1 /* $OpenBSD: mux.c,v 1.64 2017/01/21 11:32:04 guenther 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 #include "ssherr.h"
83
84 /* from ssh.c */
85 extern int tty_flag;
86 extern Options options;
87 extern int stdin_null_flag;
88 extern char *host;
89 extern int subsystem_flag;
90 extern Buffer command;
91 extern volatile sig_atomic_t quit_pending;
92
93 /* Context for session open confirmation callback */
94 struct mux_session_confirm_ctx {
95 u_int want_tty;
96 u_int want_subsys;
97 u_int want_x_fwd;
98 u_int want_agent_fwd;
99 Buffer cmd;
100 char *term;
101 struct termios tio;
102 char **env;
103 u_int rid;
104 };
105
106 /* Context for stdio fwd open confirmation callback */
107 struct mux_stdio_confirm_ctx {
108 u_int rid;
109 };
110
111 /* Context for global channel callback */
112 struct mux_channel_confirm_ctx {
113 u_int cid; /* channel id */
114 u_int rid; /* request id */
115 int fid; /* forward id */
116 };
117
118 /* fd to control socket */
119 int muxserver_sock = -1;
120
121 /* client request id */
122 u_int muxclient_request_id = 0;
123
124 /* Multiplexing control command */
125 u_int muxclient_command = 0;
126
127 /* Set when signalled. */
128 static volatile sig_atomic_t muxclient_terminate = 0;
129
130 /* PID of multiplex server */
131 static u_int muxserver_pid = 0;
132
133 static Channel *mux_listener_channel = NULL;
134
135 struct mux_master_state {
136 int hello_rcvd;
137 };
138
139 /* mux protocol messages */
140 #define MUX_MSG_HELLO 0x00000001
141 #define MUX_C_NEW_SESSION 0x10000002
142 #define MUX_C_ALIVE_CHECK 0x10000004
143 #define MUX_C_TERMINATE 0x10000005
144 #define MUX_C_OPEN_FWD 0x10000006
145 #define MUX_C_CLOSE_FWD 0x10000007
146 #define MUX_C_NEW_STDIO_FWD 0x10000008
147 #define MUX_C_STOP_LISTENING 0x10000009
148 #define MUX_C_PROXY 0x1000000f
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 #define MUX_S_PROXY 0x8000000f
158
159 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
160 #define MUX_FWD_LOCAL 1
161 #define MUX_FWD_REMOTE 2
162 #define MUX_FWD_DYNAMIC 3
163
164 static void mux_session_confirm(int, int, void *);
165 static void mux_stdio_confirm(int, int, void *);
166
167 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *);
168 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *);
169 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *);
170 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *);
171 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *);
172 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *);
173 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *);
174 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *);
175 static int process_mux_proxy(u_int, Channel *, Buffer *, Buffer *);
176
177 static const struct {
178 u_int type;
179 int (*handler)(u_int, Channel *, Buffer *, Buffer *);
180 } mux_master_handlers[] = {
181 { MUX_MSG_HELLO, process_mux_master_hello },
182 { MUX_C_NEW_SESSION, process_mux_new_session },
183 { MUX_C_ALIVE_CHECK, process_mux_alive_check },
184 { MUX_C_TERMINATE, process_mux_terminate },
185 { MUX_C_OPEN_FWD, process_mux_open_fwd },
186 { MUX_C_CLOSE_FWD, process_mux_close_fwd },
187 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd },
188 { MUX_C_STOP_LISTENING, process_mux_stop_listening },
189 { MUX_C_PROXY, process_mux_proxy },
190 { 0, NULL }
191 };
192
193 /* Cleanup callback fired on closure of mux slave _session_ channel */
194 /* ARGSUSED */
195 static void
mux_master_session_cleanup_cb(int cid,void * unused)196 mux_master_session_cleanup_cb(int cid, void *unused)
197 {
198 Channel *cc, *c = channel_by_id(cid);
199
200 debug3("%s: entering for channel %d", __func__, cid);
201 if (c == NULL)
202 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
203 if (c->ctl_chan != -1) {
204 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
205 fatal("%s: channel %d missing control channel %d",
206 __func__, c->self, c->ctl_chan);
207 c->ctl_chan = -1;
208 cc->remote_id = -1;
209 chan_rcvd_oclose(cc);
210 }
211 channel_cancel_cleanup(c->self);
212 }
213
214 /* Cleanup callback fired on closure of mux slave _control_ channel */
215 /* ARGSUSED */
216 static void
mux_master_control_cleanup_cb(int cid,void * unused)217 mux_master_control_cleanup_cb(int cid, void *unused)
218 {
219 Channel *sc, *c = channel_by_id(cid);
220
221 debug3("%s: entering for channel %d", __func__, cid);
222 if (c == NULL)
223 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
224 if (c->remote_id != -1) {
225 if ((sc = channel_by_id(c->remote_id)) == NULL)
226 fatal("%s: channel %d missing session channel %d",
227 __func__, c->self, c->remote_id);
228 c->remote_id = -1;
229 sc->ctl_chan = -1;
230 if (sc->type != SSH_CHANNEL_OPEN &&
231 sc->type != SSH_CHANNEL_OPENING) {
232 debug2("%s: channel %d: not open", __func__, sc->self);
233 chan_mark_dead(sc);
234 } else {
235 if (sc->istate == CHAN_INPUT_OPEN)
236 chan_read_failed(sc);
237 if (sc->ostate == CHAN_OUTPUT_OPEN)
238 chan_write_failed(sc);
239 }
240 }
241 channel_cancel_cleanup(c->self);
242 }
243
244 /* Check mux client environment variables before passing them to mux master. */
245 static int
env_permitted(char * env)246 env_permitted(char *env)
247 {
248 int i, ret;
249 char name[1024], *cp;
250
251 if ((cp = strchr(env, '=')) == NULL || cp == env)
252 return 0;
253 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
254 if (ret <= 0 || (size_t)ret >= sizeof(name)) {
255 error("env_permitted: name '%.100s...' too long", env);
256 return 0;
257 }
258
259 for (i = 0; i < options.num_send_env; i++)
260 if (match_pattern(name, options.send_env[i]))
261 return 1;
262
263 return 0;
264 }
265
266 /* Mux master protocol message handlers */
267
268 static int
process_mux_master_hello(u_int rid,Channel * c,Buffer * m,Buffer * r)269 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r)
270 {
271 u_int ver;
272 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
273
274 if (state == NULL)
275 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self);
276 if (state->hello_rcvd) {
277 error("%s: HELLO received twice", __func__);
278 return -1;
279 }
280 if (buffer_get_int_ret(&ver, m) != 0) {
281 malf:
282 error("%s: malformed message", __func__);
283 return -1;
284 }
285 if (ver != SSHMUX_VER) {
286 error("Unsupported multiplexing protocol version %d "
287 "(expected %d)", ver, SSHMUX_VER);
288 return -1;
289 }
290 debug2("%s: channel %d slave version %u", __func__, c->self, ver);
291
292 /* No extensions are presently defined */
293 while (buffer_len(m) > 0) {
294 char *name = buffer_get_string_ret(m, NULL);
295 char *value = buffer_get_string_ret(m, NULL);
296
297 if (name == NULL || value == NULL) {
298 free(name);
299 free(value);
300 goto malf;
301 }
302 debug2("Unrecognised slave extension \"%s\"", name);
303 free(name);
304 free(value);
305 }
306 state->hello_rcvd = 1;
307 return 0;
308 }
309
310 static int
process_mux_new_session(u_int rid,Channel * c,Buffer * m,Buffer * r)311 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
312 {
313 Channel *nc;
314 struct mux_session_confirm_ctx *cctx;
315 char *reserved, *cmd, *cp;
316 u_int i, j, len, env_len, escape_char, window, packetmax;
317 int new_fd[3];
318
319 /* Reply for SSHMUX_COMMAND_OPEN */
320 cctx = xcalloc(1, sizeof(*cctx));
321 cctx->term = NULL;
322 cctx->rid = rid;
323 cmd = reserved = NULL;
324 cctx->env = NULL;
325 env_len = 0;
326 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
327 buffer_get_int_ret(&cctx->want_tty, m) != 0 ||
328 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 ||
329 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 ||
330 buffer_get_int_ret(&cctx->want_subsys, m) != 0 ||
331 buffer_get_int_ret(&escape_char, m) != 0 ||
332 (cctx->term = buffer_get_string_ret(m, &len)) == NULL ||
333 (cmd = buffer_get_string_ret(m, &len)) == NULL) {
334 malf:
335 free(cmd);
336 free(reserved);
337 for (j = 0; j < env_len; j++)
338 free(cctx->env[j]);
339 free(cctx->env);
340 free(cctx->term);
341 free(cctx);
342 error("%s: malformed message", __func__);
343 return -1;
344 }
345 free(reserved);
346 reserved = NULL;
347
348 while (buffer_len(m) > 0) {
349 #define MUX_MAX_ENV_VARS 4096
350 if ((cp = buffer_get_string_ret(m, &len)) == NULL)
351 goto malf;
352 if (!env_permitted(cp)) {
353 free(cp);
354 continue;
355 }
356 cctx->env = xreallocarray(cctx->env, env_len + 2,
357 sizeof(*cctx->env));
358 cctx->env[env_len++] = cp;
359 cctx->env[env_len] = NULL;
