1 /* $OpenBSD: mux.c,v 1.101 2023/11/23 03:37:05 dtucker 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 <limits.h>
30 #include <signal.h>
31 #include <stdarg.h>
32 #include <stddef.h>
33 #include <stdlib.h>
34 #include <stdio.h>
35 #include <string.h>
36 #include <unistd.h>
37 #ifdef HAVE_PATHS_H
38 #include <paths.h>
39 #endif
40
41 #ifdef HAVE_POLL_H
42 #include <poll.h>
43 #else
44 # ifdef HAVE_SYS_POLL_H
45 # include <sys/poll.h>
46 # endif
47 #endif
48
49 #ifdef HAVE_UTIL_H
50 # include <util.h>
51 #endif
52
53 #include "openbsd-compat/sys-queue.h"
54 #include "xmalloc.h"
55 #include "log.h"
56 #include "ssh.h"
57 #include "ssh2.h"
58 #include "pathnames.h"
59 #include "misc.h"
60 #include "match.h"
61 #include "sshbuf.h"
62 #include "channels.h"
63 #include "msg.h"
64 #include "packet.h"
65 #include "monitor_fdpass.h"
66 #include "sshpty.h"
67 #include "sshkey.h"
68 #include "readconf.h"
69 #include "clientloop.h"
70 #include "ssherr.h"
71 #include "misc.h"
72
73 /* from ssh.c */
74 extern int tty_flag;
75 extern Options options;
76 extern char *host;
77 extern struct sshbuf *command;
78 extern volatile sig_atomic_t quit_pending;
79
80 /* Context for session open confirmation callback */
81 struct mux_session_confirm_ctx {
82 u_int want_tty;
83 u_int want_subsys;
84 u_int want_x_fwd;
85 u_int want_agent_fwd;
86 struct sshbuf *cmd;
87 char *term;
88 struct termios tio;
89 char **env;
90 u_int rid;
91 };
92
93 /* Context for stdio fwd open confirmation callback */
94 struct mux_stdio_confirm_ctx {
95 u_int rid;
96 };
97
98 /* Context for global channel callback */
99 struct mux_channel_confirm_ctx {
100 u_int cid; /* channel id */
101 u_int rid; /* request id */
102 int fid; /* forward id */
103 };
104
105 /* fd to control socket */
106 int muxserver_sock = -1;
107
108 /* client request id */
109 u_int muxclient_request_id = 0;
110
111 /* Multiplexing control command */
112 u_int muxclient_command = 0;
113
114 /* Set when signalled. */
115 static volatile sig_atomic_t muxclient_terminate = 0;
116
117 /* PID of multiplex server */
118 static u_int muxserver_pid = 0;
119
120 static Channel *mux_listener_channel = NULL;
121
122 struct mux_master_state {
123 int hello_rcvd;
124 };
125
126 /* mux protocol messages */
127 #define MUX_MSG_HELLO 0x00000001
128 #define MUX_C_NEW_SESSION 0x10000002
129 #define MUX_C_ALIVE_CHECK 0x10000004
130 #define MUX_C_TERMINATE 0x10000005
131 #define MUX_C_OPEN_FWD 0x10000006
132 #define MUX_C_CLOSE_FWD 0x10000007
133 #define MUX_C_NEW_STDIO_FWD 0x10000008
134 #define MUX_C_STOP_LISTENING 0x10000009
135 #define MUX_C_PROXY 0x1000000f
136 #define MUX_S_OK 0x80000001
137 #define MUX_S_PERMISSION_DENIED 0x80000002
138 #define MUX_S_FAILURE 0x80000003
139 #define MUX_S_EXIT_MESSAGE 0x80000004
140 #define MUX_S_ALIVE 0x80000005
141 #define MUX_S_SESSION_OPENED 0x80000006
142 #define MUX_S_REMOTE_PORT 0x80000007
143 #define MUX_S_TTY_ALLOC_FAIL 0x80000008
144 #define MUX_S_PROXY 0x8000000f
145
146 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
147 #define MUX_FWD_LOCAL 1
148 #define MUX_FWD_REMOTE 2
149 #define MUX_FWD_DYNAMIC 3
150
151 static void mux_session_confirm(struct ssh *, int, int, void *);
152 static void mux_stdio_confirm(struct ssh *, int, int, void *);
153
154 static int mux_master_process_hello(struct ssh *, u_int,
155 Channel *, struct sshbuf *, struct sshbuf *);
156 static int mux_master_process_new_session(struct ssh *, u_int,
157 Channel *, struct sshbuf *, struct sshbuf *);
158 static int mux_master_process_alive_check(struct ssh *, u_int,
159 Channel *, struct sshbuf *, struct sshbuf *);
160 static int mux_master_process_terminate(struct ssh *, u_int,
161 Channel *, struct sshbuf *, struct sshbuf *);
162 static int mux_master_process_open_fwd(struct ssh *, u_int,
163 Channel *, struct sshbuf *, struct sshbuf *);
164 static int mux_master_process_close_fwd(struct ssh *, u_int,
165 Channel *, struct sshbuf *, struct sshbuf *);
166 static int mux_master_process_stdio_fwd(struct ssh *, u_int,
167 Channel *, struct sshbuf *, struct sshbuf *);
168 static int mux_master_process_stop_listening(struct ssh *, u_int,
169 Channel *, struct sshbuf *, struct sshbuf *);
170 static int mux_master_process_proxy(struct ssh *, u_int,
171 Channel *, struct sshbuf *, struct sshbuf *);
172
173 static const struct {
174 u_int type;
175 int (*handler)(struct ssh *, u_int, Channel *,
176 struct sshbuf *, struct sshbuf *);
177 } mux_master_handlers[] = {
178 { MUX_MSG_HELLO, mux_master_process_hello },
179 { MUX_C_NEW_SESSION, mux_master_process_new_session },
180 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check },
181 { MUX_C_TERMINATE, mux_master_process_terminate },
182 { MUX_C_OPEN_FWD, mux_master_process_open_fwd },
183 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd },
184 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd },
185 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening },
186 { MUX_C_PROXY, mux_master_process_proxy },
187 { 0, NULL }
188 };
189
190 /* Cleanup callback fired on closure of mux client _session_ channel */
191 static void
mux_master_session_cleanup_cb(struct ssh * ssh,int cid,int force,void * unused)192 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused)
193 {
194 Channel *cc, *c = channel_by_id(ssh, cid);
195
196 debug3_f("entering for channel %d", cid);
197 if (c == NULL)
198 fatal_f("channel_by_id(%i) == NULL", cid);
199 if (c->ctl_chan != -1) {
200 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
201 fatal_f("channel %d missing control channel %d",
202 c->self, c->ctl_chan);
203 c->ctl_chan = -1;
204 cc->remote_id = 0;
205 cc->have_remote_id = 0;
206 chan_rcvd_oclose(ssh, cc);
207 }
208 channel_cancel_cleanup(ssh, c->self);
209 }
210
211 /* Cleanup callback fired on closure of mux client _control_ channel */
212 static void
mux_master_control_cleanup_cb(struct ssh * ssh,int cid,int force,void * unused)213 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, 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(const char * env)243 env_permitted(const char *env)
244 {
245 u_int i;
246 int ret;
247 char name[1024], *cp;
248
249 if ((cp = strchr(env, '=')) == NULL || cp == env)
250 return 0;
251 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
252 if (ret <= 0 || (size_t)ret >= sizeof(name)) {
253 error_f("name '%.100s...' too long", env);
254 return 0;
255 }
256
257 for (i = 0; i < options.num_send_env; i++)
258 if (match_pattern(name, options.send_env[i]))
259 return 1;
260
261 return 0;
262 }
263
264 /* Mux master protocol message handlers */
265
266 static int
mux_master_process_hello(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)267 mux_master_process_hello(struct ssh *ssh, u_int rid,
268 Channel *c, struct sshbuf *m, struct sshbuf *reply)
269 {
270 u_int ver;
271 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
272 int r;
273
274 if (state == NULL)
275 fatal_f("channel %d: c->mux_ctx == NULL", c->self);
276 if (state->hello_rcvd) {
277 error_f("HELLO received twice");
278 return -1;
279 }
280 if ((r = sshbuf_get_u32(m, &ver)) != 0) {
281 error_fr(r, "parse");
282 return -1;
283 }
284 if (ver != SSHMUX_VER) {
285 error_f("unsupported multiplexing protocol version %u "
286 "(expected %u)", ver, SSHMUX_VER);
287 return -1;
288 }
289 debug2_f("channel %d client version %u", c->self, ver);
290
291 /* No extensions are presently defined */
292 while (sshbuf_len(m) > 0) {
293 char *name = NULL;
294 size_t value_len = 0;
295
296 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
297 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) {
298 error_fr(r, "parse extension");
299 return -1;
300 }
301 debug2_f("Unrecognised extension \"%s\" length %zu",
302 name, value_len);
303 free(name);
304 }
305 state->hello_rcvd = 1;
306 return 0;
307 }
308
