Merging upstream version 1:9.8p1.

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

1 files changed, 1500 insertions, 0 deletions

diff --git a/sshd-session.c b/sshd-session.c
new file mode 100644
index 0000000..fe6ae7f
--- /dev/null
+++ b/sshd-session.c
@@ -0,0 +1,1500 @@
+/* $OpenBSD: sshd-session.c,v 1.4 2024/06/26 23:16:52 deraadt Exp $ */
+/*
+ * 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 <pwd.h>
+#include <grp.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <limits.h>
+
+#ifdef WITH_OPENSSL
+#include <openssl/bn.h>
+#include <openssl/evp.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 "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"
+#include "sk-api.h"
+#include "srclimit.h"
+#include "dh.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;
+
+/* Flag indicating that the daemon is being started from inetd. */
+static int inetd_flag = 0;
+
+/* debug goes to stderr unless inetd_flag is set */
+static int log_stderr = 0;
+
+/* Saved arguments to main(). */
+static char **saved_argv;
+static int saved_argc;
+
+/* Daemon's agent connection */
+int auth_sock = -1;
+static 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 {
+	u_int		num_hostkeys;
+	struct sshkey	**host_keys;		/* all private host keys */
+	struct sshkey	**host_pubkeys;		/* all public host keys */
+	struct sshkey	**host_certificates;	/* all public host certificates */
+} sensitive_data;
+
+/* record remote hostname or ip */
+u_int utmp_len = HOST_NAME_MAX+1;
+
+static int startup_pipe = -1;		/* in child */
+
+/* variables used for privilege separation */
+struct monitor *pmonitor = NULL;
+int privsep_is_preauth = 1;
+static int privsep_chroot = 1;
+
+/* Unprivileged user */
+struct passwd *privsep_pw = NULL;
+
+/* global connection state and authentication contexts */
+Authctxt *the_authctxt = NULL;
+struct ssh *the_active_state;
+
+/* global key/cert auth options. XXX move to permanent ssh->authctxt? */
+struct sshauthopt *auth_opts = NULL;
+
+/* sshd_config buffer */
+struct sshbuf *cfg;
+
+/* Included files from the configuration file */
+struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
+
+/* message to be displayed after login */
+struct sshbuf *loginmsg;
+
+/* Prototypes for various functions defined later in this file. */
+void destroy_sensitive_data(void);
+void demote_sensitive_data(void);
+static void do_ssh2_kex(struct ssh *);
+
+/*
+ * Signal handler for the alarm after the login grace period has expired.
+ * As usual, this may only take signal-safe actions, even though it is
+ * terminal.
+ */
+static void
+grace_alarm_handler(int sig)
+{
+	/*
+	 * Try to kill any processes that we have spawned, E.g. authorized
+	 * keys command helpers or privsep children.
+	 */
+	if (getpgid(0) == getpid()) {
+		struct sigaction sa;
+
+		/* mask all other signals while in handler */
+		memset(&sa, 0, sizeof(sa));
+		sa.sa_handler = SIG_IGN;
+		sigfillset(&sa.sa_mask);
+		sa.sa_flags = SA_RESTART;
+		(void)sigaction(SIGTERM, &sa, NULL);
+		kill(0, SIGTERM);
+	}
+	_exit(EXIT_LOGIN_GRACE);
+}
+
+/* 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_r(r, "could not demote host %s key",
+				    sshkey_type(sensitive_data.host_keys[i]));
+			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) == -1)
+			fatal("setgroups: %.100s", strerror(errno));
+		permanently_set_uid(privsep_pw);
+	}
+}
+
+static int
+privsep_preauth(struct ssh *ssh)
+{
+	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 = &ssh->kex;
+
+	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_r(r, "Could not get agent socket");
+				have_agent = 0;
+			}
+		}
+		if (box != NULL)
+			ssh_sandbox_parent_preauth(box, pid);
+		monitor_child_preauth(ssh, pmonitor);
+
+		/* Wait for the child's exit status */
+		while (waitpid(pid, &status, 0) == -1) {
+			if (errno == EINTR)
+				continue;
+			pmonitor->m_pid = -1;
+			fatal_f("waitpid: %s", strerror(errno));
+		}
+		privsep_is_preauth = 0;
+		pmonitor->m_pid = -1;
+		if (WIFEXITED(status)) {
+			if (WEXITSTATUS(status) != 0)
+				fatal_f("preauth child exited with status %d",
+				    WEXITSTATUS(status));
+		} else if (WIFSIGNALED(status))
+			fatal_f("preauth child terminated by signal %d",
+			    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(struct ssh *ssh, Authctxt *authctxt)
+{
+	int skip_privdrop = 0;
+
+	/*
+	 * Hack for systems that don't support FD passing: retain privileges
+	 * in the post-auth privsep process so it can allocate PTYs directly.
