crypto/openssh/sshd.c

   1 /* $OpenBSD: sshd.c,v 1.591 2022/09/17 10:34:29 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This program is the ssh daemon.  It listens for connections from clients,
   7  * and performs authentication, executes use commands or shell, and forwards
   8  * information to/from the application to the user client over an encrypted
   9  * connection.  This can also handle forwarding of X11, TCP/IP, and
  10  * authentication agent connections.
  11  *
  12  * As far as I am concerned, the code I have written for this software
  13  * can be used freely for any purpose.  Any derived versions of this
  14  * software must be clearly marked as such, and if the derived work is
  15  * incompatible with the protocol description in the RFC file, it must be
  16  * called by a name other than "ssh" or "Secure Shell".
  17  *
  18  * SSH2 implementation:
  19  * Privilege Separation:
  20  *
  21  * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  22  * Copyright (c) 2002 Niels Provos.  All rights reserved.
  23  *
  24  * Redistribution and use in source and binary forms, with or without
  25  * modification, are permitted provided that the following conditions
  26  * are met:
  27  * 1. Redistributions of source code must retain the above copyright
  28  *    notice, this list of conditions and the following disclaimer.
  29  * 2. Redistributions in binary form must reproduce the above copyright
  30  *    notice, this list of conditions and the following disclaimer in the
  31  *    documentation and/or other materials provided with the distribution.
  32  *
  33  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  34  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  35  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  36  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  37  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  38  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  39  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  40  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  41  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  42  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  43  */
  44
  45 #include "includes.h"
  46
  47 #include <sys/types.h>
  48 #include <sys/ioctl.h>
  49 #include <sys/mman.h>
  50 #include <sys/socket.h>
  51 #ifdef HAVE_SYS_STAT_H
  52 # include <sys/stat.h>
  53 #endif
  54 #ifdef HAVE_SYS_TIME_H
  55 # include <sys/time.h>
  56 #endif
  57 #include "openbsd-compat/sys-tree.h"
  58 #include "openbsd-compat/sys-queue.h"
  59 #include <sys/wait.h>
  60
  61 #include <errno.h>
  62 #include <fcntl.h>
  63 #include <netdb.h>
  64 #ifdef HAVE_PATHS_H
  65 #include <paths.h>
  66 #endif
  67 #include <grp.h>
  68 #ifdef HAVE_POLL_H
  69 #include <poll.h>
  70 #endif
  71 #include <pwd.h>
  72 #include <signal.h>
  73 #include <stdarg.h>
  74 #include <stdio.h>
  75 #include <stdlib.h>
  76 #include <string.h>
  77 #include <unistd.h>
  78 #include <limits.h>
  79
  80 #ifdef WITH_OPENSSL
  81 #include <openssl/dh.h>
  82 #include <openssl/bn.h>
  83 #include <openssl/rand.h>
  84 #include "openbsd-compat/openssl-compat.h"
  85 #endif
  86
  87 #ifdef HAVE_SECUREWARE
  88 #include <sys/security.h>
  89 #include <prot.h>
  90 #endif
  91
  92 #ifdef __FreeBSD__
  93 #include <resolv.h>
  94 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
  95 #include <gssapi/gssapi.h>
  96 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H)
  97 #include <gssapi.h>
  98 #endif
  99 #endif
 100
 101 #include "xmalloc.h"
 102 #include "ssh.h"
 103 #include "ssh2.h"
 104 #include "sshpty.h"
 105 #include "packet.h"
 106 #include "log.h"
 107 #include "sshbuf.h"
 108 #include "misc.h"
 109 #include "match.h"
 110 #include "servconf.h"
 111 #include "uidswap.h"
 112 #include "compat.h"
 113 #include "cipher.h"
 114 #include "digest.h"
 115 #include "sshkey.h"
 116 #include "kex.h"
 117 #include "myproposal.h"
 118 #include "authfile.h"
 119 #include "pathnames.h"
 120 #include "atomicio.h"
 121 #include "canohost.h"
 122 #include "hostfile.h"
 123 #include "auth.h"
 124 #include "authfd.h"
 125 #include "msg.h"
 126 #include "dispatch.h"
 127 #include "channels.h"
 128 #include "session.h"
 129 #include "monitor.h"
 130 #ifdef GSSAPI
 131 #include "ssh-gss.h"
 132 #endif
 133 #include "monitor_wrap.h"
 134 #include "ssh-sandbox.h"
 135 #include "auth-options.h"
 136 #include "version.h"
 137 #include "ssherr.h"
 138 #include "sk-api.h"
 139 #include "srclimit.h"
 140 #include "dh.h"
 141 #include "blacklist_client.h"
 142
 143 #ifdef LIBWRAP
 144 #include <tcpd.h>
 145 #include <syslog.h>
 146 extern int allow_severity;
 147 extern int deny_severity;
 148 #endif /* LIBWRAP */
 149
 150 /* Re-exec fds */
 151 #define REEXEC_DEVCRYPTO_RESERVED_FD    (STDERR_FILENO + 1)
 152 #define REEXEC_STARTUP_PIPE_FD          (STDERR_FILENO + 2)
 153 #define REEXEC_CONFIG_PASS_FD           (STDERR_FILENO + 3)
 154 #define REEXEC_MIN_FREE_FD              (STDERR_FILENO + 4)
 155
 156 extern char *__progname;
 157
 158 /* Server configuration options. */
 159 ServerOptions options;
 160
 161 /* Name of the server configuration file. */
 162 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
 163
 164 /*
 165  * Debug mode flag.  This can be set on the command line.  If debug
 166  * mode is enabled, extra debugging output will be sent to the system
 167  * log, the daemon will not go to background, and will exit after processing
 168  * the first connection.
 169  */
 170 int debug_flag = 0;
 171
 172 /*
 173  * Indicating that the daemon should only test the configuration and keys.
 174  * If test_flag > 1 ("-T" flag), then sshd will also dump the effective
 175  * configuration, optionally using connection information provided by the
 176  * "-C" flag.
 177  */
 178 static int test_flag = 0;
 179
 180 /* Flag indicating that the daemon is being started from inetd. */
 181 static int inetd_flag = 0;
 182
 183 /* Flag indicating that sshd should not detach and become a daemon. */
 184 static int no_daemon_flag = 0;
 185
 186 /* debug goes to stderr unless inetd_flag is set */
 187 static int log_stderr = 0;
 188
 189 /* Saved arguments to main(). */
 190 static char **saved_argv;
 191 static int saved_argc;
 192
 193 /* re-exec */
 194 static int rexeced_flag = 0;
 195 static int rexec_flag = 1;
 196 static int rexec_argc = 0;
 197 static char **rexec_argv;
 198
 199 /*
 200  * The sockets that the server is listening; this is used in the SIGHUP
 201  * signal handler.
 202  */
 203 #define MAX_LISTEN_SOCKS        16
 204 static int listen_socks[MAX_LISTEN_SOCKS];
 205 static int num_listen_socks = 0;
 206
 207 /* Daemon's agent connection */
 208 int auth_sock = -1;
 209 static int have_agent = 0;
 210
 211 /*
 212  * Any really sensitive data in the application is contained in this
 213  * structure. The idea is that this structure could be locked into memory so
 214  * that the pages do not get written into swap.  However, there are some
 215  * problems. The private key contains BIGNUMs, and we do not (in principle)
 216  * have access to the internals of them, and locking just the structure is
 217  * not very useful.  Currently, memory locking is not implemented.
 218  */
 219 struct {
 220         struct sshkey   **host_keys;            /* all private host keys */
 221         struct sshkey   **host_pubkeys;         /* all public host keys */
 222         struct sshkey   **host_certificates;    /* all public host certificates */
 223         int             have_ssh2_key;
 224 } sensitive_data;
 225
 226 /* This is set to true when a signal is received. */
 227 static volatile sig_atomic_t received_sighup = 0;
 228 static volatile sig_atomic_t received_sigterm = 0;
 229
 230 /* record remote hostname or ip */
 231 u_int utmp_len = HOST_NAME_MAX+1;
 232
 233 /*
 234  * startup_pipes/flags are used for tracking children of the listening sshd
 235  * process early in their lifespans. This tracking is needed for three things:
 236  *
 237  * 1) Implementing the MaxStartups limit of concurrent unauthenticated
 238  *    connections.
 239  * 2) Avoiding a race condition for SIGHUP processing, where child processes
 240  *    may have listen_socks open that could collide with main listener process
 241  *    after it restarts.
 242  * 3) Ensuring that rexec'd sshd processes have received their initial state
 243  *    from the parent listen process before handling SIGHUP.
 244  *
 245  * Child processes signal that they have completed closure of the listen_socks
 246  * and (if applicable) received their rexec state by sending a char over their
 247  * sock. Child processes signal that authentication has completed by closing
 248  * the sock (or by exiting).
 249  */
 250 static int *startup_pipes = NULL;
 251 static int *startup_flags = NULL;       /* Indicates child closed listener */
 252 static int startup_pipe = -1;           /* in child */
 253
 254 /* variables used for privilege separation */
 255 int use_privsep = -1;
 256 struct monitor *pmonitor = NULL;
 257 int privsep_is_preauth = 1;
 258 static int privsep_chroot = 1;
 259
 260 /* global connection state and authentication contexts */
 261 Authctxt *the_authctxt = NULL;
 262 struct ssh *the_active_state;
 263
 264 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */
 265 struct sshauthopt *auth_opts = NULL;
 266
 267 /* sshd_config buffer */
 268 struct sshbuf *cfg;
 269
 270 /* Included files from the configuration file */
 271 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
 272
 273 /* message to be displayed after login */
 274 struct sshbuf *loginmsg;
 275
 276 /* Unprivileged user */
 277 struct passwd *privsep_pw = NULL;
 278
 279 /* Prototypes for various functions defined later in this file. */
 280 void destroy_sensitive_data(void);
 281 void demote_sensitive_data(void);
 282 static void do_ssh2_kex(struct ssh *);
 283
 284 static char *listener_proctitle;
 285
 286 /*
 287  * Close all listening sockets
 288  */
 289 static void
 290 close_listen_socks(void)
 291 {
 292         int i;
 293
 294         for (i = 0; i < num_listen_socks; i++)
 295                 close(listen_socks[i]);
 296         num_listen_socks = 0;
 297 }
 298
 299 static void
 300 close_startup_pipes(void)
 301 {
 302         int i;
 303
 304         if (startup_pipes)
 305                 for (i = 0; i < options.max_startups; i++)
 306                         if (startup_pipes[i] != -1)
 307                                 close(startup_pipes[i]);
 308 }
 309
 310 /*
 311  * Signal handler for SIGHUP.  Sshd execs itself when it receives SIGHUP;
 312  * the effect is to reread the configuration file (and to regenerate
 313  * the server key).
 314  */
 315
 316 /*ARGSUSED*/
 317 static void
 318 sighup_handler(int sig)
 319 {
 320         received_sighup = 1;
 321 }
 322
 323 /*
 324  * Called from the main program after receiving SIGHUP.
 325  * Restarts the server.
 326  */
 327 static void
 328 sighup_restart(void)
 329 {
 330         logit("Received SIGHUP; restarting.");
 331         if (options.pid_file != NULL)
 332                 unlink(options.pid_file);
 333         platform_pre_restart();
 334         close_listen_socks();
 335         close_startup_pipes();
 336         ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */
 337         execv(saved_argv[0], saved_argv);
 338         logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
 339             strerror(errno));
 340         exit(1);
 341 }
 342
 343 /*
 344  * Generic signal handler for terminating signals in the master daemon.
