[openssh.git] / mux.c

/* $OpenBSD: mux.c,v 1.1 2008/05/09 14:18:44 djm Exp $ */
/*
 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* ssh session multiplexing support */

#include "includes.h"

#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <paths.h>

#ifdef HAVE_UTIL_H
# include <util.h>
#endif

#ifdef HAVE_LIBUTIL_H
# include <libutil.h>
#endif

#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "log.h"
#include "ssh.h"
#include "pathnames.h"
#include "misc.h"
#include "match.h"
#include "buffer.h"
#include "channels.h"
#include "msg.h"
#include "packet.h"
#include "monitor_fdpass.h"
#include "sshpty.h"
#include "key.h"
#include "readconf.h"
#include "clientloop.h"

/* from ssh.c */
extern int tty_flag;
extern Options options;
extern int stdin_null_flag;
extern char *host;
int subsystem_flag;
extern Buffer command;

/* fd to control socket */
int muxserver_sock = -1;

/* Multiplexing control command */
u_int muxclient_command = 0;

/* Set when signalled. */
static volatile sig_atomic_t muxclient_terminate = 0;

/* PID of multiplex server */
static u_int muxserver_pid = 0;


/* ** Multiplexing master support */

/* Prepare a mux master to listen on a Unix domain socket. */
void
muxserver_listen(void)
{
	struct sockaddr_un addr;
	mode_t old_umask;
	int addr_len;

	if (options.control_path == NULL ||
	    options.control_master == SSHCTL_MASTER_NO)
		return;

	debug("setting up multiplex master socket");

	memset(&addr, '\0', sizeof(addr));
	addr.sun_family = AF_UNIX;
	addr_len = offsetof(struct sockaddr_un, sun_path) +
	    strlen(options.control_path) + 1;

	if (strlcpy(addr.sun_path, options.control_path,
	    sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
		fatal("ControlPath too long");

	if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
		fatal("%s socket(): %s", __func__, strerror(errno));

	old_umask = umask(0177);
	if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) {
		muxserver_sock = -1;
		if (errno == EINVAL || errno == EADDRINUSE)
			fatal("ControlSocket %s already exists",
			    options.control_path);
		else
			fatal("%s bind(): %s", __func__, strerror(errno));
	}
	umask(old_umask);

	if (listen(muxserver_sock, 64) == -1)
		fatal("%s listen(): %s", __func__, strerror(errno));

	set_nonblock(muxserver_sock);
}

/* Callback on open confirmation in mux master for a mux client session. */
static void
client_extra_session2_setup(int id, void *arg)
{
	struct mux_session_confirm_ctx *cctx = arg;
	const char *display;
	Channel *c;
	int i;

	if (cctx == NULL)
		fatal("%s: cctx == NULL", __func__);
	if ((c = channel_lookup(id)) == NULL)
		fatal("%s: no channel for id %d", __func__, id);

	display = getenv("DISPLAY");
	if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
		char *proto, *data;
		/* Get reasonable local authentication information. */
		client_x11_get_proto(display, options.xauth_location,
		    options.forward_x11_trusted, &proto, &data);
		/* Request forwarding with authentication spoofing. */
		debug("Requesting X11 forwarding with authentication spoofing.");
		x11_request_forwarding_with_spoofing(id, display, proto, data);
		/* XXX wait for reply */
	}

	if (cctx->want_agent_fwd && options.forward_agent) {
		debug("Requesting authentication agent forwarding.");
		channel_request_start(id, "auth-agent-req@openssh.com", 0);
		packet_send();
	}

	client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
	    cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);

	c->open_confirm_ctx = NULL;
	buffer_free(&cctx->cmd);
	xfree(cctx->term);
	if (cctx->env != NULL) {
		for (i = 0; cctx->env[i] != NULL; i++)
			xfree(cctx->env[i]);
		xfree(cctx->env);
	}
	xfree(cctx);
}

/*
 * Accept a connection on the mux master socket and process the
 * client's request. Returns flag indicating whether mux master should
 * begin graceful close.
 */
int
muxserver_accept_control(void)
{
	Buffer m;
	Channel *c;
	int client_fd, new_fd[3], ver, allowed, window, packetmax;
	socklen_t addrlen;
	struct sockaddr_storage addr;
	struct mux_session_confirm_ctx *cctx;
	char *cmd;
	u_int i, j, len, env_len, mux_command, flags;
	uid_t euid;
	gid_t egid;
	int start_close = 0;

	/*
	 * Accept connection on control socket
	 */
	memset(&addr, 0, sizeof(addr));
	addrlen = sizeof(addr);
	if ((client_fd = accept(muxserver_sock,
	    (struct sockaddr*)&addr, &addrlen)) == -1) {
		error("%s accept: %s", __func__, strerror(errno));
		return 0;
	}

	if (getpeereid(client_fd, &euid, &egid) < 0) {
		error("%s getpeereid failed: %s", __func__, strerror(errno));
		close(client_fd);
		return 0;
	}
	if ((euid != 0) && (getuid() != euid)) {
		error("control mode uid mismatch: peer euid %u != uid %u",
		    (u_int) euid, (u_int) getuid());
		close(client_fd);
		return 0;
	}