+	 * This is basically equivalent to what we did <= 9.7, which was to
+	 * disable post-auth privsep entriely.
+	 * Cygwin doesn't need to drop privs here although it doesn't support
+	 * fd passing, as AFAIK PTY allocation on this platform doesn't require
+	 * special privileges to begin with.
+	 */
+#if defined(DISABLE_FD_PASSING) && !defined(HAVE_CYGWIN)
+	skip_privdrop = 1;
+#endif
+
+	/* 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(ssh, pmonitor);
+		monitor_child_postauth(ssh, 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 */
+	if (!skip_privdrop)
+		do_setusercontext(authctxt->pw);
+
+	/* It is safe now to apply the key state */
+	monitor_apply_keystate(ssh, pmonitor);
+
+	/*
+	 * Tell the packet layer that authentication was successful, since
+	 * this information is not part of the key state.
+	 */
+	ssh_packet_set_authenticated(ssh);
+}
+
+static void
+append_hostkey_type(struct sshbuf *b, const char *s)
+{
+	int r;
+
+	if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
+		debug3_f("%s key not permitted by HostkeyAlgorithms", s);
+		return;
+	}
+	if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
+		fatal_fr(r, "sshbuf_putf");
+}
+
+static char *
+list_hostkey_types(void)
+{
+	struct sshbuf *b;
+	struct sshkey *key;
+	char *ret;
+	u_int i;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+	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_ECDSA_SK:
+		case KEY_ED25519_SK:
+		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_ECDSA_SK_CERT:
+		case KEY_ED25519_SK_CERT:
+		case KEY_XMSS_CERT:
+			append_hostkey_type(b, sshkey_ssh_name(key));
+			break;
+		}
+	}
+	if ((ret = sshbuf_dup_string(b)) == NULL)
+		fatal_f("sshbuf_dup_string failed");
+	sshbuf_free(b);
+	debug_f("%s", 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_ECDSA_SK_CERT:
+		case KEY_ED25519_SK_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)
+			continue;
+		switch (type) {
+		case KEY_ECDSA:
+		case KEY_ECDSA_SK:
+		case KEY_ECDSA_CERT:
+		case KEY_ECDSA_SK_CERT:
+			if (key->ecdsa_nid != nid)
+				continue;
+			/* FALLTHROUGH */
+		default:
+			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 (ssh->compat & SSH_BUG_HOSTKEYS)
+		return;
+
+	if ((buf = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new");
+	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_f("key %d: %s %s", i, sshkey_ssh_name(key), fp);
+		free(fp);
+		if (nkeys == 0) {
+			/*
+			 * Start building the request when we find the
+			 * first usable key.