360 if (env_len > MUX_MAX_ENV_VARS) {
361 error(">%d environment variables received, ignoring "
362 "additional", MUX_MAX_ENV_VARS);
363 break;
364 }
365 }
366
367 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, "
368 "term \"%s\", cmd \"%s\", env %u", __func__, c->self,
369 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
370 cctx->want_subsys, cctx->term, cmd, env_len);
371
372 buffer_init(&cctx->cmd);
373 buffer_append(&cctx->cmd, cmd, strlen(cmd));
374 free(cmd);
375 cmd = NULL;
376
377 /* Gather fds from client */
378 for(i = 0; i < 3; i++) {
379 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
380 error("%s: failed to receive fd %d from slave",
381 __func__, i);
382 for (j = 0; j < i; j++)
383 close(new_fd[j]);
384 for (j = 0; j < env_len; j++)
385 free(cctx->env[j]);
386 free(cctx->env);
387 free(cctx->term);
388 buffer_free(&cctx->cmd);
389 free(cctx);
390
391 /* prepare reply */
392 buffer_put_int(r, MUX_S_FAILURE);
393 buffer_put_int(r, rid);
394 buffer_put_cstring(r,
395 "did not receive file descriptors");
396 return -1;
397 }
398 }
399
400 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
401 new_fd[0], new_fd[1], new_fd[2]);
402
403 /* XXX support multiple child sessions in future */
404 if (c->remote_id != -1) {
405 debug2("%s: session already open", __func__);
406 /* prepare reply */
407 buffer_put_int(r, MUX_S_FAILURE);
408 buffer_put_int(r, rid);
409 buffer_put_cstring(r, "Multiple sessions not supported");
410 cleanup:
411 close(new_fd[0]);
412 close(new_fd[1]);
413 close(new_fd[2]);
414 free(cctx->term);
415 if (env_len != 0) {
416 for (i = 0; i < env_len; i++)
417 free(cctx->env[i]);
418 free(cctx->env);
419 }
420 buffer_free(&cctx->cmd);
421 free(cctx);
422 return 0;
423 }
424
425 if (options.control_master == SSHCTL_MASTER_ASK ||
426 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
427 if (!ask_permission("Allow shared connection to %s? ", host)) {
428 debug2("%s: session refused by user", __func__);
429 /* prepare reply */
430 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
431 buffer_put_int(r, rid);
432 buffer_put_cstring(r, "Permission denied");
433 goto cleanup;
434 }
435 }
436
437 /* Try to pick up ttymodes from client before it goes raw */
438 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
439 error("%s: tcgetattr: %s", __func__, strerror(errno));
440
441 /* enable nonblocking unless tty */
442 if (!isatty(new_fd[0]))
443 set_nonblock(new_fd[0]);
444 if (!isatty(new_fd[1]))
445 set_nonblock(new_fd[1]);
446 if (!isatty(new_fd[2]))
447 set_nonblock(new_fd[2]);
448
449 window = CHAN_SES_WINDOW_DEFAULT;
450 packetmax = CHAN_SES_PACKET_DEFAULT;
451 if (cctx->want_tty) {
452 window >>= 1;
453 packetmax >>= 1;
454 }
455
456 nc = channel_new("session", SSH_CHANNEL_OPENING,
457 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
458 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
459
460 nc->ctl_chan = c->self; /* link session -> control channel */
461 c->remote_id = nc->self; /* link control -> session channel */
462
463 if (cctx->want_tty && escape_char != 0xffffffff) {
464 channel_register_filter(nc->self,
465 client_simple_escape_filter, NULL,
466 client_filter_cleanup,
467 client_new_escape_filter_ctx((int)escape_char));
468 }
469
470 debug2("%s: channel_new: %d linked to control channel %d",
471 __func__, nc->self, nc->ctl_chan);
472
473 channel_send_open(nc->self);
474 channel_register_open_confirm(nc->self, mux_session_confirm, cctx);
475 c->mux_pause = 1; /* stop handling messages until open_confirm done */
476 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
477
478 /* reply is deferred, sent by mux_session_confirm */
479 return 0;
480 }
481
482 static int
process_mux_alive_check(u_int rid,Channel * c,Buffer * m,Buffer * r)483 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r)
484 {
485 debug2("%s: channel %d: alive check", __func__, c->self);
486
487 /* prepare reply */
488 buffer_put_int(r, MUX_S_ALIVE);
489 buffer_put_int(r, rid);
490 buffer_put_int(r, (u_int)getpid());
491
492 return 0;
493 }
494
495 static int
process_mux_terminate(u_int rid,Channel * c,Buffer * m,Buffer * r)496 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r)
497 {
498 debug2("%s: channel %d: terminate request", __func__, c->self);
499
500 if (options.control_master == SSHCTL_MASTER_ASK ||
501 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
502 if (!ask_permission("Terminate shared connection to %s? ",
503 host)) {
504 debug2("%s: termination refused by user", __func__);
505 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
506 buffer_put_int(r, rid);
507 buffer_put_cstring(r, "Permission denied");
508 return 0;
509 }
510 }
511
512 quit_pending = 1;
513 buffer_put_int(r, MUX_S_OK);
514 buffer_put_int(r, rid);
515 /* XXX exit happens too soon - message never makes it to client */
516 return 0;
517 }
518
519 static char *
format_forward(u_int ftype,struct Forward * fwd)520 format_forward(u_int ftype, struct Forward *fwd)
521 {
522 char *ret;
523
524 switch (ftype) {
525 case MUX_FWD_LOCAL:
526 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
527 (fwd->listen_path != NULL) ? fwd->listen_path :
528 (fwd->listen_host == NULL) ?
529 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
530 fwd->listen_host, fwd->listen_port,
531 (fwd->connect_path != NULL) ? fwd->connect_path :
532 fwd->connect_host, fwd->connect_port);
533 break;
534 case MUX_FWD_DYNAMIC:
535 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
536 (fwd->listen_host == NULL) ?
537 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
538 fwd->listen_host, fwd->listen_port);
539 break;
540 case MUX_FWD_REMOTE:
541 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
542 (fwd->listen_path != NULL) ? fwd->listen_path :
543 (fwd->listen_host == NULL) ?
544 "LOCALHOST" : fwd->listen_host,
545 fwd->listen_port,
546 (fwd->connect_path != NULL) ? fwd->connect_path :
547 fwd->connect_host, fwd->connect_port);
548 break;
549 default:
550 fatal("%s: unknown forward type %u", __func__, ftype);
551 }
552 return ret;
553 }
554
555 static int
compare_host(const char * a,const char * b)556 compare_host(const char *a, const char *b)
557 {
558 if (a == NULL && b == NULL)
559 return 1;
560 if (a == NULL || b == NULL)
561 return 0;
562 return strcmp(a, b) == 0;
563 }
564
565 static int
compare_forward(struct Forward * a,struct Forward * b)566 compare_forward(struct Forward *a, struct Forward *b)
567 {
568 if (!compare_host(a->listen_host, b->listen_host))
569 return 0;
570 if (!compare_host(a->listen_path, b->listen_path))
571 return 0;
572 if (a->listen_port != b->listen_port)
573 return 0;
574 if (!compare_host(a->connect_host, b->connect_host))
575 return 0;
576 if (!compare_host(a->connect_path, b->connect_path))
577 return 0;
578 if (a->connect_port != b->connect_port)
579 return 0;
580
581 return 1;
582 }
583
584 static void
mux_confirm_remote_forward(int type,u_int32_t seq,void * ctxt)585 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
586 {
587 struct mux_channel_confirm_ctx *fctx = ctxt;
588 char *failmsg = NULL;
589 struct Forward *rfwd;
590 Channel *c;
591 Buffer out;
592
593 if ((c = channel_by_id(fctx->cid)) == NULL) {
594 /* no channel for reply */
595 error("%s: unknown channel", __func__);
596 return;
597 }
598 buffer_init(&out);
599 if (fctx->fid >= options.num_remote_forwards ||
600 (options.remote_forwards[fctx->fid].connect_path == NULL &&
601 options.remote_forwards[fctx->fid].connect_host == NULL)) {
602 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
603 goto fail;
604 }
605 rfwd = &options.remote_forwards[fctx->fid];
606 debug("%s: %s for: listen %d, connect %s:%d", __func__,
607 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
608 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
609 rfwd->connect_host, rfwd->connect_port);
610 if (type == SSH2_MSG_REQUEST_SUCCESS) {
611 if (rfwd->listen_port == 0) {
612 rfwd->allocated_port = packet_get_int();
613 debug("Allocated port %u for mux remote forward"
614 " to %s:%d", rfwd->allocated_port,
615 rfwd->connect_host, rfwd->connect_port);
616 buffer_put_int(&out, MUX_S_REMOTE_PORT);
617 buffer_put_int(&out, fctx->rid);
618 buffer_put_int(&out, rfwd->allocated_port);
619 channel_update_permitted_opens(rfwd->handle,
620 rfwd->allocated_port);
621 } else {
622 buffer_put_int(&out, MUX_S_OK);
623 buffer_put_int(&out, fctx->rid);
624 }
625 goto out;
626 } else {
627 if (rfwd->listen_port == 0)
