blob: 79f83768b334012fab5c177fc66cc3cd54310759 [file] [log] [blame]
Darren Tucker47e713b2008-06-14 09:01:54 +10001/* $OpenBSD: mux.c,v 1.7 2008/06/13 17:21:20 dtucker Exp $ */
Damien Millerb1cbfa22008-05-19 16:00:08 +10002/*
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
Damien Millera7058ec2008-05-20 08:57:06 +100020#include "includes.h"
21
Darren Tucker2fb66ca2008-06-13 04:49:33 +100022/*
23 * TODO:
24 * 1. partial reads in muxserver_accept_control (maybe make channels
25 * from accepted connections)
26 * 2. Better signalling from master to slave, especially passing of
27 * error messages
28 * 3. Better fall-back from mux slave error to new connection.
29 * 3. Add/delete forwardings via slave
30 * 4. ExitOnForwardingFailure (after #3 obviously)
31 * 5. Maybe extension mechanisms for multi-X11/multi-agent forwarding
32 * 6. Document the mux mini-protocol somewhere.
Darren Tuckerba69c7a2008-06-13 04:54:05 +100033 * 7. Support ~^Z in mux slaves.
34 * 8. Inspect or control sessions in master.
35 * 9. If we ever support the "signal" channel request, send signals on
36 * sessions in master.
Darren Tucker2fb66ca2008-06-13 04:49:33 +100037 */
38
Damien Millerb1cbfa22008-05-19 16:00:08 +100039#include <sys/types.h>
40#include <sys/param.h>
41#include <sys/stat.h>
42#include <sys/socket.h>
43#include <sys/un.h>
44
45#include <errno.h>
46#include <fcntl.h>
47#include <signal.h>
48#include <stdarg.h>
49#include <stddef.h>
50#include <stdlib.h>
51#include <stdio.h>
52#include <string.h>
53#include <unistd.h>
Darren Tuckerce38d822008-06-07 06:25:15 +100054#ifdef HAVE_PATHS_H
Damien Millerb1cbfa22008-05-19 16:00:08 +100055#include <paths.h>
Darren Tuckerce38d822008-06-07 06:25:15 +100056#endif
Damien Millerb1cbfa22008-05-19 16:00:08 +100057
Damien Millera7058ec2008-05-20 08:57:06 +100058#ifdef HAVE_UTIL_H
59# include <util.h>
60#endif
61
62#ifdef HAVE_LIBUTIL_H
63# include <libutil.h>
64#endif
65
Damien Millerb1cbfa22008-05-19 16:00:08 +100066#include "openbsd-compat/sys-queue.h"
67#include "xmalloc.h"
68#include "log.h"
69#include "ssh.h"
70#include "pathnames.h"
71#include "misc.h"
72#include "match.h"
73#include "buffer.h"
74#include "channels.h"
75#include "msg.h"
76#include "packet.h"
77#include "monitor_fdpass.h"
78#include "sshpty.h"
79#include "key.h"
80#include "readconf.h"
81#include "clientloop.h"
82
83/* from ssh.c */
84extern int tty_flag;
85extern Options options;
86extern int stdin_null_flag;
87extern char *host;
88int subsystem_flag;
89extern Buffer command;
90
Darren Tucker2fb66ca2008-06-13 04:49:33 +100091/* Context for session open confirmation callback */
92struct mux_session_confirm_ctx {
93 int want_tty;
94 int want_subsys;
95 int want_x_fwd;
96 int want_agent_fwd;
97 Buffer cmd;
98 char *term;
99 struct termios tio;
100 char **env;
101};
102
Damien Millerb1cbfa22008-05-19 16:00:08 +1000103/* fd to control socket */
104int muxserver_sock = -1;
105
106/* Multiplexing control command */
107u_int muxclient_command = 0;
108
109/* Set when signalled. */
110static volatile sig_atomic_t muxclient_terminate = 0;
111
112/* PID of multiplex server */
113static u_int muxserver_pid = 0;
114
115
116/* ** Multiplexing master support */
117
118/* Prepare a mux master to listen on a Unix domain socket. */