+			 */
+			if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+			    (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 ||
+			    (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */
+				sshpkt_fatal(ssh, r, "%s: start request", __func__);
+		}
+		/* Append the key to the request */
+		sshbuf_reset(buf);
+		if ((r = sshkey_putb(key, buf)) != 0)
+			fatal_fr(r, "couldn't put hostkey %d", i);
+		if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
+			sshpkt_fatal(ssh, r, "%s: append key", __func__);
+		nkeys++;
+	}
+	debug3_f("sent %u hostkeys", nkeys);
+	if (nkeys == 0)
+		fatal_f("no hostkeys");
+	if ((r = sshpkt_send(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: send", __func__);
+	sshbuf_free(buf);
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr, "%s, %s\n", SSH_RELEASE, SSH_OPENSSL_VERSION);
+	fprintf(stderr,
+"usage: sshd [-46DdeGiqTtV] [-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
+parse_hostkeys(struct sshbuf *hostkeys)
+{
+	int r;
+	u_int num_keys = 0;
+	struct sshkey *k;
+	struct sshbuf *kbuf;
+	const u_char *cp;
+	size_t len;
+
+	while (sshbuf_len(hostkeys) != 0) {
+		if (num_keys > 2048)
+			fatal_f("too many hostkeys");
+		sensitive_data.host_keys = xrecallocarray(
+		    sensitive_data.host_keys, num_keys, num_keys + 1,
+		    sizeof(*sensitive_data.host_pubkeys));
+		sensitive_data.host_pubkeys = xrecallocarray(
+		    sensitive_data.host_pubkeys, num_keys, num_keys + 1,
+		    sizeof(*sensitive_data.host_pubkeys));
+		sensitive_data.host_certificates = xrecallocarray(
+		    sensitive_data.host_certificates, num_keys, num_keys + 1,
+		    sizeof(*sensitive_data.host_certificates));
+		/* private key */
+		k = NULL;
+		if ((r = sshbuf_froms(hostkeys, &kbuf)) != 0)
+			fatal_fr(r, "extract privkey");
+		if (sshbuf_len(kbuf) != 0 &&
+		    (r = sshkey_private_deserialize(kbuf, &k)) != 0)
+			fatal_fr(r, "parse pubkey");
+		sensitive_data.host_keys[num_keys] = k;
+		sshbuf_free(kbuf);
+		if (k)
+			debug2_f("privkey %u: %s", num_keys, sshkey_ssh_name(k));
+		/* public key */
+		k = NULL;
+		if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
+			fatal_fr(r, "extract pubkey");
+		if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
+			fatal_fr(r, "parse pubkey");
+		sensitive_data.host_pubkeys[num_keys] = k;
+		if (k)
+			debug2_f("pubkey %u: %s", num_keys, sshkey_ssh_name(k));
+		/* certificate */
+		k = NULL;
+		if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
+			fatal_fr(r, "extract pubkey");
+		if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
+			fatal_fr(r, "parse pubkey");
+		sensitive_data.host_certificates[num_keys] = k;
+		if (k)
+			debug2_f("cert %u: %s", num_keys, sshkey_ssh_name(k));
+		num_keys++;
+	}
+	sensitive_data.num_hostkeys = num_keys;
+}
+
+static void
+recv_rexec_state(int fd, struct sshbuf *conf, uint64_t *timing_secretp)
+{
+	struct sshbuf *m, *inc, *hostkeys;
+	u_char *cp, ver;
+	size_t len;
+	int r;
+	struct include_item *item;
+
+	debug3_f("entering fd = %d", fd);
+
+	if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+	if (ssh_msg_recv(fd, m) == -1)
+		fatal_f("ssh_msg_recv failed");
+	if ((r = sshbuf_get_u8(m, &ver)) != 0)
+		fatal_fr(r, "parse version");
+	if (ver != 0)
+		fatal_f("rexec version mismatch");
+	if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || /* XXX _direct */
+	    (r = sshbuf_get_u64(m, timing_secretp)) != 0 ||
+	    (r = sshbuf_froms(m, &hostkeys)) != 0 ||
+	    (r = sshbuf_get_stringb(m, inc)) != 0)
+		fatal_fr(r, "parse config");
+
+	if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
+		fatal_fr(r, "sshbuf_put");
+
+	while (sshbuf_len(inc) != 0) {
+		item = xcalloc(1, sizeof(*item));
+		if ((item->contents = sshbuf_new()) == NULL)
