Adding upstream version 1:7.9p1.upstream/1%7.9p1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2353 insertions, 0 deletions

diff --git a/sshd.c b/sshd.c
new file mode 100644
index 0000000..ba26287
--- /dev/null
+++ b/sshd.c
@@ -0,0 +1,2353 @@
+/* $OpenBSD: sshd.c,v 1.516 2018/09/21 12:23:17 djm Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * This program is the ssh daemon.  It listens for connections from clients,
+ * and performs authentication, executes use commands or shell, and forwards
+ * information to/from the application to the user client over an encrypted
+ * connection.  This can also handle forwarding of X11, TCP/IP, and
+ * authentication agent connections.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ *
+ * SSH2 implementation:
+ * Privilege Separation:
+ *
+ * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2002 Niels Provos.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#ifdef HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+#include "openbsd-compat/sys-tree.h"
+#include "openbsd-compat/sys-queue.h"
+#include <sys/wait.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <netdb.h>
+#ifdef HAVE_PATHS_H
+#include <paths.h>
+#endif
+#include <grp.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+
+#ifdef WITH_OPENSSL
+#include <openssl/dh.h>
+#include <openssl/bn.h>
+#include <openssl/rand.h>
+#include "openbsd-compat/openssl-compat.h"
+#endif
+
+#ifdef HAVE_SECUREWARE
+#include <sys/security.h>
+#include <prot.h>
+#endif
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "ssh2.h"
+#include "sshpty.h"
+#include "packet.h"
+#include "log.h"
+#include "sshbuf.h"
+#include "misc.h"
+#include "match.h"
+#include "servconf.h"
+#include "uidswap.h"
+#include "compat.h"
+#include "cipher.h"
+#include "digest.h"
+#include "sshkey.h"
+#include "kex.h"
+#include "myproposal.h"
+#include "authfile.h"
+#include "pathnames.h"
+#include "atomicio.h"
+#include "canohost.h"
+#include "hostfile.h"
+#include "auth.h"
+#include "authfd.h"
+#include "msg.h"
+#include "dispatch.h"
+#include "channels.h"
+#include "session.h"
+#include "monitor.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "monitor_wrap.h"
+#include "ssh-sandbox.h"
+#include "auth-options.h"
+#include "version.h"
+#include "ssherr.h"
+
+/* Re-exec fds */
+#define REEXEC_DEVCRYPTO_RESERVED_FD	(STDERR_FILENO + 1)
+#define REEXEC_STARTUP_PIPE_FD		(STDERR_FILENO + 2)
+#define REEXEC_CONFIG_PASS_FD		(STDERR_FILENO + 3)
+#define REEXEC_MIN_FREE_FD		(STDERR_FILENO + 4)
+
+extern char *__progname;
+
+/* Server configuration options. */
+ServerOptions options;
+
+/* Name of the server configuration file. */
+char *config_file_name = _PATH_SERVER_CONFIG_FILE;
+
+/*
+ * Debug mode flag.  This can be set on the command line.  If debug
+ * mode is enabled, extra debugging output will be sent to the system
+ * log, the daemon will not go to background, and will exit after processing
+ * the first connection.
+ */
+int debug_flag = 0;
+
+/*
+ * Indicating that the daemon should only test the configuration and keys.
+ * If test_flag > 1 ("-T" flag), then sshd will also dump the effective
+ * configuration, optionally using connection information provided by the
+ * "-C" flag.
+ */
+int test_flag = 0;
+
+/* Flag indicating that the daemon is being started from inetd. */
+int inetd_flag = 0;
+
+/* Flag indicating that sshd should not detach and become a daemon. */
+int no_daemon_flag = 0;
+
+/* debug goes to stderr unless inetd_flag is set */
+int log_stderr = 0;
+
+/* Saved arguments to main(). */
+char **saved_argv;
+int saved_argc;
+
+/* re-exec */
+int rexeced_flag = 0;
+int rexec_flag = 1;
+int rexec_argc = 0;
+char **rexec_argv;
+
+/*
+ * The sockets that the server is listening; this is used in the SIGHUP
+ * signal handler.
+ */
+#define	MAX_LISTEN_SOCKS	16
+int listen_socks[MAX_LISTEN_SOCKS];
+int num_listen_socks = 0;
+
+/*
+ * the client's version string, passed by sshd2 in compat mode. if != NULL,
+ * sshd will skip the version-number exchange
+ */
+char *client_version_string = NULL;
+char *server_version_string = NULL;
+
+/* Daemon's agent connection */
+int auth_sock = -1;
+int have_agent = 0;
+
+/*
+ * Any really sensitive data in the application is contained in this
+ * structure. The idea is that this structure could be locked into memory so
+ * that the pages do not get written into swap.  However, there are some
+ * problems. The private key contains BIGNUMs, and we do not (in principle)
+ * have access to the internals of them, and locking just the structure is
+ * not very useful.  Currently, memory locking is not implemented.
+ */
+struct {
+	struct sshkey	**host_keys;		/* all private host keys */
+	struct sshkey	**host_pubkeys;		/* all public host keys */
+	struct sshkey	**host_certificates;	/* all public host certificates */
+	int		have_ssh2_key;
+} sensitive_data;
+
+/* This is set to true when a signal is received. */
+static volatile sig_atomic_t received_sighup = 0;
+static volatile sig_atomic_t received_sigterm = 0;
+
+/* session identifier, used by RSA-auth */
+u_char session_id[16];
+
+/* same for ssh2 */
+u_char *session_id2 = NULL;
+u_int session_id2_len = 0;
+
+/* record remote hostname or ip */
+u_int utmp_len = HOST_NAME_MAX+1;
+
+/* options.max_startup sized array of fd ints */
+int *startup_pipes = NULL;
+int startup_pipe;		/* in child */
+
+/* variables used for privilege separation */
+int use_privsep = -1;
+struct monitor *pmonitor = NULL;
+int privsep_is_preauth = 1;
+static int privsep_chroot = 1;
+
+/* global authentication context */
+Authctxt *the_authctxt = NULL;
+
+/* global key/cert auth options. XXX move to permanent ssh->authctxt? */
+struct sshauthopt *auth_opts = NULL;
+
+/* sshd_config buffer */
+struct sshbuf *cfg;
+
+/* message to be displayed after login */
+struct sshbuf *loginmsg;
+
+/* Unprivileged user */
+struct passwd *privsep_pw = NULL;
+
+/* Prototypes for various functions defined later in this file. */
+void destroy_sensitive_data(void);
+void demote_sensitive_data(void);
+static void do_ssh2_kex(void);
+
+/*
+ * Close all listening sockets
+ */
+static void
+close_listen_socks(void)
+{
+	int i;
+
+	for (i = 0; i < num_listen_socks; i++)
+		close(listen_socks[i]);
+	num_listen_socks = -1;
+}
+
+static void
+close_startup_pipes(void)
+{
+	int i;
+
+	if (startup_pipes)
+		for (i = 0; i < options.max_startups; i++)
+			if (startup_pipes[i] != -1)
+				close(startup_pipes[i]);
+}
+
+/*
+ * Signal handler for SIGHUP.  Sshd execs itself when it receives SIGHUP;
+ * the effect is to reread the configuration file (and to regenerate
+ * the server key).
+ */
+
+/*ARGSUSED*/
+static void
+sighup_handler(int sig)
+{
+	int save_errno = errno;
+
+	received_sighup = 1;
+	errno = save_errno;
+}
+
+/*
+ * Called from the main program after receiving SIGHUP.
+ * Restarts the server.
+ */
+static void
+sighup_restart(void)
+{
+	logit("Received SIGHUP; restarting.");
+	if (options.pid_file != NULL)
+		unlink(options.pid_file);
+	platform_pre_restart();
+	close_listen_socks();
+	close_startup_pipes();
+	alarm(0);  /* alarm timer persists across exec */
+	signal(SIGHUP, SIG_IGN); /* will be restored after exec */
+	execv(saved_argv[0], saved_argv);
+	logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
+	    strerror(errno));
+	exit(1);
+}
+
+/*
+ * Generic signal handler for terminating signals in the master daemon.
+ */
+/*ARGSUSED*/
+static void
+sigterm_handler(int sig)
+{
+	received_sigterm = sig;
+}
+
+/*
+ * SIGCHLD handler.  This is called whenever a child dies.  This will then
+ * reap any zombies left by exited children.
+ */
+/*ARGSUSED*/
+static void
+main_sigchld_handler(int sig)
+{
+	int save_errno = errno;
+	pid_t pid;
+	int status;
+
+	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
+	    (pid < 0 && errno == EINTR))
+		;
+	errno = save_errno;
+}
+
+/*
+ * Signal handler for the alarm after the login grace period has expired.
+ */
+/*ARGSUSED*/
+static void
+grace_alarm_handler(int sig)
+{
+	if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
+		kill(pmonitor->m_pid, SIGALRM);
+
+	/*
+	 * Try to kill any processes that we have spawned, E.g. authorized
+	 * keys command helpers.
