1 /* $OpenBSD: mux.c,v 1.54 2015/08/19 23:18:26 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/stat.h>
37 #include <sys/socket.h>
38 #include <sys/un.h>
39
40 #include <errno.h>
41 #include <fcntl.h>
42 #include <signal.h>
43 #include <stdarg.h>
44 #include <stddef.h>
45 #include <stdlib.h>
46 #include <stdio.h>
47 #include <string.h>
48 #include <unistd.h>
49 #ifdef HAVE_PATHS_H
50 #include <paths.h>
51 #endif
52
53 #ifdef HAVE_POLL_H
54 #include <poll.h>
55 #else
56 # ifdef HAVE_SYS_POLL_H
57 # include <sys/poll.h>
58 # endif
59 #endif
60
61 #ifdef HAVE_UTIL_H
62 # include <util.h>
63 #endif
64
65 #include "openbsd-compat/sys-queue.h"
66 #include "xmalloc.h"
67 #include "log.h"
68 #include "ssh.h"
69 #include "ssh2.h"
70 #include "pathnames.h"
71 #include "misc.h"
72 #include "match.h"
73 #include "buffer.h"
74 #include "channels.h"
75 #include "msg.h"
76 #include "packet.h"
77 #include "monitor_fdpass.h"
78 #include "sshpty.h"
79 #include "key.h"
80 #include "readconf.h"
81 #include "clientloop.h"
82
83 /* from ssh.c */
84 extern int tty_flag;
85 extern Options options;
86 extern int stdin_null_flag;
87 extern char *host;
88 extern int subsystem_flag;
89 extern Buffer command;
90 extern volatile sig_atomic_t quit_pending;
91 extern char *stdio_forward_host;
92 extern int stdio_forward_port;
93
94 /* Context for session open confirmation callback */
95 struct mux_session_confirm_ctx {
96 u_int want_tty;
97 u_int want_subsys;
98 u_int want_x_fwd;
99 u_int want_agent_fwd;
100 Buffer cmd;
101 char *term;
102 struct termios tio;
103 char **env;
104 u_int rid;
105 };
106
107 /* Context for stdio fwd open confirmation callback */
108 struct mux_stdio_confirm_ctx {
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 static void mux_stdio_confirm(int, int, void *);
165
166 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *);
167 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *);
168 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *);
169 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *);
170 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *);
171 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *);
172 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *);
173 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *);
174
175 static const struct {
176 u_int type;
177 int (*handler)(u_int, Channel *, Buffer *, Buffer *);
178 } mux_master_handlers[] = {
179 { MUX_MSG_HELLO, process_mux_master_hello },
180 { MUX_C_NEW_SESSION, process_mux_new_session },
181 { MUX_C_ALIVE_CHECK, process_mux_alive_check },
182 { MUX_C_TERMINATE, process_mux_terminate },
183 { MUX_C_OPEN_FWD, process_mux_open_fwd },
184 { MUX_C_CLOSE_FWD, process_mux_close_fwd },
185 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd },
186 { MUX_C_STOP_LISTENING, process_mux_stop_listening },
187 { 0, NULL }
188 };
189
190 /* Cleanup callback fired on closure of mux slave _session_ channel */
191 /* ARGSUSED */
192 static void
mux_master_session_cleanup_cb(int cid,void * unused)193 mux_master_session_cleanup_cb(int cid, void *unused)
194 {
195 Channel *cc, *c = channel_by_id(cid);
196
197 debug3("%s: entering for channel %d", __func__, cid);
198 if (c == NULL)
199 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
200 if (c->ctl_chan != -1) {
201 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
202 fatal("%s: channel %d missing control channel %d",
203 __func__, c->self, c->ctl_chan);
204 c->ctl_chan = -1;
205 cc->remote_id = -1;
206 chan_rcvd_oclose(cc);
207 }
208 channel_cancel_cleanup(c->self);
209 }
210
211 /* Cleanup callback fired on closure of mux slave _control_ channel */
212 /* ARGSUSED */
213 static void
mux_master_control_cleanup_cb(int cid,void * unused)214 mux_master_control_cleanup_cb(int cid, void *unused)
215 {
216 Channel *sc, *c = channel_by_id(cid);
217
218 debug3("%s: entering for channel %d", __func__, cid);
219 if (c == NULL)
220 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
221 if (c->remote_id != -1) {
222 if ((sc = channel_by_id(c->remote_id)) == NULL)
223 fatal("%s: channel %d missing session channel %d",
224 __func__, c->self, c->remote_id);
225 c->remote_id = -1;
226 sc->ctl_chan = -1;
227 if (sc->type != SSH_CHANNEL_OPEN &&
228 sc->type != SSH_CHANNEL_OPENING) {
229 debug2("%s: channel %d: not open", __func__, sc->self);
230 chan_mark_dead(sc);
231 } else {
232 if (sc->istate == CHAN_INPUT_OPEN)
233 chan_read_failed(sc);
234 if (sc->ostate == CHAN_OUTPUT_OPEN)
235 chan_write_failed(sc);
236 }
237 }
238 channel_cancel_cleanup(c->self);
239 }
240
241 /* Check mux client environment variables before passing them to mux master. */
242 static int
env_permitted(char * env)243 env_permitted(char *env)
244 {
245 int i, ret;
246 char name[1024], *cp;
247
248 if ((cp = strchr(env, '=')) == NULL || cp == env)
249 return 0;
250 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
251 if (ret <= 0 || (size_t)ret >= sizeof(name)) {
252 error("env_permitted: name '%.100s...' too long", env);
253 return 0;
254 }
255
256 for (i = 0; i < options.num_send_env; i++)
257 if (match_pattern(name, options.send_env[i]))
258 return 1;
259
260 return 0;
261 }
262
263 /* Mux master protocol message handlers */
264
265 static int
process_mux_master_hello(u_int rid,Channel * c,Buffer * m,Buffer * r)266 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r)
267 {
268 u_int ver;
269 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
270
271 if (state == NULL)
272 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self);
273 if (state->hello_rcvd) {
274 error("%s: HELLO received twice", __func__);
275 return -1;
276 }
277 if (buffer_get_int_ret(&ver, m) != 0) {
278 malf:
279 error("%s: malformed message", __func__);
280 return -1;
281 }
282 if (ver != SSHMUX_VER) {
283 error("Unsupported multiplexing protocol version %d "
284 "(expected %d)", ver, SSHMUX_VER);
285 return -1;
286 }
287 debug2("%s: channel %d slave version %u", __func__, c->self, ver);
288
289 /* No extensions are presently defined */
290 while (buffer_len(m) > 0) {
291 char *name = buffer_get_string_ret(m, NULL);
292 char *value = buffer_get_string_ret(m, NULL);
293
294 if (name == NULL || value == NULL) {
295 free(name);
296 free(value);
297 goto malf;
298 }
299 debug2("Unrecognised slave extension \"%s\"", name);
300 free(name);
301 free(value);
302 }
303 state->hello_rcvd = 1;
304 return 0;
305 }
306
307 static int
process_mux_new_session(u_int rid,Channel * c,Buffer * m,Buffer * r)308 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
309 {
310 Channel *nc;
311 struct mux_session_confirm_ctx *cctx;
312 char *reserved, *cmd, *cp;
313 u_int i, j, len, env_len, escape_char, window, packetmax;
314 int new_fd[3];
315
316 /* Reply for SSHMUX_COMMAND_OPEN */
317 cctx = xcalloc(1, sizeof(*cctx));
318 cctx->term = NULL;
319 cctx->rid = rid;
320 cmd = reserved = NULL;
321 cctx->env = NULL;
322 env_len = 0;
323 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
324 buffer_get_int_ret(&cctx->want_tty, m) != 0 ||
325 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 ||
326 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 ||
327 buffer_get_int_ret(&cctx->want_subsys, m) != 0 ||
328 buffer_get_int_ret(&escape_char, m) != 0 ||
329 (cctx->term = buffer_get_string_ret(m, &len)) == NULL ||
330 (cmd = buffer_get_string_ret(m, &len)) == NULL) {
331 malf:
332 free(cmd);
333 free(reserved);
334 for (j = 0; j < env_len; j++)
335 free(cctx->env[j]);
336 free(cctx->env);
337 free(cctx->term);
338 free(cctx);
339 error("%s: malformed message", __func__);
340 return -1;
341 }
342 free(reserved);
343 reserved = NULL;
344
345 while (buffer_len(m) > 0) {
346 #define MUX_MAX_ENV_VARS 4096
347 if ((cp = buffer_get_string_ret(m, &len)) == NULL)
348 goto malf;
349 if (!env_permitted(cp)) {
350 free(cp);
351 continue;
352 }
353 cctx->env = xreallocarray(cctx->env, env_len + 2,
354 sizeof(*cctx->env));
355 cctx->env[env_len++] = cp;
356 cctx->env[env_len] = NULL;
357 if (env_len > MUX_MAX_ENV_VARS) {
358 error(">%d environment variables received, ignoring "
359 "additional", MUX_MAX_ENV_VARS);
