1 /* $OpenBSD: mux.c,v 1.29 2011/06/22 22:08:42 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
20 /*
21 * TODO:
22 * - Better signalling from master to slave, especially passing of
23 * error messages
24 * - Better fall-back from mux slave error to new connection.
25 * - ExitOnForwardingFailure
26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding
27 * - Support ~^Z in mux slaves.
28 * - Inspect or control sessions in master.
29 * - If we ever support the "signal" channel request, send signals on
30 * sessions in master.
31 */
32
33 #include "includes.h"
34
35 #include <sys/types.h>
36 #include <sys/param.h>
37 #include <sys/stat.h>
38 #include <sys/socket.h>
39 #include <sys/un.h>
40
41 #include <errno.h>
42 #include <fcntl.h>
43 #include <signal.h>
44 #include <stdarg.h>
45 #include <stddef.h>
46 #include <stdlib.h>
47 #include <stdio.h>
48 #include <string.h>
49 #include <unistd.h>
50 #ifdef HAVE_PATHS_H
51 #include <paths.h>
52 #endif
53
54 #ifdef HAVE_POLL_H
55 #include <poll.h>
56 #else
57 # ifdef HAVE_SYS_POLL_H
58 # include <sys/poll.h>
59 # endif
60 #endif
61
62 #ifdef HAVE_UTIL_H
63 # include <util.h>
64 #endif
65
66 #ifdef HAVE_LIBUTIL_H
67 # include <libutil.h>
68 #endif
69
70 #include "openbsd-compat/sys-queue.h"
71 #include "xmalloc.h"
72 #include "log.h"
73 #include "ssh.h"
74 #include "ssh2.h"
75 #include "pathnames.h"
76 #include "misc.h"
77 #include "match.h"
78 #include "buffer.h"
79 #include "channels.h"
80 #include "msg.h"
81 #include "packet.h"
82 #include "monitor_fdpass.h"
83 #include "sshpty.h"
84 #include "key.h"
85 #include "readconf.h"
86 #include "clientloop.h"
87
88 /* from ssh.c */
89 extern int tty_flag;
90 extern Options options;
91 extern int stdin_null_flag;
92 extern char *host;
93 extern int subsystem_flag;
94 extern Buffer command;
95 extern volatile sig_atomic_t quit_pending;
96 extern char *stdio_forward_host;
97 extern int stdio_forward_port;
98
99 /* Context for session open confirmation callback */
100 struct mux_session_confirm_ctx {
101 u_int want_tty;
102 u_int want_subsys;
103 u_int want_x_fwd;
104 u_int want_agent_fwd;
105 Buffer cmd;
106 char *term;
107 struct termios tio;
108 char **env;
109 u_int rid;
110 };
111
112 /* Context for global channel callback */
113 struct mux_channel_confirm_ctx {
114 u_int cid; /* channel id */
115 u_int rid; /* request id */
116 int fid; /* forward id */
117 };
118
119 /* fd to control socket */
120 int muxserver_sock = -1;
121
122 /* client request id */
123 u_int muxclient_request_id = 0;
124
125 /* Multiplexing control command */
126 u_int muxclient_command = 0;
127
128 /* Set when signalled. */
129 static volatile sig_atomic_t muxclient_terminate = 0;
130
131 /* PID of multiplex server */
132 static u_int muxserver_pid = 0;
133
134 static Channel *mux_listener_channel = NULL;
135
136 struct mux_master_state {
137 int hello_rcvd;
138 };
139
140 /* mux protocol messages */
141 #define MUX_MSG_HELLO 0x00000001
142 #define MUX_C_NEW_SESSION 0x10000002
143 #define MUX_C_ALIVE_CHECK 0x10000004
144 #define MUX_C_TERMINATE 0x10000005
145 #define MUX_C_OPEN_FWD 0x10000006
146 #define MUX_C_CLOSE_FWD 0x10000007
147 #define MUX_C_NEW_STDIO_FWD 0x10000008
148 #define MUX_C_STOP_LISTENING 0x10000009
149 #define MUX_S_OK 0x80000001
150 #define MUX_S_PERMISSION_DENIED 0x80000002
151 #define MUX_S_FAILURE 0x80000003
152 #define MUX_S_EXIT_MESSAGE 0x80000004
153 #define MUX_S_ALIVE 0x80000005
154 #define MUX_S_SESSION_OPENED 0x80000006
155 #define MUX_S_REMOTE_PORT 0x80000007
156 #define MUX_S_TTY_ALLOC_FAIL 0x80000008
157
158 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
159 #define MUX_FWD_LOCAL 1
160 #define MUX_FWD_REMOTE 2
161 #define MUX_FWD_DYNAMIC 3
162
163 static void mux_session_confirm(int, int, void *);
164
165 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *);
166 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *);
167 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *);
168 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *);
169 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *);
170 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *);
171 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *);
172 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *);
173
174 static const struct {
175 u_int type;
176 int (*handler)(u_int, Channel *, Buffer *, Buffer *);
177 } mux_master_handlers[] = {
178 { MUX_MSG_HELLO, process_mux_master_hello },
179 { MUX_C_NEW_SESSION, process_mux_new_session },
180 { MUX_C_ALIVE_CHECK, process_mux_alive_check },
181 { MUX_C_TERMINATE, process_mux_terminate },
182 { MUX_C_OPEN_FWD, process_mux_open_fwd },
183 { MUX_C_CLOSE_FWD, process_mux_close_fwd },
184 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd },
185 { MUX_C_STOP_LISTENING, process_mux_stop_listening },
186 { 0, NULL }
187 };
188
189 /* Cleanup callback fired on closure of mux slave _session_ channel */
190 /* ARGSUSED */
191 static void
mux_master_session_cleanup_cb(int cid,void * unused)192 mux_master_session_cleanup_cb(int cid, void *unused)
193 {
194 Channel *cc, *c = channel_by_id(cid);
195
196 debug3("%s: entering for channel %d", __func__, cid);
197 if (c == NULL)
198 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
199 if (c->ctl_chan != -1) {
200 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
201 fatal("%s: channel %d missing control channel %d",
202 __func__, c->self, c->ctl_chan);
203 c->ctl_chan = -1;
204 cc->remote_id = -1;
205 chan_rcvd_oclose(cc);
206 }
207 channel_cancel_cleanup(c->self);
208 }
209
210 /* Cleanup callback fired on closure of mux slave _control_ channel */
211 /* ARGSUSED */
212 static void
mux_master_control_cleanup_cb(int cid,void * unused)213 mux_master_control_cleanup_cb(int cid, void *unused)
214 {
215 Channel *sc, *c = channel_by_id(cid);
216
217 debug3("%s: entering for channel %d", __func__, cid);
218 if (c == NULL)
219 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
220 if (c->remote_id != -1) {
221 if ((sc = channel_by_id(c->remote_id)) == NULL)
222 fatal("%s: channel %d missing session channel %d",
223 __func__, c->self, c->remote_id);
224 c->remote_id = -1;
225 sc->ctl_chan = -1;
226 if (sc->type != SSH_CHANNEL_OPEN) {
227 debug2("%s: channel %d: not open", __func__, sc->self);
228 chan_mark_dead(sc);
229 } else {
230 if (sc->istate == CHAN_INPUT_OPEN)
231 chan_read_failed(sc);
232 if (sc->ostate == CHAN_OUTPUT_OPEN)
233 chan_write_failed(sc);
234 }
235 }
236 channel_cancel_cleanup(c->self);
237 }
238
239 /* Check mux client environment variables before passing them to mux master. */
240 static int
env_permitted(char * env)241 env_permitted(char *env)
242 {
243 int i, ret;
244 char name[1024], *cp;
245
246 if ((cp = strchr(env, '=')) == NULL || cp == env)
247 return 0;
248 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
249 if (ret <= 0 || (size_t)ret >= sizeof(name)) {
250 error("env_permitted: name '%.100s...' too long", env);
251 return 0;
252 }
253
254 for (i = 0; i < options.num_send_env; i++)
255 if (match_pattern(name, options.send_env[i]))
256 return 1;
257
258 return 0;
259 }
260
261 /* Mux master protocol message handlers */
262
263 static int
process_mux_master_hello(u_int rid,Channel * c,Buffer * m,Buffer * r)264 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r)
265 {
266 u_int ver;
267 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
268
269 if (state == NULL)
270 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self);
271 if (state->hello_rcvd) {
272 error("%s: HELLO received twice", __func__);
273 return -1;
274 }
275 if (buffer_get_int_ret(&ver, m) != 0) {
276 malf:
277 error("%s: malformed message", __func__);