+	 */
+	if (getpgid(0) == getpid()) {
+		signal(SIGTERM, SIG_IGN);
+		kill(0, SIGTERM);
+	}
+
+	/* Log error and exit. */
+	sigdie("Timeout before authentication for %s port %d",
+	    ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
+}
+
+static void
+sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
+{
+	u_int i;
+	int remote_major, remote_minor;
+	char *s;
+	char buf[256];			/* Must not be larger than remote_version. */
+	char remote_version[256];	/* Must be at least as big as buf. */
+
+	xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
+	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
+	    *options.version_addendum == '\0' ? "" : " ",
+	    options.version_addendum);
+
+	/* Send our protocol version identification. */
+	if (atomicio(vwrite, sock_out, server_version_string,
+	    strlen(server_version_string))
+	    != strlen(server_version_string)) {
+		logit("Could not write ident string to %s port %d",
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+		cleanup_exit(255);
+	}
+
+	/* Read other sides version identification. */
+	memset(buf, 0, sizeof(buf));
+	for (i = 0; i < sizeof(buf) - 1; i++) {
+		if (atomicio(read, sock_in, &buf[i], 1) != 1) {
+			logit("Did not receive identification string "
+			    "from %s port %d",
+			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+			cleanup_exit(255);
+		}
+		if (buf[i] == '\r') {
+			buf[i] = 0;
+			/* Kludge for F-Secure Macintosh < 1.0.2 */
+			if (i == 12 &&
+			    strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
+				break;
+			continue;
+		}
+		if (buf[i] == '\n') {
+			buf[i] = 0;
+			break;
+		}
+	}
+	buf[sizeof(buf) - 1] = 0;
+	client_version_string = xstrdup(buf);
+
+	/*
+	 * Check that the versions match.  In future this might accept
+	 * several versions and set appropriate flags to handle them.
+	 */
+	if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
+	    &remote_major, &remote_minor, remote_version) != 3) {
+		s = "Protocol mismatch.\n";
+		(void) atomicio(vwrite, sock_out, s, strlen(s));
+		logit("Bad protocol version identification '%.100s' "
+		    "from %s port %d", client_version_string,
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+		close(sock_in);
+		close(sock_out);
+		cleanup_exit(255);
+	}
+	debug("Client protocol version %d.%d; client software version %.100s",
+	    remote_major, remote_minor, remote_version);
+
+	ssh->compat = compat_datafellows(remote_version);
+
+	if ((ssh->compat & SSH_BUG_PROBE) != 0) {
+		logit("probed from %s port %d with %s.  Don't panic.",
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+		    client_version_string);
+		cleanup_exit(255);
+	}
+	if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
+		logit("scanned from %s port %d with %s.  Don't panic.",
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+		    client_version_string);
+		cleanup_exit(255);
+	}
+	if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
+		logit("Client version \"%.100s\" uses unsafe RSA signature "
+		    "scheme; disabling use of RSA keys", remote_version);
+	}
+
+	chop(server_version_string);
+	debug("Local version string %.200s", server_version_string);
+
+	if (remote_major != 2 &&
+	    !(remote_major == 1 && remote_minor == 99)) {
+		s = "Protocol major versions differ.\n";
+		(void) atomicio(vwrite, sock_out, s, strlen(s));
+		close(sock_in);
+		close(sock_out);
+		logit("Protocol major versions differ for %s port %d: "
+		    "%.200s vs. %.200s",
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+		    server_version_string, client_version_string);
+		cleanup_exit(255);
+	}
+}
+
+/* Destroy the host and server keys.  They will no longer be needed. */
+void
+destroy_sensitive_data(void)
+{
+	u_int i;
+
+	for (i = 0; i < options.num_host_key_files; i++) {
+		if (sensitive_data.host_keys[i]) {
+			sshkey_free(sensitive_data.host_keys[i]);
+			sensitive_data.host_keys[i] = NULL;
+		}
+		if (sensitive_data.host_certificates[i]) {
+			sshkey_free(sensitive_data.host_certificates[i]);
+			sensitive_data.host_certificates[i] = NULL;
+		}
+	}
+}
+
+/* Demote private to public keys for network child */
+void
+demote_sensitive_data(void)
+{
+	struct sshkey *tmp;
+	u_int i;
+	int r;
+
+	for (i = 0; i < options.num_host_key_files; i++) {
+		if (sensitive_data.host_keys[i]) {
+			if ((r = sshkey_from_private(
+			    sensitive_data.host_keys[i], &tmp)) != 0)
+				fatal("could not demote host %s key: %s",
+				    sshkey_type(sensitive_data.host_keys[i]),
+				    ssh_err(r));
+			sshkey_free(sensitive_data.host_keys[i]);
+			sensitive_data.host_keys[i] = tmp;
+		}
+		/* Certs do not need demotion */
+	}
+}
+
+static void
+reseed_prngs(void)
+{
+	u_int32_t rnd[256];
+
+#ifdef WITH_OPENSSL
+	RAND_poll();
+#endif
+	arc4random_stir(); /* noop on recent arc4random() implementations */
+	arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
+
+#ifdef WITH_OPENSSL
+	RAND_seed(rnd, sizeof(rnd));
+	/* give libcrypto a chance to notice the PID change */
+	if ((RAND_bytes((u_char *)rnd, 1)) != 1)
+		fatal("%s: RAND_bytes failed", __func__);
+#endif
+
+	explicit_bzero(rnd, sizeof(rnd));
+}
+
+static void
+privsep_preauth_child(void)
+{
+	gid_t gidset[1];
+
+	/* Enable challenge-response authentication for privilege separation */
+	privsep_challenge_enable();
+
+#ifdef GSSAPI
+	/* Cache supported mechanism OIDs for later use */
+	ssh_gssapi_prepare_supported_oids();
+#endif
+
+	reseed_prngs();
+
+	/* Demote the private keys to public keys. */
+	demote_sensitive_data();
+
+	/* Demote the child */
+	if (privsep_chroot) {
+		/* Change our root directory */
+		if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
+			fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
+			    strerror(errno));
+		if (chdir("/") == -1)
+			fatal("chdir(\"/\"): %s", strerror(errno));
+
+		/* Drop our privileges */
+		debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
+		    (u_int)privsep_pw->pw_gid);
+		gidset[0] = privsep_pw->pw_gid;
+		if (setgroups(1, gidset) < 0)
+			fatal("setgroups: %.100s", strerror(errno));
+		permanently_set_uid(privsep_pw);
+	}
+}
+
+static int
+privsep_preauth(Authctxt *authctxt)
+{
+	int status, r;
+	pid_t pid;
+	struct ssh_sandbox *box = NULL;
+
+	/* Set up unprivileged child process to deal with network data */
+	pmonitor = monitor_init();
+	/* Store a pointer to the kex for later rekeying */
+	pmonitor->m_pkex = &active_state->kex;
+
+	if (use_privsep == PRIVSEP_ON)
+		box = ssh_sandbox_init(pmonitor);
+	pid = fork();
+	if (pid == -1) {
+		fatal("fork of unprivileged child failed");
+	} else if (pid != 0) {
+		debug2("Network child is on pid %ld", (long)pid);
+
+		pmonitor->m_pid = pid;
+		if (have_agent) {
+			r = ssh_get_authentication_socket(&auth_sock);
+			if (r != 0) {
+				error("Could not get agent socket: %s",
+				    ssh_err(r));
+				have_agent = 0;
+			}
+		}
+		if (box != NULL)
+			ssh_sandbox_parent_preauth(box, pid);
+		monitor_child_preauth(authctxt, pmonitor);
+
+		/* Wait for the child's exit status */
+		while (waitpid(pid, &status, 0) < 0) {
+			if (errno == EINTR)
+				continue;
+			pmonitor->m_pid = -1;
+			fatal("%s: waitpid: %s", __func__, strerror(errno));
+		}
+		privsep_is_preauth = 0;
+		pmonitor->m_pid = -1;
+		if (WIFEXITED(status)) {
+			if (WEXITSTATUS(status) != 0)
+				fatal("%s: preauth child exited with status %d",
+				    __func__, WEXITSTATUS(status));
+		} else if (WIFSIGNALED(status))
+			fatal("%s: preauth child terminated by signal %d",
+			    __func__, WTERMSIG(status));
+		if (box != NULL)
+			ssh_sandbox_parent_finish(box);
+		return 1;
+	} else {
+		/* child */
+		close(pmonitor->m_sendfd);
+		close(pmonitor->m_log_recvfd);
+
+		/* Arrange for logging to be sent to the monitor */
+		set_log_handler(mm_log_handler, pmonitor);
+
+		privsep_preauth_child();
+		setproctitle("%s", "[net]");
+		if (box != NULL)
+			ssh_sandbox_child(box);
+
+		return 0;
+	}
+}
+
+static void
+privsep_postauth(Authctxt *authctxt)
+{
+#ifdef DISABLE_FD_PASSING
+	if (1) {
+#else
+	if (authctxt->pw->pw_uid == 0) {
+#endif
+		/* File descriptor passing is broken or root login */
+		use_privsep = 0;
+		goto skip;
+	}
+
+	/* New socket pair */
+	monitor_reinit(pmonitor);
+
+	pmonitor->m_pid = fork();
+	if (pmonitor->m_pid == -1)
+		fatal("fork of unprivileged child failed");
+	else if (pmonitor->m_pid != 0) {
+		verbose("User child is on pid %ld", (long)pmonitor->m_pid);
+		sshbuf_reset(loginmsg);
+		monitor_clear_keystate(pmonitor);
+		monitor_child_postauth(pmonitor);
+
+		/* NEVERREACHED */
+		exit(0);
+	}
+
+	/* child */
+
+	close(pmonitor->m_sendfd);
+	pmonitor->m_sendfd = -1;
+
+	/* Demote the private keys to public keys. */
+	demote_sensitive_data();
+
+	reseed_prngs();
+
+	/* Drop privileges */
+	do_setusercontext(authctxt->pw);
+
+ skip:
+	/* It is safe now to apply the key state */
+	monitor_apply_keystate(pmonitor);
+
+	/*
+	 * Tell the packet layer that authentication was successful, since
+	 * this information is not part of the key state.