 345  */
 346 /*ARGSUSED*/
 347 static void
 348 sigterm_handler(int sig)
 349 {
 350         received_sigterm = sig;
 351 }
 352
 353 /*
 354  * SIGCHLD handler.  This is called whenever a child dies.  This will then
 355  * reap any zombies left by exited children.
 356  */
 357 /*ARGSUSED*/
 358 static void
 359 main_sigchld_handler(int sig)
 360 {
 361         int save_errno = errno;
 362         pid_t pid;
 363         int status;
 364
 365         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
 366             (pid == -1 && errno == EINTR))
 367                 ;
 368         errno = save_errno;
 369 }
 370
 371 /*
 372  * Signal handler for the alarm after the login grace period has expired.
 373  */
 374 /*ARGSUSED*/
 375 static void
 376 grace_alarm_handler(int sig)
 377 {
 378         /*
 379          * Try to kill any processes that we have spawned, E.g. authorized
 380          * keys command helpers or privsep children.
 381          */
 382         if (getpgid(0) == getpid()) {
 383                 ssh_signal(SIGTERM, SIG_IGN);
 384                 kill(0, SIGTERM);
 385         }
 386
 387         BLACKLIST_NOTIFY(the_active_state, BLACKLIST_AUTH_FAIL, "ssh");
 388
 389         /* Log error and exit. */
 390         sigdie("Timeout before authentication for %s port %d",
 391             ssh_remote_ipaddr(the_active_state),
 392             ssh_remote_port(the_active_state));
 393 }
 394
 395 /* Destroy the host and server keys.  They will no longer be needed. */
 396 void
 397 destroy_sensitive_data(void)
 398 {
 399         u_int i;
 400
 401         for (i = 0; i < options.num_host_key_files; i++) {
 402                 if (sensitive_data.host_keys[i]) {
 403                         sshkey_free(sensitive_data.host_keys[i]);
 404                         sensitive_data.host_keys[i] = NULL;
 405                 }
 406                 if (sensitive_data.host_certificates[i]) {
 407                         sshkey_free(sensitive_data.host_certificates[i]);
 408                         sensitive_data.host_certificates[i] = NULL;
 409                 }
 410         }
 411 }
 412
 413 /* Demote private to public keys for network child */
 414 void
 415 demote_sensitive_data(void)
 416 {
 417         struct sshkey *tmp;
 418         u_int i;
 419         int r;
 420
 421         for (i = 0; i < options.num_host_key_files; i++) {
 422                 if (sensitive_data.host_keys[i]) {
 423                         if ((r = sshkey_from_private(
 424                             sensitive_data.host_keys[i], &tmp)) != 0)
 425                                 fatal_r(r, "could not demote host %s key",
 426                                     sshkey_type(sensitive_data.host_keys[i]));
 427                         sshkey_free(sensitive_data.host_keys[i]);
 428                         sensitive_data.host_keys[i] = tmp;
 429                 }
 430                 /* Certs do not need demotion */
 431         }
 432 }
 433
 434 static void
 435 reseed_prngs(void)
 436 {
 437         u_int32_t rnd[256];
 438
 439 #ifdef WITH_OPENSSL
 440         RAND_poll();
 441 #endif
 442         arc4random_stir(); /* noop on recent arc4random() implementations */
 443         arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
 444
 445 #ifdef WITH_OPENSSL
 446         RAND_seed(rnd, sizeof(rnd));
 447         /* give libcrypto a chance to notice the PID change */
 448         if ((RAND_bytes((u_char *)rnd, 1)) != 1)
 449                 fatal("%s: RAND_bytes failed", __func__);
 450 #endif
 451
 452         explicit_bzero(rnd, sizeof(rnd));
 453 }
 454
 455 static void
 456 privsep_preauth_child(void)
 457 {
 458         gid_t gidset[1];
 459
 460         /* Enable challenge-response authentication for privilege separation */
 461         privsep_challenge_enable();
 462
 463 #ifdef GSSAPI
 464         /* Cache supported mechanism OIDs for later use */
 465         ssh_gssapi_prepare_supported_oids();
 466 #endif
 467
 468         reseed_prngs();
 469
 470         /* Demote the private keys to public keys. */
 471         demote_sensitive_data();
 472
 473         /* Demote the child */
 474         if (privsep_chroot) {
 475                 /* Change our root directory */
 476                 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
 477                         fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
 478                             strerror(errno));
 479                 if (chdir("/") == -1)
 480                         fatal("chdir(\"/\"): %s", strerror(errno));
 481
 482                 /* Drop our privileges */
 483                 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
 484                     (u_int)privsep_pw->pw_gid);
 485                 gidset[0] = privsep_pw->pw_gid;
 486                 if (setgroups(1, gidset) == -1)
 487                         fatal("setgroups: %.100s", strerror(errno));
 488                 permanently_set_uid(privsep_pw);
 489         }
 490 }
 491
 492 static int
 493 privsep_preauth(struct ssh *ssh)
 494 {
 495         int status, r;
 496         pid_t pid;
 497         struct ssh_sandbox *box = NULL;
 498
 499         /* Set up unprivileged child process to deal with network data */
 500         pmonitor = monitor_init();
 501         /* Store a pointer to the kex for later rekeying */
 502         pmonitor->m_pkex = &ssh->kex;
 503
 504         if (use_privsep == PRIVSEP_ON)
 505                 box = ssh_sandbox_init(pmonitor);
 506         pid = fork();
 507         if (pid == -1) {
 508                 fatal("fork of unprivileged child failed");
 509         } else if (pid != 0) {
 510                 debug2("Network child is on pid %ld", (long)pid);
 511
 512                 pmonitor->m_pid = pid;
 513                 if (have_agent) {
 514                         r = ssh_get_authentication_socket(&auth_sock);
 515                         if (r != 0) {
 516                                 error_r(r, "Could not get agent socket");
 517                                 have_agent = 0;
 518                         }
 519                 }
 520                 if (box != NULL)
 521                         ssh_sandbox_parent_preauth(box, pid);
 522                 monitor_child_preauth(ssh, pmonitor);
 523
 524                 /* Wait for the child's exit status */
 525                 while (waitpid(pid, &status, 0) == -1) {
 526                         if (errno == EINTR)
 527                                 continue;
 528                         pmonitor->m_pid = -1;
 529                         fatal_f("waitpid: %s", strerror(errno));
 530                 }
 531                 privsep_is_preauth = 0;
 532                 pmonitor->m_pid = -1;
 533                 if (WIFEXITED(status)) {
 534                         if (WEXITSTATUS(status) != 0)
 535                                 fatal_f("preauth child exited with status %d",
 536                                     WEXITSTATUS(status));
 537                 } else if (WIFSIGNALED(status))
 538                         fatal_f("preauth child terminated by signal %d",
 539                             WTERMSIG(status));
 540                 if (box != NULL)
 541                         ssh_sandbox_parent_finish(box);
 542                 return 1;
 543         } else {
 544                 /* child */
 545                 close(pmonitor->m_sendfd);
 546                 close(pmonitor->m_log_recvfd);
 547
 548                 /* Arrange for logging to be sent to the monitor */
 549                 set_log_handler(mm_log_handler, pmonitor);
 550
 551                 privsep_preauth_child();
 552                 setproctitle("%s", "[net]");
 553                 if (box != NULL)
 554                         ssh_sandbox_child(box);
 555
 556                 return 0;
 557         }
 558 }
 559
 560 static void
 561 privsep_postauth(struct ssh *ssh, Authctxt *authctxt)
 562 {
 563 #ifdef DISABLE_FD_PASSING
 564         if (1) {
 565 #else
 566         if (authctxt->pw->pw_uid == 0) {
 567 #endif
 568                 /* File descriptor passing is broken or root login */
 569                 use_privsep = 0;
 570                 goto skip;
 571         }
 572
 573         /* New socket pair */
 574         monitor_reinit(pmonitor);
 575
 576         pmonitor->m_pid = fork();
 577         if (pmonitor->m_pid == -1)
 578                 fatal("fork of unprivileged child failed");
 579         else if (pmonitor->m_pid != 0) {
 580                 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
 581                 sshbuf_reset(loginmsg);
 582                 monitor_clear_keystate(ssh, pmonitor);
 583                 monitor_child_postauth(ssh, pmonitor);
 584
 585                 /* NEVERREACHED */
 586                 exit(0);
 587         }
 588
 589         /* child */
 590
 591         close(pmonitor->m_sendfd);
 592         pmonitor->m_sendfd = -1;
 593
 594         /* Demote the private keys to public keys. */
 595         demote_sensitive_data();
 596
 597         reseed_prngs();
 598
 599         /* Drop privileges */
 600         do_setusercontext(authctxt->pw);
 601
 602  skip:
 603         /* It is safe now to apply the key state */
 604         monitor_apply_keystate(ssh, pmonitor);
 605
 606         /*
 607          * Tell the packet layer that authentication was successful, since
 608          * this information is not part of the key state.
 609          */
 610         ssh_packet_set_authenticated(ssh);
 611 }
 612
 613 static void
 614 append_hostkey_type(struct sshbuf *b, const char *s)
 615 {
 616         int r;
 617
 618         if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
 619                 debug3_f("%s key not permitted by HostkeyAlgorithms", s);
 620                 return;
 621         }
 622         if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
 623                 fatal_fr(r, "sshbuf_putf");
 624 }
 625
 626 static char *
 627 list_hostkey_types(void)
 628 {
 629         struct sshbuf *b;
 630         struct sshkey *key;
 631         char *ret;
 632         u_int i;
 633
 634         if ((b = sshbuf_new()) == NULL)
 635                 fatal_f("sshbuf_new failed");
 636         for (i = 0; i < options.num_host_key_files; i++) {
 637                 key = sensitive_data.host_keys[i];
 638                 if (key == NULL)
 639                         key = sensitive_data.host_pubkeys[i];
 640                 if (key == NULL)
 641                         continue;
 642                 switch (key->type) {
 643                 case KEY_RSA:
 644                         /* for RSA we also support SHA2 signatures */
 645                         append_hostkey_type(b, "rsa-sha2-512");
 646                         append_hostkey_type(b, "rsa-sha2-256");
 647                         /* FALLTHROUGH */
 648                 case KEY_DSA:
 649                 case KEY_ECDSA:
 650                 case KEY_ED25519:
 651                 case KEY_ECDSA_SK:
 652                 case KEY_ED25519_SK:
 653                 case KEY_XMSS:
 654                         append_hostkey_type(b, sshkey_ssh_name(key));
 655                         break;
 656                 }
 657                 /* If the private key has a cert peer, then list that too */
 658                 key = sensitive_data.host_certificates[i];
 659                 if (key == NULL)
 660                         continue;
 661                 switch (key->type) {
 662                 case KEY_RSA_CERT:
 663                         /* for RSA we also support SHA2 signatures */
 664                         append_hostkey_type(b,
 665                             "rsa-sha2-512-cert-v01@openssh.com");
 666                         append_hostkey_type(b,
 667                             "rsa-sha2-256-cert-v01@openssh.com");
 668                         /* FALLTHROUGH */
 669                 case KEY_DSA_CERT:
 670                 case KEY_ECDSA_CERT:
 671                 case KEY_ED25519_CERT:
 672                 case KEY_ECDSA_SK_CERT:
 673                 case KEY_ED25519_SK_CERT:
 674                 case KEY_XMSS_CERT:
 675                         append_hostkey_type(b, sshkey_ssh_name(key));
 676                         break;
 677                 }
 678         }
 679         if ((ret = sshbuf_dup_string(b)) == NULL)
 680                 fatal_f("sshbuf_dup_string failed");
 681         sshbuf_free(b);
 682         debug_f("%s", ret);
 683         return ret;
 684 }
 685
 686 static struct sshkey *
 687 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
 688 {
 689         u_int i;
 690         struct sshkey *key;
 691
 692         for (i = 0; i < options.num_host_key_files; i++) {
 693                 switch (type) {
 694                 case KEY_RSA_CERT:
 695                 case KEY_DSA_CERT:
 696                 case KEY_ECDSA_CERT:
 697                 case KEY_ED25519_CERT:
 698                 case KEY_ECDSA_SK_CERT:
 699                 case KEY_ED25519_SK_CERT:
 700                 case KEY_XMSS_CERT:
 701                         key = sensitive_data.host_certificates[i];
 702                         break;
 703                 default:
 704                         key = sensitive_data.host_keys[i];
 705                         if (key == NULL && !need_private)
 706                                 key = sensitive_data.host_pubkeys[i];
 707                         break;
 708                 }
 709                 if (key == NULL || key->type != type)
 710                         continue;
 711                 switch (type) {
 712                 case KEY_ECDSA:
 713                 case KEY_ECDSA_SK:
 714                 case KEY_ECDSA_CERT:
 715                 case KEY_ECDSA_SK_CERT:
 716                         if (key->ecdsa_nid != nid)
 717                                 continue;
 718                         /* FALLTHROUGH */
 719                 default:
 720                         return need_private ?
