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- (djm) [channels.c] Check for EPFNOSUPPORT as a socket() errno; bz#1721
[openssh-git.git] / mux.c
blob825fb7a9a70d648333190ad5b4457888f5ef7832
1 /* $OpenBSD: mux.c,v 1.14 2010/01/30 02:54:53 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 "pathnames.h"
75 #include "misc.h"
76 #include "match.h"
77 #include "buffer.h"
78 #include "channels.h"
79 #include "msg.h"
80 #include "packet.h"
81 #include "monitor_fdpass.h"
82 #include "sshpty.h"
83 #include "key.h"
84 #include "readconf.h"
85 #include "clientloop.h"
86
87 /* from ssh.c */
88 extern int tty_flag;
89 extern int force_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 };
110
111 /* fd to control socket */
112 int muxserver_sock = -1;
113
114 /* client request id */
115 u_int muxclient_request_id = 0;
116
117 /* Multiplexing control command */
118 u_int muxclient_command = 0;
119
120 /* Set when signalled. */
121 static volatile sig_atomic_t muxclient_terminate = 0;
122
123 /* PID of multiplex server */
124 static u_int muxserver_pid = 0;
125
126 static Channel *mux_listener_channel = NULL;
127
128 struct mux_master_state {
129 int hello_rcvd;
130 };
131
132 /* mux protocol messages */
133 #define MUX_MSG_HELLO 0x00000001
134 #define MUX_C_NEW_SESSION 0x10000002
135 #define MUX_C_ALIVE_CHECK 0x10000004
136 #define MUX_C_TERMINATE 0x10000005
137 #define MUX_C_OPEN_FWD 0x10000006
138 #define MUX_C_CLOSE_FWD 0x10000007
139 #define MUX_C_NEW_STDIO_FWD 0x10000008
140 #define MUX_S_OK 0x80000001
141 #define MUX_S_PERMISSION_DENIED 0x80000002
142 #define MUX_S_FAILURE 0x80000003
143 #define MUX_S_EXIT_MESSAGE 0x80000004
144 #define MUX_S_ALIVE 0x80000005
145 #define MUX_S_SESSION_OPENED 0x80000006
146
147 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
148 #define MUX_FWD_LOCAL 1
149 #define MUX_FWD_REMOTE 2
150 #define MUX_FWD_DYNAMIC 3
151
152 static void mux_session_confirm(int, void *);
153
154 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *);
155 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *);
156 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *);
157 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *);
158 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *);
159 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *);
160 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *);
161
162 static const struct {
163 u_int type;
164 int (*handler)(u_int, Channel *, Buffer *, Buffer *);
165 } mux_master_handlers[] = {
166 { MUX_MSG_HELLO, process_mux_master_hello },
167 { MUX_C_NEW_SESSION, process_mux_new_session },
168 { MUX_C_ALIVE_CHECK, process_mux_alive_check },
169 { MUX_C_TERMINATE, process_mux_terminate },
170 { MUX_C_OPEN_FWD, process_mux_open_fwd },
171 { MUX_C_CLOSE_FWD, process_mux_close_fwd },
172 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd },
173 { 0, NULL }
174 };
175
176 /* Cleanup callback fired on closure of mux slave _session_ channel */
177 /* ARGSUSED */
178 static void
179 mux_master_session_cleanup_cb(int cid, void *unused)
180 {
181 Channel *cc, *c = channel_by_id(cid);
182
183 debug3("%s: entering for channel %d", __func__, cid);
184 if (c == NULL)
185 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
186 if (c->ctl_chan != -1) {
187 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
188 fatal("%s: channel %d missing control channel %d",
189 __func__, c->self, c->ctl_chan);
190 c->ctl_chan = -1;
191 cc->remote_id = -1;
192 chan_rcvd_oclose(cc);
193 }
194 channel_cancel_cleanup(c->self);
195 }
196
197 /* Cleanup callback fired on closure of mux slave _control_ channel */
198 /* ARGSUSED */
199 static void
200 mux_master_control_cleanup_cb(int cid, void *unused)
201 {
202 Channel *sc, *c = channel_by_id(cid);
203
204 debug3("%s: entering for channel %d", __func__, cid);
205 if (c == NULL)
206 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
207 if (c->remote_id != -1) {
208 if ((sc = channel_by_id(c->remote_id)) == NULL)
209 debug2("%s: channel %d n session channel %d",
210 __func__, c->self, c->remote_id);
211 c->remote_id = -1;
212 sc->ctl_chan = -1;
213 if (sc->type != SSH_CHANNEL_OPEN) {
214 debug2("%s: channel %d: not open", __func__, sc->self);
215 chan_mark_dead(sc);
216 } else {
217 if (sc->istate == CHAN_INPUT_OPEN)
218 chan_read_failed(sc);
219 if (sc->ostate == CHAN_OUTPUT_OPEN)
220 chan_write_failed(sc);
221 }
222 }
223 channel_cancel_cleanup(c->self);
224 }
225
226 /* Check mux client environment variables before passing them to mux master. */
227 static int
228 env_permitted(char *env)
229 {
230 int i, ret;
231 char name[1024], *cp;
232
233 if ((cp = strchr(env, '=')) == NULL || cp == env)
234 return 0;
235 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
236 if (ret <= 0 || (size_t)ret >= sizeof(name)) {
237 error("env_permitted: name '%.100s...' too long", env);
238 return 0;
239 }
240
241 for (i = 0; i < options.num_send_env; i++)
242 if (match_pattern(name, options.send_env[i]))
243 return 1;
244
245 return 0;
246 }
247
248 /* Mux master protocol message handlers */
249
250 static int
251 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r)
252 {
253 u_int ver;
254 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
255
256 if (state == NULL)
257 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self);
258 if (state->hello_rcvd) {
259 error("%s: HELLO received twice", __func__);
260 return -1;
261 }
262 if (buffer_get_int_ret(&ver, m) != 0) {
263 malf:
264 error("%s: malformed message", __func__);
265 return -1;
266 }
267 if (ver != SSHMUX_VER) {
268 error("Unsupported multiplexing protocol version %d "
269 "(expected %d)", ver, SSHMUX_VER);
270 return -1;
271 }
272 debug2("%s: channel %d slave version %u", __func__, c->self, ver);
273
274 /* No extensions are presently defined */
275 while (buffer_len(m) > 0) {
276 char *name = buffer_get_string_ret(m, NULL);
277 char *value = buffer_get_string_ret(m, NULL);
278
279 if (name == NULL || value == NULL) {
280 if (name != NULL)
281 xfree(name);
282 goto malf;
283 }
284 debug2("Unrecognised slave extension \"%s\"", name);
285 xfree(name);
286 xfree(value);
287 }
288 state->hello_rcvd = 1;
289 return 0;
290 }
291
292 static int
293 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
294 {
295 Channel *nc;
296 struct mux_session_confirm_ctx *cctx;
297 char *reserved, *cmd, *cp;