	/* XXX handle asynchronously */
	unset_nonblock(client_fd);

	/* Read command */
	buffer_init(&m);
	if (ssh_msg_recv(client_fd, &m) == -1) {
		error("%s: client msg_recv failed", __func__);
		close(client_fd);
		buffer_free(&m);
		return 0;
	}
	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
		error("%s: wrong client version %d", __func__, ver);
		buffer_free(&m);
		close(client_fd);
		return 0;
	}

	allowed = 1;
	mux_command = buffer_get_int(&m);
	flags = buffer_get_int(&m);

	buffer_clear(&m);

	switch (mux_command) {
	case SSHMUX_COMMAND_OPEN:
		if (options.control_master == SSHCTL_MASTER_ASK ||
		    options.control_master == SSHCTL_MASTER_AUTO_ASK)
			allowed = ask_permission("Allow shared connection "
			    "to %s? ", host);
		/* continue below */
		break;
	case SSHMUX_COMMAND_TERMINATE:
		if (options.control_master == SSHCTL_MASTER_ASK ||
		    options.control_master == SSHCTL_MASTER_AUTO_ASK)
			allowed = ask_permission("Terminate shared connection "
			    "to %s? ", host);
		if (allowed)
			start_close = 1;
		/* FALLTHROUGH */
	case SSHMUX_COMMAND_ALIVE_CHECK:
		/* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */
		buffer_clear(&m);
		buffer_put_int(&m, allowed);
		buffer_put_int(&m, getpid());
		if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
			error("%s: client msg_send failed", __func__);
			close(client_fd);
			buffer_free(&m);
			return start_close;
		}
		buffer_free(&m);
		close(client_fd);
		return start_close;
	default:
		error("Unsupported command %d", mux_command);
		buffer_free(&m);
		close(client_fd);
		return 0;
	}

	/* Reply for SSHMUX_COMMAND_OPEN */
	buffer_clear(&m);
	buffer_put_int(&m, allowed);
	buffer_put_int(&m, getpid());
	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
		error("%s: client msg_send failed", __func__);
		close(client_fd);
		buffer_free(&m);
		return 0;
	}

	if (!allowed) {
		error("Refused control connection");
		close(client_fd);
		buffer_free(&m);
		return 0;
	}

	buffer_clear(&m);
	if (ssh_msg_recv(client_fd, &m) == -1) {
		error("%s: client msg_recv failed", __func__);
		close(client_fd);
		buffer_free(&m);
		return 0;
	}
	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
		error("%s: wrong client version %d", __func__, ver);
		buffer_free(&m);
		close(client_fd);
		return 0;
	}

	cctx = xcalloc(1, sizeof(*cctx));
	cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0;
	cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0;
	cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0;
	cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0;
	cctx->term = buffer_get_string(&m, &len);

	cmd = buffer_get_string(&m, &len);
	buffer_init(&cctx->cmd);
	buffer_append(&cctx->cmd, cmd, strlen(cmd));

	env_len = buffer_get_int(&m);
	env_len = MIN(env_len, 4096);
	debug3("%s: receiving %d env vars", __func__, env_len);
	if (env_len != 0) {
		cctx->env = xcalloc(env_len + 1, sizeof(*cctx->env));
		for (i = 0; i < env_len; i++)
			cctx->env[i] = buffer_get_string(&m, &len);
		cctx->env[i] = NULL;
	}

	debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__,
	    cctx->want_tty, cctx->want_subsys, cmd);
	xfree(cmd);

	/* Gather fds from client */
	for(i = 0; i < 3; i++) {
		if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) {
			error("%s: failed to receive fd %d from slave",
			    __func__, i);
			for (j = 0; j < i; j++)
				close(new_fd[j]);
			for (j = 0; j < env_len; j++)
				xfree(cctx->env[j]);
			if (env_len > 0)
				xfree(cctx->env);
			xfree(cctx->term);
			buffer_free(&cctx->cmd);
			close(client_fd);
			xfree(cctx);
			return 0;
		}
	}

	debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
	    new_fd[0], new_fd[1], new_fd[2]);

	/* Try to pick up ttymodes from client before it goes raw */
	if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
		error("%s: tcgetattr: %s", __func__, strerror(errno));

	/* This roundtrip is just for synchronisation of ttymodes */
	buffer_clear(&m);
	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
		error("%s: client msg_send failed", __func__);
		close(client_fd);
		close(new_fd[0]);
		close(new_fd[1]);
		close(new_fd[2]);
		buffer_free(&m);
		xfree(cctx->term);
		if (env_len != 0) {
			for (i = 0; i < env_len; i++)
				xfree(cctx->env[i]);
			xfree(cctx->env);
		}
		return 0;
	}
	buffer_free(&m);

