Adding upstream version 1:9.2p1.upstream/1%9.2p1upstream

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

1 files changed, 935 insertions, 0 deletions

diff --git a/serverloop.c b/serverloop.c
new file mode 100644
index 0000000..6db0916
--- /dev/null
+++ b/serverloop.c
@@ -0,0 +1,935 @@
+/* $OpenBSD: serverloop.c,v 1.234 2023/01/17 09:44:48 djm 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 <limits.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
+#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. */
+
+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(struct ssh *);
+
+/* 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;
+}
+
+/*ARGSUSED*/
+static void
+sigchld_handler(int sig)
+{
+	child_terminated = 1;
+}
+
+/*ARGSUSED*/
+static void
+sigterm_handler(int sig)
+{
+	received_sigterm = sig;
+}
+
+static void
+client_alive_check(struct ssh *ssh)
+{
+	char remote_id[512];
+	int r, channel_id;
+
+	/* timeout, check to see how many we have had */
+	if (options.client_alive_count_max > 0 &&
+	    ssh_packet_inc_alive_timeouts(ssh) >
+	    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) {
+		if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com"))
+		    != 0 ||
+		    (r = sshpkt_put_u8(ssh, 1)) != 0) /* boolean: want reply */
+			fatal_fr(r, "compose");
+	} else {
+		channel_request_start(ssh, channel_id,
+		    "keepalive@openssh.com", 1);
+	}
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal_fr(r, "send");
+}
+
+/*
+ * Sleep in ppoll() until we can do something.
+ * 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, struct pollfd **pfdp,
+    u_int *npfd_allocp, u_int *npfd_activep, sigset_t *sigsetp,
+    int *conn_in_readyp, int *conn_out_readyp)
+{
+	struct timespec timeout;
+	char remote_id[512];
+	int ret;
+	int client_alive_scheduled = 0;
+	u_int p;
+	time_t now;
+	static time_t last_client_time, unused_connection_expiry;
+
+	*conn_in_readyp = *conn_out_readyp = 0;
+
+	/* Prepare channel poll. First two pollfd entries are reserved */
+	ptimeout_init(&timeout);
+	channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout);
+	now = monotime();
+	if (*npfd_activep < 2)
+		fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */
+	if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) {
+		ptimeout_deadline_sec(&timeout,
+		    ssh_packet_get_rekey_timeout(ssh));
+	}
+
+	/*
+	 * If no channels are open and UnusedConnectionTimeout is set, then
+	 * start the clock to terminate the connection.
+	 */
+	if (options.unused_connection_timeout != 0) {
+		if (channel_still_open(ssh) || unused_connection_expiry == 0) {
+			unused_connection_expiry = now +
+			    options.unused_connection_timeout;
+		}
+		ptimeout_deadline_monotime(&timeout, unused_connection_expiry);
+	}
+
+	/*
+	 * 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) {
+		/* Time we last heard from the client OR sent a keepalive */
+		if (last_client_time == 0)
+			last_client_time = now;
+		ptimeout_deadline_sec(&timeout, options.client_alive_interval);
+		/* XXX ? deadline_monotime(last_client_time + alive_interval) */
+		client_alive_scheduled = 1;
+	}
+
+#if 0
+	/* wrong: bad condition XXX */
+	if (channel_not_very_much_buffered_data())
+#endif
+	/* Monitor client connection on reserved pollfd entries */
+	(*pfdp)[0].fd = connection_in;
+	(*pfdp)[0].events = POLLIN;
+	(*pfdp)[1].fd = connection_out;
+	(*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0;
+
+	/*
+	 * 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 && ssh_packet_not_very_much_data_to_write(ssh))
+		ptimeout_deadline_ms(&timeout, 100);
+
+	/* Wait for something to happen, or the timeout to expire. */
+	ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp);
+
+	if (ret == -1) {
+		for (p = 0; p < *npfd_activep; p++)
+			(*pfdp)[p].revents = 0;
+		if (errno != EINTR)
+			fatal_f("ppoll: %.100s", strerror(errno));
+		return;
+	}
+
+	*conn_in_readyp = (*pfdp)[0].revents != 0;
+	*conn_out_readyp = (*pfdp)[1].revents != 0;
+
+	now = monotime(); /* need to reset after ppoll() */
+	/* ClientAliveInterval probing */
+	if (client_alive_scheduled) {
+		if (ret == 0 &&
+		    now > last_client_time + options.client_alive_interval) {
+			/* ppoll timed out and we're due to probe */
+			client_alive_check(ssh);
+			last_client_time = now;
+		} else if (ret != 0 && *conn_in_readyp) {
+			/* Data from peer; reset probe timer. */
+			last_client_time = now;
+		}
+	}
+
+	/* UnusedConnectionTimeout handling */
+	if (unused_connection_expiry != 0 &&
+	    now > unused_connection_expiry && !channel_still_open(ssh)) {
+		sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
+		logit("terminating inactive connection from %s", remote_id);
+		cleanup_exit(255);
+	}
+}
+
+/*
+ * Processes input from the client and the program.  Input data is stored
+ * in buffers and processed later.