360 break;
361 }
362 }
363
364 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, "
365 "term \"%s\", cmd \"%s\", env %u", __func__, c->self,
366 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
367 cctx->want_subsys, cctx->term, cmd, env_len);
368
369 buffer_init(&cctx->cmd);
370 buffer_append(&cctx->cmd, cmd, strlen(cmd));
371 free(cmd);
372 cmd = NULL;
373
374 /* Gather fds from client */
375 for(i = 0; i < 3; i++) {
376 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
377 error("%s: failed to receive fd %d from slave",
378 __func__, i);
379 for (j = 0; j < i; j++)
380 close(new_fd[j]);
381 for (j = 0; j < env_len; j++)
382 free(cctx->env[j]);
383 free(cctx->env);
384 free(cctx->term);
385 buffer_free(&cctx->cmd);
386 free(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 free(cctx->term);
412 if (env_len != 0) {
413 for (i = 0; i < env_len; i++)
414 free(cctx->env[i]);
415 free(cctx->env);
416 }
417 buffer_free(&cctx->cmd);
418 free(cctx);
419 return 0;
420 }
421
422 if (options.control_master == SSHCTL_MASTER_ASK ||
423 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
424 if (!ask_permission("Allow shared connection to %s? ", host)) {
425 debug2("%s: session refused by user", __func__);
426 /* prepare reply */
427 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
428 buffer_put_int(r, rid);
429 buffer_put_cstring(r, "Permission denied");
430 goto cleanup;
431 }
432 }
433
434 /* Try to pick up ttymodes from client before it goes raw */
435 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
436 error("%s: tcgetattr: %s", __func__, strerror(errno));
437
438 /* enable nonblocking unless tty */
439 if (!isatty(new_fd[0]))
440 set_nonblock(new_fd[0]);
441 if (!isatty(new_fd[1]))
442 set_nonblock(new_fd[1]);
443 if (!isatty(new_fd[2]))
444 set_nonblock(new_fd[2]);
445
446 window = CHAN_SES_WINDOW_DEFAULT;
447 packetmax = CHAN_SES_PACKET_DEFAULT;
448 if (cctx->want_tty) {
449 window >>= 1;
450 packetmax >>= 1;
451 }
452
453 nc = channel_new("session", SSH_CHANNEL_OPENING,
454 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
455 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
456
457 nc->ctl_chan = c->self; /* link session -> control channel */
458 c->remote_id = nc->self; /* link control -> session channel */
459
460 if (cctx->want_tty && escape_char != 0xffffffff) {
461 channel_register_filter(nc->self,
462 client_simple_escape_filter, NULL,
463 client_filter_cleanup,
464 client_new_escape_filter_ctx((int)escape_char));
465 }
466
467 debug2("%s: channel_new: %d linked to control channel %d",
468 __func__, nc->self, nc->ctl_chan);
469
470 channel_send_open(nc->self);
471 channel_register_open_confirm(nc->self, mux_session_confirm, cctx);
472 c->mux_pause = 1; /* stop handling messages until open_confirm done */
473 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
474
475 /* reply is deferred, sent by mux_session_confirm */
476 return 0;
477 }
478
479 static int
process_mux_alive_check(u_int rid,Channel * c,Buffer * m,Buffer * r)480 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r)
481 {
482 debug2("%s: channel %d: alive check", __func__, c->self);
483
484 /* prepare reply */
485 buffer_put_int(r, MUX_S_ALIVE);
486 buffer_put_int(r, rid);
487 buffer_put_int(r, (u_int)getpid());
488
489 return 0;
490 }
491
492 static int
process_mux_terminate(u_int rid,Channel * c,Buffer * m,Buffer * r)493 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r)
494 {
495 debug2("%s: channel %d: terminate request", __func__, c->self);
496
497 if (options.control_master == SSHCTL_MASTER_ASK ||
498 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
499 if (!ask_permission("Terminate shared connection to %s? ",
500 host)) {
501 debug2("%s: termination refused by user", __func__);
502 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
503 buffer_put_int(r, rid);
504 buffer_put_cstring(r, "Permission denied");
505 return 0;
506 }
507 }
508
509 quit_pending = 1;
510 buffer_put_int(r, MUX_S_OK);
511 buffer_put_int(r, rid);
512 /* XXX exit happens too soon - message never makes it to client */
513 return 0;
514 }
515
516 static char *
format_forward(u_int ftype,struct Forward * fwd)517 format_forward(u_int ftype, struct Forward *fwd)
518 {
519 char *ret;
520
521 switch (ftype) {
522 case MUX_FWD_LOCAL:
523 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
524 (fwd->listen_path != NULL) ? fwd->listen_path :
525 (fwd->listen_host == NULL) ?
526 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
527 fwd->listen_host, fwd->listen_port,
528 (fwd->connect_path != NULL) ? fwd->connect_path :
529 fwd->connect_host, fwd->connect_port);
530 break;
531 case MUX_FWD_DYNAMIC:
532 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
533 (fwd->listen_host == NULL) ?
534 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
535 fwd->listen_host, fwd->listen_port);
536 break;
537 case MUX_FWD_REMOTE:
538 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
539 (fwd->listen_path != NULL) ? fwd->listen_path :
540 (fwd->listen_host == NULL) ?
541 "LOCALHOST" : fwd->listen_host,
542 fwd->listen_port,
543 (fwd->connect_path != NULL) ? fwd->connect_path :
544 fwd->connect_host, fwd->connect_port);
545 break;
546 default:
547 fatal("%s: unknown forward type %u", __func__, ftype);
548 }
549 return ret;
550 }
551
552 static int
compare_host(const char * a,const char * b)553 compare_host(const char *a, const char *b)
554 {
555 if (a == NULL && b == NULL)
556 return 1;
557 if (a == NULL || b == NULL)
558 return 0;
559 return strcmp(a, b) == 0;
560 }
561
562 static int
compare_forward(struct Forward * a,struct Forward * b)563 compare_forward(struct Forward *a, struct Forward *b)
564 {
565 if (!compare_host(a->listen_host, b->listen_host))
566 return 0;
567 if (!compare_host(a->listen_path, b->listen_path))
568 return 0;
569 if (a->listen_port != b->listen_port)
570 return 0;
571 if (!compare_host(a->connect_host, b->connect_host))
572 return 0;
573 if (!compare_host(a->connect_path, b->connect_path))
574 return 0;
575 if (a->connect_port != b->connect_port)
576 return 0;
577
578 return 1;
579 }
580
581 static void
mux_confirm_remote_forward(int type,u_int32_t seq,void * ctxt)582 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
583 {
584 struct mux_channel_confirm_ctx *fctx = ctxt;
585 char *failmsg = NULL;
586 struct Forward *rfwd;
587 Channel *c;
588 Buffer out;
589
590 if ((c = channel_by_id(fctx->cid)) == NULL) {
591 /* no channel for reply */
592 error("%s: unknown channel", __func__);
593 return;
594 }
595 buffer_init(&out);
596 if (fctx->fid >= options.num_remote_forwards ||
597 (options.remote_forwards[fctx->fid].connect_path == NULL &&
598 options.remote_forwards[fctx->fid].connect_host == NULL)) {
599 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
600 goto fail;
601 }
602 rfwd = &options.remote_forwards[fctx->fid];
603 debug("%s: %s for: listen %d, connect %s:%d", __func__,
604 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
605 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
606 rfwd->connect_host, rfwd->connect_port);
607 if (type == SSH2_MSG_REQUEST_SUCCESS) {
608 if (rfwd->listen_port == 0) {
609 rfwd->allocated_port = packet_get_int();
610 debug("Allocated port %u for mux remote forward"
611 " to %s:%d", rfwd->allocated_port,
612 rfwd->connect_host, rfwd->connect_port);
613 buffer_put_int(&out, MUX_S_REMOTE_PORT);
614 buffer_put_int(&out, fctx->rid);
615 buffer_put_int(&out, rfwd->allocated_port);
616 channel_update_permitted_opens(rfwd->handle,
617 rfwd->allocated_port);
618 } else {
619 buffer_put_int(&out, MUX_S_OK);
620 buffer_put_int(&out, fctx->rid);
621 }
622 goto out;
623 } else {
624 if (rfwd->listen_port == 0)
625 channel_update_permitted_opens(rfwd->handle, -1);
626 if (rfwd->listen_path != NULL)
627 xasprintf(&failmsg, "remote port forwarding failed for "
628 "listen path %s", rfwd->listen_path);
629 else
630 xasprintf(&failmsg, "remote port forwarding failed for "
631 "listen port %d", rfwd->listen_port);
632
633 debug2("%s: clearing registered forwarding for listen %d, "