309 /* Enqueue a "ok" response to the reply buffer */
310 static void
reply_ok(struct sshbuf * reply,u_int rid)311 reply_ok(struct sshbuf *reply, u_int rid)
312 {
313 int r;
314
315 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 ||
316 (r = sshbuf_put_u32(reply, rid)) != 0)
317 fatal_fr(r, "reply");
318 }
319
320 /* Enqueue an error response to the reply buffer */
321 static void
reply_error(struct sshbuf * reply,u_int type,u_int rid,const char * msg)322 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg)
323 {
324 int r;
325
326 if ((r = sshbuf_put_u32(reply, type)) != 0 ||
327 (r = sshbuf_put_u32(reply, rid)) != 0 ||
328 (r = sshbuf_put_cstring(reply, msg)) != 0)
329 fatal_fr(r, "reply");
330 }
331
332 static int
mux_master_process_new_session(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)333 mux_master_process_new_session(struct ssh *ssh, u_int rid,
334 Channel *c, struct sshbuf *m, struct sshbuf *reply)
335 {
336 Channel *nc;
337 struct mux_session_confirm_ctx *cctx;
338 char *cmd, *cp;
339 u_int i, j, env_len, escape_char, window, packetmax;
340 int r, new_fd[3];
341
342 /* Reply for SSHMUX_COMMAND_OPEN */
343 cctx = xcalloc(1, sizeof(*cctx));
344 cctx->term = NULL;
345 cctx->rid = rid;
346 cmd = NULL;
347 cctx->env = NULL;
348 env_len = 0;
349 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
350 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 ||
351 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 ||
352 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 ||
353 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 ||
354 (r = sshbuf_get_u32(m, &escape_char)) != 0 ||
355 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 ||
356 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) {
357 malf:
358 free(cmd);
359 for (j = 0; j < env_len; j++)
360 free(cctx->env[j]);
361 free(cctx->env);
362 free(cctx->term);
363 free(cctx);
364 error_f("malformed message");
365 return -1;
366 }
367
368 #define MUX_MAX_ENV_VARS 4096
369 while (sshbuf_len(m) > 0) {
370 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0)
371 goto malf;
372 if (!env_permitted(cp)) {
373 free(cp);
374 continue;
375 }
376 cctx->env = xreallocarray(cctx->env, env_len + 2,
377 sizeof(*cctx->env));
378 cctx->env[env_len++] = cp;
379 cctx->env[env_len] = NULL;
380 if (env_len > MUX_MAX_ENV_VARS) {
381 error_f(">%d environment variables received, "
382 "ignoring additional", MUX_MAX_ENV_VARS);
383 break;
384 }
385 }
386
387 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, "
388 "term \"%s\", cmd \"%s\", env %u", c->self,
389 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
390 cctx->want_subsys, cctx->term, cmd, env_len);
391
392 if ((cctx->cmd = sshbuf_new()) == NULL)
393 fatal_f("sshbuf_new");
394 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0)
395 fatal_fr(r, "sshbuf_put");
396 free(cmd);
397 cmd = NULL;
398
399 /* Gather fds from client */
400 for(i = 0; i < 3; i++) {
401 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
402 error_f("failed to receive fd %d from client", i);
403 for (j = 0; j < i; j++)
404 close(new_fd[j]);
405 for (j = 0; j < env_len; j++)
406 free(cctx->env[j]);
407 free(cctx->env);
408 free(cctx->term);
409 sshbuf_free(cctx->cmd);
410 free(cctx);
411 reply_error(reply, MUX_S_FAILURE, rid,
412 "did not receive file descriptors");
413 return -1;
414 }
415 }
416
417 debug3_f("got fds stdin %d, stdout %d, stderr %d",
418 new_fd[0], new_fd[1], new_fd[2]);
419
420 /* XXX support multiple child sessions in future */
421 if (c->have_remote_id) {
422 debug2_f("session already open");
423 reply_error(reply, MUX_S_FAILURE, rid,
424 "Multiple sessions not supported");
425 cleanup:
426 close(new_fd[0]);
427 close(new_fd[1]);
428 close(new_fd[2]);
429 free(cctx->term);
430 if (env_len != 0) {
431 for (i = 0; i < env_len; i++)
432 free(cctx->env[i]);
433 free(cctx->env);
434 }
435 sshbuf_free(cctx->cmd);
436 free(cctx);
437 return 0;
438 }
439
440 if (options.control_master == SSHCTL_MASTER_ASK ||
441 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
442 if (!ask_permission("Allow shared connection to %s? ", host)) {
443 debug2_f("session refused by user");
444 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
445 "Permission denied");
446 goto cleanup;
447 }
448 }
449
450 /* Try to pick up ttymodes from client before it goes raw */
451 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
452 error_f("tcgetattr: %s", strerror(errno));
453
454 window = CHAN_SES_WINDOW_DEFAULT;
455 packetmax = CHAN_SES_PACKET_DEFAULT;
456 if (cctx->want_tty) {
457 window >>= 1;
458 packetmax >>= 1;
459 }
460
461 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
462 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
463 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO);
464
465 nc->ctl_chan = c->self; /* link session -> control channel */
466 c->remote_id = nc->self; /* link control -> session channel */
467 c->have_remote_id = 1;
468
469 if (cctx->want_tty && escape_char != 0xffffffff) {
470 channel_register_filter(ssh, nc->self,
471 client_simple_escape_filter, NULL,
472 client_filter_cleanup,
473 client_new_escape_filter_ctx((int)escape_char));
474 }
475
476 debug2_f("channel_new: %d linked to control channel %d",
477 nc->self, nc->ctl_chan);
478
479 channel_send_open(ssh, nc->self);
480 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx);
481 c->mux_pause = 1; /* stop handling messages until open_confirm done */
482 channel_register_cleanup(ssh, nc->self,
483 mux_master_session_cleanup_cb, 1);
484
485 /* reply is deferred, sent by mux_session_confirm */
486 return 0;
487 }
488
489 static int
mux_master_process_alive_check(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)490 mux_master_process_alive_check(struct ssh *ssh, u_int rid,
491 Channel *c, struct sshbuf *m, struct sshbuf *reply)
492 {
493 int r;
494
495 debug2_f("channel %d: alive check", c->self);
496
497 /* prepare reply */
498 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 ||
499 (r = sshbuf_put_u32(reply, rid)) != 0 ||
500 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0)
501 fatal_fr(r, "reply");
502
503 return 0;
504 }
505
506 static int
mux_master_process_terminate(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)507 mux_master_process_terminate(struct ssh *ssh, u_int rid,
508 Channel *c, struct sshbuf *m, struct sshbuf *reply)
509 {
510 debug2_f("channel %d: terminate request", c->self);
511
512 if (options.control_master == SSHCTL_MASTER_ASK ||
513 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
514 if (!ask_permission("Terminate shared connection to %s? ",
515 host)) {
516 debug2_f("termination refused by user");
517 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
518 "Permission denied");
519 return 0;
520 }
521 }
522
523 quit_pending = 1;
524 reply_ok(reply, rid);
525 /* XXX exit happens too soon - message never makes it to client */
526 return 0;
527 }
528
529 static char *
format_forward(u_int ftype,struct Forward * fwd)530 format_forward(u_int ftype, struct Forward *fwd)
531 {
532 char *ret;
533
534 switch (ftype) {
535 case MUX_FWD_LOCAL:
536 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
537 (fwd->listen_path != NULL) ? fwd->listen_path :
538 (fwd->listen_host == NULL) ?
539 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
540 fwd->listen_host, fwd->listen_port,
541 (fwd->connect_path != NULL) ? fwd->connect_path :
542 fwd->connect_host, fwd->connect_port);
543 break;
544 case MUX_FWD_DYNAMIC:
545 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
546 (fwd->listen_host == NULL) ?
547 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
548 fwd->listen_host, fwd->listen_port);
549 break;
550 case MUX_FWD_REMOTE:
551 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
552 (fwd->listen_path != NULL) ? fwd->listen_path :
553 (fwd->listen_host == NULL) ?