298 u_int i, j, len, env_len, escape_char, window, packetmax;
299 int new_fd[3];
300
301 /* Reply for SSHMUX_COMMAND_OPEN */
302 cctx = xcalloc(1, sizeof(*cctx));
303 cctx->term = NULL;
304 cmd = reserved = NULL;
305 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
306 buffer_get_int_ret(&cctx->want_tty, m) != 0 ||
307 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 ||
308 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 ||
309 buffer_get_int_ret(&cctx->want_subsys, m) != 0 ||
310 buffer_get_int_ret(&escape_char, m) != 0 ||
311 (cctx->term = buffer_get_string_ret(m, &len)) == NULL ||
312 (cmd = buffer_get_string_ret(m, &len)) == NULL) {
313 malf:
314 if (cmd != NULL)
315 xfree(cmd);
316 if (reserved != NULL)
317 xfree(reserved);
318 if (cctx->term != NULL)
319 xfree(cctx->term);
320 error("%s: malformed message", __func__);
321 return -1;
322 }
323 xfree(reserved);
324 reserved = NULL;
325
326 cctx->env = NULL;
327 env_len = 0;
328 while (buffer_len(m) > 0) {
329 #define MUX_MAX_ENV_VARS 4096
330 if ((cp = buffer_get_string_ret(m, &len)) == NULL) {
331 xfree(cmd);
332 goto malf;
333 }
334 if (!env_permitted(cp)) {
335 xfree(cp);
336 continue;
337 }
338 cctx->env = xrealloc(cctx->env, env_len + 2,
339 sizeof(*cctx->env));
340 cctx->env[env_len++] = cp;
341 cctx->env[env_len] = NULL;
342 if (env_len > MUX_MAX_ENV_VARS) {
343 error(">%d environment variables received, ignoring "
344 "additional", MUX_MAX_ENV_VARS);
345 break;
346 }
347 }
348
349 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, "
350 "term \"%s\", cmd \"%s\", env %u", __func__, c->self,
351 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
352 cctx->want_subsys, cctx->term, cmd, env_len);
353
354 buffer_init(&cctx->cmd);
355 buffer_append(&cctx->cmd, cmd, strlen(cmd));
356 xfree(cmd);
357 cmd = NULL;
358
359 /* Gather fds from client */
360 for(i = 0; i < 3; i++) {
361 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
362 error("%s: failed to receive fd %d from slave",
363 __func__, i);
364 for (j = 0; j < i; j++)
365 close(new_fd[j]);
366 for (j = 0; j < env_len; j++)
367 xfree(cctx->env[j]);
368 if (env_len > 0)
369 xfree(cctx->env);
370 xfree(cctx->term);
371 buffer_free(&cctx->cmd);
372 xfree(cctx);
373
374 /* prepare reply */
375 buffer_put_int(r, MUX_S_FAILURE);
376 buffer_put_int(r, rid);
377 buffer_put_cstring(r,
378 "did not receive file descriptors");
379 return -1;
380 }
381 }
382
383 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
384 new_fd[0], new_fd[1], new_fd[2]);
385
386 /* XXX support multiple child sessions in future */
387 if (c->remote_id != -1) {
388 debug2("%s: session already open", __func__);
389 /* prepare reply */
390 buffer_put_int(r, MUX_S_FAILURE);
391 buffer_put_int(r, rid);
392 buffer_put_cstring(r, "Multiple sessions not supported");
393 cleanup:
394 close(new_fd[0]);
395 close(new_fd[1]);
396 close(new_fd[2]);
397 xfree(cctx->term);
398 if (env_len != 0) {
399 for (i = 0; i < env_len; i++)
400 xfree(cctx->env[i]);
401 xfree(cctx->env);
402 }
403 buffer_free(&cctx->cmd);
404 return 0;
405 }
406
407 if (options.control_master == SSHCTL_MASTER_ASK ||
408 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
409 if (!ask_permission("Allow shared connection to %s? ", host)) {
410 debug2("%s: session refused by user", __func__);
411 /* prepare reply */
412 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
413 buffer_put_int(r, rid);
414 buffer_put_cstring(r, "Permission denied");
415 goto cleanup;
416 }
417 }
418
419 /* Try to pick up ttymodes from client before it goes raw */
420 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
421 error("%s: tcgetattr: %s", __func__, strerror(errno));
422
423 /* enable nonblocking unless tty */
424 if (!isatty(new_fd[0]))
425 set_nonblock(new_fd[0]);
426 if (!isatty(new_fd[1]))
427 set_nonblock(new_fd[1]);
428 if (!isatty(new_fd[2]))
429 set_nonblock(new_fd[2]);
430
431 window = CHAN_SES_WINDOW_DEFAULT;
432 packetmax = CHAN_SES_PACKET_DEFAULT;
433 if (cctx->want_tty) {
434 window >>= 1;
435 packetmax >>= 1;
436 }
437
438 nc = channel_new("session", SSH_CHANNEL_OPENING,
439 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
440 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
441
442 nc->ctl_chan = c->self; /* link session -> control channel */
443 c->remote_id = nc->self; /* link control -> session channel */
444
445 if (cctx->want_tty && escape_char != 0xffffffff) {
446 channel_register_filter(nc->self,
447 client_simple_escape_filter, NULL,
448 client_filter_cleanup,
449 client_new_escape_filter_ctx((int)escape_char));
450 }
451
452 debug2("%s: channel_new: %d linked to control channel %d",
453 __func__, nc->self, nc->ctl_chan);
454
455 channel_send_open(nc->self);
456 channel_register_open_confirm(nc->self, mux_session_confirm, cctx);
457 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 0);
458
459 /* prepare reply */
460 /* XXX defer until mux_session_confirm() fires */
461 buffer_put_int(r, MUX_S_SESSION_OPENED);
462 buffer_put_int(r, rid);
463 buffer_put_int(r, nc->self);
464
465 return 0;
466 }
467
468 static int
469 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r)
470 {
471 debug2("%s: channel %d: alive check", __func__, c->self);
472
473 /* prepare reply */
474 buffer_put_int(r, MUX_S_ALIVE);
475 buffer_put_int(r, rid);
476 buffer_put_int(r, (u_int)getpid());
477
478 return 0;
479 }
480
481 static int
482 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r)
483 {
484 debug2("%s: channel %d: terminate request", __func__, c->self);
485
486 if (options.control_master == SSHCTL_MASTER_ASK ||
487 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
488 if (!ask_permission("Terminate shared connection to %s? ",
489 host)) {
490 debug2("%s: termination refused by user", __func__);
491 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
492 buffer_put_int(r, rid);
493 buffer_put_cstring(r, "Permission denied");
494 return 0;
495 }
496 }
497
498 quit_pending = 1;
499 buffer_put_int(r, MUX_S_OK);
500 buffer_put_int(r, rid);
501 /* XXX exit happens too soon - message never makes it to client */
502 return 0;
503 }
504
505 static char *
506 format_forward(u_int ftype, Forward *fwd)
507 {
508 char *ret;
509
510 switch (ftype) {
511 case MUX_FWD_LOCAL:
512 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
513 (fwd->listen_host == NULL) ?
