Return to serverloop.c CVS log

Up to [local] / src / usr.bin / ssh

Remove uid checks from low port binds.  Now that ssh cannot be
setuid and sshd always has privsep on, we can remove the uid checks
for low port binds and just let the system do the check. We leave
a sanity check for the !privsep case so long as the code is stil
there.  with & ok djm@

/* $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 <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/queue.h>

#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 "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) {
				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;

	/*
	 * 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);
}