634 "connect %s:%d", __func__, rfwd->listen_port,
635 rfwd->connect_path ? rfwd->connect_path :
636 rfwd->connect_host, rfwd->connect_port);
637
638 free(rfwd->listen_host);
639 free(rfwd->listen_path);
640 free(rfwd->connect_host);
641 free(rfwd->connect_path);
642 memset(rfwd, 0, sizeof(*rfwd));
643 }
644 fail:
645 error("%s: %s", __func__, failmsg);
646 buffer_put_int(&out, MUX_S_FAILURE);
647 buffer_put_int(&out, fctx->rid);
648 buffer_put_cstring(&out, failmsg);
649 free(failmsg);
650 out:
651 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out));
652 buffer_free(&out);
653 if (c->mux_pause <= 0)
654 fatal("%s: mux_pause %d", __func__, c->mux_pause);
655 c->mux_pause = 0; /* start processing messages again */
656 }
657
658 static int
process_mux_open_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)659 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
660 {
661 struct Forward fwd;
662 char *fwd_desc = NULL;
663 char *listen_addr, *connect_addr;
664 u_int ftype;
665 u_int lport, cport;
666 int i, ret = 0, freefwd = 1;
667
668 memset(&fwd, 0, sizeof(fwd));
669
670 /* XXX - lport/cport check redundant */
671 if (buffer_get_int_ret(&ftype, m) != 0 ||
672 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL ||
673 buffer_get_int_ret(&lport, m) != 0 ||
674 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL ||
675 buffer_get_int_ret(&cport, m) != 0 ||
676 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
677 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
678 error("%s: malformed message", __func__);
679 ret = -1;
680 goto out;
681 }
682 if (*listen_addr == '\0') {
683 free(listen_addr);
684 listen_addr = NULL;
685 }
686 if (*connect_addr == '\0') {
687 free(connect_addr);
688 connect_addr = NULL;
689 }
690
691 memset(&fwd, 0, sizeof(fwd));
692 fwd.listen_port = lport;
693 if (fwd.listen_port == PORT_STREAMLOCAL)
694 fwd.listen_path = listen_addr;
695 else
696 fwd.listen_host = listen_addr;
697 fwd.connect_port = cport;
698 if (fwd.connect_port == PORT_STREAMLOCAL)
699 fwd.connect_path = connect_addr;
700 else
701 fwd.connect_host = connect_addr;
702
703 debug2("%s: channel %d: request %s", __func__, c->self,
704 (fwd_desc = format_forward(ftype, &fwd)));
705
706 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
707 ftype != MUX_FWD_DYNAMIC) {
708 logit("%s: invalid forwarding type %u", __func__, ftype);
709 invalid:
710 free(listen_addr);
711 free(connect_addr);
712 buffer_put_int(r, MUX_S_FAILURE);
713 buffer_put_int(r, rid);
714 buffer_put_cstring(r, "Invalid forwarding request");
715 return 0;
716 }
717 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) {
718 logit("%s: streamlocal and dynamic forwards "
719 "are mutually exclusive", __func__);
720 goto invalid;
721 }
722 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) {
723 logit("%s: invalid listen port %u", __func__,
724 fwd.listen_port);
725 goto invalid;
726 }
727 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536)
728 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) {
729 logit("%s: invalid connect port %u", __func__,
730 fwd.connect_port);
731 goto invalid;
732 }
733 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) {
734 logit("%s: missing connect host", __func__);
735 goto invalid;
736 }
737
738 /* Skip forwards that have already been requested */
739 switch (ftype) {
740 case MUX_FWD_LOCAL:
741 case MUX_FWD_DYNAMIC:
742 for (i = 0; i < options.num_local_forwards; i++) {
743 if (compare_forward(&fwd,
744 options.local_forwards + i)) {
745 exists:
746 debug2("%s: found existing forwarding",
747 __func__);
748 buffer_put_int(r, MUX_S_OK);
749 buffer_put_int(r, rid);
750 goto out;
751 }
752 }
753 break;
754 case MUX_FWD_REMOTE:
755 for (i = 0; i < options.num_remote_forwards; i++) {
756 if (compare_forward(&fwd,
757 options.remote_forwards + i)) {
758 if (fwd.listen_port != 0)
759 goto exists;
760 debug2("%s: found allocated port",
761 __func__);
762 buffer_put_int(r, MUX_S_REMOTE_PORT);
763 buffer_put_int(r, rid);
764 buffer_put_int(r,
765 options.remote_forwards[i].allocated_port);
766 goto out;
767 }
768 }
769 break;
770 }
771
772 if (options.control_master == SSHCTL_MASTER_ASK ||
773 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
774 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
775 debug2("%s: forwarding refused by user", __func__);
776 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
777 buffer_put_int(r, rid);
778 buffer_put_cstring(r, "Permission denied");
779 goto out;
780 }
781 }
782
783 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
784 if (!channel_setup_local_fwd_listener(&fwd,
785 &options.fwd_opts)) {
786 fail:
787 logit("slave-requested %s failed", fwd_desc);
788 buffer_put_int(r, MUX_S_FAILURE);
789 buffer_put_int(r, rid);
790 buffer_put_cstring(r, "Port forwarding failed");
791 goto out;
792 }
793 add_local_forward(&options, &fwd);
794 freefwd = 0;
795 } else {
796 struct mux_channel_confirm_ctx *fctx;
797
798 fwd.handle = channel_request_remote_forwarding(&fwd);
799 if (fwd.handle < 0)
800 goto fail;
801 add_remote_forward(&options, &fwd);
802 fctx = xcalloc(1, sizeof(*fctx));
803 fctx->cid = c->self;
804 fctx->rid = rid;
805 fctx->fid = options.num_remote_forwards - 1;
806 client_register_global_confirm(mux_confirm_remote_forward,
807 fctx);
808 freefwd = 0;
809 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
810 /* delayed reply in mux_confirm_remote_forward */
811 goto out;
812 }
813 buffer_put_int(r, MUX_S_OK);
814 buffer_put_int(r, rid);
815 out:
816 free(fwd_desc);
817 if (freefwd) {
818 free(fwd.listen_host);
819 free(fwd.listen_path);
820 free(fwd.connect_host);
821 free(fwd.connect_path);
822 }
823 return ret;
824 }
825
826 static int
process_mux_close_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)827 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
828 {
829 struct Forward fwd, *found_fwd;
830 char *fwd_desc = NULL;
831 const char *error_reason = NULL;
832 char *listen_addr = NULL, *connect_addr = NULL;
833 u_int ftype;
834 int i, ret = 0;
835 u_int lport, cport;
836
837 memset(&fwd, 0, sizeof(fwd));
838
839 if (buffer_get_int_ret(&ftype, m) != 0 ||
840 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL ||
841 buffer_get_int_ret(&lport, m) != 0 ||
842 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL ||
843 buffer_get_int_ret(&cport, m) != 0 ||
844 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
845 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
846 error("%s: malformed message", __func__);
847 ret = -1;
848 goto out;
849 }
850
851 if (*listen_addr == '\0') {
852 free(listen_addr);
853 listen_addr = NULL;
854 }
855 if (*connect_addr == '\0') {
856 free(connect_addr);
857 connect_addr = NULL;
858 }
859
860 memset(&fwd, 0, sizeof(fwd));
861 fwd.listen_port = lport;
862 if (fwd.listen_port == PORT_STREAMLOCAL)
863 fwd.listen_path = listen_addr;
864 else
865 fwd.listen_host = listen_addr;
866 fwd.connect_port = cport;
867 if (fwd.connect_port == PORT_STREAMLOCAL)
868 fwd.connect_path = connect_addr;
869 else
870 fwd.connect_host = connect_addr;
871
872 debug2("%s: channel %d: request cancel %s", __func__, c->self,
873 (fwd_desc = format_forward(ftype, &fwd)));
874
875 /* make sure this has been requested */
876 found_fwd = NULL;
877 switch (ftype) {
878 case MUX_FWD_LOCAL:
879 case MUX_FWD_DYNAMIC:
880 for (i = 0; i < options.num_local_forwards; i++) {
881 if (compare_forward(&fwd,
882 options.local_forwards + i)) {
883 found_fwd = options.local_forwards + i;
884 break;
885 }
886 }
887 break;
888 case MUX_FWD_REMOTE:
889 for (i = 0; i < options.num_remote_forwards; i++) {
890 if (compare_forward(&fwd,
891 options.remote_forwards + i)) {
892 found_fwd = options.remote_forwards + i;
893 break;
894 }
895 }
896 break;
897 }
898
899 if (found_fwd == NULL)
900 error_reason = "port not forwarded";
901 else if (ftype == MUX_FWD_REMOTE) {
902 /*
903 * This shouldn't fail unless we confused the host/port
904 * between options.remote_forwards and permitted_opens.
905 * However, for dynamic allocated listen ports we need
906 * to use the actual listen port.