514 (options.gateway_ports ? "*" : "LOCALHOST") :
515 fwd->listen_host, fwd->listen_port,
516 fwd->connect_host, fwd->connect_port);
517 break;
518 case MUX_FWD_DYNAMIC:
519 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
520 (fwd->listen_host == NULL) ?
521 (options.gateway_ports ? "*" : "LOCALHOST") :
522 fwd->listen_host, fwd->listen_port);
523 break;
524 case MUX_FWD_REMOTE:
525 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
526 (fwd->listen_host == NULL) ?
527 "LOCALHOST" : fwd->listen_host,
528 fwd->listen_port,
529 fwd->connect_host, fwd->connect_port);
530 break;
531 default:
532 fatal("%s: unknown forward type %u", __func__, ftype);
533 }
534 return ret;
535 }
536
537 static int
538 compare_host(const char *a, const char *b)
539 {
540 if (a == NULL && b == NULL)
541 return 1;
542 if (a == NULL || b == NULL)
543 return 0;
544 return strcmp(a, b) == 0;
545 }
546
547 static int
548 compare_forward(Forward *a, Forward *b)
549 {
550 if (!compare_host(a->listen_host, b->listen_host))
551 return 0;
552 if (a->listen_port != b->listen_port)
553 return 0;
554 if (!compare_host(a->connect_host, b->connect_host))
555 return 0;
556 if (a->connect_port != b->connect_port)
557 return 0;
558
559 return 1;
560 }
561
562 static int
563 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
564 {
565 Forward fwd;
566 char *fwd_desc = NULL;
567 u_int ftype;
568 int i, ret = 0, freefwd = 1;
569
570 fwd.listen_host = fwd.connect_host = NULL;
571 if (buffer_get_int_ret(&ftype, m) != 0 ||
572 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL ||
573 buffer_get_int_ret(&fwd.listen_port, m) != 0 ||
574 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
575 buffer_get_int_ret(&fwd.connect_port, m) != 0) {
576 error("%s: malformed message", __func__);
577 ret = -1;
578 goto out;
579 }
580
581 if (*fwd.listen_host == '\0') {
582 xfree(fwd.listen_host);
583 fwd.listen_host = NULL;
584 }
585 if (*fwd.connect_host == '\0') {
586 xfree(fwd.connect_host);
587 fwd.connect_host = NULL;
588 }
589
590 debug2("%s: channel %d: request %s", __func__, c->self,
591 (fwd_desc = format_forward(ftype, &fwd)));
592
593 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
594 ftype != MUX_FWD_DYNAMIC) {
595 logit("%s: invalid forwarding type %u", __func__, ftype);
596 invalid:
597 xfree(fwd.listen_host);
598 xfree(fwd.connect_host);
599 buffer_put_int(r, MUX_S_FAILURE);
600 buffer_put_int(r, rid);
601 buffer_put_cstring(r, "Invalid forwarding request");
602 return 0;
603 }
604 /* XXX support rport0 forwarding with reply of port assigned */
605 if (fwd.listen_port == 0 || fwd.listen_port >= 65536) {
606 logit("%s: invalid listen port %u", __func__,
607 fwd.listen_port);
608 goto invalid;
609 }
610 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC &&
611 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) {
612 logit("%s: invalid connect port %u", __func__,
613 fwd.connect_port);
614 goto invalid;
615 }
616 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) {
617 logit("%s: missing connect host", __func__);
618 goto invalid;
619 }
620
621 /* Skip forwards that have already been requested */
622 switch (ftype) {
623 case MUX_FWD_LOCAL:
624 case MUX_FWD_DYNAMIC:
625 for (i = 0; i < options.num_local_forwards; i++) {
626 if (compare_forward(&fwd,
627 options.local_forwards + i)) {
628 exists:
629 debug2("%s: found existing forwarding",
630 __func__);
631 buffer_put_int(r, MUX_S_OK);
632 buffer_put_int(r, rid);
633 goto out;
634 }
635 }
636 break;
637 case MUX_FWD_REMOTE:
638 for (i = 0; i < options.num_remote_forwards; i++) {
639 if (compare_forward(&fwd,
640 options.remote_forwards + i))
641 goto exists;
642 }
643 break;
644 }
645
646 if (options.control_master == SSHCTL_MASTER_ASK ||
647 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
648 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
649 debug2("%s: forwarding refused by user", __func__);
650 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
651 buffer_put_int(r, rid);
652 buffer_put_cstring(r, "Permission denied");
653 goto out;
654 }
655 }
656
657 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
658 if (options.num_local_forwards + 1 >=
659 SSH_MAX_FORWARDS_PER_DIRECTION ||
660 channel_setup_local_fwd_listener(fwd.listen_host,
661 fwd.listen_port, fwd.connect_host, fwd.connect_port,
662 options.gateway_ports) < 0) {
663 fail:
664 logit("slave-requested %s failed", fwd_desc);
665 buffer_put_int(r, MUX_S_FAILURE);
666 buffer_put_int(r, rid);
667 buffer_put_cstring(r, "Port forwarding failed");
668 goto out;
669 }
670 add_local_forward(&options, &fwd);
671 freefwd = 0;
672 } else {
673 /* XXX wait for remote to confirm */
674 if (options.num_remote_forwards + 1 >=
675 SSH_MAX_FORWARDS_PER_DIRECTION ||
676 channel_request_remote_forwarding(fwd.listen_host,
677 fwd.listen_port, fwd.connect_host, fwd.connect_port) < 0)
678 goto fail;
679 add_remote_forward(&options, &fwd);
680 freefwd = 0;
681 }
682 buffer_put_int(r, MUX_S_OK);
683 buffer_put_int(r, rid);
684 out:
685 if (fwd_desc != NULL)
686 xfree(fwd_desc);
687 if (freefwd) {
688 if (fwd.listen_host != NULL)
689 xfree(fwd.listen_host);
690 if (fwd.connect_host != NULL)
691 xfree(fwd.connect_host);
692 }
693 return ret;
694 }
695
696 static int
697 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
698 {
699 Forward fwd;
700 char *fwd_desc = NULL;
701 u_int ftype;
702 int ret = 0;
703
704 fwd.listen_host = fwd.connect_host = NULL;
705 if (buffer_get_int_ret(&ftype, m) != 0 ||
706 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL ||
707 buffer_get_int_ret(&fwd.listen_port, m) != 0 ||
708 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL ||
709 buffer_get_int_ret(&fwd.connect_port, m) != 0) {
710 error("%s: malformed message", __func__);
711 ret = -1;
712 goto out;
713 }
714
715 if (*fwd.listen_host == '\0') {
716 xfree(fwd.listen_host);
717 fwd.listen_host = NULL;
718 }
719 if (*fwd.connect_host == '\0') {
720 xfree(fwd.connect_host);
721 fwd.connect_host = NULL;
722 }
723
724 debug2("%s: channel %d: request %s", __func__, c->self,