 721                             sensitive_data.host_keys[i] : key;
 722                 }
 723         }
 724         return NULL;
 725 }
 726
 727 struct sshkey *
 728 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
 729 {
 730         return get_hostkey_by_type(type, nid, 0, ssh);
 731 }
 732
 733 struct sshkey *
 734 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
 735 {
 736         return get_hostkey_by_type(type, nid, 1, ssh);
 737 }
 738
 739 struct sshkey *
 740 get_hostkey_by_index(int ind)
 741 {
 742         if (ind < 0 || (u_int)ind >= options.num_host_key_files)
 743                 return (NULL);
 744         return (sensitive_data.host_keys[ind]);
 745 }
 746
 747 struct sshkey *
 748 get_hostkey_public_by_index(int ind, struct ssh *ssh)
 749 {
 750         if (ind < 0 || (u_int)ind >= options.num_host_key_files)
 751                 return (NULL);
 752         return (sensitive_data.host_pubkeys[ind]);
 753 }
 754
 755 int
 756 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
 757 {
 758         u_int i;
 759
 760         for (i = 0; i < options.num_host_key_files; i++) {
 761                 if (sshkey_is_cert(key)) {
 762                         if (key == sensitive_data.host_certificates[i] ||
 763                             (compare && sensitive_data.host_certificates[i] &&
 764                             sshkey_equal(key,
 765                             sensitive_data.host_certificates[i])))
 766                                 return (i);
 767                 } else {
 768                         if (key == sensitive_data.host_keys[i] ||
 769                             (compare && sensitive_data.host_keys[i] &&
 770                             sshkey_equal(key, sensitive_data.host_keys[i])))
 771                                 return (i);
 772                         if (key == sensitive_data.host_pubkeys[i] ||
 773                             (compare && sensitive_data.host_pubkeys[i] &&
 774                             sshkey_equal(key, sensitive_data.host_pubkeys[i])))
 775                                 return (i);
 776                 }
 777         }
 778         return (-1);
 779 }
 780
 781 /* Inform the client of all hostkeys */
 782 static void
 783 notify_hostkeys(struct ssh *ssh)
 784 {
 785         struct sshbuf *buf;
 786         struct sshkey *key;
 787         u_int i, nkeys;
 788         int r;
 789         char *fp;
 790
 791         /* Some clients cannot cope with the hostkeys message, skip those. */
 792         if (ssh->compat & SSH_BUG_HOSTKEYS)
 793                 return;
 794
 795         if ((buf = sshbuf_new()) == NULL)
 796                 fatal_f("sshbuf_new");
 797         for (i = nkeys = 0; i < options.num_host_key_files; i++) {
 798                 key = get_hostkey_public_by_index(i, ssh);
 799                 if (key == NULL || key->type == KEY_UNSPEC ||
 800                     sshkey_is_cert(key))
 801                         continue;
 802                 fp = sshkey_fingerprint(key, options.fingerprint_hash,
 803                     SSH_FP_DEFAULT);
 804                 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp);
 805                 free(fp);
 806                 if (nkeys == 0) {
 807                         /*
 808                          * Start building the request when we find the
 809                          * first usable key.
 810                          */
 811                         if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
 812                             (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 ||
 813                             (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */
 814                                 sshpkt_fatal(ssh, r, "%s: start request", __func__);
 815                 }
 816                 /* Append the key to the request */
 817                 sshbuf_reset(buf);
 818                 if ((r = sshkey_putb(key, buf)) != 0)
 819                         fatal_fr(r, "couldn't put hostkey %d", i);
 820                 if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
 821                         sshpkt_fatal(ssh, r, "%s: append key", __func__);
 822                 nkeys++;
 823         }
 824         debug3_f("sent %u hostkeys", nkeys);
 825         if (nkeys == 0)
 826                 fatal_f("no hostkeys");
 827         if ((r = sshpkt_send(ssh)) != 0)
 828                 sshpkt_fatal(ssh, r, "%s: send", __func__);
 829         sshbuf_free(buf);
 830 }
 831
 832 /*
 833  * returns 1 if connection should be dropped, 0 otherwise.
 834  * dropping starts at connection #max_startups_begin with a probability
 835  * of (max_startups_rate/100). the probability increases linearly until
 836  * all connections are dropped for startups > max_startups
 837  */
 838 static int
 839 should_drop_connection(int startups)
 840 {
 841         int p, r;
 842
 843         if (startups < options.max_startups_begin)
 844                 return 0;
 845         if (startups >= options.max_startups)
 846                 return 1;
 847         if (options.max_startups_rate == 100)
 848                 return 1;
 849
 850         p  = 100 - options.max_startups_rate;
 851         p *= startups - options.max_startups_begin;
 852         p /= options.max_startups - options.max_startups_begin;
 853         p += options.max_startups_rate;
 854         r = arc4random_uniform(100);
 855
 856         debug_f("p %d, r %d", p, r);
 857         return (r < p) ? 1 : 0;
 858 }
 859
 860 /*
 861  * Check whether connection should be accepted by MaxStartups.
 862  * Returns 0 if the connection is accepted. If the connection is refused,
 863  * returns 1 and attempts to send notification to client.
 864  * Logs when the MaxStartups condition is entered or exited, and periodically
 865  * while in that state.
 866  */
 867 static int
 868 drop_connection(int sock, int startups, int notify_pipe)
 869 {
 870         char *laddr, *raddr;
 871         const char msg[] = "Exceeded MaxStartups\r\n";
 872         static time_t last_drop, first_drop;
 873         static u_int ndropped;
 874         LogLevel drop_level = SYSLOG_LEVEL_VERBOSE;
 875         time_t now;
 876
 877         now = monotime();
 878         if (!should_drop_connection(startups) &&
 879             srclimit_check_allow(sock, notify_pipe) == 1) {
 880                 if (last_drop != 0 &&
 881                     startups < options.max_startups_begin - 1) {
 882                         /* XXX maybe need better hysteresis here */
 883                         logit("exited MaxStartups throttling after %s, "
 884                             "%u connections dropped",
 885                             fmt_timeframe(now - first_drop), ndropped);
 886                         last_drop = 0;
 887                 }
 888                 return 0;
 889         }
 890
 891 #define SSHD_MAXSTARTUPS_LOG_INTERVAL   (5 * 60)
 892         if (last_drop == 0) {
 893                 error("beginning MaxStartups throttling");
 894                 drop_level = SYSLOG_LEVEL_INFO;
 895                 first_drop = now;
 896                 ndropped = 0;
 897         } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) {
 898                 /* Periodic logs */
 899                 error("in MaxStartups throttling for %s, "
 900                     "%u connections dropped",
 901                     fmt_timeframe(now - first_drop), ndropped + 1);
 902                 drop_level = SYSLOG_LEVEL_INFO;
 903         }
 904         last_drop = now;
 905         ndropped++;
 906
 907         laddr = get_local_ipaddr(sock);
 908         raddr = get_peer_ipaddr(sock);
 909         do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d "
 910             "past MaxStartups", startups, raddr, get_peer_port(sock),
 911             laddr, get_local_port(sock));
 912         free(laddr);
 913         free(raddr);
 914         /* best-effort notification to client */
 915         (void)write(sock, msg, sizeof(msg) - 1);
 916         return 1;
 917 }
 918
 919 static void
 920 usage(void)
 921 {
 922         if (options.version_addendum != NULL &&
 923             *options.version_addendum != '\0')
 924                 fprintf(stderr, "%s %s, %s\n",
 925                     SSH_RELEASE,
 926                     options.version_addendum, SSH_OPENSSL_VERSION);
 927         else
 928                 fprintf(stderr, "%s, %s\n",
 929                     SSH_RELEASE, SSH_OPENSSL_VERSION);
 930         fprintf(stderr,
 931 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
 932 "            [-E log_file] [-f config_file] [-g login_grace_time]\n"
 933 "            [-h host_key_file] [-o option] [-p port] [-u len]\n"
 934         );
 935         exit(1);
 936 }
 937
 938 static void
 939 send_rexec_state(int fd, struct sshbuf *conf)
 940 {
 941         struct sshbuf *m = NULL, *inc = NULL;
 942         struct include_item *item = NULL;
 943         int r;
 944
 945         debug3_f("entering fd = %d config len %zu", fd,
 946             sshbuf_len(conf));
 947
 948         if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
 949                 fatal_f("sshbuf_new failed");
 950
 951         /* pack includes into a string */
 952         TAILQ_FOREACH(item, &includes, entry) {
 953                 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 ||
 954                     (r = sshbuf_put_cstring(inc, item->filename)) != 0 ||
 955                     (r = sshbuf_put_stringb(inc, item->contents)) != 0)
 956                         fatal_fr(r, "compose includes");
 957         }
 958
 959         /*
 960          * Protocol from reexec master to child:
 961          *      string  configuration
 962          *      string  included_files[] {
 963          *              string  selector
 964          *              string  filename
 965          *              string  contents
 966          *      }
 967          *      string  rng_seed (if required)
 968          */
 969         if ((r = sshbuf_put_stringb(m, conf)) != 0 ||
 970             (r = sshbuf_put_stringb(m, inc)) != 0)
 971                 fatal_fr(r, "compose config");
 972 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
 973         rexec_send_rng_seed(m);
 974 #endif
 975         if (ssh_msg_send(fd, 0, m) == -1)
 976                 error_f("ssh_msg_send failed");
 977
 978         sshbuf_free(m);
 979         sshbuf_free(inc);
 980
 981         debug3_f("done");
 982 }
 983
 984 static void
 985 recv_rexec_state(int fd, struct sshbuf *conf)
 986 {
 987         struct sshbuf *m, *inc;
 988         u_char *cp, ver;
 989         size_t len;
 990         int r;
 991         struct include_item *item;
 992
 993         debug3_f("entering fd = %d", fd);
 994
 995         if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
 996                 fatal_f("sshbuf_new failed");
 997         if (ssh_msg_recv(fd, m) == -1)
 998                 fatal_f("ssh_msg_recv failed");
 999         if ((r = sshbuf_get_u8(m, &ver)) != 0)
1000                 fatal_fr(r, "parse version");
1001         if (ver != 0)
1002                 fatal_f("rexec version mismatch");
1003         if ((r = sshbuf_get_string(m, &cp, &len)) != 0 ||
1004             (r = sshbuf_get_stringb(m, inc)) != 0)
1005                 fatal_fr(r, "parse config");
1006
1007 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
1008         rexec_recv_rng_seed(m);
1009 #endif
1010
1011         if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
1012                 fatal_fr(r, "sshbuf_put");
1013
1014         while (sshbuf_len(inc) != 0) {
1015                 item = xcalloc(1, sizeof(*item));
1016                 if ((item->contents = sshbuf_new()) == NULL)
1017                         fatal_f("sshbuf_new failed");
1018                 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 ||
1019                     (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 ||
1020                     (r = sshbuf_get_stringb(inc, item->contents)) != 0)
1021                         fatal_fr(r, "parse includes");
1022                 TAILQ_INSERT_TAIL(&includes, item, entry);
1023         }
1024
1025         free(cp);
1026         sshbuf_free(m);
1027
1028         debug3_f("done");
1029 }
1030
1031 /* Accept a connection from inetd */
1032 static void
1033 server_accept_inetd(int *sock_in, int *sock_out)
1034 {
1035         if (rexeced_flag) {
1036                 close(REEXEC_CONFIG_PASS_FD);
1037                 *sock_in = *sock_out = dup(STDIN_FILENO);
1038         } else {
1039                 *sock_in = dup(STDIN_FILENO);
1040                 *sock_out = dup(STDOUT_FILENO);
1041         }
1042         /*
1043          * We intentionally do not close the descriptors 0, 1, and 2
1044          * as our code for setting the descriptors won't work if
1045          * ttyfd happens to be one of those.