+			fatal_f("sshbuf_new failed");
+		if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 ||
+		    (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 ||
+		    (r = sshbuf_get_stringb(inc, item->contents)) != 0)
+			fatal_fr(r, "parse includes");
+		TAILQ_INSERT_TAIL(&includes, item, entry);
+	}
+
+	parse_hostkeys(hostkeys);
+
+	free(cp);
+	sshbuf_free(m);
+	sshbuf_free(hostkeys);
+	sshbuf_free(inc);
+
+	debug3_f("done");
+}
+
+/*
+ * 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) == -1)
+		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_f("set routing domain %d (was %d)", rtable, ortable);
+#else /* defined(__OpenBSD__) */
+	fatal("Unable to set routing domain: not supported in this platform");
+#endif
+}
+
+/*
+ * 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, remote_port;
+	int sock_in = -1, sock_out = -1, rexeced_flag = 0, have_key = 0;
+	const char *remote_ip, *rdomain;
+	char *line, *laddr, *logfile = NULL;
+	u_int i;
+	u_int64_t ibytes, obytes;
+	mode_t new_umask;
+	Authctxt *authctxt;
+	struct connection_info *connection_info = NULL;
+	sigset_t sigmask;
+	uint64_t timing_secret = 0;
+
+	sigemptyset(&sigmask);
+	sigprocmask(SIG_SETMASK, &sigmask, NULL);
+
+#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;
+	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
+
+	/* 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:46DGQRTdeiqrtV")) != -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':
+			/* ignore */
+			break;
+		case 'E':
+			logfile = optarg;
+			/* FALLTHROUGH */
+		case 'e':
+			log_stderr = 1;
+			break;
+		case 'i':
+			inetd_flag = 1;
+			break;
+		case 'r':
+			/* ignore */
+			break;
+		case 'R':
+			rexeced_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, 1);
+			break;
+		case 't':
+		case 'T':
+		case 'G':
+			fatal("test/dump modes not supported");
+			break;
+		case 'C':
+			connection_info = server_get_connection_info(ssh, 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, &includes) != 0)
+				exit(1);
+			free(line);
+			break;
+		case 'V':
+			fprintf(stderr, "%s, %s\n",
+			    SSH_RELEASE, SSH_OPENSSL_VERSION);
+			exit(0);
+		default:
+			usage();
+			break;
+		}
+	}
+
+	/* 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, SSH_OPENSSL_VERSION);
+
+	if (!rexeced_flag)
+		fatal("sshd-session should not be executed directly");
+
+	closefrom(REEXEC_MIN_FREE_FD);
+
+	seed_rng();
+
+	/* If requested, redirect the logs to the specified logfile. */
+	if (logfile != NULL) {
+		char *cp, pid_s[32];
+
+		snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid());
+		cp = percent_expand(logfile,
+		    "p", pid_s,
+		    "P", "sshd-session",
+		    (char *)NULL);
+		log_redirect_stderr_to(cp);
+		free(cp);
+	}
+
+	/*
+	 * 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 || debug_flag);
+
+	debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
+
+	/* Fetch our configuration */
+	if ((cfg = sshbuf_new()) == NULL)
+		fatal("sshbuf_new config buf failed");
+	setproctitle("%s", "[rexeced]");
+	recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg, &timing_secret);
+	close(REEXEC_CONFIG_PASS_FD);
+	parse_server_config(&options, "rexec", cfg, &includes, NULL, 1);
+	/* Fill in default values for those options not explicitly set. */
+	fill_default_server_options(&options);
+	options.timing_secret = timing_secret;
+
+	/* Store privilege separation user for later use if required. */
+	privsep_chroot = (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();
+
+	if (!debug_flag) {
+		startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
+		close(REEXEC_STARTUP_PIPE_FD);
+		/*
+		 * Signal parent that this child is at a point where
+		 * they can go away if they have a SIGHUP pending.