725 (fwd_desc = format_forward(ftype, &fwd)));
726
727 /* XXX implement this */
728 buffer_put_int(r, MUX_S_FAILURE);
729 buffer_put_int(r, rid);
730 buffer_put_cstring(r, "unimplemented");
731
732 out:
733 if (fwd_desc != NULL)
734 xfree(fwd_desc);
735 if (fwd.listen_host != NULL)
736 xfree(fwd.listen_host);
737 if (fwd.connect_host != NULL)
738 xfree(fwd.connect_host);
739
740 return ret;
741 }
742
743 static int
744 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
745 {
746 Channel *nc;
747 char *reserved, *chost;
748 u_int cport, i, j;
749 int new_fd[2];
750
751 chost = reserved = NULL;
752 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
753 (chost = buffer_get_string_ret(m, NULL)) == NULL ||
754 buffer_get_int_ret(&cport, m) != 0) {
755 if (reserved != NULL)
756 xfree(reserved);
757 if (chost != NULL)
758 xfree(chost);
759 error("%s: malformed message", __func__);
760 return -1;
761 }
762 xfree(reserved);
763
764 debug2("%s: channel %d: request stdio fwd to %s:%u",
765 __func__, c->self, chost, cport);
766
767 /* Gather fds from client */
768 for(i = 0; i < 2; i++) {
769 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
770 error("%s: failed to receive fd %d from slave",
771 __func__, i);
772 for (j = 0; j < i; j++)
773 close(new_fd[j]);
774 xfree(chost);
775
776 /* prepare reply */
777 buffer_put_int(r, MUX_S_FAILURE);
778 buffer_put_int(r, rid);
779 buffer_put_cstring(r,
780 "did not receive file descriptors");
781 return -1;
782 }
783 }
784
785 debug3("%s: got fds stdin %d, stdout %d", __func__,
786 new_fd[0], new_fd[1]);
787
788 /* XXX support multiple child sessions in future */
789 if (c->remote_id != -1) {
790 debug2("%s: session already open", __func__);
791 /* prepare reply */
792 buffer_put_int(r, MUX_S_FAILURE);
793 buffer_put_int(r, rid);
794 buffer_put_cstring(r, "Multiple sessions not supported");
795 cleanup:
796 close(new_fd[0]);
797 close(new_fd[1]);
798 xfree(chost);
799 return 0;
800 }
801
802 if (options.control_master == SSHCTL_MASTER_ASK ||
803 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
804 if (!ask_permission("Allow forward to to %s:%u? ",
805 chost, cport)) {
806 debug2("%s: stdio fwd refused by user", __func__);
807 /* prepare reply */
808 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
809 buffer_put_int(r, rid);
810 buffer_put_cstring(r, "Permission denied");
811 goto cleanup;
812 }
813 }
814
815 /* enable nonblocking unless tty */
816 if (!isatty(new_fd[0]))
817 set_nonblock(new_fd[0]);
818 if (!isatty(new_fd[1]))
819 set_nonblock(new_fd[1]);
820
821 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]);
822
823 nc->ctl_chan = c->self; /* link session -> control channel */
824 c->remote_id = nc->self; /* link control -> session channel */
825
826 debug2("%s: channel_new: %d linked to control channel %d",
827 __func__, nc->self, nc->ctl_chan);
828
829 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 0);
830
831 /* prepare reply */
832 /* XXX defer until channel confirmed */
833 buffer_put_int(r, MUX_S_SESSION_OPENED);
834 buffer_put_int(r, rid);
835 buffer_put_int(r, nc->self);
836
837 return 0;
838 }
839
840 /* Channel callbacks fired on read/write from mux slave fd */
841 static int
842 mux_master_read_cb(Channel *c)
843 {
844 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
845 Buffer in, out;
846 void *ptr;
847 u_int type, rid, have, i;
848 int ret = -1;
849
850 /* Setup ctx and */
851 if (c->mux_ctx == NULL) {
852 state = xcalloc(1, sizeof(state));
853 c->mux_ctx = state;
854 channel_register_cleanup(c->self,
855 mux_master_control_cleanup_cb, 0);
856
857 /* Send hello */
858 buffer_init(&out);
859 buffer_put_int(&out, MUX_MSG_HELLO);
860 buffer_put_int(&out, SSHMUX_VER);
861 /* no extensions */
862 buffer_put_string(&c->output, buffer_ptr(&out),
863 buffer_len(&out));
864 buffer_free(&out);
865 debug3("%s: channel %d: hello sent", __func__, c->self);
866 return 0;
867 }
868
869 buffer_init(&in);
870 buffer_init(&out);
871
872 /* Channel code ensures that we receive whole packets */
873 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) {
874 malf:
875 error("%s: malformed message", __func__);
876 goto out;
877 }
878 buffer_append(&in, ptr, have);
879
880 if (buffer_get_int_ret(&type, &in) != 0)
881 goto malf;
882 debug3("%s: channel %d packet type 0x%08x len %u",
883 __func__, c->self, type, buffer_len(&in));
884
885 if (type == MUX_MSG_HELLO)
886 rid = 0;
887 else {
888 if (!state->hello_rcvd) {
889 error("%s: expected MUX_MSG_HELLO(0x%08x), "
890 "received 0x%08x", __func__, MUX_MSG_HELLO, type);
891 goto out;
892 }
893 if (buffer_get_int_ret(&rid, &in) != 0)
894 goto malf;
895 }
896
897 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
898 if (type == mux_master_handlers[i].type) {
899 ret = mux_master_handlers[i].handler(rid, c, &in, &out);
900 break;
901 }
902 }
903 if (mux_master_handlers[i].handler == NULL) {
904 error("%s: unsupported mux message 0x%08x", __func__, type);
905 buffer_put_int(&out, MUX_S_FAILURE);
906 buffer_put_int(&out, rid);
907 buffer_put_cstring(&out, "unsupported request");
908 ret = 0;
909 }
910 /* Enqueue reply packet */
911 if (buffer_len(&out) != 0) {
912 buffer_put_string(&c->output, buffer_ptr(&out),
913 buffer_len(&out));
914 }
915 out:
916 buffer_free(&in);
917 buffer_free(&out);
918 return ret;
919 }
920
921 void
922 mux_exit_message(Channel *c, int exitval)
923 {
924 Buffer m;
925 Channel *mux_chan;
926
927 debug3("%s: channel %d: exit message, evitval %d", __func__, c->self,
928 exitval);
929
930 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
931 fatal("%s: channel %d missing mux channel %d",
932 __func__, c->self, c->ctl_chan);
933
934 /* Append exit message packet to control socket output queue */
935 buffer_init(&m);
936 buffer_put_int(&m, MUX_S_EXIT_MESSAGE);
937 buffer_put_int(&m, c->self);
938 buffer_put_int(&m, exitval);
939
940 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
941 buffer_free(&m);
942 }
943
944 /* Prepare a mux master to listen on a Unix domain socket. */
945 void
946 muxserver_listen(void)