1046          */
1047         if (stdfd_devnull(1, 1, !log_stderr) == -1)
1048                 error_f("stdfd_devnull failed");
1049         debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1050 }
1051
1052 /*
1053  * Listen for TCP connections
1054  */
1055 static void
1056 listen_on_addrs(struct listenaddr *la)
1057 {
1058         int ret, listen_sock;
1059         struct addrinfo *ai;
1060         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1061
1062         for (ai = la->addrs; ai; ai = ai->ai_next) {
1063                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1064                         continue;
1065                 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1066                         fatal("Too many listen sockets. "
1067                             "Enlarge MAX_LISTEN_SOCKS");
1068                 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1069                     ntop, sizeof(ntop), strport, sizeof(strport),
1070                     NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1071                         error("getnameinfo failed: %.100s",
1072                             ssh_gai_strerror(ret));
1073                         continue;
1074                 }
1075                 /* Create socket for listening. */
1076                 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1077                     ai->ai_protocol);
1078                 if (listen_sock == -1) {
1079                         /* kernel may not support ipv6 */
1080                         verbose("socket: %.100s", strerror(errno));
1081                         continue;
1082                 }
1083                 if (set_nonblock(listen_sock) == -1) {
1084                         close(listen_sock);
1085                         continue;
1086                 }
1087                 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
1088                         verbose("socket: CLOEXEC: %s", strerror(errno));
1089                         close(listen_sock);
1090                         continue;
1091                 }
1092                 /* Socket options */
1093                 set_reuseaddr(listen_sock);
1094                 if (la->rdomain != NULL &&
1095                     set_rdomain(listen_sock, la->rdomain) == -1) {
1096                         close(listen_sock);
1097                         continue;
1098                 }
1099
1100                 /* Only communicate in IPv6 over AF_INET6 sockets. */
1101                 if (ai->ai_family == AF_INET6)
1102                         sock_set_v6only(listen_sock);
1103
1104                 debug("Bind to port %s on %s.", strport, ntop);
1105
1106                 /* Bind the socket to the desired port. */
1107                 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) {
1108                         error("Bind to port %s on %s failed: %.200s.",
1109                             strport, ntop, strerror(errno));
1110                         close(listen_sock);
1111                         continue;
1112                 }
1113                 listen_socks[num_listen_socks] = listen_sock;
1114                 num_listen_socks++;
1115
1116                 /* Start listening on the port. */
1117                 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1)
1118                         fatal("listen on [%s]:%s: %.100s",
1119                             ntop, strport, strerror(errno));
1120                 logit("Server listening on %s port %s%s%s.",
1121                     ntop, strport,
1122                     la->rdomain == NULL ? "" : " rdomain ",
1123                     la->rdomain == NULL ? "" : la->rdomain);
1124         }
1125 }
1126
1127 static void
1128 server_listen(void)
1129 {
1130         u_int i;
1131
1132         /* Initialise per-source limit tracking. */
1133         srclimit_init(options.max_startups, options.per_source_max_startups,
1134             options.per_source_masklen_ipv4, options.per_source_masklen_ipv6);
1135
1136         for (i = 0; i < options.num_listen_addrs; i++) {
1137                 listen_on_addrs(&options.listen_addrs[i]);
1138                 freeaddrinfo(options.listen_addrs[i].addrs);
1139                 free(options.listen_addrs[i].rdomain);
1140                 memset(&options.listen_addrs[i], 0,
1141                     sizeof(options.listen_addrs[i]));
1142         }
1143         free(options.listen_addrs);
1144         options.listen_addrs = NULL;
1145         options.num_listen_addrs = 0;
1146
1147         if (!num_listen_socks)
1148                 fatal("Cannot bind any address.");
1149 }
1150
1151 /*
1152  * The main TCP accept loop. Note that, for the non-debug case, returns
1153  * from this function are in a forked subprocess.
1154  */
1155 static void
1156 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1157 {
1158         struct pollfd *pfd = NULL;
1159         int i, j, ret, npfd;
1160         int ostartups = -1, startups = 0, listening = 0, lameduck = 0;
1161         int startup_p[2] = { -1 , -1 }, *startup_pollfd;
1162         char c = 0;
1163         struct sockaddr_storage from;
1164         socklen_t fromlen;
1165         pid_t pid;
1166         u_char rnd[256];
1167         sigset_t nsigset, osigset;
1168 #ifdef LIBWRAP
1169         struct request_info req;
1170
1171         request_init(&req, RQ_DAEMON, __progname, 0);
1172 #endif
1173
1174         /* pipes connected to unauthenticated child sshd processes */
1175         startup_pipes = xcalloc(options.max_startups, sizeof(int));
1176         startup_flags = xcalloc(options.max_startups, sizeof(int));
1177         startup_pollfd = xcalloc(options.max_startups, sizeof(int));
1178         for (i = 0; i < options.max_startups; i++)
1179                 startup_pipes[i] = -1;
1180
1181         /*
1182          * Prepare signal mask that we use to block signals that might set
1183          * received_sigterm or received_sighup, so that we are guaranteed
1184          * to immediately wake up the ppoll if a signal is received after
1185          * the flag is checked.
1186          */
1187         sigemptyset(&nsigset);
1188         sigaddset(&nsigset, SIGHUP);
1189         sigaddset(&nsigset, SIGCHLD);
1190         sigaddset(&nsigset, SIGTERM);
1191         sigaddset(&nsigset, SIGQUIT);
1192
1193         /* sized for worst-case */
1194         pfd = xcalloc(num_listen_socks + options.max_startups,
1195             sizeof(struct pollfd));
1196
1197         /*
1198          * Stay listening for connections until the system crashes or
1199          * the daemon is killed with a signal.
1200          */
1201         for (;;) {
1202                 sigprocmask(SIG_BLOCK, &nsigset, &osigset);
1203                 if (received_sigterm) {
1204                         logit("Received signal %d; terminating.",
1205                             (int) received_sigterm);
1206                         close_listen_socks();
1207                         if (options.pid_file != NULL)
1208                                 unlink(options.pid_file);
1209                         exit(received_sigterm == SIGTERM ? 0 : 255);
1210                 }
1211                 if (ostartups != startups) {
1212                         setproctitle("%s [listener] %d of %d-%d startups",
1213                             listener_proctitle, startups,
1214                             options.max_startups_begin, options.max_startups);
1215                         ostartups = startups;
1216                 }
1217                 if (received_sighup) {
1218                         if (!lameduck) {
1219                                 debug("Received SIGHUP; waiting for children");
1220                                 close_listen_socks();
1221                                 lameduck = 1;
1222                         }
1223                         if (listening <= 0) {
1224                                 sigprocmask(SIG_SETMASK, &osigset, NULL);
1225                                 sighup_restart();
1226                         }
1227                 }
1228
1229                 for (i = 0; i < num_listen_socks; i++) {
1230                         pfd[i].fd = listen_socks[i];
1231                         pfd[i].events = POLLIN;
1232                 }
1233                 npfd = num_listen_socks;
1234                 for (i = 0; i < options.max_startups; i++) {
1235                         startup_pollfd[i] = -1;
1236                         if (startup_pipes[i] != -1) {
1237                                 pfd[npfd].fd = startup_pipes[i];
1238                                 pfd[npfd].events = POLLIN;
1239                                 startup_pollfd[i] = npfd++;
1240                         }
1241                 }
1242
1243                 /* Wait until a connection arrives or a child exits. */
1244                 ret = ppoll(pfd, npfd, NULL, &osigset);
1245                 if (ret == -1 && errno != EINTR) {
1246                         error("ppoll: %.100s", strerror(errno));
1247                         if (errno == EINVAL)
1248                                 cleanup_exit(1); /* can't recover */
1249                 }
1250                 sigprocmask(SIG_SETMASK, &osigset, NULL);
1251                 if (ret == -1)
1252                         continue;
1253
1254                 for (i = 0; i < options.max_startups; i++) {
1255                         if (startup_pipes[i] == -1 ||
1256                             startup_pollfd[i] == -1 ||
1257                             !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP)))
1258                                 continue;
1259                         switch (read(startup_pipes[i], &c, sizeof(c))) {
1260                         case -1:
1261                                 if (errno == EINTR || errno == EAGAIN)
1262                                         continue;
1263                                 if (errno != EPIPE) {
1264                                         error_f("startup pipe %d (fd=%d): "
1265                                             "read %s", i, startup_pipes[i],
1266                                             strerror(errno));
1267                                 }
1268                                 /* FALLTHROUGH */
1269                         case 0:
1270                                 /* child exited or completed auth */
1271                                 close(startup_pipes[i]);
1272                                 srclimit_done(startup_pipes[i]);
1273                                 startup_pipes[i] = -1;
1274                                 startups--;
1275                                 if (startup_flags[i])
1276                                         listening--;
1277                                 break;
1278                         case 1:
1279                                 /* child has finished preliminaries */
1280                                 if (startup_flags[i]) {
1281                                         listening--;
1282                                         startup_flags[i] = 0;
1283                                 }
1284                                 break;
1285                         }
1286                 }
1287                 for (i = 0; i < num_listen_socks; i++) {
1288                         if (!(pfd[i].revents & POLLIN))
1289                                 continue;
1290                         fromlen = sizeof(from);
1291                         *newsock = accept(listen_socks[i],
1292                             (struct sockaddr *)&from, &fromlen);
1293                         if (*newsock == -1) {
1294                                 if (errno != EINTR && errno != EWOULDBLOCK &&
1295                                     errno != ECONNABORTED && errno != EAGAIN)
1296                                         error("accept: %.100s",
1297                                             strerror(errno));
1298                                 if (errno == EMFILE || errno == ENFILE)
1299                                         usleep(100 * 1000);
1300                                 continue;
1301                         }
1302 #ifdef LIBWRAP
1303                         /* Check whether logins are denied from this host. */
1304                         request_set(&req, RQ_FILE, *newsock,
1305                             RQ_CLIENT_NAME, "", RQ_CLIENT_ADDR, "", 0);
1306                         sock_host(&req);
1307                         if (!hosts_access(&req)) {
1308                                 const struct linger l = { .l_onoff = 1,
1309                                     .l_linger  = 0 };
1310
1311                                 (void )setsockopt(*newsock, SOL_SOCKET,
1312                                     SO_LINGER, &l, sizeof(l));
1313                                 (void )close(*newsock);
1314                                 /*
1315                                  * Mimic message from libwrap's refuse()
1316                                  * exactly.  sshguard, and supposedly lots
1317                                  * of custom made scripts rely on it.