	/* enable nonblocking unless tty */
	if (!isatty(new_fd[0]))
		set_nonblock(new_fd[0]);
	if (!isatty(new_fd[1]))
		set_nonblock(new_fd[1]);
	if (!isatty(new_fd[2]))
		set_nonblock(new_fd[2]);

	set_nonblock(client_fd);

	window = CHAN_SES_WINDOW_DEFAULT;
	packetmax = CHAN_SES_PACKET_DEFAULT;
	if (cctx->want_tty) {
		window >>= 1;
		packetmax >>= 1;
	}
	
	c = channel_new("session", SSH_CHANNEL_OPENING,
	    new_fd[0], new_fd[1], new_fd[2], window, packetmax,
	    CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);

	/* XXX */
	c->ctl_fd = client_fd;

	debug3("%s: channel_new: %d", __func__, c->self);

	channel_send_open(c->self);
	channel_register_open_confirm(c->self,
	    client_extra_session2_setup, cctx);
	return 0;
}

/* ** Multiplexing client support */

/* Exit signal handler */
static void
control_client_sighandler(int signo)
{
	muxclient_terminate = signo;
}

/*
 * Relay signal handler - used to pass some signals from mux client to
 * mux master.
 */
static void
control_client_sigrelay(int signo)
{
	int save_errno = errno;

	if (muxserver_pid > 1)
		kill(muxserver_pid, signo);

	errno = save_errno;
}

/* Check mux client environment variables before passing them to mux master. */
static int
env_permitted(char *env)
{
	int i, ret;
	char name[1024], *cp;

	if ((cp = strchr(env, '=')) == NULL || cp == env)
		return (0);
	ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
	if (ret <= 0 || (size_t)ret >= sizeof(name))
		fatal("env_permitted: name '%.100s...' too long", env);

	for (i = 0; i < options.num_send_env; i++)
		if (match_pattern(name, options.send_env[i]))
			return (1);

	return (0);
}

/* Multiplex client main loop. */
void
muxclient(const char *path)
{
	struct sockaddr_un addr;
	int i, r, fd, sock, exitval[2], num_env, addr_len;
	Buffer m;
	char *term;
	extern char **environ;
	u_int  flags;

	if (muxclient_command == 0)
		muxclient_command = SSHMUX_COMMAND_OPEN;

	switch (options.control_master) {
	case SSHCTL_MASTER_AUTO:
	case SSHCTL_MASTER_AUTO_ASK:
		debug("auto-mux: Trying existing master");
		/* FALLTHROUGH */
	case SSHCTL_MASTER_NO:
		break;
	default:
		return;
	}

	memset(&addr, '\0', sizeof(addr));
	addr.sun_family = AF_UNIX;
	addr_len = offsetof(struct sockaddr_un, sun_path) +
	    strlen(path) + 1;

	if (strlcpy(addr.sun_path, path,
	    sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
		fatal("ControlPath too long");

	if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
		fatal("%s socket(): %s", __func__, strerror(errno));

	if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
		if (muxclient_command != SSHMUX_COMMAND_OPEN) {
			fatal("Control socket connect(%.100s): %s", path,
			    strerror(errno));
		}
		if (errno == ENOENT)
			debug("Control socket \"%.100s\" does not exist", path);
		else {
			error("Control socket connect(%.100s): %s", path,
			    strerror(errno));
		}
		close(sock);
		return;
	}

	if (stdin_null_flag) {
		if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
			fatal("open(/dev/null): %s", strerror(errno));
		if (dup2(fd, STDIN_FILENO) == -1)
			fatal("dup2: %s", strerror(errno));
		if (fd > STDERR_FILENO)
			close(fd);
	}

	term = getenv("TERM");

	flags = 0;
	if (tty_flag)
		flags |= SSHMUX_FLAG_TTY;
	if (subsystem_flag)
		flags |= SSHMUX_FLAG_SUBSYS;
	if (options.forward_x11)
		flags |= SSHMUX_FLAG_X11_FWD;
	if (options.forward_agent)
		flags |= SSHMUX_FLAG_AGENT_FWD;

	signal(SIGPIPE, SIG_IGN);

	buffer_init(&m);

	/* Send our command to server */
	buffer_put_int(&m, muxclient_command);
	buffer_put_int(&m, flags);
	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
		fatal("%s: msg_send", __func__);
	buffer_clear(&m);

	/* Get authorisation status and PID of controlee */
	if (ssh_msg_recv(sock, &m) == -1)
		fatal("%s: msg_recv", __func__);
	if (buffer_get_char(&m) != SSHMUX_VER)
		fatal("%s: wrong version", __func__);
	if (buffer_get_int(&m) != 1)
		fatal("Connection to master denied");
	muxserver_pid = buffer_get_int(&m);

	buffer_clear(&m);

	switch (muxclient_command) {
	case SSHMUX_COMMAND_ALIVE_CHECK:
		fprintf(stderr, "Master running (pid=%d)\r\n",
		    muxserver_pid);
		exit(0);
	case SSHMUX_COMMAND_TERMINATE:
		fprintf(stderr, "Exit request sent.\r\n");
		exit(0);
	case SSHMUX_COMMAND_OPEN:
		/* continue below */
		break;
	default:
		fatal("silly muxclient_command %d", muxclient_command);
	}