278 return -1;
279 }
280 if (ver != SSHMUX_VER) {
281 error("Unsupported multiplexing protocol version %d "
282 "(expected %d)", ver, SSHMUX_VER);
283 return -1;
284 }
285 debug2("%s: channel %d slave version %u", __func__, c->self, ver);
286
287 /* No extensions are presently defined */
288 while (buffer_len(m) > 0) {
289 char *name = buffer_get_string_ret(m, NULL);
290 char *value = buffer_get_string_ret(m, NULL);
291
292 if (name == NULL || value == NULL) {
293 if (name != NULL)
294 xfree(name);
295 goto malf;
296 }
297 debug2("Unrecognised slave extension \"%s\"", name);
298 xfree(name);
299 xfree(value);
300 }
301 state->hello_rcvd = 1;
302 return 0;
303 }
304
305 static int
process_mux_new_session(u_int rid,Channel * c,Buffer * m,Buffer * r)306 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
307 {
308 Channel *nc;
309 struct mux_session_confirm_ctx *cctx;
310 char *reserved, *cmd, *cp;
311 u_int i, j, len, env_len, escape_char, window, packetmax;
312 int new_fd[3];
313
314 /* Reply for SSHMUX_COMMAND_OPEN */
315 cctx = xcalloc(1, sizeof(*cctx));
316 cctx->term = NULL;
317 cctx->rid = rid;
318 cmd = reserved = NULL;
319 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
320 buffer_get_int_ret(&cctx->want_tty, m) != 0 ||
321 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 ||
322 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 ||
323 buffer_get_int_ret(&cctx->want_subsys, m) != 0 ||
324 buffer_get_int_ret(&escape_char, m) != 0 ||
325 (cctx->term = buffer_get_string_ret(m, &len)) == NULL ||
326 (cmd = buffer_get_string_ret(m, &len)) == NULL) {
327 malf:
328 if (cmd != NULL)
329 xfree(cmd);
330 if (reserved != NULL)
331 xfree(reserved);
332 if (cctx->term != NULL)
333 xfree(cctx->term);
334 error("%s: malformed message", __func__);
335 return -1;
336 }
337 xfree(reserved);
338 reserved = NULL;
339
340 cctx->env = NULL;
341 env_len = 0;
342 while (buffer_len(m) > 0) {
343 #define MUX_MAX_ENV_VARS 4096
344 if ((cp = buffer_get_string_ret(m, &len)) == NULL) {
345 xfree(cmd);
346 goto malf;
347 }
348 if (!env_permitted(cp)) {
349 xfree(cp);
350 continue;
351 }
352 cctx->env = xrealloc(cctx->env, env_len + 2,
353 sizeof(*cctx->env));
354 cctx->env[env_len++] = cp;
355 cctx->env[env_len] = NULL;
356 if (env_len > MUX_MAX_ENV_VARS) {
357 error(">%d environment variables received, ignoring "
358 "additional", MUX_MAX_ENV_VARS);
359 break;
360 }
361 }
362
363 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, "
364 "term \"%s\", cmd \"%s\", env %u", __func__, c->self,
365 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
366 cctx->want_subsys, cctx->term, cmd, env_len);
367
368 buffer_init(&cctx->cmd);
369 buffer_append(&cctx->cmd, cmd, strlen(cmd));
370 xfree(cmd);
371 cmd = NULL;
372
373 /* Gather fds from client */
374 for(i = 0; i < 3; i++) {
375 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
376 error("%s: failed to receive fd %d from slave",
377 __func__, i);
378 for (j = 0; j < i; j++)
379 close(new_fd[j]);
380 for (j = 0; j < env_len; j++)
381 xfree(cctx->env[j]);
382 if (env_len > 0)
383 xfree(cctx->env);
384 xfree(cctx->term);
385 buffer_free(&cctx->cmd);
386 xfree(cctx);
387
388 /* prepare reply */
389 buffer_put_int(r, MUX_S_FAILURE);
390 buffer_put_int(r, rid);
391 buffer_put_cstring(r,
392 "did not receive file descriptors");
393 return -1;
394 }
395 }
396
397 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
398 new_fd[0], new_fd[1], new_fd[2]);
399
400 /* XXX support multiple child sessions in future */
401 if (c->remote_id != -1) {
402 debug2("%s: session already open", __func__);
403 /* prepare reply */
404 buffer_put_int(r, MUX_S_FAILURE);
405 buffer_put_int(r, rid);
406 buffer_put_cstring(r, "Multiple sessions not supported");
407 cleanup:
408 close(new_fd[0]);
409 close(new_fd[1]);
410 close(new_fd[2]);
411 xfree(cctx->term);
412 if (env_len != 0) {
413 for (i = 0; i < env_len; i++)
414 xfree(cctx->env[i]);
415 xfree(cctx->env);
416 }
417 buffer_free(&cctx->cmd);
418 return 0;
419 }
420
421 if (options.control_master == SSHCTL_MASTER_ASK ||
422 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
423 if (!ask_permission("Allow shared connection to %s? ", host)) {
424 debug2("%s: session refused by user", __func__);
425 /* prepare reply */
426 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
427 buffer_put_int(r, rid);
428 buffer_put_cstring(r, "Permission denied");
429 goto cleanup;
430 }
431 }
432
433 /* Try to pick up ttymodes from client before it goes raw */
434 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
435 error("%s: tcgetattr: %s", __func__, strerror(errno));
436
437 /* enable nonblocking unless tty */
438 if (!isatty(new_fd[0]))
439 set_nonblock(new_fd[0]);
440 if (!isatty(new_fd[1]))
441 set_nonblock(new_fd[1]);
442 if (!isatty(new_fd[2]))
443 set_nonblock(new_fd[2]);
444
445 window = CHAN_SES_WINDOW_DEFAULT;
446 packetmax = CHAN_SES_PACKET_DEFAULT;
447 if (cctx->want_tty) {
448 window >>= 1;
449 packetmax >>= 1;
450 }
451
452 nc = channel_new("session", SSH_CHANNEL_OPENING,
453 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
454 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
455
456 nc->ctl_chan = c->self; /* link session -> control channel */
457 c->remote_id = nc->self; /* link control -> session channel */
458
459 if (cctx->want_tty && escape_char != 0xffffffff) {
460 channel_register_filter(nc->self,
461 client_simple_escape_filter, NULL,
462 client_filter_cleanup,
463 client_new_escape_filter_ctx((int)escape_char));
464 }
465
466 debug2("%s: channel_new: %d linked to control channel %d",
467 __func__, nc->self, nc->ctl_chan);
468
469 channel_send_open(nc->self);
470 channel_register_open_confirm(nc->self, mux_session_confirm, cctx);
471 c->mux_pause = 1; /* stop handling messages until open_confirm done */
472 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
473
474 /* reply is deferred, sent by mux_session_confirm */
475 return 0;
476 }
477
478 static int
process_mux_alive_check(u_int rid,Channel * c,Buffer * m,Buffer * r)479 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r)
480 {
481 debug2("%s: channel %d: alive check", __func__, c->self);
482
483 /* prepare reply */
484 buffer_put_int(r, MUX_S_ALIVE);
485 buffer_put_int(r, rid);
486 buffer_put_int(r, (u_int)getpid());
487
488 return 0;
489 }
490
491 static int
process_mux_terminate(u_int rid,Channel * c,Buffer * m,Buffer * r)492 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r)
493 {
494 debug2("%s: channel %d: terminate request", __func__, c->self);
495
496 if (options.control_master == SSHCTL_MASTER_ASK ||
497 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
498 if (!ask_permission("Terminate shared connection to %s? ",
499 host)) {
500 debug2("%s: termination refused by user", __func__);
501 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
502 buffer_put_int(r, rid);
503 buffer_put_cstring(r, "Permission denied");
504 return 0;
505 }
506 }
507
508 quit_pending = 1;
509 buffer_put_int(r, MUX_S_OK);
510 buffer_put_int(r, rid);
511 /* XXX exit happens too soon - message never makes it to client */
512 return 0;
513 }
514
515 static char *
format_forward(u_int ftype,Forward * fwd)516 format_forward(u_int ftype, Forward *fwd)
517 {
518 char *ret;
519
520 switch (ftype) {
521 case MUX_FWD_LOCAL:
522 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
523 (fwd->listen_host == NULL) ?
524 (options.gateway_ports ? "*" : "LOCALHOST") :
525 fwd->listen_host, fwd->listen_port,
526 fwd->connect_host, fwd->connect_port);
527 break;
528 case MUX_FWD_DYNAMIC:
529 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
530 (fwd->listen_host == NULL) ?