+	 */
+	packet_set_authenticated();
+}
+
+static void
+append_hostkey_type(struct sshbuf *b, const char *s)
+{
+	int r;
+
+	if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
+		debug3("%s: %s key not permitted by HostkeyAlgorithms",
+		    __func__, s);
+		return;
+	}
+	if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
+		fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
+}
+
+static char *
+list_hostkey_types(void)
+{
+	struct sshbuf *b;
+	struct sshkey *key;
+	char *ret;
+	u_int i;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	for (i = 0; i < options.num_host_key_files; i++) {
+		key = sensitive_data.host_keys[i];
+		if (key == NULL)
+			key = sensitive_data.host_pubkeys[i];
+		if (key == NULL)
+			continue;
+		switch (key->type) {
+		case KEY_RSA:
+			/* for RSA we also support SHA2 signatures */
+			append_hostkey_type(b, "rsa-sha2-512");
+			append_hostkey_type(b, "rsa-sha2-256");
+			/* FALLTHROUGH */
+		case KEY_DSA:
+		case KEY_ECDSA:
+		case KEY_ED25519:
+		case KEY_XMSS:
+			append_hostkey_type(b, sshkey_ssh_name(key));
+			break;
+		}
+		/* If the private key has a cert peer, then list that too */
+		key = sensitive_data.host_certificates[i];
+		if (key == NULL)
+			continue;
+		switch (key->type) {
+		case KEY_RSA_CERT:
+			/* for RSA we also support SHA2 signatures */
+			append_hostkey_type(b,
+			    "rsa-sha2-512-cert-v01@openssh.com");
+			append_hostkey_type(b,
+			    "rsa-sha2-256-cert-v01@openssh.com");
+			/* FALLTHROUGH */
+		case KEY_DSA_CERT:
+		case KEY_ECDSA_CERT:
+		case KEY_ED25519_CERT:
+		case KEY_XMSS_CERT:
+			append_hostkey_type(b, sshkey_ssh_name(key));
+			break;
+		}
+	}
+	if ((ret = sshbuf_dup_string(b)) == NULL)
+		fatal("%s: sshbuf_dup_string failed", __func__);
+	sshbuf_free(b);
+	debug("%s: %s", __func__, ret);
+	return ret;
+}
+
+static struct sshkey *
+get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
+{
+	u_int i;
+	struct sshkey *key;
+
+	for (i = 0; i < options.num_host_key_files; i++) {
+		switch (type) {
+		case KEY_RSA_CERT:
+		case KEY_DSA_CERT:
+		case KEY_ECDSA_CERT:
+		case KEY_ED25519_CERT:
+		case KEY_XMSS_CERT:
+			key = sensitive_data.host_certificates[i];
+			break;
+		default:
+			key = sensitive_data.host_keys[i];
+			if (key == NULL && !need_private)
+				key = sensitive_data.host_pubkeys[i];
+			break;
+		}
+		if (key != NULL && key->type == type &&
+		    (key->type != KEY_ECDSA || key->ecdsa_nid == nid))
+			return need_private ?
+			    sensitive_data.host_keys[i] : key;
+	}
+	return NULL;
+}
+
+struct sshkey *
+get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
+{
+	return get_hostkey_by_type(type, nid, 0, ssh);
+}
+
+struct sshkey *
+get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
+{
+	return get_hostkey_by_type(type, nid, 1, ssh);
+}
+
+struct sshkey *
+get_hostkey_by_index(int ind)
+{
+	if (ind < 0 || (u_int)ind >= options.num_host_key_files)
+		return (NULL);
+	return (sensitive_data.host_keys[ind]);
+}
+
+struct sshkey *
+get_hostkey_public_by_index(int ind, struct ssh *ssh)
+{
+	if (ind < 0 || (u_int)ind >= options.num_host_key_files)
+		return (NULL);
+	return (sensitive_data.host_pubkeys[ind]);
+}
+
+int
+get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
+{
+	u_int i;
+
+	for (i = 0; i < options.num_host_key_files; i++) {
+		if (sshkey_is_cert(key)) {
+			if (key == sensitive_data.host_certificates[i] ||
+			    (compare && sensitive_data.host_certificates[i] &&
+			    sshkey_equal(key,
+			    sensitive_data.host_certificates[i])))
+				return (i);
+		} else {
+			if (key == sensitive_data.host_keys[i] ||
+			    (compare && sensitive_data.host_keys[i] &&
+			    sshkey_equal(key, sensitive_data.host_keys[i])))
+				return (i);
+			if (key == sensitive_data.host_pubkeys[i] ||
+			    (compare && sensitive_data.host_pubkeys[i] &&
+			    sshkey_equal(key, sensitive_data.host_pubkeys[i])))
+				return (i);
+		}
+	}
+	return (-1);
+}
+
+/* Inform the client of all hostkeys */
+static void
+notify_hostkeys(struct ssh *ssh)
+{
+	struct sshbuf *buf;
+	struct sshkey *key;
+	u_int i, nkeys;
+	int r;
+	char *fp;
+
+	/* Some clients cannot cope with the hostkeys message, skip those. */
+	if (datafellows & SSH_BUG_HOSTKEYS)
+		return;
+
+	if ((buf = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new", __func__);
+	for (i = nkeys = 0; i < options.num_host_key_files; i++) {
+		key = get_hostkey_public_by_index(i, ssh);
+		if (key == NULL || key->type == KEY_UNSPEC ||
+		    sshkey_is_cert(key))
+			continue;
+		fp = sshkey_fingerprint(key, options.fingerprint_hash,
+		    SSH_FP_DEFAULT);
+		debug3("%s: key %d: %s %s", __func__, i,
+		    sshkey_ssh_name(key), fp);
+		free(fp);
+		if (nkeys == 0) {
+			packet_start(SSH2_MSG_GLOBAL_REQUEST);
+			packet_put_cstring("hostkeys-00@openssh.com");
+			packet_put_char(0); /* want-reply */
+		}
+		sshbuf_reset(buf);
+		if ((r = sshkey_putb(key, buf)) != 0)
+			fatal("%s: couldn't put hostkey %d: %s",
+			    __func__, i, ssh_err(r));
+		packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
+		nkeys++;
+	}
+	debug3("%s: sent %u hostkeys", __func__, nkeys);
+	if (nkeys == 0)
+		fatal("%s: no hostkeys", __func__);
+	packet_send();
+	sshbuf_free(buf);
+}
+
+/*
+ * returns 1 if connection should be dropped, 0 otherwise.