+		 */
+		(void)atomicio(vwrite, startup_pipe, "\0", 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");
+	}
+
+#ifdef WITH_OPENSSL
+	if (options.moduli_file != NULL)
+		dh_set_moduli_file(options.moduli_file);
+#endif
+
+	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_r(r, "Could not connect to agent \"%s\"",
+			    options.host_key_agent);
+	}
+
+	if (options.num_host_key_files != sensitive_data.num_hostkeys) {
+		fatal("internal error: hostkeys confused (config %u recvd %u)",
+		    options.num_host_key_files, sensitive_data.num_hostkeys);
+	}
+
+	for (i = 0; i < options.num_host_key_files; i++) {
+		if (sensitive_data.host_keys[i] != NULL ||
+		    (have_agent && sensitive_data.host_pubkeys[i] != NULL)) {
+			have_key = 1;
+			break;
+		}
+	}
+	if (!have_key)
+		fatal("internal error: monitor received no hostkeys");
+
+	/* 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)
+		log_stderr = 1;
+	log_init(__progname, options.log_level,
+	    options.log_facility, log_stderr);
+	for (i = 0; i < options.num_log_verbose; i++)
+		log_verbose_add(options.log_verbose[i]);
+
+	/* 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 */
+	ssh_signal(SIGPIPE, SIG_IGN);
+
+	/* Get a connection, either from inetd or rexec */
+	if (inetd_flag) {
+		/*
+		 * NB. must be different fd numbers for the !socket case,
+		 * as packet_connection_is_on_socket() depends on this.
+		 */
+		sock_in = dup(STDIN_FILENO);
+		sock_out = dup(STDOUT_FILENO);
+	} else {
+		/* rexec case; accept()ed socket in ancestor listener */
+		sock_in = sock_out = dup(STDIN_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 (stdfd_devnull(1, 1, !log_stderr) == -1)
+		error("stdfd_devnull failed");
+	debug("network sockets: %d, %d", sock_in, sock_out);
+
+	/* This is the child processing a new connection. */
+	setproctitle("%s", "[accepted]");
+
+	/* Executed child processes don't need these. */
+	fcntl(sock_out, F_SETFD, FD_CLOEXEC);
+	fcntl(sock_in, F_SETFD, FD_CLOEXEC);
+
+	/* We will not restart on SIGHUP since it no longer makes sense. */
+	ssh_signal(SIGALRM, SIG_DFL);
+	ssh_signal(SIGHUP, SIG_DFL);
+	ssh_signal(SIGTERM, SIG_DFL);
+	ssh_signal(SIGQUIT, SIG_DFL);
+	ssh_signal(SIGCHLD, SIG_DFL);
+	ssh_signal(SIGINT, SIG_DFL);
+
+	/*
+	 * Register our connection.  This turns encryption off because we do
+	 * not have a key.
+	 */
+	if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL)
+		fatal("Unable to create connection");
+	the_active_state = ssh;
+	ssh_packet_set_server(ssh);
+
+	check_ip_options(ssh);
+
+	/* Prepare the channels layer */
+	channel_init_channels(ssh);
+	channel_set_af(ssh, options.address_family);
+	server_process_channel_timeouts(ssh);
+	server_process_permitopen(ssh);
+
+	/* Set SO_KEEPALIVE if requested. */
+	if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) &&
+	    setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1)
+		error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
+
+	if ((remote_port = ssh_remote_port(ssh)) < 0) {
+		debug("ssh_remote_port failed");
+		cleanup_exit(255);
+	}
+
+	/*
+	 * 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.
+	 */
+	ssh_signal(SIGALRM, grace_alarm_handler);
+	if (!debug_flag)
+		alarm(options.login_grace_time);
+
+	if ((r = kex_exchange_identification(ssh, -1,
+	    options.version_addendum)) != 0)
+		sshpkt_fatal(ssh, r, "banner exchange");
+
+	ssh_packet_set_nonblocking(ssh);
+
+	/* allocate authentication context */
+	authctxt = xcalloc(1, sizeof(*authctxt));
+	ssh->authctxt = authctxt;
+
+	/* 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("sshbuf_new loginmsg failed");
+	auth_debug_reset();
+
+	if (privsep_preauth(ssh) == 1)
+		goto authenticated;
+
+	/* perform the key exchange */
+	/* authenticate user and start session */
+	do_ssh2_kex(ssh);
+	do_authentication2(ssh);
+
+	/*
+	 * The unprivileged child now transfers the current keystate and exits.
+	 */
+	mm_send_keystate(ssh, pmonitor);
+	ssh_packet_clear_keys(ssh);
+	exit(0);
+
+ authenticated:
+	/*
+	 * Cancel the alarm we set to limit the time taken for
+	 * authentication.