1318                                  */
1319                                 syslog(deny_severity,
1320                                     "refused connect from %s (%s)",
1321                                     eval_client(&req),
1322                                     eval_hostaddr(req.client));
1323                                 debug("Connection refused by tcp wrapper");
1324                                 continue;
1325                         }
1326 #endif /* LIBWRAP */
1327                         if (unset_nonblock(*newsock) == -1) {
1328                                 close(*newsock);
1329                                 continue;
1330                         }
1331                         if (pipe(startup_p) == -1) {
1332                                 error_f("pipe(startup_p): %s", strerror(errno));
1333                                 close(*newsock);
1334                                 continue;
1335                         }
1336                         if (drop_connection(*newsock, startups, startup_p[0])) {
1337                                 close(*newsock);
1338                                 close(startup_p[0]);
1339                                 close(startup_p[1]);
1340                                 continue;
1341                         }
1342
1343                         if (rexec_flag && socketpair(AF_UNIX,
1344                             SOCK_STREAM, 0, config_s) == -1) {
1345                                 error("reexec socketpair: %s",
1346                                     strerror(errno));
1347                                 close(*newsock);
1348                                 close(startup_p[0]);
1349                                 close(startup_p[1]);
1350                                 continue;
1351                         }
1352
1353                         for (j = 0; j < options.max_startups; j++)
1354                                 if (startup_pipes[j] == -1) {
1355                                         startup_pipes[j] = startup_p[0];
1356                                         startups++;
1357                                         startup_flags[j] = 1;
1358                                         break;
1359                                 }
1360
1361                         /*
1362                          * Got connection.  Fork a child to handle it, unless
1363                          * we are in debugging mode.
1364                          */
1365                         if (debug_flag) {
1366                                 /*
1367                                  * In debugging mode.  Close the listening
1368                                  * socket, and start processing the
1369                                  * connection without forking.
1370                                  */
1371                                 debug("Server will not fork when running in debugging mode.");
1372                                 close_listen_socks();
1373                                 *sock_in = *newsock;
1374                                 *sock_out = *newsock;
1375                                 close(startup_p[0]);
1376                                 close(startup_p[1]);
1377                                 startup_pipe = -1;
1378                                 pid = getpid();
1379                                 if (rexec_flag) {
1380                                         send_rexec_state(config_s[0], cfg);
1381                                         close(config_s[0]);
1382                                 }
1383                                 free(pfd);
1384                                 return;
1385                         }
1386
1387                         /*
1388                          * Normal production daemon.  Fork, and have
1389                          * the child process the connection. The
1390                          * parent continues listening.
1391                          */
1392                         platform_pre_fork();
1393                         listening++;
1394                         if ((pid = fork()) == 0) {
1395                                 /*
1396                                  * Child.  Close the listening and
1397                                  * max_startup sockets.  Start using
1398                                  * the accepted socket. Reinitialize
1399                                  * logging (since our pid has changed).
1400                                  * We return from this function to handle
1401                                  * the connection.
1402                                  */
1403                                 platform_post_fork_child();
1404                                 startup_pipe = startup_p[1];
1405                                 close_startup_pipes();
1406                                 close_listen_socks();
1407                                 *sock_in = *newsock;
1408                                 *sock_out = *newsock;
1409                                 log_init(__progname,
1410                                     options.log_level,
1411                                     options.log_facility,
1412                                     log_stderr);
1413                                 if (rexec_flag)
1414                                         close(config_s[0]);
1415                                 else {
1416                                         /*
1417                                          * Signal parent that the preliminaries
1418                                          * for this child are complete. For the
1419                                          * re-exec case, this happens after the
1420                                          * child has received the rexec state
1421                                          * from the server.
1422                                          */
1423                                         (void)atomicio(vwrite, startup_pipe,
1424                                             "\0", 1);
1425                                 }
1426                                 free(pfd);
1427                                 return;
1428                         }
1429
1430                         /* Parent.  Stay in the loop. */
1431                         platform_post_fork_parent(pid);
1432                         if (pid == -1)
1433                                 error("fork: %.100s", strerror(errno));
1434                         else
1435                                 debug("Forked child %ld.", (long)pid);
1436
1437                         close(startup_p[1]);
1438
1439                         if (rexec_flag) {
1440                                 close(config_s[1]);
1441                                 send_rexec_state(config_s[0], cfg);
1442                                 close(config_s[0]);
1443                         }
1444                         close(*newsock);
1445
1446                         /*
1447                          * Ensure that our random state differs
1448                          * from that of the child
1449                          */
1450                         arc4random_stir();
1451                         arc4random_buf(rnd, sizeof(rnd));
1452 #ifdef WITH_OPENSSL
1453                         RAND_seed(rnd, sizeof(rnd));
1454                         if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1455                                 fatal("%s: RAND_bytes failed", __func__);
1456 #endif
1457                         explicit_bzero(rnd, sizeof(rnd));
1458                 }
1459         }
1460 }
1461
1462 /*
1463  * If IP options are supported, make sure there are none (log and
1464  * return an error if any are found).  Basically we are worried about
1465  * source routing; it can be used to pretend you are somebody
1466  * (ip-address) you are not. That itself may be "almost acceptable"
1467  * under certain circumstances, but rhosts authentication is useless
1468  * if source routing is accepted. Notice also that if we just dropped
1469  * source routing here, the other side could use IP spoofing to do
1470  * rest of the interaction and could still bypass security.  So we
1471  * exit here if we detect any IP options.
1472  */
1473 static void
1474 check_ip_options(struct ssh *ssh)
1475 {
1476 #ifdef IP_OPTIONS
1477         int sock_in = ssh_packet_get_connection_in(ssh);
1478         struct sockaddr_storage from;
1479         u_char opts[200];
1480         socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
1481         char text[sizeof(opts) * 3 + 1];
1482
1483         memset(&from, 0, sizeof(from));
1484         if (getpeername(sock_in, (struct sockaddr *)&from,
1485             &fromlen) == -1)
1486                 return;
1487         if (from.ss_family != AF_INET)
1488                 return;
1489         /* XXX IPv6 options? */
1490
1491         if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1492             &option_size) >= 0 && option_size != 0) {
1493                 text[0] = '\0';
1494                 for (i = 0; i < option_size; i++)
1495                         snprintf(text + i*3, sizeof(text) - i*3,
1496                             " %2.2x", opts[i]);
1497                 fatal("Connection from %.100s port %d with IP opts: %.800s",
1498                     ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1499         }
1500         return;
1501 #endif /* IP_OPTIONS */
1502 }
1503
1504 /* Set the routing domain for this process */
1505 static void
1506 set_process_rdomain(struct ssh *ssh, const char *name)
1507 {
1508 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
1509         if (name == NULL)
1510                 return; /* default */
1511
1512         if (strcmp(name, "%D") == 0) {
1513                 /* "expands" to routing domain of connection */
1514                 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1515                         return;
1516         }
1517         /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
1518         return sys_set_process_rdomain(name);
1519 #elif defined(__OpenBSD__)
1520         int rtable, ortable = getrtable();
1521         const char *errstr;
1522
1523         if (name == NULL)
1524                 return; /* default */
1525
1526         if (strcmp(name, "%D") == 0) {
1527                 /* "expands" to routing domain of connection */
1528                 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1529                         return;
1530         }
1531
1532         rtable = (int)strtonum(name, 0, 255, &errstr);
1533         if (errstr != NULL) /* Shouldn't happen */
1534                 fatal("Invalid routing domain \"%s\": %s", name, errstr);
1535         if (rtable != ortable && setrtable(rtable) != 0)
1536                 fatal("Unable to set routing domain %d: %s",
1537                     rtable, strerror(errno));
1538         debug_f("set routing domain %d (was %d)", rtable, ortable);
1539 #else /* defined(__OpenBSD__) */
1540         fatal("Unable to set routing domain: not supported in this platform");
1541 #endif
1542 }
1543
1544 static void
1545 accumulate_host_timing_secret(struct sshbuf *server_cfg,
1546     struct sshkey *key)
1547 {
1548         static struct ssh_digest_ctx *ctx;
1549         u_char *hash;
1550         size_t len;
1551         struct sshbuf *buf;
1552         int r;
1553
1554         if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
1555                 fatal_f("ssh_digest_start");
1556         if (key == NULL) { /* finalize */
1557                 /* add server config in case we are using agent for host keys */
1558                 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
1559                     sshbuf_len(server_cfg)) != 0)
1560                         fatal_f("ssh_digest_update");
1561                 len = ssh_digest_bytes(SSH_DIGEST_SHA512);
1562                 hash = xmalloc(len);
1563                 if (ssh_digest_final(ctx, hash, len) != 0)
1564                         fatal_f("ssh_digest_final");
1565                 options.timing_secret = PEEK_U64(hash);
1566                 freezero(hash, len);
1567                 ssh_digest_free(ctx);
1568                 ctx = NULL;
1569                 return;
1570         }
1571         if ((buf = sshbuf_new()) == NULL)
1572                 fatal_f("could not allocate buffer");
1573         if ((r = sshkey_private_serialize(key, buf)) != 0)
1574                 fatal_fr(r, "decode key");
1575         if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
1576                 fatal_f("ssh_digest_update");
1577         sshbuf_reset(buf);
1578         sshbuf_free(buf);
1579 }
1580
1581 static char *
1582 prepare_proctitle(int ac, char **av)
1583 {
1584         char *ret = NULL;
1585         int i;
1586
1587         for (i = 0; i < ac; i++)
1588                 xextendf(&ret, " ", "%s", av[i]);
1589         return ret;
1590 }
1591
1592 /*
1593  * Main program for the daemon.