628 channel_update_permitted_opens(rfwd->handle, -1);
629 if (rfwd->listen_path != NULL)
630 xasprintf(&failmsg, "remote port forwarding failed for "
631 "listen path %s", rfwd->listen_path);
632 else
633 xasprintf(&failmsg, "remote port forwarding failed for "
634 "listen port %d", rfwd->listen_port);
635
636 debug2("%s: clearing registered forwarding for listen %d, "
637 "connect %s:%d", __func__, rfwd->listen_port,
638 rfwd->connect_path ? rfwd->connect_path :
639 rfwd->connect_host, rfwd->connect_port);
640
641 free(rfwd->listen_host);
642 free(rfwd->listen_path);
643 free(rfwd->connect_host);
644 free(rfwd->connect_path);
645 memset(rfwd, 0, sizeof(*rfwd));
646 }
647 fail:
648 error("%s: %s", __func__, failmsg);
649 buffer_put_int(&out, MUX_S_FAILURE);
650 buffer_put_int(&out, fctx->rid);
651 buffer_put_cstring(&out, failmsg);
652 free(failmsg);
653 out:
654 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out));
655 buffer_free(&out);
656 if (c->mux_pause <= 0)
657 fatal("%s: mux_pause %d", __func__, c->mux_pause);
658 c->mux_pause = 0; /* start processing messages again */
659 }
660
661 static int
process_mux_open_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)662 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
663 {
664 struct Forward fwd;
665 char *fwd_desc = NULL;
666 char *listen_addr, *connect_addr;
667 u_int ftype;
668 u_int lport, cport;
669 int i, ret = 0, freefwd = 1;
670
671 memset(&fwd, 0, sizeof(fwd));
672
673 /* XXX - lport/cport check redundant */
674 if (buffer_get_int_ret(&ftype, m) != 0 ||
675 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL ||
676 buffer_get_int_ret(&lport, m) != 0 ||
677 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL ||
678 buffer_get_int_ret(&cport, m) != 0 ||
679 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
680 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
681 error("%s: malformed message", __func__);
682 ret = -1;
683 goto out;
684 }
685 if (*listen_addr == '\0') {
686 free(listen_addr);
687 listen_addr = NULL;
688 }
689 if (*connect_addr == '\0') {
690 free(connect_addr);
691 connect_addr = NULL;
692 }
693
694 memset(&fwd, 0, sizeof(fwd));
695 fwd.listen_port = lport;
696 if (fwd.listen_port == PORT_STREAMLOCAL)
697 fwd.listen_path = listen_addr;
698 else
699 fwd.listen_host = listen_addr;
700 fwd.connect_port = cport;
701 if (fwd.connect_port == PORT_STREAMLOCAL)
702 fwd.connect_path = connect_addr;
703 else
704 fwd.connect_host = connect_addr;
705
706 debug2("%s: channel %d: request %s", __func__, c->self,
707 (fwd_desc = format_forward(ftype, &fwd)));
708
709 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
710 ftype != MUX_FWD_DYNAMIC) {
711 logit("%s: invalid forwarding type %u", __func__, ftype);
712 invalid:
713 free(listen_addr);
714 free(connect_addr);
715 buffer_put_int(r, MUX_S_FAILURE);
716 buffer_put_int(r, rid);
717 buffer_put_cstring(r, "Invalid forwarding request");
718 return 0;
719 }
720 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) {
721 logit("%s: streamlocal and dynamic forwards "
722 "are mutually exclusive", __func__);
723 goto invalid;
724 }
725 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) {
726 logit("%s: invalid listen port %u", __func__,
727 fwd.listen_port);
728 goto invalid;
729 }
730 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536)
731 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) {
732 logit("%s: invalid connect port %u", __func__,
733 fwd.connect_port);
734 goto invalid;
735 }
736 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) {
737 logit("%s: missing connect host", __func__);
738 goto invalid;
739 }
740
741 /* Skip forwards that have already been requested */
742 switch (ftype) {
743 case MUX_FWD_LOCAL:
744 case MUX_FWD_DYNAMIC:
745 for (i = 0; i < options.num_local_forwards; i++) {
746 if (compare_forward(&fwd,
747 options.local_forwards + i)) {
748 exists:
749 debug2("%s: found existing forwarding",
750 __func__);
751 buffer_put_int(r, MUX_S_OK);
752 buffer_put_int(r, rid);
753 goto out;
754 }
755 }
756 break;
757 case MUX_FWD_REMOTE:
758 for (i = 0; i < options.num_remote_forwards; i++) {
759 if (compare_forward(&fwd,
760 options.remote_forwards + i)) {
761 if (fwd.listen_port != 0)
762 goto exists;
763 debug2("%s: found allocated port",
764 __func__);
765 buffer_put_int(r, MUX_S_REMOTE_PORT);
766 buffer_put_int(r, rid);
767 buffer_put_int(r,
768 options.remote_forwards[i].allocated_port);
769 goto out;
770 }
771 }
772 break;
773 }
774
775 if (options.control_master == SSHCTL_MASTER_ASK ||
776 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
777 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
778 debug2("%s: forwarding refused by user", __func__);
779 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
780 buffer_put_int(r, rid);
781 buffer_put_cstring(r, "Permission denied");
782 goto out;
783 }
784 }
785
786 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
787 if (!channel_setup_local_fwd_listener(&fwd,
788 &options.fwd_opts)) {
789 fail:
790 logit("slave-requested %s failed", fwd_desc);
791 buffer_put_int(r, MUX_S_FAILURE);
792 buffer_put_int(r, rid);
793 buffer_put_cstring(r, "Port forwarding failed");
794 goto out;
795 }
796 add_local_forward(&options, &fwd);
797 freefwd = 0;
798 } else {
799 struct mux_channel_confirm_ctx *fctx;
800
801 fwd.handle = channel_request_remote_forwarding(&fwd);
802 if (fwd.handle < 0)
803 goto fail;
804 add_remote_forward(&options, &fwd);
805 fctx = xcalloc(1, sizeof(*fctx));
806 fctx->cid = c->self;
807 fctx->rid = rid;
808 fctx->fid = options.num_remote_forwards - 1;
809 client_register_global_confirm(mux_confirm_remote_forward,
810 fctx);
811 freefwd = 0;
812 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
813 /* delayed reply in mux_confirm_remote_forward */
814 goto out;
815 }
816 buffer_put_int(r, MUX_S_OK);
817 buffer_put_int(r, rid);
818 out:
819 free(fwd_desc);
820 if (freefwd) {
821 free(fwd.listen_host);
822 free(fwd.listen_path);
823 free(fwd.connect_host);
824 free(fwd.connect_path);
825 }
826 return ret;
827 }
828
829 static int
process_mux_close_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)830 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
831 {
832 struct Forward fwd, *found_fwd;
833 char *fwd_desc = NULL;
834 const char *error_reason = NULL;
835 char *listen_addr = NULL, *connect_addr = NULL;
836 u_int ftype;
837 int i, ret = 0;
838 u_int lport, cport;
839
840 memset(&fwd, 0, sizeof(fwd));
841
842 if (buffer_get_int_ret(&ftype, m) != 0 ||
843 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL ||
844 buffer_get_int_ret(&lport, m) != 0 ||
845 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL ||
846 buffer_get_int_ret(&cport, m) != 0 ||
847 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
848 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
849 error("%s: malformed message", __func__);
850 ret = -1;
851 goto out;
852 }
853
854 if (*listen_addr == '\0') {
855 free(listen_addr);
856 listen_addr = NULL;
857 }
858 if (*connect_addr == '\0') {
859 free(connect_addr);
860 connect_addr = NULL;
861 }
862
863 memset(&fwd, 0, sizeof(fwd));
864 fwd.listen_port = lport;
865 if (fwd.listen_port == PORT_STREAMLOCAL)
866 fwd.listen_path = listen_addr;
867 else
868 fwd.listen_host = listen_addr;
869 fwd.connect_port = cport;
870 if (fwd.connect_port == PORT_STREAMLOCAL)
871 fwd.connect_path = connect_addr;
872 else
873 fwd.connect_host = connect_addr;
874
875 debug2("%s: channel %d: request cancel %s", __func__, c->self,
876 (fwd_desc = format_forward(ftype, &fwd)));
877
878 /* make sure this has been requested */
879 found_fwd = NULL;
880 switch (ftype) {
881 case MUX_FWD_LOCAL:
882 case MUX_FWD_DYNAMIC:
883 for (i = 0; i < options.num_local_forwards; i++) {
884 if (compare_forward(&fwd,
885 options.local_forwards + i)) {
886 found_fwd = options.local_forwards + i;
887 break;
888 }
889 }
890 break;
891 case MUX_FWD_REMOTE:
892 for (i = 0; i < options.num_remote_forwards; i++) {
893 if (compare_forward(&fwd,
894 options.remote_forwards + i)) {
895 found_fwd = options.remote_forwards + i;
896 break;
897 }
898 }
899 break;
900 }
901
902 if (found_fwd == NULL)
903 error_reason = "port not forwarded";
904 else if (ftype == MUX_FWD_REMOTE) {
905 /*
906 * This shouldn't fail unless we confused the host/port
907 * between options.remote_forwards and permitted_opens.
908 * However, for dynamic allocated listen ports we need
909 * to use the actual listen port.