531 (options.gateway_ports ? "*" : "LOCALHOST") :
532 fwd->listen_host, fwd->listen_port);
533 break;
534 case MUX_FWD_REMOTE:
535 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
536 (fwd->listen_host == NULL) ?
537 "LOCALHOST" : fwd->listen_host,
538 fwd->listen_port,
539 fwd->connect_host, fwd->connect_port);
540 break;
541 default:
542 fatal("%s: unknown forward type %u", __func__, ftype);
543 }
544 return ret;
545 }
546
547 static int
compare_host(const char * a,const char * b)548 compare_host(const char *a, const char *b)
549 {
550 if (a == NULL && b == NULL)
551 return 1;
552 if (a == NULL || b == NULL)
553 return 0;
554 return strcmp(a, b) == 0;
555 }
556
557 static int
compare_forward(Forward * a,Forward * b)558 compare_forward(Forward *a, Forward *b)
559 {
560 if (!compare_host(a->listen_host, b->listen_host))
561 return 0;
562 if (a->listen_port != b->listen_port)
563 return 0;
564 if (!compare_host(a->connect_host, b->connect_host))
565 return 0;
566 if (a->connect_port != b->connect_port)
567 return 0;
568
569 return 1;
570 }
571
572 static void
mux_confirm_remote_forward(int type,u_int32_t seq,void * ctxt)573 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
574 {
575 struct mux_channel_confirm_ctx *fctx = ctxt;
576 char *failmsg = NULL;
577 Forward *rfwd;
578 Channel *c;
579 Buffer out;
580
581 if ((c = channel_by_id(fctx->cid)) == NULL) {
582 /* no channel for reply */
583 error("%s: unknown channel", __func__);
584 return;
585 }
586 buffer_init(&out);
587 if (fctx->fid >= options.num_remote_forwards) {
588 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
589 goto fail;
590 }
591 rfwd = &options.remote_forwards[fctx->fid];
592 debug("%s: %s for: listen %d, connect %s:%d", __func__,
593 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
594 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
595 if (type == SSH2_MSG_REQUEST_SUCCESS) {
596 if (rfwd->listen_port == 0) {
597 rfwd->allocated_port = packet_get_int();
598 logit("Allocated port %u for mux remote forward"
599 " to %s:%d", rfwd->allocated_port,
600 rfwd->connect_host, rfwd->connect_port);
601 buffer_put_int(&out, MUX_S_REMOTE_PORT);
602 buffer_put_int(&out, fctx->rid);
603 buffer_put_int(&out, rfwd->allocated_port);
604 } else {
605 buffer_put_int(&out, MUX_S_OK);
606 buffer_put_int(&out, fctx->rid);
607 }
608 goto out;
609 } else {
610 xasprintf(&failmsg, "remote port forwarding failed for "
611 "listen port %d", rfwd->listen_port);
612 }
613 fail:
614 error("%s: %s", __func__, failmsg);
615 buffer_put_int(&out, MUX_S_FAILURE);
616 buffer_put_int(&out, fctx->rid);
617 buffer_put_cstring(&out, failmsg);
618 xfree(failmsg);
619 out:
620 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out));
621 buffer_free(&out);
622 if (c->mux_pause <= 0)
623 fatal("%s: mux_pause %d", __func__, c->mux_pause);
624 c->mux_pause = 0; /* start processing messages again */
625 }
626
627 static int
process_mux_open_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)628 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
629 {
630 Forward fwd;
631 char *fwd_desc = NULL;
632 u_int ftype;
633 int i, ret = 0, freefwd = 1;
634
635 fwd.listen_host = fwd.connect_host = NULL;
636 if (buffer_get_int_ret(&ftype, m) != 0 ||
637 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL ||
638 buffer_get_int_ret(&fwd.listen_port, m) != 0 ||
639 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
640 buffer_get_int_ret(&fwd.connect_port, m) != 0) {
641 error("%s: malformed message", __func__);
642 ret = -1;
643 goto out;
644 }
645
646 if (*fwd.listen_host == '\0') {
647 xfree(fwd.listen_host);
648 fwd.listen_host = NULL;
649 }
650 if (*fwd.connect_host == '\0') {
651 xfree(fwd.connect_host);
652 fwd.connect_host = NULL;
653 }
654
655 debug2("%s: channel %d: request %s", __func__, c->self,
656 (fwd_desc = format_forward(ftype, &fwd)));
657
658 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
659 ftype != MUX_FWD_DYNAMIC) {
660 logit("%s: invalid forwarding type %u", __func__, ftype);
661 invalid:
662 if (fwd.listen_host)
663 xfree(fwd.listen_host);
664 if (fwd.connect_host)
665 xfree(fwd.connect_host);
666 buffer_put_int(r, MUX_S_FAILURE);
667 buffer_put_int(r, rid);
668 buffer_put_cstring(r, "Invalid forwarding request");
669 return 0;
670 }
671 if (fwd.listen_port >= 65536) {
672 logit("%s: invalid listen port %u", __func__,
673 fwd.listen_port);
674 goto invalid;
675 }
676 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC &&
677 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) {
678 logit("%s: invalid connect port %u", __func__,
679 fwd.connect_port);
680 goto invalid;
681 }
682 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) {
683 logit("%s: missing connect host", __func__);
684 goto invalid;
685 }
686
687 /* Skip forwards that have already been requested */
688 switch (ftype) {
689 case MUX_FWD_LOCAL:
690 case MUX_FWD_DYNAMIC:
691 for (i = 0; i < options.num_local_forwards; i++) {
692 if (compare_forward(&fwd,
693 options.local_forwards + i)) {
694 exists:
695 debug2("%s: found existing forwarding",
696 __func__);
697 buffer_put_int(r, MUX_S_OK);
698 buffer_put_int(r, rid);
699 goto out;
700 }
701 }
702 break;
703 case MUX_FWD_REMOTE:
704 for (i = 0; i < options.num_remote_forwards; i++) {
705 if (compare_forward(&fwd,
706 options.remote_forwards + i)) {
707 if (fwd.listen_port != 0)
708 goto exists;
709 debug2("%s: found allocated port",
710 __func__);
711 buffer_put_int(r, MUX_S_REMOTE_PORT);
712 buffer_put_int(r, rid);
713 buffer_put_int(r,
714 options.remote_forwards[i].allocated_port);
715 goto out;
716 }
717 }
718 break;
719 }
720
721 if (options.control_master == SSHCTL_MASTER_ASK ||
722 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
723 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
724 debug2("%s: forwarding refused by user", __func__);
725 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
726 buffer_put_int(r, rid);
727 buffer_put_cstring(r, "Permission denied");
728 goto out;
729 }
730 }
731
732 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
733 if (channel_setup_local_fwd_listener(fwd.listen_host,
734 fwd.listen_port, fwd.connect_host, fwd.connect_port,
735 options.gateway_ports) < 0) {
736 fail:
737 logit("slave-requested %s failed", fwd_desc);
738 buffer_put_int(r, MUX_S_FAILURE);
739 buffer_put_int(r, rid);
740 buffer_put_cstring(r, "Port forwarding failed");
741 goto out;
742 }
743 add_local_forward(&options, &fwd);
744 freefwd = 0;
745 } else {
746 struct mux_channel_confirm_ctx *fctx;
747
748 if (channel_request_remote_forwarding(fwd.listen_host,
749 fwd.listen_port, fwd.connect_host, fwd.connect_port) < 0)
750 goto fail;
751 add_remote_forward(&options, &fwd);
752 fctx = xcalloc(1, sizeof(*fctx));
753 fctx->cid = c->self;
754 fctx->rid = rid;
755 fctx->fid = options.num_remote_forwards - 1;
756 client_register_global_confirm(mux_confirm_remote_forward,
757 fctx);
758 freefwd = 0;
759 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
760 /* delayed reply in mux_confirm_remote_forward */
761 goto out;
762 }
763 buffer_put_int(r, MUX_S_OK);
764 buffer_put_int(r, rid);
765 out:
766 if (fwd_desc != NULL)
767 xfree(fwd_desc);
768 if (freefwd) {
769 if (fwd.listen_host != NULL)
770 xfree(fwd.listen_host);
771 if (fwd.connect_host != NULL)
772 xfree(fwd.connect_host);
773 }
774 return ret;
775 }
776
777 static int
process_mux_close_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)778 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
779 {
780 Forward fwd;
781 char *fwd_desc = NULL;
782 u_int ftype;
783 int ret = 0;
784
785 fwd.listen_host = fwd.connect_host = NULL;
786 if (buffer_get_int_ret(&ftype, m) != 0 ||
787 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL ||
788 buffer_get_int_ret(&fwd.listen_port, m) != 0 ||
789 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
790 buffer_get_int_ret(&fwd.connect_port, m) != 0) {
791 error("%s: malformed message", __func__);
792 ret = -1;
793 goto out;
794 }
795
796 if (*fwd.listen_host == '\0') {
797 xfree(fwd.listen_host);
798 fwd.listen_host = NULL;
799 }
800 if (*fwd.connect_host == '\0') {
801 xfree(fwd.connect_host);
802 fwd.connect_host = NULL;
803 }
804
805 debug2("%s: channel %d: request %s", __func__, c->self,
806 (fwd_desc = format_forward(ftype, &fwd)));
807
808 /* XXX implement this */
809 buffer_put_int(r, MUX_S_FAILURE);