947 {
948 struct sockaddr_un addr;
949 socklen_t sun_len;
950 mode_t old_umask;
951
952 if (options.control_path == NULL ||
953 options.control_master == SSHCTL_MASTER_NO)
954 return;
955
956 debug("setting up multiplex master socket");
957
958 memset(&addr, '\0', sizeof(addr));
959 addr.sun_family = AF_UNIX;
960 sun_len = offsetof(struct sockaddr_un, sun_path) +
961 strlen(options.control_path) + 1;
962
963 if (strlcpy(addr.sun_path, options.control_path,
964 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
965 fatal("ControlPath too long");
966
967 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
968 fatal("%s socket(): %s", __func__, strerror(errno));
969
970 old_umask = umask(0177);
971 if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) {
972 muxserver_sock = -1;
973 if (errno == EINVAL || errno == EADDRINUSE) {
974 error("ControlSocket %s already exists, "
975 "disabling multiplexing", options.control_path);
976 close(muxserver_sock);
977 muxserver_sock = -1;
978 xfree(options.control_path);
979 options.control_path = NULL;
980 options.control_master = SSHCTL_MASTER_NO;
981 return;
982 } else
983 fatal("%s bind(): %s", __func__, strerror(errno));
984 }
985 umask(old_umask);
986
987 if (listen(muxserver_sock, 64) == -1)
988 fatal("%s listen(): %s", __func__, strerror(errno));
989
990 set_nonblock(muxserver_sock);
991
992 mux_listener_channel = channel_new("mux listener",
993 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
994 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
995 0, addr.sun_path, 1);
996 mux_listener_channel->mux_rcb = mux_master_read_cb;
997 debug3("%s: mux listener channel %d fd %d", __func__,
998 mux_listener_channel->self, mux_listener_channel->sock);
999 }
1000
1001 /* Callback on open confirmation in mux master for a mux client session. */
1002 static void
1003 mux_session_confirm(int id, void *arg)
1004 {
1005 struct mux_session_confirm_ctx *cctx = arg;
1006 const char *display;
1007 Channel *c;
1008 int i;
1009
1010 if (cctx == NULL)
1011 fatal("%s: cctx == NULL", __func__);
1012 if ((c = channel_by_id(id)) == NULL)
1013 fatal("%s: no channel for id %d", __func__, id);
1014
1015 display = getenv("DISPLAY");
1016 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1017 char *proto, *data;
1018 /* Get reasonable local authentication information. */
1019 client_x11_get_proto(display, options.xauth_location,
1020 options.forward_x11_trusted, &proto, &data);
1021 /* Request forwarding with authentication spoofing. */
1022 debug("Requesting X11 forwarding with authentication spoofing.");
1023 x11_request_forwarding_with_spoofing(id, display, proto, data);
1024 /* XXX wait for reply */
1025 }
1026
1027 if (cctx->want_agent_fwd && options.forward_agent) {
1028 debug("Requesting authentication agent forwarding.");
1029 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1030 packet_send();
1031 }
1032
1033 client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
1034 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
1035
1036 c->open_confirm_ctx = NULL;
1037 buffer_free(&cctx->cmd);
1038 xfree(cctx->term);
1039 if (cctx->env != NULL) {
1040 for (i = 0; cctx->env[i] != NULL; i++)
1041 xfree(cctx->env[i]);
1042 xfree(cctx->env);
1043 }
1044 xfree(cctx);
1045 }
1046
1047 /* ** Multiplexing client support */
1048
1049 /* Exit signal handler */
1050 static void
1051 control_client_sighandler(int signo)
1052 {
1053 muxclient_terminate = signo;
1054 }
1055
1056 /*
1057 * Relay signal handler - used to pass some signals from mux client to
1058 * mux master.
1059 */
1060 static void
1061 control_client_sigrelay(int signo)
1062 {
1063 int save_errno = errno;
1064
1065 if (muxserver_pid > 1)
1066 kill(muxserver_pid, signo);
1067
1068 errno = save_errno;
1069 }
1070
1071 static int
1072 mux_client_read(int fd, Buffer *b, u_int need)
1073 {
1074 u_int have;
1075 ssize_t len;
1076 u_char *p;
1077 struct pollfd pfd;
1078
1079 pfd.fd = fd;
1080 pfd.events = POLLIN;
1081 p = buffer_append_space(b, need);
1082 for (have = 0; have < need; ) {
1083 if (muxclient_terminate) {
1084 errno = EINTR;
1085 return -1;
1086 }
1087 len = read(fd, p + have, need - have);
1088 if (len < 0) {
1089 switch (errno) {
1090 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1091 case EWOULDBLOCK:
1092 #endif
1093 case EAGAIN:
1094 (void)poll(&pfd, 1, -1);
1095 /* FALLTHROUGH */
1096 case EINTR:
1097 continue;
1098 default:
1099 return -1;
1100 }
1101 }
1102 if (len == 0) {
1103 errno = EPIPE;
1104 return -1;
1105 }
1106 have += (u_int)len;
1107 }
1108 return 0;
1109 }
1110
1111 static int
1112 mux_client_write_packet(int fd, Buffer *m)
1113 {
1114 Buffer queue;
1115 u_int have, need;
1116 int oerrno, len;
1117 u_char *ptr;
1118 struct pollfd pfd;
1119
1120 pfd.fd = fd;
1121 pfd.events = POLLOUT;
1122 buffer_init(&queue);
1123 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m));
1124
1125 need = buffer_len(&queue);
1126 ptr = buffer_ptr(&queue);
1127
1128 for (have = 0; have < need; ) {
1129 if (muxclient_terminate) {
1130 buffer_free(&queue);
1131 errno = EINTR;
1132 return -1;
1133 }
1134 len = write(fd, ptr + have, need - have);
1135 if (len < 0) {
1136 switch (errno) {
1137 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1138 case EWOULDBLOCK:
1139 #endif
1140 case EAGAIN:
1141 (void)poll(&pfd, 1, -1);
1142 /* FALLTHROUGH */
1143 case EINTR:
1144 continue;
1145 default:
1146 oerrno = errno;
1147 buffer_free(&queue);
1148 errno = oerrno;
1149 return -1;
1150 }
1151 }
1152 if (len == 0) {
1153 buffer_free(&queue);
1154 errno = EPIPE;
1155 return -1;
1156 }
1157 have += (u_int)len;
1158 }
1159 buffer_free(&queue);
1160 return 0;
1161 }
1162
1163 static int
1164 mux_client_read_packet(int fd, Buffer *m)
1165 {
1166 Buffer queue;
1167 u_int need, have;
1168 void *ptr;
1169 int oerrno;
1170
1171 buffer_init(&queue);
1172 if (mux_client_read(fd, &queue, 4) != 0) {
1173 if ((oerrno = errno) == EPIPE)
1174 debug3("%s: read header failed: %s", __func__, strerror(errno));
1175 errno = oerrno;
1176 return -1;
1177 }