907 */
908 if (channel_request_rforward_cancel(found_fwd) == -1)
909 error_reason = "port not in permitted opens";
910 } else { /* local and dynamic forwards */
911 /* Ditto */
912 if (channel_cancel_lport_listener(&fwd, fwd.connect_port,
913 &options.fwd_opts) == -1)
914 error_reason = "port not found";
915 }
916
917 if (error_reason == NULL) {
918 buffer_put_int(r, MUX_S_OK);
919 buffer_put_int(r, rid);
920
921 free(found_fwd->listen_host);
922 free(found_fwd->listen_path);
923 free(found_fwd->connect_host);
924 free(found_fwd->connect_path);
925 found_fwd->listen_host = found_fwd->connect_host = NULL;
926 found_fwd->listen_path = found_fwd->connect_path = NULL;
927 found_fwd->listen_port = found_fwd->connect_port = 0;
928 } else {
929 buffer_put_int(r, MUX_S_FAILURE);
930 buffer_put_int(r, rid);
931 buffer_put_cstring(r, error_reason);
932 }
933 out:
934 free(fwd_desc);
935 free(listen_addr);
936 free(connect_addr);
937
938 return ret;
939 }
940
941 static int
process_mux_stdio_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)942 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
943 {
944 Channel *nc;
945 char *reserved, *chost;
946 u_int cport, i, j;
947 int new_fd[2];
948 struct mux_stdio_confirm_ctx *cctx;
949
950 chost = reserved = NULL;
951 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
952 (chost = buffer_get_string_ret(m, NULL)) == NULL ||
953 buffer_get_int_ret(&cport, m) != 0) {
954 free(reserved);
955 free(chost);
956 error("%s: malformed message", __func__);
957 return -1;
958 }
959 free(reserved);
960
961 debug2("%s: channel %d: request stdio fwd to %s:%u",
962 __func__, c->self, chost, cport);
963
964 /* Gather fds from client */
965 for(i = 0; i < 2; i++) {
966 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
967 error("%s: failed to receive fd %d from slave",
968 __func__, i);
969 for (j = 0; j < i; j++)
970 close(new_fd[j]);
971 free(chost);
972
973 /* prepare reply */
974 buffer_put_int(r, MUX_S_FAILURE);
975 buffer_put_int(r, rid);
976 buffer_put_cstring(r,
977 "did not receive file descriptors");
978 return -1;
979 }
980 }
981
982 debug3("%s: got fds stdin %d, stdout %d", __func__,
983 new_fd[0], new_fd[1]);
984
985 /* XXX support multiple child sessions in future */
986 if (c->remote_id != -1) {
987 debug2("%s: session already open", __func__);
988 /* prepare reply */
989 buffer_put_int(r, MUX_S_FAILURE);
990 buffer_put_int(r, rid);
991 buffer_put_cstring(r, "Multiple sessions not supported");
992 cleanup:
993 close(new_fd[0]);
994 close(new_fd[1]);
995 free(chost);
996 return 0;
997 }
998
999 if (options.control_master == SSHCTL_MASTER_ASK ||
1000 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1001 if (!ask_permission("Allow forward to %s:%u? ",
1002 chost, cport)) {
1003 debug2("%s: stdio fwd refused by user", __func__);
1004 /* prepare reply */
1005 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
1006 buffer_put_int(r, rid);
1007 buffer_put_cstring(r, "Permission denied");
1008 goto cleanup;
1009 }
1010 }
1011
1012 /* enable nonblocking unless tty */
1013 if (!isatty(new_fd[0]))
1014 set_nonblock(new_fd[0]);
1015 if (!isatty(new_fd[1]))
1016 set_nonblock(new_fd[1]);
1017
1018 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]);
1019
1020 nc->ctl_chan = c->self; /* link session -> control channel */
1021 c->remote_id = nc->self; /* link control -> session channel */
1022
1023 debug2("%s: channel_new: %d linked to control channel %d",
1024 __func__, nc->self, nc->ctl_chan);
1025
1026 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
1027
1028 cctx = xcalloc(1, sizeof(*cctx));
1029 cctx->rid = rid;
1030 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx);
1031 c->mux_pause = 1; /* stop handling messages until open_confirm done */
1032
1033 /* reply is deferred, sent by mux_session_confirm */
1034 return 0;
1035 }
1036
1037 /* Callback on open confirmation in mux master for a mux stdio fwd session. */
1038 static void
mux_stdio_confirm(int id,int success,void * arg)1039 mux_stdio_confirm(int id, int success, void *arg)
1040 {
1041 struct mux_stdio_confirm_ctx *cctx = arg;
1042 Channel *c, *cc;
1043 Buffer reply;
1044
1045 if (cctx == NULL)
1046 fatal("%s: cctx == NULL", __func__);
1047 if ((c = channel_by_id(id)) == NULL)
1048 fatal("%s: no channel for id %d", __func__, id);
1049 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
1050 fatal("%s: channel %d lacks control channel %d", __func__,
1051 id, c->ctl_chan);
1052
1053 if (!success) {
1054 debug3("%s: sending failure reply", __func__);
1055 /* prepare reply */
1056 buffer_init(&reply);
1057 buffer_put_int(&reply, MUX_S_FAILURE);
1058 buffer_put_int(&reply, cctx->rid);
1059 buffer_put_cstring(&reply, "Session open refused by peer");
1060 goto done;
1061 }
1062
1063 debug3("%s: sending success reply", __func__);
1064 /* prepare reply */
1065 buffer_init(&reply);
1066 buffer_put_int(&reply, MUX_S_SESSION_OPENED);
1067 buffer_put_int(&reply, cctx->rid);
1068 buffer_put_int(&reply, c->self);
1069
1070 done:
1071 /* Send reply */
1072 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
1073 buffer_free(&reply);
1074
1075 if (cc->mux_pause <= 0)
1076 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1077 cc->mux_pause = 0; /* start processing messages again */
1078 c->open_confirm_ctx = NULL;
1079 free(cctx);
1080 }
1081
1082 static int
process_mux_stop_listening(u_int rid,Channel * c,Buffer * m,Buffer * r)1083 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
1084 {
1085 debug("%s: channel %d: stop listening", __func__, c->self);
1086
1087 if (options.control_master == SSHCTL_MASTER_ASK ||
1088 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1089 if (!ask_permission("Disable further multiplexing on shared "
1090 "connection to %s? ", host)) {
1091 debug2("%s: stop listen refused by user", __func__);
1092 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
1093 buffer_put_int(r, rid);
1094 buffer_put_cstring(r, "Permission denied");
1095 return 0;
1096 }
1097 }
1098
1099 if (mux_listener_channel != NULL) {
1100 channel_free(mux_listener_channel);
1101 client_stop_mux();
1102 free(options.control_path);
1103 options.control_path = NULL;
1104 mux_listener_channel = NULL;
1105 muxserver_sock = -1;
1106 }
1107
1108 /* prepare reply */
1109 buffer_put_int(r, MUX_S_OK);
1110 buffer_put_int(r, rid);
1111
1112 return 0;
1113 }
1114
1115 /* Channel callbacks fired on read/write from mux slave fd */
1116 static int
mux_master_read_cb(Channel * c)1117 mux_master_read_cb(Channel *c)
1118 {
1119 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
1120 Buffer in, out;
1121 const u_char *ptr;
1122 u_int type, rid, have, i;
1123 int ret = -1;
1124
1125 /* Setup ctx and */
1126 if (c->mux_ctx == NULL) {
1127 state = xcalloc(1, sizeof(*state));
1128 c->mux_ctx = state;
1129 channel_register_cleanup(c->self,
1130 mux_master_control_cleanup_cb, 0);
1131
1132 /* Send hello */
1133 buffer_init(&out);
1134 buffer_put_int(&out, MUX_MSG_HELLO);
1135 buffer_put_int(&out, SSHMUX_VER);
1136 /* no extensions */
1137 buffer_put_string(&c->output, buffer_ptr(&out),
1138 buffer_len(&out));
1139 buffer_free(&out);
1140 debug3("%s: channel %d: hello sent", __func__, c->self);
1141 return 0;
1142 }
1143
1144 buffer_init(&in);
1145 buffer_init(&out);
1146
1147 /* Channel code ensures that we receive whole packets */
1148 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) {
1149 malf:
1150 error("%s: malformed message", __func__);
1151 goto out;
1152 }
1153 buffer_append(&in, ptr, have);
1154
1155 if (buffer_get_int_ret(&type, &in) != 0)
1156 goto malf;
1157 debug3("%s: channel %d packet type 0x%08x len %u",
1158 __func__, c->self, type, buffer_len(&in));
1159
1160 if (type == MUX_MSG_HELLO)
1161 rid = 0;
1162 else {
1163 if (!state->hello_rcvd) {
1164 error("%s: expected MUX_MSG_HELLO(0x%08x), "
1165 "received 0x%08x", __func__, MUX_MSG_HELLO, type);
1166 goto out;
1167 }
