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

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

1 files changed, 921 insertions, 0 deletions

diff --git a/serverloop.c b/serverloop.c
new file mode 100644
index 0000000..7be83e2
--- /dev/null
+++ b/serverloop.c
@@ -0,0 +1,921 @@
+/* $OpenBSD: serverloop.c,v 1.209 2018/07/27 05:13:02 dtucker Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * Server main loop for handling the interactive session.
+ *
+ * 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 support by Markus Friedl.
+ * Copyright (c) 2000, 2001 Markus Friedl.  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/wait.h>
+#include <sys/socket.h>
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+
+#include <netinet/in.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <signal.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+#include <stdarg.h>
+
+#include "openbsd-compat/sys-queue.h"
+#include "xmalloc.h"
+#include "packet.h"
+#include "sshbuf.h"
+#include "log.h"
+#include "misc.h"
+#include "servconf.h"
+#include "canohost.h"
+#include "sshpty.h"
+#include "channels.h"
+#include "compat.h"
+#include "ssh2.h"
+#include "sshkey.h"
+#include "cipher.h"
+#include "kex.h"
+#include "hostfile.h"
+#include "auth.h"
+#include "session.h"
+#include "dispatch.h"
+#include "auth-options.h"
+#include "serverloop.h"
+#include "ssherr.h"
+
+extern ServerOptions options;
+
+/* XXX */
+extern Authctxt *the_authctxt;
+extern struct sshauthopt *auth_opts;
+extern int use_privsep;
+
+static int no_more_sessions = 0; /* Disallow further sessions. */
+
+/*
+ * This SIGCHLD kludge is used to detect when the child exits.  The server
+ * will exit after that, as soon as forwarded connections have terminated.
+ */
+
+static volatile sig_atomic_t child_terminated = 0;	/* The child has terminated. */
+
+/* Cleanup on signals (!use_privsep case only) */
+static volatile sig_atomic_t received_sigterm = 0;
+
+/* prototypes */
+static void server_init_dispatch(void);
+
+/* requested tunnel forwarding interface(s), shared with session.c */
+char *tun_fwd_ifnames = NULL;
+
+/* returns 1 if bind to specified port by specified user is permitted */
+static int
+bind_permitted(int port, uid_t uid)
+{
+	if (use_privsep)
+		return 1; /* allow system to decide */
+	if (port < IPPORT_RESERVED && uid != 0)
+		return 0;
+	return 1;
+}
+
+/*
+ * we write to this pipe if a SIGCHLD is caught in order to avoid
+ * the race between select() and child_terminated
+ */
+static int notify_pipe[2];
+static void
+notify_setup(void)
+{
+	if (pipe(notify_pipe) < 0) {
+		error("pipe(notify_pipe) failed %s", strerror(errno));
+	} else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) ||
+	    (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) {
+		error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
+		close(notify_pipe[0]);
+		close(notify_pipe[1]);
+	} else {
+		set_nonblock(notify_pipe[0]);
+		set_nonblock(notify_pipe[1]);
+		return;
+	}
+	notify_pipe[0] = -1;	/* read end */
+	notify_pipe[1] = -1;	/* write end */
+}
+static void
+notify_parent(void)
+{
+	if (notify_pipe[1] != -1)
+		(void)write(notify_pipe[1], "", 1);
+}
+static void
+notify_prepare(fd_set *readset)
+{
+	if (notify_pipe[0] != -1)
+		FD_SET(notify_pipe[0], readset);
+}
+static void
+notify_done(fd_set *readset)
+{
+	char c;
+
+	if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
+		while (read(notify_pipe[0], &c, 1) != -1)
+			debug2("%s: reading", __func__);
+}
+
+/*ARGSUSED*/
+static void
+sigchld_handler(int sig)
+{
+	int save_errno = errno;
+	child_terminated = 1;
+	notify_parent();
+	errno = save_errno;
+}
+
+/*ARGSUSED*/
+static void
+sigterm_handler(int sig)
+{
+	received_sigterm = sig;
+}
+
+static void
+client_alive_check(struct ssh *ssh)
+{
+	int channel_id;
+	char remote_id[512];
+
+	/* timeout, check to see how many we have had */
+	if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
+		sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
+		logit("Timeout, client not responding from %s", remote_id);
+		cleanup_exit(255);
+	}
+
+	/*
+	 * send a bogus global/channel request with "wantreply",
+	 * we should get back a failure
+	 */
+	if ((channel_id = channel_find_open(ssh)) == -1) {
+		packet_start(SSH2_MSG_GLOBAL_REQUEST);
+		packet_put_cstring("keepalive@openssh.com");
+		packet_put_char(1);	/* boolean: want reply */
+	} else {
+		channel_request_start(ssh, channel_id,
+		    "keepalive@openssh.com", 1);
+	}
+	packet_send();
+}
+
+/*
+ * Sleep in select() until we can do something.  This will initialize the
+ * select masks.  Upon return, the masks will indicate which descriptors
+ * have data or can accept data.  Optionally, a maximum time can be specified
+ * for the duration of the wait (0 = infinite).