+ */
+static int
+process_input(struct ssh *ssh, int connection_in)
+{
+	int r;
+
+	if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
+		return 0; /* success */
+	if (r == SSH_ERR_SYSTEM_ERROR) {
+		if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
+			return 0;
+		if (errno == EPIPE) {
+			verbose("Connection closed by %.100s port %d",
+			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+			return -1;
+		}
+		verbose("Read error from remote host %s port %d: %s",
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+		    strerror(errno));
+		cleanup_exit(255);
+	}
+	return -1;
+}
+
+/*
+ * Sends data from internal buffers to client program stdin.
+ */
+static void
+process_output(struct ssh *ssh, int connection_out)
+{
+	int r;
+
+	/* Send any buffered packet data to the client. */
+	if ((r = ssh_packet_write_poll(ssh)) != 0) {
+		sshpkt_fatal(ssh, r, "%s: ssh_packet_write_poll",
+		    __func__);
+	}
+}
+
+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;
+	int status;
+
+	if (child_terminated) {
+		debug("Received SIGCHLD.");
+		while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
+		    (pid == -1 && errno == EINTR))
+			if (pid > 0)
+				session_close_by_pid(ssh, pid, status);
+		child_terminated = 0;
+	}
+}
+
+void
+server_loop2(struct ssh *ssh, Authctxt *authctxt)
+{
+	struct pollfd *pfd = NULL;
+	u_int npfd_alloc = 0, npfd_active = 0;
+	int r, conn_in_ready, conn_out_ready;
+	u_int connection_in, connection_out;
+	sigset_t bsigset, osigset;
+
+	debug("Entering interactive session for SSH2.");
+
+	if (sigemptyset(&bsigset) == -1 || sigaddset(&bsigset, SIGCHLD) == -1)
+		error_f("bsigset setup: %s", strerror(errno));
+	ssh_signal(SIGCHLD, sigchld_handler);
+	child_terminated = 0;
+	connection_in = ssh_packet_get_connection_in(ssh);
+	connection_out = ssh_packet_get_connection_out(ssh);
+
+	if (!use_privsep) {
+		ssh_signal(SIGTERM, sigterm_handler);
+		ssh_signal(SIGINT, sigterm_handler);
+		ssh_signal(SIGQUIT, sigterm_handler);
+	}
+
+	server_init_dispatch(ssh);
+
+	for (;;) {
+		process_buffered_input_packets(ssh);
+
+		if (!ssh_packet_is_rekeying(ssh) &&
+		    ssh_packet_not_very_much_data_to_write(ssh))
+			channel_output_poll(ssh);
+
+		/*
+		 * Block SIGCHLD while we check for dead children, then pass
+		 * the old signal mask through to ppoll() so that it'll wake
+		 * up immediately if a child exits after we've called waitpid().
+		 */
+		if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1)
+			error_f("bsigset sigprocmask: %s", strerror(errno));
+		collect_children(ssh);
+		wait_until_can_do_something(ssh, connection_in, connection_out,
+		    &pfd, &npfd_alloc, &npfd_active, &osigset,
+		    &conn_in_ready, &conn_out_ready);
+		if (sigprocmask(SIG_UNBLOCK, &bsigset, &osigset) == -1)
+			error_f("osigset sigprocmask: %s", strerror(errno));
+
+		if (received_sigterm) {
+			logit("Exiting on signal %d", (int)received_sigterm);
+			/* Clean up sessions, utmp, etc. */
+			cleanup_exit(255);
+		}
+
+		channel_after_poll(ssh, pfd, npfd_active);
+		if (conn_in_ready &&
+		    process_input(ssh, connection_in) < 0)
+			break;
+		/* A timeout may have triggered rekeying */
+		if ((r = ssh_packet_check_rekey(ssh)) != 0)
+			fatal_fr(r, "cannot start rekeying");
+		if (conn_out_ready)
+			process_output(ssh, connection_out);
+	}
+	collect_children(ssh);
+	free(pfd);
+
+	/* 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.
