf_len(keys); 817 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(keys), mlen) != mlen) 818 error_f("write: %s", strerror(errno)); 819 820 sshbuf_free(keys); 821 debug3_f("done"); 822 exit(0); 823 } 824 825 /* 826 * Listen for TCP connections 827 */ 828 static void 829 listen_on_addrs(struct listenaddr *la) 830 { 831 int ret, listen_sock; 832 struct addrinfo *ai; 833 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 834 835 for (ai = la->addrs; ai; ai = ai->ai_next) { 836 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 837 continue; 838 if (num_listen_socks >= MAX_LISTEN_SOCKS) 839 fatal("Too many listen sockets. " 840 "Enlarge MAX_LISTEN_SOCKS"); 841 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 842 ntop, sizeof(ntop), strport, sizeof(strport), 843 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 844 error("getnameinfo failed: %.100s", 845 ssh_gai_strerror(ret)); 846 continue; 847 } 848 /* Create socket for listening. */ 849 listen_sock = socket(ai->ai_family, ai->ai_socktype, 850 ai->ai_protocol); 851 if (listen_sock == -1) { 852 /* kernel may not support ipv6 */ 853 verbose("socket: %.100s", strerror(errno)); 854 continue; 855 } 856 if (set_nonblock(listen_sock) == -1) { 857 close(listen_sock); 858 continue; 859 } 860 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 861 verbose("socket: CLOEXEC: %s", strerror(errno)); 862 close(listen_sock); 863 continue; 864 } 865 /* Socket options */ 866 set_reuseaddr(listen_sock); 867 if (la->rdomain != NULL && 868 set_rdomain(listen_sock, la->rdomain) == -1) { 869 close(listen_sock); 870 continue; 871 } 872 873 /* Only communicate in IPv6 over AF_INET6 sockets. */ 874 if (ai->ai_family == AF_INET6) 875 sock_set_v6only(listen_sock); 876 877 debug("Bind to port %s on %s.", strport, ntop); 878 879 /* Bind the socket to the desired port. */ 880 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 881 error("Bind to port %s on %s failed: %.200s.", 882 strport, ntop, strerror(errno)); 883 close(listen_sock); 884 continue; 885 } 886 listen_socks[num_listen_socks] = listen_sock; 887 num_listen_socks++; 888 889 /* Start listening on the port. */ 890 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 891 fatal("listen on [%s]:%s: %.100s", 892 ntop, strport, strerror(errno)); 893 logit("Server listening on %s port %s%s%s.", 894 ntop, strport, 895 la->rdomain == NULL ? "" : " rdomain ", 896 la->rdomain == NULL ? "" : la->rdomain); 897 } 898 } 899 900 static void 901 server_listen(void) 902 { 903 u_int i; 904 905 /* Initialise per-source limit tracking. */ 906 srclimit_init(options.max_startups, 907 options.per_source_max_startups, 908 options.per_source_masklen_ipv4, 909 options.per_source_masklen_ipv6, 910 &options.per_source_penalty, 911 options.per_source_penalty_exempt); 912 913 for (i = 0; i < options.num_listen_addrs; i++) { 914 listen_on_addrs(&options.listen_addrs[i]); 915 freeaddrinfo(options.listen_addrs[i].addrs); 916 free(options.listen_addrs[i].rdomain); 917 memset(&options.listen_addrs[i], 0, 918 sizeof(options.listen_addrs[i])); 919 } 920 free(options.listen_addrs); 921 options.listen_addrs = NULL; 922 options.num_listen_addrs = 0; 923 924 if (!num_listen_socks) 925 fatal("Cannot bind any address."); 926 } 927 928 /* 929 * The main TCP accept loop. Note that, for the non-debug case, returns 930 * from this function are in a forked subprocess. 931 */ 932 static void 933 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s, 934 int log_stderr) 935 { 936 struct pollfd *pfd = NULL; 937 int i, ret, npfd, r; 938 int oactive = -1, listening = 0, lameduck = 0; 939 int *startup_pollfd; 940 ssize_t len; 941 const u_char *ptr; 942 char c = 0; 943 struct sockaddr_storage from; 944 struct early_child *child; 945 struct sshbuf *buf; 946 socklen_t fromlen; 947 sigset_t nsigset, osigset; 948 #ifdef LIBWRAP 949 struct request_info req; 950 951 request_init(&req, RQ_DAEMON, __progname, 0); 952 #endif 953 954 /* pipes connected to unauthenticated child sshd processes */ 955 child_alloc(); 956 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 957 958 /* 959 * Prepare signal mask that we use to block signals that might set 960 * received_sigterm/hup/chld/info, so that we are guaranteed 961 * to immediately wake up the ppoll if a signal is received after 962 * the flag is checked. 