+ */
+static void
+wait_until_can_do_something(struct ssh *ssh,
+    int connection_in, int connection_out,
+    fd_set **readsetp, fd_set **writesetp, int *maxfdp,
+    u_int *nallocp, u_int64_t max_time_ms)
+{
+	struct timeval tv, *tvp;
+	int ret;
+	time_t minwait_secs = 0;
+	int client_alive_scheduled = 0;
+	static time_t last_client_time;
+
+	/* Allocate and update select() masks for channel descriptors. */
+	channel_prepare_select(ssh, readsetp, writesetp, maxfdp,
+	    nallocp, &minwait_secs);
+
+	/* XXX need proper deadline system for rekey/client alive */
+	if (minwait_secs != 0)
+		max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000);
+
+	/*
+	 * if using client_alive, set the max timeout accordingly,
+	 * and indicate that this particular timeout was for client
+	 * alive by setting the client_alive_scheduled flag.
+	 *
+	 * this could be randomized somewhat to make traffic
+	 * analysis more difficult, but we're not doing it yet.
+	 */
+	if (options.client_alive_interval) {
+		uint64_t keepalive_ms =
+		    (uint64_t)options.client_alive_interval * 1000;
+
+		client_alive_scheduled = 1;
+		if (max_time_ms == 0 || max_time_ms > keepalive_ms)
+			max_time_ms = keepalive_ms;
+	}
+
+#if 0
+	/* wrong: bad condition XXX */
+	if (channel_not_very_much_buffered_data())
+#endif
+	FD_SET(connection_in, *readsetp);
+	notify_prepare(*readsetp);
+
+	/*
+	 * If we have buffered packet data going to the client, mark that
+	 * descriptor.
+	 */
+	if (packet_have_data_to_write())
+		FD_SET(connection_out, *writesetp);
+
+	/*
+	 * If child has terminated and there is enough buffer space to read
+	 * from it, then read as much as is available and exit.
+	 */
+	if (child_terminated && packet_not_very_much_data_to_write())
+		if (max_time_ms == 0 || client_alive_scheduled)
+			max_time_ms = 100;
+
+	if (max_time_ms == 0)
+		tvp = NULL;
+	else {
+		tv.tv_sec = max_time_ms / 1000;
+		tv.tv_usec = 1000 * (max_time_ms % 1000);
+		tvp = &tv;
+	}
+
+	/* Wait for something to happen, or the timeout to expire. */
+	ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
+
+	if (ret == -1) {
+		memset(*readsetp, 0, *nallocp);
+		memset(*writesetp, 0, *nallocp);
+		if (errno != EINTR)
+			error("select: %.100s", strerror(errno));
+	} else if (client_alive_scheduled) {
+		time_t now = monotime();
+
+		if (ret == 0) { /* timeout */
+			client_alive_check(ssh);
+		} else if (FD_ISSET(connection_in, *readsetp)) {
+			last_client_time = now;
+		} else if (last_client_time != 0 && last_client_time +
+		    options.client_alive_interval <= now) {
+			client_alive_check(ssh);
+			last_client_time = now;
+		}
+	}
+
+	notify_done(*readsetp);
+}
+
+/*
+ * Processes input from the client and the program.  Input data is stored
+ * in buffers and processed later.