+	 */
+	alarm(0);
+	ssh_signal(SIGALRM, SIG_DFL);
+	authctxt->authenticated = 1;
+	if (startup_pipe != -1) {
+		/* signal listener that authentication completed successfully */
+		(void)atomicio(vwrite, startup_pipe, "\001", 1);
+		close(startup_pipe);
+		startup_pipe = -1;
+	}
+
+	if (options.routing_domain != NULL)
+		set_process_rdomain(ssh, options.routing_domain);
+
+#ifdef SSH_AUDIT_EVENTS
+	audit_event(ssh, 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();
+		do_pam_session(ssh);
+	}
+#endif
+
+	/*
+	 * In privilege separation, we fork another child and prepare
+	 * file descriptor passing.
+	 */
+	privsep_postauth(ssh, authctxt);
+	/* the monitor process [priv] will not return */
+
+	ssh_packet_set_timeout(ssh, 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. */
+	ssh_packet_get_bytes(ssh, &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
+	mm_audit_event(ssh, SSH_CONNECTION_CLOSE);
+#endif
+
+	ssh_packet_close(ssh);
+
+	mm_terminate();
+
+	exit(0);
+}
+
+int
+sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
+    struct sshkey *pubkey, u_char **signature, size_t *slenp,
+    const u_char *data, size_t dlen, const char *alg)
+{
+	if (privkey) {
+		if (mm_sshkey_sign(ssh, privkey, signature, slenp,
+		    data, dlen, alg, options.sk_provider, NULL,
+		    ssh->compat) < 0)
+			fatal_f("privkey sign failed");
+	} else {
+		if (mm_sshkey_sign(ssh, pubkey, signature, slenp,
+		    data, dlen, alg, options.sk_provider, NULL,
+		    ssh->compat) < 0)
+			fatal_f("pubkey sign failed");
+	}
+	return 0;
+}
+
+/* SSH2 key exchange */
+static void
+do_ssh2_kex(struct ssh *ssh)
+{
+	char *hkalgs = NULL, *myproposal[PROPOSAL_MAX];
+	const char *compression = NULL;
+	struct kex *kex;
+	int r;
+
+	if (options.rekey_limit || options.rekey_interval)
+		ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
+		    options.rekey_interval);
+
+	if (options.compression == COMP_NONE)
+		compression = "none";
+	hkalgs = list_hostkey_types();
+
+	kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms,
+	    options.ciphers, options.macs, compression, hkalgs);
+
+	free(hkalgs);
+
+	/* start key exchange */
+	if ((r = kex_setup(ssh, myproposal)) != 0)
+		fatal_r(r, "kex_setup");
+	kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos);
+	kex = ssh->kex;
+
+#ifdef WITH_OPENSSL
+	kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
+	kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
+	kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
+	kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
+	kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_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] = kex_gen_server;
+ #endif
+#endif
+	kex->kex[KEX_C25519_SHA256] = kex_gen_server;
+	kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
+	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(ssh, DISPATCH_BLOCK, &kex->done);
+	kex_proposal_free_entries(myproposal);
+
+#ifdef DEBUG_KEXDH
+	/* send 1st encrypted/maced/compressed message */
+	if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0 ||
+	    (r = ssh_packet_write_wait(ssh)) != 0)
+		fatal_fr(r, "send test");
+#endif
+	debug("KEX done");
+}
+
+/* server specific fatal cleanup */
+void
+cleanup_exit(int i)
+{
+	extern int auth_attempted; /* monitor.c */
+
+	if (the_active_state != NULL && the_authctxt != NULL) {
+		do_cleanup(the_active_state, the_authctxt);
+		if (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_f("kill(%d): %s", pmonitor->m_pid,
+				    strerror(errno));
+			}
+		}
+	}
+	/* Override default fatal exit value when auth was attempted */
+	if (i == 255 && auth_attempted)
+		_exit(EXIT_AUTH_ATTEMPTED);
+#ifdef SSH_AUDIT_EVENTS
+	/* done after do_cleanup so it can cancel the PAM auth 'thread' */
+	if (the_active_state != NULL && mm_is_monitor())
+		audit_event(the_active_state, SSH_CONNECTION_ABANDON);
+#endif
+	_exit(i);
+}