963 */ 964 sigemptyset(&nsigset); 965 sigaddset(&nsigset, SIGHUP); 966 sigaddset(&nsigset, SIGCHLD); 967 #ifdef SIGINFO 968 sigaddset(&nsigset, SIGINFO); 969 #endif 970 sigaddset(&nsigset, SIGTERM); 971 sigaddset(&nsigset, SIGQUIT); 972 973 /* sized for worst-case */ 974 pfd = xcalloc(num_listen_socks + options.max_startups, 975 sizeof(struct pollfd)); 976 977 /* 978 * Stay listening for connections until the system crashes or 979 * the daemon is killed with a signal. 980 */ 981 for (;;) { 982 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 983 if (received_sigterm) { 984 logit("Received signal %d; terminating.", 985 (int) received_sigterm); 986 close_listen_socks(); 987 if (options.pid_file != NULL) 988 unlink(options.pid_file); 989 exit(received_sigterm == SIGTERM ? 0 : 255); 990 } 991 if (received_sigchld) { 992 child_reap_all_exited(); 993 received_sigchld = 0; 994 } 995 if (received_siginfo) { 996 show_info(); 997 received_siginfo = 0; 998 } 999 if (oactive != children_active) { 1000 setproctitle("%s [listener] %d of %d-%d startups", 1001 listener_proctitle, children_active, 1002 options.max_startups_begin, options.max_startups); 1003 oactive = children_active; 1004 } 1005 if (received_sighup) { 1006 if (!lameduck) { 1007 debug("Received SIGHUP; waiting for children"); 1008 close_listen_socks(); 1009 lameduck = 1; 1010 } 1011 if (listening <= 0) { 1012 sigprocmask(SIG_SETMASK, &osigset, NULL); 1013 sighup_restart(); 1014 } 1015 } 1016 1017 for (i = 0; i < num_listen_socks; i++) { 1018 pfd[i].fd = listen_socks[i]; 1019 pfd[i].events = POLLIN; 1020 } 1021 npfd = num_listen_socks; 1022 for (i = 0; i < options.max_startups; i++) { 1023 startup_pollfd[i] = -1; 1024 if (children[i].pipefd != -1) { 1025 pfd[npfd].fd = children[i].pipefd; 1026 pfd[npfd].events = POLLIN; 1027 if (children[i].config != NULL || 1028 children[i].keys != NULL) 1029 pfd[npfd].events |= POLLOUT; 1030 startup_pollfd[i] = npfd++; 1031 } 1032 } 1033 1034 /* Wait until a connection arrives or a child exits. */ 1035 ret = ppoll(pfd, npfd, NULL, &osigset); 1036 if (ret == -1 && errno != EINTR) { 1037 error("ppoll: %.100s", strerror(errno)); 1038 if (errno == EINVAL) 1039 cleanup_exit(1); /* can't recover */ 1040 } 1041 sigprocmask(SIG_SETMASK, &osigset, NULL); 1042 if (ret == -1) 1043 continue; 1044 1045 for (i = 0; i < options.max_startups; i++) { 1046 if (children[i].pipefd == -1 || 1047 startup_pollfd[i] == -1 || 1048 !(pfd[startup_pollfd[i]].revents & POLLOUT)) 1049 continue; 1050 if (children[i].config) 1051 buf = children[i].config; 1052 else if (children[i].keys) 1053 buf = children[i].keys; 1054 else { 1055 error_f("no buffer to send"); 1056 continue; 1057 } 1058 ptr = sshbuf_ptr(buf); 1059 len = sshbuf_len(buf); 1060 ret = write(children[i].pipefd, ptr, len); 1061 if (ret == -1 && (errno == EINTR || errno == EAGAIN)) 1062 continue; 1063 if (ret <= 0) { 1064 if (children[i].early) 1065 listening--; 1066 child_close(&(children[i]), 0, 0); 1067 continue; 1068 } 1069 if (ret == len) { 1070 /* finished sending buffer */ 1071 sshbuf_free(buf); 1072 if (children[i].config == buf) { 1073 /* sent config, now send keys */ 1074 children[i].config = NULL; 1075 children[i].keys = pack_hostkeys(); 1076 } else if (children[i].keys == buf) { 1077 /* sent both config and keys */ 1078 children[i].keys = NULL; 1079 } else { 1080 fatal("config buf not set"); 1081 } 1082 1083 } else { 1084 if ((r = sshbuf_consume(buf, ret)) != 0) 1085 fatal_fr(r, "config buf inconsistent"); 1086 } 1087 } 1088 for (i = 0; i < options.max_startups; i++) { 1089 if (children[i].pipefd == -1 || 1090 startup_pollfd[i] == -1 || 1091 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 1092 continue; 1093 switch (read(children[i].pipefd, &c, sizeof(c))) { 1094 case -1: 1095 if (errno == EINTR || errno == EAGAIN) 1096 continue; 1097 if (errno != EPIPE) { 1098 error_f("startup pipe %d (fd=%d): " 1099 "read %s", i, children[i].pipefd, 1100 strerror(errno)); 1101 } 1102 /* FALLTHROUGH */ 1103 case 0: 1104 /* child closed pipe */ 1105 if (children[i].early) 1106 listening--; 1107 debug3_f("child %lu for %s closed pipe", 1108 (long)children[i].pid, children[i].id); 1109 child_close(&(children[i]), 0, 0); 1110 break; 1111 case 1: 1112 if (children[i].config) { 1113 error_f("startup pipe %d (fd=%d)" 1114 " early read", 1115 i, children[i].pipefd); 1116 goto problem_child; 1117 } 1118 if (children[i].early && c == '\0') { 1119 /* child has finished preliminaries */ 1120 listening--; 1121 children[i].early = 0; 1122 debug2_f("child %lu for %s received " 1123 "config", (long)children[i].pid, 1124 children[i].id); 1125 } else if (!children[i].early && c == '\001') { 1126 /* child has completed auth */ 1127 debug2_f("child %lu for %s auth done", 1128 (long)children[i].pid, 1129 children[i].id); 1130 child_close(&(children[i]), 1, 0); 1131 } else { 1132 error_f("unexpected message 0x%02x " 1133 "child %ld for %s in state %d", 1134 (int)c, (long)children[i].pid, 1135 children[i].id, children[i].early); 1136 problem_child: 1137 if (children[i].early) 1138 listening--; 1139 if (children[i].pid > 0) 1140 kill(children[i].pid, SIGTERM); 1141 child_close(&(children[i]), 0, 0); 1142 } 1143 break; 1144 } 1145 } 1146 for (i = 0; i < num_listen_socks; i++) { 1147 if (!