	/* SSHMUX_COMMAND_OPEN */
	buffer_put_cstring(&m, term ? term : "");
	buffer_append(&command, "\0", 1);
	buffer_put_cstring(&m, buffer_ptr(&command));

	if (options.num_send_env == 0 || environ == NULL) {
		buffer_put_int(&m, 0);
	} else {
		/* Pass environment */
		num_env = 0;
		for (i = 0; environ[i] != NULL; i++)
			if (env_permitted(environ[i]))
				num_env++; /* Count */

		buffer_put_int(&m, num_env);

		for (i = 0; environ[i] != NULL && num_env >= 0; i++)
			if (env_permitted(environ[i])) {
				num_env--;
				buffer_put_cstring(&m, environ[i]);
			}
	}

	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
		fatal("%s: msg_send", __func__);

	if (mm_send_fd(sock, STDIN_FILENO) == -1 ||
	    mm_send_fd(sock, STDOUT_FILENO) == -1 ||
	    mm_send_fd(sock, STDERR_FILENO) == -1)
		fatal("%s: send fds failed", __func__);

	/* Wait for reply, so master has a chance to gather ttymodes */
	buffer_clear(&m);
	if (ssh_msg_recv(sock, &m) == -1)
		fatal("%s: msg_recv", __func__);
	if (buffer_get_char(&m) != SSHMUX_VER)
		fatal("%s: wrong version", __func__);
	buffer_free(&m);

	signal(SIGHUP, control_client_sighandler);
	signal(SIGINT, control_client_sighandler);
	signal(SIGTERM, control_client_sighandler);
	signal(SIGWINCH, control_client_sigrelay);

	if (tty_flag)
		enter_raw_mode();

	/*
	 * Stick around until the controlee closes the client_fd.
	 * Before it does, it is expected to write this process' exit
	 * value (one int). This process must read the value and wait for
	 * the closure of the client_fd; if this one closes early, the 
	 * multiplex master will terminate early too (possibly losing data).
	 */
	exitval[0] = 0;
	for (i = 0; !muxclient_terminate && i < (int)sizeof(exitval);) {
		r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
		if (r == 0) {
			debug2("Received EOF from master");
			break;
		}
		if (r == -1) {
			if (errno == EINTR)
				continue;
			fatal("%s: read %s", __func__, strerror(errno));
		}
		i += r;
	}

	close(sock);
	leave_raw_mode();
	if (i > (int)sizeof(int))
		fatal("%s: master returned too much data (%d > %lu)",
		    __func__, i, sizeof(int));
	if (muxclient_terminate) {
		debug2("Exiting on signal %d", muxclient_terminate);
		exitval[0] = 255;
	} else if (i < (int)sizeof(int)) {
		debug2("Control master terminated unexpectedly");
		exitval[0] = 255;
	} else
		debug2("Received exit status from master %d", exitval[0]);

	if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
		fprintf(stderr, "Shared connection to %s closed.\r\n", host);

