1 /* $OpenBSD: mux.c,v 1.91 2021/07/23 04:00:59 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 #include "includes.h"
21
22 #include <sys/types.h>
23 #include <sys/stat.h>
24 #include <sys/socket.h>
25 #include <sys/un.h>
26
27 #include <errno.h>
28 #include <fcntl.h>
29 #include <signal.h>
30 #include <stdarg.h>
31 #include <stddef.h>
32 #include <stdlib.h>
33 #include <stdio.h>
34 #include <string.h>
35 #include <unistd.h>
36 #ifdef HAVE_PATHS_H
37 #include <paths.h>
38 #endif
39
40 #ifdef HAVE_POLL_H
41 #include <poll.h>
42 #else
43 # ifdef HAVE_SYS_POLL_H
44 # include <sys/poll.h>
45 # endif
46 #endif
47
48 #ifdef HAVE_UTIL_H
49 # include <util.h>
50 #endif
51
52 #include "openbsd-compat/sys-queue.h"
53 #include "xmalloc.h"
54 #include "log.h"
55 #include "ssh.h"
56 #include "ssh2.h"
57 #include "pathnames.h"
58 #include "misc.h"
59 #include "match.h"
60 #include "sshbuf.h"
61 #include "channels.h"
62 #include "msg.h"
63 #include "packet.h"
64 #include "monitor_fdpass.h"
65 #include "sshpty.h"
66 #include "sshkey.h"
67 #include "readconf.h"
68 #include "clientloop.h"
69 #include "ssherr.h"
70
71 /* from ssh.c */
72 extern int tty_flag;
73 extern Options options;
74 extern char *host;
75 extern struct sshbuf *command;
76 extern volatile sig_atomic_t quit_pending;
77
78 /* Context for session open confirmation callback */
79 struct mux_session_confirm_ctx {
80 u_int want_tty;
81 u_int want_subsys;
82 u_int want_x_fwd;
83 u_int want_agent_fwd;
84 struct sshbuf *cmd;
85 char *term;
86 struct termios tio;
87 char **env;
88 u_int rid;
89 };
90
91 /* Context for stdio fwd open confirmation callback */
92 struct mux_stdio_confirm_ctx {
93 u_int rid;
94 };
95
96 /* Context for global channel callback */
97 struct mux_channel_confirm_ctx {
98 u_int cid; /* channel id */
99 u_int rid; /* request id */
100 int fid; /* forward id */
101 };
102
103 /* fd to control socket */
104 int muxserver_sock = -1;
105
106 /* client request id */
107 u_int muxclient_request_id = 0;
108
109 /* Multiplexing control command */
110 u_int muxclient_command = 0;
111
112 /* Set when signalled. */
113 static volatile sig_atomic_t muxclient_terminate = 0;
114
115 /* PID of multiplex server */
116 static u_int muxserver_pid = 0;
117
118 static Channel *mux_listener_channel = NULL;
119
120 struct mux_master_state {
121 int hello_rcvd;
122 };
123
124 /* mux protocol messages */
125 #define MUX_MSG_HELLO 0x00000001
126 #define MUX_C_NEW_SESSION 0x10000002
127 #define MUX_C_ALIVE_CHECK 0x10000004
128 #define MUX_C_TERMINATE 0x10000005
129 #define MUX_C_OPEN_FWD 0x10000006
130 #define MUX_C_CLOSE_FWD 0x10000007
131 #define MUX_C_NEW_STDIO_FWD 0x10000008
132 #define MUX_C_STOP_LISTENING 0x10000009
133 #define MUX_C_PROXY 0x1000000f
134 #define MUX_S_OK 0x80000001
135 #define MUX_S_PERMISSION_DENIED 0x80000002
136 #define MUX_S_FAILURE 0x80000003
137 #define MUX_S_EXIT_MESSAGE 0x80000004
138 #define MUX_S_ALIVE 0x80000005
139 #define MUX_S_SESSION_OPENED 0x80000006
140 #define MUX_S_REMOTE_PORT 0x80000007
141 #define MUX_S_TTY_ALLOC_FAIL 0x80000008
142 #define MUX_S_PROXY 0x8000000f
143
144 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
145 #define MUX_FWD_LOCAL 1
146 #define MUX_FWD_REMOTE 2
147 #define MUX_FWD_DYNAMIC 3
148
149 static void mux_session_confirm(struct ssh *, int, int, void *);
150 static void mux_stdio_confirm(struct ssh *, int, int, void *);
151
152 static int mux_master_process_hello(struct ssh *, u_int,
153 Channel *, struct sshbuf *, struct sshbuf *);
154 static int mux_master_process_new_session(struct ssh *, u_int,
155 Channel *, struct sshbuf *, struct sshbuf *);
156 static int mux_master_process_alive_check(struct ssh *, u_int,
157 Channel *, struct sshbuf *, struct sshbuf *);
158 static int mux_master_process_terminate(struct ssh *, u_int,
159 Channel *, struct sshbuf *, struct sshbuf *);
160 static int mux_master_process_open_fwd(struct ssh *, u_int,
161 Channel *, struct sshbuf *, struct sshbuf *);
162 static int mux_master_process_close_fwd(struct ssh *, u_int,
163 Channel *, struct sshbuf *, struct sshbuf *);
164 static int mux_master_process_stdio_fwd(struct ssh *, u_int,
165 Channel *, struct sshbuf *, struct sshbuf *);
166 static int mux_master_process_stop_listening(struct ssh *, u_int,
167 Channel *, struct sshbuf *, struct sshbuf *);
168 static int mux_master_process_proxy(struct ssh *, u_int,
169 Channel *, struct sshbuf *, struct sshbuf *);
170
171 static const struct {
172 u_int type;
173 int (*handler)(struct ssh *, u_int, Channel *,
174 struct sshbuf *, struct sshbuf *);
175 } mux_master_handlers[] = {
176 { MUX_MSG_HELLO, mux_master_process_hello },
177 { MUX_C_NEW_SESSION, mux_master_process_new_session },
178 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check },
179 { MUX_C_TERMINATE, mux_master_process_terminate },
180 { MUX_C_OPEN_FWD, mux_master_process_open_fwd },
181 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd },
182 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd },
183 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening },
184 { MUX_C_PROXY, mux_master_process_proxy },
185 { 0, NULL }
186 };
187
188 /* Cleanup callback fired on closure of mux client _session_ channel */
189 /* ARGSUSED */
190 static void
mux_master_session_cleanup_cb(struct ssh * ssh,int cid,void * unused)191 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused)
192 {
193 Channel *cc, *c = channel_by_id(ssh, cid);
194
195 debug3_f("entering for channel %d", cid);
196 if (c == NULL)
197 fatal_f("channel_by_id(%i) == NULL", cid);
198 if (c->ctl_chan != -1) {
199 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
200 fatal_f("channel %d missing control channel %d",
201 c->self, c->ctl_chan);
202 c->ctl_chan = -1;
203 cc->remote_id = 0;
204 cc->have_remote_id = 0;
205 chan_rcvd_oclose(ssh, cc);
206 }
207 channel_cancel_cleanup(ssh, c->self);
208 }
209
210 /* Cleanup callback fired on closure of mux client _control_ channel */
211 /* ARGSUSED */
212 static void
mux_master_control_cleanup_cb(struct ssh * ssh,int cid,void * unused)213 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused)
214 {
215 Channel *sc, *c = channel_by_id(ssh, cid);
216
217 debug3_f("entering for channel %d", cid);
218 if (c == NULL)
219 fatal_f("channel_by_id(%i) == NULL", cid);
220 if (c->have_remote_id) {
221 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL)
222 fatal_f("channel %d missing session channel %u",
223 c->self, c->remote_id);
224 c->remote_id = 0;
225 c->have_remote_id = 0;
226 sc->ctl_chan = -1;
227 if (sc->type != SSH_CHANNEL_OPEN &&
228 sc->type != SSH_CHANNEL_OPENING) {
229 debug2_f("channel %d: not open", sc->self);
230 chan_mark_dead(ssh, sc);
231 } else {
232 if (sc->istate == CHAN_INPUT_OPEN)
233 chan_read_failed(ssh, sc);
234 if (sc->ostate == CHAN_OUTPUT_OPEN)
235 chan_write_failed(ssh, sc);
236 }
237 }
238 channel_cancel_cleanup(ssh, 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_f("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
mux_master_process_hello(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)266 mux_master_process_hello(struct ssh *ssh, u_int rid,
267 Channel *c, struct sshbuf *m, struct sshbuf *reply)
268 {
269 u_int ver;
270 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
271 int r;
272
273 if (state == NULL)
274 fatal_f("channel %d: c->mux_ctx == NULL", c->self);
275 if (state->hello_rcvd) {
276 error_f("HELLO received twice");
277 return -1;
278 }
279 if ((r = sshbuf_get_u32(m, &ver)) != 0) {
280 error_fr(r, "parse");
281 return -1;
282 }
283 if (ver != SSHMUX_VER) {
284 error_f("unsupported multiplexing protocol version %u "
285 "(expected %u)", ver, SSHMUX_VER);
286 return -1;
287 }
288 debug2_f("channel %d client version %u", c->self, ver);
289
290 /* No extensions are presently defined */
291 while (sshbuf_len(m) > 0) {
292 char *name = NULL;
293 size_t value_len = 0;
294
295 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
296 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) {
297 error_fr(r, "parse extension");