(pfd[i].revents & POLLIN)) 1148 continue; 1149 fromlen = sizeof(from); 1150 *newsock = accept(listen_socks[i], 1151 (struct sockaddr *)&from, &fromlen); 1152 if (*newsock == -1) { 1153 if (errno != EINTR && errno != EWOULDBLOCK && 1154 errno != ECONNABORTED && errno != EAGAIN) 1155 error("accept: %.100s", 1156 strerror(errno)); 1157 if (errno == EMFILE || errno == ENFILE) 1158 usleep(100 * 1000); 1159 continue; 1160 } 1161 #ifdef LIBWRAP 1162 /* Check whether logins are denied from this host. */ 1163 request_set(&req, RQ_FILE, *newsock, 1164 RQ_CLIENT_NAME, "", RQ_CLIENT_ADDR, "", 0); 1165 sock_host(&req); 1166 if (!hosts_access(&req)) { 1167 const struct linger l = { .l_onoff = 1, 1168 .l_linger = 0 }; 1169 1170 (void )setsockopt(*newsock, SOL_SOCKET, 1171 SO_LINGER, &l, sizeof(l)); 1172 (void )close(*newsock); 1173 /* 1174 * Mimic message from libwrap's refuse() as 1175 * precisely as we can afford. The authentic 1176 * message prints the IP address and the 1177 * hostname it resolves to in parentheses. If 1178 * the IP address cannot be resolved to a 1179 * hostname, the IP address will be repeated 1180 * in parentheses. As name resolution in the 1181 * main server loop could stall, and logging 1182 * resolved names adds little or no value to 1183 * incident investigation, this implementation 1184 * only repeats the IP address in parentheses. 1185 * This should resemble librwap's refuse() 1186 * closely enough not to break auditing 1187 * software like sshguard or custom scripts. 1188 */ 1189 syslog(LOG_WARNING, 1190 "refused connect from %s (%s)", 1191 eval_hostaddr(req.client), 1192 eval_hostaddr(req.client)); 1193 debug("Connection refused by tcp wrapper"); 1194 continue; 1195 } 1196 #endif /* LIBWRAP */ 1197 if (unset_nonblock(*newsock) == -1) { 1198 close(*newsock); 1199 continue; 1200 } 1201 if (socketpair(AF_UNIX, 1202 SOCK_STREAM, 0, config_s) == -1) { 1203 error("reexec socketpair: %s", 1204 strerror(errno)); 1205 close(*newsock); 1206 continue; 1207 } 1208 if (drop_connection(*newsock, 1209 children_active, config_s[0])) { 1210 close(*newsock); 1211 close(config_s[0]); 1212 close(config_s[1]); 1213 continue; 1214 } 1215 1216 /* 1217 * Got connection. Fork a child to handle it, unless 1218 * we are in debugging mode. 1219 */ 1220 if (debug_flag) { 1221 /* 1222 * In debugging mode. Close the listening 1223 * socket, and start processing the 1224 * connection without forking. 1225 */ 1226 debug("Server will not fork when running in debugging mode."); 1227 close_listen_socks(); 1228 *sock_in = *newsock; 1229 *sock_out = *newsock; 1230 send_rexec_state(config_s[0]); 1231 close(config_s[0]); 1232 free(pfd); 1233 free(startup_pollfd); 1234 return; 1235 } 1236 1237 /* 1238 * Normal production daemon. Fork, and have 1239 * the child process the connection. The 1240 * parent continues listening. 1241 */ 1242 platform_pre_fork(); 1243 set_nonblock(config_s[0]); 1244 listening++; 1245 child = child_register(config_s[0], *newsock); 1246 if ((child->pid = fork()) == 0) { 1247 /* 1248 * Child. Close the listening and 1249 * max_startup sockets. Start using 1250 * the accepted socket. Reinitialize 1251 * logging (since our pid has changed). 1252 * We return from this function to handle 1253 * the connection. 1254 */ 1255 platform_post_fork_child(); 1256 close_startup_pipes(); 1257 close_listen_socks(); 1258 *sock_in = *newsock; 1259 *sock_out = *newsock; 1260 log_init(__progname, 1261 options.log_level, 1262 options.log_facility, 1263 log_stderr); 1264 close(config_s[0]); 1265 free(pfd); 1266 free(startup_pollfd); 1267 return; 1268 } 1269 1270 /* Parent. Stay in the loop. */ 1271 platform_post_fork_parent(child->pid); 1272 if (child->pid == -1) 1273 error("fork: %.100s", strerror(errno)); 1274 else 1275 debug("Forked child %ld.", (long)child->pid); 1276 1277 close(config_s[1]); 1278 close(*newsock); 1279 1280 /* 1281 * Ensure that our random state differs 1282 * from that of the child 1283 */ 1284 