+ */
+static int
+process_input(struct ssh *ssh, fd_set *readset, int connection_in)
+{
+	int len;
+	char buf[16384];
+
+	/* Read and buffer any input data from the client. */
+	if (FD_ISSET(connection_in, readset)) {
+		len = read(connection_in, buf, sizeof(buf));
+		if (len == 0) {
+			verbose("Connection closed by %.100s port %d",
+			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+			return -1;
+		} else if (len < 0) {
+			if (errno != EINTR && errno != EAGAIN &&
+			    errno != EWOULDBLOCK) {
+				verbose("Read error from remote host "
+				    "%.100s port %d: %.100s",
+				    ssh_remote_ipaddr(ssh),
+				    ssh_remote_port(ssh), strerror(errno));
+				cleanup_exit(255);
+			}
+		} else {
+			/* Buffer any received data. */
+			packet_process_incoming(buf, len);
+		}
+	}
+	return 0;
+}
+
+/*
+ * Sends data from internal buffers to client program stdin.
+ */
+static void
+process_output(fd_set *writeset, int connection_out)
+{
+	/* Send any buffered packet data to the client. */
+	if (FD_ISSET(connection_out, writeset))
+		packet_write_poll();
+}
+
+static void
+process_buffered_input_packets(struct ssh *ssh)
+{
+	ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL);
+}
+
+static void
+collect_children(struct ssh *ssh)
+{
+	pid_t pid;
+	sigset_t oset, nset;
+	int status;
+
+	/* block SIGCHLD while we check for dead children */
+	sigemptyset(&nset);
+	sigaddset(&nset, SIGCHLD);
+	sigprocmask(SIG_BLOCK, &nset, &oset);
+	if (child_terminated) {
+		debug("Received SIGCHLD.");
+		while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
+		    (pid < 0 && errno == EINTR))
+			if (pid > 0)
+				session_close_by_pid(ssh, pid, status);
+		child_terminated = 0;
+	}
+	sigprocmask(SIG_SETMASK, &oset, NULL);
+}
+
+void
+server_loop2(struct ssh *ssh, Authctxt *authctxt)
+{
+	fd_set *readset = NULL, *writeset = NULL;
+	int max_fd;
+	u_int nalloc = 0, connection_in, connection_out;
+	u_int64_t rekey_timeout_ms = 0;
+
+	debug("Entering interactive session for SSH2.");
+
+	signal(SIGCHLD, sigchld_handler);
+	child_terminated = 0;
+	connection_in = packet_get_connection_in();
+	connection_out = packet_get_connection_out();
+
+	if (!use_privsep) {
+		signal(SIGTERM, sigterm_handler);
+		signal(SIGINT, sigterm_handler);
+		signal(SIGQUIT, sigterm_handler);
+	}
+
+	notify_setup();
+
+	max_fd = MAXIMUM(connection_in, connection_out);
+	max_fd = MAXIMUM(max_fd, notify_pipe[0]);
+
+	server_init_dispatch();
+
+	for (;;) {
+		process_buffered_input_packets(ssh);
+
+		if (!ssh_packet_is_rekeying(ssh) &&
+		    packet_not_very_much_data_to_write())
+			channel_output_poll(ssh);
+		if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh))
+			rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
+		else
+			rekey_timeout_ms = 0;
+
+		wait_until_can_do_something(ssh, connection_in, connection_out,
+		    &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms);
+
+		if (received_sigterm) {
+			logit("Exiting on signal %d", (int)received_sigterm);
+			/* Clean up sessions, utmp, etc. */
+			cleanup_exit(255);
+		}
+
+		collect_children(ssh);
+		if (!ssh_packet_is_rekeying(ssh))
+			channel_after_select(ssh, readset, writeset);
+		if (process_input(ssh, readset, connection_in) < 0)
+			break;
+		process_output(writeset, connection_out);
+	}
+	collect_children(ssh);
+
+	free(readset);
+	free(writeset);
+
+	/* free all channels, no more reads and writes */
+	channel_free_all(ssh);
+
+	/* free remaining sessions, e.g. remove wtmp entries */
+	session_destroy_all(ssh, NULL);
+}
+
+static int
+server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh)
+{
+	debug("Got %d/%u for keepalive", type, seq);
+	/*
+	 * reset timeout, since we got a sane answer from the client.