	exit(exitval[0]);
}
Commit	Line	Data
3bcced4c	1	/* $OpenBSD: mux.c,v 1.1 2008/05/09 14:18:44 djm Exp $ */
	2	/*
	3	* Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
	4	*
	5	* Permission to use, copy, modify, and distribute this software for any
	6	* purpose with or without fee is hereby granted, provided that the above
	7	* copyright notice and this permission notice appear in all copies.
	8	*
	9	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	10	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	11	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	12	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	13	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	14	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	15	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	16	*/
	17
	18	/* ssh session multiplexing support */
	19
b3ef88dc	20	#include "includes.h"
b3ef88dc	21
3bcced4c	22	#include <sys/types.h>
	23	#include <sys/param.h>
	24	#include <sys/stat.h>
	25	#include <sys/socket.h>
	26	#include <sys/un.h>
	27
	28	#include <errno.h>
	29	#include <fcntl.h>
	30	#include <signal.h>
	31	#include <stdarg.h>
	32	#include <stddef.h>
	33	#include <stdlib.h>
	34	#include <stdio.h>
	35	#include <string.h>
	36	#include <unistd.h>
3bcced4c	37	#include <paths.h>
3bcced4c	38
b3ef88dc	39	#ifdef HAVE_UTIL_H
	40	# include <util.h>
	41	#endif
	42
	43	#ifdef HAVE_LIBUTIL_H
	44	# include <libutil.h>
	45	#endif
	46
3bcced4c	47	#include "openbsd-compat/sys-queue.h"
	48	#include "xmalloc.h"
	49	#include "log.h"
	50	#include "ssh.h"
	51	#include "pathnames.h"
	52	#include "misc.h"
	53	#include "match.h"
	54	#include "buffer.h"
	55	#include "channels.h"
	56	#include "msg.h"
	57	#include "packet.h"
	58	#include "monitor_fdpass.h"
	59	#include "sshpty.h"
	60	#include "key.h"
	61	#include "readconf.h"
	62	#include "clientloop.h"
	63
	64	/* from ssh.c */
	65	extern int tty_flag;
	66	extern Options options;
	67	extern int stdin_null_flag;
	68	extern char *host;
	69	int subsystem_flag;
	70	extern Buffer command;
	71
	72	/* fd to control socket */
	73	int muxserver_sock = -1;
	74
	75	/* Multiplexing control command */
	76	u_int muxclient_command = 0;
	77
	78	/* Set when signalled. */
	79	static volatile sig_atomic_t muxclient_terminate = 0;
	80
	81	/* PID of multiplex server */
	82	static u_int muxserver_pid = 0;
	83
	84
	85	/* ** Multiplexing master support */
	86
	87	/* Prepare a mux master to listen on a Unix domain socket. */
	88	void
	89	muxserver_listen(void)
	90	{
	91	struct sockaddr_un addr;
	92	mode_t old_umask;
	93	int addr_len;
	94
	95	if (options.control_path == NULL \|\|
	96	options.control_master == SSHCTL_MASTER_NO)
	97	return;
	98
	99	debug("setting up multiplex master socket");
	100
	101	memset(&addr, '\0', sizeof(addr));
	102	addr.sun_family = AF_UNIX;
	103	addr_len = offsetof(struct sockaddr_un, sun_path) +
	104	strlen(options.control_path) + 1;
	105
	106	if (strlcpy(addr.sun_path, options.control_path,
	107	sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
	108	fatal("ControlPath too long");
	109
	110	if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
111	fatal("%s socket(): %s", __func__, strerror(errno));
112
113	old_umask = umask(0177);
114	if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) {
115	muxserver_sock = -1;
116	if (errno == EINVAL \|\| errno == EADDRINUSE)
117	fatal("ControlSocket %s already exists",
118	options.control_path);
119	else
120	fatal("%s bind(): %s", __func__, strerror(errno));
121	}
122	umask(old_umask);
123
124	if (listen(muxserver_sock, 64) == -1)
125	fatal("%s listen(): %s", __func__, strerror(errno));
126
127	set_nonblock(muxserver_sock);
128	}
129
130	/* Callback on open confirmation in mux master for a mux client session. */
131	static void
132	client_extra_session2_setup(int id, void *arg)
133	{
134	struct mux_session_confirm_ctx *cctx = arg;
135	const char *display;
136	Channel *c;
137	int i;
138
139	if (cctx == NULL)
140	fatal("%s: cctx == NULL", __func__);
141	if ((c = channel_lookup(id)) == NULL)
142	fatal("%s: no channel for id %d", __func__, id);
143
144	display = getenv("DISPLAY");
145	if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
146	char proto, data;
147	/* Get reasonable local authentication information. */
148	client_x11_get_proto(display, options.xauth_location,
149	options.forward_x11_trusted, &proto, &data);
150	/* Request forwarding with authentication spoofing. */
151	debug("Requesting X11 forwarding with authentication spoofing.");
152	x11_request_forwarding_with_spoofing(id, display, proto, data);
153	/* XXX wait for reply */
154	}
155
156	if (cctx->want_agent_fwd && options.forward_agent) {
