1 /* $NetBSD: sshd.c,v 1.57 2026/04/08 18:58:41 christos Exp $ */ 2 /* $OpenBSD: sshd.c,v 1.626 2026/02/09 21:21:39 dtucker Exp $ */ 3 4 /* 5 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 6 * Copyright (c) 2002 Niels Provos. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include "includes.h" 30 __RCSID("$NetBSD: sshd.c,v 1.57 2026/04/08 18:58:41 christos Exp $"); 31 #include <sys/types.h> 32 #include <sys/param.h> 33 #include <sys/ioctl.h> 34 #include <sys/wait.h> 35 #include <sys/tree.h> 36 #include <sys/stat.h> 37 #include <sys/socket.h> 38 #include <sys/time.h> 39 #include <sys/queue.h> 40 #include <sys/utsname.h> 41 42 #include <errno.h> 43 #include <fcntl.h> 44 #include <netdb.h> 45 #include <paths.h> 46 #include <poll.h> 47 #include <pwd.h> 48 #include <signal.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <stdarg.h> 53 #include <time.h> 54 #include <unistd.h> 55 #include <limits.h> 56 57 #include "xmalloc.h" 58 #include "ssh.h" 59 #include "sshpty.h" 60 #include "log.h" 61 #include "sshbuf.h" 62 #include "misc.h" 63 #include "servconf.h" 64 #include "compat.h" 65 #include "digest.h" 66 #include "sshkey.h" 67 #include "authfile.h" 68 #include "pathnames.h" 69 #include "canohost.h" 70 #include "hostfile.h" 71 #include "auth.h" 72 #include "authfd.h" 73 #include "misc.h" 74 #include "msg.h" 75 #include "version.h" 76 #include "ssherr.h" 77 #include "sk-api.h" 78 #include "addr.h" 79 #include "srclimit.h" 80 #include "atomicio.h" 81 #ifdef GSSAPI 82 #include "ssh-gss.h" 83 #endif 84 #include "monitor_wrap.h" 85 86 #ifdef LIBWRAP 87 #include <tcpd.h> 88 #include <syslog.h> 89 int allow_severity = LOG_INFO; 90 int deny_severity = LOG_WARNING; 91 #endif /* LIBWRAP */ 92 93 #ifdef WITH_LDAP_PUBKEY 94 #include "ldapauth.h" 95 #endif 96 97 #ifndef HOST_NAME_MAX 98 #define HOST_NAME_MAX MAXHOSTNAMELEN 99 #endif 100 101 /* Re-exec fds */ 102 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 103 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 2) 104 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 3) 105 106 extern char *__progname; 107 108 /* Server configuration options. */ 109 ServerOptions options; 110 111 /* 112 * Debug mode flag. This can be set on the command line. If debug 113 * mode is enabled, extra debugging output will be sent to the system 114 * log, the daemon will not go to background, and will exit after processing 115 * the first connection. 116 */ 117 int debug_flag = 0; 118 119 /* Saved arguments to main(). */ 120 static char **saved_argv; 121 122 /* 123 * The sockets that the server is listening; this is used in the SIGHUP 124 * signal handler. 125 */ 126 #define MAX_LISTEN_SOCKS 16 127 static int listen_socks[MAX_LISTEN_SOCKS]; 128 static int num_listen_socks = 0; 129 130 /* 131 * Any really sensitive data in the application is contained in this 132 * structure. The idea is that this structure could be locked into memory so 133 * that the pages do not get written into swap. However, there are some 134 * problems. The private key contains BIGNUMs, and we do not (in principle) 135 * have access to the internals of them, and locking just the structure is 136 * not very useful. Currently, memory locking is not implemented. 137 */ 138 struct { 139 struct sshkey **host_keys; /* all private host keys */ 140 struct sshkey **host_pubkeys; /* all public host keys */ 141 struct sshkey **host_certificates; /* all public host certificates */ 142 int have_ssh2_key; 143 } sensitive_data; 144 145 /* This is set to true when a signal is received. */ 146 static volatile sig_atomic_t received_siginfo = 0; 147 static volatile sig_atomic_t received_sigchld = 0; 148 static volatile sig_atomic_t received_sighup = 0; 149 static volatile sig_atomic_t received_sigterm = 0; 150 151 /* record remote hostname or ip */ 152 u_int utmp_len = HOST_NAME_MAX+1; 153 154 /* 155 * The early_child/children array below is used for tracking children of the 156 * listening sshd process early in their lifespans, before they have 157 * completed authentication. This tracking is needed for four things: 158 * 159 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 160 * connections. 161 * 2) Avoiding a race condition for SIGHUP processing, where child processes 162 * may have listen_socks open that could collide with main listener process 163 * after it restarts. 164 * 3) Ensuring that rexec'd sshd processes have received their initial state 165 * from the parent listen process before handling SIGHUP. 166 * 4) Tracking and logging unsuccessful exits from the preauth sshd monitor, 167 * including and especially those for LoginGraceTime timeouts. 168 * 169 * Child processes signal that they have completed closure of the listen_socks 170 * and (if applicable) received their rexec state by sending a char over their 171 * sock. 172 * 173 * Child processes signal that authentication has completed by sending a 174 * second char over the socket before closing it, otherwise the listener will 175 * continue tracking the child (and using up a MaxStartups slot) until the 176 * preauth subprocess exits, whereupon the listener will log its exit status. 177 * preauth processes will exit with a status of EXIT_LOGIN_GRACE to indicate 178 * they did not authenticate before the LoginGraceTime alarm fired. 179 */ 180 struct early_child { 181 int pipefd; 182 int early; /* Indicates child closed listener */ 183 char *id; /* human readable connection identifier */ 184 pid_t pid; 185 struct xaddr addr; 186 int have_addr; 187 int status, have_status; 188 struct sshbuf *config; 189 struct sshbuf *keys; 190 }; 191 static struct early_child *children; 192 static int children_active; 193 194 /* sshd_config buffer */ 195 struct sshbuf *cfg; 196 struct sshbuf *config; /* packed */ 197 198 /* Included files from the configuration file */ 199 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 200 201 /* message to be displayed after login */ 202 struct sshbuf *loginmsg; 203 204 static char *listener_proctitle; 205 206 /* 207 * Close all listening sockets 208 */ 209 static void 210 close_listen_socks(void) 211 { 212 int i; 213 214 for (i = 0; i < num_listen_socks; i++) 215 close(listen_socks[i]); 216 num_listen_socks = 0; 217 } 218 219 /* Allocate and initialise the children array */ 220 static void 221 child_alloc(void) 222 { 223 int i; 224 225 children = xcalloc(options.max_startups, sizeof(*children)); 226 for (i = 0; i < options.max_startups; i++) { 227 children[i].pipefd = -1; 228 children[i].pid = -1; 229 } 230 } 231 232 /* Register a new connection in the children array; child pid comes later */ 233 static struct early_child * 234 child_register(int pipefd, int sockfd) 235 { 236 int i, lport, rport; 237 char *laddr = NULL, *raddr = NULL; 238 struct early_child *child = NULL; 239 struct sockaddr_storage addr; 240 socklen_t addrlen = sizeof(addr); 