810 buffer_put_int(r, rid);
811 buffer_put_cstring(r, "unimplemented");
812
813 out:
814 if (fwd_desc != NULL)
815 xfree(fwd_desc);
816 if (fwd.listen_host != NULL)
817 xfree(fwd.listen_host);
818 if (fwd.connect_host != NULL)
819 xfree(fwd.connect_host);
820
821 return ret;
822 }
823
824 static int
process_mux_stdio_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)825 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
826 {
827 Channel *nc;
828 char *reserved, *chost;
829 u_int cport, i, j;
830 int new_fd[2];
831
832 chost = reserved = NULL;
833 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
834 (chost = buffer_get_string_ret(m, NULL)) == NULL ||
835 buffer_get_int_ret(&cport, m) != 0) {
836 if (reserved != NULL)
837 xfree(reserved);
838 if (chost != NULL)
839 xfree(chost);
840 error("%s: malformed message", __func__);
841 return -1;
842 }
843 xfree(reserved);
844
845 debug2("%s: channel %d: request stdio fwd to %s:%u",
846 __func__, c->self, chost, cport);
847
848 /* Gather fds from client */
849 for(i = 0; i < 2; i++) {
850 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
851 error("%s: failed to receive fd %d from slave",
852 __func__, i);
853 for (j = 0; j < i; j++)
854 close(new_fd[j]);
855 xfree(chost);
856
857 /* prepare reply */
858 buffer_put_int(r, MUX_S_FAILURE);
859 buffer_put_int(r, rid);
860 buffer_put_cstring(r,
861 "did not receive file descriptors");
862 return -1;
863 }
864 }
865
866 debug3("%s: got fds stdin %d, stdout %d", __func__,
867 new_fd[0], new_fd[1]);
868
869 /* XXX support multiple child sessions in future */
870 if (c->remote_id != -1) {
871 debug2("%s: session already open", __func__);
872 /* prepare reply */
873 buffer_put_int(r, MUX_S_FAILURE);
874 buffer_put_int(r, rid);
875 buffer_put_cstring(r, "Multiple sessions not supported");
876 cleanup:
877 close(new_fd[0]);
878 close(new_fd[1]);
879 xfree(chost);
880 return 0;
881 }
882
883 if (options.control_master == SSHCTL_MASTER_ASK ||
884 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
885 if (!ask_permission("Allow forward to %s:%u? ",
886 chost, cport)) {
887 debug2("%s: stdio fwd refused by user", __func__);
888 /* prepare reply */
889 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
890 buffer_put_int(r, rid);
891 buffer_put_cstring(r, "Permission denied");
892 goto cleanup;
893 }
894 }
895
896 /* enable nonblocking unless tty */
897 if (!isatty(new_fd[0]))
898 set_nonblock(new_fd[0]);
899 if (!isatty(new_fd[1]))
900 set_nonblock(new_fd[1]);
901
902 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]);
903
904 nc->ctl_chan = c->self; /* link session -> control channel */
905 c->remote_id = nc->self; /* link control -> session channel */
906
907 debug2("%s: channel_new: %d linked to control channel %d",
908 __func__, nc->self, nc->ctl_chan);
909
910 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
911
912 /* prepare reply */
913 /* XXX defer until channel confirmed */
914 buffer_put_int(r, MUX_S_SESSION_OPENED);
915 buffer_put_int(r, rid);
916 buffer_put_int(r, nc->self);
917
918 return 0;
919 }
920
921 static int
process_mux_stop_listening(u_int rid,Channel * c,Buffer * m,Buffer * r)922 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
923 {
924 debug("%s: channel %d: stop listening", __func__, c->self);
925
926 if (options.control_master == SSHCTL_MASTER_ASK ||
927 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
928 if (!ask_permission("Disable further multiplexing on shared "
929 "connection to %s? ", host)) {
930 debug2("%s: stop listen refused by user", __func__);
931 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
932 buffer_put_int(r, rid);
933 buffer_put_cstring(r, "Permission denied");
934 return 0;
935 }
936 }
937
938 if (mux_listener_channel != NULL) {
939 channel_free(mux_listener_channel);
940 client_stop_mux();
941 xfree(options.control_path);
942 options.control_path = NULL;
943 mux_listener_channel = NULL;
944 muxserver_sock = -1;
945 }
946
947 /* prepare reply */
948 buffer_put_int(r, MUX_S_OK);
949 buffer_put_int(r, rid);
950
951 return 0;
952 }
953
954 /* Channel callbacks fired on read/write from mux slave fd */
955 static int
mux_master_read_cb(Channel * c)956 mux_master_read_cb(Channel *c)
957 {
958 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
959 Buffer in, out;
960 void *ptr;
961 u_int type, rid, have, i;
962 int ret = -1;
963
964 /* Setup ctx and */
965 if (c->mux_ctx == NULL) {
966 state = xcalloc(1, sizeof(*state));
967 c->mux_ctx = state;
968 channel_register_cleanup(c->self,
969 mux_master_control_cleanup_cb, 0);
970
971 /* Send hello */
972 buffer_init(&out);
973 buffer_put_int(&out, MUX_MSG_HELLO);
974 buffer_put_int(&out, SSHMUX_VER);
975 /* no extensions */
976 buffer_put_string(&c->output, buffer_ptr(&out),
977 buffer_len(&out));
978 buffer_free(&out);
979 debug3("%s: channel %d: hello sent", __func__, c->self);
980 return 0;
981 }
982
983 buffer_init(&in);
984 buffer_init(&out);
985
986 /* Channel code ensures that we receive whole packets */
987 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) {
988 malf:
989 error("%s: malformed message", __func__);
990 goto out;
991 }
992 buffer_append(&in, ptr, have);
993
994 if (buffer_get_int_ret(&type, &in) != 0)
995 goto malf;
996 debug3("%s: channel %d packet type 0x%08x len %u",
997 __func__, c->self, type, buffer_len(&in));
998
999 if (type == MUX_MSG_HELLO)
1000 rid = 0;
1001 else {
1002 if (!state->hello_rcvd) {
1003 error("%s: expected MUX_MSG_HELLO(0x%08x), "
1004 "received 0x%08x", __func__, MUX_MSG_HELLO, type);
1005 goto out;
1006 }
1007 if (buffer_get_int_ret(&rid, &in) != 0)
1008 goto malf;
1009 }
1010
1011 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
1012 if (type == mux_master_handlers[i].type) {
1013 ret = mux_master_handlers[i].handler(rid, c, &in, &out);
1014 break;
1015 }
1016 }
1017 if (mux_master_handlers[i].handler == NULL) {
1018 error("%s: unsupported mux message 0x%08x", __func__, type);
1019 buffer_put_int(&out, MUX_S_FAILURE);
1020 buffer_put_int(&out, rid);
1021 buffer_put_cstring(&out, "unsupported request");
1022 ret = 0;
1023 }
1024 /* Enqueue reply packet */
1025 if (buffer_len(&out) != 0) {
1026 buffer_put_string(&c->output, buffer_ptr(&out),
1027 buffer_len(&out));
1028 }
1029 out:
1030 buffer_free(&in);
1031 buffer_free(&out);
1032 return ret;
1033 }
1034
1035 void
mux_exit_message(Channel * c,int exitval)1036 mux_exit_message(Channel *c, int exitval)
1037 {
1038 Buffer m;
1039 Channel *mux_chan;
1040
1041 debug3("%s: channel %d: exit message, evitval %d", __func__, c->self,
1042 exitval);
1043
1044 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
1045 fatal("%s: channel %d missing mux channel %d",
1046 __func__, c->self, c->ctl_chan);
1047
1048 /* Append exit message packet to control socket output queue */
1049 buffer_init(&m);
1050 buffer_put_int(&m, MUX_S_EXIT_MESSAGE);
1051 buffer_put_int(&m, c->self);
1052 buffer_put_int(&m, exitval);
1053
1054 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
1055 buffer_free(&m);
1056 }
1057
1058 void
mux_tty_alloc_failed(Channel * c)1059 mux_tty_alloc_failed(Channel *c)
1060 {
1061 Buffer m;
1062 Channel *mux_chan;
1063
1064 debug3("%s: channel %d: TTY alloc failed", __func__, c->self);
1065
1066 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
1067 fatal("%s: channel %d missing mux channel %d",
1068 __func__, c->self, c->ctl_chan);
1069
1070 /* Append exit message packet to control socket output queue */
1071 buffer_init(&m);
1072 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL);
1073 buffer_put_int(&m, c->self);
1074
1075 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
1076 buffer_free(&m);
1077 }
1078
1079 /* Prepare a mux master to listen on a Unix domain socket. */
1080 void
muxserver_listen(void)1081 muxserver_listen(void)
1082 {
1083 struct sockaddr_un addr;
1084 socklen_t sun_len;
1085 mode_t old_umask;
1086 char *orig_control_path = options.control_path;
1087 char rbuf[16+1];
1088 u_int i, r;
1089
1090 if (options.control_path == NULL ||
1091 options.control_master == SSHCTL_MASTER_NO)
1092 return;
1093
1094 debug("setting up multiplex master socket");
1095
1096 /*
1097 * Use a temporary path before listen so we can pseudo-atomically
1098 * establish the listening socket in its final location to avoid
1099 * other processes racing in between bind() and listen() and hitting
1100 * an unready socket.