119void
120muxserver_listen(void)
121{
122 struct sockaddr_un addr;
123 mode_t old_umask;
124 int addr_len;
125
126 if (options.control_path == NULL ||
127 options.control_master == SSHCTL_MASTER_NO)
128 return;
129
130 debug("setting up multiplex master socket");
131
132 memset(&addr, '\0', sizeof(addr));
133 addr.sun_family = AF_UNIX;
134 addr_len = offsetof(struct sockaddr_un, sun_path) +
135 strlen(options.control_path) + 1;
136
137 if (strlcpy(addr.sun_path, options.control_path,
138 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
139 fatal("ControlPath too long");
140
141 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
142 fatal("%s socket(): %s", __func__, strerror(errno));
143
144 old_umask = umask(0177);
145 if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) {
146 muxserver_sock = -1;
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000147 if (errno == EINVAL || errno == EADDRINUSE) {
148 error("ControlSocket %s already exists, "
149 "disabling multiplexing", options.control_path);
150 close(muxserver_sock);
151 muxserver_sock = -1;
152 xfree(options.control_path);
153 options.control_path = NULL;
154 options.control_master = SSHCTL_MASTER_NO;
155 return;
156 } else
Damien Millerb1cbfa22008-05-19 16:00:08 +1000157 fatal("%s bind(): %s", __func__, strerror(errno));
158 }
159 umask(old_umask);
160
161 if (listen(muxserver_sock, 64) == -1)
162 fatal("%s listen(): %s", __func__, strerror(errno));
163
164 set_nonblock(muxserver_sock);
165}
166
167/* Callback on open confirmation in mux master for a mux client session. */
168static void
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000169mux_session_confirm(int id, void *arg)
Damien Millerb1cbfa22008-05-19 16:00:08 +1000170{
171 struct mux_session_confirm_ctx *cctx = arg;
172 const char *display;
173 Channel *c;
174 int i;
175
176 if (cctx == NULL)
177 fatal("%s: cctx == NULL", __func__);
178 if ((c = channel_lookup(id)) == NULL)
179 fatal("%s: no channel for id %d", __func__, id);
180
181 display = getenv("DISPLAY");
182 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
183 char *proto, *data;
184 /* Get reasonable local authentication information. */
185 client_x11_get_proto(display, options.xauth_location,
186 options.forward_x11_trusted, &proto, &data);
187 /* Request forwarding with authentication spoofing. */
188 debug("Requesting X11 forwarding with authentication spoofing.");
189 x11_request_forwarding_with_spoofing(id, display, proto, data);
190 /* XXX wait for reply */
191 }
192
193 if (cctx->want_agent_fwd && options.forward_agent) {
194 debug("Requesting authentication agent forwarding.");
195 channel_request_start(id, "auth-agent-req@openssh.com", 0);
196 packet_send();
197 }
198
199 client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
200 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
201
202 c->open_confirm_ctx = NULL;
203 buffer_free(&cctx->cmd);
204 xfree(cctx->term);
205 if (cctx->env != NULL) {
206 for (i = 0; cctx->env[i] != NULL; i++)
207 xfree(cctx->env[i]);
208 xfree(cctx->env);
209 }
210 xfree(cctx);
211}
212
213/*
214 * Accept a connection on the mux master socket and process the
215 * client's request. Returns flag indicating whether mux master should
216 * begin graceful close.