554 "LOCALHOST" : fwd->listen_host,
555 fwd->listen_port,
556 (fwd->connect_path != NULL) ? fwd->connect_path :
557 fwd->connect_host, fwd->connect_port);
558 break;
559 default:
560 fatal_f("unknown forward type %u", ftype);
561 }
562 return ret;
563 }
564
565 static int
compare_host(const char * a,const char * b)566 compare_host(const char *a, const char *b)
567 {
568 if (a == NULL && b == NULL)
569 return 1;
570 if (a == NULL || b == NULL)
571 return 0;
572 return strcmp(a, b) == 0;
573 }
574
575 static int
compare_forward(struct Forward * a,struct Forward * b)576 compare_forward(struct Forward *a, struct Forward *b)
577 {
578 if (!compare_host(a->listen_host, b->listen_host))
579 return 0;
580 if (!compare_host(a->listen_path, b->listen_path))
581 return 0;
582 if (a->listen_port != b->listen_port)
583 return 0;
584 if (!compare_host(a->connect_host, b->connect_host))
585 return 0;
586 if (!compare_host(a->connect_path, b->connect_path))
587 return 0;
588 if (a->connect_port != b->connect_port)
589 return 0;
590
591 return 1;
592 }
593
594 static void
mux_confirm_remote_forward(struct ssh * ssh,int type,u_int32_t seq,void * ctxt)595 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
596 {
597 struct mux_channel_confirm_ctx *fctx = ctxt;
598 char *failmsg = NULL;
599 struct Forward *rfwd;
600 Channel *c;
601 struct sshbuf *out;
602 u_int port;
603 int r;
604
605 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) {
606 /* no channel for reply */
607 error_f("unknown channel");
608 return;
609 }
610 if ((out = sshbuf_new()) == NULL)
611 fatal_f("sshbuf_new");
612 if (fctx->fid >= options.num_remote_forwards ||
613 (options.remote_forwards[fctx->fid].connect_path == NULL &&
614 options.remote_forwards[fctx->fid].connect_host == NULL)) {
615 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
616 goto fail;
617 }
618 rfwd = &options.remote_forwards[fctx->fid];
619 debug_f("%s for: listen %d, connect %s:%d",
620 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
621 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
622 rfwd->connect_host, rfwd->connect_port);
623 if (type == SSH2_MSG_REQUEST_SUCCESS) {
624 if (rfwd->listen_port == 0) {
625 if ((r = sshpkt_get_u32(ssh, &port)) != 0)
626 fatal_fr(r, "parse port");
627 if (port > 65535) {
628 fatal("Invalid allocated port %u for "
629 "mux remote forward to %s:%d", port,
630 rfwd->connect_host, rfwd->connect_port);
631 }
632 rfwd->allocated_port = (int)port;
633 debug("Allocated port %u for mux remote forward"
634 " to %s:%d", rfwd->allocated_port,
635 rfwd->connect_host, rfwd->connect_port);
636 if ((r = sshbuf_put_u32(out,
637 MUX_S_REMOTE_PORT)) != 0 ||
638 (r = sshbuf_put_u32(out, fctx->rid)) != 0 ||
639 (r = sshbuf_put_u32(out,
640 rfwd->allocated_port)) != 0)
641 fatal_fr(r, "reply");
642 channel_update_permission(ssh, rfwd->handle,
643 rfwd->allocated_port);
644 } else {
645 reply_ok(out, fctx->rid);
646 }
647 goto out;
648 } else {
649 if (rfwd->listen_port == 0)
650 channel_update_permission(ssh, rfwd->handle, -1);
651 if (rfwd->listen_path != NULL)
652 xasprintf(&failmsg, "remote port forwarding failed for "
653 "listen path %s", rfwd->listen_path);
654 else
655 xasprintf(&failmsg, "remote port forwarding failed for "
656 "listen port %d", rfwd->listen_port);
657
658 debug2_f("clearing registered forwarding for listen %d, "
659 "connect %s:%d", rfwd->listen_port,
660 rfwd->connect_path ? rfwd->connect_path :
661 rfwd->connect_host, rfwd->connect_port);
662
663 free(rfwd->listen_host);
664 free(rfwd->listen_path);
665 free(rfwd->connect_host);
666 free(rfwd->connect_path);
667 memset(rfwd, 0, sizeof(*rfwd));
668 }
669 fail:
670 error_f("%s", failmsg);
671 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg);
672 free(failmsg);
673 out:
674 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
675 fatal_fr(r, "enqueue");
676 sshbuf_free(out);
677 if (c->mux_pause <= 0)
678 fatal_f("mux_pause %d", c->mux_pause);
679 c->mux_pause = 0; /* start processing messages again */
680 }
681
682 static int
mux_master_process_open_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)683 mux_master_process_open_fwd(struct ssh *ssh, u_int rid,
684 Channel *c, struct sshbuf *m, struct sshbuf *reply)
685 {
686 struct Forward fwd;
687 char *fwd_desc = NULL;
688 char *listen_addr, *connect_addr;
689 u_int ftype;
690 u_int lport, cport;
691 int r, i, ret = 0, freefwd = 1;
692
693 memset(&fwd, 0, sizeof(fwd));
694
695 /* XXX - lport/cport check redundant */
696 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
697 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
698 (r = sshbuf_get_u32(m, &lport)) != 0 ||
699 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
700 (r = sshbuf_get_u32(m, &cport)) != 0 ||
701 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
702 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
703 error_f("malformed message");
704 ret = -1;
705 goto out;
706 }
707 if (*listen_addr == '\0') {
708 free(listen_addr);
709 listen_addr = NULL;
710 }
711 if (*connect_addr == '\0') {
712 free(connect_addr);
713 connect_addr = NULL;
714 }
715
716 memset(&fwd, 0, sizeof(fwd));
717 fwd.listen_port = lport;
718 if (fwd.listen_port == PORT_STREAMLOCAL)
719 fwd.listen_path = listen_addr;
720 else
721 fwd.listen_host = listen_addr;
722 fwd.connect_port = cport;
723 if (fwd.connect_port == PORT_STREAMLOCAL)
724 fwd.connect_path = connect_addr;
725 else
726 fwd.connect_host = connect_addr;
727
728 debug2_f("channel %d: request %s", c->self,
729 (fwd_desc = format_forward(ftype, &fwd)));
730
731 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
732 ftype != MUX_FWD_DYNAMIC) {
733 logit_f("invalid forwarding type %u", ftype);
734 invalid:
735 free(listen_addr);
736 free(connect_addr);
737 reply_error(reply, MUX_S_FAILURE, rid,
738 "Invalid forwarding request");
739 return 0;
740 }
741 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) {
742 logit_f("streamlocal and dynamic forwards "
743 "are mutually exclusive");
744 goto invalid;
745 }
746 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) {
747 logit_f("invalid listen port %u", fwd.listen_port);
748 goto invalid;
749 }
750 if ((fwd.connect_port != PORT_STREAMLOCAL &&
751 fwd.connect_port >= 65536) ||
752 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE &&
753 fwd.connect_port == 0)) {
754 logit_f("invalid connect port %u",
755 fwd.connect_port);
756 goto invalid;
757 }
758 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL &&
759 fwd.connect_path == NULL) {
760 logit_f("missing connect host");
761 goto invalid;
762 }
763
764 /* Skip forwards that have already been requested */
765 switch (ftype) {
766 case MUX_FWD_LOCAL:
767 case MUX_FWD_DYNAMIC:
768 for (i = 0; i < options.num_local_forwards; i++) {
769 if (compare_forward(&fwd,
770 options.local_forwards + i)) {
771 exists:
772 debug2_f("found existing forwarding");
773 reply_ok(reply, rid);
774 goto out;
775 }
776 }
777 break;
778 case MUX_FWD_REMOTE:
779 for (i = 0; i < options.num_remote_forwards; i++) {
780 if (!compare_forward(&fwd, options.remote_forwards + i))
781 continue;
782 if (fwd.listen_port != 0)
783 goto exists;
784 debug2_f("found allocated port");
785 if ((r = sshbuf_put_u32(reply,
786 MUX_S_REMOTE_PORT)) != 0 ||
787 (r = sshbuf_put_u32(reply, rid)) != 0 ||
788 (r = sshbuf_put_u32(reply,
789 options.remote_forwards[i].allocated_port)) != 0)
790 fatal_fr(r, "reply FWD_REMOTE");
791 goto out;
792 }
793 break;
794 }
795
796 if (options.control_master == SSHCTL_MASTER_ASK ||
797 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
798 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
799 debug2_f("forwarding refused by user");
800 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
801 "Permission denied");
802 goto out;
803 }
804 }
805
806 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
807 if (!channel_setup_local_fwd_listener(ssh, &fwd,
808 &options.fwd_opts)) {
809 fail:
810 logit_f("requested %s failed", fwd_desc);
811 reply_error(reply, MUX_S_FAILURE, rid,
812 "Port forwarding failed");
813 goto out;
814 }
815 add_local_forward(&options, &fwd);
816 freefwd = 0;
817 } else {
818 struct mux_channel_confirm_ctx *fctx;
819
820 fwd.handle = channel_request_remote_forwarding(ssh, &fwd);
821 if (fwd.handle < 0)
822 goto fail;
823 add_remote_forward(&options, &fwd);
824 fctx = xcalloc(1, sizeof(*fctx));
825 fctx->cid = c->self;
826 fctx->rid = rid;
827 fctx->fid = options.num_remote_forwards - 1;
828 client_register_global_confirm(mux_confirm_remote_forward,
829 fctx);
830 freefwd = 0;
831 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
832 /* delayed reply in mux_confirm_remote_forward */
833 goto out;
834 }
835 reply_ok(reply, rid);
836 out:
837 free(fwd_desc);
838 if (freefwd) {
839 free(fwd.listen_host);
840 free(fwd.listen_path);
841 free(fwd.connect_host);
842 free(fwd.connect_path);
843 }
844 return ret;
845 }
846
847 static int
mux_master_process_close_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)848 mux_master_process_close_fwd(struct ssh *ssh, u_int rid,
849 Channel *c, struct sshbuf *m, struct sshbuf *reply)
850 {
851 struct Forward fwd, *found_fwd;
852 char *fwd_desc = NULL;
853 const char *error_reason = NULL;
854 char *listen_addr = NULL, *connect_addr = NULL;
855 u_int ftype;
856 int r, i, ret = 0;
857 u_int lport, cport;
858
859 memset(&fwd, 0, sizeof(fwd));
860
861 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
862 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
863 (r = sshbuf_get_u32(m, &lport)) != 0 ||
864 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
865 (r = sshbuf_get_u32(m, &cport)) != 0 ||
866 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
867 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
868 error_f("malformed message");
869 ret = -1;
870 goto out;
871 }
872
873 if (*listen_addr == '\0') {
874 free(listen_addr);
875 listen_addr = NULL;
876 }
877 if (*connect_addr == '\0') {
878 free(connect_addr);
879 connect_addr = NULL;
880 }
881
882 memset(&fwd, 0, sizeof(fwd));
883 fwd.listen_port = lport;
884 if (fwd.listen_port == PORT_STREAMLOCAL)
885 fwd.listen_path = listen_addr;
886 else
887 fwd.listen_host = listen_addr;
888 fwd.connect_port = cport;
889 if (fwd.connect_port == PORT_STREAMLOCAL)
890 fwd.connect_path = connect_addr;
891 else
892 fwd.connect_host = connect_addr;
893
894 debug2_f("channel %d: request cancel %s", c->self,
895 (fwd_desc = format_forward(ftype, &fwd)));
896
897 /* make sure this has been requested */
898 found_fwd = NULL;
899 switch (ftype) {
900 case MUX_FWD_LOCAL:
901 case MUX_FWD_DYNAMIC:
902 for (i = 0; i < options.num_local_forwards; i++) {
903 if (compare_forward(&fwd,
904 options.local_forwards + i)) {
905 found_fwd = options.local_forwards + i;
906 break;
907 }
908 }
909 break;
910 case MUX_FWD_REMOTE:
911 for (i = 0; i < options.num_remote_forwards; i++) {
912 if (compare_forward(&fwd,
913 options.remote_forwards + i)) {
914 found_fwd = options.remote_forwards + i;
915 break;
916 }
917 }
918 break;
919 }
920
921 if (found_fwd == NULL)
922 error_reason = "port not forwarded";
923 else if (ftype == MUX_FWD_REMOTE) {
924 /*
925 * This shouldn't fail unless we confused the host/port
926 * between options.remote_forwards and permitted_opens.
927 * However, for dynamic allocated listen ports we need
928 * to use the actual listen port.