1101 */
1102 for (i = 0; i < sizeof(rbuf) - 1; i++) {
1103 r = arc4random_uniform(26+26+10);
1104 rbuf[i] = (r < 26) ? 'a' + r :
1105 (r < 26*2) ? 'A' + r - 26 :
1106 '0' + r - 26 - 26;
1107 }
1108 rbuf[sizeof(rbuf) - 1] = '\0';
1109 options.control_path = NULL;
1110 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
1111 debug3("%s: temporary control path %s", __func__, options.control_path);
1112
1113 memset(&addr, '\0', sizeof(addr));
1114 addr.sun_family = AF_UNIX;
1115 sun_len = offsetof(struct sockaddr_un, sun_path) +
1116 strlen(options.control_path) + 1;
1117
1118 if (strlcpy(addr.sun_path, options.control_path,
1119 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) {
1120 error("ControlPath \"%s\" too long for Unix domain socket",
1121 options.control_path);
1122 goto disable_mux_master;
1123 }
1124
1125 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1126 fatal("%s socket(): %s", __func__, strerror(errno));
1127
1128 old_umask = umask(0177);
1129 if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) {
1130 if (errno == EINVAL || errno == EADDRINUSE) {
1131 error("ControlSocket %s already exists, "
1132 "disabling multiplexing", options.control_path);
1133 disable_mux_master:
1134 if (muxserver_sock != -1) {
1135 close(muxserver_sock);
1136 muxserver_sock = -1;
1137 }
1138 xfree(options.control_path);
1139 options.control_path = NULL;
1140 options.control_master = SSHCTL_MASTER_NO;
1141 return;
1142 } else
1143 fatal("%s bind(): %s", __func__, strerror(errno));
1144 }
1145 umask(old_umask);
1146
1147 if (listen(muxserver_sock, 64) == -1)
1148 fatal("%s listen(): %s", __func__, strerror(errno));
1149
1150 /* Now atomically "move" the mux socket into position */
1151 if (link(options.control_path, orig_control_path) != 0) {
1152 if (errno != EEXIST) {
1153 fatal("%s: link mux listener %s => %s: %s", __func__,
1154 options.control_path, orig_control_path,
1155 strerror(errno));
1156 }
1157 error("ControlSocket %s already exists, disabling multiplexing",
1158 orig_control_path);
1159 xfree(orig_control_path);
1160 unlink(options.control_path);
1161 goto disable_mux_master;
1162 }
1163 unlink(options.control_path);
1164 xfree(options.control_path);
1165 options.control_path = orig_control_path;
1166
1167 set_nonblock(muxserver_sock);
1168
1169 mux_listener_channel = channel_new("mux listener",
1170 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
1171 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1172 0, options.control_path, 1);
1173 mux_listener_channel->mux_rcb = mux_master_read_cb;
1174 debug3("%s: mux listener channel %d fd %d", __func__,
1175 mux_listener_channel->self, mux_listener_channel->sock);
1176 }
1177
1178 /* Callback on open confirmation in mux master for a mux client session. */
1179 static void
mux_session_confirm(int id,int success,void * arg)1180 mux_session_confirm(int id, int success, void *arg)
1181 {
1182 struct mux_session_confirm_ctx *cctx = arg;
1183 const char *display;
1184 Channel *c, *cc;
1185 int i;
1186 Buffer reply;
1187
1188 if (cctx == NULL)
1189 fatal("%s: cctx == NULL", __func__);
1190 if ((c = channel_by_id(id)) == NULL)
1191 fatal("%s: no channel for id %d", __func__, id);
1192 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
1193 fatal("%s: channel %d lacks control channel %d", __func__,
1194 id, c->ctl_chan);
1195
1196 if (!success) {
1197 debug3("%s: sending failure reply", __func__);
1198 /* prepare reply */
1199 buffer_init(&reply);
1200 buffer_put_int(&reply, MUX_S_FAILURE);
1201 buffer_put_int(&reply, cctx->rid);
1202 buffer_put_cstring(&reply, "Session open refused by peer");
1203 goto done;
1204 }
1205
1206 display = getenv("DISPLAY");
1207 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1208 char *proto, *data;
1209
1210 /* Get reasonable local authentication information. */
1211 client_x11_get_proto(display, options.xauth_location,
1212 options.forward_x11_trusted, options.forward_x11_timeout,
1213 &proto, &data);
1214 /* Request forwarding with authentication spoofing. */
1215 debug("Requesting X11 forwarding with authentication "
1216 "spoofing.");
1217 x11_request_forwarding_with_spoofing(id, display, proto,
1218 data, 1);
1219 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1220 /* XXX exit_on_forward_failure */
1221 }
1222
1223 if (cctx->want_agent_fwd && options.forward_agent) {
1224 debug("Requesting authentication agent forwarding.");
1225 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1226 packet_send();
1227 }
1228
1229 client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
1230 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
1231
1232 debug3("%s: sending success reply", __func__);
1233 /* prepare reply */
1234 buffer_init(&reply);
1235 buffer_put_int(&reply, MUX_S_SESSION_OPENED);
1236 buffer_put_int(&reply, cctx->rid);
1237 buffer_put_int(&reply, c->self);
1238
1239 done:
1240 /* Send reply */
1241 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
1242 buffer_free(&reply);
1243
1244 if (cc->mux_pause <= 0)
1245 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1246 cc->mux_pause = 0; /* start processing messages again */
1247 c->open_confirm_ctx = NULL;
1248 buffer_free(&cctx->cmd);
1249 xfree(cctx->term);
1250 if (cctx->env != NULL) {
1251 for (i = 0; cctx->env[i] != NULL; i++)
1252 xfree(cctx->env[i]);
1253 xfree(cctx->env);
1254 }
1255 xfree(cctx);
1256 }
1257
1258 /* ** Multiplexing client support */
1259
1260 /* Exit signal handler */
1261 static void
control_client_sighandler(int signo)1262 control_client_sighandler(int signo)
1263 {
1264 muxclient_terminate = signo;
1265 }
1266
1267 /*
1268 * Relay signal handler - used to pass some signals from mux client to
1269 * mux master.