157	debug("Requesting authentication agent forwarding.");
158	channel_request_start(id, "auth-agent-req@openssh.com", 0);
159	packet_send();
160	}
161
162	client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
163	cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
164
165	c->open_confirm_ctx = NULL;
166	buffer_free(&cctx->cmd);
167	xfree(cctx->term);
168	if (cctx->env != NULL) {
169	for (i = 0; cctx->env[i] != NULL; i++)
170	xfree(cctx->env[i]);
171	xfree(cctx->env);
172	}
173	xfree(cctx);
174	}
175
176	/*
177	* Accept a connection on the mux master socket and process the
178	* client's request. Returns flag indicating whether mux master should
179	* begin graceful close.
180	*/
181	int
182	muxserver_accept_control(void)
183	{
184	Buffer m;
185	Channel *c;
186	int client_fd, new_fd[3], ver, allowed, window, packetmax;
187	socklen_t addrlen;
188	struct sockaddr_storage addr;
189	struct mux_session_confirm_ctx *cctx;
190	char *cmd;
191	u_int i, j, len, env_len, mux_command, flags;
192	uid_t euid;
193	gid_t egid;
194	int start_close = 0;
195
196	/*
197	* Accept connection on control socket
198	*/
199	memset(&addr, 0, sizeof(addr));
200	addrlen = sizeof(addr);
201	if ((client_fd = accept(muxserver_sock,
202	(struct sockaddr*)&addr, &addrlen)) == -1) {
203	error("%s accept: %s", __func__, strerror(errno));
204	return 0;
205	}
206
207	if (getpeereid(client_fd, &euid, &egid) < 0) {
208	error("%s getpeereid failed: %s", __func__, strerror(errno));
209	close(client_fd);
210	return 0;
211	}
212	if ((euid != 0) && (getuid() != euid)) {
213	error("control mode uid mismatch: peer euid %u != uid %u",
214	(u_int) euid, (u_int) getuid());
215	close(client_fd);
216	return 0;
217	}
218
219	/* XXX handle asynchronously */
220	unset_nonblock(client_fd);
221
222	/* Read command */
223	buffer_init(&m);
224	if (ssh_msg_recv(client_fd, &m) == -1) {
225	error("%s: client msg_recv failed", __func__);
226	close(client_fd);
227	buffer_free(&m);
228	return 0;
229	}
230	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
231	error("%s: wrong client version %d", __func__, ver);
232	buffer_free(&m);
233	close(client_fd);
234	return 0;
235	}
236
237	allowed = 1;
238	mux_command = buffer_get_int(&m);
239	flags = buffer_get_int(&m);
240
241	buffer_clear(&m);
242
243	switch (mux_command) {
244	case SSHMUX_COMMAND_OPEN:
245	if (options.control_master == SSHCTL_MASTER_ASK \|\|
246	options.control_master == SSHCTL_MASTER_AUTO_ASK)
247	allowed = ask_permission("Allow shared connection "
248	"to %s? ", host);
249	/* continue below */
250	break;
251	case SSHMUX_COMMAND_TERMINATE:
252	if (options.control_master == SSHCTL_MASTER_ASK \|\|
253	options.control_master == SSHCTL_MASTER_AUTO_ASK)
254	allowed = ask_permission("Terminate shared connection "
255	"to %s? ", host);
256	if (allowed)
257	start_close = 1;
258	/* FALLTHROUGH */
259	case SSHMUX_COMMAND_ALIVE_CHECK:
260	/* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */
261	buffer_clear(&m);
262	buffer_put_int(&m, allowed);
263	buffer_put_int(&m, getpid());
264	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
265	error("%s: client msg_send failed", __func__);
266	close(client_fd);
267	buffer_free(&m);
268	return start_close;
269	}
270	buffer_free(&m);
271	close(client_fd);
272	return start_close;
273	default:
274	error("Unsupported command %d", mux_command);
275	buffer_free(&m);
276	close(client_fd);
277	return 0;
278	}
279
280	/* Reply for SSHMUX_COMMAND_OPEN */
281	buffer_clear(&m);
282	buffer_put_int(&m, allowed);
283	buffer_put_int(&m, getpid());
284	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
285	error("%s: client msg_send failed", __func__);
286	close(client_fd);
287	buffer_free(&m);
288	return 0;
289	}
290
291	if (!allowed) {
292	error("Refused control connection");
293	close(client_fd);
294	buffer_free(&m);
295	return 0;
296	}
297
298	buffer_clear(&m);
299	if (ssh_msg_recv(client_fd, &m) == -1) {
300	error("%s: client msg_recv failed", __func__);
301	close(client_fd);
302	buffer_free(&m);
303	return 0;
304	}
305	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
306	error("%s: wrong client version %d", __func__, ver);
307	buffer_free(&m);
308	close(client_fd);
309	return 0;
310	}
311
312	cctx = xcalloc(1, sizeof(*cctx));
313	cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0;
314	cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0;
315	cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0;
316	cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0;
317	cctx->term = buffer_get_string(&m, &len);
318
319	cmd = buffer_get_string(&m, &len);
320	buffer_init(&cctx->cmd);
321	buffer_append(&cctx->cmd, cmd, strlen(cmd));