1594  */
1595 int
1596 main(int ac, char **av)
1597 {
1598         struct ssh *ssh = NULL;
1599         extern char *optarg;
1600         extern int optind;
1601         int r, opt, on = 1, already_daemon, remote_port;
1602         int sock_in = -1, sock_out = -1, newsock = -1;
1603         const char *remote_ip, *rdomain;
1604         char *fp, *line, *laddr, *logfile = NULL;
1605         int config_s[2] = { -1 , -1 };
1606         u_int i, j;
1607         u_int64_t ibytes, obytes;
1608         mode_t new_umask;
1609         struct sshkey *key;
1610         struct sshkey *pubkey;
1611         int keytype;
1612         Authctxt *authctxt;
1613         struct connection_info *connection_info = NULL;
1614
1615 #ifdef HAVE_SECUREWARE
1616         (void)set_auth_parameters(ac, av);
1617 #endif
1618         __progname = ssh_get_progname(av[0]);
1619
1620         /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1621         saved_argc = ac;
1622         rexec_argc = ac;
1623         saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1624         for (i = 0; (int)i < ac; i++)
1625                 saved_argv[i] = xstrdup(av[i]);
1626         saved_argv[i] = NULL;
1627
1628 #ifndef HAVE_SETPROCTITLE
1629         /* Prepare for later setproctitle emulation */
1630         compat_init_setproctitle(ac, av);
1631         av = saved_argv;
1632 #endif
1633
1634         if (geteuid() == 0 && setgroups(0, NULL) == -1)
1635                 debug("setgroups(): %.200s", strerror(errno));
1636
1637         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1638         sanitise_stdfd();
1639
1640         seed_rng();
1641
1642         /* Initialize configuration options to their default values. */
1643         initialize_server_options(&options);
1644
1645         /* Parse command-line arguments. */
1646         while ((opt = getopt(ac, av,
1647             "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1648                 switch (opt) {
1649                 case '4':
1650                         options.address_family = AF_INET;
1651                         break;
1652                 case '6':
1653                         options.address_family = AF_INET6;
1654                         break;
1655                 case 'f':
1656                         config_file_name = optarg;
1657                         break;
1658                 case 'c':
1659                         servconf_add_hostcert("[command-line]", 0,
1660                             &options, optarg);
1661                         break;
1662                 case 'd':
1663                         if (debug_flag == 0) {
1664                                 debug_flag = 1;
1665                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
1666                         } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1667                                 options.log_level++;
1668                         break;
1669                 case 'D':
1670                         no_daemon_flag = 1;
1671                         break;
1672                 case 'E':
1673                         logfile = optarg;
1674                         /* FALLTHROUGH */
1675                 case 'e':
1676                         log_stderr = 1;
1677                         break;
1678                 case 'i':
1679                         inetd_flag = 1;
1680                         break;
1681                 case 'r':
1682                         rexec_flag = 0;
1683                         break;
1684                 case 'R':
1685                         rexeced_flag = 1;
1686                         inetd_flag = 1;
1687                         break;
1688                 case 'Q':
1689                         /* ignored */
1690                         break;
1691                 case 'q':
1692                         options.log_level = SYSLOG_LEVEL_QUIET;
1693                         break;
1694                 case 'b':
1695                         /* protocol 1, ignored */
1696                         break;
1697                 case 'p':
1698                         options.ports_from_cmdline = 1;
1699                         if (options.num_ports >= MAX_PORTS) {
1700                                 fprintf(stderr, "too many ports.\n");
1701                                 exit(1);
1702                         }
1703                         options.ports[options.num_ports++] = a2port(optarg);
1704                         if (options.ports[options.num_ports-1] <= 0) {
1705                                 fprintf(stderr, "Bad port number.\n");
1706                                 exit(1);
1707                         }
1708                         break;
1709                 case 'g':
1710                         if ((options.login_grace_time = convtime(optarg)) == -1) {
1711                                 fprintf(stderr, "Invalid login grace time.\n");
1712                                 exit(1);
1713                         }
1714                         break;
1715                 case 'k':
1716                         /* protocol 1, ignored */
1717                         break;
1718                 case 'h':
1719                         servconf_add_hostkey("[command-line]", 0,
1720                             &options, optarg, 1);
1721                         break;
1722                 case 't':
1723                         test_flag = 1;
1724                         break;
1725                 case 'T':
1726                         test_flag = 2;
1727                         break;
1728                 case 'C':
1729                         connection_info = get_connection_info(ssh, 0, 0);
1730                         if (parse_server_match_testspec(connection_info,
1731                             optarg) == -1)
1732                                 exit(1);
1733                         break;
1734                 case 'u':
1735                         utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1736                         if (utmp_len > HOST_NAME_MAX+1) {
1737                                 fprintf(stderr, "Invalid utmp length.\n");
1738                                 exit(1);
1739                         }
1740                         break;
1741                 case 'o':
1742                         line = xstrdup(optarg);
1743                         if (process_server_config_line(&options, line,
1744                             "command-line", 0, NULL, NULL, &includes) != 0)
1745                                 exit(1);
1746                         free(line);
1747                         break;
1748                 case '?':
1749                 default:
1750                         usage();
1751                         break;
1752                 }
1753         }
1754         if (rexeced_flag || inetd_flag)
1755                 rexec_flag = 0;
1756         if (!test_flag && rexec_flag && !path_absolute(av[0]))
1757                 fatal("sshd re-exec requires execution with an absolute path");
1758         if (rexeced_flag)
1759                 closefrom(REEXEC_MIN_FREE_FD);
1760         else
1761                 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1762
1763         /* If requested, redirect the logs to the specified logfile. */
1764         if (logfile != NULL)
1765                 log_redirect_stderr_to(logfile);
1766         /*
1767          * Force logging to stderr until we have loaded the private host
1768          * key (unless started from inetd)
1769          */
1770         log_init(__progname,
1771             options.log_level == SYSLOG_LEVEL_NOT_SET ?
1772             SYSLOG_LEVEL_INFO : options.log_level,
1773             options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1774             SYSLOG_FACILITY_AUTH : options.log_facility,
1775             log_stderr || !inetd_flag || debug_flag);
1776
1777         /*
1778          * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1779          * root's environment
1780          */
1781         if (getenv("KRB5CCNAME") != NULL)
1782                 (void) unsetenv("KRB5CCNAME");
1783
1784         sensitive_data.have_ssh2_key = 0;
1785
1786         /*
1787          * If we're not doing an extended test do not silently ignore connection
1788          * test params.
1789          */
1790         if (test_flag < 2 && connection_info != NULL)
1791                 fatal("Config test connection parameter (-C) provided without "
1792                     "test mode (-T)");
1793
1794         /* Fetch our configuration */
1795         if ((cfg = sshbuf_new()) == NULL)
1796                 fatal_f("sshbuf_new failed");
1797         if (rexeced_flag) {
1798                 setproctitle("%s", "[rexeced]");
1799                 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg);
1800                 if (!debug_flag) {
1801                         startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1802                         close(REEXEC_STARTUP_PIPE_FD);
1803                         /*
1804                          * Signal parent that this child is at a point where
1805                          * they can go away if they have a SIGHUP pending.
1806                          */
1807                         (void)atomicio(vwrite, startup_pipe, "\0", 1);
1808                 }
1809         } else if (strcasecmp(config_file_name, "none") != 0)
1810                 load_server_config(config_file_name, cfg);
1811
1812         parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1813             cfg, &includes, NULL, rexeced_flag);
1814
1815 #ifdef WITH_OPENSSL
1816         if (options.moduli_file != NULL)
1817                 dh_set_moduli_file(options.moduli_file);
1818 #endif
1819
1820         /* Fill in default values for those options not explicitly set. */
1821         fill_default_server_options(&options);
1822
1823         /* Check that options are sensible */
1824         if (options.authorized_keys_command_user == NULL &&
1825             (options.authorized_keys_command != NULL &&
1826             strcasecmp(options.authorized_keys_command, "none") != 0))
1827                 fatal("AuthorizedKeysCommand set without "
1828                     "AuthorizedKeysCommandUser");
1829         if (options.authorized_principals_command_user == NULL &&
1830             (options.authorized_principals_command != NULL &&
1831             strcasecmp(options.authorized_principals_command, "none") != 0))
1832                 fatal("AuthorizedPrincipalsCommand set without "
1833                     "AuthorizedPrincipalsCommandUser");
1834
1835         /*
1836          * Check whether there is any path through configured auth methods.
1837          * Unfortunately it is not possible to verify this generally before
1838          * daemonisation in the presence of Match block, but this catches
1839          * and warns for trivial misconfigurations that could break login.
1840          */
1841         if (options.num_auth_methods != 0) {
1842                 for (i = 0; i < options.num_auth_methods; i++) {
1843                         if (auth2_methods_valid(options.auth_methods[i],
1844                             1) == 0)
1845                                 break;
1846                 }
1847                 if (i >= options.num_auth_methods)
1848                         fatal("AuthenticationMethods cannot be satisfied by "
1849                             "enabled authentication methods");
1850         }
1851
1852         /* Check that there are no remaining arguments. */
1853         if (optind < ac) {
1854                 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1855                 exit(1);
1856         }
1857
1858         debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
1859
1860         /* Store privilege separation user for later use if required. */
1861         privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
1862         if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1863                 if (privsep_chroot || options.kerberos_authentication)
1864                         fatal("Privilege separation user %s does not exist",
1865                             SSH_PRIVSEP_USER);
1866         } else {
1867                 privsep_pw = pwcopy(privsep_pw);
1868                 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
1869                 privsep_pw->pw_passwd = xstrdup("*");
1870         }
1871         endpwent();
1872
1873         /* load host keys */
1874         sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1875             sizeof(struct sshkey *));
1876         sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1877             sizeof(struct sshkey *));
1878
1879         if (options.host_key_agent) {
1880                 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1881                         setenv(SSH_AUTHSOCKET_ENV_NAME,
1882                             options.host_key_agent, 1);
1883                 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1884                         have_agent = 1;
1885                 else
1886                         error_r(r, "Could not connect to agent \"%s\"",
1887                             options.host_key_agent);
1888         }
1889
1890         for (i = 0; i < options.num_host_key_files; i++) {
1891                 int ll = options.host_key_file_userprovided[i] ?