1178 need = get_u32(buffer_ptr(&queue));
1179 if (mux_client_read(fd, &queue, need) != 0) {
1180 oerrno = errno;
1181 debug3("%s: read body failed: %s", __func__, strerror(errno));
1182 errno = oerrno;
1183 return -1;
1184 }
1185 ptr = buffer_get_string_ptr(&queue, &have);
1186 buffer_append(m, ptr, have);
1187 buffer_free(&queue);
1188 return 0;
1189 }
1190
1191 static int
1192 mux_client_hello_exchange(int fd)
1193 {
1194 Buffer m;
1195 u_int type, ver;
1196
1197 buffer_init(&m);
1198 buffer_put_int(&m, MUX_MSG_HELLO);
1199 buffer_put_int(&m, SSHMUX_VER);
1200 /* no extensions */
1201
1202 if (mux_client_write_packet(fd, &m) != 0)
1203 fatal("%s: write packet: %s", __func__, strerror(errno));
1204
1205 buffer_clear(&m);
1206
1207 /* Read their HELLO */
1208 if (mux_client_read_packet(fd, &m) != 0) {
1209 buffer_free(&m);
1210 return -1;
1211 }
1212
1213 type = buffer_get_int(&m);
1214 if (type != MUX_MSG_HELLO)
1215 fatal("%s: expected HELLO (%u) received %u",
1216 __func__, MUX_MSG_HELLO, type);
1217 ver = buffer_get_int(&m);
1218 if (ver != SSHMUX_VER)
1219 fatal("Unsupported multiplexing protocol version %d "
1220 "(expected %d)", ver, SSHMUX_VER);
1221 debug2("%s: master version %u", __func__, ver);
1222 /* No extensions are presently defined */
1223 while (buffer_len(&m) > 0) {
1224 char *name = buffer_get_string(&m, NULL);
1225 char *value = buffer_get_string(&m, NULL);
1226
1227 debug2("Unrecognised master extension \"%s\"", name);
1228 xfree(name);
1229 xfree(value);
1230 }
1231 buffer_free(&m);
1232 return 0;
1233 }
1234
1235 static u_int
1236 mux_client_request_alive(int fd)
1237 {
1238 Buffer m;
1239 char *e;
1240 u_int pid, type, rid;
1241
1242 debug3("%s: entering", __func__);
1243
1244 buffer_init(&m);
1245 buffer_put_int(&m, MUX_C_ALIVE_CHECK);
1246 buffer_put_int(&m, muxclient_request_id);
1247
1248 if (mux_client_write_packet(fd, &m) != 0)
1249 fatal("%s: write packet: %s", __func__, strerror(errno));
1250
1251 buffer_clear(&m);
1252
1253 /* Read their reply */
1254 if (mux_client_read_packet(fd, &m) != 0) {
1255 buffer_free(&m);
1256 return 0;
1257 }
1258
1259 type = buffer_get_int(&m);
1260 if (type != MUX_S_ALIVE) {
1261 e = buffer_get_string(&m, NULL);
1262 fatal("%s: master returned error: %s", __func__, e);
1263 }
1264
1265 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1266 fatal("%s: out of sequence reply: my id %u theirs %u",
1267 __func__, muxclient_request_id, rid);
1268 pid = buffer_get_int(&m);
1269 buffer_free(&m);
1270
1271 debug3("%s: done pid = %u", __func__, pid);
1272
1273 muxclient_request_id++;
1274
1275 return pid;
1276 }
1277
1278 static void
1279 mux_client_request_terminate(int fd)
1280 {
1281 Buffer m;
1282 char *e;
1283 u_int type, rid;
1284
1285 debug3("%s: entering", __func__);
1286
1287 buffer_init(&m);
1288 buffer_put_int(&m, MUX_C_TERMINATE);
1289 buffer_put_int(&m, muxclient_request_id);
1290
1291 if (mux_client_write_packet(fd, &m) != 0)
1292 fatal("%s: write packet: %s", __func__, strerror(errno));
1293
1294 buffer_clear(&m);
1295
1296 /* Read their reply */
1297 if (mux_client_read_packet(fd, &m) != 0) {
1298 /* Remote end exited already */
1299 if (errno == EPIPE) {
1300 buffer_free(&m);
1301 return;
1302 }
1303 fatal("%s: read from master failed: %s",
1304 __func__, strerror(errno));
1305 }
1306
1307 type = buffer_get_int(&m);
1308 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1309 fatal("%s: out of sequence reply: my id %u theirs %u",
1310 __func__, muxclient_request_id, rid);
1311 switch (type) {
1312 case MUX_S_OK:
1313 break;
1314 case MUX_S_PERMISSION_DENIED:
1315 e = buffer_get_string(&m, NULL);
1316 fatal("Master refused termination request: %s", e);
1317 case MUX_S_FAILURE:
1318 e = buffer_get_string(&m, NULL);
1319 fatal("%s: termination request failed: %s", __func__, e);
1320 default:
1321 fatal("%s: unexpected response from master 0x%08x",
1322 __func__, type);
1323 }
1324 buffer_free(&m);
1325 muxclient_request_id++;
1326 }
1327
1328 static int
1329 mux_client_request_forward(int fd, u_int ftype, Forward *fwd)
1330 {
1331 Buffer m;
1332 char *e, *fwd_desc;
1333 u_int type, rid;
1334
1335 fwd_desc = format_forward(ftype, fwd);
1336 debug("Requesting %s", fwd_desc);
1337 xfree(fwd_desc);
1338
1339 buffer_init(&m);
1340 buffer_put_int(&m, MUX_C_OPEN_FWD);
1341 buffer_put_int(&m, muxclient_request_id);
1342 buffer_put_int(&m, ftype);
1343 buffer_put_cstring(&m,
1344 fwd->listen_host == NULL ? "" : fwd->listen_host);
1345 buffer_put_int(&m, fwd->listen_port);
1346 buffer_put_cstring(&m,
1347 fwd->connect_host == NULL ? "" : fwd->connect_host);
1348 buffer_put_int(&m, fwd->connect_port);
1349
1350 if (mux_client_write_packet(fd, &m) != 0)
1351 fatal("%s: write packet: %s", __func__, strerror(errno));
1352
1353 buffer_clear(&m);
1354
1355 /* Read their reply */
1356 if (mux_client_read_packet(fd, &m) != 0) {
1357 buffer_free(&m);
1358 return -1;
1359 }
1360
1361 type = buffer_get_int(&m);
1362 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1363 fatal("%s: out of sequence reply: my id %u theirs %u",
1364 __func__, muxclient_request_id, rid);
1365 switch (type) {
1366 case MUX_S_OK:
1367 break;
1368 case MUX_S_PERMISSION_DENIED:
1369 e = buffer_get_string(&m, NULL);
1370 buffer_free(&m);
1371 error("Master refused forwarding request: %s", e);
1372 return -1;
1373 case MUX_S_FAILURE:
1374 e = buffer_get_string(&m, NULL);
1375 buffer_free(&m);
1376 error("%s: session request failed: %s", __func__, e);
1377 return -1;
1378 default:
1379 fatal("%s: unexpected response from master 0x%08x",
1380 __func__, type);
1381 }
1382 buffer_free(&m);
1383
1384 muxclient_request_id++;
1385 return 0;
1386 }
1387
1388 static int
1389 mux_client_request_forwards(int fd)
1390 {
1391 int i;
1392
1393 debug3("%s: requesting forwardings: %d local, %d remote", __func__,
1394 options.num_local_forwards, options.num_remote_forwards);
1395
1396 /* XXX ExitOnForwardingFailure */
1397 for (i = 0; i < options.num_local_forwards; i++) {
1398 if (mux_client_request_forward(fd,
1399 options.local_forwards[i].connect_port == 0 ?