298 return -1;
299 }
300 debug2_f("Unrecognised extension \"%s\" length %zu",
301 name, value_len);
302 free(name);
303 }
304 state->hello_rcvd = 1;
305 return 0;
306 }
307
308 /* Enqueue a "ok" response to the reply buffer */
309 static void
reply_ok(struct sshbuf * reply,u_int rid)310 reply_ok(struct sshbuf *reply, u_int rid)
311 {
312 int r;
313
314 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 ||
315 (r = sshbuf_put_u32(reply, rid)) != 0)
316 fatal_fr(r, "reply");
317 }
318
319 /* Enqueue an error response to the reply buffer */
320 static void
reply_error(struct sshbuf * reply,u_int type,u_int rid,const char * msg)321 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg)
322 {
323 int r;
324
325 if ((r = sshbuf_put_u32(reply, type)) != 0 ||
326 (r = sshbuf_put_u32(reply, rid)) != 0 ||
327 (r = sshbuf_put_cstring(reply, msg)) != 0)
328 fatal_fr(r, "reply");
329 }
330
331 static int
mux_master_process_new_session(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)332 mux_master_process_new_session(struct ssh *ssh, u_int rid,
333 Channel *c, struct sshbuf *m, struct sshbuf *reply)
334 {
335 Channel *nc;
336 struct mux_session_confirm_ctx *cctx;
337 char *cmd, *cp;
338 u_int i, j, env_len, escape_char, window, packetmax;
339 int r, new_fd[3];
340
341 /* Reply for SSHMUX_COMMAND_OPEN */
342 cctx = xcalloc(1, sizeof(*cctx));
343 cctx->term = NULL;
344 cctx->rid = rid;
345 cmd = NULL;
346 cctx->env = NULL;
347 env_len = 0;
348 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
349 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 ||
350 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 ||
351 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 ||
352 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 ||
353 (r = sshbuf_get_u32(m, &escape_char)) != 0 ||
354 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 ||
355 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) {
356 malf:
357 free(cmd);
358 for (j = 0; j < env_len; j++)
359 free(cctx->env[j]);
360 free(cctx->env);
361 free(cctx->term);
362 free(cctx);
363 error_f("malformed message");
364 return -1;
365 }
366
367 #define MUX_MAX_ENV_VARS 4096
368 while (sshbuf_len(m) > 0) {
369 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0)
370 goto malf;
371 if (!env_permitted(cp)) {
372 free(cp);
373 continue;
374 }
375 cctx->env = xreallocarray(cctx->env, env_len + 2,
376 sizeof(*cctx->env));
377 cctx->env[env_len++] = cp;
378 cctx->env[env_len] = NULL;
379 if (env_len > MUX_MAX_ENV_VARS) {
380 error_f(">%d environment variables received, "
381 "ignoring additional", MUX_MAX_ENV_VARS);
382 break;
383 }
384 }
385
386 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, "
387 "term \"%s\", cmd \"%s\", env %u", c->self,
388 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
389 cctx->want_subsys, cctx->term, cmd, env_len);
390
391 if ((cctx->cmd = sshbuf_new()) == NULL)
392 fatal_f("sshbuf_new");
393 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0)
394 fatal_fr(r, "sshbuf_put");
395 free(cmd);
396 cmd = NULL;
397
398 /* Gather fds from client */
399 for(i = 0; i < 3; i++) {
400 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
401 error_f("failed to receive fd %d from client", i);
402 for (j = 0; j < i; j++)
403 close(new_fd[j]);
404 for (j = 0; j < env_len; j++)
405 free(cctx->env[j]);
406 free(cctx->env);
407 free(cctx->term);
408 sshbuf_free(cctx->cmd);
409 free(cctx);
410 reply_error(reply, MUX_S_FAILURE, rid,
411 "did not receive file descriptors");
412 return -1;
413 }
414 }
415
416 debug3_f("got fds stdin %d, stdout %d, stderr %d",
417 new_fd[0], new_fd[1], new_fd[2]);
418
419 /* XXX support multiple child sessions in future */
420 if (c->have_remote_id) {
421 debug2_f("session already open");
422 reply_error(reply, MUX_S_FAILURE, rid,
423 "Multiple sessions not supported");
424 cleanup:
425 close(new_fd[0]);
426 close(new_fd[1]);
427 close(new_fd[2]);
428 free(cctx->term);
429 if (env_len != 0) {
430 for (i = 0; i < env_len; i++)
431 free(cctx->env[i]);
432 free(cctx->env);
433 }
434 sshbuf_free(cctx->cmd);
435 free(cctx);
436 return 0;
437 }
438
439 if (options.control_master == SSHCTL_MASTER_ASK ||
440 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
441 if (!ask_permission("Allow shared connection to %s? ", host)) {
442 debug2_f("session refused by user");
443 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
444 "Permission denied");
445 goto cleanup;
446 }
447 }
448
449 /* Try to pick up ttymodes from client before it goes raw */
450 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
451 error_f("tcgetattr: %s", strerror(errno));
452
453 window = CHAN_SES_WINDOW_DEFAULT;
454 packetmax = CHAN_SES_PACKET_DEFAULT;
455 if (cctx->want_tty) {
456 window >>= 1;
457 packetmax >>= 1;
458 }
459
460 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
461 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
462 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO);
463
464 nc->ctl_chan = c->self; /* link session -> control channel */
465 c->remote_id = nc->self; /* link control -> session channel */
466 c->have_remote_id = 1;
467
468 if (cctx->want_tty && escape_char != 0xffffffff) {
469 channel_register_filter(ssh, nc->self,
470 client_simple_escape_filter, NULL,
471 client_filter_cleanup,
472 client_new_escape_filter_ctx((int)escape_char));
473 }
474
475 debug2_f("channel_new: %d linked to control channel %d",
476 nc->self, nc->ctl_chan);
477
478 channel_send_open(ssh, nc->self);
479 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx);
480 c->mux_pause = 1; /* stop handling messages until open_confirm done */
481 channel_register_cleanup(ssh, nc->self,
482 mux_master_session_cleanup_cb, 1);
483
484 /* reply is deferred, sent by mux_session_confirm */
485 return 0;
486 }
487
488 static int
mux_master_process_alive_check(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)489 mux_master_process_alive_check(struct ssh *ssh, u_int rid,
490 Channel *c, struct sshbuf *m, struct sshbuf *reply)
491 {
492 int r;
493
494 debug2_f("channel %d: alive check", c->self);
495
496 /* prepare reply */
497 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 ||
498 (r = sshbuf_put_u32(reply, rid)) != 0 ||
499 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0)
500 fatal_fr(r, "reply");
501
502 return 0;
503 }
504
505 static int
mux_master_process_terminate(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)506 mux_master_process_terminate(struct ssh *ssh, u_int rid,
507 Channel *c, struct sshbuf *m, struct sshbuf *reply)
508 {
509 debug2_f("channel %d: terminate request", c->self);
510
511 if (options.control_master == SSHCTL_MASTER_ASK ||
512 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
513 if (!ask_permission("Terminate shared connection to %s? ",
514 host)) {
515 debug2_f("termination refused by user");
516 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
517 "Permission denied");
518 return 0;
519 }
520 }
521
522 quit_pending = 1;
523 reply_ok(reply, rid);
524 /* XXX exit happens too soon - message never makes it to client */
525 return 0;
526 }
527
528 static char *
format_forward(u_int ftype,struct Forward * fwd)529 format_forward(u_int ftype, struct Forward *fwd)
530 {
531 char *ret;
532
533 switch (ftype) {
534 case MUX_FWD_LOCAL:
535 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
536 (fwd->listen_path != NULL) ? fwd->listen_path :
537 (fwd->listen_host == NULL) ?
538 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
539 fwd->listen_host, fwd->listen_port,
540 (fwd->connect_path != NULL) ? fwd->connect_path :
541 fwd->connect_host, fwd->connect_port);
542 break;
543 case MUX_FWD_DYNAMIC:
544 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
545 (fwd->listen_host == NULL) ?
546 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
547 fwd->listen_host, fwd->listen_port);
548 break;
549 case MUX_FWD_REMOTE:
550 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
551 (fwd->listen_path != NULL) ? fwd->listen_path :
552 (fwd->listen_host == NULL) ?