929 */
930 if (channel_request_rforward_cancel(ssh, found_fwd) == -1)
931 error_reason = "port not in permitted opens";
932 } else { /* local and dynamic forwards */
933 /* Ditto */
934 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port,
935 &options.fwd_opts) == -1)
936 error_reason = "port not found";
937 }
938
939 if (error_reason != NULL)
940 reply_error(reply, MUX_S_FAILURE, rid, error_reason);
941 else {
942 reply_ok(reply, rid);
943 free(found_fwd->listen_host);
944 free(found_fwd->listen_path);
945 free(found_fwd->connect_host);
946 free(found_fwd->connect_path);
947 found_fwd->listen_host = found_fwd->connect_host = NULL;
948 found_fwd->listen_path = found_fwd->connect_path = NULL;
949 found_fwd->listen_port = found_fwd->connect_port = 0;
950 }
951 out:
952 free(fwd_desc);
953 free(listen_addr);
954 free(connect_addr);
955
956 return ret;
957 }
958
959 static int
mux_master_process_stdio_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)960 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid,
961 Channel *c, struct sshbuf *m, struct sshbuf *reply)
962 {
963 Channel *nc;
964 char *chost = NULL;
965 u_int _cport, i, j;
966 int ok = 0, cport, r, new_fd[2];
967 struct mux_stdio_confirm_ctx *cctx;
968
969 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
970 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
971 (r = sshbuf_get_u32(m, &_cport)) != 0) {
972 free(chost);
973 error_f("malformed message");
974 return -1;
975 }
976 if (_cport == (u_int)PORT_STREAMLOCAL)
977 cport = PORT_STREAMLOCAL;
978 else if (_cport <= INT_MAX)
979 cport = (int)_cport;
980 else {
981 free(chost);
982 error_f("invalid port 0x%x", _cport);
983 return -1;
984 }
985
986 debug2_f("channel %d: stdio fwd to %s:%d", c->self, chost, cport);
987
988 /* Gather fds from client */
989 for(i = 0; i < 2; i++) {
990 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
991 error_f("failed to receive fd %d from client", i);
992 for (j = 0; j < i; j++)
993 close(new_fd[j]);
994 free(chost);
995
996 /* prepare reply */
997 reply_error(reply, MUX_S_FAILURE, rid,
998 "did not receive file descriptors");
999 return -1;
1000 }
1001 }
1002
1003 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]);
1004
1005 /* XXX support multiple child sessions in future */
1006 if (c->have_remote_id) {
1007 debug2_f("session already open");
1008 reply_error(reply, MUX_S_FAILURE, rid,
1009 "Multiple sessions not supported");
1010 cleanup:
1011 close(new_fd[0]);
1012 close(new_fd[1]);
1013 free(chost);
1014 return 0;
1015 }
1016
1017 if (options.control_master == SSHCTL_MASTER_ASK ||
1018 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1019 if (cport == PORT_STREAMLOCAL) {
1020 ok = ask_permission("Allow forward to path %s", chost);
1021 } else {
1022 ok = ask_permission("Allow forward to [%s]:%d? ",
1023 chost, cport);
1024 }
1025 if (!ok) {
1026 debug2_f("stdio fwd refused by user");
1027 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1028 "Permission denied");
1029 goto cleanup;
1030 }
1031 }
1032
1033 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1],
1034 CHANNEL_NONBLOCK_STDIO);
1035 free(chost);
1036
1037 nc->ctl_chan = c->self; /* link session -> control channel */
1038 c->remote_id = nc->self; /* link control -> session channel */
1039 c->have_remote_id = 1;
1040
1041 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan);
1042
1043 channel_register_cleanup(ssh, nc->self,
1044 mux_master_session_cleanup_cb, 1);
1045
1046 cctx = xcalloc(1, sizeof(*cctx));
1047 cctx->rid = rid;
1048 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx);
1049 c->mux_pause = 1; /* stop handling messages until open_confirm done */
1050
1051 /* reply is deferred, sent by mux_session_confirm */
1052 return 0;
1053 }
1054
1055 /* Callback on open confirmation in mux master for a mux stdio fwd session. */
1056 static void
mux_stdio_confirm(struct ssh * ssh,int id,int success,void * arg)1057 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1058 {
1059 struct mux_stdio_confirm_ctx *cctx = arg;
1060 Channel *c, *cc;
1061 struct sshbuf *reply;
1062 int r;
1063
1064 if (cctx == NULL)
1065 fatal_f("cctx == NULL");
1066 if ((c = channel_by_id(ssh, id)) == NULL)
1067 fatal_f("no channel for id %d", id);
1068 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1069 fatal_f("channel %d lacks control channel %d",
1070 id, c->ctl_chan);
1071 if ((reply = sshbuf_new()) == NULL)
1072 fatal_f("sshbuf_new");
1073
1074 if (!success) {
1075 debug3_f("sending failure reply");
1076 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1077 "Session open refused by peer");
1078 /* prepare reply */
1079 goto done;
1080 }
1081
1082 debug3_f("sending success reply");
1083 /* prepare reply */
1084 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1085 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1086 (r = sshbuf_put_u32(reply, c->self)) != 0)
1087 fatal_fr(r, "reply");
1088
1089 done:
1090 /* Send reply */
1091 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1092 fatal_fr(r, "enqueue");
1093 sshbuf_free(reply);
1094
1095 if (cc->mux_pause <= 0)
1096 fatal_f("mux_pause %d", cc->mux_pause);
1097 cc->mux_pause = 0; /* start processing messages again */
1098 c->open_confirm_ctx = NULL;
1099 free(cctx);
1100 }
1101
1102 static int
mux_master_process_stop_listening(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1103 mux_master_process_stop_listening(struct ssh *ssh, u_int rid,
1104 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1105 {
1106 debug_f("channel %d: stop listening", c->self);
1107
1108 if (options.control_master == SSHCTL_MASTER_ASK ||
1109 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1110 if (!ask_permission("Disable further multiplexing on shared "
1111 "connection to %s? ", host)) {
1112 debug2_f("stop listen refused by user");
1113 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1114 "Permission denied");
1115 return 0;
1116 }
1117 }
1118
1119 if (mux_listener_channel != NULL) {
1120 channel_free(ssh, mux_listener_channel);
1121 client_stop_mux();
1122 free(options.control_path);
1123 options.control_path = NULL;
1124 mux_listener_channel = NULL;
1125 muxserver_sock = -1;
1126 }
1127
1128 reply_ok(reply, rid);
1129 return 0;
1130 }
1131
1132 static int
mux_master_process_proxy(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1133 mux_master_process_proxy(struct ssh *ssh, u_int rid,
1134 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1135 {
1136 int r;
1137
1138 debug_f("channel %d: proxy request", c->self);
1139
1140 c->mux_rcb = channel_proxy_downstream;
1141 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 ||
1142 (r = sshbuf_put_u32(reply, rid)) != 0)
1143 fatal_fr(r, "reply");
1144
1145 return 0;
1146 }
1147
1148 /* Channel callbacks fired on read/write from mux client fd */
1149 static int
mux_master_read_cb(struct ssh * ssh,Channel * c)1150 mux_master_read_cb(struct ssh *ssh, Channel *c)
1151 {
1152 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
1153 struct sshbuf *in = NULL, *out = NULL;
1154 u_int type, rid, i;
1155 int r, ret = -1;
1156
1157 if ((out = sshbuf_new()) == NULL)
1158 fatal_f("sshbuf_new");
1159
1160 /* Setup ctx and */
1161 if (c->mux_ctx == NULL) {
1162 state = xcalloc(1, sizeof(*state));
1163 c->mux_ctx = state;
1164 channel_register_cleanup(ssh, c->self,
1165 mux_master_control_cleanup_cb, 0);
1166
1167 /* Send hello */
1168 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 ||
1169 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0)
1170 fatal_fr(r, "reply");
1171 /* no extensions */
1172 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
1173 fatal_fr(r, "enqueue");
1174 debug3_f("channel %d: hello sent", c->self);
1175 ret = 0;
1176 goto out;
1177 }
1178
1179 /* Channel code ensures that we receive whole packets */
1180 if ((r = sshbuf_froms(c->input, &in)) != 0) {
1181 malf:
1182 error_f("malformed message");
1183 goto out;
1184 }
1185
1186 if ((r = sshbuf_get_u32(in, &type)) != 0)
1187 goto malf;
1188 debug3_f("channel %d packet type 0x%08x len %zu", c->self,
1189 type, sshbuf_len(in));
1190
1191 if (type == MUX_MSG_HELLO)
1192 rid = 0;
1193 else {
1194 if (!state->hello_rcvd) {
1195 error_f("expected MUX_MSG_HELLO(0x%08x), "
1196 "received 0x%08x", MUX_MSG_HELLO, type);
1197 goto out;
1198 }
1199 if ((r = sshbuf_get_u32(in, &rid)) != 0)
1200 goto malf;
1201 }
1202
1203 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
1204 if (type == mux_master_handlers[i].type) {
1205 ret = mux_master_handlers[i].handler(ssh, rid,
1206 c, in, out);
1207 break;
1208 }
1209 }
1210 if (mux_master_handlers[i].handler == NULL) {
1211 error_f("unsupported mux message 0x%08x", type);
1212 reply_error(out, MUX_S_FAILURE, rid, "unsupported request");
1213 ret = 0;
1214 }
1215 /* Enqueue reply packet */
1216 if (sshbuf_len(out) != 0 &&
1217 (r = sshbuf_put_stringb(c->output, out)) != 0)
1218 fatal_fr(r, "enqueue");
1219 out:
1220 sshbuf_free(in);
1221 sshbuf_free(out);
1222 return ret;
1223 }
1224
1225 void
mux_exit_message(struct ssh * ssh,Channel * c,int exitval)1226 mux_exit_message(struct ssh *ssh, Channel *c, int exitval)
1227 {
1228 struct sshbuf *m;
1229 Channel *mux_chan;
1230 int r;
1231
1232 debug3_f("channel %d: exit message, exitval %d", c->self, exitval);
1233
1234 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1235 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan);
1236
1237 /* Append exit message packet to control socket output queue */
1238 if ((m = sshbuf_new()) == NULL)
1239 fatal_f("sshbuf_new");
1240 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 ||
1241 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1242 (r = sshbuf_put_u32(m, exitval)) != 0 ||
1243 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1244 fatal_fr(r, "reply");
1245 sshbuf_free(m);
1246 }
1247
1248 void
mux_tty_alloc_failed(struct ssh * ssh,Channel * c)1249 mux_tty_alloc_failed(struct ssh *ssh, Channel *c)
1250 {
1251 struct sshbuf *m;
1252 Channel *mux_chan;
1253 int r;
1254
1255 debug3_f("channel %d: TTY alloc failed", c->self);
1256
1257 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1258 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan);
1259
1260 /* Append exit message packet to control socket output queue */
1261 if ((m = sshbuf_new()) == NULL)
1262 fatal_f("sshbuf_new");
1263 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 ||
1264 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1265 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1266 fatal_fr(r, "reply");
1267 sshbuf_free(m);
1268 }
1269
1270 /* Prepare a mux master to listen on a Unix domain socket. */
1271 void
muxserver_listen(struct ssh * ssh)1272 muxserver_listen(struct ssh *ssh)
1273 {
1274 mode_t old_umask;
1275 char *orig_control_path = options.control_path;
1276 char rbuf[16+1];
1277 u_int i, r;
1278 int oerrno;
1279
1280 if (options.control_path == NULL ||
1281 options.control_master == SSHCTL_MASTER_NO)
1282 return;
1283
1284 debug("setting up multiplex master socket");
1285
1286 /*
1287 * Use a temporary path before listen so we can pseudo-atomically
1288 * establish the listening socket in its final location to avoid
1289 * other processes racing in between bind() and listen() and hitting
1290 * an unready socket.