217 */
218int
219muxserver_accept_control(void)
220{
221 Buffer m;
222 Channel *c;
223 int client_fd, new_fd[3], ver, allowed, window, packetmax;
224 socklen_t addrlen;
225 struct sockaddr_storage addr;
226 struct mux_session_confirm_ctx *cctx;
227 char *cmd;
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000228 u_int i, j, len, env_len, mux_command, flags, escape_char;
Damien Millerb1cbfa22008-05-19 16:00:08 +1000229 uid_t euid;
230 gid_t egid;
231 int start_close = 0;
232
233 /*
234 * Accept connection on control socket
235 */
236 memset(&addr, 0, sizeof(addr));
237 addrlen = sizeof(addr);
238 if ((client_fd = accept(muxserver_sock,
239 (struct sockaddr*)&addr, &addrlen)) == -1) {
240 error("%s accept: %s", __func__, strerror(errno));
241 return 0;
242 }
243
244 if (getpeereid(client_fd, &euid, &egid) < 0) {
245 error("%s getpeereid failed: %s", __func__, strerror(errno));
246 close(client_fd);
247 return 0;
248 }
249 if ((euid != 0) && (getuid() != euid)) {
250 error("control mode uid mismatch: peer euid %u != uid %u",
251 (u_int) euid, (u_int) getuid());
252 close(client_fd);
253 return 0;
254 }
255
256 /* XXX handle asynchronously */
257 unset_nonblock(client_fd);
258
259 /* Read command */
260 buffer_init(&m);
261 if (ssh_msg_recv(client_fd, &m) == -1) {
262 error("%s: client msg_recv failed", __func__);
263 close(client_fd);
264 buffer_free(&m);
265 return 0;
266 }
267 if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
268 error("%s: wrong client version %d", __func__, ver);
269 buffer_free(&m);
270 close(client_fd);
271 return 0;
272 }
273
274 allowed = 1;
275 mux_command = buffer_get_int(&m);
276 flags = buffer_get_int(&m);
277
278 buffer_clear(&m);
279
280 switch (mux_command) {
281 case SSHMUX_COMMAND_OPEN:
282 if (options.control_master == SSHCTL_MASTER_ASK ||
283 options.control_master == SSHCTL_MASTER_AUTO_ASK)
284 allowed = ask_permission("Allow shared connection "
285 "to %s? ", host);
286 /* continue below */
287 break;
288 case SSHMUX_COMMAND_TERMINATE:
289 if (options.control_master == SSHCTL_MASTER_ASK ||
290 options.control_master == SSHCTL_MASTER_AUTO_ASK)
291 allowed = ask_permission("Terminate shared connection "
292 "to %s? ", host);
293 if (allowed)
294 start_close = 1;
295 /* FALLTHROUGH */
296 case SSHMUX_COMMAND_ALIVE_CHECK:
297 /* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */
298 buffer_clear(&m);
299 buffer_put_int(&m, allowed);
300 buffer_put_int(&m, getpid());
301 if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
302 error("%s: client msg_send failed", __func__);
303 close(client_fd);
304 buffer_free(&m);
305 return start_close;
306 }
307 buffer_free(&m);
308 close(client_fd);
309 return start_close;
310 default:
311 error("Unsupported command %d", mux_command);
312 buffer_free(&m);
313 close(client_fd);
314 return 0;
315 }
316
317 /* Reply for SSHMUX_COMMAND_OPEN */
318 buffer_clear(&m);
319 buffer_put_int(&m, allowed);
320 buffer_put_int(&m, getpid());
321 if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
322 error("%s: client msg_send failed", __func__);
323 close(client_fd);
324 buffer_free(&m);
325 return 0;
326 }
327
328 if (!allowed) {
329 error("Refused control connection");
330 close(client_fd);
331 buffer_free(&m);
332 return 0;
333 }
334
335 buffer_clear(&m);
336 if (ssh_msg_recv(client_fd, &m) == -1) {
337 error("%s: client msg_recv failed", __func__);
338 close(client_fd);
339 buffer_free(&m);
340 return 0;
341 }
342 if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
343 error("%s: wrong client version %d", __func__, ver);
344 buffer_free(&m);
345 close(client_fd);
346 return 0;
347 }
348
349 cctx = xcalloc(1, sizeof(*cctx));
350 cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0;
351 cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0;