1400 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1401 options.local_forwards + i) != 0)
1402 return -1;
1403 }
1404 for (i = 0; i < options.num_remote_forwards; i++) {
1405 if (mux_client_request_forward(fd, MUX_FWD_REMOTE,
1406 options.remote_forwards + i) != 0)
1407 return -1;
1408 }
1409 return 0;
1410 }
1411
1412 static int
1413 mux_client_request_session(int fd)
1414 {
1415 Buffer m;
1416 char *e, *term;
1417 u_int i, rid, sid, esid, exitval, type, exitval_seen;
1418 extern char **environ;
1419 int devnull;
1420
1421 debug3("%s: entering", __func__);
1422
1423 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1424 error("%s: master alive request failed", __func__);
1425 return -1;
1426 }
1427
1428 signal(SIGPIPE, SIG_IGN);
1429
1430 if (stdin_null_flag) {
1431 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1432 fatal("open(/dev/null): %s", strerror(errno));
1433 if (dup2(devnull, STDIN_FILENO) == -1)
1434 fatal("dup2: %s", strerror(errno));
1435 if (devnull > STDERR_FILENO)
1436 close(devnull);
1437 }
1438
1439 term = getenv("TERM");
1440
1441 buffer_init(&m);
1442 buffer_put_int(&m, MUX_C_NEW_SESSION);
1443 buffer_put_int(&m, muxclient_request_id);
1444 buffer_put_cstring(&m, ""); /* reserved */
1445 buffer_put_int(&m, tty_flag);
1446 buffer_put_int(&m, options.forward_x11);
1447 buffer_put_int(&m, options.forward_agent);
1448 buffer_put_int(&m, subsystem_flag);
1449 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ?
1450 0xffffffff : (u_int)options.escape_char);
1451 buffer_put_cstring(&m, term == NULL ? "" : term);
1452 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command));
1453
1454 if (options.num_send_env > 0 && environ != NULL) {
1455 /* Pass environment */
1456 for (i = 0; environ[i] != NULL; i++) {
1457 if (env_permitted(environ[i])) {
1458 buffer_put_cstring(&m, environ[i]);
1459 }
1460 }
1461 }
1462
1463 if (mux_client_write_packet(fd, &m) != 0)
1464 fatal("%s: write packet: %s", __func__, strerror(errno));
1465
1466 /* Send the stdio file descriptors */
1467 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1468 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1469 mm_send_fd(fd, STDERR_FILENO) == -1)
1470 fatal("%s: send fds failed", __func__);
1471
1472 debug3("%s: session request sent", __func__);
1473
1474 /* Read their reply */
1475 buffer_clear(&m);
1476 if (mux_client_read_packet(fd, &m) != 0) {
1477 error("%s: read from master failed: %s",
1478 __func__, strerror(errno));
1479 buffer_free(&m);
1480 return -1;
1481 }
1482
1483 type = buffer_get_int(&m);
1484 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1485 fatal("%s: out of sequence reply: my id %u theirs %u",
1486 __func__, muxclient_request_id, rid);
1487 switch (type) {
1488 case MUX_S_SESSION_OPENED:
1489 sid = buffer_get_int(&m);
1490 debug("%s: master session id: %u", __func__, sid);
1491 break;
1492 case MUX_S_PERMISSION_DENIED:
1493 e = buffer_get_string(&m, NULL);
1494 buffer_free(&m);
1495 error("Master refused forwarding request: %s", e);
1496 return -1;
1497 case MUX_S_FAILURE:
1498 e = buffer_get_string(&m, NULL);
1499 buffer_free(&m);
1500 error("%s: forwarding request failed: %s", __func__, e);
1501 return -1;
1502 default:
1503 buffer_free(&m);
1504 error("%s: unexpected response from master 0x%08x",
1505 __func__, type);
1506 return -1;
1507 }
1508 muxclient_request_id++;
1509
1510 signal(SIGHUP, control_client_sighandler);
1511 signal(SIGINT, control_client_sighandler);
1512 signal(SIGTERM, control_client_sighandler);
1513 signal(SIGWINCH, control_client_sigrelay);
1514
1515 if (tty_flag)
1516 enter_raw_mode(force_tty_flag);
1517
1518 /*
1519 * Stick around until the controlee closes the client_fd.
1520 * Before it does, it is expected to write an exit message.
1521 * This process must read the value and wait for the closure of
1522 * the client_fd; if this one closes early, the multiplex master will
1523 * terminate early too (possibly losing data).