1291 */
1292 for (i = 0; i < sizeof(rbuf) - 1; i++) {
1293 r = arc4random_uniform(26+26+10);
1294 rbuf[i] = (r < 26) ? 'a' + r :
1295 (r < 26*2) ? 'A' + r - 26 :
1296 '0' + r - 26 - 26;
1297 }
1298 rbuf[sizeof(rbuf) - 1] = '\0';
1299 options.control_path = NULL;
1300 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
1301 debug3_f("temporary control path %s", options.control_path);
1302
1303 old_umask = umask(0177);
1304 muxserver_sock = unix_listener(options.control_path, 64, 0);
1305 oerrno = errno;
1306 umask(old_umask);
1307 if (muxserver_sock < 0) {
1308 if (oerrno == EINVAL || oerrno == EADDRINUSE) {
1309 error("ControlSocket %s already exists, "
1310 "disabling multiplexing", options.control_path);
1311 disable_mux_master:
1312 if (muxserver_sock != -1) {
1313 close(muxserver_sock);
1314 muxserver_sock = -1;
1315 }
1316 free(orig_control_path);
1317 free(options.control_path);
1318 options.control_path = NULL;
1319 options.control_master = SSHCTL_MASTER_NO;
1320 return;
1321 } else {
1322 /* unix_listener() logs the error */
1323 cleanup_exit(255);
1324 }
1325 }
1326
1327 /* Now atomically "move" the mux socket into position */
1328 if (link(options.control_path, orig_control_path) != 0) {
1329 if (errno != EEXIST) {
1330 fatal_f("link mux listener %s => %s: %s",
1331 options.control_path, orig_control_path,
1332 strerror(errno));
1333 }
1334 error("ControlSocket %s already exists, disabling multiplexing",
1335 orig_control_path);
1336 unlink(options.control_path);
1337 goto disable_mux_master;
1338 }
1339 unlink(options.control_path);
1340 free(options.control_path);
1341 options.control_path = orig_control_path;
1342
1343 set_nonblock(muxserver_sock);
1344
1345 mux_listener_channel = channel_new(ssh, "mux listener",
1346 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
1347 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1348 0, options.control_path, 1);
1349 mux_listener_channel->mux_rcb = mux_master_read_cb;
1350 debug3_f("mux listener channel %d fd %d",
1351 mux_listener_channel->self, mux_listener_channel->sock);
1352 }
1353
1354 /* Callback on open confirmation in mux master for a mux client session. */
1355 static void
mux_session_confirm(struct ssh * ssh,int id,int success,void * arg)1356 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg)
1357 {
1358 struct mux_session_confirm_ctx *cctx = arg;
1359 const char *display;
1360 Channel *c, *cc;
1361 int i, r;
1362 struct sshbuf *reply;
1363
1364 if (cctx == NULL)
1365 fatal_f("cctx == NULL");
1366 if ((c = channel_by_id(ssh, id)) == NULL)
1367 fatal_f("no channel for id %d", id);
1368 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1369 fatal_f("channel %d lacks control channel %d",
1370 id, c->ctl_chan);
1371 if ((reply = sshbuf_new()) == NULL)
1372 fatal_f("sshbuf_new");
1373
1374 if (!success) {
1375 debug3_f("sending failure reply");
1376 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1377 "Session open refused by peer");
1378 goto done;
1379 }
1380
1381 display = getenv("DISPLAY");
1382 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1383 char *proto, *data;
1384
1385 /* Get reasonable local authentication information. */
1386 if (client_x11_get_proto(ssh, display, options.xauth_location,
1387 options.forward_x11_trusted, options.forward_x11_timeout,
1388 &proto, &data) == 0) {
1389 /* Request forwarding with authentication spoofing. */
1390 debug("Requesting X11 forwarding with authentication "
1391 "spoofing.");
1392 x11_request_forwarding_with_spoofing(ssh, id,
1393 display, proto, data, 1);
1394 /* XXX exit_on_forward_failure */
1395 client_expect_confirm(ssh, id, "X11 forwarding",
1396 CONFIRM_WARN);
1397 }
1398 }
1399
1400 if (cctx->want_agent_fwd && options.forward_agent) {
1401 debug("Requesting authentication agent forwarding.");
1402 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
1403 if ((r = sshpkt_send(ssh)) != 0)
1404 fatal_fr(r, "send");
1405 }
1406
1407 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys,
1408 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env);
1409
1410 debug3_f("sending success reply");
1411 /* prepare reply */
1412 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1413 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1414 (r = sshbuf_put_u32(reply, c->self)) != 0)
1415 fatal_fr(r, "reply");
1416
1417 done:
1418 /* Send reply */
1419 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1420 fatal_fr(r, "enqueue");
1421 sshbuf_free(reply);
1422
1423 if (cc->mux_pause <= 0)
1424 fatal_f("mux_pause %d", cc->mux_pause);
1425 cc->mux_pause = 0; /* start processing messages again */
1426 c->open_confirm_ctx = NULL;
1427 sshbuf_free(cctx->cmd);
1428 free(cctx->term);
1429 if (cctx->env != NULL) {
1430 for (i = 0; cctx->env[i] != NULL; i++)
1431 free(cctx->env[i]);
1432 free(cctx->env);
1433 }
1434 free(cctx);
1435 }
1436
1437 /* ** Multiplexing client support */
1438
1439 /* Exit signal handler */
1440 static void
control_client_sighandler(int signo)1441 control_client_sighandler(int signo)
1442 {
1443 muxclient_terminate = signo;
1444 }
1445
1446 /*
1447 * Relay signal handler - used to pass some signals from mux client to
1448 * mux master.