352 cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0;
353 cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0;
354 cctx->term = buffer_get_string(&m, &len);
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000355 escape_char = buffer_get_int(&m);
Damien Millerb1cbfa22008-05-19 16:00:08 +1000356
357 cmd = buffer_get_string(&m, &len);
358 buffer_init(&cctx->cmd);
359 buffer_append(&cctx->cmd, cmd, strlen(cmd));
360
361 env_len = buffer_get_int(&m);
362 env_len = MIN(env_len, 4096);
363 debug3("%s: receiving %d env vars", __func__, env_len);
364 if (env_len != 0) {
365 cctx->env = xcalloc(env_len + 1, sizeof(*cctx->env));
366 for (i = 0; i < env_len; i++)
367 cctx->env[i] = buffer_get_string(&m, &len);
368 cctx->env[i] = NULL;
369 }
370
371 debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__,
372 cctx->want_tty, cctx->want_subsys, cmd);
373 xfree(cmd);
374
375 /* Gather fds from client */
376 for(i = 0; i < 3; i++) {
377 if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) {
378 error("%s: failed to receive fd %d from slave",
379 __func__, i);
380 for (j = 0; j < i; j++)
381 close(new_fd[j]);
382 for (j = 0; j < env_len; j++)
383 xfree(cctx->env[j]);
384 if (env_len > 0)
385 xfree(cctx->env);
386 xfree(cctx->term);
387 buffer_free(&cctx->cmd);
388 close(client_fd);
389 xfree(cctx);
390 return 0;
391 }
392 }
393
394 debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
395 new_fd[0], new_fd[1], new_fd[2]);
396
397 /* Try to pick up ttymodes from client before it goes raw */
398 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
399 error("%s: tcgetattr: %s", __func__, strerror(errno));
400
401 /* This roundtrip is just for synchronisation of ttymodes */
402 buffer_clear(&m);
403 if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
404 error("%s: client msg_send failed", __func__);
405 close(client_fd);
406 close(new_fd[0]);
407 close(new_fd[1]);
408 close(new_fd[2]);
409 buffer_free(&m);
410 xfree(cctx->term);
411 if (env_len != 0) {
412 for (i = 0; i < env_len; i++)
413 xfree(cctx->env[i]);
414 xfree(cctx->env);
415 }
416 return 0;
417 }
418 buffer_free(&m);
419
420 /* enable nonblocking unless tty */
421 if (!isatty(new_fd[0]))
422 set_nonblock(new_fd[0]);
423 if (!isatty(new_fd[1]))
424 set_nonblock(new_fd[1]);
425 if (!isatty(new_fd[2]))
426 set_nonblock(new_fd[2]);
427
428 set_nonblock(client_fd);
429
430 window = CHAN_SES_WINDOW_DEFAULT;
431 packetmax = CHAN_SES_PACKET_DEFAULT;
432 if (cctx->want_tty) {
433 window >>= 1;
434 packetmax >>= 1;
435 }
436
437 c = channel_new("session", SSH_CHANNEL_OPENING,
438 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
439 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
440
Damien Millerb1cbfa22008-05-19 16:00:08 +1000441 c->ctl_fd = client_fd;
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000442 if (cctx->want_tty && escape_char != 0xffffffff) {
443 channel_register_filter(c->self,
444 client_simple_escape_filter, NULL,
Darren Tucker84c56f52008-06-13 04:55:46 +1000445 client_filter_cleanup,
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000446 client_new_escape_filter_ctx((int)escape_char));
447 }
Damien Millerb1cbfa22008-05-19 16:00:08 +1000448
449 debug3("%s: channel_new: %d", __func__, c->self);
450
451 channel_send_open(c->self);
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000452 channel_register_open_confirm(c->self, mux_session_confirm, cctx);
Damien Millerb1cbfa22008-05-19 16:00:08 +1000453 return 0;
454}
455
456/* ** Multiplexing client support */
457
458/* Exit signal handler */
459static void
460control_client_sighandler(int signo)
461{
462 muxclient_terminate = signo;
463}
464
465/*
466 * Relay signal handler - used to pass some signals from mux client to
467 * mux master.