+	 * even if this was generated by something other than
+	 * the bogus CHANNEL_REQUEST we send for keepalives.
+	 */
+	packet_set_alive_timeouts(0);
+	return 0;
+}
+
+static Channel *
+server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg)
+{
+	Channel *c = NULL;
+	char *target, *originator;
+	u_short target_port, originator_port;
+
+	target = packet_get_string(NULL);
+	target_port = packet_get_int();
+	originator = packet_get_string(NULL);
+	originator_port = packet_get_int();
+	packet_check_eom();
+
+	debug("%s: originator %s port %d, target %s port %d", __func__,
+	    originator, originator_port, target, target_port);
+
+	/* XXX fine grained permissions */
+	if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
+	    auth_opts->permit_port_forwarding_flag &&
+	    !options.disable_forwarding) {
+		c = channel_connect_to_port(ssh, target, target_port,
+		    "direct-tcpip", "direct-tcpip", reason, errmsg);
+	} else {
+		logit("refused local port forward: "
+		    "originator %s port %d, target %s port %d",
+		    originator, originator_port, target, target_port);
+		if (reason != NULL)
+			*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+	}
+
+	free(originator);
+	free(target);
+
+	return c;
+}
+
+static Channel *
+server_request_direct_streamlocal(struct ssh *ssh)
+{
+	Channel *c = NULL;
+	char *target, *originator;
+	u_short originator_port;
+	struct passwd *pw = the_authctxt->pw;
+
+	if (pw == NULL || !the_authctxt->valid)
+		fatal("%s: no/invalid user", __func__);
+
+	target = packet_get_string(NULL);
+	originator = packet_get_string(NULL);
+	originator_port = packet_get_int();
+	packet_check_eom();
+
+	debug("%s: originator %s port %d, target %s", __func__,
+	    originator, originator_port, target);
+
+	/* XXX fine grained permissions */
+	if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
+	    auth_opts->permit_port_forwarding_flag &&
+	    !options.disable_forwarding && (pw->pw_uid == 0 || use_privsep)) {
+		c = channel_connect_to_path(ssh, target,
+		    "direct-streamlocal@openssh.com", "direct-streamlocal");
+	} else {
+		logit("refused streamlocal port forward: "
+		    "originator %s port %d, target %s",
+		    originator, originator_port, target);
+	}
+
+	free(originator);
+	free(target);
+
+	return c;
+}
+
+static Channel *
+server_request_tun(struct ssh *ssh)
+{
+	Channel *c = NULL;
+	int mode, tun, sock;
+	char *tmp, *ifname = NULL;
+
+	mode = packet_get_int();
+	switch (mode) {
+	case SSH_TUNMODE_POINTOPOINT:
+	case SSH_TUNMODE_ETHERNET:
+		break;
+	default:
+		packet_send_debug("Unsupported tunnel device mode.");
+		return NULL;
+	}
+	if ((options.permit_tun & mode) == 0) {
+		packet_send_debug("Server has rejected tunnel device "
+		    "forwarding");
+		return NULL;
+	}
+
+	tun = packet_get_int();
+	if (auth_opts->force_tun_device != -1) {
+		if (tun != SSH_TUNID_ANY && auth_opts->force_tun_device != tun)
+			goto done;
+		tun = auth_opts->force_tun_device;
+	}
+	sock = tun_open(tun, mode, &ifname);
+	if (sock < 0)
+		goto done;
+	debug("Tunnel forwarding using interface %s", ifname);
+
+	c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1,
+	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
+	c->datagram = 1;
+#if defined(SSH_TUN_FILTER)
+	if (mode == SSH_TUNMODE_POINTOPOINT)
+		channel_register_filter(ssh, c->self, sys_tun_infilter,
+		    sys_tun_outfilter, NULL, NULL);
+#endif
+
+	/*
+	 * Update the list of names exposed to the session
+	 * XXX remove these if the tunnels are closed (won't matter
+	 * much if they are already in the environment though)
+	 */
+	tmp = tun_fwd_ifnames;
+	xasprintf(&tun_fwd_ifnames, "%s%s%s",