reseed_prngs(); 1285 } 1286 } 1287 } 1288 1289 static void 1290 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1291 struct sshkey *key) 1292 { 1293 static struct ssh_digest_ctx *ctx; 1294 u_char *hash; 1295 size_t len; 1296 struct sshbuf *buf; 1297 int r; 1298 1299 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1300 fatal_f("ssh_digest_start"); 1301 if (key == NULL) { /* finalize */ 1302 /* add server config in case we are using agent for host keys */ 1303 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1304 sshbuf_len(server_cfg)) != 0) 1305 fatal_f("ssh_digest_update"); 1306 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1307 hash = xmalloc(len); 1308 if (ssh_digest_final(ctx, hash, len) != 0) 1309 fatal_f("ssh_digest_final"); 1310 options.timing_secret = PEEK_U64(hash); 1311 freezero(hash, len); 1312 ssh_digest_free(ctx); 1313 ctx = NULL; 1314 return; 1315 } 1316 if ((buf = sshbuf_new()) == NULL) 1317 fatal_f("could not allocate buffer"); 1318 if ((r = sshkey_private_serialize(key, buf)) != 0) 1319 fatal_fr(r, "encode %s key", sshkey_ssh_name(key)); 1320 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1321 fatal_f("ssh_digest_update"); 1322 sshbuf_reset(buf); 1323 sshbuf_free(buf); 1324 } 1325 1326 static char * 1327 prepare_proctitle(int ac, char **av) 1328 { 1329 char *ret = NULL; 1330 int i; 1331 1332 for (i = 0; i < ac; i++) 1333 xextendf(&ret, " ", "%s", av[i]); 1334 return ret; 1335 } 1336 1337 static void 1338 print_config(struct connection_info *connection_info) 1339 { 1340 connection_info->test = 1; 1341 parse_server_match_config(&options, &includes, connection_info); 1342 dump_config(&options); 1343 exit(0); 1344 } 1345 1346 /* 1347 * Main program for the daemon. 1348 */ 1349 int 1350 main(int ac, char **av) 1351 { 1352 extern char *optarg; 1353 extern int optind; 1354 int log_stderr = 0, inetd_flag = 0, test_flag = 0, no_daemon_flag = 0; 1355 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 1356 int r, opt, do_dump_cfg = 0, keytype, already_daemon, have_agent = 0; 1357 int sock_in = -1, sock_out = -1, newsock = -1, rexec_argc = 0; 1358 int devnull, config_s[2] = { -1 , -1 }, have_connection_info = 0; 1359 int need_chroot = 1; 1360 char *args, *fp, *line, *logfile = NULL, **rexec_argv = NULL; 1361 struct stat sb; 1362 u_int i, j; 1363 mode_t new_umask; 1364 struct sshkey *key; 1365 struct sshkey *pubkey; 1366 struct connection_info connection_info; 1367 struct utsname utsname; 1368 sigset_t sigmask; 1369 1370 memset(&connection_info, 0, sizeof(connection_info)); 1371 #ifdef HAVE_SECUREWARE 1372 (void)set_auth_parameters(ac, av); 1373 #endif 1374 __progname = ssh_get_progname(av[0]); 1375 1376 sigemptyset(&sigmask); 1377 sigprocmask(SIG_SETMASK, &sigmask, NULL); 1378 1379 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1380 saved_argc = ac; 1381 rexec_argc = ac; 1382 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1383 for (i = 0; (int)i < ac; i++) 1384 saved_argv[i] = xstrdup(av[i]); 1385 saved_argv[i] = NULL; 1386 1387 #ifndef HAVE_SETPROCTITLE 1388 /* Prepare for later setproctitle emulation */ 1389 compat_init_setproctitle(ac, av); 1390 av = saved_argv; 1391 #endif 1392 1393 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1394 debug("setgroups(): %.200s", strerror(errno)); 1395 1396 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1397 sanitise_stdfd(); 1398 1399 /* Initialize configuration options to their default values. */ 1400 initialize_server_options(&options); 1401 1402 /* Parse command-line arguments. */ 1403 args = argv_assemble(ac, av); /* logged later */ 1404 while ((opt = getopt(ac, av, 1405 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) { 1406 switch (opt) { 1407 case '4': 1408 options.address_family = AF_INET; 1409 break; 1410 case '6': 1411 options.address_family = AF_INET6; 1412 break; 1413 case 'f': 1414 config_file_name = optarg; 1415 break; 1416 case 'c': 1417 servconf_add_hostcert("[command-line]", 0, 1418 &options, optarg); 1419 break; 1420 case 'd': 1421 if (debug_flag == 0) { 1422 debug_flag = 1; 1423 options.log_level = SYSLOG_LEVEL_DEBUG1; 1424 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1425 options.log_level++; 1426 break; 1427 case 'D': 1428 no_daemon_flag = 1; 1429 break; 1430 case 'G': 1431 do_dump_cfg = 1; 1432 break; 1433 case 'E': 1434 logfile = optarg; 1435 /* FALLTHROUGH */ 1436 case 'e': 1437 log_stderr = 1; 1438 break; 1439 case 'i': 1440 inetd_flag = 1; 1441 break; 1442 case 'r': 1443 logit("-r option is deprecated"); 1444 break; 1445 case 'R': 1446 fatal("-R not supported here"); 1447 break; 1448 case 'Q': 1449 /* ignored */ 1450 break; 1451 case 'q': 1452 options.log_level = SYSLOG_LEVEL_QUIET; 1453 break; 1454 case 'b': 1455 /* protocol 1, ignored */ 1456 break; 1457 case 'p': 1458 options.ports_from_cmdline = 1; 1459 if (options.num_ports >= MAX_PORTS) { 1460 fprintf(stderr, "too many ports.