241 struct sockaddr *sa = (struct sockaddr *)&addr; 242 243 for (i = 0; i < options.max_startups; i++) { 244 if (children[i].pipefd != -1 || 245 children[i].config != NULL || 246 children[i].keys != NULL || 247 children[i].pid > 0) 248 continue; 249 child = &(children[i]); 250 break; 251 } 252 if (child == NULL) { 253 fatal_f("error: accepted connection when all %d child " 254 " slots full", options.max_startups); 255 } 256 child->pipefd = pipefd; 257 child->early = 1; 258 if ((child->config = sshbuf_fromb(config)) == NULL) 259 fatal_f("sshbuf_fromb failed"); 260 /* record peer address, if available */ 261 if (getpeername(sockfd, sa, &addrlen) == 0 && 262 addr_sa_to_xaddr(sa, addrlen, &child->addr) == 0) 263 child->have_addr = 1; 264 /* format peer address string for logs */ 265 if ((lport = get_local_port(sockfd)) == 0 || 266 (rport = get_peer_port(sockfd)) == 0) { 267 /* Not a TCP socket */ 268 raddr = get_peer_ipaddr(sockfd); 269 xasprintf(&child->id, "connection from %s", raddr); 270 } else { 271 laddr = get_local_ipaddr(sockfd); 272 raddr = get_peer_ipaddr(sockfd); 273 xasprintf(&child->id, "connection from %s to %s", raddr, laddr); 274 } 275 free(laddr); 276 free(raddr); 277 if (++children_active > options.max_startups) 278 fatal_f("internal error: more children than max_startups"); 279 280 return child; 281 } 282 283 /* 284 * Finally free a child entry. Don't call this directly. 285 */ 286 static void 287 child_finish(struct early_child *child) 288 { 289 if (children_active == 0) 290 fatal_f("internal error: children_active underflow"); 291 if (child->pipefd != -1) { 292 srclimit_done(child->pipefd); 293 close(child->pipefd); 294 } 295 sshbuf_free(child->config); 296 sshbuf_free(child->keys); 297 free(child->id); 298 memset(child, '\0', sizeof(*child)); 299 child->pipefd = -1; 300 child->pid = -1; 301 children_active--; 302 } 303 304 /* 305 * Close a child's pipe. This will not stop tracking the child immediately 306 * (it will still be tracked for waitpid()) unless force_final is set, or 307 * child has already exited. 308 */ 309 static void 310 child_close(struct early_child *child, int force_final, int quiet) 311 { 312 if (!quiet) 313 debug_f("enter%s", force_final ? " (forcing)" : ""); 314 if (child->pipefd != -1) { 315 srclimit_done(child->pipefd); 316 close(child->pipefd); 317 child->pipefd = -1; 318 } 319 if (child->pid == -1 || force_final) 320 child_finish(child); 321 } 322 323 /* Record a child exit. Safe to call from signal handlers */ 324 static void 325 child_exit(pid_t pid, int status) 326 { 327 int i; 328 329 if (children == NULL || pid <= 0) 330 return; 331 for (i = 0; i < options.max_startups; i++) { 332 if (children[i].pid == pid) { 333 children[i].have_status = 1; 334 children[i].status = status; 335 break; 336 } 337 } 338 } 339 340 /* 341 * Reap a child entry that has exited, as previously flagged 342 * using child_exit(). 343 * Handles logging of exit condition and will finalise the child if its pipe 344 * had already been closed. 345 */ 346 static void 347 child_reap(struct early_child *child) 348 { 349 LogLevel level = SYSLOG_LEVEL_DEBUG1; 350 int was_crash, penalty_type = SRCLIMIT_PENALTY_NONE; 351 const char *child_status; 352 353 if (child->config) 354 child_status = " (sending config)"; 355 else if (child->keys) 356 child_status = " (sending keys)"; 357 else if (child->early) 358 child_status = " (early)"; 359 else 360 child_status = ""; 361 362 /* Log exit information */ 363 if (WIFSIGNALED(child->status)) { 364 /* 365 * Increase logging for signals potentially associated 366 * with serious conditions. 367 */ 368 if ((was_crash = signal_is_crash(WTERMSIG(child->status)))) 369 level = SYSLOG_LEVEL_ERROR; 370 do_log2(level, "session process %ld for %s killed by " 371 "signal %d%s", (long)child->pid, child->id, 372 WTERMSIG(child->status), child_status); 373 if (was_crash) 374 penalty_type = SRCLIMIT_PENALTY_CRASH; 375 } else if (!WIFEXITED(child->status)) { 376 penalty_type = SRCLIMIT_PENALTY_CRASH; 377 error("session process %ld for %s terminated abnormally, " 378 "status=0x%x%s", (long)child->pid, child->id, child->status, 379 child_status); 380 } else { 381 /* Normal exit. We care about the status */ 382 switch (WEXITSTATUS(child->status)) { 383 case 0: 384 debug3_f("preauth child %ld for %s completed " 385 "normally%s", (long)child->pid, child->id, 386 child_status); 387 break; 388 case EXIT_LOGIN_GRACE: 389 penalty_type = SRCLIMIT_PENALTY_GRACE_EXCEEDED; 390 logit("Timeout before authentication for %s, " 391 "pid = %ld%s", child->id, (long)child->pid, 392 child_status); 393 break; 394 case EXIT_CHILD_CRASH: 395 penalty_type = SRCLIMIT_PENALTY_CRASH; 396 logit("Session process %ld unpriv child crash for %s%s", 397 (long)child->pid, child->id, child_status); 398 break; 399 case EXIT_AUTH_ATTEMPTED: 400 penalty_type = SRCLIMIT_PENALTY_AUTHFAIL; 401 debug_f("preauth child %ld for %s exited " 402 "after unsuccessful auth attempt%s", 403 (long)child->pid, child->id, child_status); 404 break; 405 case EXIT_INVALID_USER: 406 penalty_type = SRCLIMIT_PENALTY_INVALIDUSER; 407 debug_f("preauth child %ld for %s exited " 408 "after auth attempt by invalid user%s", 409 (long)child->pid, child->id, child_status); 410 break; 411 case EXIT_CONFIG_REFUSED: 412 penalty_type = SRCLIMIT_PENALTY_REFUSECONNECTION; 413 debug_f("preauth child %ld for %s prohibited by" 414 "RefuseConnection%s", 415 (long)child->pid, child->id, child_status); 416 break; 417 default: 418 penalty_type = SRCLIMIT_PENALTY_NOAUTH; 419 debug_f("preauth child %ld for %s exited " 420 "with status %d%s", (long)child->pid, child->id, 421 WEXITSTATUS(child->status), child_status); 422 break; 423 } 424 } 425 426 if (child->have_addr) 427 srclimit_penalise(&child->addr, penalty_type); 428 429 child->pid = -1; 430 child->have_status = 0; 431 if (child->pipefd == -1) 432 child_finish(child); 433 } 434 435 /* Reap all children that have exited; called after SIGCHLD */ 436 static void 437 child_reap_all_exited(void) 438 { 439 int i; 440 pid_t pid; 441 int status; 442 443 if (children == NULL) 444 return; 445 446 for (;;) { 447 if ((pid = waitpid(-1, &status, WNOHANG)) == 0) 448 break; 449 else if (pid == -1) { 450 if (errno == EINTR || errno == EAGAIN) 451 continue; 452 if (errno != ECHILD) 453 error_f("waitpid: %s", strerror(errno)); 454 break; 455 } 456 child_exit(pid, status); 457 } 458 459 for (i = 0; i < options.max_startups; i++) { 460 if (!children[i].have_status) 461 continue; 462 child_reap(&(children[i])); 463 } 464 } 465 466 static void 467 close_startup_pipes(void) 468 { 469 int i; 470 471 if (children == NULL) 472 return; 473 for (i = 0; i < options.max_startups; i++) { 474 if (children[i].pipefd != -1) 475 child_close(&(children[i]), 1, 1); 476 } 477 } 478 479 /* Called after SIGINFO */ 480 static void 481 show_info(void) 482 { 483 int i; 484 const char *child_status; 485 486 /* XXX print listening sockets here too */ 487 if (children == NULL) 488 return; 489 logit("%d active startups", children_active); 490 for (i = 0; i < options.max_startups; i++) { 491 if (children[i].pipefd == -1 && children[i].pid <= 0) 492 continue; 493 if (children[i].config) 494 child_status = " (sending config)"; 495 else if (children[i].keys) 496 child_status = " (sending keys)"; 497 else if (children[i].early) 498 child_status = " (early)"; 499 else 500 child_status = ""; 501 logit("child %d: fd=%d pid=%ld %s%s", i, children[i].pipefd, 502 (long)children[i].pid, children[i].id, child_status); 503 } 504 srclimit_penalty_info(); 505 } 506 507 /* 508 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 509 * the effect is to reread the configuration file (and to regenerate 510 * the server key). 