1270 */
1271 static void
control_client_sigrelay(int signo)1272 control_client_sigrelay(int signo)
1273 {
1274 int save_errno = errno;
1275
1276 if (muxserver_pid > 1)
1277 kill(muxserver_pid, signo);
1278
1279 errno = save_errno;
1280 }
1281
1282 static int
mux_client_read(int fd,Buffer * b,u_int need)1283 mux_client_read(int fd, Buffer *b, u_int need)
1284 {
1285 u_int have;
1286 ssize_t len;
1287 u_char *p;
1288 struct pollfd pfd;
1289
1290 pfd.fd = fd;
1291 pfd.events = POLLIN;
1292 p = buffer_append_space(b, need);
1293 for (have = 0; have < need; ) {
1294 if (muxclient_terminate) {
1295 errno = EINTR;
1296 return -1;
1297 }
1298 len = read(fd, p + have, need - have);
1299 if (len < 0) {
1300 switch (errno) {
1301 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1302 case EWOULDBLOCK:
1303 #endif
1304 case EAGAIN:
1305 (void)poll(&pfd, 1, -1);
1306 /* FALLTHROUGH */
1307 case EINTR:
1308 continue;
1309 default:
1310 return -1;
1311 }
1312 }
1313 if (len == 0) {
1314 errno = EPIPE;
1315 return -1;
1316 }
1317 have += (u_int)len;
1318 }
1319 return 0;
1320 }
1321
1322 static int
mux_client_write_packet(int fd,Buffer * m)1323 mux_client_write_packet(int fd, Buffer *m)
1324 {
1325 Buffer queue;
1326 u_int have, need;
1327 int oerrno, len;
1328 u_char *ptr;
1329 struct pollfd pfd;
1330
1331 pfd.fd = fd;
1332 pfd.events = POLLOUT;
1333 buffer_init(&queue);
1334 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m));
1335
1336 need = buffer_len(&queue);
1337 ptr = buffer_ptr(&queue);
1338
1339 for (have = 0; have < need; ) {
1340 if (muxclient_terminate) {
1341 buffer_free(&queue);
1342 errno = EINTR;
1343 return -1;
1344 }
1345 len = write(fd, ptr + have, need - have);
1346 if (len < 0) {
1347 switch (errno) {
1348 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1349 case EWOULDBLOCK:
1350 #endif
1351 case EAGAIN:
1352 (void)poll(&pfd, 1, -1);
1353 /* FALLTHROUGH */
1354 case EINTR:
1355 continue;
1356 default:
1357 oerrno = errno;
1358 buffer_free(&queue);
1359 errno = oerrno;
1360 return -1;
1361 }
1362 }
1363 if (len == 0) {
1364 buffer_free(&queue);
1365 errno = EPIPE;
1366 return -1;
1367 }
1368 have += (u_int)len;
1369 }
1370 buffer_free(&queue);
1371 return 0;
1372 }
1373
1374 static int
mux_client_read_packet(int fd,Buffer * m)1375 mux_client_read_packet(int fd, Buffer *m)
1376 {
1377 Buffer queue;
1378 u_int need, have;
1379 void *ptr;
1380 int oerrno;
1381
1382 buffer_init(&queue);
1383 if (mux_client_read(fd, &queue, 4) != 0) {
1384 if ((oerrno = errno) == EPIPE)
1385 debug3("%s: read header failed: %s", __func__, strerror(errno));
1386 errno = oerrno;
1387 return -1;
1388 }
1389 need = get_u32(buffer_ptr(&queue));
1390 if (mux_client_read(fd, &queue, need) != 0) {
1391 oerrno = errno;
1392 debug3("%s: read body failed: %s", __func__, strerror(errno));
1393 errno = oerrno;
1394 return -1;
1395 }
1396 ptr = buffer_get_string_ptr(&queue, &have);
1397 buffer_append(m, ptr, have);
1398 buffer_free(&queue);
1399 return 0;
1400 }
1401
1402 static int
mux_client_hello_exchange(int fd)1403 mux_client_hello_exchange(int fd)
1404 {
1405 Buffer m;
1406 u_int type, ver;
1407
1408 buffer_init(&m);
1409 buffer_put_int(&m, MUX_MSG_HELLO);
1410 buffer_put_int(&m, SSHMUX_VER);
1411 /* no extensions */
1412
1413 if (mux_client_write_packet(fd, &m) != 0)
1414 fatal("%s: write packet: %s", __func__, strerror(errno));
1415
1416 buffer_clear(&m);
1417
1418 /* Read their HELLO */
1419 if (mux_client_read_packet(fd, &m) != 0) {
1420 buffer_free(&m);
1421 return -1;
1422 }
1423
1424 type = buffer_get_int(&m);
1425 if (type != MUX_MSG_HELLO)
1426 fatal("%s: expected HELLO (%u) received %u",
1427 __func__, MUX_MSG_HELLO, type);
1428 ver = buffer_get_int(&m);
1429 if (ver != SSHMUX_VER)
1430 fatal("Unsupported multiplexing protocol version %d "
1431 "(expected %d)", ver, SSHMUX_VER);
1432 debug2("%s: master version %u", __func__, ver);
1433 /* No extensions are presently defined */
1434 while (buffer_len(&m) > 0) {
1435 char *name = buffer_get_string(&m, NULL);
1436 char *value = buffer_get_string(&m, NULL);
1437
1438 debug2("Unrecognised master extension \"%s\"", name);
1439 xfree(name);
1440 xfree(value);
1441 }
1442 buffer_free(&m);
1443 return 0;
1444 }
1445
1446 static u_int
mux_client_request_alive(int fd)1447 mux_client_request_alive(int fd)
1448 {
1449 Buffer m;
1450 char *e;
1451 u_int pid, type, rid;
1452
1453 debug3("%s: entering", __func__);
1454
1455 buffer_init(&m);
1456 buffer_put_int(&m, MUX_C_ALIVE_CHECK);
1457 buffer_put_int(&m, muxclient_request_id);
1458
1459 if (mux_client_write_packet(fd, &m) != 0)
1460 fatal("%s: write packet: %s", __func__, strerror(errno));
1461
1462 buffer_clear(&m);
1463
1464 /* Read their reply */
1465 if (mux_client_read_packet(fd, &m) != 0) {
1466 buffer_free(&m);
1467 return 0;
1468 }
1469
1470 type = buffer_get_int(&m);
1471 if (type != MUX_S_ALIVE) {
1472 e = buffer_get_string(&m, NULL);
1473 fatal("%s: master returned error: %s", __func__, e);
1474 }
1475
1476 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1477 fatal("%s: out of sequence reply: my id %u theirs %u",
1478 __func__, muxclient_request_id, rid);
1479 pid = buffer_get_int(&m);
1480 buffer_free(&m);
1481
1482 debug3("%s: done pid = %u", __func__, pid);
1483
1484 muxclient_request_id++;
1485
1486 return pid;
1487 }
1488
1489 static void
mux_client_request_terminate(int fd)1490 mux_client_request_terminate(int fd)
1491 {
1492 Buffer m;
1493 char *e;
1494 u_int type, rid;
1495
1496 debug3("%s: entering", __func__);
1497
1498 buffer_init(&m);
1499 buffer_put_int(&m, MUX_C_TERMINATE);
1500 buffer_put_int(&m, muxclient_request_id);
1501
1502 if (mux_client_write_packet(fd, &m) != 0)
1503 fatal("%s: write packet: %s", __func__, strerror(errno));
1504
1505 buffer_clear(&m);
1506
1507 /* Read their reply */
1508 if (mux_client_read_packet(fd, &m) != 0) {
1509 /* Remote end exited already */
1510 if (errno == EPIPE) {
1511 buffer_free(&m);
1512 return;
1513 }
1514 fatal("%s: read from master failed: %s",
1515 __func__, strerror(errno));
1516 }
1517
1518 type = buffer_get_int(&m);
1519 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1520 fatal("%s: out of sequence reply: my id %u theirs %u",
1521 __func__, muxclient_request_id, rid);
1522 switch (type) {
1523 case MUX_S_OK:
1524 break;
1525 case MUX_S_PERMISSION_DENIED:
1526 e = buffer_get_string(&m, NULL);
1527 fatal("Master refused termination request: %s", e);
1528 case MUX_S_FAILURE:
1529 e = buffer_get_string(&m, NULL);
1530 fatal("%s: termination request failed: %s", __func__, e);
1531 default:
1532 fatal("%s: unexpected response from master 0x%08x",
1533 __func__, type);
1534 }
1535 buffer_free(&m);
1536 muxclient_request_id++;
1537 }
1538
1539 static int
mux_client_request_forward(int fd,u_int ftype,Forward * fwd)1540 mux_client_request_forward(int fd, u_int ftype, Forward *fwd)
1541 {
1542 Buffer m;
1543 char *e, *fwd_desc;
1544 u_int type, rid;
1545
1546 fwd_desc = format_forward(ftype, fwd);
1547 debug("Requesting %s", fwd_desc);
1548 xfree(fwd_desc);
1549
1550 buffer_init(&m);
1551 buffer_put_int(&m, MUX_C_OPEN_FWD);
1552 buffer_put_int(&m, muxclient_request_id);
1553 buffer_put_int(&m, ftype);
1554 buffer_put_cstring(&m,
1555 fwd->listen_host == NULL ? "" : fwd->listen_host);
1556 buffer_put_int(&m, fwd->listen_port);
1557 buffer_put_cstring(&m,
1558 fwd->connect_host == NULL ? "" : fwd->connect_host);
1559 buffer_put_int(&m, fwd->connect_port);
1560
1561 if (mux_client_write_packet(fd, &m) != 0)
1562 fatal("%s: write packet: %s", __func__, strerror(errno));
1563
1564 buffer_clear(&m);
1565
1566 /* Read their reply */
1567 if (mux_client_read_packet(fd, &m) != 0) {
1568 buffer_free(&m);
1569 return -1;
1570 }
1571
1572 type = buffer_get_int(&m);
1573 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1574 fatal("%s: out of sequence reply: my id %u theirs %u",
1575 __func__, muxclient_request_id, rid);
1576 switch (type) {
1577 case MUX_S_OK:
1578 break;
1579 case MUX_S_REMOTE_PORT:
1580 fwd->allocated_port = buffer_get_int(&m);
1581 logit("Allocated port %u for remote forward to %s:%d",
1582 fwd->allocated_port,
1583 fwd->connect_host ? fwd->connect_host : "",
1584 fwd->connect_port);
1585 if (muxclient_command == SSHMUX_COMMAND_FORWARD)
1586 fprintf(stdout, "%u\n", fwd->allocated_port);
1587 break;
1588 case MUX_S_PERMISSION_DENIED:
1589 e = buffer_get_string(&m, NULL);
1590 buffer_free(&m);
1591 error("Master refused forwarding request: %s", e);
1592 return -1;
1593 case MUX_S_FAILURE:
1594 e = buffer_get_string(&m, NULL);
1595 buffer_free(&m);
1596 error("%s: forwarding request failed: %s", __func__, e);
1597 return -1;
1598 default:
1599 fatal("%s: unexpected response from master 0x%08x",
1600 __func__, type);
1601 }
1602 buffer_free(&m);
1603
1604 muxclient_request_id++;
1605 return 0;
1606 }
1607
1608 static int
mux_client_request_forwards(int fd)1609 mux_client_request_forwards(int fd)
1610 {
1611 int i;
1612
1613 debug3("%s: requesting forwardings: %d local, %d remote", __func__,
1614 options.num_local_forwards, options.num_remote_forwards);
1615
1616 /* XXX ExitOnForwardingFailure */
1617 for (i = 0; i < options.num_local_forwards; i++) {
1618 if (mux_client_request_forward(fd,
1619 options.local_forwards[i].connect_port == 0 ?