+	    tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames,
+	    tun_fwd_ifnames == NULL ? "" : ",",
+	    ifname);
+	free(tmp);
+	free(ifname);
+
+ done:
+	if (c == NULL)
+		packet_send_debug("Failed to open the tunnel device.");
+	return c;
+}
+
+static Channel *
+server_request_session(struct ssh *ssh)
+{
+	Channel *c;
+
+	debug("input_session_request");
+	packet_check_eom();
+
+	if (no_more_sessions) {
+		packet_disconnect("Possible attack: attempt to open a session "
+		    "after additional sessions disabled");
+	}
+
+	/*
+	 * A server session has no fd to read or write until a
+	 * CHANNEL_REQUEST for a shell is made, so we set the type to
+	 * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
+	 * CHANNEL_REQUEST messages is registered.
+	 */
+	c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL,
+	    -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
+	    0, "server-session", 1);
+	if (session_open(the_authctxt, c->self) != 1) {
+		debug("session open failed, free channel %d", c->self);
+		channel_free(ssh, c);
+		return NULL;
+	}
+	channel_register_cleanup(ssh, c->self, session_close_by_channel, 0);
+	return c;
+}
+
+static int
+server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
+{
+	Channel *c = NULL;
+	char *ctype;
+	const char *errmsg = NULL;
+	int rchan, reason = SSH2_OPEN_CONNECT_FAILED;
+	u_int rmaxpack, rwindow, len;
+
+	ctype = packet_get_string(&len);
+	rchan = packet_get_int();
+	rwindow = packet_get_int();
+	rmaxpack = packet_get_int();
+
+	debug("%s: ctype %s rchan %d win %d max %d", __func__,
+	    ctype, rchan, rwindow, rmaxpack);
+
+	if (strcmp(ctype, "session") == 0) {
+		c = server_request_session(ssh);
+	} else if (strcmp(ctype, "direct-tcpip") == 0) {
+		c = server_request_direct_tcpip(ssh, &reason, &errmsg);
+	} else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
+		c = server_request_direct_streamlocal(ssh);
+	} else if (strcmp(ctype, "tun@openssh.com") == 0) {
+		c = server_request_tun(ssh);
+	}
+	if (c != NULL) {
+		debug("%s: confirm %s", __func__, ctype);
+		c->remote_id = rchan;
+		c->have_remote_id = 1;
+		c->remote_window = rwindow;
+		c->remote_maxpacket = rmaxpack;
+		if (c->type != SSH_CHANNEL_CONNECTING) {
+			packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
+			packet_put_int(c->remote_id);
+			packet_put_int(c->self);
+			packet_put_int(c->local_window);
+			packet_put_int(c->local_maxpacket);
+			packet_send();
+		}
+	} else {
+		debug("%s: failure %s", __func__, ctype);
+		packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
+		packet_put_int(rchan);
+		packet_put_int(reason);
+		packet_put_cstring(errmsg ? errmsg : "open failed");
+		packet_put_cstring("");
+		packet_send();
+	}
+	free(ctype);
+	return 0;
+}
+
+static int
+server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp)
+{
+	struct sshbuf *resp = NULL;
+	struct sshbuf *sigbuf = NULL;
+	struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
+	int r, ndx, kexsigtype, use_kexsigtype, success = 0;
+	const u_char *blob;
+	u_char *sig = 0;
+	size_t blen, slen;
+
+	if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new", __func__);
+
+	kexsigtype = sshkey_type_plain(
+	    sshkey_type_from_name(ssh->kex->hostkey_alg));
+	while (ssh_packet_remaining(ssh) > 0) {
+		sshkey_free(key);
+		key = NULL;
+		if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
+		    (r = sshkey_from_blob(blob, blen, &key)) != 0) {
+			error("%s: couldn't parse key: %s",
+			    __func__, ssh_err(r));
+			goto out;
+		}
+		/*
+		 * Better check that this is actually one of our hostkeys
+		 * before attempting to sign anything with it.