+ * dropping starts at connection #max_startups_begin with a probability
+ * of (max_startups_rate/100). the probability increases linearly until
+ * all connections are dropped for startups > max_startups
+ */
+static int
+drop_connection(int startups)
+{
+	int p, r;
+
+	if (startups < options.max_startups_begin)
+		return 0;
+	if (startups >= options.max_startups)
+		return 1;
+	if (options.max_startups_rate == 100)
+		return 1;
+
+	p  = 100 - options.max_startups_rate;
+	p *= startups - options.max_startups_begin;
+	p /= options.max_startups - options.max_startups_begin;
+	p += options.max_startups_rate;
+	r = arc4random_uniform(100);
+
+	debug("drop_connection: p %d, r %d", p, r);
+	return (r < p) ? 1 : 0;
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr, "%s, %s\n",
+	    SSH_RELEASE,
+#ifdef WITH_OPENSSL
+	    SSLeay_version(SSLEAY_VERSION)
+#else
+	    "without OpenSSL"
+#endif
+	);
+	fprintf(stderr,
+"usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
+"            [-E log_file] [-f config_file] [-g login_grace_time]\n"
+"            [-h host_key_file] [-o option] [-p port] [-u len]\n"
+	);
+	exit(1);
+}
+
+static void
+send_rexec_state(int fd, struct sshbuf *conf)
+{
+	struct sshbuf *m;
+	int r;
+
+	debug3("%s: entering fd = %d config len %zu", __func__, fd,
+	    sshbuf_len(conf));
+
+	/*
+	 * Protocol from reexec master to child:
+	 *	string	configuration
+	 *	string rngseed		(only if OpenSSL is not self-seeded)
+	 */
+	if ((m = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	if ((r = sshbuf_put_stringb(m, conf)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
+	rexec_send_rng_seed(m);
+#endif
+
+	if (ssh_msg_send(fd, 0, m) == -1)
+		fatal("%s: ssh_msg_send failed", __func__);
+
+	sshbuf_free(m);
+
+	debug3("%s: done", __func__);
+}
+
+static void
+recv_rexec_state(int fd, struct sshbuf *conf)
+{
+	struct sshbuf *m;
+	u_char *cp, ver;
+	size_t len;
+	int r;
+
+	debug3("%s: entering fd = %d", __func__, fd);
+
+	if ((m = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	if (ssh_msg_recv(fd, m) == -1)
+		fatal("%s: ssh_msg_recv failed", __func__);
+	if ((r = sshbuf_get_u8(m, &ver)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (ver != 0)
+		fatal("%s: rexec version mismatch", __func__);
+	if ((r = sshbuf_get_string(m, &cp, &len)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
+	rexec_recv_rng_seed(m);
+#endif
+
+	free(cp);
+	sshbuf_free(m);
+
+	debug3("%s: done", __func__);
+}
+
+/* Accept a connection from inetd */
+static void
+server_accept_inetd(int *sock_in, int *sock_out)
+{
+	int fd;
+
+	startup_pipe = -1;
+	if (rexeced_flag) {
+		close(REEXEC_CONFIG_PASS_FD);
+		*sock_in = *sock_out = dup(STDIN_FILENO);
+		if (!debug_flag) {
+			startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
+			close(REEXEC_STARTUP_PIPE_FD);
+		}
+	} else {
+		*sock_in = dup(STDIN_FILENO);
+		*sock_out = dup(STDOUT_FILENO);
+	}
+	/*
+	 * We intentionally do not close the descriptors 0, 1, and 2
+	 * as our code for setting the descriptors won't work if
+	 * ttyfd happens to be one of those.
+	 */
+	if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
+		dup2(fd, STDIN_FILENO);
+		dup2(fd, STDOUT_FILENO);
+		if (!log_stderr)
+			dup2(fd, STDERR_FILENO);
+		if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
+			close(fd);
+	}
+	debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
+}
+
+/*
+ * Listen for TCP connections
+ */
+static void
+listen_on_addrs(struct listenaddr *la)
+{
+	int ret, listen_sock;
+	struct addrinfo *ai;
+	char ntop[NI_MAXHOST], strport[NI_MAXSERV];
+
+	for (ai = la->addrs; ai; ai = ai->ai_next) {
+		if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+			continue;
+		if (num_listen_socks >= MAX_LISTEN_SOCKS)
+			fatal("Too many listen sockets. "
+			    "Enlarge MAX_LISTEN_SOCKS");
+		if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
+		    ntop, sizeof(ntop), strport, sizeof(strport),
+		    NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
+			error("getnameinfo failed: %.100s",
+			    ssh_gai_strerror(ret));
+			continue;
+		}
+		/* Create socket for listening. */
+		listen_sock = socket(ai->ai_family, ai->ai_socktype,
+		    ai->ai_protocol);
+		if (listen_sock < 0) {
+			/* kernel may not support ipv6 */
+			verbose("socket: %.100s", strerror(errno));
+			continue;
+		}
+		if (set_nonblock(listen_sock) == -1) {
+			close(listen_sock);
+			continue;
+		}
+		if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
+			verbose("socket: CLOEXEC: %s", strerror(errno));
+			close(listen_sock);
+			continue;
+		}
+		/* Socket options */
+		set_reuseaddr(listen_sock);
+		if (la->rdomain != NULL &&
+		    set_rdomain(listen_sock, la->rdomain) == -1) {
+			close(listen_sock);
+			continue;
+		}
+
+		/* Only communicate in IPv6 over AF_INET6 sockets. */
+		if (ai->ai_family == AF_INET6)
+			sock_set_v6only(listen_sock);
+
+		debug("Bind to port %s on %s.", strport, ntop);
+
+		/* Bind the socket to the desired port. */
+		if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
+			error("Bind to port %s on %s failed: %.200s.",
+			    strport, ntop, strerror(errno));
+			close(listen_sock);
+			continue;
+		}
+		listen_socks[num_listen_socks] = listen_sock;
+		num_listen_socks++;
+
+		/* Start listening on the port. */
+		if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
+			fatal("listen on [%s]:%s: %.100s",
+			    ntop, strport, strerror(errno));
+		logit("Server listening on %s port %s%s%s.",
+		    ntop, strport,
+		    la->rdomain == NULL ? "" : " rdomain ",
+		    la->rdomain == NULL ? "" : la->rdomain);
+	}
+}
+
+static void
+server_listen(void)
+{
+	u_int i;
+
+	for (i = 0; i < options.num_listen_addrs; i++) {
+		listen_on_addrs(&options.listen_addrs[i]);
+		freeaddrinfo(options.listen_addrs[i].addrs);
+		free(options.listen_addrs[i].rdomain);
+		memset(&options.listen_addrs[i], 0,
+		    sizeof(options.listen_addrs[i]));
+	}
+	free(options.listen_addrs);
+	options.listen_addrs = NULL;
+	options.num_listen_addrs = 0;
+
+	if (!num_listen_socks)
+		fatal("Cannot bind any address.");
+}
+
+/*
+ * The main TCP accept loop. Note that, for the non-debug case, returns
+ * from this function are in a forked subprocess.
+ */
+static void
+server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
+{
+	fd_set *fdset;
+	int i, j, ret, maxfd;
+	int startups = 0;
+	int startup_p[2] = { -1 , -1 };
+	struct sockaddr_storage from;
+	socklen_t fromlen;
+	pid_t pid;
+	u_char rnd[256];
+
+	/* setup fd set for accept */
+	fdset = NULL;
+	maxfd = 0;
+	for (i = 0; i < num_listen_socks; i++)
+		if (listen_socks[i] > maxfd)
+			maxfd = listen_socks[i];
+	/* pipes connected to unauthenticated childs */
+	startup_pipes = xcalloc(options.max_startups, sizeof(int));
+	for (i = 0; i < options.max_startups; i++)
+		startup_pipes[i] = -1;
+
+	/*
+	 * Stay listening for connections until the system crashes or
+	 * the daemon is killed with a signal.
+	 */
+	for (;;) {
+		if (received_sighup)
+			sighup_restart();
+		free(fdset);
+		fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
+		    sizeof(fd_mask));
+
+		for (i = 0; i < num_listen_socks; i++)
+			FD_SET(listen_socks[i], fdset);
+		for (i = 0; i < options.max_startups; i++)
+			if (startup_pipes[i] != -1)
+				FD_SET(startup_pipes[i], fdset);
+
+		/* Wait in select until there is a connection. */
+		ret = select(maxfd+1, fdset, NULL, NULL, NULL);
+		if (ret < 0 && errno != EINTR)
+			error("select: %.100s", strerror(errno));
+		if (received_sigterm) {
+			logit("Received signal %d; terminating.",
+			    (int) received_sigterm);
+			close_listen_socks();
+			if (options.pid_file != NULL)
+				unlink(options.pid_file);
+			exit(received_sigterm == SIGTERM ? 0 : 255);
+		}
+		if (ret < 0)
+			continue;
+
+		for (i = 0; i < options.max_startups; i++)
+			if (startup_pipes[i] != -1 &&
+			    FD_ISSET(startup_pipes[i], fdset)) {
+				/*
+				 * the read end of the pipe is ready
+				 * if the child has closed the pipe
+				 * after successful authentication
+				 * or if the child has died
+				 */
+				close(startup_pipes[i]);
+				startup_pipes[i] = -1;
+				startups--;
+			}
+		for (i = 0; i < num_listen_socks; i++) {
+			if (!FD_ISSET(listen_socks[i], fdset))
+				continue;
+			fromlen = sizeof(from);
+			*newsock = accept(listen_socks[i],
+			    (struct sockaddr *)&from, &fromlen);
+			if (*newsock < 0) {
+				if (errno != EINTR && errno != EWOULDBLOCK &&
+				    errno != ECONNABORTED && errno != EAGAIN)
+					error("accept: %.100s",
+					    strerror(errno));
+				if (errno == EMFILE || errno == ENFILE)
+					usleep(100 * 1000);
+				continue;
+			}
+			if (unset_nonblock(*newsock) == -1) {
+				close(*newsock);
+				continue;
+			}
+			if (drop_connection(startups) == 1) {
+				char *laddr = get_local_ipaddr(*newsock);
+				char *raddr = get_peer_ipaddr(*newsock);
+
+				verbose("drop connection #%d from [%s]:%d "
+				    "on [%s]:%d past MaxStartups", startups,
+				    raddr, get_peer_port(*newsock),
+				    laddr, get_local_port(*newsock));
+				free(laddr);
+				free(raddr);
+				close(*newsock);
+				continue;
+			}
+			if (pipe(startup_p) == -1) {
+				close(*newsock);
+				continue;
+			}
+
+			if (rexec_flag && socketpair(AF_UNIX,
+			    SOCK_STREAM, 0, config_s) == -1) {
+				error("reexec socketpair: %s",
+				    strerror(errno));
+				close(*newsock);
+				close(startup_p[0]);
+				close(startup_p[1]);
+				continue;
+			}
+
+			for (j = 0; j < options.max_startups; j++)
+				if (startup_pipes[j] == -1) {
+					startup_pipes[j] = startup_p[0];
+					if (maxfd < startup_p[0])
+						maxfd = startup_p[0];
+					startups++;
+					break;
+				}
+
+			/*
+			 * Got connection.  Fork a child to handle it, unless
+			 * we are in debugging mode.