1168 if (buffer_get_int_ret(&rid, &in) != 0)
1169 goto malf;
1170 }
1171
1172 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
1173 if (type == mux_master_handlers[i].type) {
1174 ret = mux_master_handlers[i].handler(rid, c, &in, &out);
1175 break;
1176 }
1177 }
1178 if (mux_master_handlers[i].handler == NULL) {
1179 error("%s: unsupported mux message 0x%08x", __func__, type);
1180 buffer_put_int(&out, MUX_S_FAILURE);
1181 buffer_put_int(&out, rid);
1182 buffer_put_cstring(&out, "unsupported request");
1183 ret = 0;
1184 }
1185 /* Enqueue reply packet */
1186 if (buffer_len(&out) != 0) {
1187 buffer_put_string(&c->output, buffer_ptr(&out),
1188 buffer_len(&out));
1189 }
1190 out:
1191 buffer_free(&in);
1192 buffer_free(&out);
1193 return ret;
1194 }
1195
1196 void
mux_exit_message(Channel * c,int exitval)1197 mux_exit_message(Channel *c, int exitval)
1198 {
1199 Buffer m;
1200 Channel *mux_chan;
1201
1202 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self,
1203 exitval);
1204
1205 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
1206 fatal("%s: channel %d missing mux channel %d",
1207 __func__, c->self, c->ctl_chan);
1208
1209 /* Append exit message packet to control socket output queue */
1210 buffer_init(&m);
1211 buffer_put_int(&m, MUX_S_EXIT_MESSAGE);
1212 buffer_put_int(&m, c->self);
1213 buffer_put_int(&m, exitval);
1214
1215 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
1216 buffer_free(&m);
1217 }
1218
1219 void
mux_tty_alloc_failed(Channel * c)1220 mux_tty_alloc_failed(Channel *c)
1221 {
1222 Buffer m;
1223 Channel *mux_chan;
1224
1225 debug3("%s: channel %d: TTY alloc failed", __func__, c->self);
1226
1227 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
1228 fatal("%s: channel %d missing mux channel %d",
1229 __func__, c->self, c->ctl_chan);
1230
1231 /* Append exit message packet to control socket output queue */
1232 buffer_init(&m);
1233 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL);
1234 buffer_put_int(&m, c->self);
1235
1236 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
1237 buffer_free(&m);
1238 }
1239
1240 /* Prepare a mux master to listen on a Unix domain socket. */
1241 void
muxserver_listen(void)1242 muxserver_listen(void)
1243 {
1244 mode_t old_umask;
1245 char *orig_control_path = options.control_path;
1246 char rbuf[16+1];
1247 u_int i, r;
1248 int oerrno;
1249
1250 if (options.control_path == NULL ||
1251 options.control_master == SSHCTL_MASTER_NO)
1252 return;
1253
1254 debug("setting up multiplex master socket");
1255
1256 /*
1257 * Use a temporary path before listen so we can pseudo-atomically
1258 * establish the listening socket in its final location to avoid
1259 * other processes racing in between bind() and listen() and hitting
1260 * an unready socket.
1261 */
1262 for (i = 0; i < sizeof(rbuf) - 1; i++) {
1263 r = arc4random_uniform(26+26+10);
1264 rbuf[i] = (r < 26) ? 'a' + r :
1265 (r < 26*2) ? 'A' + r - 26 :
1266 '0' + r - 26 - 26;
1267 }
1268 rbuf[sizeof(rbuf) - 1] = '\0';
1269 options.control_path = NULL;
1270 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
1271 debug3("%s: temporary control path %s", __func__, options.control_path);
1272
1273 old_umask = umask(0177);
1274 muxserver_sock = unix_listener(options.control_path, 64, 0);
1275 oerrno = errno;
1276 umask(old_umask);
1277 if (muxserver_sock < 0) {
1278 if (oerrno == EINVAL || oerrno == EADDRINUSE) {
1279 error("ControlSocket %s already exists, "
1280 "disabling multiplexing", options.control_path);
1281 disable_mux_master:
1282 if (muxserver_sock != -1) {
1283 close(muxserver_sock);
1284 muxserver_sock = -1;
1285 }
1286 free(orig_control_path);
1287 free(options.control_path);
1288 options.control_path = NULL;
1289 options.control_master = SSHCTL_MASTER_NO;
1290 return;
1291 } else {
1292 /* unix_listener() logs the error */
1293 cleanup_exit(255);
1294 }
1295 }
1296
1297 /* Now atomically "move" the mux socket into position */
1298 if (link(options.control_path, orig_control_path) != 0) {
1299 if (errno != EEXIST) {
1300 fatal("%s: link mux listener %s => %s: %s", __func__,
1301 options.control_path, orig_control_path,
1302 strerror(errno));
1303 }
1304 error("ControlSocket %s already exists, disabling multiplexing",
1305 orig_control_path);
1306 unlink(options.control_path);
1307 goto disable_mux_master;
1308 }
1309 unlink(options.control_path);
1310 free(options.control_path);
1311 options.control_path = orig_control_path;
1312
1313 set_nonblock(muxserver_sock);
1314
1315 mux_listener_channel = channel_new("mux listener",
1316 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
1317 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1318 0, options.control_path, 1);
1319 mux_listener_channel->mux_rcb = mux_master_read_cb;
1320 debug3("%s: mux listener channel %d fd %d", __func__,
1321 mux_listener_channel->self, mux_listener_channel->sock);
1322 }
1323
1324 /* Callback on open confirmation in mux master for a mux client session. */
1325 static void
mux_session_confirm(int id,int success,void * arg)1326 mux_session_confirm(int id, int success, void *arg)
1327 {
1328 struct mux_session_confirm_ctx *cctx = arg;
1329 const char *display;
1330 Channel *c, *cc;
1331 int i;
1332 Buffer reply;
1333
1334 if (cctx == NULL)
1335 fatal("%s: cctx == NULL", __func__);
1336 if ((c = channel_by_id(id)) == NULL)
1337 fatal("%s: no channel for id %d", __func__, id);
1338 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
1339 fatal("%s: channel %d lacks control channel %d", __func__,
1340 id, c->ctl_chan);
1341
1342 if (!success) {
1343 debug3("%s: sending failure reply", __func__);
1344 /* prepare reply */
1345 buffer_init(&reply);
1346 buffer_put_int(&reply, MUX_S_FAILURE);
1347 buffer_put_int(&reply, cctx->rid);
1348 buffer_put_cstring(&reply, "Session open refused by peer");
1349 goto done;
1350 }
1351
1352 display = getenv("DISPLAY");
1353 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1354 char *proto, *data;
1355
1356 /* Get reasonable local authentication information. */
1357 client_x11_get_proto(display, options.xauth_location,
1358 options.forward_x11_trusted, options.forward_x11_timeout,
1359 &proto, &data);
1360 /* Request forwarding with authentication spoofing. */
1361 debug("Requesting X11 forwarding with authentication "
1362 "spoofing.");
1363 x11_request_forwarding_with_spoofing(id, display, proto,
1364 data, 1);
1365 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1366 /* XXX exit_on_forward_failure */
1367 }
1368
1369 if (cctx->want_agent_fwd && options.forward_agent) {
1370 debug("Requesting authentication agent forwarding.");
1371 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1372 packet_send();
1373 }
1374
1375 client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
1376 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
1377
1378 debug3("%s: sending success reply", __func__);
1379 /* prepare reply */
1380 buffer_init(&reply);
1381 buffer_put_int(&reply, MUX_S_SESSION_OPENED);
1382 buffer_put_int(&reply, cctx->rid);
1383 buffer_put_int(&reply, c->self);
1384
1385 done:
1386 /* Send reply */
1387 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
1388 buffer_free(&reply);
1389
1390 if (cc->mux_pause <= 0)
1391 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1392 cc->mux_pause = 0; /* start processing messages again */
1393 c->open_confirm_ctx = NULL;
1394 buffer_free(&cctx->cmd);
1395 free(cctx->term);
1396 if (cctx->env != NULL) {
1397 for (i = 0; cctx->env[i] != NULL; i++)
1398 free(cctx->env[i]);
1399 free(cctx->env);
1400 }
1401 free(cctx);
1402 }
1403
1404 /* ** Multiplexing client support */
1405
1406 /* Exit signal handler */
1407 static void
control_client_sighandler(int signo)1408 control_client_sighandler(int signo)
1409 {
1410 muxclient_terminate = signo;
1411 }
1412
1413 /*
1414 * Relay signal handler - used to pass some signals from mux client to
1415 * mux master.