1449 */
1450 static void
control_client_sigrelay(int signo)1451 control_client_sigrelay(int signo)
1452 {
1453 int save_errno = errno;
1454
1455 if (muxserver_pid > 1)
1456 kill(muxserver_pid, signo);
1457
1458 errno = save_errno;
1459 }
1460
1461 static int
mux_client_read(int fd,struct sshbuf * b,size_t need,int timeout_ms)1462 mux_client_read(int fd, struct sshbuf *b, size_t need, int timeout_ms)
1463 {
1464 size_t have;
1465 ssize_t len;
1466 u_char *p;
1467 int r;
1468
1469 if ((r = sshbuf_reserve(b, need, &p)) != 0)
1470 fatal_fr(r, "reserve");
1471 for (have = 0; have < need; ) {
1472 if (muxclient_terminate) {
1473 errno = EINTR;
1474 return -1;
1475 }
1476 len = read(fd, p + have, need - have);
1477 if (len == -1) {
1478 switch (errno) {
1479 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1480 case EWOULDBLOCK:
1481 #endif
1482 case EAGAIN:
1483 if (waitrfd(fd, &timeout_ms,
1484 &muxclient_terminate) == -1 &&
1485 errno != EINTR)
1486 return -1; /* timeout */
1487 /* FALLTHROUGH */
1488 case EINTR:
1489 continue;
1490 default:
1491 return -1;
1492 }
1493 }
1494 if (len == 0) {
1495 errno = EPIPE;
1496 return -1;
1497 }
1498 have += (size_t)len;
1499 }
1500 return 0;
1501 }
1502
1503 static int
mux_client_write_packet(int fd,struct sshbuf * m)1504 mux_client_write_packet(int fd, struct sshbuf *m)
1505 {
1506 struct sshbuf *queue;
1507 u_int have, need;
1508 int r, oerrno, len;
1509 const u_char *ptr;
1510 struct pollfd pfd;
1511
1512 pfd.fd = fd;
1513 pfd.events = POLLOUT;
1514 if ((queue = sshbuf_new()) == NULL)
1515 fatal_f("sshbuf_new");
1516 if ((r = sshbuf_put_stringb(queue, m)) != 0)
1517 fatal_fr(r, "enqueue");
1518
1519 need = sshbuf_len(queue);
1520 ptr = sshbuf_ptr(queue);
1521
1522 for (have = 0; have < need; ) {
1523 if (muxclient_terminate) {
1524 sshbuf_free(queue);
1525 errno = EINTR;
1526 return -1;
1527 }
1528 len = write(fd, ptr + have, need - have);
1529 if (len == -1) {
1530 switch (errno) {
1531 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1532 case EWOULDBLOCK:
1533 #endif
1534 case EAGAIN:
1535 (void)poll(&pfd, 1, -1);
1536 /* FALLTHROUGH */
1537 case EINTR:
1538 continue;
1539 default:
1540 oerrno = errno;
1541 sshbuf_free(queue);
1542 errno = oerrno;
1543 return -1;
1544 }
1545 }
1546 if (len == 0) {
1547 sshbuf_free(queue);
1548 errno = EPIPE;
1549 return -1;
1550 }
1551 have += (u_int)len;
1552 }
1553 sshbuf_free(queue);
1554 return 0;
1555 }
1556
1557 static int
mux_client_read_packet_timeout(int fd,struct sshbuf * m,int timeout_ms)1558 mux_client_read_packet_timeout(int fd, struct sshbuf *m, int timeout_ms)
1559 {
1560 struct sshbuf *queue;
1561 size_t need, have;
1562 const u_char *ptr;
1563 int r, oerrno;
1564
1565 if ((queue = sshbuf_new()) == NULL)
1566 fatal_f("sshbuf_new");
1567 if (mux_client_read(fd, queue, 4, timeout_ms) != 0) {
1568 if ((oerrno = errno) == EPIPE)
1569 debug3_f("read header failed: %s",
1570 strerror(errno));
1571 sshbuf_free(queue);
1572 errno = oerrno;
1573 return -1;
1574 }
1575 need = PEEK_U32(sshbuf_ptr(queue));
1576 if (mux_client_read(fd, queue, need, timeout_ms) != 0) {
1577 oerrno = errno;
1578 debug3_f("read body failed: %s", strerror(errno));
1579 sshbuf_free(queue);
1580 errno = oerrno;
1581 return -1;
1582 }
1583 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 ||
1584 (r = sshbuf_put(m, ptr, have)) != 0)
1585 fatal_fr(r, "dequeue");
1586 sshbuf_free(queue);
1587 return 0;
1588 }
1589
1590 static int
mux_client_read_packet(int fd,struct sshbuf * m)1591 mux_client_read_packet(int fd, struct sshbuf *m)
1592 {
1593 return mux_client_read_packet_timeout(fd, m, -1);
1594 }
1595
1596 static int
mux_client_hello_exchange(int fd,int timeout_ms)1597 mux_client_hello_exchange(int fd, int timeout_ms)
1598 {
1599 struct sshbuf *m;
1600 u_int type, ver;
1601 int r, ret = -1;
1602
1603 if ((m = sshbuf_new()) == NULL)
1604 fatal_f("sshbuf_new");
1605 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 ||
1606 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0)
1607 fatal_fr(r, "assemble hello");
1608 /* no extensions */
1609
1610 if (mux_client_write_packet(fd, m) != 0) {
1611 debug_f("write packet: %s", strerror(errno));
1612 goto out;
1613 }
1614
1615 sshbuf_reset(m);
1616
1617 /* Read their HELLO */
1618 if (mux_client_read_packet_timeout(fd, m, timeout_ms) != 0) {
1619 debug_f("read packet failed");
1620 goto out;
1621 }
1622
1623 if ((r = sshbuf_get_u32(m, &type)) != 0)
1624 fatal_fr(r, "parse type");
1625 if (type != MUX_MSG_HELLO) {
1626 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type);
1627 goto out;
1628 }
1629 if ((r = sshbuf_get_u32(m, &ver)) != 0)
1630 fatal_fr(r, "parse version");
1631 if (ver != SSHMUX_VER) {
1632 error("Unsupported multiplexing protocol version %d "
1633 "(expected %d)", ver, SSHMUX_VER);
1634 goto out;
1635 }
1636 debug2_f("master version %u", ver);
1637 /* No extensions are presently defined */
1638 while (sshbuf_len(m) > 0) {
1639 char *name = NULL;
1640
1641 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
1642 (r = sshbuf_skip_string(m)) != 0) { /* value */
1643 error_fr(r, "parse extension");
1644 goto out;
1645 }
1646 debug2("Unrecognised master extension \"%s\"", name);
1647 free(name);
1648 }
1649 /* success */
1650 ret = 0;
1651 out:
1652 sshbuf_free(m);
1653 return ret;
1654 }
1655
1656 static u_int
mux_client_request_alive(int fd)1657 mux_client_request_alive(int fd)
1658 {
1659 struct sshbuf *m;
1660 char *e;
1661 u_int pid, type, rid;
1662 int r;
1663
1664 debug3_f("entering");
1665
1666 if ((m = sshbuf_new()) == NULL)
1667 fatal_f("sshbuf_new");
1668 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 ||
1669 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1670 fatal_fr(r, "assemble");
1671
1672 if (mux_client_write_packet(fd, m) != 0)
1673 fatal_f("write packet: %s", strerror(errno));
1674
1675 sshbuf_reset(m);
1676
1677 /* Read their reply */
1678 if (mux_client_read_packet(fd, m) != 0) {
1679 sshbuf_free(m);
1680 return 0;
1681 }
1682
1683 if ((r = sshbuf_get_u32(m, &type)) != 0)
1684 fatal_fr(r, "parse type");
1685 if (type != MUX_S_ALIVE) {
1686 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1687 fatal_fr(r, "parse error message");
1688 fatal_f("master returned error: %s", e);
1689 }
1690
1691 if ((r = sshbuf_get_u32(m, &rid)) != 0)
1692 fatal_fr(r, "parse remote ID");
1693 if (rid != muxclient_request_id)
1694 fatal_f("out of sequence reply: my id %u theirs %u",
1695 muxclient_request_id, rid);
1696 if ((r = sshbuf_get_u32(m, &pid)) != 0)
1697 fatal_fr(r, "parse PID");
1698 sshbuf_free(m);
1699
1700 debug3_f("done pid = %u", pid);
1701
1702 muxclient_request_id++;
1703
1704 return pid;
1705 }
1706
1707 static void
mux_client_request_terminate(int fd)1708 mux_client_request_terminate(int fd)
1709 {
1710 struct sshbuf *m;
1711 char *e;
1712 u_int type, rid;
1713 int r;
1714
1715 debug3_f("entering");
1716
1717 if ((m = sshbuf_new()) == NULL)
1718 fatal_f("sshbuf_new");
1719 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 ||
1720 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1721 fatal_fr(r, "request");
1722
1723 if (mux_client_write_packet(fd, m) != 0)
1724 fatal_f("write packet: %s", strerror(errno));
1725
1726 sshbuf_reset(m);
1727
1728 /* Read their reply */
1729 if (mux_client_read_packet(fd, m) != 0) {
1730 /* Remote end exited already */
1731 if (errno == EPIPE) {
1732 sshbuf_free(m);
1733 return;
1734 }
1735 fatal_f("read from master failed: %s", strerror(errno));
1736 }
1737
1738 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1739 (r = sshbuf_get_u32(m, &rid)) != 0)
1740 fatal_fr(r, "parse");
1741 if (rid != muxclient_request_id)
1742 fatal_f("out of sequence reply: my id %u theirs %u",
1743 muxclient_request_id, rid);
1744 switch (type) {
1745 case MUX_S_OK:
1746 break;
1747 case MUX_S_PERMISSION_DENIED:
1748 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1749 fatal_fr(r, "parse error message");
1750 fatal("Master refused termination request: %s", e);
1751 case MUX_S_FAILURE:
1752 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1753 fatal_fr(r, "parse error message");
1754 fatal_f("termination request failed: %s", e);
1755 default:
1756 fatal_f("unexpected response from master 0x%08x", type);
1757 }
1758 sshbuf_free(m);
1759 muxclient_request_id++;
1760 }
1761
1762 static int
mux_client_forward(int fd,int cancel_flag,u_int ftype,struct Forward * fwd)1763 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd)
1764 {
1765 struct sshbuf *m;
1766 char *e, *fwd_desc;
1767 const char *lhost, *chost;
1768 u_int type, rid;
1769 int r;
1770
1771 fwd_desc = format_forward(ftype, fwd);
1772 debug("Requesting %s %s",
1773 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc);
1774 free(fwd_desc);
1775
1776 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD;
1777 if (fwd->listen_path != NULL)
1778 lhost = fwd->listen_path;
1779 else if (fwd->listen_host == NULL)
1780 lhost = "";
1781 else if (*fwd->listen_host == '\0')
1782 lhost = "*";
1783 else
1784 lhost = fwd->listen_host;
1785
1786 if (fwd->connect_path != NULL)
1787 chost = fwd->connect_path;
1788 else if (fwd->connect_host == NULL)
1789 chost = "";
1790 else
1791 chost = fwd->connect_host;
1792
1793 if ((m = sshbuf_new()) == NULL)
1794 fatal_f("sshbuf_new");
1795 if ((r = sshbuf_put_u32(m, type)) != 0 ||
1796 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1797 (r = sshbuf_put_u32(m, ftype)) != 0 ||
1798 (r = sshbuf_put_cstring(m, lhost)) != 0 ||
1799 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 ||
1800 (r = sshbuf_put_cstring(m, chost)) != 0 ||
1801 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0)
1802 fatal_fr(r, "request");
1803
1804 if (mux_client_write_packet(fd, m) != 0)
1805 fatal_f("write packet: %s", strerror(errno));
1806
1807 sshbuf_reset(m);
1808
1809 /* Read their reply */
1810 if (mux_client_read_packet(fd, m) != 0) {
1811 sshbuf_free(m);
1812 return -1;
1813 }
1814
1815 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1816 (r = sshbuf_get_u32(m, &rid)) != 0)
1817 fatal_fr(r, "parse");
1818 if (rid != muxclient_request_id)
1819 fatal_f("out of sequence reply: my id %u theirs %u",
1820 muxclient_request_id, rid);
1821
1822 switch (type) {
1823 case MUX_S_OK:
1824 break;
1825 case MUX_S_REMOTE_PORT:
1826 if (cancel_flag)
1827 fatal_f("got MUX_S_REMOTE_PORT for cancel");
1828 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0)
1829 fatal_fr(r, "parse port");
1830 verbose("Allocated port %u for remote forward to %s:%d",
1831 fwd->allocated_port,
1832 fwd->connect_host ? fwd->connect_host : "",
1833 fwd->connect_port);
1834 if (muxclient_command == SSHMUX_COMMAND_FORWARD)
1835 fprintf(stdout, "%i\n", fwd->allocated_port);
1836 break;
1837 case MUX_S_PERMISSION_DENIED:
1838 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1839 fatal_fr(r, "parse error message");
1840 sshbuf_free(m);
1841 error("Master refused forwarding request: %s", e);
1842 return -1;
1843 case MUX_S_FAILURE:
1844 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1845 fatal_fr(r, "parse error message");
1846 sshbuf_free(m);
1847 error_f("forwarding request failed: %s", e);
1848 return -1;
1849 default:
1850 fatal_f("unexpected response from master 0x%08x", type);
1851 }
1852 sshbuf_free(m);
1853
1854 muxclient_request_id++;
1855 return 0;
1856 }
1857
1858 static int
mux_client_forwards(int fd,int cancel_flag)1859 mux_client_forwards(int fd, int cancel_flag)
1860 {
1861 int i, ret = 0;
1862
1863 debug3_f("%s forwardings: %d local, %d remote",
1864 cancel_flag ? "cancel" : "request",
1865 options.num_local_forwards, options.num_remote_forwards);
1866
1867 /* XXX ExitOnForwardingFailure */
1868 for (i = 0; i < options.num_local_forwards; i++) {
1869 if (mux_client_forward(fd, cancel_flag,
1870 options.local_forwards[i].connect_port == 0 ?