+	 */
+	ssh_packet_set_alive_timeouts(ssh, 0);
+	return 0;
+}
+
+static Channel *
+server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg)
+{
+	Channel *c = NULL;
+	char *target = NULL, *originator = NULL;
+	u_int target_port = 0, originator_port = 0;
+	int r;
+
+	if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &target_port)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	if (target_port > 0xFFFF) {
+		error_f("invalid target port");
+		*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+		goto out;
+	}
+	if (originator_port > 0xFFFF) {
+		error_f("invalid originator port");
+		*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+		goto out;
+	}
+
+	debug_f("originator %s port %u, target %s port %u",
+	    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;
+	}
+
+ out:
+	free(originator);
+	free(target);
+	return c;
+}
+
+static Channel *
+server_request_direct_streamlocal(struct ssh *ssh)
+{
+	Channel *c = NULL;
+	char *target = NULL, *originator = NULL;
+	u_int originator_port = 0;
+	struct passwd *pw = the_authctxt->pw;
+	int r;
+
+	if (pw == NULL || !the_authctxt->valid)
+		fatal_f("no/invalid user");
+
+	if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	if (originator_port > 0xFFFF) {
+		error_f("invalid originator port");
+		goto out;
+	}
+
+	debug_f("originator %s port %d, target %s",
+	    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);
+	}
+
+out:
+	free(originator);
+	free(target);
+	return c;
+}
+
+static Channel *
+server_request_tun(struct ssh *ssh)
+{
+	Channel *c = NULL;
+	u_int mode, tun;
+	int r, sock;
+	char *tmp, *ifname = NULL;
+
+	if ((r = sshpkt_get_u32(ssh, &mode)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse mode", __func__);
+	switch (mode) {
+	case SSH_TUNMODE_POINTOPOINT:
+	case SSH_TUNMODE_ETHERNET:
+		break;
+	default:
+		ssh_packet_send_debug(ssh, "Unsupported tunnel device mode.");
+		return NULL;
+	}
+	if ((options.permit_tun & mode) == 0) {
+		ssh_packet_send_debug(ssh, "Server has rejected tunnel device "
+		    "forwarding");
+		return NULL;
+	}
+
+	if ((r = sshpkt_get_u32(ssh, &tun)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse device", __func__);
+	if (tun > INT_MAX) {
+		debug_f("invalid tun");
+		goto done;
+	}
+	if (auth_opts->force_tun_device != -1) {
+		if (tun != SSH_TUNID_ANY &&
+		    auth_opts->force_tun_device != (int)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)
+		ssh_packet_send_debug(ssh, "Failed to open the tunnel device.");
+	return c;
+}
+
+static Channel *
+server_request_session(struct ssh *ssh)
+{
+	Channel *c;
+	int r;
+
+	debug("input_session_request");
+	if ((r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	if (no_more_sessions) {
+		ssh_packet_disconnect(ssh, "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 = NULL;
+	const char *errmsg = NULL;
+	int r, reason = SSH2_OPEN_CONNECT_FAILED;
+	u_int rchan = 0, rmaxpack = 0, rwindow = 0;
+
+	if ((r = sshpkt_get_cstring(ssh, &ctype, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	debug_f("ctype %s rchan %u win %u max %u",
+	    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_f("confirm %s", ctype);
+		c->remote_id = rchan;
+		c->have_remote_id = 1;
+		c->remote_window = rwindow;
+		c->remote_maxpacket = rmaxpack;
+		if (c->type != SSH_CHANNEL_CONNECTING) {
+			if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+			    (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
+			    (r = sshpkt_send(ssh)) != 0) {
+				sshpkt_fatal(ssh, r,
+				    "%s: send open confirm", __func__);
+			}
+		}
+	} else {
+		debug_f("failure %s", ctype);
+		if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, reason)) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, errmsg ? errmsg : "open failed")) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0) {
+			sshpkt_fatal(ssh, r,
+			    "%s: send open failure", __func__);
+		}
+	}
+	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, success = 0;
+	const u_char *blob;
+	const char *sigalg, *kex_rsa_sigalg = NULL;
+	u_char *sig = 0;
+	size_t blen, slen;
+
+	if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new");
+	if (sshkey_type_plain(sshkey_type_from_name(
+	    ssh->kex->hostkey_alg)) == KEY_RSA)
+		kex_rsa_sigalg = 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_fr(r, "parse key");
+			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_f("unknown host %s key", 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_f("can't retrieve hostkey %d", 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).