1416 */
1417 static void
control_client_sigrelay(int signo)1418 control_client_sigrelay(int signo)
1419 {
1420 int save_errno = errno;
1421
1422 if (muxserver_pid > 1)
1423 kill(muxserver_pid, signo);
1424
1425 errno = save_errno;
1426 }
1427
1428 static int
mux_client_read(int fd,Buffer * b,u_int need)1429 mux_client_read(int fd, Buffer *b, u_int need)
1430 {
1431 u_int have;
1432 ssize_t len;
1433 u_char *p;
1434 struct pollfd pfd;
1435
1436 pfd.fd = fd;
1437 pfd.events = POLLIN;
1438 p = buffer_append_space(b, need);
1439 for (have = 0; have < need; ) {
1440 if (muxclient_terminate) {
1441 errno = EINTR;
1442 return -1;
1443 }
1444 len = read(fd, p + have, need - have);
1445 if (len < 0) {
1446 switch (errno) {
1447 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1448 case EWOULDBLOCK:
1449 #endif
1450 case EAGAIN:
1451 (void)poll(&pfd, 1, -1);
1452 /* FALLTHROUGH */
1453 case EINTR:
1454 continue;
1455 default:
1456 return -1;
1457 }
1458 }
1459 if (len == 0) {
1460 errno = EPIPE;
1461 return -1;
1462 }
1463 have += (u_int)len;
1464 }
1465 return 0;
1466 }
1467
1468 static int
mux_client_write_packet(int fd,Buffer * m)1469 mux_client_write_packet(int fd, Buffer *m)
1470 {
1471 Buffer queue;
1472 u_int have, need;
1473 int oerrno, len;
1474 u_char *ptr;
1475 struct pollfd pfd;
1476
1477 pfd.fd = fd;
1478 pfd.events = POLLOUT;
1479 buffer_init(&queue);
1480 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m));
1481
1482 need = buffer_len(&queue);
1483 ptr = buffer_ptr(&queue);
1484
1485 for (have = 0; have < need; ) {
1486 if (muxclient_terminate) {
1487 buffer_free(&queue);
1488 errno = EINTR;
1489 return -1;
1490 }
1491 len = write(fd, ptr + have, need - have);
1492 if (len < 0) {
1493 switch (errno) {
1494 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1495 case EWOULDBLOCK:
1496 #endif
1497 case EAGAIN:
1498 (void)poll(&pfd, 1, -1);
1499 /* FALLTHROUGH */
1500 case EINTR:
1501 continue;
1502 default:
1503 oerrno = errno;
1504 buffer_free(&queue);
1505 errno = oerrno;
1506 return -1;
1507 }
1508 }
1509 if (len == 0) {
1510 buffer_free(&queue);
1511 errno = EPIPE;
1512 return -1;
1513 }
1514 have += (u_int)len;
1515 }
1516 buffer_free(&queue);
1517 return 0;
1518 }
1519
1520 static int
mux_client_read_packet(int fd,Buffer * m)1521 mux_client_read_packet(int fd, Buffer *m)
1522 {
1523 Buffer queue;
1524 u_int need, have;
1525 const u_char *ptr;
1526 int oerrno;
1527
1528 buffer_init(&queue);
1529 if (mux_client_read(fd, &queue, 4) != 0) {
1530 if ((oerrno = errno) == EPIPE)
1531 debug3("%s: read header failed: %s", __func__,
1532 strerror(errno));
1533 buffer_free(&queue);
1534 errno = oerrno;
1535 return -1;
1536 }
1537 need = get_u32(buffer_ptr(&queue));
1538 if (mux_client_read(fd, &queue, need) != 0) {
1539 oerrno = errno;
1540 debug3("%s: read body failed: %s", __func__, strerror(errno));
1541 buffer_free(&queue);
1542 errno = oerrno;
1543 return -1;
1544 }
1545 ptr = buffer_get_string_ptr(&queue, &have);
1546 buffer_append(m, ptr, have);
1547 buffer_free(&queue);
1548 return 0;
1549 }
1550
1551 static int
mux_client_hello_exchange(int fd)1552 mux_client_hello_exchange(int fd)
1553 {
1554 Buffer m;
1555 u_int type, ver;
1556
1557 buffer_init(&m);
1558 buffer_put_int(&m, MUX_MSG_HELLO);
1559 buffer_put_int(&m, SSHMUX_VER);
1560 /* no extensions */
1561
1562 if (mux_client_write_packet(fd, &m) != 0)
1563 fatal("%s: write packet: %s", __func__, strerror(errno));
1564
1565 buffer_clear(&m);
1566
1567 /* Read their HELLO */
1568 if (mux_client_read_packet(fd, &m) != 0) {
1569 buffer_free(&m);
1570 return -1;
1571 }
1572
1573 type = buffer_get_int(&m);
1574 if (type != MUX_MSG_HELLO)
1575 fatal("%s: expected HELLO (%u) received %u",
1576 __func__, MUX_MSG_HELLO, type);
1577 ver = buffer_get_int(&m);
1578 if (ver != SSHMUX_VER)
1579 fatal("Unsupported multiplexing protocol version %d "
1580 "(expected %d)", ver, SSHMUX_VER);
1581 debug2("%s: master version %u", __func__, ver);
1582 /* No extensions are presently defined */
1583 while (buffer_len(&m) > 0) {
1584 char *name = buffer_get_string(&m, NULL);
1585 char *value = buffer_get_string(&m, NULL);
1586
1587 debug2("Unrecognised master extension \"%s\"", name);
1588 free(name);
1589 free(value);
1590 }
1591 buffer_free(&m);
1592 return 0;
1593 }
1594
1595 static u_int
mux_client_request_alive(int fd)1596 mux_client_request_alive(int fd)
1597 {
1598 Buffer m;
1599 char *e;
1600 u_int pid, type, rid;
1601
1602 debug3("%s: entering", __func__);
1603
1604 buffer_init(&m);
1605 buffer_put_int(&m, MUX_C_ALIVE_CHECK);
1606 buffer_put_int(&m, muxclient_request_id);
1607
1608 if (mux_client_write_packet(fd, &m) != 0)
1609 fatal("%s: write packet: %s", __func__, strerror(errno));
1610
1611 buffer_clear(&m);
1612
1613 /* Read their reply */
1614 if (mux_client_read_packet(fd, &m) != 0) {
1615 buffer_free(&m);
1616 return 0;
1617 }
1618
1619 type = buffer_get_int(&m);
1620 if (type != MUX_S_ALIVE) {
1621 e = buffer_get_string(&m, NULL);
1622 fatal("%s: master returned error: %s", __func__, e);
1623 }
1624
1625 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1626 fatal("%s: out of sequence reply: my id %u theirs %u",
1627 __func__, muxclient_request_id, rid);
1628 pid = buffer_get_int(&m);
1629 buffer_free(&m);
1630
1631 debug3("%s: done pid = %u", __func__, pid);
1632
1633 muxclient_request_id++;
1634
1635 return pid;
1636 }
1637
1638 static void
mux_client_request_terminate(int fd)1639 mux_client_request_terminate(int fd)
1640 {
1641 Buffer m;
1642 char *e;
1643 u_int type, rid;
1644
1645 debug3("%s: entering", __func__);
1646
1647 buffer_init(&m);
1648 buffer_put_int(&m, MUX_C_TERMINATE);
1649 buffer_put_int(&m, muxclient_request_id);
1650
1651 if (mux_client_write_packet(fd, &m) != 0)
1652 fatal("%s: write packet: %s", __func__, strerror(errno));
1653
1654 buffer_clear(&m);
1655
1656 /* Read their reply */
1657 if (mux_client_read_packet(fd, &m) != 0) {
1658 /* Remote end exited already */
1659 if (errno == EPIPE) {
1660 buffer_free(&m);
1661 return;
1662 }
1663 fatal("%s: read from master failed: %s",
1664 __func__, strerror(errno));
1665 }
1666
1667 type = buffer_get_int(&m);
1668 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1669 fatal("%s: out of sequence reply: my id %u theirs %u",
1670 __func__, muxclient_request_id, rid);
1671 switch (type) {
1672 case MUX_S_OK:
1673 break;
1674 case MUX_S_PERMISSION_DENIED:
1675 e = buffer_get_string(&m, NULL);
1676 fatal("Master refused termination request: %s", e);
1677 case MUX_S_FAILURE:
1678 e = buffer_get_string(&m, NULL);
1679 fatal("%s: termination request failed: %s", __func__, e);
1680 default:
1681 fatal("%s: unexpected response from master 0x%08x",
1682 __func__, type);
1683 }
1684 buffer_free(&m);
1685 muxclient_request_id++;
1686 }
1687
1688 static int
mux_client_forward(int fd,int cancel_flag,u_int ftype,struct Forward * fwd)1689 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd)