553 "LOCALHOST" : fwd->listen_host,
554 fwd->listen_port,
555 (fwd->connect_path != NULL) ? fwd->connect_path :
556 fwd->connect_host, fwd->connect_port);
557 break;
558 default:
559 fatal_f("unknown forward type %u", ftype);
560 }
561 return ret;
562 }
563
564 static int
compare_host(const char * a,const char * b)565 compare_host(const char *a, const char *b)
566 {
567 if (a == NULL && b == NULL)
568 return 1;
569 if (a == NULL || b == NULL)
570 return 0;
571 return strcmp(a, b) == 0;
572 }
573
574 static int
compare_forward(struct Forward * a,struct Forward * b)575 compare_forward(struct Forward *a, struct Forward *b)
576 {
577 if (!compare_host(a->listen_host, b->listen_host))
578 return 0;
579 if (!compare_host(a->listen_path, b->listen_path))
580 return 0;
581 if (a->listen_port != b->listen_port)
582 return 0;
583 if (!compare_host(a->connect_host, b->connect_host))
584 return 0;
585 if (!compare_host(a->connect_path, b->connect_path))
586 return 0;
587 if (a->connect_port != b->connect_port)
588 return 0;
589
590 return 1;
591 }
592
593 static void
mux_confirm_remote_forward(struct ssh * ssh,int type,u_int32_t seq,void * ctxt)594 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
595 {
596 struct mux_channel_confirm_ctx *fctx = ctxt;
597 char *failmsg = NULL;
598 struct Forward *rfwd;
599 Channel *c;
600 struct sshbuf *out;
601 u_int port;
602 int r;
603
604 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) {
605 /* no channel for reply */
606 error_f("unknown channel");
607 return;
608 }
609 if ((out = sshbuf_new()) == NULL)
610 fatal_f("sshbuf_new");
611 if (fctx->fid >= options.num_remote_forwards ||
612 (options.remote_forwards[fctx->fid].connect_path == NULL &&
613 options.remote_forwards[fctx->fid].connect_host == NULL)) {
614 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
615 goto fail;
616 }
617 rfwd = &options.remote_forwards[fctx->fid];
618 debug_f("%s for: listen %d, connect %s:%d",
619 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
620 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
621 rfwd->connect_host, rfwd->connect_port);
622 if (type == SSH2_MSG_REQUEST_SUCCESS) {
623 if (rfwd->listen_port == 0) {
624 if ((r = sshpkt_get_u32(ssh, &port)) != 0)
625 fatal_fr(r, "parse port");
626 if (port > 65535) {
627 fatal("Invalid allocated port %u for "
628 "mux remote forward to %s:%d", port,
629 rfwd->connect_host, rfwd->connect_port);
630 }
631 rfwd->allocated_port = (int)port;
632 debug("Allocated port %u for mux remote forward"
633 " to %s:%d", rfwd->allocated_port,
634 rfwd->connect_host, rfwd->connect_port);
635 if ((r = sshbuf_put_u32(out,
636 MUX_S_REMOTE_PORT)) != 0 ||
637 (r = sshbuf_put_u32(out, fctx->rid)) != 0 ||
638 (r = sshbuf_put_u32(out,
639 rfwd->allocated_port)) != 0)
640 fatal_fr(r, "reply");
641 channel_update_permission(ssh, rfwd->handle,
642 rfwd->allocated_port);
643 } else {
644 reply_ok(out, fctx->rid);
645 }
646 goto out;
647 } else {
648 if (rfwd->listen_port == 0)
649 channel_update_permission(ssh, rfwd->handle, -1);
650 if (rfwd->listen_path != NULL)
651 xasprintf(&failmsg, "remote port forwarding failed for "
652 "listen path %s", rfwd->listen_path);
653 else
654 xasprintf(&failmsg, "remote port forwarding failed for "
655 "listen port %d", rfwd->listen_port);
656
657 debug2_f("clearing registered forwarding for listen %d, "
658 "connect %s:%d", rfwd->listen_port,
659 rfwd->connect_path ? rfwd->connect_path :
660 rfwd->connect_host, rfwd->connect_port);
661
662 free(rfwd->listen_host);
663 free(rfwd->listen_path);
664 free(rfwd->connect_host);
665 free(rfwd->connect_path);
666 memset(rfwd, 0, sizeof(*rfwd));
667 }
668 fail:
669 error_f("%s", failmsg);
670 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg);
671 free(failmsg);
672 out:
673 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
674 fatal_fr(r, "enqueue");
675 sshbuf_free(out);
676 if (c->mux_pause <= 0)
677 fatal_f("mux_pause %d", c->mux_pause);
678 c->mux_pause = 0; /* start processing messages again */
679 }
680
681 static int
mux_master_process_open_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)682 mux_master_process_open_fwd(struct ssh *ssh, u_int rid,
683 Channel *c, struct sshbuf *m, struct sshbuf *reply)
684 {
685 struct Forward fwd;
686 char *fwd_desc = NULL;
687 char *listen_addr, *connect_addr;
688 u_int ftype;
689 u_int lport, cport;
690 int r, i, ret = 0, freefwd = 1;
691
692 memset(&fwd, 0, sizeof(fwd));
693
694 /* XXX - lport/cport check redundant */
695 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
696 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
697 (r = sshbuf_get_u32(m, &lport)) != 0 ||
698 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
699 (r = sshbuf_get_u32(m, &cport)) != 0 ||
700 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
701 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
702 error_f("malformed message");
703 ret = -1;
704 goto out;
705 }
706 if (*listen_addr == '\0') {
707 free(listen_addr);
708 listen_addr = NULL;
709 }
710 if (*connect_addr == '\0') {
711 free(connect_addr);
712 connect_addr = NULL;
713 }
714
715 memset(&fwd, 0, sizeof(fwd));
716 fwd.listen_port = lport;
717 if (fwd.listen_port == PORT_STREAMLOCAL)
718 fwd.listen_path = listen_addr;
719 else
720 fwd.listen_host = listen_addr;
721 fwd.connect_port = cport;
722 if (fwd.connect_port == PORT_STREAMLOCAL)
723 fwd.connect_path = connect_addr;
724 else
725 fwd.connect_host = connect_addr;
726
727 debug2_f("channel %d: request %s", c->self,
728 (fwd_desc = format_forward(ftype, &fwd)));
729
730 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
731 ftype != MUX_FWD_DYNAMIC) {
732 logit_f("invalid forwarding type %u", ftype);
733 invalid:
734 free(listen_addr);
735 free(connect_addr);
736 reply_error(reply, MUX_S_FAILURE, rid,
737 "Invalid forwarding request");
738 return 0;
739 }
740 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) {
741 logit_f("streamlocal and dynamic forwards "
742 "are mutually exclusive");
743 goto invalid;
744 }
745 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) {
746 logit_f("invalid listen port %u", fwd.listen_port);
747 goto invalid;
748 }
749 if ((fwd.connect_port != PORT_STREAMLOCAL &&
750 fwd.connect_port >= 65536) ||
751 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE &&
752 fwd.connect_port == 0)) {
753 logit_f("invalid connect port %u",
754 fwd.connect_port);
755 goto invalid;
756 }
757 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL &&
758 fwd.connect_path == NULL) {
759 logit_f("missing connect host");
760 goto invalid;
761 }
762
763 /* Skip forwards that have already been requested */
764 switch (ftype) {
765 case MUX_FWD_LOCAL:
766 case MUX_FWD_DYNAMIC:
767 for (i = 0; i < options.num_local_forwards; i++) {
768 if (compare_forward(&fwd,
769 options.local_forwards + i)) {
770 exists:
771 debug2_f("found existing forwarding");
772 reply_ok(reply, rid);
773 goto out;
774 }
775 }
776 break;
777 case MUX_FWD_REMOTE:
778 for (i = 0; i < options.num_remote_forwards; i++) {
779 if (!compare_forward(&fwd, options.remote_forwards + i))
780 continue;
781 if (fwd.listen_port != 0)
782 goto exists;
783 debug2_f("found allocated port");
784 if ((r = sshbuf_put_u32(reply,
785 MUX_S_REMOTE_PORT)) != 0 ||
786 (r = sshbuf_put_u32(reply, rid)) != 0 ||
787 (r = sshbuf_put_u32(reply,
788 options.remote_forwards[i].allocated_port)) != 0)
789 fatal_fr(r, "reply FWD_REMOTE");
790 goto out;
791 }
792 break;
793 }
794
795 if (options.control_master == SSHCTL_MASTER_ASK ||
796 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
797 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
798 debug2_f("forwarding refused by user");
799 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
800 "Permission denied");
801 goto out;
802 }
803 }
804
805 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
806 if (!channel_setup_local_fwd_listener(ssh, &fwd,
807 &options.fwd_opts)) {
808 fail:
809 logit_f("requested %s failed", fwd_desc);
810 reply_error(reply, MUX_S_FAILURE, rid,
811 "Port forwarding failed");
812 goto out;
813 }
814 add_local_forward(&options, &fwd);
815 freefwd = 0;
816 } else {
817 struct mux_channel_confirm_ctx *fctx;
818
819 fwd.handle = channel_request_remote_forwarding(ssh, &fwd);
820 if (fwd.handle < 0)
821 goto fail;
822 add_remote_forward(&options, &fwd);
823 fctx = xcalloc(1, sizeof(*fctx));
824 fctx->cid = c->self;
825 fctx->rid = rid;
826 fctx->fid = options.num_remote_forwards - 1;
827 client_register_global_confirm(mux_confirm_remote_forward,
828 fctx);
829 freefwd = 0;
830 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
831 /* delayed reply in mux_confirm_remote_forward */
832 goto out;
833 }
834 reply_ok(reply, rid);
835 out:
836 free(fwd_desc);
837 if (freefwd) {
838 free(fwd.listen_host);
839 free(fwd.listen_path);
840 free(fwd.connect_host);
841 free(fwd.connect_path);
842 }
843 return ret;
844 }
845
846 static int
mux_master_process_close_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)847 mux_master_process_close_fwd(struct ssh *ssh, u_int rid,
848 Channel *c, struct sshbuf *m, struct sshbuf *reply)
849 {
850 struct Forward fwd, *found_fwd;
851 char *fwd_desc = NULL;
852 const char *error_reason = NULL;
853 char *listen_addr = NULL, *connect_addr = NULL;
854 u_int ftype;
855 int r, i, ret = 0;
856 u_int lport, cport;
857
858 memset(&fwd, 0, sizeof(fwd));
859
860 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
861 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
862 (r = sshbuf_get_u32(m, &lport)) != 0 ||
863 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
864 (r = sshbuf_get_u32(m, &cport)) != 0 ||
865 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
866 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
867 error_f("malformed message");
868 ret = -1;
869 goto out;
870 }
871
872 if (*listen_addr == '\0') {
873 free(listen_addr);
874 listen_addr = NULL;
875 }
876 if (*connect_addr == '\0') {
877 free(connect_addr);
878 connect_addr = NULL;
879 }
880
881 memset(&fwd, 0, sizeof(fwd));
882 fwd.listen_port = lport;
883 if (fwd.listen_port == PORT_STREAMLOCAL)
884 fwd.listen_path = listen_addr;
885 else
886 fwd.listen_host = listen_addr;
887 fwd.connect_port = cport;
888 if (fwd.connect_port == PORT_STREAMLOCAL)
889 fwd.connect_path = connect_addr;
890 else
891 fwd.connect_host = connect_addr;
892
893 debug2_f("channel %d: request cancel %s", c->self,
894 (fwd_desc = format_forward(ftype, &fwd)));
895
896 /* make sure this has been requested */
897 found_fwd = NULL;
898 switch (ftype) {
899 case MUX_FWD_LOCAL:
900 case MUX_FWD_DYNAMIC:
901 for (i = 0; i < options.num_local_forwards; i++) {
902 if (compare_forward(&fwd,
903 options.local_forwards + i)) {
904 found_fwd = options.local_forwards + i;
905 break;
906 }
907 }
908 break;
909 case MUX_FWD_REMOTE:
910 for (i = 0; i < options.num_remote_forwards; i++) {
911 if (compare_forward(&fwd,
912 options.remote_forwards + i)) {
913 found_fwd = options.remote_forwards + i;
914 break;
915 }
916 }
917 break;
918 }
919
920 if (found_fwd == NULL)
921 error_reason = "port not forwarded";
922 else if (ftype == MUX_FWD_REMOTE) {
923 /*
924 * This shouldn't fail unless we confused the host/port
925 * between options.remote_forwards and permitted_opens.