1892                     SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1;
1893
1894                 if (options.host_key_files[i] == NULL)
1895                         continue;
1896                 if ((r = sshkey_load_private(options.host_key_files[i], "",
1897                     &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1898                         do_log2_r(r, ll, "Unable to load host key \"%s\"",
1899                             options.host_key_files[i]);
1900                 if (sshkey_is_sk(key) &&
1901                     key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
1902                         debug("host key %s requires user presence, ignoring",
1903                             options.host_key_files[i]);
1904                         key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD;
1905                 }
1906                 if (r == 0 && key != NULL &&
1907                     (r = sshkey_shield_private(key)) != 0) {
1908                         do_log2_r(r, ll, "Unable to shield host key \"%s\"",
1909                             options.host_key_files[i]);
1910                         sshkey_free(key);
1911                         key = NULL;
1912                 }
1913                 if ((r = sshkey_load_public(options.host_key_files[i],
1914                     &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1915                         do_log2_r(r, ll, "Unable to load host key \"%s\"",
1916                             options.host_key_files[i]);
1917                 if (pubkey != NULL && key != NULL) {
1918                         if (!sshkey_equal(pubkey, key)) {
1919                                 error("Public key for %s does not match "
1920                                     "private key", options.host_key_files[i]);
1921                                 sshkey_free(pubkey);
1922                                 pubkey = NULL;
1923                         }
1924                 }
1925                 if (pubkey == NULL && key != NULL) {
1926                         if ((r = sshkey_from_private(key, &pubkey)) != 0)
1927                                 fatal_r(r, "Could not demote key: \"%s\"",
1928                                     options.host_key_files[i]);
1929                 }
1930                 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey,
1931                     options.required_rsa_size)) != 0) {
1932                         error_fr(r, "Host key %s", options.host_key_files[i]);
1933                         sshkey_free(pubkey);
1934                         sshkey_free(key);
1935                         continue;
1936                 }
1937                 sensitive_data.host_keys[i] = key;
1938                 sensitive_data.host_pubkeys[i] = pubkey;
1939
1940                 if (key == NULL && pubkey != NULL && have_agent) {
1941                         debug("will rely on agent for hostkey %s",
1942                             options.host_key_files[i]);
1943                         keytype = pubkey->type;
1944                 } else if (key != NULL) {
1945                         keytype = key->type;
1946                         accumulate_host_timing_secret(cfg, key);
1947                 } else {
1948                         do_log2(ll, "Unable to load host key: %s",
1949                             options.host_key_files[i]);
1950                         sensitive_data.host_keys[i] = NULL;
1951                         sensitive_data.host_pubkeys[i] = NULL;
1952                         continue;
1953                 }
1954
1955                 switch (keytype) {
1956                 case KEY_RSA:
1957                 case KEY_DSA:
1958                 case KEY_ECDSA:
1959                 case KEY_ED25519:
1960                 case KEY_ECDSA_SK:
1961                 case KEY_ED25519_SK:
1962                 case KEY_XMSS:
1963                         if (have_agent || key != NULL)
1964                                 sensitive_data.have_ssh2_key = 1;
1965                         break;
1966                 }
1967                 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1968                     SSH_FP_DEFAULT)) == NULL)
1969                         fatal("sshkey_fingerprint failed");
1970                 debug("%s host key #%d: %s %s",
1971                     key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1972                 free(fp);
1973         }
1974         accumulate_host_timing_secret(cfg, NULL);
1975         if (!sensitive_data.have_ssh2_key) {
1976                 logit("sshd: no hostkeys available -- exiting.");
1977                 exit(1);
1978         }
1979
1980         /*
1981          * Load certificates. They are stored in an array at identical
1982          * indices to the public keys that they relate to.
1983          */
1984         sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1985             sizeof(struct sshkey *));
1986         for (i = 0; i < options.num_host_key_files; i++)
1987                 sensitive_data.host_certificates[i] = NULL;
1988
1989         for (i = 0; i < options.num_host_cert_files; i++) {
1990                 if (options.host_cert_files[i] == NULL)
1991                         continue;
1992                 if ((r = sshkey_load_public(options.host_cert_files[i],
1993                     &key, NULL)) != 0) {
1994                         error_r(r, "Could not load host certificate \"%s\"",
1995                             options.host_cert_files[i]);
1996                         continue;
1997                 }
1998                 if (!sshkey_is_cert(key)) {
1999                         error("Certificate file is not a certificate: %s",
2000                             options.host_cert_files[i]);
2001                         sshkey_free(key);
2002                         continue;
2003                 }
2004                 /* Find matching private key */
2005                 for (j = 0; j < options.num_host_key_files; j++) {
2006                         if (sshkey_equal_public(key,
2007                             sensitive_data.host_pubkeys[j])) {
2008                                 sensitive_data.host_certificates[j] = key;
2009                                 break;
2010                         }
2011                 }
2012                 if (j >= options.num_host_key_files) {
2013                         error("No matching private key for certificate: %s",
2014                             options.host_cert_files[i]);
2015                         sshkey_free(key);
2016                         continue;
2017                 }
2018                 sensitive_data.host_certificates[j] = key;
2019                 debug("host certificate: #%u type %d %s", j, key->type,
2020                     sshkey_type(key));
2021         }
2022
2023         if (privsep_chroot) {
2024                 struct stat st;
2025
2026                 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
2027                     (S_ISDIR(st.st_mode) == 0))
2028                         fatal("Missing privilege separation directory: %s",
2029                             _PATH_PRIVSEP_CHROOT_DIR);
2030
2031 #ifdef HAVE_CYGWIN
2032                 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
2033                     (st.st_uid != getuid () ||
2034                     (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
2035 #else
2036                 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
2037 #endif
2038                         fatal("%s must be owned by root and not group or "
2039                             "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
2040         }
2041
2042         if (test_flag > 1) {
2043                 /*
2044                  * If no connection info was provided by -C then use
2045                  * use a blank one that will cause no predicate to match.
2046                  */
2047                 if (connection_info == NULL)
2048                         connection_info = get_connection_info(ssh, 0, 0);
2049                 connection_info->test = 1;
2050                 parse_server_match_config(&options, &includes, connection_info);
2051                 dump_config(&options);
2052         }
2053
2054         /* Configuration looks good, so exit if in test mode. */
2055         if (test_flag)
2056                 exit(0);
2057
2058         /*
2059          * Clear out any supplemental groups we may have inherited.  This
2060          * prevents inadvertent creation of files with bad modes (in the
2061          * portable version at least, it's certainly possible for PAM
2062          * to create a file, and we can't control the code in every
2063          * module which might be used).
2064          */
2065         if (setgroups(0, NULL) < 0)
2066                 debug("setgroups() failed: %.200s", strerror(errno));
2067
2068         if (rexec_flag) {
2069                 if (rexec_argc < 0)
2070                         fatal("rexec_argc %d < 0", rexec_argc);
2071                 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
2072                 for (i = 0; i < (u_int)rexec_argc; i++) {
2073                         debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
2074                         rexec_argv[i] = saved_argv[i];
2075                 }
2076                 rexec_argv[rexec_argc] = "-R";
2077                 rexec_argv[rexec_argc + 1] = NULL;
2078         }
2079         listener_proctitle = prepare_proctitle(ac, av);
2080
2081         /* Ensure that umask disallows at least group and world write */
2082         new_umask = umask(0077) | 0022;
2083         (void) umask(new_umask);
2084
2085         /* Initialize the log (it is reinitialized below in case we forked). */
2086         if (debug_flag && (!inetd_flag || rexeced_flag))
2087                 log_stderr = 1;
2088         log_init(__progname, options.log_level,
2089             options.log_facility, log_stderr);
2090         for (i = 0; i < options.num_log_verbose; i++)
2091                 log_verbose_add(options.log_verbose[i]);
2092
2093         /*
2094          * If not in debugging mode, not started from inetd and not already
2095          * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
2096          * terminal, and fork.  The original process exits.
2097          */
2098         already_daemon = daemonized();
2099         if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
2100
2101                 if (daemon(0, 0) == -1)
2102                         fatal("daemon() failed: %.200s", strerror(errno));
2103
2104                 disconnect_controlling_tty();
2105         }
2106         /* Reinitialize the log (because of the fork above). */
2107         log_init(__progname, options.log_level, options.log_facility, log_stderr);
2108
2109 #ifdef LIBWRAP
2110         /*
2111          * We log refusals ourselves.  However, libwrap will report
2112          * syntax errors in hosts.allow via syslog(3).
2113          */
2114         allow_severity = options.log_facility|LOG_INFO;
2115         deny_severity = options.log_facility|LOG_WARNING;
2116 #endif
2117         /* Avoid killing the process in high-pressure swapping environments. */
2118         if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
2119                 debug("madvise(): %.200s", strerror(errno));
2120
2121         /*
2122          * Chdir to the root directory so that the current disk can be
2123          * unmounted if desired.
2124          */
2125         if (chdir("/") == -1)
2126                 error("chdir(\"/\"): %s", strerror(errno));
2127
2128         /* ignore SIGPIPE */
2129         ssh_signal(SIGPIPE, SIG_IGN);
2130
2131         /* Get a connection, either from inetd or a listening TCP socket */
2132         if (inetd_flag) {
2133                 server_accept_inetd(&sock_in, &sock_out);
2134         } else {
2135                 platform_pre_listen();
2136                 server_listen();
2137
2138                 ssh_signal(SIGHUP, sighup_handler);
2139                 ssh_signal(SIGCHLD, main_sigchld_handler);
2140                 ssh_signal(SIGTERM, sigterm_handler);
2141                 ssh_signal(SIGQUIT, sigterm_handler);
2142
2143                 /*
2144                  * Write out the pid file after the sigterm handler
2145                  * is setup and the listen sockets are bound
2146                  */
2147                 if (options.pid_file != NULL && !debug_flag) {
2148                         FILE *f = fopen(options.pid_file, "w");
2149
2150                         if (f == NULL) {
2151                                 error("Couldn't create pid file \"%s\": %s",
2152                                     options.pid_file, strerror(errno));
2153                         } else {
2154                                 fprintf(f, "%ld\n", (long) getpid());
2155                                 fclose(f);
2156                         }
2157                 }
2158
2159                 /* Accept a connection and return in a forked child */
2160                 server_accept_loop(&sock_in, &sock_out,
2161                     &newsock, config_s);
2162         }
2163
2164         /* This is the child processing a new connection. */
2165         setproctitle("%s", "[accepted]");
2166
2167         /*
2168          * Create a new session and process group since the 4.4BSD
2169          * setlogin() affects the entire process group.  We don't
2170          * want the child to be able to affect the parent.
2171          */
2172         if (!debug_flag && !inetd_flag && setsid() == -1)
2173                 error("setsid: %.100s", strerror(errno));
2174
2175         if (rexec_flag) {
2176                 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
2177                     sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2178                 dup2(newsock, STDIN_FILENO);
2179                 dup2(STDIN_FILENO, STDOUT_FILENO);
2180                 if (startup_pipe == -1)
2181                         close(REEXEC_STARTUP_PIPE_FD);
2182                 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
2183                         dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
2184                         close(startup_pipe);
2185                         startup_pipe = REEXEC_STARTUP_PIPE_FD;
2186                 }
2187
2188                 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
2189                 close(config_s[1]);
2190
2191                 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */
2192                 execv(rexec_argv[0], rexec_argv);
2193
2194                 /* Reexec has failed, fall back and continue */
2195                 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
2196                 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
2197                 log_init(__progname, options.log_level,
2198                     options.log_facility, log_stderr);
2199
2200                 /* Clean up fds */
2201                 close(REEXEC_CONFIG_PASS_FD);
2202                 newsock = sock_out = sock_in = dup(STDIN_FILENO);
2203                 if (stdfd_devnull(1, 1, 0) == -1)
2204                         error_f("stdfd_devnull failed");
2205                 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
2206                     sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2207         }
2208
2209         /* Executed child processes don't need these. */
2210         fcntl(sock_out, F_SETFD, FD_CLOEXEC);
2211         fcntl(sock_in, F_SETFD, FD_CLOEXEC);
2212
2213         /* We will not restart on SIGHUP since it no longer makes sense. */
2214         ssh_signal(SIGALRM, SIG_DFL);
2215         ssh_signal(SIGHUP, SIG_DFL);
2216         ssh_signal(SIGTERM, SIG_DFL);
2217         ssh_signal(SIGQUIT, SIG_DFL);
2218         ssh_signal(SIGCHLD, SIG_DFL);
2219         ssh_signal(SIGINT, SIG_DFL);
2220
2221 #ifdef __FreeBSD__
2222         /*
2223          * Initialize the resolver.  This may not happen automatically
2224          * before privsep chroot().