\n"); 1461 exit(1); 1462 } 1463 options.ports[options.num_ports++] = a2port(optarg); 1464 if (options.ports[options.num_ports-1] <= 0) { 1465 fprintf(stderr, "Bad port number.\n"); 1466 exit(1); 1467 } 1468 break; 1469 case 'g': 1470 if ((options.login_grace_time = convtime(optarg)) == -1) { 1471 fprintf(stderr, "Invalid login grace time.\n"); 1472 exit(1); 1473 } 1474 break; 1475 case 'k': 1476 /* protocol 1, ignored */ 1477 break; 1478 case 'h': 1479 servconf_add_hostkey("[command-line]", 0, 1480 &options, optarg, 1); 1481 break; 1482 case 't': 1483 test_flag = 1; 1484 break; 1485 case 'T': 1486 test_flag = 2; 1487 break; 1488 case 'C': 1489 if (parse_server_match_testspec(&connection_info, 1490 optarg) == -1) 1491 exit(1); 1492 have_connection_info = 1; 1493 break; 1494 case 'u': 1495 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1496 if (utmp_len > HOST_NAME_MAX+1) { 1497 fprintf(stderr, "Invalid utmp length.\n"); 1498 exit(1); 1499 } 1500 break; 1501 case 'o': 1502 line = xstrdup(optarg); 1503 if (process_server_config_line(&options, line, 1504 "command-line", 0, NULL, NULL, &includes) != 0) 1505 exit(1); 1506 free(line); 1507 break; 1508 case 'V': 1509 fprintf(stderr, "%s, %s\n", 1510 SSH_RELEASE, SSH_OPENSSL_VERSION); 1511 exit(0); 1512 default: 1513 usage(); 1514 break; 1515 } 1516 } 1517 if (!test_flag && !inetd_flag && !do_dump_cfg && !path_absolute(av[0])) 1518 fatal("sshd requires execution with an absolute path"); 1519 1520 closefrom(STDERR_FILENO + 1); 1521 1522 /* Reserve fds we'll need later for reexec things */ 1523 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) 1524 fatal("open %s: %s", _PATH_DEVNULL, strerror(errno)); 1525 while (devnull < REEXEC_MIN_FREE_FD) { 1526 if ((devnull = dup(devnull)) == -1) 1527 fatal("dup %s: %s", _PATH_DEVNULL, strerror(errno)); 1528 } 1529 1530 seed_rng(); 1531 1532 /* If requested, redirect the logs to the specified logfile. */ 1533 if (logfile != NULL) { 1534 char *cp, pid_s[32]; 1535 1536 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid()); 1537 cp = percent_expand(logfile, 1538 "p", pid_s, 1539 "P", "sshd", 1540 (char *)NULL); 1541 log_redirect_stderr_to(cp); 1542 free(cp); 1543 } 1544 1545 /* 1546 * Force logging to stderr until we have loaded the private host 1547 * key (unless started from inetd) 1548 */ 1549 log_init(__progname, 1550 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1551 SYSLOG_LEVEL_INFO : options.log_level, 1552 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1553 SYSLOG_FACILITY_AUTH : options.log_facility, 1554 log_stderr || !inetd_flag || debug_flag); 1555 1556 /* 1557 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1558 * root's environment 1559 */ 1560 if (getenv("KRB5CCNAME") != NULL) 1561 (void) unsetenv("KRB5CCNAME"); 1562 1563 sensitive_data.have_ssh2_key = 0; 1564 1565 /* 1566 * If we're not doing an extended test do not silently ignore connection 1567 * test params. 1568 */ 1569 if (test_flag < 2 && have_connection_info) 1570 fatal("Config test connection parameter (-C) provided without " 1571 "test mode (-T)"); 1572 1573 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1574 if (uname(&utsname) != 0) { 1575 memset(&utsname, 0, sizeof(utsname)); 1576 strlcpy(utsname.sysname, "UNKNOWN", sizeof(utsname.sysname)); 1577 } 1578 debug3("Running on %s %s %s %s", utsname.sysname, utsname.release, 1579 utsname.version, utsname.machine); 1580 debug3("Started with: %s", args); 1581 free(args); 1582 1583 /* Fetch our configuration */ 1584 if ((cfg = sshbuf_new()) == NULL) 1585 fatal("sshbuf_new config failed"); 1586 if (strcasecmp(config_file_name, "none") != 0) 1587 load_server_config(config_file_name, cfg); 1588 1589 parse_server_config(&options, config_file_name, cfg, 1590 &includes, NULL, 0); 1591 1592 /* Fill in default values for those options not explicitly set. */ 1593 fill_default_server_options(&options); 1594 1595 /* Check that options are sensible */ 1596 if (options.authorized_keys_command_user == NULL && 1597 (options.authorized_keys_command != NULL && 1598 strcasecmp(options.authorized_keys_command, "none") != 0)) 1599 fatal("AuthorizedKeysCommand set without " 1600 "AuthorizedKeysCommandUser"); 1601 if (options.authorized_principals_command_user == NULL && 1602 (options.authorized_principals_command != NULL && 1603 strcasecmp(options.authorized_principals_command, "none") != 0)) 1604 fatal("AuthorizedPrincipalsCommand set without " 1605 "AuthorizedPrincipalsCommandUser"); 1606 1607 /* 1608 * Check whether there is any path through configured auth methods. 