910 */
911 if (channel_request_rforward_cancel(found_fwd) == -1)
912 error_reason = "port not in permitted opens";
913 } else { /* local and dynamic forwards */
914 /* Ditto */
915 if (channel_cancel_lport_listener(&fwd, fwd.connect_port,
916 &options.fwd_opts) == -1)
917 error_reason = "port not found";
918 }
919
920 if (error_reason == NULL) {
921 buffer_put_int(r, MUX_S_OK);
922 buffer_put_int(r, rid);
923
924 free(found_fwd->listen_host);
925 free(found_fwd->listen_path);
926 free(found_fwd->connect_host);
927 free(found_fwd->connect_path);
928 found_fwd->listen_host = found_fwd->connect_host = NULL;
929 found_fwd->listen_path = found_fwd->connect_path = NULL;
930 found_fwd->listen_port = found_fwd->connect_port = 0;
931 } else {
932 buffer_put_int(r, MUX_S_FAILURE);
933 buffer_put_int(r, rid);
934 buffer_put_cstring(r, error_reason);
935 }
936 out:
937 free(fwd_desc);
938 free(listen_addr);
939 free(connect_addr);
940
941 return ret;
942 }
943
944 static int
process_mux_stdio_fwd(u_int rid,Channel * c,Buffer * m,Buffer * r)945 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
946 {
947 Channel *nc;
948 char *reserved, *chost;
949 u_int cport, i, j;
950 int new_fd[2];
951 struct mux_stdio_confirm_ctx *cctx;
952
953 chost = reserved = NULL;
954 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL ||
955 (chost = buffer_get_string_ret(m, NULL)) == NULL ||
956 buffer_get_int_ret(&cport, m) != 0) {
957 free(reserved);
958 free(chost);
959 error("%s: malformed message", __func__);
960 return -1;
961 }
962 free(reserved);
963
964 debug2("%s: channel %d: request stdio fwd to %s:%u",
965 __func__, c->self, chost, cport);
966
967 /* Gather fds from client */
968 for(i = 0; i < 2; i++) {
969 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
970 error("%s: failed to receive fd %d from slave",
971 __func__, i);
972 for (j = 0; j < i; j++)
973 close(new_fd[j]);
974 free(chost);
975
976 /* prepare reply */
977 buffer_put_int(r, MUX_S_FAILURE);
978 buffer_put_int(r, rid);
979 buffer_put_cstring(r,
980 "did not receive file descriptors");
981 return -1;
982 }
983 }
984
985 debug3("%s: got fds stdin %d, stdout %d", __func__,
986 new_fd[0], new_fd[1]);
987
988 /* XXX support multiple child sessions in future */
989 if (c->remote_id != -1) {
990 debug2("%s: session already open", __func__);
991 /* prepare reply */
992 buffer_put_int(r, MUX_S_FAILURE);
993 buffer_put_int(r, rid);
994 buffer_put_cstring(r, "Multiple sessions not supported");
995 cleanup:
996 close(new_fd[0]);
997 close(new_fd[1]);
998 free(chost);
999 return 0;
1000 }
1001
1002 if (options.control_master == SSHCTL_MASTER_ASK ||
1003 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1004 if (!ask_permission("Allow forward to %s:%u? ",
1005 chost, cport)) {
1006 debug2("%s: stdio fwd refused by user", __func__);
1007 /* prepare reply */
1008 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
1009 buffer_put_int(r, rid);
1010 buffer_put_cstring(r, "Permission denied");
1011 goto cleanup;
1012 }
1013 }
1014
1015 /* enable nonblocking unless tty */
1016 if (!isatty(new_fd[0]))
1017 set_nonblock(new_fd[0]);
1018 if (!isatty(new_fd[1]))
1019 set_nonblock(new_fd[1]);
1020
1021 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]);
1022
1023 nc->ctl_chan = c->self; /* link session -> control channel */
1024 c->remote_id = nc->self; /* link control -> session channel */
1025
1026 debug2("%s: channel_new: %d linked to control channel %d",
1027 __func__, nc->self, nc->ctl_chan);
1028
1029 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
1030
1031 cctx = xcalloc(1, sizeof(*cctx));
1032 cctx->rid = rid;
1033 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx);
1034 c->mux_pause = 1; /* stop handling messages until open_confirm done */
1035
1036 /* reply is deferred, sent by mux_session_confirm */
1037 return 0;
1038 }
1039
1040 /* Callback on open confirmation in mux master for a mux stdio fwd session. */
1041 static void
mux_stdio_confirm(int id,int success,void * arg)1042 mux_stdio_confirm(int id, int success, void *arg)
1043 {
1044 struct mux_stdio_confirm_ctx *cctx = arg;
1045 Channel *c, *cc;
1046 Buffer reply;
1047
1048 if (cctx == NULL)
1049 fatal("%s: cctx == NULL", __func__);
1050 if ((c = channel_by_id(id)) == NULL)
1051 fatal("%s: no channel for id %d", __func__, id);
1052 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
1053 fatal("%s: channel %d lacks control channel %d", __func__,
1054 id, c->ctl_chan);
1055
1056 if (!success) {
1057 debug3("%s: sending failure reply", __func__);
1058 /* prepare reply */
1059 buffer_init(&reply);
1060 buffer_put_int(&reply, MUX_S_FAILURE);
1061 buffer_put_int(&reply, cctx->rid);
1062 buffer_put_cstring(&reply, "Session open refused by peer");
1063 goto done;
1064 }
1065
1066 debug3("%s: sending success reply", __func__);
1067 /* prepare reply */
1068 buffer_init(&reply);
1069 buffer_put_int(&reply, MUX_S_SESSION_OPENED);
1070 buffer_put_int(&reply, cctx->rid);
1071 buffer_put_int(&reply, c->self);
1072
1073 done:
1074 /* Send reply */
1075 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
1076 buffer_free(&reply);
1077
1078 if (cc->mux_pause <= 0)
1079 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1080 cc->mux_pause = 0; /* start processing messages again */
1081 c->open_confirm_ctx = NULL;
1082 free(cctx);
1083 }
1084
1085 static int
process_mux_stop_listening(u_int rid,Channel * c,Buffer * m,Buffer * r)1086 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
1087 {
1088 debug("%s: channel %d: stop listening", __func__, c->self);
1089
1090 if (options.control_master == SSHCTL_MASTER_ASK ||
1091 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1092 if (!ask_permission("Disable further multiplexing on shared "
1093 "connection to %s? ", host)) {
1094 debug2("%s: stop listen refused by user", __func__);
1095 buffer_put_int(r, MUX_S_PERMISSION_DENIED);
1096 buffer_put_int(r, rid);
1097 buffer_put_cstring(r, "Permission denied");
1098 return 0;
1099 }
1100 }
1101
1102 if (mux_listener_channel != NULL) {
1103 channel_free(mux_listener_channel);
1104 client_stop_mux();
1105 free(options.control_path);
1106 options.control_path = NULL;
1107 mux_listener_channel = NULL;
1108 muxserver_sock = -1;
1109 }
1110
1111 /* prepare reply */
1112 buffer_put_int(r, MUX_S_OK);
1113 buffer_put_int(r, rid);
1114
1115 return 0;
1116 }
1117
1118 static int
process_mux_proxy(u_int rid,Channel * c,Buffer * m,Buffer * r)1119 process_mux_proxy(u_int rid, Channel *c, Buffer *m, Buffer *r)
1120 {
1121 debug("%s: channel %d: proxy request", __func__, c->self);
1122
1123 c->mux_rcb = channel_proxy_downstream;
1124 buffer_put_int(r, MUX_S_PROXY);
1125 buffer_put_int(r, rid);
1126
1127 return 0;
1128 }
1129
1130 /* Channel callbacks fired on read/write from mux slave fd */
1131 static int
mux_master_read_cb(Channel * c)1132 mux_master_read_cb(Channel *c)
1133 {
1134 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
1135 Buffer in, out;
1136 const u_char *ptr;
1137 u_int type, rid, have, i;
1138 int ret = -1;
1139
1140 /* Setup ctx and */
1141 if (c->mux_ctx == NULL) {
1142 state = xcalloc(1, sizeof(*state));
1143 c->mux_ctx = state;
1144 channel_register_cleanup(c->self,
1145 mux_master_control_cleanup_cb, 0);
1146
1147 /* Send hello */
1148 buffer_init(&out);
1149 buffer_put_int(&out, MUX_MSG_HELLO);
1150 buffer_put_int(&out, SSHMUX_VER);
1151 /* no extensions */
1152 buffer_put_string(&c->output, buffer_ptr(&out),
1153 buffer_len(&out));
1154 buffer_free(&out);
1155 debug3("%s: channel %d: hello sent", __func__, c->self);
1156 return 0;
1157 }
1158
1159 buffer_init(&in);
1160 buffer_init(&out);
1161
1162 /* Channel code ensures that we receive whole packets */
1163 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) {
1164 malf:
1165 error("%s: malformed message", __func__);
1166 goto out;
1167 }
1168 buffer_append(&in, ptr, have);
1169
1170 if (buffer_get_int_ret(&type, &in) != 0)
1171 goto malf;
1172 debug3("%s: channel %d packet type 0x%08x len %u",
1173 __func__, c->self, type, buffer_len(&in));
1174
1175 if (type == MUX_MSG_HELLO)
1176 rid = 0;
1177 else {
1178 if (!state->hello_rcvd) {
1179 error("%s: expected MUX_MSG_HELLO(0x%08x), "
1180 "received 0x%08x", __func__, MUX_MSG_HELLO, type);
1181 goto out;
1182 }
1183 if (buffer_get_int_ret(&rid, &in) != 0)
1184 goto malf;
1185 }
1186
1187 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
1188 if (type == mux_master_handlers[i].type) {
1189 ret = mux_master_handlers[i].handler(rid, c, &in, &out);
1190 break;
1191 }
1192 }
1193 if (mux_master_handlers[i].handler == NULL) {
1194 error("%s: unsupported mux message 0x%08x", __func__, type);
1195 buffer_put_int(&out, MUX_S_FAILURE);
1196 buffer_put_int(&out, rid);
1197 buffer_put_cstring(&out, "unsupported request");
1198 ret = 0;
1199 }
1200 /* Enqueue reply packet */
1201 if (buffer_len(&out) != 0) {
1202 buffer_put_string(&c->output, buffer_ptr(&out),
1203 buffer_len(&out));
1204 }
1205 out:
1206 buffer_free(&in);
1207 buffer_free(&out);
1208 return ret;
1209 }
1210
1211 void
mux_exit_message(Channel * c,int exitval)1212 mux_exit_message(Channel *c, int exitval)
1213 {
1214 Buffer m;
1215 Channel *mux_chan;
1216
1217 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self,
1218 exitval);
1219
1220 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
1221 fatal("%s: channel %d missing mux channel %d",
1222 __func__, c->self, c->ctl_chan);
1223
1224 /* Append exit message packet to control socket output queue */
1225 buffer_init(&m);
1226 buffer_put_int(&m, MUX_S_EXIT_MESSAGE);
1227 buffer_put_int(&m, c->self);
1228 buffer_put_int(&m, exitval);
1229
1230 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
1231 buffer_free(&m);
1232 }
1233
1234 void
mux_tty_alloc_failed(Channel * c)1235 mux_tty_alloc_failed(Channel *c)
1236 {
1237 Buffer m;
1238 Channel *mux_chan;
1239
1240 debug3("%s: channel %d: TTY alloc failed", __func__, c->self);
1241
1242 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
1243 fatal("%s: channel %d missing mux channel %d",
1244 __func__, c->self, c->ctl_chan);
1245
1246 /* Append exit message packet to control socket output queue */
1247 buffer_init(&m);
1248 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL);
1249 buffer_put_int(&m, c->self);
1250
1251 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
1252 buffer_free(&m);
1253 }
1254
1255 /* Prepare a mux master to listen on a Unix domain socket. */
1256 void
muxserver_listen(void)1257 muxserver_listen(void)
1258 {
1259 mode_t old_umask;
1260 char *orig_control_path = options.control_path;
1261 char rbuf[16+1];
1262 u_int i, r;
1263 int oerrno;
1264
1265 if (options.control_path == NULL ||
1266 options.control_master == SSHCTL_MASTER_NO)
1267 return;
1268
1269 debug("setting up multiplex master socket");
1270
1271 /*
1272 * Use a temporary path before listen so we can pseudo-atomically
1273 * establish the listening socket in its final location to avoid
1274 * other processes racing in between bind() and listen() and hitting
1275 * an unready socket.