511 */ 512 513 static void 514 sighup_handler(int sig) 515 { 516 received_sighup = 1; 517 } 518 519 /* 520 * Called from the main program after receiving SIGHUP. 521 * Restarts the server. 522 */ 523 __dead 524 static void 525 sighup_restart(void) 526 { 527 logit("Received SIGHUP; restarting."); 528 if (options.pid_file != NULL) 529 unlink(options.pid_file); 530 close_listen_socks(); 531 close_startup_pipes(); 532 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 533 execv(saved_argv[0], saved_argv); 534 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 535 strerror(errno)); 536 exit(1); 537 } 538 539 /* 540 * Generic signal handler for terminating signals in the master daemon. 541 */ 542 static void 543 sigterm_handler(int sig) 544 { 545 received_sigterm = sig; 546 } 547 548 static void 549 siginfo_handler(int sig) 550 { 551 received_siginfo = 1; 552 } 553 554 static void 555 main_sigchld_handler(int sig) 556 { 557 received_sigchld = 1; 558 } 559 560 /* 561 * returns 1 if connection should be dropped, 0 otherwise. 562 * dropping starts at connection #max_startups_begin with a probability 563 * of (max_startups_rate/100). the probability increases linearly until 564 * all connections are dropped for startups > max_startups 565 */ 566 static int 567 should_drop_connection(int startups) 568 { 569 int p, r; 570 571 if (startups < options.max_startups_begin) 572 return 0; 573 if (startups >= options.max_startups) 574 return 1; 575 if (options.max_startups_rate == 100) 576 return 1; 577 578 p = 100 - options.max_startups_rate; 579 p *= startups - options.max_startups_begin; 580 p /= options.max_startups - options.max_startups_begin; 581 p += options.max_startups_rate; 582 r = arc4random_uniform(100); 583 584 debug_f("p %d, r %d", p, r); 585 return (r < p) ? 1 : 0; 586 } 587 588 /* 589 * Check whether connection should be accepted by MaxStartups or for penalty. 590 * Returns 0 if the connection is accepted. If the connection is refused, 591 * returns 1 and attempts to send notification to client. 592 * Logs when the MaxStartups condition is entered or exited, and periodically 593 * while in that state. 594 */ 595 static int 596 drop_connection(int sock, int startups, int notify_pipe) 597 { 598 static struct log_ratelimit_ctx ratelimit_maxstartups; 599 static struct log_ratelimit_ctx ratelimit_penalty; 600 static int init_done; 601 char *laddr, *raddr; 602 const char *reason = NULL, *subreason = NULL; 603 const char msg[] = "Not allowed at this time\r\n"; 604 struct log_ratelimit_ctx *rl = NULL; 605 int ratelimited; 606 u_int ndropped; 607 608 if (!init_done) { 609 init_done = 1; 610 log_ratelimit_init(&ratelimit_maxstartups, 4, 60, 20, 5*60); 611 log_ratelimit_init(&ratelimit_penalty, 8, 60, 30, 2*60); 612 } 613 614 /* PerSourcePenalties */ 615 if (!srclimit_penalty_check_allow(sock, &subreason)) { 616 reason = "PerSourcePenalties"; 617 rl = &ratelimit_penalty; 618 } else { 619 /* MaxStartups */ 620 if (!should_drop_connection(startups) && 621 srclimit_check_allow(sock, notify_pipe) == 1) 622 return 0; 623 reason = "Maxstartups"; 624 rl = &ratelimit_maxstartups; 625 } 626 627 laddr = get_local_ipaddr(sock); 628 raddr = get_peer_ipaddr(sock); 629 ratelimited = log_ratelimit(rl, time(NULL), NULL, &ndropped); 630 do_log2(ratelimited ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, 631 "drop connection #%d from [%s]:%d on [%s]:%d %s", 632 startups, 633 raddr, get_peer_port(sock), 634 laddr, get_local_port(sock), 635 subreason != NULL ? subreason : reason); 636 free(laddr); 637 free(raddr); 638 if (ndropped != 0) { 639 logit("%s logging rate-limited: additional %u connections " 640 "dropped", reason, ndropped); 641 } 642 643 /* best-effort notification to client */ 644 (void)write(sock, msg, sizeof(msg) - 1); 645 return 1; 646 } 647 648 __dead static void 649 usage(void) 650 { 651 fprintf(stderr, "%s, %s\n", SSH_VERSION, 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 *m = NULL, *keybuf = NULL, *hostkeys = NULL; 664 int r; 665 u_int i; 666 size_t len; 667 668 if ((m = sshbuf_new()) == NULL || 669 (keybuf = sshbuf_new()) == NULL || 670 (hostkeys = sshbuf_new()) == NULL) 671 fatal_f("sshbuf_new failed"); 672 673 /* pack hostkeys into a string. Empty key slots get empty strings */ 674 for (i = 0; i < options.num_host_key_files; i++) { 675 /* private key */ 676 sshbuf_reset(keybuf); 677 if (sensitive_data.host_keys[i] != NULL && 678 (r = sshkey_private_serialize(sensitive_data.host_keys[i], 679 keybuf)) != 0) 680 fatal_fr(r, "serialize hostkey private"); 681 if ((r = sshbuf_put_stringb(hostkeys, keybuf)) != 0) 682 fatal_fr(r, "compose hostkey private"); 683 /* public key */ 684 if (sensitive_data.host_pubkeys[i] != NULL) { 685 if ((r = sshkey_puts(sensitive_data.host_pubkeys[i], 686 hostkeys)) != 0) 687 fatal_fr(r, "compose hostkey public"); 688 } else { 689 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 690 fatal_fr(r, "compose hostkey empty public"); 691 } 692 /* cert */ 693 if (sensitive_data.host_certificates[i] != NULL) { 694 if ((r = sshkey_puts( 695 sensitive_data.host_certificates[i], 696 hostkeys)) != 0) 697 fatal_fr(r, "compose host cert"); 698 } else { 699 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0) 700 fatal_fr(r, "compose host cert empty"); 701 } 702 } 703 704 if ((r = sshbuf_put_u32(m, 0)) != 0 || 705 (r = sshbuf_put_u8(m, 0)) != 0 || 706 (r = sshbuf_put_stringb(m, hostkeys)) != 0) 707 fatal_fr(r, "compose message"); 708 if ((len = sshbuf_len(m)) < 5 || len > 0xffffffff) 709 fatal_f("bad length %zu", len); 710 POKE_U32(sshbuf_mutable_ptr(m), len - 4); 711 712 sshbuf_free(keybuf); 713 sshbuf_free(hostkeys); 714 return m; 715 } 716 717 static struct sshbuf * 718 pack_config(struct sshbuf *conf) 719 { 720 struct sshbuf *m = NULL, *inc = NULL; 721 struct include_item *item = NULL; 722 size_t len; 723 int r; 724 725 debug3_f("d config len %zu", sshbuf_len(conf)); 726 727 if ((m = sshbuf_new()) == NULL || 728 (inc = sshbuf_new()) == NULL) 729 fatal_f("sshbuf_new