322
323	env_len = buffer_get_int(&m);
324	env_len = MIN(env_len, 4096);
325	debug3("%s: receiving %d env vars", __func__, env_len);
326	if (env_len != 0) {
327	cctx->env = xcalloc(env_len + 1, sizeof(*cctx->env));
328	for (i = 0; i < env_len; i++)
329	cctx->env[i] = buffer_get_string(&m, &len);
330	cctx->env[i] = NULL;
331	}
332
333	debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__,
334	cctx->want_tty, cctx->want_subsys, cmd);
335	xfree(cmd);
336
337	/* Gather fds from client */
338	for(i = 0; i < 3; i++) {
339	if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) {
340	error("%s: failed to receive fd %d from slave",
341	__func__, i);
342	for (j = 0; j < i; j++)
343	close(new_fd[j]);
344	for (j = 0; j < env_len; j++)
345	xfree(cctx->env[j]);
346	if (env_len > 0)
347	xfree(cctx->env);
348	xfree(cctx->term);
349	buffer_free(&cctx->cmd);
350	close(client_fd);
351	xfree(cctx);
352	return 0;
353	}
354	}
355
356	debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
357	new_fd[0], new_fd[1], new_fd[2]);
358
359	/* Try to pick up ttymodes from client before it goes raw */
360	if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
361	error("%s: tcgetattr: %s", __func__, strerror(errno));
362
363	/* This roundtrip is just for synchronisation of ttymodes */
364	buffer_clear(&m);
365	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
366	error("%s: client msg_send failed", __func__);
367	close(client_fd);
368	close(new_fd[0]);
369	close(new_fd[1]);
370	close(new_fd[2]);
371	buffer_free(&m);
372	xfree(cctx->term);
373	if (env_len != 0) {
374	for (i = 0; i < env_len; i++)
375	xfree(cctx->env[i]);
376	xfree(cctx->env);
377	}
378	return 0;
379	}
380	buffer_free(&m);
381
382	/* enable nonblocking unless tty */
383	if (!isatty(new_fd[0]))
384	set_nonblock(new_fd[0]);
385	if (!isatty(new_fd[1]))
386	set_nonblock(new_fd[1]);
387	if (!isatty(new_fd[2]))
388	set_nonblock(new_fd[2]);
389
390	set_nonblock(client_fd);
391
392	window = CHAN_SES_WINDOW_DEFAULT;
393	packetmax = CHAN_SES_PACKET_DEFAULT;
394	if (cctx->want_tty) {
395	window >>= 1;
396	packetmax >>= 1;
397	}
398
399	c = channel_new("session", SSH_CHANNEL_OPENING,
400	new_fd[0], new_fd[1], new_fd[2], window, packetmax,
401	CHAN_EXTENDED_WRITE, "client-session", /nonblock/0);
402
403	/* XXX */
404	c->ctl_fd = client_fd;
405
406	debug3("%s: channel_new: %d", __func__, c->self);
407
408	channel_send_open(c->self);
409	channel_register_open_confirm(c->self,
410	client_extra_session2_setup, cctx);
411	return 0;
412	}
413
414	/* ** Multiplexing client support */
415
416	/* Exit signal handler */
417	static void
418	control_client_sighandler(int signo)
419	{
420	muxclient_terminate = signo;
421	}
422
423	/*
424	* Relay signal handler - used to pass some signals from mux client to
425	* mux master.
426	*/
427	static void
428	control_client_sigrelay(int signo)
429	{
430	int save_errno = errno;
431
432	if (muxserver_pid > 1)
433	kill(muxserver_pid, signo);
434
435	errno = save_errno;
436	}
437
438	/* Check mux client environment variables before passing them to mux master. */
439	static int
440	env_permitted(char *env)
441	{
442	int i, ret;
443	char name[1024], *cp;
444
445	if ((cp = strchr(env, '=')) == NULL \|\| cp == env)
446	return (0);
447	ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
448	if (ret <= 0 \|\| (size_t)ret >= sizeof(name))
449	fatal("env_permitted: name '%.100s...' too long", env);
450
451	for (i = 0; i < options.num_send_env; i++)
452	if (match_pattern(name, options.send_env[i]))
453	return (1);
454
455	return (0);
456	}
457
458	/* Multiplex client main loop. */
459	void
460	muxclient(const char *path)
461	{
462	struct sockaddr_un addr;
463	int i, r, fd, sock, exitval[2], num_env, addr_len;
464	Buffer m;
465	char *term;
466	extern char **environ;
467	u_int flags;
468
469	if (muxclient_command == 0)
470	muxclient_command = SSHMUX_COMMAND_OPEN;
471
472	switch (options.control_master) {
473	case SSHCTL_MASTER_AUTO:
474	case SSHCTL_MASTER_AUTO_ASK:
475	debug("auto-mux: Trying existing master");
476	/* FALLTHROUGH */
477	case SSHCTL_MASTER_NO:
478	break;
479	default:
480	return;
481	}
482
483	memset(&addr, '\0', sizeof(addr));
484	addr.sun_family = AF_UNIX;
485	addr_len = offsetof(struct sockaddr_un, sun_path) +
486	strlen(path) + 1;
487
488	if (strlcpy(addr.sun_path, path,
489	sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
490	fatal("ControlPath too long");
491
492	if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
493	fatal("%s socket(): %s", __func__, strerror(errno));
494
495	if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
496	if (muxclient_command != SSHMUX_COMMAND_OPEN) {