1276 */
1277 for (i = 0; i < sizeof(rbuf) - 1; i++) {
1278 r = arc4random_uniform(26+26+10);
1279 rbuf[i] = (r < 26) ? 'a' + r :
1280 (r < 26*2) ? 'A' + r - 26 :
1281 '0' + r - 26 - 26;
1282 }
1283 rbuf[sizeof(rbuf) - 1] = '\0';
1284 options.control_path = NULL;
1285 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
1286 debug3("%s: temporary control path %s", __func__, options.control_path);
1287
1288 old_umask = umask(0177);
1289 muxserver_sock = unix_listener(options.control_path, 64, 0);
1290 oerrno = errno;
1291 umask(old_umask);
1292 if (muxserver_sock < 0) {
1293 if (oerrno == EINVAL || oerrno == EADDRINUSE) {
1294 error("ControlSocket %s already exists, "
1295 "disabling multiplexing", options.control_path);
1296 disable_mux_master:
1297 if (muxserver_sock != -1) {
1298 close(muxserver_sock);
1299 muxserver_sock = -1;
1300 }
1301 free(orig_control_path);
1302 free(options.control_path);
1303 options.control_path = NULL;
1304 options.control_master = SSHCTL_MASTER_NO;
1305 return;
1306 } else {
1307 /* unix_listener() logs the error */
1308 cleanup_exit(255);
1309 }
1310 }
1311
1312 /* Now atomically "move" the mux socket into position */
1313 if (link(options.control_path, orig_control_path) != 0) {
1314 if (errno != EEXIST) {
1315 fatal("%s: link mux listener %s => %s: %s", __func__,
1316 options.control_path, orig_control_path,
1317 strerror(errno));
1318 }
1319 error("ControlSocket %s already exists, disabling multiplexing",
1320 orig_control_path);
1321 unlink(options.control_path);
1322 goto disable_mux_master;
1323 }
1324 unlink(options.control_path);
1325 free(options.control_path);
1326 options.control_path = orig_control_path;
1327
1328 set_nonblock(muxserver_sock);
1329
1330 mux_listener_channel = channel_new("mux listener",
1331 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
1332 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1333 0, options.control_path, 1);
1334 mux_listener_channel->mux_rcb = mux_master_read_cb;
1335 debug3("%s: mux listener channel %d fd %d", __func__,
1336 mux_listener_channel->self, mux_listener_channel->sock);
1337 }
1338
1339 /* Callback on open confirmation in mux master for a mux client session. */
1340 static void
mux_session_confirm(int id,int success,void * arg)1341 mux_session_confirm(int id, int success, void *arg)
1342 {
1343 struct mux_session_confirm_ctx *cctx = arg;
1344 const char *display;
1345 Channel *c, *cc;
1346 int i;
1347 Buffer reply;
1348
1349 if (cctx == NULL)
1350 fatal("%s: cctx == NULL", __func__);
1351 if ((c = channel_by_id(id)) == NULL)
1352 fatal("%s: no channel for id %d", __func__, id);
1353 if ((cc = channel_by_id(c->ctl_chan)) == NULL)
1354 fatal("%s: channel %d lacks control channel %d", __func__,
1355 id, c->ctl_chan);
1356
1357 if (!success) {
1358 debug3("%s: sending failure reply", __func__);
1359 /* prepare reply */
1360 buffer_init(&reply);
1361 buffer_put_int(&reply, MUX_S_FAILURE);
1362 buffer_put_int(&reply, cctx->rid);
1363 buffer_put_cstring(&reply, "Session open refused by peer");
1364 goto done;
1365 }
1366
1367 display = getenv("DISPLAY");
1368 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1369 char *proto, *data;
1370
1371 /* Get reasonable local authentication information. */
1372 if (client_x11_get_proto(display, options.xauth_location,
1373 options.forward_x11_trusted, options.forward_x11_timeout,
1374 &proto, &data) == 0) {
1375 /* Request forwarding with authentication spoofing. */
1376 debug("Requesting X11 forwarding with authentication "
1377 "spoofing.");
1378 x11_request_forwarding_with_spoofing(id, display, proto,
1379 data, 1);
1380 /* XXX exit_on_forward_failure */
1381 client_expect_confirm(id, "X11 forwarding",
1382 CONFIRM_WARN);
1383 }
1384 }
1385
1386 if (cctx->want_agent_fwd && options.forward_agent) {
1387 debug("Requesting authentication agent forwarding.");
1388 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1389 packet_send();
1390 }
1391
1392 client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
1393 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
1394
1395 debug3("%s: sending success reply", __func__);
1396 /* prepare reply */
1397 buffer_init(&reply);
1398 buffer_put_int(&reply, MUX_S_SESSION_OPENED);
1399 buffer_put_int(&reply, cctx->rid);
1400 buffer_put_int(&reply, c->self);
1401
1402 done:
1403 /* Send reply */
1404 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
1405 buffer_free(&reply);
1406
1407 if (cc->mux_pause <= 0)
1408 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1409 cc->mux_pause = 0; /* start processing messages again */
1410 c->open_confirm_ctx = NULL;
1411 buffer_free(&cctx->cmd);
1412 free(cctx->term);
1413 if (cctx->env != NULL) {
1414 for (i = 0; cctx->env[i] != NULL; i++)
1415 free(cctx->env[i]);
1416 free(cctx->env);
1417 }
1418 free(cctx);
1419 }
1420
1421 /* ** Multiplexing client support */
1422
1423 /* Exit signal handler */
1424 static void
control_client_sighandler(int signo)1425 control_client_sighandler(int signo)
1426 {
1427 muxclient_terminate = signo;
1428 }
1429
1430 /*
1431 * Relay signal handler - used to pass some signals from mux client to
1432 * mux master.