926 * However, for dynamic allocated listen ports we need
927 * to use the actual listen port.
928 */
929 if (channel_request_rforward_cancel(ssh, found_fwd) == -1)
930 error_reason = "port not in permitted opens";
931 } else { /* local and dynamic forwards */
932 /* Ditto */
933 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port,
934 &options.fwd_opts) == -1)
935 error_reason = "port not found";
936 }
937
938 if (error_reason != NULL)
939 reply_error(reply, MUX_S_FAILURE, rid, error_reason);
940 else {
941 reply_ok(reply, rid);
942 free(found_fwd->listen_host);
943 free(found_fwd->listen_path);
944 free(found_fwd->connect_host);
945 free(found_fwd->connect_path);
946 found_fwd->listen_host = found_fwd->connect_host = NULL;
947 found_fwd->listen_path = found_fwd->connect_path = NULL;
948 found_fwd->listen_port = found_fwd->connect_port = 0;
949 }
950 out:
951 free(fwd_desc);
952 free(listen_addr);
953 free(connect_addr);
954
955 return ret;
956 }
957
958 static int
mux_master_process_stdio_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)959 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid,
960 Channel *c, struct sshbuf *m, struct sshbuf *reply)
961 {
962 Channel *nc;
963 char *chost = NULL;
964 u_int cport, i, j;
965 int r, new_fd[2];
966 struct mux_stdio_confirm_ctx *cctx;
967
968 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
969 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
970 (r = sshbuf_get_u32(m, &cport)) != 0) {
971 free(chost);
972 error_f("malformed message");
973 return -1;
974 }
975
976 debug2_f("channel %d: stdio fwd to %s:%u", c->self, chost, cport);
977
978 /* Gather fds from client */
979 for(i = 0; i < 2; i++) {
980 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
981 error_f("failed to receive fd %d from client", i);
982 for (j = 0; j < i; j++)
983 close(new_fd[j]);
984 free(chost);
985
986 /* prepare reply */
987 reply_error(reply, MUX_S_FAILURE, rid,
988 "did not receive file descriptors");
989 return -1;
990 }
991 }
992
993 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]);
994
995 /* XXX support multiple child sessions in future */
996 if (c->have_remote_id) {
997 debug2_f("session already open");
998 reply_error(reply, MUX_S_FAILURE, rid,
999 "Multiple sessions not supported");
1000 cleanup:
1001 close(new_fd[0]);
1002 close(new_fd[1]);
1003 free(chost);
1004 return 0;
1005 }
1006
1007 if (options.control_master == SSHCTL_MASTER_ASK ||
1008 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1009 if (!ask_permission("Allow forward to %s:%u? ",
1010 chost, cport)) {
1011 debug2_f("stdio fwd refused by user");
1012 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1013 "Permission denied");
1014 goto cleanup;
1015 }
1016 }
1017
1018 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1],
1019 CHANNEL_NONBLOCK_STDIO);
1020 free(chost);
1021
1022 nc->ctl_chan = c->self; /* link session -> control channel */
1023 c->remote_id = nc->self; /* link control -> session channel */
1024 c->have_remote_id = 1;
1025
1026 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan);
1027
1028 channel_register_cleanup(ssh, nc->self,
1029 mux_master_session_cleanup_cb, 1);
1030
1031 cctx = xcalloc(1, sizeof(*cctx));
1032 cctx->rid = rid;
1033 channel_register_open_confirm(ssh, 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(struct ssh * ssh,int id,int success,void * arg)1042 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1043 {
1044 struct mux_stdio_confirm_ctx *cctx = arg;
1045 Channel *c, *cc;
1046 struct sshbuf *reply;
1047 int r;
1048
1049 if (cctx == NULL)
1050 fatal_f("cctx == NULL");
1051 if ((c = channel_by_id(ssh, id)) == NULL)
1052 fatal_f("no channel for id %d", id);
1053 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1054 fatal_f("channel %d lacks control channel %d",
1055 id, c->ctl_chan);
1056 if ((reply = sshbuf_new()) == NULL)
1057 fatal_f("sshbuf_new");
1058
1059 if (!success) {
1060 debug3_f("sending failure reply");
1061 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1062 "Session open refused by peer");
1063 /* prepare reply */
1064 goto done;
1065 }
1066
1067 debug3_f("sending success reply");
1068 /* prepare reply */
1069 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1070 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1071 (r = sshbuf_put_u32(reply, c->self)) != 0)
1072 fatal_fr(r, "reply");
1073
1074 done:
1075 /* Send reply */
1076 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1077 fatal_fr(r, "enqueue");
1078 sshbuf_free(reply);
1079
1080 if (cc->mux_pause <= 0)
1081 fatal_f("mux_pause %d", cc->mux_pause);
1082 cc->mux_pause = 0; /* start processing messages again */
1083 c->open_confirm_ctx = NULL;
1084 free(cctx);
1085 }
1086
1087 static int
mux_master_process_stop_listening(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1088 mux_master_process_stop_listening(struct ssh *ssh, u_int rid,
1089 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1090 {
1091 debug_f("channel %d: stop listening", c->self);
1092
1093 if (options.control_master == SSHCTL_MASTER_ASK ||
1094 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1095 if (!ask_permission("Disable further multiplexing on shared "
1096 "connection to %s? ", host)) {
1097 debug2_f("stop listen refused by user");
1098 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1099 "Permission denied");
1100 return 0;
1101 }
1102 }
1103
1104 if (mux_listener_channel != NULL) {
1105 channel_free(ssh, mux_listener_channel);
1106 client_stop_mux();
1107 free(options.control_path);
1108 options.control_path = NULL;
1109 mux_listener_channel = NULL;
1110 muxserver_sock = -1;
1111 }
1112
1113 reply_ok(reply, rid);
1114 return 0;
1115 }
1116
1117 static int
mux_master_process_proxy(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1118 mux_master_process_proxy(struct ssh *ssh, u_int rid,
1119 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1120 {
1121 int r;
1122
1123 debug_f("channel %d: proxy request", c->self);
1124
1125 c->mux_rcb = channel_proxy_downstream;
1126 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 ||
1127 (r = sshbuf_put_u32(reply, rid)) != 0)
1128 fatal_fr(r, "reply");
1129
1130 return 0;
1131 }
1132
1133 /* Channel callbacks fired on read/write from mux client fd */
1134 static int
mux_master_read_cb(struct ssh * ssh,Channel * c)1135 mux_master_read_cb(struct ssh *ssh, Channel *c)
1136 {
1137 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
1138 struct sshbuf *in = NULL, *out = NULL;
1139 u_int type, rid, i;
1140 int r, ret = -1;
1141
1142 if ((out = sshbuf_new()) == NULL)
1143 fatal_f("sshbuf_new");
1144
1145 /* Setup ctx and */
1146 if (c->mux_ctx == NULL) {
1147 state = xcalloc(1, sizeof(*state));
1148 c->mux_ctx = state;
1149 channel_register_cleanup(ssh, c->self,
1150 mux_master_control_cleanup_cb, 0);
1151
1152 /* Send hello */
1153 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 ||
1154 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0)
1155 fatal_fr(r, "reply");
1156 /* no extensions */
1157 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
1158 fatal_fr(r, "enqueue");
1159 debug3_f("channel %d: hello sent", c->self);
1160 ret = 0;
1161 goto out;
1162 }
1163
1164 /* Channel code ensures that we receive whole packets */
1165 if ((r = sshbuf_froms(c->input, &in)) != 0) {
1166 malf:
1167 error_f("malformed message");
1168 goto out;
1169 }
1170
1171 if ((r = sshbuf_get_u32(in, &type)) != 0)
1172 goto malf;
1173 debug3_f("channel %d packet type 0x%08x len %zu", c->self,
1174 type, sshbuf_len(in));
1175
1176 if (type == MUX_MSG_HELLO)
1177 rid = 0;
1178 else {
1179 if (!state->hello_rcvd) {
1180 error_f("expected MUX_MSG_HELLO(0x%08x), "
1181 "received 0x%08x", MUX_MSG_HELLO, type);
1182 goto out;
1183 }
1184 if ((r = sshbuf_get_u32(in, &rid)) != 0)
1185 goto malf;
1186 }
1187
1188 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
1189 if (type == mux_master_handlers[i].type) {
1190 ret = mux_master_handlers[i].handler(ssh, rid,
1191 c, in, out);
1192 break;
1193 }
1194 }
1195 if (mux_master_handlers[i].handler == NULL) {
1196 error_f("unsupported mux message 0x%08x", type);
1197 reply_error(out, MUX_S_FAILURE, rid, "unsupported request");
1198 ret = 0;
1199 }
1200 /* Enqueue reply packet */
1201 if (sshbuf_len(out) != 0 &&