468 */
469static void
470control_client_sigrelay(int signo)
471{
472 int save_errno = errno;
473
474 if (muxserver_pid > 1)
475 kill(muxserver_pid, signo);
476
477 errno = save_errno;
478}
479
480/* Check mux client environment variables before passing them to mux master. */
481static int
482env_permitted(char *env)
483{
484 int i, ret;
485 char name[1024], *cp;
486
487 if ((cp = strchr(env, '=')) == NULL || cp == env)
488 return (0);
489 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
490 if (ret <= 0 || (size_t)ret >= sizeof(name))
491 fatal("env_permitted: name '%.100s...' too long", env);
492
493 for (i = 0; i < options.num_send_env; i++)
494 if (match_pattern(name, options.send_env[i]))
495 return (1);
496
497 return (0);
498}
499
500/* Multiplex client main loop. */
501void
502muxclient(const char *path)
503{
504 struct sockaddr_un addr;
505 int i, r, fd, sock, exitval[2], num_env, addr_len;
506 Buffer m;
507 char *term;
508 extern char **environ;
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000509 u_int allowed, flags;
Damien Millerb1cbfa22008-05-19 16:00:08 +1000510
511 if (muxclient_command == 0)
512 muxclient_command = SSHMUX_COMMAND_OPEN;
513
514 switch (options.control_master) {
515 case SSHCTL_MASTER_AUTO:
516 case SSHCTL_MASTER_AUTO_ASK:
517 debug("auto-mux: Trying existing master");
518 /* FALLTHROUGH */
519 case SSHCTL_MASTER_NO:
520 break;
521 default:
522 return;
523 }
524
525 memset(&addr, '\0', sizeof(addr));
526 addr.sun_family = AF_UNIX;
527 addr_len = offsetof(struct sockaddr_un, sun_path) +
528 strlen(path) + 1;
529
530 if (strlcpy(addr.sun_path, path,
531 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
532 fatal("ControlPath too long");
533
534 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
535 fatal("%s socket(): %s", __func__, strerror(errno));
536
537 if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
538 if (muxclient_command != SSHMUX_COMMAND_OPEN) {
539 fatal("Control socket connect(%.100s): %s", path,
540 strerror(errno));
541 }
542 if (errno == ENOENT)
543 debug("Control socket \"%.100s\" does not exist", path);
544 else {
545 error("Control socket connect(%.100s): %s", path,
546 strerror(errno));
547 }
548 close(sock);
549 return;
550 }
551
552 if (stdin_null_flag) {
553 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
554 fatal("open(/dev/null): %s", strerror(errno));
555 if (dup2(fd, STDIN_FILENO) == -1)
556 fatal("dup2: %s", strerror(errno));
557 if (fd > STDERR_FILENO)
558 close(fd);
559 }
560
561 term = getenv("TERM");
562
563 flags = 0;
564 if (tty_flag)
565 flags |= SSHMUX_FLAG_TTY;
566 if (subsystem_flag)
567 flags |= SSHMUX_FLAG_SUBSYS;
568 if (options.forward_x11)
569 flags |= SSHMUX_FLAG_X11_FWD;
570 if (options.forward_agent)
571 flags |= SSHMUX_FLAG_AGENT_FWD;
572
573 signal(SIGPIPE, SIG_IGN);
574
575 buffer_init(&m);
576
577 /* Send our command to server */
578 buffer_put_int(&m, muxclient_command);
579 buffer_put_int(&m, flags);
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000580 if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) {
581 error("%s: msg_send", __func__);
582 muxerr:
583 close(sock);
584 buffer_free(&m);
585 if (muxclient_command != SSHMUX_COMMAND_OPEN)
586 cleanup_exit(255);
587 logit("Falling back to non-multiplexed connection");
588 xfree(options.control_path);
589 options.control_path = NULL;
590 options.control_master = SSHCTL_MASTER_NO;
591 return;
592 }
Damien Millerb1cbfa22008-05-19 16:00:08 +1000593 buffer_clear(&m);
594
595 /* Get authorisation status and PID of controlee */
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000596 if (ssh_msg_recv(sock, &m) == -1) {
Darren Tucker47e713b2008-06-14 09:01:54 +1000597 error("%s: Did not receive reply from master", __func__);
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000598 goto muxerr;
599 }
600 if (buffer_get_char(&m) != SSHMUX_VER) {
Darren Tucker47e713b2008-06-14 09:01:54 +1000601 error("%s: Master replied with wrong version", __func__);
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000602 goto muxerr;
603 }
604 if (buffer_get_int_ret(&allowed, &m) != 0) {