+			 */
+			if (debug_flag) {
+				/*
+				 * In debugging mode.  Close the listening
+				 * socket, and start processing the
+				 * connection without forking.
+				 */
+				debug("Server will not fork when running in debugging mode.");
+				close_listen_socks();
+				*sock_in = *newsock;
+				*sock_out = *newsock;
+				close(startup_p[0]);
+				close(startup_p[1]);
+				startup_pipe = -1;
+				pid = getpid();
+				if (rexec_flag) {
+					send_rexec_state(config_s[0], cfg);
+					close(config_s[0]);
+				}
+				break;
+			}
+
+			/*
+			 * Normal production daemon.  Fork, and have
+			 * the child process the connection. The
+			 * parent continues listening.
+			 */
+			platform_pre_fork();
+			if ((pid = fork()) == 0) {
+				/*
+				 * Child.  Close the listening and
+				 * max_startup sockets.  Start using
+				 * the accepted socket. Reinitialize
+				 * logging (since our pid has changed).
+				 * We break out of the loop to handle
+				 * the connection.
+				 */
+				platform_post_fork_child();
+				startup_pipe = startup_p[1];
+				close_startup_pipes();
+				close_listen_socks();
+				*sock_in = *newsock;
+				*sock_out = *newsock;
+				log_init(__progname,
+				    options.log_level,
+				    options.log_facility,
+				    log_stderr);
+				if (rexec_flag)
+					close(config_s[0]);
+				break;
+			}
+
+			/* Parent.  Stay in the loop. */
+			platform_post_fork_parent(pid);
+			if (pid < 0)
+				error("fork: %.100s", strerror(errno));
+			else
+				debug("Forked child %ld.", (long)pid);
+
+			close(startup_p[1]);
+
+			if (rexec_flag) {
+				send_rexec_state(config_s[0], cfg);
+				close(config_s[0]);
+				close(config_s[1]);
+			}
+			close(*newsock);
+
+			/*
+			 * Ensure that our random state differs
+			 * from that of the child
+			 */
+			arc4random_stir();
+			arc4random_buf(rnd, sizeof(rnd));
+#ifdef WITH_OPENSSL
+			RAND_seed(rnd, sizeof(rnd));
+			if ((RAND_bytes((u_char *)rnd, 1)) != 1)
+				fatal("%s: RAND_bytes failed", __func__);
+#endif
+			explicit_bzero(rnd, sizeof(rnd));
+		}
+
+		/* child process check (or debug mode) */
+		if (num_listen_socks < 0)
+			break;
+	}
+}
+
+/*
+ * If IP options are supported, make sure there are none (log and
+ * return an error if any are found).  Basically we are worried about
+ * source routing; it can be used to pretend you are somebody
+ * (ip-address) you are not. That itself may be "almost acceptable"
+ * under certain circumstances, but rhosts authentication is useless
+ * if source routing is accepted. Notice also that if we just dropped
+ * source routing here, the other side could use IP spoofing to do
+ * rest of the interaction and could still bypass security.  So we
+ * exit here if we detect any IP options.
+ */
+static void
+check_ip_options(struct ssh *ssh)
+{
+#ifdef IP_OPTIONS
+	int sock_in = ssh_packet_get_connection_in(ssh);
+	struct sockaddr_storage from;
+	u_char opts[200];
+	socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
+	char text[sizeof(opts) * 3 + 1];
+
+	memset(&from, 0, sizeof(from));
+	if (getpeername(sock_in, (struct sockaddr *)&from,
+	    &fromlen) < 0)
+		return;
+	if (from.ss_family != AF_INET)
+		return;
+	/* XXX IPv6 options? */
+
+	if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
+	    &option_size) >= 0 && option_size != 0) {
+		text[0] = '\0';
+		for (i = 0; i < option_size; i++)
+			snprintf(text + i*3, sizeof(text) - i*3,
+			    " %2.2x", opts[i]);
+		fatal("Connection from %.100s port %d with IP opts: %.800s",
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
+	}
+	return;
+#endif /* IP_OPTIONS */
+}
+
+/* Set the routing domain for this process */
+static void
+set_process_rdomain(struct ssh *ssh, const char *name)
+{
+#if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
+	if (name == NULL)
+		return; /* default */
+
+	if (strcmp(name, "%D") == 0) {
+		/* "expands" to routing domain of connection */
+		if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
+			return;
+	}
+	/* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
+	return sys_set_process_rdomain(name);
+#elif defined(__OpenBSD__)
+	int rtable, ortable = getrtable();
+	const char *errstr;
+
+	if (name == NULL)
+		return; /* default */
+
+	if (strcmp(name, "%D") == 0) {
+		/* "expands" to routing domain of connection */
+		if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
+			return;
+	}
+
+	rtable = (int)strtonum(name, 0, 255, &errstr);
+	if (errstr != NULL) /* Shouldn't happen */
+		fatal("Invalid routing domain \"%s\": %s", name, errstr);
+	if (rtable != ortable && setrtable(rtable) != 0)
+		fatal("Unable to set routing domain %d: %s",
+		    rtable, strerror(errno));
+	debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable);
+#else /* defined(__OpenBSD__) */
+	fatal("Unable to set routing domain: not supported in this platform");
+#endif
+}
+
+static void
+accumulate_host_timing_secret(struct sshbuf *server_cfg,
+    const struct sshkey *key)
+{
+	static struct ssh_digest_ctx *ctx;
+	u_char *hash;
+	size_t len;
+	struct sshbuf *buf;
+	int r;
+
+	if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
+		fatal("%s: ssh_digest_start", __func__);
+	if (key == NULL) { /* finalize */
+		/* add server config in case we are using agent for host keys */
+		if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
+		    sshbuf_len(server_cfg)) != 0)
+			fatal("%s: ssh_digest_update", __func__);
+		len = ssh_digest_bytes(SSH_DIGEST_SHA512);
+		hash = xmalloc(len);
+		if (ssh_digest_final(ctx, hash, len) != 0)
+			fatal("%s: ssh_digest_final", __func__);
+		options.timing_secret = PEEK_U64(hash);
+		freezero(hash, len);
+		ssh_digest_free(ctx);
+		ctx = NULL;
+		return;
+	}
+	if ((buf = sshbuf_new()) == NULL)
+		fatal("%s could not allocate buffer", __func__);
+	if ((r = sshkey_private_serialize(key, buf)) != 0)
+		fatal("sshkey_private_serialize: %s", ssh_err(r));
+	if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
+		fatal("%s: ssh_digest_update", __func__);
+	sshbuf_reset(buf);
+	sshbuf_free(buf);
+}
+
+/*
+ * Main program for the daemon.