1433 */
1434 static void
control_client_sigrelay(int signo)1435 control_client_sigrelay(int signo)
1436 {
1437 int save_errno = errno;
1438
1439 if (muxserver_pid > 1)
1440 kill(muxserver_pid, signo);
1441
1442 errno = save_errno;
1443 }
1444
1445 static int
mux_client_read(int fd,Buffer * b,u_int need)1446 mux_client_read(int fd, Buffer *b, u_int need)
1447 {
1448 u_int have;
1449 ssize_t len;
1450 u_char *p;
1451 struct pollfd pfd;
1452
1453 pfd.fd = fd;
1454 pfd.events = POLLIN;
1455 p = buffer_append_space(b, need);
1456 for (have = 0; have < need; ) {
1457 if (muxclient_terminate) {
1458 errno = EINTR;
1459 return -1;
1460 }
1461 len = read(fd, p + have, need - have);
1462 if (len < 0) {
1463 switch (errno) {
1464 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1465 case EWOULDBLOCK:
1466 #endif
1467 case EAGAIN:
1468 (void)poll(&pfd, 1, -1);
1469 /* FALLTHROUGH */
1470 case EINTR:
1471 continue;
1472 default:
1473 return -1;
1474 }
1475 }
1476 if (len == 0) {
1477 errno = EPIPE;
1478 return -1;
1479 }
1480 have += (u_int)len;
1481 }
1482 return 0;
1483 }
1484
1485 static int
mux_client_write_packet(int fd,Buffer * m)1486 mux_client_write_packet(int fd, Buffer *m)
1487 {
1488 Buffer queue;
1489 u_int have, need;
1490 int oerrno, len;
1491 u_char *ptr;
1492 struct pollfd pfd;
1493
1494 pfd.fd = fd;
1495 pfd.events = POLLOUT;
1496 buffer_init(&queue);
1497 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m));
1498
1499 need = buffer_len(&queue);
1500 ptr = buffer_ptr(&queue);
1501
1502 for (have = 0; have < need; ) {
1503 if (muxclient_terminate) {
1504 buffer_free(&queue);
1505 errno = EINTR;
1506 return -1;
1507 }
1508 len = write(fd, ptr + have, need - have);
1509 if (len < 0) {
1510 switch (errno) {
1511 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1512 case EWOULDBLOCK:
1513 #endif
1514 case EAGAIN:
1515 (void)poll(&pfd, 1, -1);
1516 /* FALLTHROUGH */
1517 case EINTR:
1518 continue;
1519 default:
1520 oerrno = errno;
1521 buffer_free(&queue);
1522 errno = oerrno;
1523 return -1;
1524 }
1525 }
1526 if (len == 0) {
1527 buffer_free(&queue);
1528 errno = EPIPE;
1529 return -1;
1530 }
1531 have += (u_int)len;
1532 }
1533 buffer_free(&queue);
1534 return 0;
1535 }
1536
1537 static int
mux_client_read_packet(int fd,Buffer * m)1538 mux_client_read_packet(int fd, Buffer *m)
1539 {
1540 Buffer queue;
1541 u_int need, have;
1542 const u_char *ptr;
1543 int oerrno;
1544
1545 buffer_init(&queue);
1546 if (mux_client_read(fd, &queue, 4) != 0) {
1547 if ((oerrno = errno) == EPIPE)
1548 debug3("%s: read header failed: %s", __func__,
1549 strerror(errno));
1550 buffer_free(&queue);
1551 errno = oerrno;
1552 return -1;
1553 }
1554 need = get_u32(buffer_ptr(&queue));
1555 if (mux_client_read(fd, &queue, need) != 0) {
1556 oerrno = errno;
1557 debug3("%s: read body failed: %s", __func__, strerror(errno));
1558 buffer_free(&queue);
1559 errno = oerrno;
1560 return -1;
1561 }
1562 ptr = buffer_get_string_ptr(&queue, &have);
1563 buffer_append(m, ptr, have);
1564 buffer_free(&queue);
1565 return 0;
1566 }
1567
1568 static int
mux_client_hello_exchange(int fd)1569 mux_client_hello_exchange(int fd)
1570 {
1571 Buffer m;
1572 u_int type, ver;
1573
1574 buffer_init(&m);
1575 buffer_put_int(&m, MUX_MSG_HELLO);
1576 buffer_put_int(&m, SSHMUX_VER);
1577 /* no extensions */
1578
1579 if (mux_client_write_packet(fd, &m) != 0)
1580 fatal("%s: write packet: %s", __func__, strerror(errno));
1581
1582 buffer_clear(&m);
1583
1584 /* Read their HELLO */
1585 if (mux_client_read_packet(fd, &m) != 0) {
1586 buffer_free(&m);
1587 return -1;
1588 }
1589
1590 type = buffer_get_int(&m);
1591 if (type != MUX_MSG_HELLO)
1592 fatal("%s: expected HELLO (%u) received %u",
1593 __func__, MUX_MSG_HELLO, type);
1594 ver = buffer_get_int(&m);
1595 if (ver != SSHMUX_VER)
1596 fatal("Unsupported multiplexing protocol version %d "
1597 "(expected %d)", ver, SSHMUX_VER);
1598 debug2("%s: master version %u", __func__, ver);
1599 /* No extensions are presently defined */
1600 while (buffer_len(&m) > 0) {
1601 char *name = buffer_get_string(&m, NULL);
1602 char *value = buffer_get_string(&m, NULL);
1603
1604 debug2("Unrecognised master extension \"%s\"", name);
1605 free(name);
1606 free(value);
1607 }
1608 buffer_free(&m);
1609 return 0;
1610 }
1611
1612 static u_int
mux_client_request_alive(int fd)1613 mux_client_request_alive(int fd)
1614 {
1615 Buffer m;
1616 char *e;
1617 u_int pid, type, rid;
1618
1619 debug3("%s: entering", __func__);
1620
1621 buffer_init(&m);
1622 buffer_put_int(&m, MUX_C_ALIVE_CHECK);
1623 buffer_put_int(&m, muxclient_request_id);
1624
1625 if (mux_client_write_packet(fd, &m) != 0)
1626 fatal("%s: write packet: %s", __func__, strerror(errno));
1627
1628 buffer_clear(&m);
1629
1630 /* Read their reply */
1631 if (mux_client_read_packet(fd, &m) != 0) {
1632 buffer_free(&m);
1633 return 0;
1634 }
1635
1636 type = buffer_get_int(&m);
1637 if (type != MUX_S_ALIVE) {
1638 e = buffer_get_string(&m, NULL);
1639 fatal("%s: master returned error: %s", __func__, e);
1640 }
1641
1642 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1643 fatal("%s: out of sequence reply: my id %u theirs %u",
1644 __func__, muxclient_request_id, rid);
1645 pid = buffer_get_int(&m);
1646 buffer_free(&m);
1647
1648 debug3("%s: done pid = %u", __func__, pid);
1649
1650 muxclient_request_id++;
1651
1652 return pid;
1653 }
1654
1655 static void
mux_client_request_terminate(int fd)1656 mux_client_request_terminate(int fd)
1657 {
1658 Buffer m;
1659 char *e;
1660 u_int type, rid;
1661
1662 debug3("%s: entering", __func__);
1663
1664 buffer_init(&m);
1665 buffer_put_int(&m, MUX_C_TERMINATE);
1666 buffer_put_int(&m, muxclient_request_id);
1667
1668 if (mux_client_write_packet(fd, &m) != 0)
1669 fatal("%s: write packet: %s", __func__, strerror(errno));
1670
1671 buffer_clear(&m);
1672
1673 /* Read their reply */
1674 if (mux_client_read_packet(fd, &m) != 0) {
1675 /* Remote end exited already */
1676 if (errno == EPIPE) {
1677 buffer_free(&m);
1678 return;
1679 }
1680 fatal("%s: read from master failed: %s",
1681 __func__, strerror(errno));
1682 }
1683
1684 type = buffer_get_int(&m);
1685 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1686 fatal("%s: out of sequence reply: my id %u theirs %u",
1687 __func__, muxclient_request_id, rid);
1688 switch (type) {
1689 case MUX_S_OK:
1690 break;
1691 case MUX_S_PERMISSION_DENIED:
1692 e = buffer_get_string(&m, NULL);
1693 fatal("Master refused termination request: %s", e);
1694 case MUX_S_FAILURE:
1695 e = buffer_get_string(&m, NULL);
1696 fatal("%s: termination request failed: %s", __func__, e);
1697 default:
1698 fatal("%s: unexpected response from master 0x%08x",
1699 __func__, type);
1700 }
1701 buffer_free(&m);
1702 muxclient_request_id++;
1703 }
1704
1705 static int
mux_client_forward(int fd,int cancel_flag,u_int ftype,struct Forward * fwd)1706 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd)
1707 {
1708 Buffer m;
1709 char *e, *fwd_desc;
1710 u_int type, rid;
1711
1712 fwd_desc = format_forward(ftype, fwd);
1713 debug("Requesting %s %s",
1714 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc);
1715 free(fwd_desc);
1716
1717 buffer_init(&m);
1718 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD);
1719 buffer_put_int(&m, muxclient_request_id);
1720 buffer_put_int(&m, ftype);
1721 if (fwd->listen_path != NULL) {
1722 buffer_put_cstring(&m, fwd->listen_path);
1723 } else {
1724 buffer_put_cstring(&m,
1725 fwd->listen_host == NULL ? "" :
1726 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host));
1727 }
1728 buffer_put_int(&m, fwd->listen_port);
1729 if (fwd->connect_path != NULL) {
1730 buffer_put_cstring(&m, fwd->connect_path);
1731 } else {
1732 buffer_put_cstring(&m,
1733 fwd->connect_host == NULL ? "" : fwd->connect_host);
1734 }
1735 buffer_put_int(&m, fwd->connect_port);
1736
1737 if (mux_client_write_packet(fd, &m) != 0)
1738 fatal("%s: write packet: %s", __func__, strerror(errno));
1739
1740 buffer_clear(&m);
1741
1742 /* Read their reply */
1743 if (mux_client_read_packet(fd, &m) != 0) {
1744 buffer_free(&m);
1745 return -1;
1746 }
1747
1748 type = buffer_get_int(&m);
1749 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1750 fatal("%s: out of sequence reply: my id %u theirs %u",
1751 __func__, muxclient_request_id, rid);
1752 switch (type) {
1753 case MUX_S_OK:
1754 break;
1755 case MUX_S_REMOTE_PORT:
1756 if (cancel_flag)
1757 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__);
1758 fwd->allocated_port = buffer_get_int(&m);
1759 verbose("Allocated port %u for remote forward to %s:%d",
1760 fwd->allocated_port,
1761 fwd->connect_host ? fwd->connect_host : "",
1762 fwd->connect_port);
1763 if (muxclient_command == SSHMUX_COMMAND_FORWARD)
1764 fprintf(stdout, "%i\n", fwd->allocated_port);
1765 break;
1766 case MUX_S_PERMISSION_DENIED:
1767 e = buffer_get_string(&m, NULL);
1768 buffer_free(&m);
1769 error("Master refused forwarding request: %s", e);
1770 return -1;
1771 case MUX_S_FAILURE:
1772 e = buffer_get_string(&m, NULL);
1773 buffer_free(&m);
1774 error("%s: forwarding request failed: %s", __func__, e);
1775 return -1;
1776 default:
1777 fatal("%s: unexpected response from master 0x%08x",
1778 __func__, type);
1779 }
1780 buffer_free(&m);
1781
1782 muxclient_request_id++;
1783 return 0;
1784 }
1785
1786 static int
mux_client_forwards(int fd,int cancel_flag)1787 mux_client_forwards(int fd, int cancel_flag)
1788 {
1789 int i, ret = 0;
1790
1791 debug3("%s: %s forwardings: %d local, %d remote", __func__,
1792 cancel_flag ? "cancel" : "request",
1793 options.num_local_forwards, options.num_remote_forwards);
1794
1795 /* XXX ExitOnForwardingFailure */
1796 for (i = 0; i < options.num_local_forwards; i++) {
1797 if (mux_client_forward(fd, cancel_flag,
1798 options.local_forwards[i].connect_port == 0 ?