+		 */
+		if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
+			error("%s: unknown host %s key",
+			    __func__, sshkey_type(key));
+			goto out;
+		}
+		/*
+		 * XXX refactor: make kex->sign just use an index rather
+		 * than passing in public and private keys
+		 */
+		if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
+		    (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
+			error("%s: can't retrieve hostkey %d", __func__, ndx);
+			goto out;
+		}
+		sshbuf_reset(sigbuf);
+		free(sig);
+		sig = NULL;
+		/*
+		 * For RSA keys, prefer to use the signature type negotiated
+		 * during KEX to the default (SHA1).
+		 */
+		use_kexsigtype = kexsigtype == KEY_RSA &&
+		    sshkey_type_plain(key->type) == KEY_RSA;
+		if ((r = sshbuf_put_cstring(sigbuf,
+		    "hostkeys-prove-00@openssh.com")) != 0 ||
+		    (r = sshbuf_put_string(sigbuf,
+		    ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
+		    (r = sshkey_puts(key, sigbuf)) != 0 ||
+		    (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
+		    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf),
+		    use_kexsigtype ? ssh->kex->hostkey_alg : NULL, 0)) != 0 ||
+		    (r = sshbuf_put_string(resp, sig, slen)) != 0) {
+			error("%s: couldn't prepare signature: %s",
+			    __func__, ssh_err(r));
+			goto out;
+		}
+	}
+	/* Success */
+	*respp = resp;
+	resp = NULL; /* don't free it */
+	success = 1;
+ out:
+	free(sig);
+	sshbuf_free(resp);
+	sshbuf_free(sigbuf);
+	sshkey_free(key);
+	return success;
+}
+
+static int
+server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
+{
+	char *rtype;
+	int want_reply;
+	int r, success = 0, allocated_listen_port = 0;
+	struct sshbuf *resp = NULL;
+	struct passwd *pw = the_authctxt->pw;
+
+	if (pw == NULL || !the_authctxt->valid)
+		fatal("%s: no/invalid user", __func__);
+
+	rtype = packet_get_string(NULL);
+	want_reply = packet_get_char();
+	debug("%s: rtype %s want_reply %d", __func__, rtype, want_reply);
+
+	/* -R style forwarding */
+	if (strcmp(rtype, "tcpip-forward") == 0) {
+		struct Forward fwd;
+
+		memset(&fwd, 0, sizeof(fwd));
+		fwd.listen_host = packet_get_string(NULL);
+		fwd.listen_port = (u_short)packet_get_int();
+		debug("%s: tcpip-forward listen %s port %d", __func__,
+		    fwd.listen_host, fwd.listen_port);
+
+		/* check permissions */
+		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
+		    !auth_opts->permit_port_forwarding_flag ||
+		    options.disable_forwarding ||
+		    (!want_reply && fwd.listen_port == 0) ||
+		    (fwd.listen_port != 0 &&
+		     !bind_permitted(fwd.listen_port, pw->pw_uid))) {
+			success = 0;
+			packet_send_debug("Server has disabled port forwarding.");
+		} else {
+			/* Start listening on the port */
+			success = channel_setup_remote_fwd_listener(ssh, &fwd,
+			    &allocated_listen_port, &options.fwd_opts);
+		}
+		free(fwd.listen_host);
+		if ((resp = sshbuf_new()) == NULL)
+			fatal("%s: sshbuf_new", __func__);
+		if (allocated_listen_port != 0 &&
+		    (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
+			fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
+	} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
+		struct Forward fwd;
+
+		memset(&fwd, 0, sizeof(fwd));
+		fwd.listen_host = packet_get_string(NULL);
+		fwd.listen_port = (u_short)packet_get_int();
+		debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
+		    fwd.listen_host, fwd.listen_port);
+
+		success = channel_cancel_rport_listener(ssh, &fwd);
+		free(fwd.listen_host);
+	} else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
+		struct Forward fwd;