2225          */
2226         if ((_res.options & RES_INIT) == 0) {
2227                 debug("res_init()");
2228                 res_init();
2229         }
2230 #ifdef GSSAPI
2231         /*
2232          * Force GSS-API to parse its configuration and load any
2233          * mechanism plugins.
2234          */
2235         {
2236                 gss_OID_set mechs;
2237                 OM_uint32 minor_status;
2238                 gss_indicate_mechs(&minor_status, &mechs);
2239                 gss_release_oid_set(&minor_status, &mechs);
2240         }
2241 #endif
2242 #endif
2243
2244         /*
2245          * Register our connection.  This turns encryption off because we do
2246          * not have a key.
2247          */
2248         if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL)
2249                 fatal("Unable to create connection");
2250         the_active_state = ssh;
2251         ssh_packet_set_server(ssh);
2252
2253         check_ip_options(ssh);
2254
2255         /* Prepare the channels layer */
2256         channel_init_channels(ssh);
2257         channel_set_af(ssh, options.address_family);
2258         process_permitopen(ssh, &options);
2259
2260         /* Set SO_KEEPALIVE if requested. */
2261         if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) &&
2262             setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1)
2263                 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
2264
2265         if ((remote_port = ssh_remote_port(ssh)) < 0) {
2266                 debug("ssh_remote_port failed");
2267                 cleanup_exit(255);
2268         }
2269
2270         if (options.routing_domain != NULL)
2271                 set_process_rdomain(ssh, options.routing_domain);
2272
2273         /*
2274          * The rest of the code depends on the fact that
2275          * ssh_remote_ipaddr() caches the remote ip, even if
2276          * the socket goes away.
2277          */
2278         remote_ip = ssh_remote_ipaddr(ssh);
2279
2280 #ifdef HAVE_LOGIN_CAP
2281         /* Also caches remote hostname for sandboxed child. */
2282         auth_get_canonical_hostname(ssh, options.use_dns);
2283 #endif
2284
2285 #ifdef SSH_AUDIT_EVENTS
2286         audit_connection_from(remote_ip, remote_port);
2287 #endif
2288
2289         rdomain = ssh_packet_rdomain_in(ssh);
2290
2291         /* Log the connection. */
2292         laddr = get_local_ipaddr(sock_in);
2293         verbose("Connection from %s port %d on %s port %d%s%s%s",
2294             remote_ip, remote_port, laddr,  ssh_local_port(ssh),
2295             rdomain == NULL ? "" : " rdomain \"",
2296             rdomain == NULL ? "" : rdomain,
2297             rdomain == NULL ? "" : "\"");
2298         free(laddr);
2299
2300         /*
2301          * We don't want to listen forever unless the other side
2302          * successfully authenticates itself.  So we set up an alarm which is
2303          * cleared after successful authentication.  A limit of zero
2304          * indicates no limit. Note that we don't set the alarm in debugging
2305          * mode; it is just annoying to have the server exit just when you
2306          * are about to discover the bug.
2307          */
2308         ssh_signal(SIGALRM, grace_alarm_handler);
2309         if (!debug_flag)
2310                 alarm(options.login_grace_time);
2311
2312         if ((r = kex_exchange_identification(ssh, -1,
2313             options.version_addendum)) != 0)
2314                 sshpkt_fatal(ssh, r, "banner exchange");
2315
2316         ssh_packet_set_nonblocking(ssh);
2317
2318         /* allocate authentication context */
2319         authctxt = xcalloc(1, sizeof(*authctxt));
2320         ssh->authctxt = authctxt;
2321
2322         authctxt->loginmsg = loginmsg;
2323
2324         /* XXX global for cleanup, access from other modules */
2325         the_authctxt = authctxt;
2326
2327         /* Set default key authentication options */
2328         if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
2329                 fatal("allocation failed");
2330
2331         /* prepare buffer to collect messages to display to user after login */
2332         if ((loginmsg = sshbuf_new()) == NULL)
2333                 fatal_f("sshbuf_new failed");
2334         auth_debug_reset();
2335
2336         BLACKLIST_INIT();
2337
2338         if (use_privsep) {
2339                 if (privsep_preauth(ssh) == 1)
2340                         goto authenticated;
2341         } else if (have_agent) {
2342                 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2343                         error_r(r, "Unable to get agent socket");
2344                         have_agent = 0;
2345                 }
2346         }
2347
2348         /* perform the key exchange */
2349         /* authenticate user and start session */
2350         do_ssh2_kex(ssh);
2351         do_authentication2(ssh);
2352
2353         /*
2354          * If we use privilege separation, the unprivileged child transfers
2355          * the current keystate and exits
2356          */
2357         if (use_privsep) {
2358                 mm_send_keystate(ssh, pmonitor);
2359                 ssh_packet_clear_keys(ssh);
2360                 exit(0);
2361         }
2362
2363  authenticated:
2364         /*
2365          * Cancel the alarm we set to limit the time taken for
2366          * authentication.
2367          */
2368         alarm(0);
2369         ssh_signal(SIGALRM, SIG_DFL);
2370         authctxt->authenticated = 1;
2371         if (startup_pipe != -1) {
2372                 close(startup_pipe);
2373                 startup_pipe = -1;
2374         }
2375
2376 #ifdef SSH_AUDIT_EVENTS
2377         audit_event(ssh, SSH_AUTH_SUCCESS);
2378 #endif
2379
2380 #ifdef GSSAPI
2381         if (options.gss_authentication) {
2382                 temporarily_use_uid(authctxt->pw);
2383                 ssh_gssapi_storecreds();
2384                 restore_uid();
2385         }
2386 #endif
2387 #ifdef USE_PAM
2388         if (options.use_pam) {
2389                 do_pam_setcred(1);
2390                 do_pam_session(ssh);
2391         }
2392 #endif
2393
2394         /*
2395          * In privilege separation, we fork another child and prepare
2396          * file descriptor passing.
2397          */
2398         if (use_privsep) {
2399                 privsep_postauth(ssh, authctxt);
2400                 /* the monitor process [priv] will not return */
2401         }
2402
2403         ssh_packet_set_timeout(ssh, options.client_alive_interval,
2404             options.client_alive_count_max);
2405
2406         /* Try to send all our hostkeys to the client */
2407         notify_hostkeys(ssh);
2408
2409         /* Start session. */
2410         do_authenticated(ssh, authctxt);
2411
2412         /* The connection has been terminated. */
2413         ssh_packet_get_bytes(ssh, &ibytes, &obytes);
2414         verbose("Transferred: sent %llu, received %llu bytes",
2415             (unsigned long long)obytes, (unsigned long long)ibytes);
2416
2417         verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2418
2419 #ifdef USE_PAM
2420         if (options.use_pam)
2421                 finish_pam();
2422 #endif /* USE_PAM */
2423
2424 #ifdef SSH_AUDIT_EVENTS
2425         PRIVSEP(audit_event(ssh, SSH_CONNECTION_CLOSE));
2426 #endif
2427
2428         ssh_packet_close(ssh);
2429
2430         if (use_privsep)
2431                 mm_terminate();
2432
2433         exit(0);
2434 }
2435
2436 int
2437 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
2438     struct sshkey *pubkey, u_char **signature, size_t *slenp,
2439     const u_char *data, size_t dlen, const char *alg)
2440 {
2441         int r;
2442
2443         if (use_privsep) {
2444                 if (privkey) {
2445                         if (mm_sshkey_sign(ssh, privkey, signature, slenp,
2446                             data, dlen, alg, options.sk_provider, NULL,
2447                             ssh->compat) < 0)
2448                                 fatal_f("privkey sign failed");
2449                 } else {
2450                         if (mm_sshkey_sign(ssh, pubkey, signature, slenp,
2451                             data, dlen, alg, options.sk_provider, NULL,
2452                             ssh->compat) < 0)
2453                                 fatal_f("pubkey sign failed");
2454                 }
2455         } else {
2456                 if (privkey) {
2457                         if (sshkey_sign(privkey, signature, slenp, data, dlen,
2458                             alg, options.sk_provider, NULL, ssh->compat) < 0)
2459                                 fatal_f("privkey sign failed");
2460                 } else {
2461                         if ((r = ssh_agent_sign(auth_sock, pubkey,
2462                             signature, slenp, data, dlen, alg,
2463                             ssh->compat)) != 0) {
2464                                 fatal_fr(r, "agent sign failed");
2465                         }
2466                 }
2467         }
2468         return 0;
2469 }
2470
2471 /* SSH2 key exchange */
2472 static void
2473 do_ssh2_kex(struct ssh *ssh)
2474 {
2475         char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2476         struct kex *kex;
2477         char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL;
2478         int r;
2479
2480         myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh,
2481             options.kex_algorithms);
2482         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2483             myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc =
2484             compat_cipher_proposal(ssh, options.ciphers);
2485         myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2486             myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2487
2488         if (options.compression == COMP_NONE) {
2489                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2490                     myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2491         }
2492
2493         if (options.rekey_limit || options.rekey_interval)
2494                 ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
2495                     options.rekey_interval);
2496
2497         myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey =
2498            compat_pkalg_proposal(ssh, list_hostkey_types());
2499
2500         /* start key exchange */
2501         if ((r = kex_setup(ssh, myproposal)) != 0)
2502                 fatal_r(r, "kex_setup");
2503         kex = ssh->kex;
2504 #ifdef WITH_OPENSSL
2505         kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
2506         kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
2507         kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
2508         kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
2509         kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
2510         kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2511         kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2512 # ifdef OPENSSL_HAS_ECC
2513         kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
2514 # endif
2515 #endif
2516         kex->kex[KEX_C25519_SHA256] = kex_gen_server;
2517         kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
2518         kex->load_host_public_key=&get_hostkey_public_by_type;
2519         kex->load_host_private_key=&get_hostkey_private_by_type;
2520         kex->host_key_index=&get_hostkey_index;
2521         kex->sign = sshd_hostkey_sign;
2522
2523         ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done);
2524
2525 #ifdef DEBUG_KEXDH
2526         /* send 1st encrypted/maced/compressed message */
2527         if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
2528             (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
2529             (r = sshpkt_send(ssh)) != 0 ||
2530             (r = ssh_packet_write_wait(ssh)) != 0)
2531                 fatal_fr(r, "send test");
2532 #endif
2533         free(prop_kex);
2534         free(prop_enc);
2535         free(prop_hostkey);
2536         debug("KEX done");
2537 }
2538
2539 /* server specific fatal cleanup */
2540 void
2541 cleanup_exit(int i)
2542 {
2543         if (the_active_state != NULL && the_authctxt != NULL) {
2544                 do_cleanup(the_active_state, the_authctxt);
2545                 if (use_privsep && privsep_is_preauth &&
2546                     pmonitor != NULL && pmonitor->m_pid > 1) {
2547                         debug("Killing privsep child %d", pmonitor->m_pid);
2548                         if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2549                             errno != ESRCH) {
2550                                 error_f("kill(%d): %s", pmonitor->m_pid,
2551                                     strerror(errno));
2552                         }
2553                 }
2554         }
2555 #ifdef SSH_AUDIT_EVENTS
2556         /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2557         if (the_active_state != NULL && (!use_privsep || mm_is_monitor()))
2558                 audit_event(the_active_state, SSH_CONNECTION_ABANDON);
2559 #endif
2560         _exit(i);
2561 }