1690 {
1691 Buffer m;
1692 char *e, *fwd_desc;
1693 u_int type, rid;
1694
1695 fwd_desc = format_forward(ftype, fwd);
1696 debug("Requesting %s %s",
1697 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc);
1698 free(fwd_desc);
1699
1700 buffer_init(&m);
1701 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD);
1702 buffer_put_int(&m, muxclient_request_id);
1703 buffer_put_int(&m, ftype);
1704 if (fwd->listen_path != NULL) {
1705 buffer_put_cstring(&m, fwd->listen_path);
1706 } else {
1707 buffer_put_cstring(&m,
1708 fwd->listen_host == NULL ? "" :
1709 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host));
1710 }
1711 buffer_put_int(&m, fwd->listen_port);
1712 if (fwd->connect_path != NULL) {
1713 buffer_put_cstring(&m, fwd->connect_path);
1714 } else {
1715 buffer_put_cstring(&m,
1716 fwd->connect_host == NULL ? "" : fwd->connect_host);
1717 }
1718 buffer_put_int(&m, fwd->connect_port);
1719
1720 if (mux_client_write_packet(fd, &m) != 0)
1721 fatal("%s: write packet: %s", __func__, strerror(errno));
1722
1723 buffer_clear(&m);
1724
1725 /* Read their reply */
1726 if (mux_client_read_packet(fd, &m) != 0) {
1727 buffer_free(&m);
1728 return -1;
1729 }
1730
1731 type = buffer_get_int(&m);
1732 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1733 fatal("%s: out of sequence reply: my id %u theirs %u",
1734 __func__, muxclient_request_id, rid);
1735 switch (type) {
1736 case MUX_S_OK:
1737 break;
1738 case MUX_S_REMOTE_PORT:
1739 if (cancel_flag)
1740 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__);
1741 fwd->allocated_port = buffer_get_int(&m);
1742 verbose("Allocated port %u for remote forward to %s:%d",
1743 fwd->allocated_port,
1744 fwd->connect_host ? fwd->connect_host : "",
1745 fwd->connect_port);
1746 if (muxclient_command == SSHMUX_COMMAND_FORWARD)
1747 fprintf(stdout, "%u\n", fwd->allocated_port);
1748 break;
1749 case MUX_S_PERMISSION_DENIED:
1750 e = buffer_get_string(&m, NULL);
1751 buffer_free(&m);
1752 error("Master refused forwarding request: %s", e);
1753 return -1;
1754 case MUX_S_FAILURE:
1755 e = buffer_get_string(&m, NULL);
1756 buffer_free(&m);
1757 error("%s: forwarding request failed: %s", __func__, e);
1758 return -1;
1759 default:
1760 fatal("%s: unexpected response from master 0x%08x",
1761 __func__, type);
1762 }
1763 buffer_free(&m);
1764
1765 muxclient_request_id++;
1766 return 0;
1767 }
1768
1769 static int
mux_client_forwards(int fd,int cancel_flag)1770 mux_client_forwards(int fd, int cancel_flag)
1771 {
1772 int i, ret = 0;
1773
1774 debug3("%s: %s forwardings: %d local, %d remote", __func__,
1775 cancel_flag ? "cancel" : "request",
1776 options.num_local_forwards, options.num_remote_forwards);
1777
1778 /* XXX ExitOnForwardingFailure */
1779 for (i = 0; i < options.num_local_forwards; i++) {
1780 if (mux_client_forward(fd, cancel_flag,
1781 options.local_forwards[i].connect_port == 0 ?
1782 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1783 options.local_forwards + i) != 0)
1784 ret = -1;
1785 }
1786 for (i = 0; i < options.num_remote_forwards; i++) {
1787 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE,
1788 options.remote_forwards + i) != 0)
1789 ret = -1;
1790 }
1791 return ret;
1792 }
1793
1794 static int
mux_client_request_session(int fd)1795 mux_client_request_session(int fd)
1796 {
1797 Buffer m;
1798 char *e, *term;
1799 u_int i, rid, sid, esid, exitval, type, exitval_seen;
1800 extern char **environ;
1801 int devnull, rawmode;
1802
1803 debug3("%s: entering", __func__);
1804
1805 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1806 error("%s: master alive request failed", __func__);
1807 return -1;
1808 }
1809
1810 signal(SIGPIPE, SIG_IGN);
1811
1812 if (stdin_null_flag) {
1813 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1814 fatal("open(/dev/null): %s", strerror(errno));
1815 if (dup2(devnull, STDIN_FILENO) == -1)
1816 fatal("dup2: %s", strerror(errno));
1817 if (devnull > STDERR_FILENO)
1818 close(devnull);
1819 }
1820
1821 term = getenv("TERM");
1822
1823 buffer_init(&m);
1824 buffer_put_int(&m, MUX_C_NEW_SESSION);
1825 buffer_put_int(&m, muxclient_request_id);
1826 buffer_put_cstring(&m, ""); /* reserved */
1827 buffer_put_int(&m, tty_flag);
1828 buffer_put_int(&m, options.forward_x11);
1829 buffer_put_int(&m, options.forward_agent);
1830 buffer_put_int(&m, subsystem_flag);
1831 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ?
1832 0xffffffff : (u_int)options.escape_char);
1833 buffer_put_cstring(&m, term == NULL ? "" : term);
1834 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command));
1835
1836 if (options.num_send_env > 0 && environ != NULL) {
1837 /* Pass environment */
1838 for (i = 0; environ[i] != NULL; i++) {
1839 if (env_permitted(environ[i])) {
1840 buffer_put_cstring(&m, environ[i]);
1841 }
1842 }
1843 }
1844
1845 if (mux_client_write_packet(fd, &m) != 0)
1846 fatal("%s: write packet: %s", __func__, strerror(errno));
1847
1848 /* Send the stdio file descriptors */
1849 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1850 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1851 mm_send_fd(fd, STDERR_FILENO) == -1)
1852 fatal("%s: send fds failed", __func__);
1853
1854 debug3("%s: session request sent", __func__);
1855
1856 /* Read their reply */
1857 buffer_clear(&m);
1858 if (mux_client_read_packet(fd, &m) != 0) {
1859 error("%s: read from master failed: %s",
1860 __func__, strerror(errno));
1861 buffer_free(&m);
1862 return -1;
1863 }
1864
1865 type = buffer_get_int(&m);
1866 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1867 fatal("%s: out of sequence reply: my id %u theirs %u",
1868 __func__, muxclient_request_id, rid);
1869 switch (type) {
1870 case MUX_S_SESSION_OPENED:
1871 sid = buffer_get_int(&m);
1872 debug("%s: master session id: %u", __func__, sid);
1873 break;
1874 case MUX_S_PERMISSION_DENIED:
1875 e = buffer_get_string(&m, NULL);
1876 buffer_free(&m);
1877 error("Master refused session request: %s", e);
1878 return -1;
1879 case MUX_S_FAILURE:
1880 e = buffer_get_string(&m, NULL);
1881 buffer_free(&m);
1882 error("%s: session request failed: %s", __func__, e);
1883 return -1;
1884 default:
1885 buffer_free(&m);
1886 error("%s: unexpected response from master 0x%08x",
1887 __func__, type);
1888 return -1;
1889 }
1890 muxclient_request_id++;
1891
1892 signal(SIGHUP, control_client_sighandler);
1893 signal(SIGINT, control_client_sighandler);
1894 signal(SIGTERM, control_client_sighandler);
1895 signal(SIGWINCH, control_client_sigrelay);
1896
1897 rawmode = tty_flag;
1898 if (tty_flag)
1899 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1900
1901 /*
1902 * Stick around until the controlee closes the client_fd.
1903 * Before it does, it is expected to write an exit message.
1904 * This process must read the value and wait for the closure of
1905 * the client_fd; if this one closes early, the multiplex master will
1906 * terminate early too (possibly losing data).