1799 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1800 options.local_forwards + i) != 0)
1801 ret = -1;
1802 }
1803 for (i = 0; i < options.num_remote_forwards; i++) {
1804 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE,
1805 options.remote_forwards + i) != 0)
1806 ret = -1;
1807 }
1808 return ret;
1809 }
1810
1811 static int
mux_client_request_session(int fd)1812 mux_client_request_session(int fd)
1813 {
1814 Buffer m;
1815 char *e, *term;
1816 u_int i, rid, sid, esid, exitval, type, exitval_seen;
1817 extern char **environ;
1818 int devnull, rawmode;
1819
1820 debug3("%s: entering", __func__);
1821
1822 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1823 error("%s: master alive request failed", __func__);
1824 return -1;
1825 }
1826
1827 signal(SIGPIPE, SIG_IGN);
1828
1829 if (stdin_null_flag) {
1830 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1831 fatal("open(/dev/null): %s", strerror(errno));
1832 if (dup2(devnull, STDIN_FILENO) == -1)
1833 fatal("dup2: %s", strerror(errno));
1834 if (devnull > STDERR_FILENO)
1835 close(devnull);
1836 }
1837
1838 term = getenv("TERM");
1839
1840 buffer_init(&m);
1841 buffer_put_int(&m, MUX_C_NEW_SESSION);
1842 buffer_put_int(&m, muxclient_request_id);
1843 buffer_put_cstring(&m, ""); /* reserved */
1844 buffer_put_int(&m, tty_flag);
1845 buffer_put_int(&m, options.forward_x11);
1846 buffer_put_int(&m, options.forward_agent);
1847 buffer_put_int(&m, subsystem_flag);
1848 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ?
1849 0xffffffff : (u_int)options.escape_char);
1850 buffer_put_cstring(&m, term == NULL ? "" : term);
1851 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command));
1852
1853 if (options.num_send_env > 0 && environ != NULL) {
1854 /* Pass environment */
1855 for (i = 0; environ[i] != NULL; i++) {
1856 if (env_permitted(environ[i])) {
1857 buffer_put_cstring(&m, environ[i]);
1858 }
1859 }
1860 }
1861
1862 if (mux_client_write_packet(fd, &m) != 0)
1863 fatal("%s: write packet: %s", __func__, strerror(errno));
1864
1865 /* Send the stdio file descriptors */
1866 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1867 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1868 mm_send_fd(fd, STDERR_FILENO) == -1)
1869 fatal("%s: send fds failed", __func__);
1870
1871 debug3("%s: session request sent", __func__);
1872
1873 /* Read their reply */
1874 buffer_clear(&m);
1875 if (mux_client_read_packet(fd, &m) != 0) {
1876 error("%s: read from master failed: %s",
1877 __func__, strerror(errno));
1878 buffer_free(&m);
1879 return -1;
1880 }
1881
1882 type = buffer_get_int(&m);
1883 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
1884 fatal("%s: out of sequence reply: my id %u theirs %u",
1885 __func__, muxclient_request_id, rid);
1886 switch (type) {
1887 case MUX_S_SESSION_OPENED:
1888 sid = buffer_get_int(&m);
1889 debug("%s: master session id: %u", __func__, sid);
1890 break;
1891 case MUX_S_PERMISSION_DENIED:
1892 e = buffer_get_string(&m, NULL);
1893 buffer_free(&m);
1894 error("Master refused session request: %s", e);
1895 return -1;
1896 case MUX_S_FAILURE:
1897 e = buffer_get_string(&m, NULL);
1898 buffer_free(&m);
1899 error("%s: session request failed: %s", __func__, e);
1900 return -1;
1901 default:
1902 buffer_free(&m);
1903 error("%s: unexpected response from master 0x%08x",
1904 __func__, type);
1905 return -1;
1906 }
1907 muxclient_request_id++;
1908
1909 if (pledge("stdio proc tty", NULL) == -1)
1910 fatal("%s pledge(): %s", __func__, strerror(errno));
1911 platform_pledge_mux();
1912
1913 signal(SIGHUP, control_client_sighandler);
1914 signal(SIGINT, control_client_sighandler);
1915 signal(SIGTERM, control_client_sighandler);
1916 signal(SIGWINCH, control_client_sigrelay);
1917
1918 rawmode = tty_flag;
1919 if (tty_flag)
1920 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1921
1922 /*
1923 * Stick around until the controlee closes the client_fd.
1924 * Before it does, it is expected to write an exit message.
1925 * This process must read the value and wait for the closure of
1926 * the client_fd; if this one closes early, the multiplex master will
1927 * terminate early too (possibly losing data).
1928 */
1929 for (exitval = 255, exitval_seen = 0;;) {
1930 buffer_clear(&m);
1931 if (mux_client_read_packet(fd, &m) != 0)
1932 break;
1933 type = buffer_get_int(&m);
1934 switch (type) {
1935 case MUX_S_TTY_ALLOC_FAIL:
1936 if ((esid = buffer_get_int(&m)) != sid)
1937 fatal("%s: tty alloc fail on unknown session: "
1938 "my id %u theirs %u",
1939 __func__, sid, esid);
1940 leave_raw_mode(options.request_tty ==
1941 REQUEST_TTY_FORCE);
1942 rawmode = 0;
1943 continue;
1944 case MUX_S_EXIT_MESSAGE:
1945 if ((esid = buffer_get_int(&m)) != sid)
1946 fatal("%s: exit on unknown session: "
1947 "my id %u theirs %u",
1948 __func__, sid, esid);
1949 if (exitval_seen)
1950 fatal("%s: exitval sent twice", __func__);
1951 exitval = buffer_get_int(&m);
1952 exitval_seen = 1;
1953 continue;
1954 default:
1955 e = buffer_get_string(&m, NULL);
1956 fatal("%s: master returned error: %s", __func__, e);
1957 }
1958 }
1959
1960 close(fd);
1961 if (rawmode)
1962 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1963
1964 if (muxclient_terminate) {
1965 debug2("Exiting on signal %d", muxclient_terminate);
1966 exitval = 255;
1967 } else if (!exitval_seen) {
1968 debug2("Control master terminated unexpectedly");
1969 exitval = 255;
1970 } else
1971 debug2("Received exit status from master %d", exitval);
1972
1973 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1974 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
1975
1976 exit(exitval);
1977 }
1978
1979 static int
mux_client_proxy(int fd)1980 mux_client_proxy(int fd)
1981 {
1982 Buffer m;
1983 char *e;
1984 u_int type, rid;
1985
1986 buffer_init(&m);
1987 buffer_put_int(&m, MUX_C_PROXY);
1988 buffer_put_int(&m, muxclient_request_id);
1989 if (mux_client_write_packet(fd, &m) != 0)
1990 fatal("%s: write packet: %s", __func__, strerror(errno));
1991
1992 buffer_clear(&m);
1993
1994 /* Read their reply */
1995 if (mux_client_read_packet(fd, &m) != 0) {
1996 buffer_free(&m);
1997 return 0;
1998 }
1999 type = buffer_get_int(&m);
2000 if (type != MUX_S_PROXY) {
2001 e = buffer_get_string(&m, NULL);
2002 fatal("%s: master returned error: %s", __func__, e);
2003 }
2004 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
2005 fatal("%s: out of sequence reply: my id %u theirs %u",
2006 __func__, muxclient_request_id, rid);
2007 buffer_free(&m);
2008
2009 debug3("%s: done", __func__);
2010 muxclient_request_id++;
2011 return 0;
2012 }
2013
2014 static int
mux_client_request_stdio_fwd(int fd)2015 mux_client_request_stdio_fwd(int fd)
2016 {
2017 Buffer m;
2018 char *e;
2019 u_int type, rid, sid;
2020 int devnull;
2021
2022 debug3("%s: entering", __func__);
2023
2024 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
2025 error("%s: master alive request failed", __func__);
2026 return -1;
2027 }
2028
2029 signal(SIGPIPE, SIG_IGN);
2030
2031 if (stdin_null_flag) {
2032 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
2033 fatal("open(/dev/null): %s", strerror(errno));
2034 if (dup2(devnull, STDIN_FILENO) == -1)