failed"); 730 731 /* pack includes into a string */ 732 TAILQ_FOREACH(item, &includes, entry) { 733 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 734 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 735 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 736 fatal_fr(r, "compose includes"); 737 } 738 739 if ((r = sshbuf_put_u32(m, 0)) != 0 || 740 (r = sshbuf_put_u8(m, 0)) != 0 || 741 (r = sshbuf_put_stringb(m, conf)) != 0 || 742 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 || 743 (r = sshbuf_put_stringb(m, inc)) != 0) 744 fatal_fr(r, "compose config"); 745 746 if ((len = sshbuf_len(m)) < 5 || len > 0xffffffff) 747 fatal_f("bad length %zu", len); 748 POKE_U32(sshbuf_mutable_ptr(m), len - 4); 749 750 sshbuf_free(inc); 751 752 debug3_f("done"); 753 return m; 754 } 755 756 /* 757 * Protocol from reexec master to child: 758 * uint32 size 759 * uint8 type (ignored) 760 * string configuration 761 * uint64 timing_secret 762 * string included_files[] { 763 * string selector 764 * string filename 765 * string contents 766 * } 767 * Second message 768 * uint32 size 769 * uint8 type (ignored) 770 * string host_keys[] { 771 * string private_key 772 * string public_key 773 * string certificate 774 * } 775 */ 776 /* 777 * This function is used only if inet_flag or debug_flag is set, 778 * otherwise the data is sent from the main poll loop. 779 * It sends the config from a child process back to the parent. 780 * The parent will read the config after exec. 781 */ 782 static void 783 send_rexec_state(int fd) 784 { 785 struct sshbuf *keys; 786 u_int mlen; 787 pid_t pid; 788 789 if ((pid = fork()) == -1) 790 fatal_f("fork failed: %s", strerror(errno)); 791 if (pid != 0) 792 return; 793 794 debug3_f("entering fd = %d config len %zu", fd, 795 sshbuf_len(config)); 796 797 mlen = sshbuf_len(config); 798 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(config), mlen) != mlen) 799 error_f("write: %s", strerror(errno)); 800 801 keys = pack_hostkeys(); 802 mlen = sshbuf_len(keys); 803 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(keys), mlen) != mlen) 804 error_f("write: %s", strerror(errno)); 805 806 sshbuf_free(keys); 807 debug3_f("done"); 808 exit(0); 809 } 810 811 /* 812 * Listen for TCP connections 813 */ 814 static void 815 listen_on_addrs(struct listenaddr *la) 816 { 817 int ret, listen_sock; 818 struct addrinfo *ai; 819 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 820 int socksize; 821 socklen_t socksizelen = sizeof(int); 822 823 for (ai = la->addrs; ai; ai = ai->ai_next) { 824 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 825 continue; 826 if (num_listen_socks >= MAX_LISTEN_SOCKS) 827 fatal("Too many listen sockets. " 828 "Enlarge MAX_LISTEN_SOCKS"); 829 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 830 ntop, sizeof(ntop), strport, sizeof(strport), 831 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 832 error("getnameinfo failed: %.100s", 833 ssh_gai_strerror(ret)); 834 continue; 835 } 836 /* Create socket for listening. */ 837 listen_sock = socket(ai->ai_family, ai->ai_socktype, 838 ai->ai_protocol); 839 if (listen_sock == -1) { 840 /* kernel may not support ipv6 */ 841 verbose("socket: %.100s", strerror(errno)); 842 continue; 843 } 844 if (set_nonblock(listen_sock) == -1) { 845 close(listen_sock); 846 continue; 847 } 848 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 849 verbose("socket: CLOEXEC: %s", strerror(errno)); 850 close(listen_sock); 851 continue; 852 } 853 /* Socket options */ 854 set_reuseaddr(listen_sock); 855 if (la->rdomain != NULL && 856 set_rdomain(listen_sock, la->rdomain) == -1) { 857 close(listen_sock); 858 continue; 859 } 860 861 debug("Bind to port %s on %s.", strport, ntop); 862 863 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 864 &socksize, &socksizelen); 865 debug("Server TCP RWIN socket size: %d", socksize); 866 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 867 868 /* Bind the socket to the desired port. */ 869 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 870 error("Bind to port %s on %s failed: %.200s.", 871 strport, ntop, strerror(errno)); 872 close(listen_sock); 873 continue; 874 } 875 listen_socks[num_listen_socks] = listen_sock; 876 num_listen_socks++; 877 878 /* Start listening on the port. */ 879 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 880 fatal("listen on [%s]:%s: %.100s", 881 ntop, strport, strerror(errno)); 882 logit("Server listening on %s port %s%s%s.", 883 ntop, strport, 884 la->rdomain == NULL ? "" : " rdomain ", 885 la->rdomain == NULL ? "" : la->rdomain); 886 } 887 } 888 889 static void 890 server_listen(void) 891 { 892 u_int i; 893 894 /* Initialise per-source limit tracking. */ 895 srclimit_init(options.max_startups, 896 options.per_source_max_startups, 897 options.per_source_masklen_ipv4, 898 options.per_source_masklen_ipv6, 899 &options.per_source_penalty, 900 options.per_source_penalty_exempt); 901 902 for (i = 0; i < options.num_listen_addrs; i++) { 903 listen_on_addrs(&options.listen_addrs[i]); 904 freeaddrinfo(options.listen_addrs[i].addrs); 905 free(options.listen_addrs[i].rdomain); 906 memset(&options.listen_addrs[i], 0, 907 sizeof(options.listen_addrs[i])); 908 } 909 free(options.listen_addrs); 910 options.listen_addrs = NULL; 911 options.num_listen_addrs = 0; 912 913 if (!num_listen_socks) 914 fatal("Cannot bind any address."); 915 } 916 917 /* 918 * The main TCP accept loop. Note that, for the non-debug case, returns 919 * from this function are in a forked subprocess. 920 */ 921 static void 922 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s, 923 int log_stderr) 924 { 925 struct pollfd *pfd = NULL; 926 int i, ret, npfd, r; 927 int oactive = -1, listening = 0, lameduck = 0; 928 int *startup_pollfd; 929 ssize_t len; 930 const u_char *ptr; 931 char c = 0; 932 struct sockaddr_storage from; 933 struct early_child *child; 934 struct sshbuf *buf; 935 socklen_t fromlen; 936 sigset_t nsigset, osigset; 937 938 /* setup fd set for accept */ 939 /* pipes connected to unauthenticated child sshd processes */ 940 child_alloc(); 941 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 942 943 /* 944 * Prepare signal mask that we use to block signals that might set 945 * received_sigterm/hup/chld/info, so that we are guaranteed 946 * to immediately wake up the ppoll if a signal is received after 947 * the flag is checked. 948 */ 949 sigemptyset(&nsigset); 950 sigaddset(&nsigset, SIGHUP); 951 sigaddset(&nsigset, SIGCHLD); 952 sigaddset(&nsigset, SIGINFO); 953 sigaddset(&nsigset, SIGTERM); 954 sigaddset(&nsigset, SIGQUIT); 955 956 /* sized for worst-case */ 957 pfd = xcalloc(num_listen_socks + options.max_startups, 958 sizeof(struct pollfd)); 959 960 /* 961 * Stay listening for connections until the system crashes or 962 * the daemon is killed with a signal. 