1202 (r = sshbuf_put_stringb(c->output, out)) != 0)
1203 fatal_fr(r, "enqueue");
1204 out:
1205 sshbuf_free(in);
1206 sshbuf_free(out);
1207 return ret;
1208 }
1209
1210 void
mux_exit_message(struct ssh * ssh,Channel * c,int exitval)1211 mux_exit_message(struct ssh *ssh, Channel *c, int exitval)
1212 {
1213 struct sshbuf *m;
1214 Channel *mux_chan;
1215 int r;
1216
1217 debug3_f("channel %d: exit message, exitval %d", c->self, exitval);
1218
1219 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1220 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan);
1221
1222 /* Append exit message packet to control socket output queue */
1223 if ((m = sshbuf_new()) == NULL)
1224 fatal_f("sshbuf_new");
1225 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 ||
1226 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1227 (r = sshbuf_put_u32(m, exitval)) != 0 ||
1228 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1229 fatal_fr(r, "reply");
1230 sshbuf_free(m);
1231 }
1232
1233 void
mux_tty_alloc_failed(struct ssh * ssh,Channel * c)1234 mux_tty_alloc_failed(struct ssh *ssh, Channel *c)
1235 {
1236 struct sshbuf *m;
1237 Channel *mux_chan;
1238 int r;
1239
1240 debug3_f("channel %d: TTY alloc failed", c->self);
1241
1242 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1243 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan);
1244
1245 /* Append exit message packet to control socket output queue */
1246 if ((m = sshbuf_new()) == NULL)
1247 fatal_f("sshbuf_new");
1248 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 ||
1249 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1250 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1251 fatal_fr(r, "reply");
1252 sshbuf_free(m);
1253 }
1254
1255 /* Prepare a mux master to listen on a Unix domain socket. */
1256 void
muxserver_listen(struct ssh * ssh)1257 muxserver_listen(struct ssh *ssh)
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_f("temporary control path %s", 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_f("link mux listener %s => %s: %s",
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(ssh, "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_f("mux listener channel %d fd %d",
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(struct ssh * ssh,int id,int success,void * arg)1341 mux_session_confirm(struct ssh *ssh, 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, r;
1347 struct sshbuf *reply;
1348
1349 if (cctx == NULL)
1350 fatal_f("cctx == NULL");
1351 if ((c = channel_by_id(ssh, id)) == NULL)
1352 fatal_f("no channel for id %d", id);
1353 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1354 fatal_f("channel %d lacks control channel %d",
1355 id, c->ctl_chan);
1356 if ((reply = sshbuf_new()) == NULL)
1357 fatal_f("sshbuf_new");
1358
1359 if (!success) {
1360 debug3_f("sending failure reply");
1361 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1362 "Session open refused by peer");
1363 goto done;
1364 }
1365
1366 display = getenv("DISPLAY");
1367 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1368 char *proto, *data;
1369
1370 /* Get reasonable local authentication information. */
1371 if (client_x11_get_proto(ssh, display, options.xauth_location,
1372 options.forward_x11_trusted, options.forward_x11_timeout,
1373 &proto, &data) == 0) {
1374 /* Request forwarding with authentication spoofing. */
1375 debug("Requesting X11 forwarding with authentication "
1376 "spoofing.");
1377 x11_request_forwarding_with_spoofing(ssh, id,
1378 display, proto, data, 1);
1379 /* XXX exit_on_forward_failure */
1380 client_expect_confirm(ssh, id, "X11 forwarding",
1381 CONFIRM_WARN);
1382 }
1383 }
1384
1385 if (cctx->want_agent_fwd && options.forward_agent) {
1386 debug("Requesting authentication agent forwarding.");
1387 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
1388 if ((r = sshpkt_send(ssh)) != 0)
1389 fatal_fr(r, "send");
1390 }
1391
1392 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys,
1393 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env);
1394
1395 debug3_f("sending success reply");
1396 /* prepare reply */
1397 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1398 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1399 (r = sshbuf_put_u32(reply, c->self)) != 0)
1400 fatal_fr(r, "reply");
1401
1402 done:
1403 /* Send reply */
1404 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1405 fatal_fr(r, "enqueue");
1406 sshbuf_free(reply);
1407
1408 if (cc->mux_pause <= 0)
1409 fatal_f("mux_pause %d", cc->mux_pause);
1410 cc->mux_pause = 0; /* start processing messages again */
1411 c->open_confirm_ctx = NULL;
1412 sshbuf_free(cctx->cmd);
1413 free(cctx->term);
1414 if (cctx->env != NULL) {
1415 for (i = 0; cctx->env[i] != NULL; i++)
1416 free(cctx->env[i]);
1417 free(cctx->env);
1418 }
1419 free(cctx);
1420 }
1421
1422 /* ** Multiplexing client support */
1423
1424 /* Exit signal handler */
1425 static void
control_client_sighandler(int signo)1426 control_client_sighandler(int signo)
1427 {
1428 muxclient_terminate = signo;
1429 }
1430
1431 /*
1432 * Relay signal handler - used to pass some signals from mux client to
1433 * mux master.
1434 */
1435 static void
control_client_sigrelay(int signo)1436 control_client_sigrelay(int signo)
1437 {
1438 int save_errno = errno;
1439
1440 if (muxserver_pid > 1)
1441 kill(muxserver_pid, signo);
1442
1443 errno = save_errno;
1444 }
1445
1446 static int
mux_client_read(int fd,struct sshbuf * b,size_t need)1447 mux_client_read(int fd, struct sshbuf *b, size_t need)
1448 {
1449 size_t have;
1450 ssize_t len;
1451 u_char *p;
1452 struct pollfd pfd;
1453 int r;
1454
1455 pfd.fd = fd;
1456 pfd.events = POLLIN;
1457 if ((r = sshbuf_reserve(b, need, &p)) != 0)
1458 fatal_fr(r, "reserve");
1459 for (have = 0; have < need; ) {
1460 if (muxclient_terminate) {
1461 errno = EINTR;
1462 return -1;
1463 }
1464 len = read(fd, p + have, need - have);
1465 if (len == -1) {
1466 switch (errno) {
1467 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1468 case EWOULDBLOCK:
1469 #endif
1470 case EAGAIN:
1471 (void)poll(&pfd, 1, -1);
1472 /* FALLTHROUGH */
1473 case EINTR:
1474 continue;
1475 default:
1476 return -1;
1477 }
1478 }
1479 if (len == 0) {
1480 errno = EPIPE;
1481 return -1;
1482 }
1483 have += (size_t)len;
1484 }
1485 return 0;
1486 }
1487
1488 static int
mux_client_write_packet(int fd,struct sshbuf * m)1489 mux_client_write_packet(int fd, struct sshbuf *m)
1490 {
1491 struct sshbuf *queue;
1492 u_int have, need;
1493 int r, oerrno, len;
1494 const u_char *ptr;
1495 struct pollfd pfd;
1496
1497 pfd.fd = fd;
1498 pfd.events = POLLOUT;
1499 if ((queue = sshbuf_new()) == NULL)
1500 fatal_f("sshbuf_new");
1501 if ((r = sshbuf_put_stringb(queue, m)) != 0)
1502 fatal_fr(r, "enqueue");
1503
1504 need = sshbuf_len(queue);
1505 ptr = sshbuf_ptr(queue);
1506
1507 for (have = 0; have < need; ) {
1508 if (muxclient_terminate) {
1509 sshbuf_free(queue);
1510 errno = EINTR;
1511 return -1;
1512 }
1513 len = write(fd, ptr + have, need - have);
1514 if (len == -1) {
1515 switch (errno) {
1516 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1517 case EWOULDBLOCK:
1518 #endif
1519 case EAGAIN:
1520 (void)poll(&pfd, 1, -1);
1521 /* FALLTHROUGH */
1522 case EINTR:
1523 continue;
1524 default:
1525 oerrno = errno;
1526 sshbuf_free(queue);
1527 errno = oerrno;
1528 return -1;
1529 }
1530 }
1531 if (len == 0) {
1532 sshbuf_free(queue);
1533 errno = EPIPE;
1534 return -1;
1535 }
1536 have += (u_int)len;
1537 }
1538 sshbuf_free(queue);
1539 return 0;
1540 }
1541
1542 static int
mux_client_read_packet(int fd,struct sshbuf * m)1543 mux_client_read_packet(int fd, struct sshbuf *m)
1544 {
1545 struct sshbuf *queue;
1546 size_t need, have;
1547 const u_char *ptr;
1548 int r, oerrno;
1549
1550 if ((queue = sshbuf_new()) == NULL)
1551 fatal_f("sshbuf_new");
1552 if (mux_client_read(fd, queue, 4) != 0) {
1553 if ((oerrno = errno) == EPIPE)
1554 debug3_f("read header failed: %s",
1555 strerror(errno));
1556 sshbuf_free(queue);
1557 errno = oerrno;
1558 return -1;
1559 }
1560 need = PEEK_U32(sshbuf_ptr(queue));
1561 if (mux_client_read(fd, queue, need) != 0) {
1562 oerrno = errno;
1563 debug3_f("read body failed: %s", strerror(errno));
1564 sshbuf_free(queue);
1565 errno = oerrno;
1566 return -1;
1567 }