1620 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1621 options.local_forwards + i) != 0)
1622 return -1;
1623 }
1624 for (i = 0; i < options.num_remote_forwards; i++) {
1625 if (mux_client_request_forward(fd, MUX_FWD_REMOTE,
1626 options.remote_forwards + i) != 0)
1627 return -1;
1628 }
1629 return 0;
1630 }
1631
1632 static int
mux_client_request_session(int fd)1633 mux_client_request_session(int fd)
1634 {
1635 Buffer m;
1636 char *e, *term;
1637 u_int i, rid, sid, esid, exitval, type, exitval_seen;
1638 extern char **environ;
1639 int devnull, rawmode;
1640
1641 debug3("%s: entering", __func__);
1642
1643 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1644 error("%s: master alive request failed", __func__);
1645 return -1;
1646 }
1647
1648 signal(SIGPIPE, SIG_IGN);
1649
1650 if (stdin_null_flag) {
1651 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1652 fatal("open(/dev/null): %s", strerror(errno));
1653 if (dup2(devnull, STDIN_FILENO) == -1)
1654 fatal("dup2: %s", strerror(errno));
1655 if (devnull > STDERR_FILENO)
1656 close(devnull);
1657 }
1658
1659 term = getenv("TERM");
1660
1661 buffer_init(&m);
1662 buffer_put_int(&m, MUX_C_NEW_SESSION);
1663 buffer_put_int(&m, muxclient_request_id);
1664 buffer_put_cstring(&m, ""); /* reserved */
1665 buffer_put_int(&m, tty_flag);
1666 buffer_put_int(&m, options.forward_x11);
1667 buffer_put_int(&m, options.forward_agent);
1668 buffer_put_int(&m, subsystem_flag);
1669 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ?
1670 0xffffffff : (u_int)options.escape_char);
1671 buffer_put_cstring(&m, term == NULL ? "" : term);
1672 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command));
1673
1674 if (options.num_send_env > 0 && environ != NULL) {
1675 /* Pass environment */
1676 for (i = 0; environ[i] != NULL; i++) {
1677 if (env_permitted(environ[i])) {
1678 buffer_put_cstring(&m, environ[i]);
1679 }
1680 }
1681 }
1682
1683 if (mux_client_write_packet(fd, &m) != 0)
1684 fatal("%s: write packet: %s", __func__, strerror(errno));
1685
1686 /* Send the stdio file descriptors */
1687 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1688 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1689 mm_send_fd(fd, STDERR_FILENO) == -1)
1690 fatal("%s: send fds failed", __func__);
1691
1692 debug3("%s: session request sent", __func__);
1693
1694 /* Read their reply */
1695 buffer_clear(&m);
1696 if (mux_client_read_packet(fd, &m) != 0) {
1697 error("%s: read from master failed: %s",
1698 __func__, strerror(errno));
1699 buffer_free(&m);
1700 return -1;
1701 }
1702
1703 type = buffer_get_int(&m);
1704 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1705 fatal("%s: out of sequence reply: my id %u theirs %u",
1706 __func__, muxclient_request_id, rid);
1707 switch (type) {
1708 case MUX_S_SESSION_OPENED:
1709 sid = buffer_get_int(&m);
1710 debug("%s: master session id: %u", __func__, sid);
1711 break;
1712 case MUX_S_PERMISSION_DENIED:
1713 e = buffer_get_string(&m, NULL);
1714 buffer_free(&m);
1715 error("Master refused session request: %s", e);
1716 return -1;
1717 case MUX_S_FAILURE:
1718 e = buffer_get_string(&m, NULL);
1719 buffer_free(&m);
1720 error("%s: session request failed: %s", __func__, e);
1721 return -1;
1722 default:
1723 buffer_free(&m);
1724 error("%s: unexpected response from master 0x%08x",
1725 __func__, type);
1726 return -1;
1727 }
1728 muxclient_request_id++;
1729
1730 signal(SIGHUP, control_client_sighandler);
1731 signal(SIGINT, control_client_sighandler);
1732 signal(SIGTERM, control_client_sighandler);
1733 signal(SIGWINCH, control_client_sigrelay);
1734
1735 rawmode = tty_flag;
1736 if (tty_flag)
1737 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1738
1739 /*
1740 * Stick around until the controlee closes the client_fd.
1741 * Before it does, it is expected to write an exit message.
1742 * This process must read the value and wait for the closure of
1743 * the client_fd; if this one closes early, the multiplex master will
1744 * terminate early too (possibly losing data).