963 */ 964 for (;;) { 965 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 966 if (received_sigterm) { 967 logit("Received signal %d; terminating.", 968 (int) received_sigterm); 969 close_listen_socks(); 970 if (options.pid_file != NULL) 971 unlink(options.pid_file); 972 exit(received_sigterm == SIGTERM ? 0 : 255); 973 } 974 if (received_sigchld) { 975 child_reap_all_exited(); 976 received_sigchld = 0; 977 } 978 if (received_siginfo) { 979 show_info(); 980 received_siginfo = 0; 981 } 982 if (oactive != children_active) { 983 setproctitle("%s [listener] %d of %d-%d startups", 984 listener_proctitle, children_active, 985 options.max_startups_begin, options.max_startups); 986 oactive = children_active; 987 } 988 if (received_sighup) { 989 if (!lameduck) { 990 debug("Received SIGHUP; waiting for children"); 991 close_listen_socks(); 992 lameduck = 1; 993 } 994 if (listening <= 0) { 995 sigprocmask(SIG_SETMASK, &osigset, NULL); 996 sighup_restart(); 997 } 998 } 999 1000 for (i = 0; i < num_listen_socks; i++) { 1001 pfd[i].fd = listen_socks[i]; 1002 pfd[i].events = POLLIN; 1003 } 1004 npfd = num_listen_socks; 1005 for (i = 0; i < options.max_startups; i++) { 1006 startup_pollfd[i] = -1; 1007 if (children[i].pipefd != -1) { 1008 pfd[npfd].fd = children[i].pipefd; 1009 pfd[npfd].events = POLLIN; 1010 if (children[i].config != NULL || 1011 children[i].keys != NULL) 1012 pfd[npfd].events |= POLLOUT; 1013 startup_pollfd[i] = npfd++; 1014 } 1015 } 1016 1017 /* Wait until a connection arrives or a child exits. */ 1018 ret = ppoll(pfd, npfd, NULL, &osigset); 1019 if (ret == -1 && errno != EINTR) { 1020 error("ppoll: %.100s", strerror(errno)); 1021 if (errno == EINVAL) 1022 cleanup_exit(1); /* can't recover */ 1023 } 1024 sigprocmask(SIG_SETMASK, &osigset, NULL); 1025 if (ret == -1) 1026 continue; 1027 1028 for (i = 0; i < options.max_startups; i++) { 1029 if (children[i].pipefd == -1 || 1030 startup_pollfd[i] == -1 || 1031 !(pfd[startup_pollfd[i]].revents & POLLOUT)) 1032 continue; 1033 if (children[i].config) 1034 buf = children[i].config; 1035 else if (children[i].keys) 1036 buf = children[i].keys; 1037 else { 1038 error_f("no buffer to send"); 1039 continue; 1040 } 1041 ptr = sshbuf_ptr(buf); 1042 len = sshbuf_len(buf); 1043 ret = write(children[i].pipefd, ptr, len); 1044 if (ret == -1 && (errno == EINTR || errno == EAGAIN)) 1045 continue; 1046 if (ret <= 0) { 1047 if (children[i].early) 1048 listening--; 1049 child_close(&(children[i]), 0, 0); 1050 continue; 1051 } 1052 if (ret == len) { 1053 /* finished sending buffer */ 1054 sshbuf_free(buf); 1055 if (children[i].config == buf) { 1056 /* sent config, now send keys */ 1057 children[i].config = NULL; 1058 children[i].keys = pack_hostkeys(); 1059 } else if (children[i].keys == buf) { 1060 /* sent both config and keys */ 1061 children[i].keys = NULL; 1062 } else { 1063 fatal("config buf not set"); 1064 } 1065 1066 } else { 1067 if ((r = sshbuf_consume(buf, ret)) != 0) 1068 fatal_fr(r, "config buf inconsistent"); 1069 } 1070 } 1071 for (i = 0; i < options.max_startups; i++) { 1072 if (children[i].pipefd == -1 || 1073 startup_pollfd[i] == -1 || 1074 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 1075 continue; 1076 switch (read(children[i].pipefd, &c, sizeof(c))) { 1077 case -1: 1078 if (errno == EINTR || errno == EAGAIN) 1079 continue; 1080 if (errno != EPIPE) { 1081 error_f("startup pipe %d (fd=%d): " 1082 "read %s", i, children[i].pipefd, 1083 strerror(errno)); 1084 } 1085 /* FALLTHROUGH */ 1086 case 0: 1087 /* child closed pipe */ 1088 if (children[i].early) 1089 listening--; 1090 debug3_f("child %lu for %s closed pipe", 1091 (long)children[i].pid, children[i].id); 1092 child_close(&(children[i]), 0, 0); 1093 break; 1094 case 1: 1095 if (children[i].config) { 1096 error_f("startup pipe %d (fd=%d)" 1097 " early read", 1098 i, children[i].pipefd); 1099 goto problem_child; 1100 } 1101 if (children[i].early && c == '\0') { 1102 /* child has finished preliminaries */ 1103 listening--; 1104 children[i].early = 0; 1105 debug2_f("child %lu for %s received " 1106 "config", (long)children[i].pid, 1107 children[i].id); 1108 } else if (!children[i].early && c == '\001') { 1109 /* child has completed auth */ 1110 debug2_f("child %lu for %s auth done", 1111 (long)children[i].pid, 1112 children[i].id); 1113 child_close(&(children[i]), 1, 0); 1114 } else { 1115 error_f("unexpected message 0x%02x " 1116 "child %ld for %s in state %d", 1117 (int)c, (long)children[i].pid, 1118 children[i].id, children[i].early); 1119 problem_child: 1120 if (children[i].early) 1121 listening--; 1122 if (children[i].pid > 0) 1123 kill(children[i].pid, SIGTERM); 1124 child_close(&(children[i]), 0, 0); 1125 } 1126 break; 1127 } 1128 } 1129 for (i = 0; i < num_listen_socks; i++) { 1130 if (!(pfd[i].revents & POLLIN)) 1131 continue; 1132 fromlen = sizeof(from); 1133 *newsock = accept(listen_socks[i], 1134 (struct sockaddr *)&from, &fromlen); 1135 if (*newsock == -1) { 1136 if (errno != EINTR && errno != EWOULDBLOCK && 1137 errno != ECONNABORTED) 1138 error("accept: %.100s", 1139 strerror(errno)); 1140 if (errno == EMFILE || errno == ENFILE) 1141 usleep(100 * 1000); 1142 continue; 1143 } 1144 if (unset_nonblock(*newsock) == -1) { 1145 close(*newsock); 1146 continue; 1147 } 1148 if (socketpair(AF_UNIX, 1149 SOCK_STREAM, 0, config_s) == -1) { 1150 error("reexec socketpair: %s", 1151 strerror(errno)); 1152 close(*newsock); 1153 continue; 1154 } 1155 if (drop_connection(*newsock, 1156 children_active, config_s[0])) { 1157 close(*newsock); 1158 close(config_s[0]); 1159 close(config_s[1]); 1160 continue; 1161 } 1162 1163 /* 1164 * Got connection. Fork a child to handle it, unless 1165 * we are in debugging mode. 1166 */ 1167 if (debug_flag) { 1168 /* 1169 * In debugging mode. Close the listening 1170 * socket, and start processing the 1171 * connection without forking. 1172 */ 1173 debug("Server will not fork when running in debugging mode."); 1174 close_listen_socks(); 1175 *sock_in = *newsock; 1176 *sock_out = *newsock; 1177 send_rexec_state(config_s[0]); 1178 close(config_s[0]); 1179 free(pfd); 1180 free(startup_pollfd); 1181 return; 1182 } 1183 1184 /* 1185 * Normal production daemon. Fork, and have 1186 * the child process the connection. The 1187 * parent continues listening. 1188 */ 1189 set_nonblock(config_s[0]); 1190 listening++; 1191 child = child_register(config_s[0], *newsock); 1192 if ((child->pid = fork()) == 0) { 1193 /* 1194 * Child. Close the listening and 1195 * max_startup sockets. Start using 1196 * the accepted socket. Reinitialize 1197 * logging (since our pid has changed). 1198 * We return from this function to handle 1199 * the connection. 