+ */
+int
+main(int ac, char **av)
+{
+	struct ssh *ssh = NULL;
+	extern char *optarg;
+	extern int optind;
+	int r, opt, on = 1, already_daemon, remote_port;
+	int sock_in = -1, sock_out = -1, newsock = -1;
+	const char *remote_ip, *rdomain;
+	char *fp, *line, *laddr, *logfile = NULL;
+	int config_s[2] = { -1 , -1 };
+	u_int i, j;
+	u_int64_t ibytes, obytes;
+	mode_t new_umask;
+	struct sshkey *key;
+	struct sshkey *pubkey;
+	int keytype;
+	Authctxt *authctxt;
+	struct connection_info *connection_info = NULL;
+
+	ssh_malloc_init();	/* must be called before any mallocs */
+
+#ifdef HAVE_SECUREWARE
+	(void)set_auth_parameters(ac, av);
+#endif
+	__progname = ssh_get_progname(av[0]);
+
+	/* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
+	saved_argc = ac;
+	rexec_argc = ac;
+	saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
+	for (i = 0; (int)i < ac; i++)
+		saved_argv[i] = xstrdup(av[i]);
+	saved_argv[i] = NULL;
+
+#ifndef HAVE_SETPROCTITLE
+	/* Prepare for later setproctitle emulation */
+	compat_init_setproctitle(ac, av);
+	av = saved_argv;
+#endif
+
+	if (geteuid() == 0 && setgroups(0, NULL) == -1)
+		debug("setgroups(): %.200s", strerror(errno));
+
+	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
+	sanitise_stdfd();
+
+	/* Initialize configuration options to their default values. */
+	initialize_server_options(&options);
+
+	/* Parse command-line arguments. */
+	while ((opt = getopt(ac, av,
+	    "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
+		switch (opt) {
+		case '4':
+			options.address_family = AF_INET;
+			break;
+		case '6':
+			options.address_family = AF_INET6;
+			break;
+		case 'f':
+			config_file_name = optarg;
+			break;
+		case 'c':
+			servconf_add_hostcert("[command-line]", 0,
+			    &options, optarg);
+			break;
+		case 'd':
+			if (debug_flag == 0) {
+				debug_flag = 1;
+				options.log_level = SYSLOG_LEVEL_DEBUG1;
+			} else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
+				options.log_level++;
+			break;
+		case 'D':
+			no_daemon_flag = 1;
+			break;
+		case 'E':
+			logfile = optarg;
+			/* FALLTHROUGH */
+		case 'e':
+			log_stderr = 1;
+			break;
+		case 'i':
+			inetd_flag = 1;
+			break;
+		case 'r':
+			rexec_flag = 0;
+			break;
+		case 'R':
+			rexeced_flag = 1;
+			inetd_flag = 1;
+			break;
+		case 'Q':
+			/* ignored */
+			break;
+		case 'q':
+			options.log_level = SYSLOG_LEVEL_QUIET;
+			break;
+		case 'b':
+			/* protocol 1, ignored */
+			break;
+		case 'p':
+			options.ports_from_cmdline = 1;
+			if (options.num_ports >= MAX_PORTS) {
+				fprintf(stderr, "too many ports.\n");
+				exit(1);
+			}
+			options.ports[options.num_ports++] = a2port(optarg);
+			if (options.ports[options.num_ports-1] <= 0) {
+				fprintf(stderr, "Bad port number.\n");
+				exit(1);
+			}
+			break;
+		case 'g':
+			if ((options.login_grace_time = convtime(optarg)) == -1) {
+				fprintf(stderr, "Invalid login grace time.\n");
+				exit(1);
+			}
+			break;
+		case 'k':
+			/* protocol 1, ignored */
+			break;
+		case 'h':
+			servconf_add_hostkey("[command-line]", 0,
+			    &options, optarg);
+			break;
+		case 't':
+			test_flag = 1;
+			break;
+		case 'T':
+			test_flag = 2;
+			break;
+		case 'C':
+			connection_info = get_connection_info(0, 0);
+			if (parse_server_match_testspec(connection_info,
+			    optarg) == -1)
+				exit(1);
+			break;
+		case 'u':
+			utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
+			if (utmp_len > HOST_NAME_MAX+1) {
+				fprintf(stderr, "Invalid utmp length.\n");
+				exit(1);
+			}
+			break;
+		case 'o':
+			line = xstrdup(optarg);
+			if (process_server_config_line(&options, line,
+			    "command-line", 0, NULL, NULL) != 0)
+				exit(1);
+			free(line);
+			break;
+		case '?':
+		default:
+			usage();
+			break;
+		}
+	}
+	if (rexeced_flag || inetd_flag)
+		rexec_flag = 0;
+	if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
+		fatal("sshd re-exec requires execution with an absolute path");
+	if (rexeced_flag)
+		closefrom(REEXEC_MIN_FREE_FD);
+	else
+		closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
+
+#ifdef WITH_OPENSSL
+	OpenSSL_add_all_algorithms();
+#endif
+
+	/* If requested, redirect the logs to the specified logfile. */
+	if (logfile != NULL)
+		log_redirect_stderr_to(logfile);
+	/*
+	 * Force logging to stderr until we have loaded the private host
+	 * key (unless started from inetd)
+	 */
+	log_init(__progname,
+	    options.log_level == SYSLOG_LEVEL_NOT_SET ?
+	    SYSLOG_LEVEL_INFO : options.log_level,
+	    options.log_facility == SYSLOG_FACILITY_NOT_SET ?
+	    SYSLOG_FACILITY_AUTH : options.log_facility,
+	    log_stderr || !inetd_flag);
+
+	/*
+	 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
+	 * root's environment
+	 */
+	if (getenv("KRB5CCNAME") != NULL)
+		(void) unsetenv("KRB5CCNAME");
+
+	sensitive_data.have_ssh2_key = 0;
+
+	/*
+	 * If we're not doing an extended test do not silently ignore connection
+	 * test params.
+	 */
+	if (test_flag < 2 && connection_info != NULL)
+		fatal("Config test connection parameter (-C) provided without "
+		   "test mode (-T)");
+
+	/* Fetch our configuration */
+	if ((cfg = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	if (rexeced_flag)
+		recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg);
+	else if (strcasecmp(config_file_name, "none") != 0)
+		load_server_config(config_file_name, cfg);
+
+	parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
+	    cfg, NULL);
+
+	seed_rng();
+
+	/* Fill in default values for those options not explicitly set. */
+	fill_default_server_options(&options);
+
+	/* challenge-response is implemented via keyboard interactive */
+	if (options.challenge_response_authentication)
+		options.kbd_interactive_authentication = 1;
+
+	/* Check that options are sensible */
+	if (options.authorized_keys_command_user == NULL &&
+	    (options.authorized_keys_command != NULL &&
+	    strcasecmp(options.authorized_keys_command, "none") != 0))
+		fatal("AuthorizedKeysCommand set without "
+		    "AuthorizedKeysCommandUser");
+	if (options.authorized_principals_command_user == NULL &&
+	    (options.authorized_principals_command != NULL &&
+	    strcasecmp(options.authorized_principals_command, "none") != 0))
+		fatal("AuthorizedPrincipalsCommand set without "
+		    "AuthorizedPrincipalsCommandUser");
+
+	/*
+	 * Check whether there is any path through configured auth methods.
+	 * Unfortunately it is not possible to verify this generally before
+	 * daemonisation in the presence of Match block, but this catches
+	 * and warns for trivial misconfigurations that could break login.
+	 */
+	if (options.num_auth_methods != 0) {
+		for (i = 0; i < options.num_auth_methods; i++) {
+			if (auth2_methods_valid(options.auth_methods[i],
+			    1) == 0)
+				break;
+		}
+		if (i >= options.num_auth_methods)
+			fatal("AuthenticationMethods cannot be satisfied by "
+			    "enabled authentication methods");
+	}
+
+	/* Check that there are no remaining arguments. */
+	if (optind < ac) {
+		fprintf(stderr, "Extra argument %s.\n", av[optind]);
+		exit(1);
+	}
+
+	debug("sshd version %s, %s", SSH_VERSION,
+#ifdef WITH_OPENSSL
+	    SSLeay_version(SSLEAY_VERSION)
+#else
+	    "without OpenSSL"
+#endif
+	);
+
+	/* Store privilege separation user for later use if required. */
+	privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
+	if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
+		if (privsep_chroot || options.kerberos_authentication)
+			fatal("Privilege separation user %s does not exist",
+			    SSH_PRIVSEP_USER);
+	} else {
+		privsep_pw = pwcopy(privsep_pw);
+		freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
+		privsep_pw->pw_passwd = xstrdup("*");
+	}
+	endpwent();
+
+	/* load host keys */
+	sensitive_data.host_keys = xcalloc(options.num_host_key_files,
+	    sizeof(struct sshkey *));
+	sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
+	    sizeof(struct sshkey *));
+
+	if (options.host_key_agent) {
+		if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
+			setenv(SSH_AUTHSOCKET_ENV_NAME,
+			    options.host_key_agent, 1);
+		if ((r = ssh_get_authentication_socket(NULL)) == 0)
+			have_agent = 1;
+		else
+			error("Could not connect to agent \"%s\": %s",
+			    options.host_key_agent, ssh_err(r));
+	}
+
+	for (i = 0; i < options.num_host_key_files; i++) {
+		if (options.host_key_files[i] == NULL)
+			continue;
+		if ((r = sshkey_load_private(options.host_key_files[i], "",
+		    &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
+			error("Error loading host key \"%s\": %s",
+			    options.host_key_files[i], ssh_err(r));
+		if ((r = sshkey_load_public(options.host_key_files[i],
+		    &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
+			error("Error loading host key \"%s\": %s",
+			    options.host_key_files[i], ssh_err(r));
+		if (pubkey == NULL && key != NULL)
+			if ((r = sshkey_from_private(key, &pubkey)) != 0)
+				fatal("Could not demote key: \"%s\": %s",
+				    options.host_key_files[i], ssh_err(r));
+		sensitive_data.host_keys[i] = key;
+		sensitive_data.host_pubkeys[i] = pubkey;
+
+		if (key == NULL && pubkey != NULL && have_agent) {
+			debug("will rely on agent for hostkey %s",
+			    options.host_key_files[i]);
+			keytype = pubkey->type;
+		} else if (key != NULL) {
+			keytype = key->type;
+			accumulate_host_timing_secret(cfg, key);
+		} else {
+			error("Could not load host key: %s",
+			    options.host_key_files[i]);
+			sensitive_data.host_keys[i] = NULL;
+			sensitive_data.host_pubkeys[i] = NULL;
+			continue;
+		}
+
+		switch (keytype) {
+		case KEY_RSA:
+		case KEY_DSA:
+		case KEY_ECDSA:
+		case KEY_ED25519:
+		case KEY_XMSS:
+			if (have_agent || key != NULL)
+				sensitive_data.have_ssh2_key = 1;
+			break;
+		}
+		if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
+		    SSH_FP_DEFAULT)) == NULL)
+			fatal("sshkey_fingerprint failed");
+		debug("%s host key #%d: %s %s",
+		    key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
+		free(fp);
+	}
+	accumulate_host_timing_secret(cfg, NULL);
+	if (!sensitive_data.have_ssh2_key) {
+		logit("sshd: no hostkeys available -- exiting.");
+		exit(1);
+	}
+
+	/*
+	 * Load certificates. They are stored in an array at identical
+	 * indices to the public keys that they relate to.