1568 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 ||
1569 (r = sshbuf_put(m, ptr, have)) != 0)
1570 fatal_fr(r, "dequeue");
1571 sshbuf_free(queue);
1572 return 0;
1573 }
1574
1575 static int
mux_client_hello_exchange(int fd)1576 mux_client_hello_exchange(int fd)
1577 {
1578 struct sshbuf *m;
1579 u_int type, ver;
1580 int r, ret = -1;
1581
1582 if ((m = sshbuf_new()) == NULL)
1583 fatal_f("sshbuf_new");
1584 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 ||
1585 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0)
1586 fatal_fr(r, "assemble hello");
1587 /* no extensions */
1588
1589 if (mux_client_write_packet(fd, m) != 0) {
1590 debug_f("write packet: %s", strerror(errno));
1591 goto out;
1592 }
1593
1594 sshbuf_reset(m);
1595
1596 /* Read their HELLO */
1597 if (mux_client_read_packet(fd, m) != 0) {
1598 debug_f("read packet failed");
1599 goto out;
1600 }
1601
1602 if ((r = sshbuf_get_u32(m, &type)) != 0)
1603 fatal_fr(r, "parse type");
1604 if (type != MUX_MSG_HELLO) {
1605 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type);
1606 goto out;
1607 }
1608 if ((r = sshbuf_get_u32(m, &ver)) != 0)
1609 fatal_fr(r, "parse version");
1610 if (ver != SSHMUX_VER) {
1611 error("Unsupported multiplexing protocol version %d "
1612 "(expected %d)", ver, SSHMUX_VER);
1613 goto out;
1614 }
1615 debug2_f("master version %u", ver);
1616 /* No extensions are presently defined */
1617 while (sshbuf_len(m) > 0) {
1618 char *name = NULL;
1619
1620 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
1621 (r = sshbuf_skip_string(m)) != 0) { /* value */
1622 error_fr(r, "parse extension");
1623 goto out;
1624 }
1625 debug2("Unrecognised master extension \"%s\"", name);
1626 free(name);
1627 }
1628 /* success */
1629 ret = 0;
1630 out:
1631 sshbuf_free(m);
1632 return ret;
1633 }
1634
1635 static u_int
mux_client_request_alive(int fd)1636 mux_client_request_alive(int fd)
1637 {
1638 struct sshbuf *m;
1639 char *e;
1640 u_int pid, type, rid;
1641 int r;
1642
1643 debug3_f("entering");
1644
1645 if ((m = sshbuf_new()) == NULL)
1646 fatal_f("sshbuf_new");
1647 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 ||
1648 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1649 fatal_fr(r, "assemble");
1650
1651 if (mux_client_write_packet(fd, m) != 0)
1652 fatal_f("write packet: %s", strerror(errno));
1653
1654 sshbuf_reset(m);
1655
1656 /* Read their reply */
1657 if (mux_client_read_packet(fd, m) != 0) {
1658 sshbuf_free(m);
1659 return 0;
1660 }
1661
1662 if ((r = sshbuf_get_u32(m, &type)) != 0)
1663 fatal_fr(r, "parse type");
1664 if (type != MUX_S_ALIVE) {
1665 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1666 fatal_fr(r, "parse error message");
1667 fatal_f("master returned error: %s", e);
1668 }
1669
1670 if ((r = sshbuf_get_u32(m, &rid)) != 0)
1671 fatal_fr(r, "parse remote ID");
1672 if (rid != muxclient_request_id)
1673 fatal_f("out of sequence reply: my id %u theirs %u",
1674 muxclient_request_id, rid);
1675 if ((r = sshbuf_get_u32(m, &pid)) != 0)
1676 fatal_fr(r, "parse PID");
1677 sshbuf_free(m);
1678
1679 debug3_f("done pid = %u", pid);
1680
1681 muxclient_request_id++;
1682
1683 return pid;
1684 }
1685
1686 static void
mux_client_request_terminate(int fd)1687 mux_client_request_terminate(int fd)
1688 {
1689 struct sshbuf *m;
1690 char *e;
1691 u_int type, rid;
1692 int r;
1693
1694 debug3_f("entering");
1695
1696 if ((m = sshbuf_new()) == NULL)
1697 fatal_f("sshbuf_new");
1698 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 ||
1699 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1700 fatal_fr(r, "request");
1701
1702 if (mux_client_write_packet(fd, m) != 0)
1703 fatal_f("write packet: %s", strerror(errno));
1704
1705 sshbuf_reset(m);
1706
1707 /* Read their reply */
1708 if (mux_client_read_packet(fd, m) != 0) {
1709 /* Remote end exited already */
1710 if (errno == EPIPE) {
1711 sshbuf_free(m);
1712 return;
1713 }
1714 fatal_f("read from master failed: %s", strerror(errno));
1715 }
1716
1717 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1718 (r = sshbuf_get_u32(m, &rid)) != 0)
1719 fatal_fr(r, "parse");
1720 if (rid != muxclient_request_id)
1721 fatal_f("out of sequence reply: my id %u theirs %u",
1722 muxclient_request_id, rid);
1723 switch (type) {
1724 case MUX_S_OK:
1725 break;
1726 case MUX_S_PERMISSION_DENIED:
1727 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1728 fatal_fr(r, "parse error message");
1729 fatal("Master refused termination request: %s", e);
1730 case MUX_S_FAILURE:
1731 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1732 fatal_fr(r, "parse error message");
1733 fatal_f("termination request failed: %s", e);
1734 default:
1735 fatal_f("unexpected response from master 0x%08x", type);
1736 }
1737 sshbuf_free(m);
1738 muxclient_request_id++;
1739 }
1740
1741 static int
mux_client_forward(int fd,int cancel_flag,u_int ftype,struct Forward * fwd)1742 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd)
1743 {
1744 struct sshbuf *m;
1745 char *e, *fwd_desc;
1746 const char *lhost, *chost;
1747 u_int type, rid;
1748 int r;
1749
1750 fwd_desc = format_forward(ftype, fwd);
1751 debug("Requesting %s %s",
1752 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc);
1753 free(fwd_desc);
1754
1755 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD;
1756 if (fwd->listen_path != NULL)
1757 lhost = fwd->listen_path;
1758 else if (fwd->listen_host == NULL)
1759 lhost = "";
1760 else if (*fwd->listen_host == '\0')
1761 lhost = "*";
1762 else
1763 lhost = fwd->listen_host;
1764
1765 if (fwd->connect_path != NULL)
1766 chost = fwd->connect_path;
1767 else if (fwd->connect_host == NULL)
1768 chost = "";
1769 else
1770 chost = fwd->connect_host;
1771
1772 if ((m = sshbuf_new()) == NULL)
1773 fatal_f("sshbuf_new");
1774 if ((r = sshbuf_put_u32(m, type)) != 0 ||
1775 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1776 (r = sshbuf_put_u32(m, ftype)) != 0 ||
1777 (r = sshbuf_put_cstring(m, lhost)) != 0 ||
1778 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 ||
1779 (r = sshbuf_put_cstring(m, chost)) != 0 ||
1780 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0)
1781 fatal_fr(r, "request");
1782
1783 if (mux_client_write_packet(fd, m) != 0)
1784 fatal_f("write packet: %s", strerror(errno));
1785
1786 sshbuf_reset(m);
1787
1788 /* Read their reply */
1789 if (mux_client_read_packet(fd, m) != 0) {
1790 sshbuf_free(m);
1791 return -1;
1792 }
1793
1794 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1795 (r = sshbuf_get_u32(m, &rid)) != 0)
1796 fatal_fr(r, "parse");
1797 if (rid != muxclient_request_id)
1798 fatal_f("out of sequence reply: my id %u theirs %u",
1799 muxclient_request_id, rid);
1800
1801 switch (type) {
1802 case MUX_S_OK:
1803 break;
1804 case MUX_S_REMOTE_PORT:
1805 if (cancel_flag)
1806 fatal_f("got MUX_S_REMOTE_PORT for cancel");
1807 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0)
1808 fatal_fr(r, "parse port");
1809 verbose("Allocated port %u for remote forward to %s:%d",
1810 fwd->allocated_port,
1811 fwd->connect_host ? fwd->connect_host : "",
1812 fwd->connect_port);
1813 if (muxclient_command == SSHMUX_COMMAND_FORWARD)
1814 fprintf(stdout, "%i\n", fwd->allocated_port);
1815 break;
1816 case MUX_S_PERMISSION_DENIED:
1817 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1818 fatal_fr(r, "parse error message");
1819 sshbuf_free(m);
1820 error("Master refused forwarding request: %s", e);
1821 return -1;
1822 case MUX_S_FAILURE:
1823 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1824 fatal_fr(r, "parse error message");
1825 sshbuf_free(m);
1826 error_f("forwarding request failed: %s", e);
1827 return -1;
1828 default:
1829 fatal_f("unexpected response from master 0x%08x", type);
1830 }
1831 sshbuf_free(m);
1832
1833 muxclient_request_id++;
1834 return 0;
1835 }
1836
1837 static int
mux_client_forwards(int fd,int cancel_flag)1838 mux_client_forwards(int fd, int cancel_flag)
1839 {
1840 int i, ret = 0;
1841
1842 debug3_f("%s forwardings: %d local, %d remote",
1843 cancel_flag ? "cancel" : "request",
1844 options.num_local_forwards, options.num_remote_forwards);
1845
1846 /* XXX ExitOnForwardingFailure */
1847 for (i = 0; i < options.num_local_forwards; i++) {
1848 if (mux_client_forward(fd, cancel_flag,
1849 options.local_forwards[i].connect_port == 0 ?