1609 * Unfortunately it is not possible to verify this generally before 1610 * daemonisation in the presence of Match blocks, but this catches 1611 * and warns for trivial misconfigurations that could break login. 1612 */ 1613 if (options.num_auth_methods != 0) { 1614 for (i = 0; i < options.num_auth_methods; i++) { 1615 if (auth2_methods_valid(options.auth_methods[i], 1616 1) == 0) 1617 break; 1618 } 1619 if (i >= options.num_auth_methods) 1620 fatal("AuthenticationMethods cannot be satisfied by " 1621 "enabled authentication methods"); 1622 } 1623 1624 /* Check that there are no remaining arguments. */ 1625 if (optind < ac) { 1626 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1627 exit(1); 1628 } 1629 1630 if (do_dump_cfg) 1631 print_config(&connection_info); 1632 1633 /* load host keys */ 1634 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1635 sizeof(struct sshkey *)); 1636 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1637 sizeof(struct sshkey *)); 1638 1639 if (options.host_key_agent) { 1640 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1641 setenv(SSH_AUTHSOCKET_ENV_NAME, 1642 options.host_key_agent, 1); 1643 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1644 have_agent = 1; 1645 else 1646 error_r(r, "Could not connect to agent \"%s\"", 1647 options.host_key_agent); 1648 } 1649 1650 for (i = 0; i < options.num_host_key_files; i++) { 1651 int ll = options.host_key_file_userprovided[i] ? 1652 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1653 1654 if (options.host_key_files[i] == NULL) 1655 continue; 1656 if ((r = sshkey_load_private(options.host_key_files[i], "", 1657 &key, NULL)) != 0 && 1658 r != SSH_ERR_SYSTEM_ERROR && !have_agent) 1659 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1660 options.host_key_files[i]); 1661 if (sshkey_is_sk(key) && 1662 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1663 debug("host key %s requires user presence, ignoring", 1664 options.host_key_files[i]); 1665 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1666 } 1667 if (r == 0 && key != NULL && 1668 (r = sshkey_shield_private(key)) != 0) { 1669 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1670 options.host_key_files[i]); 1671 sshkey_free(key); 1672 key = NULL; 1673 } 1674 if ((r = sshkey_load_public(options.host_key_files[i], 1675 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1676 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1677 options.host_key_files[i]); 1678 if (pubkey != NULL && key != NULL) { 1679 if (!sshkey_equal(pubkey, key)) { 1680 error("Public key for %s does not match " 1681 "private key", options.host_key_files[i]); 1682 sshkey_free(pubkey); 1683 pubkey = NULL; 1684 } 1685 } 1686 if (pubkey == NULL && key != NULL) { 1687 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1688 fatal_r(r, "Could not demote key: \"%s\"", 1689 options.host_key_files[i]); 1690 } 1691 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1692 options.required_rsa_size)) != 0) { 1693 error_fr(r, "Host key %s", options.host_key_files[i]); 1694 sshkey_free(pubkey); 1695 sshkey_free(key); 1696 continue; 1697 } 1698 sensitive_data.host_keys[i] = key; 1699 sensitive_data.host_pubkeys[i] = pubkey; 1700 1701 if (key == NULL && pubkey != NULL && have_agent) { 1702 debug("will rely on agent for hostkey %s", 1703 options.host_key_files[i]); 1704 keytype = pubkey->type; 1705 } else if (key != NULL) { 1706 keytype = key->type; 1707 accumulate_host_timing_secret(cfg, key); 1708 } else { 1709 do_log2(ll, "Unable to load host key: %s", 1710 options.host_key_files[i]); 1711 sensitive_data.host_keys[i] = NULL; 1712 sensitive_data.host_pubkeys[i] = NULL; 1713 continue; 1714 } 1715 1716 switch (keytype) { 1717 case KEY_RSA: 1718 case KEY_ECDSA: 1719 case KEY_ED25519: 1720 case KEY_MLDSA44_ED25519: 1721 case KEY_ECDSA_SK: 1722 case KEY_ED25519_SK: 1723 if (have_agent || key != NULL) 1724 sensitive_data.have_ssh2_key = 1; 1725 break; 1726 } 1727 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1728 SSH_FP_DEFAULT)) == NULL) 1729 fatal("sshkey_fingerprint failed"); 1730 debug("%s host key #%d: %s %s", 1731 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1732 free(fp); 1733 } 1734 accumulate_host_timing_secret(cfg, NULL); 1735 if (!sensitive_data.have_ssh2_key) { 1736 logit("sshd: no hostkeys available -- exiting."); 1737 exit(1); 1738 } 1739 1740 /* 1741 * Load certificates. They are stored in an array at identical 1742 * indices to the public keys that they relate to. 1743 */ 1744 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1745 sizeof(struct sshkey *)); 1746 for (i = 0; i < options.num_host_key_files; i++) 1747 sensitive_data.host_certificates[i] = NULL; 1748 1749 for (i = 0; i < options.num_host_cert_files; i++) { 1750 if (options.host_cert_files[i] == NULL) 1751 continue; 1752 if ((r = sshkey_load_public(options.host_cert_files[i], 1753 &key, NULL)) != 0) { 1754 error_r(r, "Could not load host certificate \"%s\"", 1755 options.host_cert_files[i]); 1756 continue; 1757 } 1758 if (!sshkey_is_cert(key)) { 1759 error("Certificate file is not a certificate: %s", 1760 options.host_cert_files[i]); 1761 sshkey_free(key); 1762 continue; 1763 } 1764 /* Find matching private key */ 1765 for (j = 0; j < options.num_host_key_files; j++) { 1766 if (sshkey_equal_public(key, 1767 sensitive_data.host_pubkeys[j])) { 1768 sensitive_data.host_certificates[j] = key; 1769 break; 1770 } 1771 } 1772 if (j >= options.num_host_key_files) { 1773 error("No matching private key for certificate: %s", 1774 options.host_cert_files[i]); 1775 sshkey_free(key); 1776 continue; 1777 } 1778 sensitive_data.host_certificates[j] = key; 1779 debug("host certificate: #%u type %d %s", j, key->type, 1780 sshkey_type(key)); 1781 } 1782 1783 /* Ensure privsep directory is correctly configured. */ 1784 need_chroot = ((getuid() == 0 || geteuid() == 0) || 1785 options.kerberos_authentication); 1786 if ((getpwnam(SSH_PRIVSEP_USER)) == NULL && need_chroot) { 1787 fatal("Privilege separation user %s does not exist", 1788 SSH_PRIVSEP_USER); 1789 } 1790 endpwent(); 1791 1792 if (need_chroot) { 1793 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &sb) == -1) || 1794 (S_ISDIR(sb.st_mode) == 0)) 1795 fatal("Missing privilege separation directory: %s", 1796 _PATH_PRIVSEP_CHROOT_DIR); 1797 #ifdef HAVE_CYGWIN 1798 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1799 (sb.st_uid != getuid () || 1800 (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1801 #else 1802 if (sb.st_uid != 0 || (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1803 #endif 1804 fatal("%s must be owned by root and not group or " 1805 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1806 } 1807 1808 if (test_flag > 1) 1809 print_config(&connection_info); 1810 1811 config = pack_config(cfg); 1812 if (sshbuf_len(config) > MONITOR_MAX_CFGLEN) { 1813 fatal("Configuration file is too large (have %zu, max %d)", 1814 sshbuf_len(config), MONITOR_MAX_CFGLEN); 1815 } 1816 1817 /* Configuration looks good, so exit if in test mode. */ 1818 if (test_flag) 1819 exit(0); 1820 1821 /* 1822 * Clear out any supplemental groups we may have inherited. This 1823 * prevents inadvertent creation of files with bad modes (in the 1824 * portable version at least, it's certainly possible for PAM 1825 * to create a file, and we can't control the code in every 1826 * module which might be used). 1827 */ 1828 if (setgroups(0, NULL) < 0) 1829 debug("setgroups() failed: %.200s", strerror(errno)); 1830 1831 /* Prepare arguments for sshd-session */ 1832 if (rexec_argc < 0) 1833 fatal("rexec_argc %d < 0", rexec_argc); 1834 rexec_argv = xcalloc(rexec_argc + 3, sizeof(char *)); 1835 /* Point to the sshd-session binary instead of sshd */ 1836 rexec_argv[0] = options.sshd_session_path; 1837 for (i = 1; i < (u_int)rexec_argc; i++) { 1838 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1839 rexec_argv[i] = saved_argv[i]; 1840 } 1841 rexec_argv[rexec_argc++] = "-R"; 1842 rexec_argv[rexec_argc] = NULL; 1843 if (stat(rexec_argv[0], &sb) != 0 || !(sb.st_mode & (S_IXOTH|S_IXUSR))) 1844 fatal("%s does not exist or is not executable", rexec_argv[0]); 1845 debug3("using %s for re-exec", rexec_argv[0]); 1846 1847 /* Ensure that the privsep binary exists now too. */ 1848 if (stat(options.sshd_auth_path, &sb) != 0 || 1849 !