+	 */
+	sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
+	    sizeof(struct sshkey *));
+	for (i = 0; i < options.num_host_key_files; i++)
+		sensitive_data.host_certificates[i] = NULL;
+
+	for (i = 0; i < options.num_host_cert_files; i++) {
+		if (options.host_cert_files[i] == NULL)
+			continue;
+		if ((r = sshkey_load_public(options.host_cert_files[i],
+		    &key, NULL)) != 0) {
+			error("Could not load host certificate \"%s\": %s",
+			    options.host_cert_files[i], ssh_err(r));
+			continue;
+		}
+		if (!sshkey_is_cert(key)) {
+			error("Certificate file is not a certificate: %s",
+			    options.host_cert_files[i]);
+			sshkey_free(key);
+			continue;
+		}
+		/* Find matching private key */
+		for (j = 0; j < options.num_host_key_files; j++) {
+			if (sshkey_equal_public(key,
+			    sensitive_data.host_keys[j])) {
+				sensitive_data.host_certificates[j] = key;
+				break;
+			}
+		}
+		if (j >= options.num_host_key_files) {
+			error("No matching private key for certificate: %s",
+			    options.host_cert_files[i]);
+			sshkey_free(key);
+			continue;
+		}
+		sensitive_data.host_certificates[j] = key;
+		debug("host certificate: #%u type %d %s", j, key->type,
+		    sshkey_type(key));
+	}
+
+	if (privsep_chroot) {
+		struct stat st;
+
+		if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
+		    (S_ISDIR(st.st_mode) == 0))
+			fatal("Missing privilege separation directory: %s",
+			    _PATH_PRIVSEP_CHROOT_DIR);
+
+#ifdef HAVE_CYGWIN
+		if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
+		    (st.st_uid != getuid () ||
+		    (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
+#else
+		if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
+#endif
+			fatal("%s must be owned by root and not group or "
+			    "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
+	}
+
+	if (test_flag > 1) {
+		/*
+		 * If no connection info was provided by -C then use
+		 * use a blank one that will cause no predicate to match.
+		 */
+		if (connection_info == NULL)
+			connection_info = get_connection_info(0, 0);
+		parse_server_match_config(&options, connection_info);
+		dump_config(&options);
+	}
+
+	/* Configuration looks good, so exit if in test mode. */
+	if (test_flag)
+		exit(0);
+
+	/*
+	 * Clear out any supplemental groups we may have inherited.  This
+	 * prevents inadvertent creation of files with bad modes (in the
+	 * portable version at least, it's certainly possible for PAM
+	 * to create a file, and we can't control the code in every
+	 * module which might be used).
+	 */
+	if (setgroups(0, NULL) < 0)
+		debug("setgroups() failed: %.200s", strerror(errno));
+
+	if (rexec_flag) {
+		if (rexec_argc < 0)
+			fatal("rexec_argc %d < 0", rexec_argc);
+		rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
+		for (i = 0; i < (u_int)rexec_argc; i++) {
+			debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
+			rexec_argv[i] = saved_argv[i];
+		}
+		rexec_argv[rexec_argc] = "-R";
+		rexec_argv[rexec_argc + 1] = NULL;
+	}
+
+	/* Ensure that umask disallows at least group and world write */
+	new_umask = umask(0077) | 0022;
+	(void) umask(new_umask);
+
+	/* Initialize the log (it is reinitialized below in case we forked). */
+	if (debug_flag && (!inetd_flag || rexeced_flag))
+		log_stderr = 1;
+	log_init(__progname, options.log_level, options.log_facility, log_stderr);
+
+	/*
+	 * If not in debugging mode, not started from inetd and not already
+	 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
+	 * terminal, and fork.  The original process exits.
+	 */
+	already_daemon = daemonized();
+	if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
+
+		if (daemon(0, 0) < 0)
+			fatal("daemon() failed: %.200s", strerror(errno));
+
+		disconnect_controlling_tty();
+	}
+	/* Reinitialize the log (because of the fork above). */
+	log_init(__progname, options.log_level, options.log_facility, log_stderr);
+
+	/* Chdir to the root directory so that the current disk can be
+	   unmounted if desired. */
+	if (chdir("/") == -1)
+		error("chdir(\"/\"): %s", strerror(errno));
+
+	/* ignore SIGPIPE */
+	signal(SIGPIPE, SIG_IGN);
+
+	/* Get a connection, either from inetd or a listening TCP socket */
+	if (inetd_flag) {
+		server_accept_inetd(&sock_in, &sock_out);
+	} else {
+		platform_pre_listen();
+		server_listen();
+
+		signal(SIGHUP, sighup_handler);
+		signal(SIGCHLD, main_sigchld_handler);
+		signal(SIGTERM, sigterm_handler);
+		signal(SIGQUIT, sigterm_handler);
+
+		/*
+		 * Write out the pid file after the sigterm handler
+		 * is setup and the listen sockets are bound
+		 */
+		if (options.pid_file != NULL && !debug_flag) {
+			FILE *f = fopen(options.pid_file, "w");
+
+			if (f == NULL) {
+				error("Couldn't create pid file \"%s\": %s",
+				    options.pid_file, strerror(errno));
+			} else {
+				fprintf(f, "%ld\n", (long) getpid());
+				fclose(f);
+			}
+		}
+
+		/* Accept a connection and return in a forked child */
+		server_accept_loop(&sock_in, &sock_out,
+		    &newsock, config_s);
+	}
+
+	/* This is the child processing a new connection. */
+	setproctitle("%s", "[accepted]");
+
+	/*
+	 * Create a new session and process group since the 4.4BSD
+	 * setlogin() affects the entire process group.  We don't
+	 * want the child to be able to affect the parent.
+	 */
+#if !defined(SSHD_ACQUIRES_CTTY)
+	/*
+	 * If setsid is called, on some platforms sshd will later acquire a
+	 * controlling terminal which will result in "could not set
+	 * controlling tty" errors.
+	 */
+	if (!debug_flag && !inetd_flag && setsid() < 0)
+		error("setsid: %.100s", strerror(errno));
+#endif
+
+	if (rexec_flag) {
+		int fd;
+
+		debug("rexec start in %d out %d newsock %d pipe %d sock %d",
+		    sock_in, sock_out, newsock, startup_pipe, config_s[0]);
+		dup2(newsock, STDIN_FILENO);
+		dup2(STDIN_FILENO, STDOUT_FILENO);
+		if (startup_pipe == -1)
+			close(REEXEC_STARTUP_PIPE_FD);
+		else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
+			dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
+			close(startup_pipe);
+			startup_pipe = REEXEC_STARTUP_PIPE_FD;
+		}
+
+		dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
+		close(config_s[1]);
+
+		execv(rexec_argv[0], rexec_argv);
+
+		/* Reexec has failed, fall back and continue */
+		error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
+		recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
+		log_init(__progname, options.log_level,
+		    options.log_facility, log_stderr);
+
+		/* Clean up fds */
+		close(REEXEC_CONFIG_PASS_FD);
+		newsock = sock_out = sock_in = dup(STDIN_FILENO);
+		if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
+			dup2(fd, STDIN_FILENO);
+			dup2(fd, STDOUT_FILENO);
+			if (fd > STDERR_FILENO)
+				close(fd);
+		}
+		debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
+		    sock_in, sock_out, newsock, startup_pipe, config_s[0]);
+	}
+
+	/* Executed child processes don't need these. */
+	fcntl(sock_out, F_SETFD, FD_CLOEXEC);
+	fcntl(sock_in, F_SETFD, FD_CLOEXEC);
+
+	/*
+	 * Disable the key regeneration alarm.  We will not regenerate the
+	 * key since we are no longer in a position to give it to anyone. We
+	 * will not restart on SIGHUP since it no longer makes sense.
+	 */
+	alarm(0);
+	signal(SIGALRM, SIG_DFL);
+	signal(SIGHUP, SIG_DFL);
+	signal(SIGTERM, SIG_DFL);
+	signal(SIGQUIT, SIG_DFL);
+	signal(SIGCHLD, SIG_DFL);
+	signal(SIGINT, SIG_DFL);
+
+	/*
+	 * Register our connection.  This turns encryption off because we do
+	 * not have a key.