2035 fatal("dup2: %s", strerror(errno));
2036 if (devnull > STDERR_FILENO)
2037 close(devnull);
2038 }
2039
2040 buffer_init(&m);
2041 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD);
2042 buffer_put_int(&m, muxclient_request_id);
2043 buffer_put_cstring(&m, ""); /* reserved */
2044 buffer_put_cstring(&m, options.stdio_forward_host);
2045 buffer_put_int(&m, options.stdio_forward_port);
2046
2047 if (mux_client_write_packet(fd, &m) != 0)
2048 fatal("%s: write packet: %s", __func__, strerror(errno));
2049
2050 /* Send the stdio file descriptors */
2051 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
2052 mm_send_fd(fd, STDOUT_FILENO) == -1)
2053 fatal("%s: send fds failed", __func__);
2054
2055 if (pledge("stdio proc tty", NULL) == -1)
2056 fatal("%s pledge(): %s", __func__, strerror(errno));
2057 platform_pledge_mux();
2058
2059 debug3("%s: stdio forward request sent", __func__);
2060
2061 /* Read their reply */
2062 buffer_clear(&m);
2063
2064 if (mux_client_read_packet(fd, &m) != 0) {
2065 error("%s: read from master failed: %s",
2066 __func__, strerror(errno));
2067 buffer_free(&m);
2068 return -1;
2069 }
2070
2071 type = buffer_get_int(&m);
2072 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
2073 fatal("%s: out of sequence reply: my id %u theirs %u",
2074 __func__, muxclient_request_id, rid);
2075 switch (type) {
2076 case MUX_S_SESSION_OPENED:
2077 sid = buffer_get_int(&m);
2078 debug("%s: master session id: %u", __func__, sid);
2079 break;
2080 case MUX_S_PERMISSION_DENIED:
2081 e = buffer_get_string(&m, NULL);
2082 buffer_free(&m);
2083 fatal("Master refused stdio forwarding request: %s", e);
2084 case MUX_S_FAILURE:
2085 e = buffer_get_string(&m, NULL);
2086 buffer_free(&m);
2087 fatal("Stdio forwarding request failed: %s", e);
2088 default:
2089 buffer_free(&m);
2090 error("%s: unexpected response from master 0x%08x",
2091 __func__, type);
2092 return -1;
2093 }
2094 muxclient_request_id++;
2095
2096 signal(SIGHUP, control_client_sighandler);
2097 signal(SIGINT, control_client_sighandler);
2098 signal(SIGTERM, control_client_sighandler);
2099 signal(SIGWINCH, control_client_sigrelay);
2100
2101 /*
2102 * Stick around until the controlee closes the client_fd.
2103 */
2104 buffer_clear(&m);
2105 if (mux_client_read_packet(fd, &m) != 0) {
2106 if (errno == EPIPE ||
2107 (errno == EINTR && muxclient_terminate != 0))
2108 return 0;
2109 fatal("%s: mux_client_read_packet: %s",
2110 __func__, strerror(errno));
2111 }
2112 fatal("%s: master returned unexpected message %u", __func__, type);
2113 }
2114
2115 static void
mux_client_request_stop_listening(int fd)2116 mux_client_request_stop_listening(int fd)
2117 {
2118 Buffer m;
2119 char *e;
2120 u_int type, rid;
2121
2122 debug3("%s: entering", __func__);
2123
2124 buffer_init(&m);
2125 buffer_put_int(&m, MUX_C_STOP_LISTENING);
2126 buffer_put_int(&m, muxclient_request_id);
2127
2128 if (mux_client_write_packet(fd, &m) != 0)
2129 fatal("%s: write packet: %s", __func__, strerror(errno));
2130
2131 buffer_clear(&m);
2132
2133 /* Read their reply */
2134 if (mux_client_read_packet(fd, &m) != 0)
2135 fatal("%s: read from master failed: %s",
2136 __func__, strerror(errno));
2137
2138 type = buffer_get_int(&m);
2139 if ((rid = buffer_get_int(&m)) != muxclient_request_id)
2140 fatal("%s: out of sequence reply: my id %u theirs %u",
2141 __func__, muxclient_request_id, rid);
2142 switch (type) {
2143 case MUX_S_OK:
2144 break;
2145 case MUX_S_PERMISSION_DENIED:
2146 e = buffer_get_string(&m, NULL);
2147 fatal("Master refused stop listening request: %s", e);
2148 case MUX_S_FAILURE:
2149 e = buffer_get_string(&m, NULL);
2150 fatal("%s: stop listening request failed: %s", __func__, e);
2151 default:
2152 fatal("%s: unexpected response from master 0x%08x",
2153 __func__, type);
2154 }
2155 buffer_free(&m);
2156 muxclient_request_id++;
2157 }
2158
2159 /* Multiplex client main loop. */
2160 int
muxclient(const char * path)2161 muxclient(const char *path)
2162 {
2163 struct sockaddr_un addr;
2164 int sock;
2165 u_int pid;
2166
2167 if (muxclient_command == 0) {
2168 if (options.stdio_forward_host != NULL)
2169 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
2170 else
2171 muxclient_command = SSHMUX_COMMAND_OPEN;
2172 }
2173
2174 switch (options.control_master) {
2175 case SSHCTL_MASTER_AUTO:
2176 case SSHCTL_MASTER_AUTO_ASK:
2177 debug("auto-mux: Trying existing master");
2178 /* FALLTHROUGH */
2179 case SSHCTL_MASTER_NO:
2180 break;
2181 default:
2182 return -1;
2183 }
2184
2185 memset(&addr, '\0', sizeof(addr));
2186 addr.sun_family = AF_UNIX;
2187
2188 if (strlcpy(addr.sun_path, path,
2189 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
2190 fatal("ControlPath too long ('%s' >= %u bytes)", path,
2191 (unsigned int)sizeof(addr.sun_path));
2192
2193 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
2194 fatal("%s socket(): %s", __func__, strerror(errno));
2195
2196 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
2197 switch (muxclient_command) {
2198 case SSHMUX_COMMAND_OPEN:
2199 case SSHMUX_COMMAND_STDIO_FWD:
2200 break;
2201 default:
2202 fatal("Control socket connect(%.100s): %s", path,
2203 strerror(errno));
2204 }
2205 if (errno == ECONNREFUSED &&
2206 options.control_master != SSHCTL_MASTER_NO) {
2207 debug("Stale control socket %.100s, unlinking", path);
2208 unlink(path);
2209 } else if (errno == ENOENT) {
2210 debug("Control socket \"%.100s\" does not exist", path);
2211 } else {
2212 error("Control socket connect(%.100s): %s", path,
2213 strerror(errno));
2214 }
2215 close(sock);
2216 return -1;
2217 }
2218 set_nonblock(sock);
2219
2220 if (mux_client_hello_exchange(sock) != 0) {
2221 error("%s: master hello exchange failed", __func__);
2222 close(sock);
2223 return -1;
2224 }
2225
2226 switch (muxclient_command) {
2227 case SSHMUX_COMMAND_ALIVE_CHECK:
2228 if ((pid = mux_client_request_alive(sock)) == 0)
2229 fatal("%s: master alive check failed", __func__);
2230 fprintf(stderr, "Master running (pid=%u)\r\n", pid);
2231 exit(0);
2232 case SSHMUX_COMMAND_TERMINATE:
2233 mux_client_request_terminate(sock);
2234 if (options.log_level != SYSLOG_LEVEL_QUIET)
2235 fprintf(stderr, "Exit request sent.\r\n");
2236 exit(0);
2237 case SSHMUX_COMMAND_FORWARD:
2238 if (mux_client_forwards(sock, 0) != 0)
2239 fatal("%s: master forward request failed", __func__);
2240 exit(0);
2241 case SSHMUX_COMMAND_OPEN:
2242 if (mux_client_forwards(sock, 0) != 0) {
2243 error("%s: master forward request failed", __func__);
2244 return -1;
2245 }
2246 mux_client_request_session(sock);
2247 return -1;
2248 case SSHMUX_COMMAND_STDIO_FWD:
2249 mux_client_request_stdio_fwd(sock);
2250 exit(0);
2251 case SSHMUX_COMMAND_STOP:
2252 mux_client_request_stop_listening(sock);
2253 if (options.log_level != SYSLOG_LEVEL_QUIET)
2254 fprintf(stderr, "Stop listening request sent.\r\n");
2255 exit(0);
2256 case SSHMUX_COMMAND_CANCEL_FWD:
2257 if (mux_client_forwards(sock, 1) != 0)
2258 error("%s: master cancel forward request failed",
2259 __func__);
2260 exit(0);
2261 case SSHMUX_COMMAND_PROXY:
2262 mux_client_proxy(sock);
2263 return (sock);
2264 default:
2265 fatal("unrecognised muxclient_command %d", muxclient_command);
2266 }
2267 }
2268