(sb.st_mode & (S_IXOTH|S_IXUSR))) { 1850 fatal("%s does not exist or is not executable", 1851 options.sshd_auth_path); 1852 } 1853 1854 listener_proctitle = prepare_proctitle(ac, av); 1855 1856 /* Ensure that umask disallows at least group and world write */ 1857 new_umask = umask(0077) | 0022; 1858 (void) umask(new_umask); 1859 1860 /* Initialize the log (it is reinitialized below in case we forked). */ 1861 if (debug_flag && !inetd_flag) 1862 log_stderr = 1; 1863 log_init(__progname, options.log_level, 1864 options.log_facility, log_stderr); 1865 for (i = 0; i < options.num_log_verbose; i++) 1866 log_verbose_add(options.log_verbose[i]); 1867 1868 /* 1869 * If not in debugging mode, not started from inetd and not already 1870 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1871 * terminal, and fork. The original process exits. 1872 */ 1873 already_daemon = daemonized(); 1874 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1875 1876 if (daemon(0, 0) == -1) 1877 fatal("daemon() failed: %.200s", strerror(errno)); 1878 1879 disconnect_controlling_tty(); 1880 } 1881 /* Reinitialize the log (because of the fork above). */ 1882 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1883 1884 /* Avoid killing the process in high-pressure swapping environments. */ 1885 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1886 debug("madvise(): %.200s", strerror(errno)); 1887 1888 /* 1889 * Chdir to the root directory so that the current disk can be 1890 * unmounted if desired. 1891 */ 1892 if (chdir("/") == -1) 1893 error("chdir(\"/\"): %s", strerror(errno)); 1894 1895 /* ignore SIGPIPE */ 1896 ssh_signal(SIGPIPE, SIG_IGN); 1897 1898 /* Get a connection, either from inetd or a listening TCP socket */ 1899 if (inetd_flag) { 1900 /* Send configuration to ancestor sshd-session process */ 1901 if (socketpair(AF_UNIX, SOCK_STREAM, 0, config_s) == -1) 1902 fatal("socketpair: %s", strerror(errno)); 1903 send_rexec_state(config_s[0]); 1904 close(config_s[0]); 1905 } else { 1906 platform_pre_listen(); 1907 server_listen(); 1908 1909 ssh_signal(SIGHUP, sighup_handler); 1910 ssh_signal(SIGCHLD, main_sigchld_handler); 1911 ssh_signal(SIGTERM, sigterm_handler); 1912 ssh_signal(SIGQUIT, sigterm_handler); 1913 #ifdef SIGINFO 1914 ssh_signal(SIGINFO, siginfo_handler); 1915 #endif 1916 1917 platform_post_listen(); 1918 1919 /* 1920 * Write out the pid file after the sigterm handler 1921 * is setup and the listen sockets are bound 1922 */ 1923 if (options.pid_file != NULL && !debug_flag) { 1924 FILE *f = fopen(options.pid_file, "w"); 1925 1926 if (f == NULL) { 1927 error("Couldn't create pid file \"%s\": %s", 1928 options.pid_file, strerror(errno)); 1929 } else { 1930 fprintf(f, "%ld\n", (long) getpid()); 1931 fclose(f); 1932 } 1933 } 1934 1935 /* Accept a connection and return in a forked child */ 1936 server_accept_loop(&sock_in, &sock_out, 1937 &newsock, config_s, log_stderr); 1938 } 1939 1940 /* This is the child processing a new connection. */ 1941 setproctitle("%s", "[accepted]"); 1942 1943 /* 1944 * Create a new session and process group since the 4.4BSD 1945 * setlogin() affects the entire process group. We don't 1946 * want the child to be able to affect the parent. 1947 */ 1948 if (!debug_flag && !inetd_flag && setsid() == -1) 1949 error("setsid: %.100s", strerror(errno)); 1950 1951 debug("rexec start in %d out %d newsock %d config_s %d/%d", 1952 sock_in, sock_out, newsock, config_s[0], config_s[1]); 1953 if (!inetd_flag) { 1954 if (dup2(newsock, STDIN_FILENO) == -1) 1955 fatal("dup2 stdin: %s", strerror(errno)); 1956 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1) 1957 fatal("dup2 stdout: %s", strerror(errno)); 1958 if (newsock > STDOUT_FILENO) 1959 close(newsock); 1960 } 1961 if (config_s[1] != REEXEC_CONFIG_PASS_FD) { 1962 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1) 1963 fatal("dup2 config_s: %s", strerror(errno)); 1964 close(config_s[1]); 1965 } 1966 log_redirect_stderr_to(NULL); 1967 closefrom(REEXEC_MIN_FREE_FD); 1968 1969 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1970 execv(rexec_argv[0], rexec_argv); 1971 1972 fatal("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1973 #ifdef __FreeBSD__ 1974 /* 1975 * Initialize the resolver. This may not happen automatically 1976 * before privsep chroot(). 1977 */ 1978 if ((_res.options & RES_INIT) == 0) { 1979 debug("res_init()"); 1980 res_init(); 1981 } 1982 #ifdef GSSAPI 1983 /* 1984 * Force GSS-API to parse its configuration and load any 1985 * mechanism plugins. 1986 */ 1987 { 1988 gss_OID_set mechs; 1989 OM_uint32 minor_status; 1990 gss_indicate_mechs(&minor_status, &mechs); 1991 gss_release_oid_set(&minor_status, &mechs); 1992 } 1993 #endif 1994 #endif 1995 } 1996 1997 /* server specific fatal cleanup */ 1998 void 1999 cleanup_exit(int i) 2000 { 2001 _exit(i); 2002 } 2003