1850 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1851 options.local_forwards + i) != 0)
1852 ret = -1;
1853 }
1854 for (i = 0; i < options.num_remote_forwards; i++) {
1855 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE,
1856 options.remote_forwards + i) != 0)
1857 ret = -1;
1858 }
1859 return ret;
1860 }
1861
1862 static int
mux_client_request_session(int fd)1863 mux_client_request_session(int fd)
1864 {
1865 struct sshbuf *m;
1866 char *e;
1867 const char *term = NULL;
1868 u_int echar, rid, sid, esid, exitval, type, exitval_seen;
1869 extern char **environ;
1870 int r, i, rawmode;
1871
1872 debug3_f("entering");
1873
1874 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1875 error_f("master alive request failed");
1876 return -1;
1877 }
1878
1879 ssh_signal(SIGPIPE, SIG_IGN);
1880
1881 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1)
1882 fatal_f("stdfd_devnull failed");
1883
1884 if ((term = lookup_env_in_list("TERM", options.setenv,
1885 options.num_setenv)) == NULL || *term == '\0')
1886 term = getenv("TERM");
1887
1888 echar = 0xffffffff;
1889 if (options.escape_char != SSH_ESCAPECHAR_NONE)
1890 echar = (u_int)options.escape_char;
1891
1892 if ((m = sshbuf_new()) == NULL)
1893 fatal_f("sshbuf_new");
1894 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 ||
1895 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1896 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
1897 (r = sshbuf_put_u32(m, tty_flag)) != 0 ||
1898 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 ||
1899 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 ||
1900 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 ||
1901 (r = sshbuf_put_u32(m, echar)) != 0 ||
1902 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 ||
1903 (r = sshbuf_put_stringb(m, command)) != 0)
1904 fatal_fr(r, "request");
1905
1906 /* Pass environment */
1907 if (options.num_send_env > 0 && environ != NULL) {
1908 for (i = 0; environ[i] != NULL; i++) {
1909 if (!env_permitted(environ[i]))
1910 continue;
1911 if ((r = sshbuf_put_cstring(m, environ[i])) != 0)
1912 fatal_fr(r, "request sendenv");
1913 }
1914 }
1915 for (i = 0; i < options.num_setenv; i++) {
1916 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0)
1917 fatal_fr(r, "request setenv");
1918 }
1919
1920 if (mux_client_write_packet(fd, m) != 0)
1921 fatal_f("write packet: %s", strerror(errno));
1922
1923 /* Send the stdio file descriptors */
1924 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1925 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1926 mm_send_fd(fd, STDERR_FILENO) == -1)
1927 fatal_f("send fds failed");
1928
1929 debug3_f("session request sent");
1930
1931 /* Read their reply */
1932 sshbuf_reset(m);
1933 if (mux_client_read_packet(fd, m) != 0) {
1934 error_f("read from master failed: %s", strerror(errno));
1935 sshbuf_free(m);
1936 return -1;
1937 }
1938
1939 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1940 (r = sshbuf_get_u32(m, &rid)) != 0)
1941 fatal_fr(r, "parse");
1942 if (rid != muxclient_request_id)
1943 fatal_f("out of sequence reply: my id %u theirs %u",
1944 muxclient_request_id, rid);
1945
1946 switch (type) {
1947 case MUX_S_SESSION_OPENED:
1948 if ((r = sshbuf_get_u32(m, &sid)) != 0)
1949 fatal_fr(r, "parse session ID");
1950 debug_f("master session id: %u", sid);
1951 break;
1952 case MUX_S_PERMISSION_DENIED:
1953 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1954 fatal_fr(r, "parse error message");
1955 error("Master refused session request: %s", e);
1956 sshbuf_free(m);
1957 return -1;
1958 case MUX_S_FAILURE:
1959 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1960 fatal_fr(r, "parse error message");
1961 error_f("session request failed: %s", e);
1962 sshbuf_free(m);
1963 return -1;
1964 default:
1965 sshbuf_free(m);
1966 error_f("unexpected response from master 0x%08x", type);
1967 return -1;
1968 }
1969 muxclient_request_id++;
1970
1971 if (pledge("stdio proc tty", NULL) == -1)
1972 fatal_f("pledge(): %s", strerror(errno));
1973 platform_pledge_mux();
1974
1975 ssh_signal(SIGHUP, control_client_sighandler);
1976 ssh_signal(SIGINT, control_client_sighandler);
1977 ssh_signal(SIGTERM, control_client_sighandler);
1978 ssh_signal(SIGWINCH, control_client_sigrelay);
1979
1980 rawmode = tty_flag;
1981 if (tty_flag)
1982 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1983
1984 /*
1985 * Stick around until the controlee closes the client_fd.
1986 * Before it does, it is expected to write an exit message.
1987 * This process must read the value and wait for the closure of
1988 * the client_fd; if this one closes early, the multiplex master will
1989 * terminate early too (possibly losing data).
1990 */
1991 for (exitval = 255, exitval_seen = 0;;) {
1992 sshbuf_reset(m);
1993 if (mux_client_read_packet(fd, m) != 0)
1994 break;
1995 if ((r = sshbuf_get_u32(m, &type)) != 0)
1996 fatal_fr(r, "parse type");
1997 switch (type) {
1998 case MUX_S_TTY_ALLOC_FAIL:
1999 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2000 fatal_fr(r, "parse session ID");
2001 if (esid != sid)
2002 fatal_f("tty alloc fail on unknown session: "
2003 "my id %u theirs %u", sid, esid);
2004 leave_raw_mode(options.request_tty ==
2005 REQUEST_TTY_FORCE);
2006 rawmode = 0;
2007 continue;
2008 case MUX_S_EXIT_MESSAGE:
2009 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2010 fatal_fr(r, "parse session ID");
2011 if (esid != sid)
2012 fatal_f("exit on unknown session: "
2013 "my id %u theirs %u", sid, esid);
2014 if (exitval_seen)
2015 fatal_f("exitval sent twice");
2016 if ((r = sshbuf_get_u32(m, &exitval)) != 0)
2017 fatal_fr(r, "parse exitval");
2018 exitval_seen = 1;
2019 continue;
2020 default:
2021 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2022 fatal_fr(r, "parse error message");
2023 fatal_f("master returned error: %s", e);
2024 }
2025 }
2026
2027 close(fd);
2028 if (rawmode)
2029 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2030
2031 if (muxclient_terminate) {
2032 debug2("Exiting on signal: %s", strsignal(muxclient_terminate));
2033 exitval = 255;
2034 } else if (!exitval_seen) {
2035 debug2("Control master terminated unexpectedly");
2036 exitval = 255;
2037 } else
2038 debug2("Received exit status from master %d", exitval);
2039
2040 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
2041 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
2042
2043 exit(exitval);
2044 }
2045
2046 static int
mux_client_proxy(int fd)2047 mux_client_proxy(int fd)
2048 {
2049 struct sshbuf *m;
2050 char *e;
2051 u_int type, rid;
2052 int r;
2053
2054 if ((m = sshbuf_new()) == NULL)
2055 fatal_f("sshbuf_new");
2056 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 ||
2057 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2058 fatal_fr(r, "request");
2059 if (mux_client_write_packet(fd, m) != 0)
2060 fatal_f("write packet: %s", strerror(errno));
2061
2062 sshbuf_reset(m);
2063
2064 /* Read their reply */
2065 if (mux_client_read_packet(fd, m) != 0) {
2066 sshbuf_free(m);
2067 return 0;
2068 }
2069 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2070 (r = sshbuf_get_u32(m, &rid)) != 0)
2071 fatal_fr(r, "parse");
2072 if (rid != muxclient_request_id)
2073 fatal_f("out of sequence reply: my id %u theirs %u",
2074 muxclient_request_id, rid);
2075 if (type != MUX_S_PROXY) {
2076 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2077 fatal_fr(r, "parse error message");
2078 fatal_f("master returned error: %s", e);
2079 }
2080 sshbuf_free(m);
2081
2082 debug3_f("done");
2083 muxclient_request_id++;
2084 return 0;
2085 }
2086
2087 static int
mux_client_request_stdio_fwd(int fd)2088 mux_client_request_stdio_fwd(int fd)
2089 {
2090 struct sshbuf *m;
2091 char *e;
2092 u_int type, rid, sid;
2093 int r;
2094
2095 debug3_f("entering");