1200 */ 1201 close_startup_pipes(); 1202 close_listen_socks(); 1203 *sock_in = *newsock; 1204 *sock_out = *newsock; 1205 log_init(__progname, 1206 options.log_level, 1207 options.log_facility, 1208 log_stderr); 1209 close(config_s[0]); 1210 free(pfd); 1211 free(startup_pollfd); 1212 return; 1213 } 1214 1215 /* Parent. Stay in the loop. */ 1216 if (child->pid == -1) 1217 error("fork: %.100s", strerror(errno)); 1218 else 1219 debug("Forked child %ld.", (long)child->pid); 1220 1221 close(config_s[1]); 1222 close(*newsock); 1223 } 1224 } 1225 } 1226 1227 static void 1228 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1229 struct sshkey *key) 1230 { 1231 static struct ssh_digest_ctx *ctx; 1232 u_char *hash; 1233 size_t len; 1234 struct sshbuf *buf; 1235 int r; 1236 1237 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1238 fatal_f("ssh_digest_start"); 1239 if (key == NULL) { /* finalize */ 1240 /* add server config in case we are using agent for host keys */ 1241 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1242 sshbuf_len(server_cfg)) != 0) 1243 fatal_f("ssh_digest_update"); 1244 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1245 hash = xmalloc(len); 1246 if (ssh_digest_final(ctx, hash, len) != 0) 1247 fatal_f("ssh_digest_final"); 1248 options.timing_secret = PEEK_U64(hash); 1249 freezero(hash, len); 1250 ssh_digest_free(ctx); 1251 ctx = NULL; 1252 return; 1253 } 1254 if ((buf = sshbuf_new()) == NULL) 1255 fatal_f("could not allocate buffer"); 1256 if ((r = sshkey_private_serialize(key, buf)) != 0) 1257 fatal_fr(r, "encode %s key", sshkey_ssh_name(key)); 1258 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1259 fatal_f("ssh_digest_update"); 1260 sshbuf_reset(buf); 1261 sshbuf_free(buf); 1262 } 1263 1264 static char * 1265 prepare_proctitle(int ac, char **av) 1266 { 1267 char *ret = NULL; 1268 int i; 1269 1270 for (i = 0; i < ac; i++) 1271 xextendf(&ret, " ", "%s", av[i]); 1272 return ret; 1273 } 1274 1275 __dead static void 1276 print_config(struct connection_info *connection_info) 1277 { 1278 connection_info->test = 1; 1279 parse_server_match_config(&options, &includes, connection_info); 1280 dump_config(&options); 1281 exit(0); 1282 } 1283 1284 /* 1285 * Main program for the daemon. 1286 */ 1287 int 1288 main(int ac, char **av) 1289 { 1290 extern char *optarg; 1291 extern int optind; 1292 int log_stderr = 0, inetd_flag = 0, test_flag = 0, no_daemon_flag = 0; 1293 const char *config_file_name = _PATH_SERVER_CONFIG_FILE; 1294 int r, opt, do_dump_cfg = 0, keytype, already_daemon, have_agent = 0; 1295 int sock_in = -1, sock_out = -1, newsock = -1, rexec_argc = 0; 1296 int devnull, config_s[2] = { -1 , -1 }, have_connection_info = 0; 1297 char *args, *fp, *line, *logfile = NULL, **rexec_argv = NULL; 1298 struct stat sb; 1299 u_int i, j; 1300 mode_t new_umask; 1301 struct sshkey *key; 1302 struct sshkey *pubkey; 1303 struct utsname utsname; 1304 struct connection_info connection_info; 1305 sigset_t sigmask; 1306 1307 memset(&connection_info, 0, sizeof(connection_info)); 1308 1309 sigemptyset(&sigmask); 1310 sigprocmask(SIG_SETMASK, &sigmask, NULL); 1311 1312 /* Save argv. */ 1313 saved_argv = av; 1314 rexec_argc = ac; 1315 1316 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1317 sanitise_stdfd(); 1318 1319 /* Initialize configuration options to their default values. */ 1320 initialize_server_options(&options); 1321 1322 /* Parse command-line arguments. */ 1323 args = argv_assemble(ac, av); /* logged later */ 1324 while ((opt = getopt(ac, av, 1325 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) { 1326 switch (opt) { 1327 case '4': 1328 options.address_family = AF_INET; 1329 break; 1330 case '6': 1331 options.address_family = AF_INET6; 1332 break; 1333 case 'f': 1334 config_file_name = optarg; 1335 break; 1336 case 'c': 1337 servconf_add_hostcert("[command-line]", 0, 1338 &options, optarg); 1339 break; 1340 case 'd': 1341 if (debug_flag == 0) { 1342 debug_flag = 1; 1343 options.log_level = SYSLOG_LEVEL_DEBUG1; 1344 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1345 options.log_level++; 1346 break; 1347 case 'D': 1348 no_daemon_flag = 1; 1349 break; 1350 case 'G': 1351 do_dump_cfg = 1; 1352 break; 1353 case 'E': 1354 logfile = optarg; 1355 /* FALLTHROUGH */ 1356 case 'e': 1357 log_stderr = 1; 1358 break; 1359 case 'i': 1360 inetd_flag = 1; 1361 break; 1362 case 'r': 1363 logit("-r option is deprecated"); 1364 break; 1365 case 'R': 1366 fatal("-R not supported here"); 1367 break; 1368 case 'Q': 1369 /* ignored */ 1370 break; 1371 case 'q': 1372 options.log_level = SYSLOG_LEVEL_QUIET; 1373 break; 1374 case 'b': 1375 /* protocol 1, ignored */ 1376 break; 1377 case 'p': 1378 options.ports_from_cmdline = 1; 1379 if (options.num_ports >= MAX_PORTS) { 1380 fprintf(stderr, "too many ports.\n"); 1381 exit(1); 1382 } 1383 options.ports[options.num_ports++] = a2port(optarg); 1384 if (options.ports[options.num_ports-1] <= 0) { 1385 fprintf(stderr, "Bad port number.\n"); 1386 exit(1); 1387 } 1388 break; 1389 case 'g': 1390 if ((options.login_grace_time = convtime(optarg)) == -1) { 1391 fprintf(stderr, "Invalid login grace time.\n"); 1392 exit(1); 1393 } 1394 break; 1395 case 'k': 1396 /* protocol 1, ignored */ 1397 break; 1398 case 'h': 1399 servconf_add_hostkey("[command-line]", 0, 1400 &options, optarg, 1); 1401 break; 1402 case 't': 1403 test_flag = 1; 1404 break; 1405 case 'T': 1406 test_flag = 2; 1407 break; 1408 case 'C': 1409 if (parse_server_match_testspec(&connection_info, 1410 optarg) == -1) 1411 exit(1); 1412 have_connection_info = 1; 1413 break; 1414 case 'u': 1415 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1416 if (utmp_len > HOST_NAME_MAX+1) { 1417 fprintf(stderr, "Invalid utmp length.\n"); 1418 exit(1); 1419 } 1420 break; 1421 case 'o': 1422 line = xstrdup(optarg); 1423 if (process_server_config_line(&options, line, 1424 "command-line", 0, NULL, NULL, &includes) != 0) 1425 exit(1); 1426 free(line); 1427 break; 1428 case 'V': 1429 fprintf(stderr, "%s, %s\n", 1430 SSH_VERSION, SSH_OPENSSL_VERSION); 1431 exit(0); 1432 default: 1433 usage(); 1434 break; 1435 } 1436 } 1437 if (!test_flag && !inetd_flag && !do_dump_cfg && !path_absolute(av[0])) 1438 fatal("sshd requires execution with an absolute path"); 1439 1440 closefrom(STDERR_FILENO + 1); 1441 1442 /* Reserve fds we'll need later for reexec things */ 1443 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) 1444 fatal("open %s: %s", _PATH_DEVNULL, strerror(errno)); 1445 while (devnull < REEXEC_MIN_FREE_FD) { 1446 if ((devnull = dup(devnull)) == -1) 1447 fatal("dup %s: %s", _PATH_DEVNULL, strerror(errno)); 1448 } 1449 1450 /* If requested, redirect the logs to the specified logfile. */ 1451 if (logfile != NULL) { 1452 char *cp, pid_s[32]; 1453 1454 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid()); 1455 cp = percent_expand(logfile, 1456 "p", pid_s, 1457 "P", "sshd", 1458 (char *)NULL); 1459 log_redirect_stderr_to(cp); 1460 free(cp); 1461 } 1462 1463 /* 1464 * Force logging to stderr until we have loaded the private host 1465 * key (unless started from inetd) 1466 */ 1467 log_init(__progname, 1468 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1469 SYSLOG_LEVEL_INFO : options.log_level, 1470 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1471 SYSLOG_FACILITY_AUTH : options.log_facility, 1472 log_stderr || !inetd_flag || debug_flag); 1473 1474 sensitive_data.have_ssh2_key = 0; 1475 1476 /* 1477 * If we're not doing an extended test do not silently ignore connection 1478 * test params. 