1871 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1872 options.local_forwards + i) != 0)
1873 ret = -1;
1874 }
1875 for (i = 0; i < options.num_remote_forwards; i++) {
1876 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE,
1877 options.remote_forwards + i) != 0)
1878 ret = -1;
1879 }
1880 return ret;
1881 }
1882
1883 static int
mux_client_request_session(int fd)1884 mux_client_request_session(int fd)
1885 {
1886 struct sshbuf *m;
1887 char *e;
1888 const char *term = NULL;
1889 u_int i, echar, rid, sid, esid, exitval, type, exitval_seen;
1890 extern char **environ;
1891 int r, rawmode = 0;
1892
1893 debug3_f("entering");
1894
1895 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1896 error_f("master alive request failed");
1897 return -1;
1898 }
1899
1900 ssh_signal(SIGPIPE, SIG_IGN);
1901
1902 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1)
1903 fatal_f("stdfd_devnull failed");
1904
1905 if ((term = lookup_env_in_list("TERM", options.setenv,
1906 options.num_setenv)) == NULL || *term == '\0')
1907 term = getenv("TERM");
1908
1909 echar = 0xffffffff;
1910 if (options.escape_char != SSH_ESCAPECHAR_NONE)
1911 echar = (u_int)options.escape_char;
1912
1913 if ((m = sshbuf_new()) == NULL)
1914 fatal_f("sshbuf_new");
1915 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 ||
1916 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1917 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
1918 (r = sshbuf_put_u32(m, tty_flag)) != 0 ||
1919 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 ||
1920 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 ||
1921 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 ||
1922 (r = sshbuf_put_u32(m, echar)) != 0 ||
1923 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 ||
1924 (r = sshbuf_put_stringb(m, command)) != 0)
1925 fatal_fr(r, "request");
1926
1927 /* Pass environment */
1928 if (options.num_send_env > 0 && environ != NULL) {
1929 for (i = 0; environ[i] != NULL; i++) {
1930 if (!env_permitted(environ[i]))
1931 continue;
1932 if ((r = sshbuf_put_cstring(m, environ[i])) != 0)
1933 fatal_fr(r, "request sendenv");
1934 }
1935 }
1936 for (i = 0; i < options.num_setenv; i++) {
1937 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0)
1938 fatal_fr(r, "request setenv");
1939 }
1940
1941 if (mux_client_write_packet(fd, m) != 0)
1942 fatal_f("write packet: %s", strerror(errno));
1943
1944 /* Send the stdio file descriptors */
1945 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1946 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1947 mm_send_fd(fd, STDERR_FILENO) == -1)
1948 fatal_f("send fds failed");
1949
1950 debug3_f("session request sent");
1951
1952 /* Read their reply */
1953 sshbuf_reset(m);
1954 if (mux_client_read_packet(fd, m) != 0) {
1955 error_f("read from master failed: %s", strerror(errno));
1956 sshbuf_free(m);
1957 return -1;
1958 }
1959
1960 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1961 (r = sshbuf_get_u32(m, &rid)) != 0)
1962 fatal_fr(r, "parse");
1963 if (rid != muxclient_request_id)
1964 fatal_f("out of sequence reply: my id %u theirs %u",
1965 muxclient_request_id, rid);
1966
1967 switch (type) {
1968 case MUX_S_SESSION_OPENED:
1969 if ((r = sshbuf_get_u32(m, &sid)) != 0)
1970 fatal_fr(r, "parse session ID");
1971 debug_f("master session id: %u", sid);
1972 break;
1973 case MUX_S_PERMISSION_DENIED:
1974 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1975 fatal_fr(r, "parse error message");
1976 error("Master refused session request: %s", e);
1977 sshbuf_free(m);
1978 return -1;
1979 case MUX_S_FAILURE:
1980 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1981 fatal_fr(r, "parse error message");
1982 error_f("session request failed: %s", e);
1983 sshbuf_free(m);
1984 return -1;
1985 default:
1986 sshbuf_free(m);
1987 error_f("unexpected response from master 0x%08x", type);
1988 return -1;
1989 }
1990 muxclient_request_id++;
1991
1992 if (pledge("stdio proc tty", NULL) == -1)
1993 fatal_f("pledge(): %s", strerror(errno));
1994 platform_pledge_mux();
1995
1996 ssh_signal(SIGHUP, control_client_sighandler);
1997 ssh_signal(SIGINT, control_client_sighandler);
1998 ssh_signal(SIGTERM, control_client_sighandler);
1999 ssh_signal(SIGWINCH, control_client_sigrelay);
2000
2001 if (options.fork_after_authentication)
2002 daemon(1, 1);
2003 else {
2004 rawmode = tty_flag;
2005 if (tty_flag) {
2006 enter_raw_mode(
2007 options.request_tty == REQUEST_TTY_FORCE);
2008 }
2009 }
2010
2011 /*
2012 * Stick around until the controlee closes the client_fd.
2013 * Before it does, it is expected to write an exit message.
2014 * This process must read the value and wait for the closure of
2015 * the client_fd; if this one closes early, the multiplex master will
2016 * terminate early too (possibly losing data).