2096
2097 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
2098 error_f("master alive request failed");
2099 return -1;
2100 }
2101
2102 ssh_signal(SIGPIPE, SIG_IGN);
2103
2104 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1)
2105 fatal_f("stdfd_devnull failed");
2106
2107 if ((m = sshbuf_new()) == NULL)
2108 fatal_f("sshbuf_new");
2109 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 ||
2110 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
2111 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
2112 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 ||
2113 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0)
2114 fatal_fr(r, "request");
2115
2116 if (mux_client_write_packet(fd, m) != 0)
2117 fatal_f("write packet: %s", strerror(errno));
2118
2119 /* Send the stdio file descriptors */
2120 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
2121 mm_send_fd(fd, STDOUT_FILENO) == -1)
2122 fatal_f("send fds failed");
2123
2124 if (pledge("stdio proc tty", NULL) == -1)
2125 fatal_f("pledge(): %s", strerror(errno));
2126 platform_pledge_mux();
2127
2128 debug3_f("stdio forward request sent");
2129
2130 /* Read their reply */
2131 sshbuf_reset(m);
2132
2133 if (mux_client_read_packet(fd, m) != 0) {
2134 error_f("read from master failed: %s", strerror(errno));
2135 sshbuf_free(m);
2136 return -1;
2137 }
2138
2139 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2140 (r = sshbuf_get_u32(m, &rid)) != 0)
2141 fatal_fr(r, "parse");
2142 if (rid != muxclient_request_id)
2143 fatal_f("out of sequence reply: my id %u theirs %u",
2144 muxclient_request_id, rid);
2145 switch (type) {
2146 case MUX_S_SESSION_OPENED:
2147 if ((r = sshbuf_get_u32(m, &sid)) != 0)
2148 fatal_fr(r, "parse session ID");
2149 debug_f("master session id: %u", sid);
2150 break;
2151 case MUX_S_PERMISSION_DENIED:
2152 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2153 fatal_fr(r, "parse error message");
2154 sshbuf_free(m);
2155 fatal("Master refused stdio forwarding request: %s", e);
2156 case MUX_S_FAILURE:
2157 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2158 fatal_fr(r, "parse error message");
2159 sshbuf_free(m);
2160 fatal("Stdio forwarding request failed: %s", e);
2161 default:
2162 sshbuf_free(m);
2163 error_f("unexpected response from master 0x%08x", type);
2164 return -1;
2165 }
2166 muxclient_request_id++;
2167
2168 ssh_signal(SIGHUP, control_client_sighandler);
2169 ssh_signal(SIGINT, control_client_sighandler);
2170 ssh_signal(SIGTERM, control_client_sighandler);
2171 ssh_signal(SIGWINCH, control_client_sigrelay);
2172
2173 /*
2174 * Stick around until the controlee closes the client_fd.
2175 */
2176 sshbuf_reset(m);
2177 if (mux_client_read_packet(fd, m) != 0) {
2178 if (errno == EPIPE ||
2179 (errno == EINTR && muxclient_terminate != 0))
2180 return 0;
2181 fatal_f("mux_client_read_packet: %s", strerror(errno));
2182 }
2183 fatal_f("master returned unexpected message %u", type);
2184 }
2185
2186 static void
mux_client_request_stop_listening(int fd)2187 mux_client_request_stop_listening(int fd)
2188 {
2189 struct sshbuf *m;
2190 char *e;
2191 u_int type, rid;
2192 int r;
2193
2194 debug3_f("entering");
2195
2196 if ((m = sshbuf_new()) == NULL)
2197 fatal_f("sshbuf_new");
2198 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 ||
2199 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2200 fatal_fr(r, "request");
2201
2202 if (mux_client_write_packet(fd, m) != 0)
2203 fatal_f("write packet: %s", strerror(errno));
2204
2205 sshbuf_reset(m);
2206
2207 /* Read their reply */
2208 if (mux_client_read_packet(fd, m) != 0)
2209 fatal_f("read from master failed: %s", strerror(errno));
2210
2211 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2212 (r = sshbuf_get_u32(m, &rid)) != 0)
2213 fatal_fr(r, "parse");
2214 if (rid != muxclient_request_id)
2215 fatal_f("out of sequence reply: my id %u theirs %u",
2216 muxclient_request_id, rid);
2217
2218 switch (type) {
2219 case MUX_S_OK:
2220 break;
2221 case MUX_S_PERMISSION_DENIED:
2222 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2223 fatal_fr(r, "parse error message");
2224 fatal("Master refused stop listening request: %s", e);
2225 case MUX_S_FAILURE:
2226 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2227 fatal_fr(r, "parse error message");
2228 fatal_f("stop listening request failed: %s", e);
2229 default:
2230 fatal_f("unexpected response from master 0x%08x", type);
2231 }
2232 sshbuf_free(m);
2233 muxclient_request_id++;
2234 }
2235
2236 /* Multiplex client main loop. */
2237 int
muxclient(const char * path)2238 muxclient(const char *path)
2239 {
2240 struct sockaddr_un addr;
2241 int sock;
2242 u_int pid;
2243
2244 if (muxclient_command == 0) {
2245 if (options.stdio_forward_host != NULL)
2246 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
2247 else
2248 muxclient_command = SSHMUX_COMMAND_OPEN;
2249 }
2250
2251 switch (options.control_master) {
2252 case SSHCTL_MASTER_AUTO:
2253 case SSHCTL_MASTER_AUTO_ASK:
2254 debug("auto-mux: Trying existing master");
2255 /* FALLTHROUGH */
2256 case SSHCTL_MASTER_NO:
2257 break;
2258 default:
2259 return -1;
2260 }
2261
2262 memset(&addr, '\0', sizeof(addr));
2263 addr.sun_family = AF_UNIX;
2264
2265 if (strlcpy(addr.sun_path, path,
2266 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
2267 fatal("ControlPath too long ('%s' >= %u bytes)", path,
2268 (unsigned int)sizeof(addr.sun_path));
2269
2270 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
2271 fatal_f("socket(): %s", strerror(errno));
2272
2273 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
2274 switch (muxclient_command) {
2275 case SSHMUX_COMMAND_OPEN:
2276 case SSHMUX_COMMAND_STDIO_FWD:
2277 break;
2278 default:
2279 fatal("Control socket connect(%.100s): %s", path,
2280 strerror(errno));
2281 }
2282 if (errno == ECONNREFUSED &&
2283 options.control_master != SSHCTL_MASTER_NO) {
2284 debug("Stale control socket %.100s, unlinking", path);
2285 unlink(path);
2286 } else if (errno == ENOENT) {
2287 debug("Control socket \"%.100s\" does not exist", path);
2288 } else {
2289 error("Control socket connect(%.100s): %s", path,
2290 strerror(errno));
2291 }
2292 close(sock);
2293 return -1;
2294 }
2295 set_nonblock(sock);
2296
2297 if (mux_client_hello_exchange(sock) != 0) {
2298 error_f("master hello exchange failed");
2299 close(sock);
2300 return -1;
2301 }
2302
2303 switch (muxclient_command) {
2304 case SSHMUX_COMMAND_ALIVE_CHECK:
2305 if ((pid = mux_client_request_alive(sock)) == 0)
2306 fatal_f("master alive check failed");
2307 fprintf(stderr, "Master running (pid=%u)\r\n", pid);
2308 exit(0);
2309 case SSHMUX_COMMAND_TERMINATE:
2310 mux_client_request_terminate(sock);
2311 if (options.log_level != SYSLOG_LEVEL_QUIET)
2312 fprintf(stderr, "Exit request sent.\r\n");
2313 exit(0);
2314 case SSHMUX_COMMAND_FORWARD:
2315 if (mux_client_forwards(sock, 0) != 0)
2316 fatal_f("master forward request failed");
2317 exit(0);
2318 case SSHMUX_COMMAND_OPEN:
2319 if (mux_client_forwards(sock, 0) != 0) {
2320 error_f("master forward request failed");
2321 return -1;
2322 }
2323 mux_client_request_session(sock);
2324 return -1;
2325 case SSHMUX_COMMAND_STDIO_FWD:
2326 mux_client_request_stdio_fwd(sock);
2327 exit(0);
2328 case SSHMUX_COMMAND_STOP:
2329 mux_client_request_stop_listening(sock);
2330 if (options.log_level != SYSLOG_LEVEL_QUIET)
2331 fprintf(stderr, "Stop listening request sent.\r\n");
2332 exit(0);
2333 case SSHMUX_COMMAND_CANCEL_FWD:
2334 if (mux_client_forwards(sock, 1) != 0)
2335 error_f("master cancel forward request failed");
2336 exit(0);
2337 case SSHMUX_COMMAND_PROXY:
2338 mux_client_proxy(sock);
2339 return (sock);
2340 default:
2341 fatal("unrecognised muxclient_command %d", muxclient_command);
2342 }
2343 }
2344