+	 */
+	packet_set_connection(sock_in, sock_out);
+	packet_set_server();
+	ssh = active_state; /* XXX */
+
+	check_ip_options(ssh);
+
+	/* Prepare the channels layer */
+	channel_init_channels(ssh);
+	channel_set_af(ssh, options.address_family);
+	process_permitopen(ssh, &options);
+
+	/* Set SO_KEEPALIVE if requested. */
+	if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
+	    setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
+		error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
+
+	if ((remote_port = ssh_remote_port(ssh)) < 0) {
+		debug("ssh_remote_port failed");
+		cleanup_exit(255);
+	}
+
+	if (options.routing_domain != NULL)
+		set_process_rdomain(ssh, options.routing_domain);
+
+	/*
+	 * The rest of the code depends on the fact that
+	 * ssh_remote_ipaddr() caches the remote ip, even if
+	 * the socket goes away.
+	 */
+	remote_ip = ssh_remote_ipaddr(ssh);
+
+#ifdef SSH_AUDIT_EVENTS
+	audit_connection_from(remote_ip, remote_port);
+#endif
+
+	rdomain = ssh_packet_rdomain_in(ssh);
+
+	/* Log the connection. */
+	laddr = get_local_ipaddr(sock_in);
+	verbose("Connection from %s port %d on %s port %d%s%s%s",
+	    remote_ip, remote_port, laddr,  ssh_local_port(ssh),
+	    rdomain == NULL ? "" : " rdomain \"",
+	    rdomain == NULL ? "" : rdomain,
+	    rdomain == NULL ? "" : "\"");
+	free(laddr);
+
+	/*
+	 * We don't want to listen forever unless the other side
+	 * successfully authenticates itself.  So we set up an alarm which is
+	 * cleared after successful authentication.  A limit of zero
+	 * indicates no limit. Note that we don't set the alarm in debugging
+	 * mode; it is just annoying to have the server exit just when you
+	 * are about to discover the bug.
+	 */
+	signal(SIGALRM, grace_alarm_handler);
+	if (!debug_flag)
+		alarm(options.login_grace_time);
+
+	sshd_exchange_identification(ssh, sock_in, sock_out);
+	packet_set_nonblocking();
+
+	/* allocate authentication context */
+	authctxt = xcalloc(1, sizeof(*authctxt));
+
+	authctxt->loginmsg = loginmsg;
+
+	/* XXX global for cleanup, access from other modules */
+	the_authctxt = authctxt;
+
+	/* Set default key authentication options */
+	if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
+		fatal("allocation failed");
+
+	/* prepare buffer to collect messages to display to user after login */
+	if ((loginmsg = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	auth_debug_reset();
+
+	if (use_privsep) {
+		if (privsep_preauth(authctxt) == 1)
+			goto authenticated;
+	} else if (have_agent) {
+		if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
+			error("Unable to get agent socket: %s", ssh_err(r));
+			have_agent = 0;
+		}
+	}
+
+	/* perform the key exchange */
+	/* authenticate user and start session */
+	do_ssh2_kex();
+	do_authentication2(authctxt);
+
+	/*
+	 * If we use privilege separation, the unprivileged child transfers
+	 * the current keystate and exits
+	 */
+	if (use_privsep) {
+		mm_send_keystate(pmonitor);
+		packet_clear_keys();
+		exit(0);
+	}
+
+ authenticated:
+	/*
+	 * Cancel the alarm we set to limit the time taken for
+	 * authentication.
+	 */
+	alarm(0);
+	signal(SIGALRM, SIG_DFL);
+	authctxt->authenticated = 1;
+	if (startup_pipe != -1) {
+		close(startup_pipe);
+		startup_pipe = -1;
+	}
+
+#ifdef SSH_AUDIT_EVENTS
+	audit_event(SSH_AUTH_SUCCESS);
+#endif
+
+#ifdef GSSAPI
+	if (options.gss_authentication) {
+		temporarily_use_uid(authctxt->pw);
+		ssh_gssapi_storecreds();
+		restore_uid();
+	}
+#endif
+#ifdef USE_PAM
+	if (options.use_pam) {
+		do_pam_setcred(1);
+		do_pam_session(ssh);
+	}
+#endif
+
+	/*
+	 * In privilege separation, we fork another child and prepare
+	 * file descriptor passing.
+	 */
+	if (use_privsep) {
+		privsep_postauth(authctxt);
+		/* the monitor process [priv] will not return */
+	}
+
+	packet_set_timeout(options.client_alive_interval,
+	    options.client_alive_count_max);
+
+	/* Try to send all our hostkeys to the client */
+	notify_hostkeys(ssh);
+
+	/* Start session. */
+	do_authenticated(ssh, authctxt);
+
+	/* The connection has been terminated. */
+	packet_get_bytes(&ibytes, &obytes);
+	verbose("Transferred: sent %llu, received %llu bytes",
+	    (unsigned long long)obytes, (unsigned long long)ibytes);
+
+	verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
+
+#ifdef USE_PAM
+	if (options.use_pam)
+		finish_pam();
+#endif /* USE_PAM */
+
+#ifdef SSH_AUDIT_EVENTS
+	PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
+#endif
+
+	packet_close();
+
+	if (use_privsep)
+		mm_terminate();
+
+	exit(0);
+}
+
+int
+sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey,
+    u_char **signature, size_t *slenp, const u_char *data, size_t dlen,
+    const char *alg, u_int flag)
+{
+	int r;
+
+	if (privkey) {
+		if (PRIVSEP(sshkey_sign(privkey, signature, slenp, data, dlen,
+		    alg, datafellows)) < 0)
+			fatal("%s: key_sign failed", __func__);
+	} else if (use_privsep) {
+		if (mm_sshkey_sign(pubkey, signature, slenp, data, dlen,
+		    alg, datafellows) < 0)
+			fatal("%s: pubkey_sign failed", __func__);
+	} else {
+		if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slenp,
+		    data, dlen, alg, datafellows)) != 0)
+			fatal("%s: ssh_agent_sign failed: %s",
+			    __func__, ssh_err(r));
+	}
+	return 0;
+}
+
+/* SSH2 key exchange */
+static void
+do_ssh2_kex(void)
+{
+	char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
+	struct kex *kex;
+	int r;
+
+	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
+	    options.kex_algorithms);
+	myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
+	    options.ciphers);
+	myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
+	    options.ciphers);
+	myproposal[PROPOSAL_MAC_ALGS_CTOS] =
+	    myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
+
+	if (options.compression == COMP_NONE) {
+		myproposal[PROPOSAL_COMP_ALGS_CTOS] =
+		    myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
+	}
+
+	if (options.rekey_limit || options.rekey_interval)
+		packet_set_rekey_limits(options.rekey_limit,
+		    options.rekey_interval);
+
+	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
+	    list_hostkey_types());
+
+	/* start key exchange */
+	if ((r = kex_setup(active_state, myproposal)) != 0)
+		fatal("kex_setup: %s", ssh_err(r));
+	kex = active_state->kex;
+#ifdef WITH_OPENSSL
+	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
+	kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
+	kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
+	kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
+	kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
+	kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
+	kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
+# ifdef OPENSSL_HAS_ECC
+	kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
+# endif
+#endif
+	kex->kex[KEX_C25519_SHA256] = kexc25519_server;
+	kex->server = 1;
+	kex->client_version_string=client_version_string;
+	kex->server_version_string=server_version_string;
+	kex->load_host_public_key=&get_hostkey_public_by_type;
+	kex->load_host_private_key=&get_hostkey_private_by_type;
+	kex->host_key_index=&get_hostkey_index;
+	kex->sign = sshd_hostkey_sign;
+
+	ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
+
+	session_id2 = kex->session_id;
+	session_id2_len = kex->session_id_len;
+
+#ifdef DEBUG_KEXDH
+	/* send 1st encrypted/maced/compressed message */
+	packet_start(SSH2_MSG_IGNORE);
+	packet_put_cstring("markus");
+	packet_send();
+	packet_write_wait();
+#endif
+	debug("KEX done");
+}
+
+/* server specific fatal cleanup */
+void
+cleanup_exit(int i)
+{
+	struct ssh *ssh = active_state; /* XXX */
+
+	if (the_authctxt) {
+		do_cleanup(ssh, the_authctxt);
+		if (use_privsep && privsep_is_preauth &&
+		    pmonitor != NULL && pmonitor->m_pid > 1) {
+			debug("Killing privsep child %d", pmonitor->m_pid);
+			if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
+			    errno != ESRCH)
+				error("%s: kill(%d): %s", __func__,
+				    pmonitor->m_pid, strerror(errno));
+		}
+	}
+#ifdef SSH_AUDIT_EVENTS
+	/* done after do_cleanup so it can cancel the PAM auth 'thread' */
+	if (!use_privsep || mm_is_monitor())
+		audit_event(SSH_CONNECTION_ABANDON);
+#endif
+	_exit(i);
+}