605 error("%s: bad server reply", __func__);
606 goto muxerr;
607 }
608 if (allowed != 1) {
609 error("Connection to master denied");
610 goto muxerr;
611 }
Damien Millerb1cbfa22008-05-19 16:00:08 +1000612 muxserver_pid = buffer_get_int(&m);
613
614 buffer_clear(&m);
615
616 switch (muxclient_command) {
617 case SSHMUX_COMMAND_ALIVE_CHECK:
618 fprintf(stderr, "Master running (pid=%d)\r\n",
619 muxserver_pid);
620 exit(0);
621 case SSHMUX_COMMAND_TERMINATE:
622 fprintf(stderr, "Exit request sent.\r\n");
623 exit(0);
624 case SSHMUX_COMMAND_OPEN:
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000625 buffer_put_cstring(&m, term ? term : "");
626 if (options.escape_char == SSH_ESCAPECHAR_NONE)
627 buffer_put_int(&m, 0xffffffff);
628 else
629 buffer_put_int(&m, options.escape_char);
630 buffer_append(&command, "\0", 1);
631 buffer_put_cstring(&m, buffer_ptr(&command));
632
633 if (options.num_send_env == 0 || environ == NULL) {
634 buffer_put_int(&m, 0);
635 } else {
636 /* Pass environment */
637 num_env = 0;
638 for (i = 0; environ[i] != NULL; i++) {
639 if (env_permitted(environ[i]))
640 num_env++; /* Count */
641 }
642 buffer_put_int(&m, num_env);
643 for (i = 0; environ[i] != NULL && num_env >= 0; i++) {
644 if (env_permitted(environ[i])) {
645 num_env--;
646 buffer_put_cstring(&m, environ[i]);
647 }
648 }
649 }
Damien Millerb1cbfa22008-05-19 16:00:08 +1000650 break;
651 default:
Darren Tucker2fb66ca2008-06-13 04:49:33 +1000652 fatal("unrecognised muxclient_command %d", muxclient_command);
Damien Millerb1cbfa22008-05-19 16:00:08 +1000653 }
654
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000655 if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) {
656 error("%s: msg_send", __func__);
657 goto muxerr;
658 }
Damien Millerb1cbfa22008-05-19 16:00:08 +1000659
660 if (mm_send_fd(sock, STDIN_FILENO) == -1 ||
661 mm_send_fd(sock, STDOUT_FILENO) == -1 ||
Darren Tuckerca19bfe2008-06-13 10:24:03 +1000662 mm_send_fd(sock, STDERR_FILENO) == -1) {
663 error("%s: send fds failed", __func__);
664 goto muxerr;
665 }
666
667 /*
668 * Mux errors are non-recoverable from this point as the master
669 * has ownership of the session now.
670 */
Damien Millerb1cbfa22008-05-19 16:00:08 +1000671
672 /* Wait for reply, so master has a chance to gather ttymodes */
673 buffer_clear(&m);
674 if (ssh_msg_recv(sock, &m) == -1)
675 fatal("%s: msg_recv", __func__);
676 if (buffer_get_char(&m) != SSHMUX_VER)
677 fatal("%s: wrong version", __func__);
678 buffer_free(&m);
679
680 signal(SIGHUP, control_client_sighandler);
681 signal(SIGINT, control_client_sighandler);
682 signal(SIGTERM, control_client_sighandler);
683 signal(SIGWINCH, control_client_sigrelay);
684
685 if (tty_flag)
686 enter_raw_mode();
687
688 /*
689 * Stick around until the controlee closes the client_fd.
690 * Before it does, it is expected to write this process' exit
691 * value (one int). This process must read the value and wait for
692 * the closure of the client_fd; if this one closes early, the
693 * multiplex master will terminate early too (possibly losing data).
694 */
695 exitval[0] = 0;
696 for (i = 0; !muxclient_terminate && i < (int)sizeof(exitval);) {
697 r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
698 if (r == 0) {
699 debug2("Received EOF from master");
700 break;
701 }
702 if (r == -1) {
703 if (errno == EINTR)
704 continue;
705 fatal("%s: read %s", __func__, strerror(errno));
706 }
707 i += r;
708 }
709
710 close(sock);
711 leave_raw_mode();
712 if (i > (int)sizeof(int))
713 fatal("%s: master returned too much data (%d > %lu)",
Darren Tucker1adfd362008-06-13 10:58:10 +1000714 __func__, i, (u_long)sizeof(int));
Damien Millerb1cbfa22008-05-19 16:00:08 +1000715 if (muxclient_terminate) {
716 debug2("Exiting on signal %d", muxclient_terminate);
717 exitval[0] = 255;
718 } else if (i < (int)sizeof(int)) {
719 debug2("Control master terminated unexpectedly");
720 exitval[0] = 255;
721 } else
722 debug2("Received exit status from master %d", exitval[0]);
723
724 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
725 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
726
727 exit(exitval[0]);
728}