+		 */
+		sigalg = NULL;
+		if (sshkey_type_plain(key->type) == KEY_RSA) {
+			if (kex_rsa_sigalg != NULL)
+				sigalg = kex_rsa_sigalg;
+			else if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED)
+				sigalg = "rsa-sha2-512";
+			else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
+				sigalg = "rsa-sha2-256";
+		}
+		debug3_f("sign %s key (index %d) using sigalg %s",
+		    sshkey_type(key), ndx, sigalg == NULL ? "default" : sigalg);
+		if ((r = sshbuf_put_cstring(sigbuf,
+		    "hostkeys-prove-00@openssh.com")) != 0 ||
+		    (r = sshbuf_put_stringb(sigbuf,
+		    ssh->kex->session_id)) != 0 ||
+		    (r = sshkey_puts(key, sigbuf)) != 0 ||
+		    (r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
+		    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), sigalg)) != 0 ||
+		    (r = sshbuf_put_string(resp, sig, slen)) != 0) {
+			error_fr(r, "assemble signature");
+			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 = NULL;
+	u_char want_reply = 0;
+	int r, success = 0, allocated_listen_port = 0;
+	u_int port = 0;
+	struct sshbuf *resp = NULL;
+	struct passwd *pw = the_authctxt->pw;
+	struct Forward fwd;
+
+	memset(&fwd, 0, sizeof(fwd));
+	if (pw == NULL || !the_authctxt->valid)
+		fatal_f("no/invalid user");
+
+	if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
+	    (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	debug_f("rtype %s want_reply %d", rtype, want_reply);
+
+	/* -R style forwarding */
+	if (strcmp(rtype, "tcpip-forward") == 0) {
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
+		    (r = sshpkt_get_u32(ssh, &port)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse tcpip-forward", __func__);
+		debug_f("tcpip-forward listen %s port %u",
+		    fwd.listen_host, port);
+		if (port <= INT_MAX)
+			fwd.listen_port = (int)port;
+		/* check permissions */
+		if (port > INT_MAX ||
+		    (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;
+			ssh_packet_send_debug(ssh, "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);
+		}
+		if ((resp = sshbuf_new()) == NULL)
+			fatal_f("sshbuf_new");
+		if (allocated_listen_port != 0 &&
+		    (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
+			fatal_fr(r, "sshbuf_put_u32");
+	} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
+		    (r = sshpkt_get_u32(ssh, &port)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse cancel-tcpip-forward", __func__);
+
+		debug_f("cancel-tcpip-forward addr %s port %d",
+		    fwd.listen_host, port);
+		if (port <= INT_MAX) {
+			fwd.listen_port = (int)port;
+			success = channel_cancel_rport_listener(ssh, &fwd);
+		}
+	} else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse streamlocal-forward@openssh.com", __func__);
+		debug_f("streamlocal-forward listen path %s",
+		    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;
+			ssh_packet_send_debug(ssh, "Server has disabled "
+			    "streamlocal forwarding.");
+		} else {
+			/* Start listening on the socket */
+			success = channel_setup_remote_fwd_listener(ssh,
+			    &fwd, NULL, &options.fwd_opts);
+		}
+	} else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
+		if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse cancel-streamlocal-forward@openssh.com", __func__);
+		debug_f("cancel-streamlocal-forward path %s",
+		    fwd.listen_path);
+
+		success = channel_cancel_rport_listener(ssh, &fwd);
+	} 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);
+	}
+	/* XXX sshpkt_get_end() */
+	if (want_reply) {
+		if ((r = sshpkt_start(ssh, success ?
+		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE)) != 0 ||
+		    (success && resp != NULL && (r = sshpkt_putb(ssh, resp)) != 0) ||
+		    (r = sshpkt_send(ssh)) != 0 ||
+		    (r = ssh_packet_write_wait(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: send reply", __func__);
+	}
+	free(fwd.listen_host);
+	free(fwd.listen_path);
+	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 r, success = 0;
+	char *rtype = NULL;
+	u_char want_reply = 0;
+	u_int id = 0;
+
+	if ((r = sshpkt_get_u32(ssh, &id)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
+	    (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	debug("server_input_channel_req: channel %u request %s reply %d",
+	    id, rtype, want_reply);
+
+	if (id >= INT_MAX || (c = channel_lookup(ssh, (int)id)) == NULL) {
+		ssh_packet_disconnect(ssh, "%s: unknown channel %d",
+		    __func__, id);
+	}
+	if (!strcmp(rtype, "eow@openssh.com")) {
+		if ((r = sshpkt_get_end(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+		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 (want_reply && !(c->flags & CHAN_CLOSE_SENT)) {
+		if (!c->have_remote_id)
+			fatal_f("channel %d: no remote_id", c->self);
+		if ((r = sshpkt_start(ssh, success ?
+		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: send reply", __func__);
+	}
+	free(rtype);
+	return 0;
+}
+
+static void
+server_init_dispatch(struct ssh *ssh)
+{
+	debug("server_init_dispatch");
+	ssh_dispatch_init(ssh, &dispatch_protocol_error);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
+	ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
+	/* client_alive */
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
+	ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
+	ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
+	ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
+	/* rekeying */
+	ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
+}