1479 */ 1480 if (test_flag < 2 && have_connection_info) 1481 fatal("Config test connection parameter (-C) provided without " 1482 "test mode (-T)"); 1483 1484 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1485 if (uname(&utsname) != 0) { 1486 memset(&utsname, 0, sizeof(utsname)); 1487 strlcpy(utsname.sysname, "UNKNOWN", sizeof(utsname.sysname)); 1488 } 1489 debug3("Running on %s %s %s %s", utsname.sysname, utsname.release, 1490 utsname.version, utsname.machine); 1491 debug3("Started with: %s", args); 1492 free(args); 1493 1494 /* Fetch our configuration */ 1495 if ((cfg = sshbuf_new()) == NULL) 1496 fatal("sshbuf_new config failed"); 1497 if (strcasecmp(config_file_name, "none") != 0) 1498 load_server_config(config_file_name, cfg); 1499 1500 parse_server_config(&options, config_file_name, cfg, 1501 &includes, NULL, 0); 1502 1503 /* Fill in default values for those options not explicitly set. */ 1504 fill_default_server_options(&options); 1505 1506 /* Check that options are sensible */ 1507 if (options.authorized_keys_command_user == NULL && 1508 (options.authorized_keys_command != NULL && 1509 strcasecmp(options.authorized_keys_command, "none") != 0)) 1510 fatal("AuthorizedKeysCommand set without " 1511 "AuthorizedKeysCommandUser"); 1512 if (options.authorized_principals_command_user == NULL && 1513 (options.authorized_principals_command != NULL && 1514 strcasecmp(options.authorized_principals_command, "none") != 0)) 1515 fatal("AuthorizedPrincipalsCommand set without " 1516 "AuthorizedPrincipalsCommandUser"); 1517 1518 /* 1519 * Check whether there is any path through configured auth methods. 1520 * Unfortunately it is not possible to verify this generally before 1521 * daemonisation in the presence of Match blocks, but this catches 1522 * and warns for trivial misconfigurations that could break login. 1523 */ 1524 if (options.num_auth_methods != 0) { 1525 for (i = 0; i < options.num_auth_methods; i++) { 1526 if (auth2_methods_valid(options.auth_methods[i], 1527 1) == 0) 1528 break; 1529 } 1530 if (i >= options.num_auth_methods) 1531 fatal("AuthenticationMethods cannot be satisfied by " 1532 "enabled authentication methods"); 1533 } 1534 1535 /* Check that there are no remaining arguments. */ 1536 if (optind < ac) { 1537 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1538 exit(1); 1539 } 1540 1541 if (do_dump_cfg) 1542 print_config(&connection_info); 1543 1544 /* load host keys */ 1545 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1546 sizeof(struct sshkey *)); 1547 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1548 sizeof(struct sshkey *)); 1549 1550 if (options.host_key_agent) { 1551 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1552 setenv(SSH_AUTHSOCKET_ENV_NAME, 1553 options.host_key_agent, 1); 1554 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1555 have_agent = 1; 1556 else 1557 error_r(r, "Could not connect to agent \"%s\"", 1558 options.host_key_agent); 1559 } 1560 1561 for (i = 0; i < options.num_host_key_files; i++) { 1562 int ll = options.host_key_file_userprovided[i] ? 1563 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1564 1565 if (options.host_key_files[i] == NULL) 1566 continue; 1567 if ((r = sshkey_load_private(options.host_key_files[i], "", 1568 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1569 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1570 options.host_key_files[i]); 1571 if (sshkey_is_sk(key) && 1572 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1573 debug("host key %s requires user presence, ignoring", 1574 options.host_key_files[i]); 1575 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1576 } 1577 if (r == 0 && key != NULL && 1578 (r = sshkey_shield_private(key)) != 0) { 1579 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1580 options.host_key_files[i]); 1581 sshkey_free(key); 1582 key = NULL; 1583 } 1584 if ((r = sshkey_load_public(options.host_key_files[i], 1585 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1586 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1587 options.host_key_files[i]); 1588 if (pubkey != NULL && key != NULL) { 1589 if (!sshkey_equal(pubkey, key)) { 1590 error("Public key for %s does not match " 1591 "private key", options.host_key_files[i]); 1592 sshkey_free(pubkey); 1593 pubkey = NULL; 1594 } 1595 } 1596 if (pubkey == NULL && key != NULL) { 1597 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1598 fatal_r(r, "Could not demote key: \"%s\"", 1599 options.host_key_files[i]); 1600 } 1601 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1602 options.required_rsa_size)) != 0) { 1603 error_fr(r, "Host key %s", options.host_key_files[i]); 1604 sshkey_free(pubkey); 1605 sshkey_free(key); 1606 continue; 1607 } 1608 sensitive_data.host_keys[i] = key; 1609 sensitive_data.host_pubkeys[i] = pubkey; 1610 1611 if (key == NULL && pubkey != NULL && have_agent) { 1612 debug("will rely on agent for hostkey %s", 1613 options.host_key_files[i]); 1614 keytype = pubkey->type; 1615 } else if (key != NULL) { 1616 keytype = key->type; 1617 accumulate_host_timing_secret(cfg, key); 1618 } else { 1619 do_log2(ll, "Unable to load host key: %s", 1620 options.host_key_files[i]); 1621 sensitive_data.host_keys[i] = NULL; 1622 sensitive_data.host_pubkeys[i] = NULL; 1623 continue; 1624 } 1625 1626 switch (keytype) { 1627 case KEY_RSA: 1628 case KEY_ECDSA: 1629 case KEY_ED25519: 1630 case KEY_ECDSA_SK: 1631 case KEY_ED25519_SK: 1632 if (have_agent || key != NULL) 1633 sensitive_data.have_ssh2_key = 1; 1634 break; 1635 } 1636 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1637 SSH_FP_DEFAULT)) == NULL) 1638 fatal("sshkey_fingerprint failed"); 1639 debug("%s host key #%d: %s %s", 1640 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1641 free(fp); 1642 } 1643 accumulate_host_timing_secret(cfg, NULL); 1644 if (!sensitive_data.have_ssh2_key) { 1645 logit("sshd: no hostkeys available -- exiting."); 1646 exit(1); 1647 } 1648 1649 /* 1650 * Load certificates. They are stored in an array at identical 1651 * indices to the public keys that they relate to. 1652 */ 1653 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1654 sizeof(struct sshkey *)); 1655 for (i = 0; i < options.num_host_key_files; i++) 1656 sensitive_data.host_certificates[i] = NULL; 1657 1658 for (i = 0; i < options.num_host_cert_files; i++) { 1659 if (options.host_cert_files[i] == NULL) 1660 continue; 1661 if ((r = sshkey_load_public(options.host_cert_files[i], 1662 &key, NULL)) != 0) { 1663 error_r(r, "Could not load host certificate \"%s\"", 1664 options.host_cert_files[i]); 1665 continue; 1666 } 1667 if (!sshkey_is_cert(key)) { 1668 error("Certificate file is not a certificate: %s", 1669 options.host_cert_files[i]); 1670 sshkey_free(key); 1671 continue; 1672 } 1673 /* Find matching private key */ 1674 for (j = 0; j < options.num_host_key_files; j++) { 1675 if (sshkey_equal_public(key, 1676 sensitive_data.host_pubkeys[j])) { 1677 sensitive_data.host_certificates[j] = key; 1678 break; 1679 } 1680 } 1681 if (j >= options.num_host_key_files) { 1682 error("No matching private key for certificate: %s", 1683 options.host_cert_files[i]); 1684 sshkey_free(key); 1685 continue; 1686 } 1687 sensitive_data.host_certificates[j] = key; 1688 debug("host certificate: #%u type %d %s", j, key->type, 1689 sshkey_type(key)); 1690 } 1691 1692 /* Ensure privsep directory is correctly configured. */ 1693 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1694 fatal("Privilege separation user %s does not exist", 1695 SSH_PRIVSEP_USER); 1696 endpwent(); 1697 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &sb) == -1) || 1698 (S_ISDIR(sb.st_mode) == 0)) 1699 fatal("Missing privilege separation directory: %s", 1700 _PATH_PRIVSEP_CHROOT_DIR); 1701 if (sb.st_uid != 0 || (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1702 fatal("%s must be owned by root and not group or " 1703 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1704 1705 if (test_flag > 1) 1706 print_config(&connection_info); 1707 1708 config = pack_config(cfg); 1709 if (sshbuf_len(config) > MONITOR_MAX_CFGLEN) { 1710 fatal("Configuration file is too large (have %zu, max %d)", 1711 sshbuf_len(config), MONITOR_MAX_CFGLEN); 1712 } 1713 1714 /* Configuration looks good, so exit if in test mode. */ 1715 if (test_flag) 1716 exit(0); 1717 1718 /* Prepare arguments for sshd-session */ 1719 if (rexec_argc < 0) 1720 fatal("rexec_argc %d < 0", rexec_argc); 1721 rexec_argv = xcalloc(rexec_argc + 3, sizeof(char *)); 1722 /* Point to the sshd-session binary instead of sshd */ 1723 rexec_argv[0] = options.sshd_session_path; 1724 for (i = 1; i < (u_int)rexec_argc; i++) { 1725 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1726 rexec_argv[i] = saved_argv[i]; 1727 } 1728 rexec_argv[rexec_argc++] = __UNCONST("-R"); 1729 rexec_argv[rexec_argc] = NULL; 1730 if (stat(rexec_argv[0], &sb) != 0 || !(sb.st_mode & (S_IXOTH|S_IXUSR))) 1731 fatal("%s does not exist or is not executable", rexec_argv[0]); 1732 debug3("using %s for re-exec", rexec_argv[0]); 1733 1734 /* Ensure that the privsep binary exists now too. */ 1735 if (stat(options.sshd_auth_path, &sb) != 0 || 1736 !(sb.st_mode & (S_IXOTH|S_IXUSR))) { 1737 fatal("%s does not exist or is not executable", 1738 options.sshd_auth_path); 1739 } 1740 1741 listener_proctitle = prepare_proctitle(ac, av); 1742 1743 /* Ensure that umask disallows at least group and world write */ 1744 new_umask = umask(0077) | 0022; 1745 (void) umask(new_umask); 1746 1747 /* Initialize the log (it is reinitialized below in case we forked). */ 1748 if (debug_flag && !inetd_flag) 1749 log_stderr = 1; 1750 log_init(__progname, options.log_level, 1751 options.log_facility, log_stderr); 1752 for (i = 0; i < options.num_log_verbose; i++) 1753 log_verbose_add(options.log_verbose[i]); 1754 1755 /* 1756 * If not in debugging mode, not started from inetd and not already 1757 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1758 * terminal, and fork. The original process exits. 1759 */ 1760 already_daemon = daemonized(); 1761 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1762 1763 if (daemon(0, 0) == -1) 1764 fatal("daemon() failed: %.200s", strerror(errno)); 1765 1766 disconnect_controlling_tty(); 1767 } 1768 /* Reinitialize the log (because of the fork above). */ 1769 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1770 1771 /* 1772 * Chdir to the root directory so that the current disk can be 1773 * unmounted if desired. 1774 */ 1775 if (chdir("/") == -1) 1776 error("chdir(\"/\"): %s", strerror(errno)); 1777 1778 /* ignore SIGPIPE */ 1779 ssh_signal(SIGPIPE, SIG_IGN); 1780 1781 /* Get a connection, either from inetd or a listening TCP socket */ 1782 if (inetd_flag) { 1783 /* Send configuration to ancestor sshd-session process */ 1784 if (socketpair(AF_UNIX, SOCK_STREAM, 0, config_s) == -1) 1785 fatal("socketpair: %s", strerror(errno)); 1786 send_rexec_state(config_s[0]); 1787 close(config_s[0]); 1788 } else { 1789 server_listen(); 1790 1791 ssh_signal(SIGHUP, sighup_handler); 1792 ssh_signal(SIGCHLD, main_sigchld_handler); 1793 ssh_signal(SIGTERM, sigterm_handler); 1794 ssh_signal(SIGQUIT, sigterm_handler); 1795 ssh_signal(SIGINFO, siginfo_handler); 1796 1797 /* 1798 * Write out the pid file after the sigterm handler 1799 * is setup and the listen sockets are bound 1800 */ 1801 if (options.pid_file != NULL && !debug_flag) { 1802 FILE *f = fopen(options.pid_file, "w"); 1803 1804 if (f == NULL) { 1805 error("Couldn't create pid file \"%s\": %s", 1806 options.pid_file, strerror(errno)); 1807 } else { 1808 fprintf(f, "%ld\n", (long) getpid()); 1809 fclose(f); 1810 } 1811 } 1812 1813 /* Accept a connection and return in a forked child */ 1814 server_accept_loop(&sock_in, &sock_out, 1815 &newsock, config_s, log_stderr); 1816 } 1817 1818 /* This is the child processing a new connection. */ 1819 setproctitle("%s", "[accepted]"); 1820 1821 /* 1822 * Create a new session and process group since the 4.4BSD 1823 * setlogin() affects the entire process group. We don't 1824 * want the child to be able to affect the parent. 1825 */ 1826 if (!debug_flag && !inetd_flag && setsid() == -1) 1827 error("setsid: %.100s", strerror(errno)); 1828 1829 debug("rexec start in %d out %d newsock %d config_s %d/%d", 1830 sock_in, sock_out, newsock, config_s[0], config_s[1]); 1831 if (!inetd_flag) { 1832 if (dup2(newsock, STDIN_FILENO) == -1) 1833 fatal("dup2 stdin: %s", strerror(errno)); 1834 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1) 1835 fatal("dup2 stdout: %s", strerror(errno)); 1836 if (newsock > STDOUT_FILENO) 1837 close(newsock); 1838 } 1839 if (config_s[1] != REEXEC_CONFIG_PASS_FD) { 1840 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1) 1841 fatal("dup2 config_s: %s", strerror(errno)); 1842 close(config_s[1]); 1843 } 1844 log_redirect_stderr_to(NULL); 1845 closefrom(REEXEC_MIN_FREE_FD); 1846 1847 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1848 execv(rexec_argv[0], rexec_argv); 1849 1850 fatal("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1851 } 1852 1853 /* server specific fatal cleanup */ 1854 void 1855 cleanup_exit(int i) 1856 { 1857 _exit(i); 1858 } 1859
Indexes created Wed Jul 29 00:25:28 UTC 2026