497	fatal("Control socket connect(%.100s): %s", path,
498	strerror(errno));
499	}
500	if (errno == ENOENT)
501	debug("Control socket \"%.100s\" does not exist", path);
502	else {
503	error("Control socket connect(%.100s): %s", path,
504	strerror(errno));
505	}
506	close(sock);
507	return;
508	}
509
510	if (stdin_null_flag) {
511	if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
512	fatal("open(/dev/null): %s", strerror(errno));
513	if (dup2(fd, STDIN_FILENO) == -1)
514	fatal("dup2: %s", strerror(errno));
515	if (fd > STDERR_FILENO)
516	close(fd);
517	}
518
519	term = getenv("TERM");
520
521	flags = 0;
522	if (tty_flag)
523	flags \|= SSHMUX_FLAG_TTY;
524	if (subsystem_flag)
525	flags \|= SSHMUX_FLAG_SUBSYS;
526	if (options.forward_x11)
527	flags \|= SSHMUX_FLAG_X11_FWD;
528	if (options.forward_agent)
529	flags \|= SSHMUX_FLAG_AGENT_FWD;
530
531	signal(SIGPIPE, SIG_IGN);
532
533	buffer_init(&m);
534
535	/* Send our command to server */
536	buffer_put_int(&m, muxclient_command);
537	buffer_put_int(&m, flags);
538	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
539	fatal("%s: msg_send", __func__);
540	buffer_clear(&m);
541
542	/* Get authorisation status and PID of controlee */
543	if (ssh_msg_recv(sock, &m) == -1)
544	fatal("%s: msg_recv", __func__);
545	if (buffer_get_char(&m) != SSHMUX_VER)
546	fatal("%s: wrong version", __func__);
547	if (buffer_get_int(&m) != 1)
548	fatal("Connection to master denied");
549	muxserver_pid = buffer_get_int(&m);
550
551	buffer_clear(&m);
552
553	switch (muxclient_command) {
554	case SSHMUX_COMMAND_ALIVE_CHECK:
555	fprintf(stderr, "Master running (pid=%d)\r\n",
556	muxserver_pid);
557	exit(0);
558	case SSHMUX_COMMAND_TERMINATE:
559	fprintf(stderr, "Exit request sent.\r\n");
560	exit(0);
561	case SSHMUX_COMMAND_OPEN:
562	/* continue below */
563	break;
564	default:
565	fatal("silly muxclient_command %d", muxclient_command);
566	}
567
568	/* SSHMUX_COMMAND_OPEN */
569	buffer_put_cstring(&m, term ? term : "");
570	buffer_append(&command, "\0", 1);
571	buffer_put_cstring(&m, buffer_ptr(&command));
572
573	if (options.num_send_env == 0 \|\| environ == NULL) {
574	buffer_put_int(&m, 0);
575	} else {
576	/* Pass environment */
577	num_env = 0;
578	for (i = 0; environ[i] != NULL; i++)
579	if (env_permitted(environ[i]))
580	num_env++; /* Count */
581
582	buffer_put_int(&m, num_env);
583
584	for (i = 0; environ[i] != NULL && num_env >= 0; i++)
585	if (env_permitted(environ[i])) {
586	num_env--;
587	buffer_put_cstring(&m, environ[i]);
588	}
589	}
590
591	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
592	fatal("%s: msg_send", __func__);
593
594	if (mm_send_fd(sock, STDIN_FILENO) == -1 \|\|
595	mm_send_fd(sock, STDOUT_FILENO) == -1 \|\|
596	mm_send_fd(sock, STDERR_FILENO) == -1)
597	fatal("%s: send fds failed", __func__);
598
599	/* Wait for reply, so master has a chance to gather ttymodes */
600	buffer_clear(&m);
601	if (ssh_msg_recv(sock, &m) == -1)
602	fatal("%s: msg_recv", __func__);
603	if (buffer_get_char(&m) != SSHMUX_VER)
604	fatal("%s: wrong version", __func__);
605	buffer_free(&m);
606
607	signal(SIGHUP, control_client_sighandler);
608	signal(SIGINT, control_client_sighandler);
609	signal(SIGTERM, control_client_sighandler);
610	signal(SIGWINCH, control_client_sigrelay);
611
612	if (tty_flag)
613	enter_raw_mode();
614
615	/*
616	* Stick around until the controlee closes the client_fd.
617	* Before it does, it is expected to write this process' exit
618	* value (one int). This process must read the value and wait for
619	* the closure of the client_fd; if this one closes early, the
620	* multiplex master will terminate early too (possibly losing data).
621	*/
622	exitval[0] = 0;
623	for (i = 0; !muxclient_terminate && i < (int)sizeof(exitval);) {
624	r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
625	if (r == 0) {
626	debug2("Received EOF from master");
627	break;
628	}
629	if (r == -1) {
630	if (errno == EINTR)
631	continue;
632	fatal("%s: read %s", __func__, strerror(errno));
633	}
634	i += r;
635	}
636
637	close(sock);
638	leave_raw_mode();
639	if (i > (int)sizeof(int))
640	fatal("%s: master returned too much data (%d > %lu)",
641	__func__, i, sizeof(int));
642	if (muxclient_terminate) {
643	debug2("Exiting on signal %d", muxclient_terminate);
644	exitval[0] = 255;
645	} else if (i < (int)sizeof(int)) {
646	debug2("Control master terminated unexpectedly");
647	exitval[0] = 255;
648	} else
649	debug2("Received exit status from master %d", exitval[0]);
650
651	if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
652	fprintf(stderr, "Shared connection to %s closed.\r\n", host);
653
654	exit(exitval[0]);
655	}