2017 */
2018 for (exitval = 255, exitval_seen = 0;;) {
2019 sshbuf_reset(m);
2020 if (mux_client_read_packet(fd, m) != 0)
2021 break;
2022 if ((r = sshbuf_get_u32(m, &type)) != 0)
2023 fatal_fr(r, "parse type");
2024 switch (type) {
2025 case MUX_S_TTY_ALLOC_FAIL:
2026 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2027 fatal_fr(r, "parse session ID");
2028 if (esid != sid)
2029 fatal_f("tty alloc fail on unknown session: "
2030 "my id %u theirs %u", sid, esid);
2031 leave_raw_mode(options.request_tty ==
2032 REQUEST_TTY_FORCE);
2033 rawmode = 0;
2034 continue;
2035 case MUX_S_EXIT_MESSAGE:
2036 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2037 fatal_fr(r, "parse session ID");
2038 if (esid != sid)
2039 fatal_f("exit on unknown session: "
2040 "my id %u theirs %u", sid, esid);
2041 if (exitval_seen)
2042 fatal_f("exitval sent twice");
2043 if ((r = sshbuf_get_u32(m, &exitval)) != 0)
2044 fatal_fr(r, "parse exitval");
2045 exitval_seen = 1;
2046 continue;
2047 default:
2048 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2049 fatal_fr(r, "parse error message");
2050 fatal_f("master returned error: %s", e);
2051 }
2052 }
2053
2054 close(fd);
2055 if (rawmode)
2056 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2057
2058 if (muxclient_terminate) {
2059 debug2("Exiting on signal: %s", strsignal(muxclient_terminate));
2060 exitval = 255;
2061 } else if (!exitval_seen) {
2062 debug2("Control master terminated unexpectedly");
2063 exitval = 255;
2064 } else
2065 debug2("Received exit status from master %d", exitval);
2066
2067 if (tty_flag && options.log_level >= SYSLOG_LEVEL_INFO)
2068 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
2069
2070 exit(exitval);
2071 }
2072
2073 static int
mux_client_proxy(int fd)2074 mux_client_proxy(int fd)
2075 {
2076 struct sshbuf *m;
2077 char *e;
2078 u_int type, rid;
2079 int r;
2080
2081 if ((m = sshbuf_new()) == NULL)
2082 fatal_f("sshbuf_new");
2083 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 ||
2084 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2085 fatal_fr(r, "request");
2086 if (mux_client_write_packet(fd, m) != 0)
2087 fatal_f("write packet: %s", strerror(errno));
2088
2089 sshbuf_reset(m);
2090
2091 /* Read their reply */
2092 if (mux_client_read_packet(fd, m) != 0) {
2093 sshbuf_free(m);
2094 return 0;
2095 }
2096 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2097 (r = sshbuf_get_u32(m, &rid)) != 0)
2098 fatal_fr(r, "parse");
2099 if (rid != muxclient_request_id)
2100 fatal_f("out of sequence reply: my id %u theirs %u",
2101 muxclient_request_id, rid);
2102 if (type != MUX_S_PROXY) {
2103 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2104 fatal_fr(r, "parse error message");
2105 fatal_f("master returned error: %s", e);
2106 }
2107 sshbuf_free(m);
2108
2109 debug3_f("done");
2110 muxclient_request_id++;
2111 return 0;
2112 }
2113
2114 static int
mux_client_request_stdio_fwd(int fd)2115 mux_client_request_stdio_fwd(int fd)
2116 {
2117 struct sshbuf *m;
2118 char *e;
2119 u_int type, rid, sid;
2120 int r;
2121
2122 debug3_f("entering");
2123
2124 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
2125 error_f("master alive request failed");
2126 return -1;
2127 }
2128
2129 ssh_signal(SIGPIPE, SIG_IGN);
2130
2131 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1)
2132 fatal_f("stdfd_devnull failed");
2133
2134 if ((m = sshbuf_new()) == NULL)
2135 fatal_f("sshbuf_new");
2136 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 ||
2137 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
2138 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
2139 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 ||
2140 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0)
2141 fatal_fr(r, "request");
2142
2143 if (mux_client_write_packet(fd, m) != 0)
2144 fatal_f("write packet: %s", strerror(errno));
2145
2146 /* Send the stdio file descriptors */
2147 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
2148 mm_send_fd(fd, STDOUT_FILENO) == -1)
2149 fatal_f("send fds failed");
2150
2151 if (pledge("stdio proc tty", NULL) == -1)
2152 fatal_f("pledge(): %s", strerror(errno));
2153 platform_pledge_mux();
2154
2155 debug3_f("stdio forward request sent");
2156
2157 /* Read their reply */
2158 sshbuf_reset(m);
2159
2160 if (mux_client_read_packet(fd, m) != 0) {
2161 error_f("read from master failed: %s", strerror(errno));
2162 sshbuf_free(m);
2163 return -1;
2164 }
2165
2166 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2167 (r = sshbuf_get_u32(m, &rid)) != 0)
2168 fatal_fr(r, "parse");
2169 if (rid != muxclient_request_id)
2170 fatal_f("out of sequence reply: my id %u theirs %u",
2171 muxclient_request_id, rid);
2172 switch (type) {
2173 case MUX_S_SESSION_OPENED:
2174 if ((r = sshbuf_get_u32(m, &sid)) != 0)
2175 fatal_fr(r, "parse session ID");
2176 debug_f("master session id: %u", sid);
2177 break;
2178 case MUX_S_PERMISSION_DENIED:
2179 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2180 fatal_fr(r, "parse error message");
2181 sshbuf_free(m);
2182 fatal("Master refused stdio forwarding request: %s", e);
2183 case MUX_S_FAILURE:
2184 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2185 fatal_fr(r, "parse error message");
2186 sshbuf_free(m);
2187 fatal("Stdio forwarding request failed: %s", e);
2188 default:
2189 sshbuf_free(m);
2190 error_f("unexpected response from master 0x%08x", type);
2191 return -1;
2192 }
2193 muxclient_request_id++;
2194
2195 ssh_signal(SIGHUP, control_client_sighandler);
2196 ssh_signal(SIGINT, control_client_sighandler);
2197 ssh_signal(SIGTERM, control_client_sighandler);
2198 ssh_signal(SIGWINCH, control_client_sigrelay);
2199
2200 /*
2201 * Stick around until the controlee closes the client_fd.
2202 */
2203 sshbuf_reset(m);
2204 if (mux_client_read_packet(fd, m) != 0) {
2205 if (errno == EPIPE ||
2206 (errno == EINTR && muxclient_terminate != 0))
2207 return 0;
2208 fatal_f("mux_client_read_packet: %s", strerror(errno));
2209 }
2210 fatal_f("master returned unexpected message %u", type);
2211 }
2212
2213 static void
mux_client_request_stop_listening(int fd)2214 mux_client_request_stop_listening(int fd)
2215 {
2216 struct sshbuf *m;
2217 char *e;
2218 u_int type, rid;
2219 int r;
2220
2221 debug3_f("entering");
2222
2223 if ((m = sshbuf_new()) == NULL)
2224 fatal_f("sshbuf_new");
2225 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 ||
2226 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2227 fatal_fr(r, "request");
2228
2229 if (mux_client_write_packet(fd, m) != 0)
2230 fatal_f("write packet: %s", strerror(errno));
2231
2232 sshbuf_reset(m);
2233
2234 /* Read their reply */
2235 if (mux_client_read_packet(fd, m) != 0)
2236 fatal_f("read from master failed: %s", strerror(errno));
2237
2238 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2239 (r = sshbuf_get_u32(m, &rid)) != 0)
2240 fatal_fr(r, "parse");
2241 if (rid != muxclient_request_id)
2242 fatal_f("out of sequence reply: my id %u theirs %u",
2243 muxclient_request_id, rid);
2244
2245 switch (type) {
2246 case MUX_S_OK:
2247 break;
2248 case MUX_S_PERMISSION_DENIED:
2249 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2250 fatal_fr(r, "parse error message");
2251 fatal("Master refused stop listening request: %s", e);
2252 case MUX_S_FAILURE:
2253 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2254 fatal_fr(r, "parse error message");
2255 fatal_f("stop listening request failed: %s", e);
2256 default:
2257 fatal_f("unexpected response from master 0x%08x", type);
2258 }
2259 sshbuf_free(m);
2260 muxclient_request_id++;
2261 }
2262
2263 /* Multiplex client main loop. */
2264 int
muxclient(const char * path)2265 muxclient(const char *path)
2266 {
2267 struct sockaddr_un addr;
2268 int sock, timeout = options.connection_timeout, timeout_ms = -1;
2269 u_int pid;
2270
2271 if (muxclient_command == 0) {
2272 if (options.stdio_forward_host != NULL)
2273 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
2274 else
2275 muxclient_command = SSHMUX_COMMAND_OPEN;
2276 }
2277
2278 switch (options.control_master) {
2279 case SSHCTL_MASTER_AUTO:
2280 case SSHCTL_MASTER_AUTO_ASK:
2281 debug("auto-mux: Trying existing master at '%s'", path);
2282 /* FALLTHROUGH */
2283 case SSHCTL_MASTER_NO:
2284 break;
2285 default:
2286 return -1;
2287 }
2288
2289 memset(&addr, '\0', sizeof(addr));
2290 addr.sun_family = AF_UNIX;
2291
2292 if (strlcpy(addr.sun_path, path,
2293 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
2294 fatal("ControlPath too long ('%s' >= %u bytes)", path,
2295 (unsigned int)sizeof(addr.sun_path));
2296
2297 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
2298 fatal_f("socket(): %s", strerror(errno));
2299
2300 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
2301 switch (muxclient_command) {
2302 case SSHMUX_COMMAND_OPEN:
2303 case SSHMUX_COMMAND_STDIO_FWD:
2304 break;
2305 default:
2306 fatal("Control socket connect(%.100s): %s", path,
2307 strerror(errno));
2308 }
2309 if (errno == ECONNREFUSED &&
2310 options.control_master != SSHCTL_MASTER_NO) {
2311 debug("Stale control socket %.100s, unlinking", path);
2312 unlink(path);
2313 } else if (errno == ENOENT) {
2314 debug("Control socket \"%.100s\" does not exist", path);
2315 } else {
2316 error("Control socket connect(%.100s): %s", path,
2317 strerror(errno));
2318 }
2319 close(sock);
2320 return -1;
2321 }
2322 set_nonblock(sock);
2323
2324 /* Timeout on initial connection only. */
2325 if (timeout > 0 && timeout < INT_MAX / 1000)
2326 timeout_ms = timeout * 1000;
2327
2328 if (mux_client_hello_exchange(sock, timeout_ms) != 0) {
2329 error_f("master hello exchange failed");
2330 close(sock);
2331 return -1;
2332 }
2333
2334 switch (muxclient_command) {
2335 case SSHMUX_COMMAND_ALIVE_CHECK:
2336 if ((pid = mux_client_request_alive(sock)) == 0)
2337 fatal_f("master alive check failed");
2338 fprintf(stderr, "Master running (pid=%u)\r\n", pid);
2339 exit(0);
2340 case SSHMUX_COMMAND_TERMINATE:
2341 mux_client_request_terminate(sock);
2342 if (options.log_level != SYSLOG_LEVEL_QUIET)
2343 fprintf(stderr, "Exit request sent.\r\n");
2344 exit(0);
2345 case SSHMUX_COMMAND_FORWARD:
2346 if (mux_client_forwards(sock, 0) != 0)
2347 fatal_f("master forward request failed");
2348 exit(0);
2349 case SSHMUX_COMMAND_OPEN:
2350 if (mux_client_forwards(sock, 0) != 0) {
2351 error_f("master forward request failed");
2352 return -1;
2353 }
2354 mux_client_request_session(sock);
2355 return -1;
2356 case SSHMUX_COMMAND_STDIO_FWD:
2357 mux_client_request_stdio_fwd(sock);
2358 exit(0);
2359 case SSHMUX_COMMAND_STOP:
2360 mux_client_request_stop_listening(sock);
2361 if (options.log_level != SYSLOG_LEVEL_QUIET)
2362 fprintf(stderr, "Stop listening request sent.\r\n");
2363 exit(0);
2364 case SSHMUX_COMMAND_CANCEL_FWD:
2365 if (mux_client_forwards(sock, 1) != 0)
2366 error_f("master cancel forward request failed");
2367 exit(0);
2368 case SSHMUX_COMMAND_PROXY:
2369 mux_client_proxy(sock);
2370 return (sock);
2371 default:
2372 fatal("unrecognised muxclient_command %d", muxclient_command);
2373 }
2374 }
2375