+
+		memset(&fwd, 0, sizeof(fwd));
+		fwd.listen_path = packet_get_string(NULL);
+		debug("%s: streamlocal-forward listen path %s", __func__,
+		    fwd.listen_path);
+
+		/* check permissions */
+		if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
+		    || !auth_opts->permit_port_forwarding_flag ||
+		    options.disable_forwarding ||
+		    (pw->pw_uid != 0 && !use_privsep)) {
+			success = 0;
+			packet_send_debug("Server has disabled "
+			    "streamlocal forwarding.");
+		} else {
+			/* Start listening on the socket */
+			success = channel_setup_remote_fwd_listener(ssh,
+			    &fwd, NULL, &options.fwd_opts);
+		}
+		free(fwd.listen_path);
+	} else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
+		struct Forward fwd;
+
+		memset(&fwd, 0, sizeof(fwd));
+		fwd.listen_path = packet_get_string(NULL);
+		debug("%s: cancel-streamlocal-forward path %s", __func__,
+		    fwd.listen_path);
+
+		success = channel_cancel_rport_listener(ssh, &fwd);
+		free(fwd.listen_path);
+	} else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
+		no_more_sessions = 1;
+		success = 1;
+	} else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
+		success = server_input_hostkeys_prove(ssh, &resp);
+	}
+	if (want_reply) {
+		packet_start(success ?
+		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
+		if (success && resp != NULL)
+			ssh_packet_put_raw(ssh, sshbuf_ptr(resp),
+			    sshbuf_len(resp));
+		packet_send();
+		packet_write_wait();
+	}
+	free(rtype);
+	sshbuf_free(resp);
+	return 0;
+}
+
+static int
+server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
+{
+	Channel *c;
+	int id, reply, success = 0;
+	char *rtype;
+
+	id = packet_get_int();
+	rtype = packet_get_string(NULL);
+	reply = packet_get_char();
+
+	debug("server_input_channel_req: channel %d request %s reply %d",
+	    id, rtype, reply);
+
+	if ((c = channel_lookup(ssh, id)) == NULL)
+		packet_disconnect("server_input_channel_req: "
+		    "unknown channel %d", id);
+	if (!strcmp(rtype, "eow@openssh.com")) {
+		packet_check_eom();
+		chan_rcvd_eow(ssh, c);
+	} else if ((c->type == SSH_CHANNEL_LARVAL ||
+	    c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
+		success = session_input_channel_req(ssh, c, rtype);
+	if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
+		if (!c->have_remote_id)
+			fatal("%s: channel %d: no remote_id",
+			    __func__, c->self);
+		packet_start(success ?
+		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
+		packet_put_int(c->remote_id);
+		packet_send();
+	}
+	free(rtype);
+	return 0;
+}
+
+static void
+server_init_dispatch(void)
+{
+	debug("server_init_dispatch");
+	dispatch_init(&dispatch_protocol_error);
+	dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
+	dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
+	dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
+	dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
+	dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
+	dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
+	dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
+	dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
+	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
+	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
+	/* client_alive */
+	dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
+	dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
+	dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
+	dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
+	/* rekeying */
+	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
+}