1524 */
1525 for (exitval = 255, exitval_seen = 0;;) {
1526 buffer_clear(&m);
1527 if (mux_client_read_packet(fd, &m) != 0)
1528 break;
1529 type = buffer_get_int(&m);
1530 if (type != MUX_S_EXIT_MESSAGE) {
1531 e = buffer_get_string(&m, NULL);
1532 fatal("%s: master returned error: %s", __func__, e);
1533 }
1534 if ((esid = buffer_get_int(&m)) != sid)
1535 fatal("%s: exit on unknown session: my id %u theirs %u",
1536 __func__, sid, esid);
1537 debug("%s: master session id: %u", __func__, sid);
1538 if (exitval_seen)
1539 fatal("%s: exitval sent twice", __func__);
1540 exitval = buffer_get_int(&m);
1541 exitval_seen = 1;
1542 }
1543
1544 close(fd);
1545 leave_raw_mode(force_tty_flag);
1546
1547 if (muxclient_terminate) {
1548 debug2("Exiting on signal %d", muxclient_terminate);
1549 exitval = 255;
1550 } else if (!exitval_seen) {
1551 debug2("Control master terminated unexpectedly");
1552 exitval = 255;
1553 } else
1554 debug2("Received exit status from master %d", exitval);
1555
1556 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1557 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
1558
1559 exit(exitval);
1560 }
1561
1562 static int
1563 mux_client_request_stdio_fwd(int fd)
1564 {
1565 Buffer m;
1566 char *e;
1567 u_int type, rid, sid;
1568 int devnull;
1569
1570 debug3("%s: entering", __func__);
1571
1572 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1573 error("%s: master alive request failed", __func__);
1574 return -1;
1575 }
1576
1577 signal(SIGPIPE, SIG_IGN);
1578
1579 if (stdin_null_flag) {
1580 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1581 fatal("open(/dev/null): %s", strerror(errno));
1582 if (dup2(devnull, STDIN_FILENO) == -1)
1583 fatal("dup2: %s", strerror(errno));
1584 if (devnull > STDERR_FILENO)
1585 close(devnull);
1586 }
1587
1588 buffer_init(&m);
1589 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD);
1590 buffer_put_int(&m, muxclient_request_id);
1591 buffer_put_cstring(&m, ""); /* reserved */
1592 buffer_put_cstring(&m, stdio_forward_host);
1593 buffer_put_int(&m, stdio_forward_port);
1594
1595 if (mux_client_write_packet(fd, &m) != 0)
1596 fatal("%s: write packet: %s", __func__, strerror(errno));
1597
1598 /* Send the stdio file descriptors */
1599 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1600 mm_send_fd(fd, STDOUT_FILENO) == -1)
1601 fatal("%s: send fds failed", __func__);
1602
1603 debug3("%s: stdio forward request sent", __func__);
1604
1605 /* Read their reply */
1606 buffer_clear(&m);
1607
1608 if (mux_client_read_packet(fd, &m) != 0) {
1609 error("%s: read from master failed: %s",
1610 __func__, strerror(errno));
1611 buffer_free(&m);
1612 return -1;
1613 }
1614
1615 type = buffer_get_int(&m);
1616 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1617 fatal("%s: out of sequence reply: my id %u theirs %u",
1618 __func__, muxclient_request_id, rid);
1619 switch (type) {
1620 case MUX_S_SESSION_OPENED:
1621 sid = buffer_get_int(&m);
1622 debug("%s: master session id: %u", __func__, sid);
1623 break;
1624 case MUX_S_PERMISSION_DENIED:
1625 e = buffer_get_string(&m, NULL);
1626 buffer_free(&m);
1627 fatal("Master refused forwarding request: %s", e);
1628 case MUX_S_FAILURE:
1629 e = buffer_get_string(&m, NULL);
1630 buffer_free(&m);
1631 fatal("%s: stdio forwarding request failed: %s", __func__, e);
1632 default:
1633 buffer_free(&m);
1634 error("%s: unexpected response from master 0x%08x",
1635 __func__, type);
1636 return -1;
1637 }
1638 muxclient_request_id++;
1639
1640 signal(SIGHUP, control_client_sighandler);
1641 signal(SIGINT, control_client_sighandler);
1642 signal(SIGTERM, control_client_sighandler);
1643 signal(SIGWINCH, control_client_sigrelay);
1644
1645 /*
1646 * Stick around until the controlee closes the client_fd.
1647 */
1648 buffer_clear(&m);
1649 if (mux_client_read_packet(fd, &m) != 0) {
1650 if (errno == EPIPE ||
1651 (errno == EINTR && muxclient_terminate != 0))
1652 return 0;
1653 fatal("%s: mux_client_read_packet: %s",
1654 __func__, strerror(errno));
1655 }
1656 fatal("%s: master returned unexpected message %u", __func__, type);
1657 }
1658
1659 /* Multiplex client main loop. */
1660 void
1661 muxclient(const char *path)
1662 {
1663 struct sockaddr_un addr;
1664 socklen_t sun_len;
1665 int sock;
1666 u_int pid;
1667
1668 if (muxclient_command == 0) {
1669 if (stdio_forward_host != NULL)
1670 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
1671 else
1672 muxclient_command = SSHMUX_COMMAND_OPEN;
1673 }
1674
1675 switch (options.control_master) {
1676 case SSHCTL_MASTER_AUTO:
1677 case SSHCTL_MASTER_AUTO_ASK:
1678 debug("auto-mux: Trying existing master");
1679 /* FALLTHROUGH */
1680 case SSHCTL_MASTER_NO:
1681 break;
1682 default:
1683 return;
1684 }
1685
1686 memset(&addr, '\0', sizeof(addr));
1687 addr.sun_family = AF_UNIX;
1688 sun_len = offsetof(struct sockaddr_un, sun_path) +
1689 strlen(path) + 1;
1690
1691 if (strlcpy(addr.sun_path, path,
1692 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1693 fatal("ControlPath too long");
1694
1695 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1696 fatal("%s socket(): %s", __func__, strerror(errno));
1697
1698 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) {
1699 switch (muxclient_command) {
1700 case SSHMUX_COMMAND_OPEN:
1701 case SSHMUX_COMMAND_STDIO_FWD:
1702 break;
1703 default:
1704 fatal("Control socket connect(%.100s): %s", path,
1705 strerror(errno));
1706 }
1707 if (errno == ENOENT)
1708 debug("Control socket \"%.100s\" does not exist", path);
1709 else {
1710 error("Control socket connect(%.100s): %s", path,
1711 strerror(errno));
1712 }
1713 close(sock);
1714 return;
1715 }
1716 set_nonblock(sock);
1717
1718 if (mux_client_hello_exchange(sock) != 0) {
1719 error("%s: master hello exchange failed", __func__);
1720 close(sock);
1721 return;
1722 }
1723
1724 switch (muxclient_command) {
1725 case SSHMUX_COMMAND_ALIVE_CHECK:
1726 if ((pid = mux_client_request_alive(sock)) == 0)
1727 fatal("%s: master alive check failed", __func__);
1728 fprintf(stderr, "Master running (pid=%d)\r\n", pid);
1729 exit(0);
1730 case SSHMUX_COMMAND_TERMINATE:
1731 mux_client_request_terminate(sock);
1732 fprintf(stderr, "Exit request sent.\r\n");
1733 exit(0);
1734 case SSHMUX_COMMAND_OPEN:
1735 if (mux_client_request_forwards(sock) != 0) {
1736 error("%s: master forward request failed", __func__);
1737 return;
1738 }
1739 mux_client_request_session(sock);
1740 return;
1741 case SSHMUX_COMMAND_STDIO_FWD:
1742 mux_client_request_stdio_fwd(sock);
1743 exit(0);
1744 default:
1745 fatal("unrecognised muxclient_command %d", muxclient_command);
1746 }
1747 }
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