1907 */
1908 for (exitval = 255, exitval_seen = 0;;) {
1909 buffer_clear(&m);
1910 if (mux_client_read_packet(fd, &m) != 0)
1911 break;
1912 type = buffer_get_int(&m);
1913 switch (type) {
1914 case MUX_S_TTY_ALLOC_FAIL:
1915 if ((esid = buffer_get_int(&m)) != sid)
1916 fatal("%s: tty alloc fail on unknown session: "
1917 "my id %u theirs %u",
1918 __func__, sid, esid);
1919 leave_raw_mode(options.request_tty ==
1920 REQUEST_TTY_FORCE);
1921 rawmode = 0;
1922 continue;
1923 case MUX_S_EXIT_MESSAGE:
1924 if ((esid = buffer_get_int(&m)) != sid)
1925 fatal("%s: exit on unknown session: "
1926 "my id %u theirs %u",
1927 __func__, sid, esid);
1928 if (exitval_seen)
1929 fatal("%s: exitval sent twice", __func__);
1930 exitval = buffer_get_int(&m);
1931 exitval_seen = 1;
1932 continue;
1933 default:
1934 e = buffer_get_string(&m, NULL);
1935 fatal("%s: master returned error: %s", __func__, e);
1936 }
1937 }
1938
1939 close(fd);
1940 if (rawmode)
1941 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1942
1943 if (muxclient_terminate) {
1944 debug2("Exiting on signal %d", muxclient_terminate);
1945 exitval = 255;
1946 } else if (!exitval_seen) {
1947 debug2("Control master terminated unexpectedly");
1948 exitval = 255;
1949 } else
1950 debug2("Received exit status from master %d", exitval);
1951
1952 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1953 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
1954
1955 exit(exitval);
1956 }
1957
1958 static int
mux_client_request_stdio_fwd(int fd)1959 mux_client_request_stdio_fwd(int fd)
1960 {
1961 Buffer m;
1962 char *e;
1963 u_int type, rid, sid;
1964 int devnull;
1965
1966 debug3("%s: entering", __func__);
1967
1968 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1969 error("%s: master alive request failed", __func__);
1970 return -1;
1971 }
1972
1973 signal(SIGPIPE, SIG_IGN);
1974
1975 if (stdin_null_flag) {
1976 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1977 fatal("open(/dev/null): %s", strerror(errno));
1978 if (dup2(devnull, STDIN_FILENO) == -1)
1979 fatal("dup2: %s", strerror(errno));
1980 if (devnull > STDERR_FILENO)
1981 close(devnull);
1982 }
1983
1984 buffer_init(&m);
1985 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD);
1986 buffer_put_int(&m, muxclient_request_id);
1987 buffer_put_cstring(&m, ""); /* reserved */
1988 buffer_put_cstring(&m, stdio_forward_host);
1989 buffer_put_int(&m, stdio_forward_port);
1990
1991 if (mux_client_write_packet(fd, &m) != 0)
1992 fatal("%s: write packet: %s", __func__, strerror(errno));
1993
1994 /* Send the stdio file descriptors */
1995 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1996 mm_send_fd(fd, STDOUT_FILENO) == -1)
1997 fatal("%s: send fds failed", __func__);
1998
1999 debug3("%s: stdio forward request sent", __func__);
2000
2001 /* Read their reply */
2002 buffer_clear(&m);
2003
2004 if (mux_client_read_packet(fd, &m) != 0) {
2005 error("%s: read from master failed: %s",
2006 __func__, strerror(errno));
2007 buffer_free(&m);
2008 return -1;
2009 }
2010
2011 type = buffer_get_int(&m);
2012 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
2013 fatal("%s: out of sequence reply: my id %u theirs %u",
2014 __func__, muxclient_request_id, rid);
2015 switch (type) {
2016 case MUX_S_SESSION_OPENED:
2017 sid = buffer_get_int(&m);
2018 debug("%s: master session id: %u", __func__, sid);
2019 break;
2020 case MUX_S_PERMISSION_DENIED:
2021 e = buffer_get_string(&m, NULL);
2022 buffer_free(&m);
2023 fatal("Master refused stdio forwarding request: %s", e);
2024 case MUX_S_FAILURE:
2025 e = buffer_get_string(&m, NULL);
2026 buffer_free(&m);
2027 fatal("Stdio forwarding request failed: %s", e);
2028 default:
2029 buffer_free(&m);
2030 error("%s: unexpected response from master 0x%08x",
2031 __func__, type);
2032 return -1;
2033 }
2034 muxclient_request_id++;
2035
2036 signal(SIGHUP, control_client_sighandler);
2037 signal(SIGINT, control_client_sighandler);
2038 signal(SIGTERM, control_client_sighandler);
2039 signal(SIGWINCH, control_client_sigrelay);
2040
2041 /*
2042 * Stick around until the controlee closes the client_fd.
2043 */
2044 buffer_clear(&m);
2045 if (mux_client_read_packet(fd, &m) != 0) {
2046 if (errno == EPIPE ||
2047 (errno == EINTR && muxclient_terminate != 0))
2048 return 0;
2049 fatal("%s: mux_client_read_packet: %s",
2050 __func__, strerror(errno));
2051 }
2052 fatal("%s: master returned unexpected message %u", __func__, type);
2053 }
2054
2055 static void
mux_client_request_stop_listening(int fd)2056 mux_client_request_stop_listening(int fd)
2057 {
2058 Buffer m;
2059 char *e;
2060 u_int type, rid;
2061
2062 debug3("%s: entering", __func__);
2063
2064 buffer_init(&m);
2065 buffer_put_int(&m, MUX_C_STOP_LISTENING);
2066 buffer_put_int(&m, muxclient_request_id);
2067
2068 if (mux_client_write_packet(fd, &m) != 0)
2069 fatal("%s: write packet: %s", __func__, strerror(errno));
2070
2071 buffer_clear(&m);
2072
2073 /* Read their reply */
2074 if (mux_client_read_packet(fd, &m) != 0)
2075 fatal("%s: read from master failed: %s",
2076 __func__, strerror(errno));
2077
2078 type = buffer_get_int(&m);
2079 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
2080 fatal("%s: out of sequence reply: my id %u theirs %u",
2081 __func__, muxclient_request_id, rid);
2082 switch (type) {
2083 case MUX_S_OK:
2084 break;
2085 case MUX_S_PERMISSION_DENIED:
2086 e = buffer_get_string(&m, NULL);
2087 fatal("Master refused stop listening request: %s", e);
2088 case MUX_S_FAILURE:
2089 e = buffer_get_string(&m, NULL);
2090 fatal("%s: stop listening request failed: %s", __func__, e);
2091 default:
2092 fatal("%s: unexpected response from master 0x%08x",
2093 __func__, type);
2094 }
2095 buffer_free(&m);
2096 muxclient_request_id++;
2097 }
2098
2099 /* Multiplex client main loop. */
2100 void
muxclient(const char * path)2101 muxclient(const char *path)
2102 {
2103 struct sockaddr_un addr;
2104 socklen_t sun_len;
2105 int sock;
2106 u_int pid;
2107
2108 if (muxclient_command == 0) {
2109 if (stdio_forward_host != NULL)
2110 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
2111 else
2112 muxclient_command = SSHMUX_COMMAND_OPEN;
2113 }
2114
2115 switch (options.control_master) {
2116 case SSHCTL_MASTER_AUTO:
2117 case SSHCTL_MASTER_AUTO_ASK:
2118 debug("auto-mux: Trying existing master");
2119 /* FALLTHROUGH */
2120 case SSHCTL_MASTER_NO:
2121 break;
2122 default:
2123 return;
2124 }
2125
2126 memset(&addr, '\0', sizeof(addr));
2127 addr.sun_family = AF_UNIX;
2128 sun_len = offsetof(struct sockaddr_un, sun_path) +
2129 strlen(path) + 1;
2130
2131 if (strlcpy(addr.sun_path, path,
2132 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
2133 fatal("ControlPath too long");
2134
2135 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
2136 fatal("%s socket(): %s", __func__, strerror(errno));
2137
2138 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) {
2139 switch (muxclient_command) {
2140 case SSHMUX_COMMAND_OPEN:
2141 case SSHMUX_COMMAND_STDIO_FWD:
2142 break;
2143 default:
2144 fatal("Control socket connect(%.100s): %s", path,
2145 strerror(errno));
2146 }
2147 if (errno == ECONNREFUSED &&
2148 options.control_master != SSHCTL_MASTER_NO) {
2149 debug("Stale control socket %.100s, unlinking", path);
2150 unlink(path);
2151 } else if (errno == ENOENT) {
2152 debug("Control socket \"%.100s\" does not exist", path);
2153 } else {
2154 error("Control socket connect(%.100s): %s", path,
2155 strerror(errno));
2156 }
2157 close(sock);
2158 return;
2159 }
2160 set_nonblock(sock);
2161
2162 if (mux_client_hello_exchange(sock) != 0) {
2163 error("%s: master hello exchange failed", __func__);
2164 close(sock);
2165 return;
2166 }
2167
2168 switch (muxclient_command) {
2169 case SSHMUX_COMMAND_ALIVE_CHECK:
2170 if ((pid = mux_client_request_alive(sock)) == 0)
2171 fatal("%s: master alive check failed", __func__);
2172 fprintf(stderr, "Master running (pid=%d)\r\n", pid);
2173 exit(0);
2174 case SSHMUX_COMMAND_TERMINATE:
2175 mux_client_request_terminate(sock);
2176 fprintf(stderr, "Exit request sent.\r\n");
2177 exit(0);
2178 case SSHMUX_COMMAND_FORWARD:
2179 if (mux_client_forwards(sock, 0) != 0)
2180 fatal("%s: master forward request failed", __func__);
2181 exit(0);
2182 case SSHMUX_COMMAND_OPEN:
2183 if (mux_client_forwards(sock, 0) != 0) {
2184 error("%s: master forward request failed", __func__);
2185 return;
2186 }
2187 mux_client_request_session(sock);
2188 return;
2189 case SSHMUX_COMMAND_STDIO_FWD:
2190 mux_client_request_stdio_fwd(sock);
2191 exit(0);
2192 case SSHMUX_COMMAND_STOP:
2193 mux_client_request_stop_listening(sock);
2194 fprintf(stderr, "Stop listening request sent.\r\n");
2195 exit(0);
2196 case SSHMUX_COMMAND_CANCEL_FWD:
2197 if (mux_client_forwards(sock, 1) != 0)
2198 error("%s: master cancel forward request failed",
2199 __func__);
2200 exit(0);
2201 default:
2202 fatal("unrecognised muxclient_command %d", muxclient_command);
2203 }
2204 }
2205