1745 */
1746 for (exitval = 255, exitval_seen = 0;;) {
1747 buffer_clear(&m);
1748 if (mux_client_read_packet(fd, &m) != 0)
1749 break;
1750 type = buffer_get_int(&m);
1751 switch (type) {
1752 case MUX_S_TTY_ALLOC_FAIL:
1753 if ((esid = buffer_get_int(&m)) != sid)
1754 fatal("%s: tty alloc fail on unknown session: "
1755 "my id %u theirs %u",
1756 __func__, sid, esid);
1757 leave_raw_mode(options.request_tty ==
1758 REQUEST_TTY_FORCE);
1759 rawmode = 0;
1760 continue;
1761 case MUX_S_EXIT_MESSAGE:
1762 if ((esid = buffer_get_int(&m)) != sid)
1763 fatal("%s: exit on unknown session: "
1764 "my id %u theirs %u",
1765 __func__, sid, esid);
1766 if (exitval_seen)
1767 fatal("%s: exitval sent twice", __func__);
1768 exitval = buffer_get_int(&m);
1769 exitval_seen = 1;
1770 continue;
1771 default:
1772 e = buffer_get_string(&m, NULL);
1773 fatal("%s: master returned error: %s", __func__, e);
1774 }
1775 }
1776
1777 close(fd);
1778 if (rawmode)
1779 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1780
1781 if (muxclient_terminate) {
1782 debug2("Exiting on signal %d", muxclient_terminate);
1783 exitval = 255;
1784 } else if (!exitval_seen) {
1785 debug2("Control master terminated unexpectedly");
1786 exitval = 255;
1787 } else
1788 debug2("Received exit status from master %d", exitval);
1789
1790 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1791 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
1792
1793 exit(exitval);
1794 }
1795
1796 static int
mux_client_request_stdio_fwd(int fd)1797 mux_client_request_stdio_fwd(int fd)
1798 {
1799 Buffer m;
1800 char *e;
1801 u_int type, rid, sid;
1802 int devnull;
1803
1804 debug3("%s: entering", __func__);
1805
1806 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1807 error("%s: master alive request failed", __func__);
1808 return -1;
1809 }
1810
1811 signal(SIGPIPE, SIG_IGN);
1812
1813 if (stdin_null_flag) {
1814 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1815 fatal("open(/dev/null): %s", strerror(errno));
1816 if (dup2(devnull, STDIN_FILENO) == -1)
1817 fatal("dup2: %s", strerror(errno));
1818 if (devnull > STDERR_FILENO)
1819 close(devnull);
1820 }
1821
1822 buffer_init(&m);
1823 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD);
1824 buffer_put_int(&m, muxclient_request_id);
1825 buffer_put_cstring(&m, ""); /* reserved */
1826 buffer_put_cstring(&m, stdio_forward_host);
1827 buffer_put_int(&m, stdio_forward_port);
1828
1829 if (mux_client_write_packet(fd, &m) != 0)
1830 fatal("%s: write packet: %s", __func__, strerror(errno));
1831
1832 /* Send the stdio file descriptors */
1833 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1834 mm_send_fd(fd, STDOUT_FILENO) == -1)
1835 fatal("%s: send fds failed", __func__);
1836
1837 debug3("%s: stdio forward request sent", __func__);
1838
1839 /* Read their reply */
1840 buffer_clear(&m);
1841
1842 if (mux_client_read_packet(fd, &m) != 0) {
1843 error("%s: read from master failed: %s",
1844 __func__, strerror(errno));
1845 buffer_free(&m);
1846 return -1;
1847 }
1848
1849 type = buffer_get_int(&m);
1850 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1851 fatal("%s: out of sequence reply: my id %u theirs %u",
1852 __func__, muxclient_request_id, rid);
1853 switch (type) {
1854 case MUX_S_SESSION_OPENED:
1855 sid = buffer_get_int(&m);
1856 debug("%s: master session id: %u", __func__, sid);
1857 break;
1858 case MUX_S_PERMISSION_DENIED:
1859 e = buffer_get_string(&m, NULL);
1860 buffer_free(&m);
1861 fatal("Master refused stdio forwarding request: %s", e);
1862 case MUX_S_FAILURE:
1863 e = buffer_get_string(&m, NULL);
1864 buffer_free(&m);
1865 fatal("%s: stdio forwarding request failed: %s", __func__, e);
1866 default:
1867 buffer_free(&m);
1868 error("%s: unexpected response from master 0x%08x",
1869 __func__, type);
1870 return -1;
1871 }
1872 muxclient_request_id++;
1873
1874 signal(SIGHUP, control_client_sighandler);
1875 signal(SIGINT, control_client_sighandler);
1876 signal(SIGTERM, control_client_sighandler);
1877 signal(SIGWINCH, control_client_sigrelay);
1878
1879 /*
1880 * Stick around until the controlee closes the client_fd.
1881 */
1882 buffer_clear(&m);
1883 if (mux_client_read_packet(fd, &m) != 0) {
1884 if (errno == EPIPE ||
1885 (errno == EINTR && muxclient_terminate != 0))
1886 return 0;
1887 fatal("%s: mux_client_read_packet: %s",
1888 __func__, strerror(errno));
1889 }
1890 fatal("%s: master returned unexpected message %u", __func__, type);
1891 }
1892
1893 static void
mux_client_request_stop_listening(int fd)1894 mux_client_request_stop_listening(int fd)
1895 {
1896 Buffer m;
1897 char *e;
1898 u_int type, rid;
1899
1900 debug3("%s: entering", __func__);
1901
1902 buffer_init(&m);
1903 buffer_put_int(&m, MUX_C_STOP_LISTENING);
1904 buffer_put_int(&m, muxclient_request_id);
1905
1906 if (mux_client_write_packet(fd, &m) != 0)
1907 fatal("%s: write packet: %s", __func__, strerror(errno));
1908
1909 buffer_clear(&m);
1910
1911 /* Read their reply */
1912 if (mux_client_read_packet(fd, &m) != 0)
1913 fatal("%s: read from master failed: %s",
1914 __func__, strerror(errno));
1915
1916 type = buffer_get_int(&m);
1917 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1918 fatal("%s: out of sequence reply: my id %u theirs %u",
1919 __func__, muxclient_request_id, rid);
1920 switch (type) {
1921 case MUX_S_OK:
1922 break;
1923 case MUX_S_PERMISSION_DENIED:
1924 e = buffer_get_string(&m, NULL);
1925 fatal("Master refused stop listening request: %s", e);
1926 case MUX_S_FAILURE:
1927 e = buffer_get_string(&m, NULL);
1928 fatal("%s: stop listening request failed: %s", __func__, e);
1929 default:
1930 fatal("%s: unexpected response from master 0x%08x",
1931 __func__, type);
1932 }
1933 buffer_free(&m);
1934 muxclient_request_id++;
1935 }
1936
1937 /* Multiplex client main loop. */
1938 void
muxclient(const char * path)1939 muxclient(const char *path)
1940 {
1941 struct sockaddr_un addr;
1942 socklen_t sun_len;
1943 int sock;
1944 u_int pid;
1945
1946 if (muxclient_command == 0) {
1947 if (stdio_forward_host != NULL)
1948 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
1949 else
1950 muxclient_command = SSHMUX_COMMAND_OPEN;
1951 }
1952
1953 switch (options.control_master) {
1954 case SSHCTL_MASTER_AUTO:
1955 case SSHCTL_MASTER_AUTO_ASK:
1956 debug("auto-mux: Trying existing master");
1957 /* FALLTHROUGH */
1958 case SSHCTL_MASTER_NO:
1959 break;
1960 default:
1961 return;
1962 }
1963
1964 memset(&addr, '\0', sizeof(addr));
1965 addr.sun_family = AF_UNIX;
1966 sun_len = offsetof(struct sockaddr_un, sun_path) +
1967 strlen(path) + 1;
1968
1969 if (strlcpy(addr.sun_path, path,
1970 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1971 fatal("ControlPath too long");
1972
1973 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1974 fatal("%s socket(): %s", __func__, strerror(errno));
1975
1976 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) {
1977 switch (muxclient_command) {
1978 case SSHMUX_COMMAND_OPEN:
1979 case SSHMUX_COMMAND_STDIO_FWD:
1980 break;
1981 default:
1982 fatal("Control socket connect(%.100s): %s", path,
1983 strerror(errno));
1984 }
1985 if (errno == ECONNREFUSED &&
1986 options.control_master != SSHCTL_MASTER_NO) {
1987 debug("Stale control socket %.100s, unlinking", path);
1988 unlink(path);
1989 } else if (errno == ENOENT) {
1990 debug("Control socket \"%.100s\" does not exist", path);
1991 } else {
1992 error("Control socket connect(%.100s): %s", path,
1993 strerror(errno));
1994 }
1995 close(sock);
1996 return;
1997 }
1998 set_nonblock(sock);
1999
2000 if (mux_client_hello_exchange(sock) != 0) {
2001 error("%s: master hello exchange failed", __func__);
2002 close(sock);
2003 return;
2004 }
2005
2006 switch (muxclient_command) {
2007 case SSHMUX_COMMAND_ALIVE_CHECK:
2008 if ((pid = mux_client_request_alive(sock)) == 0)
2009 fatal("%s: master alive check failed", __func__);
2010 fprintf(stderr, "Master running (pid=%d)\r\n", pid);
2011 exit(0);
2012 case SSHMUX_COMMAND_TERMINATE:
2013 mux_client_request_terminate(sock);
2014 fprintf(stderr, "Exit request sent.\r\n");
2015 exit(0);
2016 case SSHMUX_COMMAND_FORWARD:
2017 if (mux_client_request_forwards(sock) != 0)
2018 fatal("%s: master forward request failed", __func__);
2019 exit(0);
2020 case SSHMUX_COMMAND_OPEN:
2021 if (mux_client_request_forwards(sock) != 0) {
2022 error("%s: master forward request failed", __func__);
2023 return;
2024 }
2025 mux_client_request_session(sock);
2026 return;
2027 case SSHMUX_COMMAND_STDIO_FWD:
2028 mux_client_request_stdio_fwd(sock);
2029 exit(0);
2030 case SSHMUX_COMMAND_STOP:
2031 mux_client_request_stop_listening(sock);
2032 fprintf(stderr, "Stop listening request sent.\r\n");
2033 exit(0);
2034 default:
2035 fatal("unrecognised muxclient_command %d", muxclient_command);
2036 }
2037 }
2038