1 /* $OpenBSD: mux.c,v 1.82 2020/04/30 17:12:20 markus 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 int stdin_null_flag;
75 extern char *host;
76 extern int subsystem_flag;
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 slave _session_ channel */
191 /* ARGSUSED */
192 static void
mux_master_session_cleanup_cb(struct ssh * ssh,int cid,void * unused)193 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused)
194 {
195 Channel *cc, *c = channel_by_id(ssh, cid);
196
197 debug3("%s: entering for channel %d", __func__, cid);
198 if (c == NULL)
199 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
200 if (c->ctl_chan != -1) {
201 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
202 fatal("%s: channel %d missing control channel %d",
203 __func__, c->self, c->ctl_chan);
204 c->ctl_chan = -1;
205 cc->remote_id = 0;
206 cc->have_remote_id = 0;
207 chan_rcvd_oclose(ssh, cc);
208 }
209 channel_cancel_cleanup(ssh, c->self);
210 }
211
212 /* Cleanup callback fired on closure of mux slave _control_ channel */
213 /* ARGSUSED */
214 static void
mux_master_control_cleanup_cb(struct ssh * ssh,int cid,void * unused)215 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused)
216 {
217 Channel *sc, *c = channel_by_id(ssh, cid);
218
219 debug3("%s: entering for channel %d", __func__, cid);
220 if (c == NULL)
221 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
222 if (c->have_remote_id) {
223 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL)
224 fatal("%s: channel %d missing session channel %u",
225 __func__, c->self, c->remote_id);
226 c->remote_id = 0;
227 c->have_remote_id = 0;
228 sc->ctl_chan = -1;
229 if (sc->type != SSH_CHANNEL_OPEN &&
230 sc->type != SSH_CHANNEL_OPENING) {
231 debug2("%s: channel %d: not open", __func__, sc->self);
232 chan_mark_dead(ssh, sc);
233 } else {
234 if (sc->istate == CHAN_INPUT_OPEN)
235 chan_read_failed(ssh, sc);
236 if (sc->ostate == CHAN_OUTPUT_OPEN)
237 chan_write_failed(ssh, sc);
238 }
239 }
240 channel_cancel_cleanup(ssh, c->self);
241 }
242
243 /* Check mux client environment variables before passing them to mux master. */
244 static int
env_permitted(char * env)245 env_permitted(char *env)
246 {
247 int i, ret;
248 char name[1024], *cp;
249
250 if ((cp = strchr(env, '=')) == NULL || cp == env)
251 return 0;
252 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
253 if (ret <= 0 || (size_t)ret >= sizeof(name)) {
254 error("%s: name '%.100s...' too long", __func__, env);
255 return 0;
256 }
257
258 for (i = 0; i < options.num_send_env; i++)
259 if (match_pattern(name, options.send_env[i]))
260 return 1;
261
262 return 0;
263 }
264
265 /* Mux master protocol message handlers */
266
267 static int
mux_master_process_hello(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)268 mux_master_process_hello(struct ssh *ssh, u_int rid,
269 Channel *c, struct sshbuf *m, struct sshbuf *reply)
270 {
271 u_int ver;
272 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
273 int r;
274
275 if (state == NULL)
276 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self);
277 if (state->hello_rcvd) {
278 error("%s: HELLO received twice", __func__);
279 return -1;
280 }
281 if ((r = sshbuf_get_u32(m, &ver)) != 0) {
282 error("%s: malformed message: %s", __func__, ssh_err(r));
283 return -1;
284 }
285 if (ver != SSHMUX_VER) {
286 error("%s: unsupported multiplexing protocol version %u "
287 "(expected %u)", __func__, ver, SSHMUX_VER);
288 return -1;
289 }
290 debug2("%s: channel %d slave version %u", __func__, c->self, ver);
291
292 /* No extensions are presently defined */
293 while (sshbuf_len(m) > 0) {
294 char *name = NULL;
295 size_t value_len = 0;
296
297 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
298 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) {
299 error("%s: malformed extension: %s",
300 __func__, ssh_err(r));
301 return -1;
302 }
303 debug2("%s: Unrecognised extension \"%s\" length %zu",
304 __func__, name, value_len);
305 free(name);
306 }
307 state->hello_rcvd = 1;
308 return 0;
309 }
310
311 /* Enqueue a "ok" response to the reply buffer */
312 static void
reply_ok(struct sshbuf * reply,u_int rid)313 reply_ok(struct sshbuf *reply, u_int rid)
314 {
315 int r;
316
317 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 ||
318 (r = sshbuf_put_u32(reply, rid)) != 0)
319 fatal("%s: reply: %s", __func__, ssh_err(r));
320 }
321
322 /* Enqueue an error response to the reply buffer */
323 static void
reply_error(struct sshbuf * reply,u_int type,u_int rid,const char * msg)324 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg)
325 {
326 int r;
327
328 if ((r = sshbuf_put_u32(reply, type)) != 0 ||
329 (r = sshbuf_put_u32(reply, rid)) != 0 ||
330 (r = sshbuf_put_cstring(reply, msg)) != 0)
331 fatal("%s: reply: %s", __func__, ssh_err(r));
332 }
333
334 static int
mux_master_process_new_session(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)335 mux_master_process_new_session(struct ssh *ssh, u_int rid,
336 Channel *c, struct sshbuf *m, struct sshbuf *reply)
337 {
338 Channel *nc;
339 struct mux_session_confirm_ctx *cctx;
340 char *cmd, *cp;
341 u_int i, j, env_len, escape_char, window, packetmax;
342 int r, new_fd[3];
343
344 /* Reply for SSHMUX_COMMAND_OPEN */
345 cctx = xcalloc(1, sizeof(*cctx));
346 cctx->term = NULL;
347 cctx->rid = rid;
348 cmd = NULL;
349 cctx->env = NULL;
350 env_len = 0;
351 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
352 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 ||
353 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 ||
354 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 ||
355 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 ||
356 (r = sshbuf_get_u32(m, &escape_char)) != 0 ||
357 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 ||
358 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) {
359 malf:
360 free(cmd);
361 for (j = 0; j < env_len; j++)
362 free(cctx->env[j]);
363 free(cctx->env);
364 free(cctx->term);
365 free(cctx);
366 error("%s: malformed message", __func__);
367 return -1;
368 }
369
370 #define MUX_MAX_ENV_VARS 4096
371 while (sshbuf_len(m) > 0) {
372 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0)
373 goto malf;
374 if (!env_permitted(cp)) {
375 free(cp);
376 continue;
377 }
378 cctx->env = xreallocarray(cctx->env, env_len + 2,
379 sizeof(*cctx->env));
380 cctx->env[env_len++] = cp;
381 cctx->env[env_len] = NULL;
382 if (env_len > MUX_MAX_ENV_VARS) {
383 error("%s: >%d environment variables received, "
384 "ignoring additional", __func__, MUX_MAX_ENV_VARS);
385 break;
386 }
387 }
388
389 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, "
390 "term \"%s\", cmd \"%s\", env %u", __func__, c->self,
391 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
392 cctx->want_subsys, cctx->term, cmd, env_len);
393
394 if ((cctx->cmd = sshbuf_new()) == NULL)
395 fatal("%s: sshbuf_new", __func__);
396 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0)
397 fatal("%s: sshbuf_put: %s", __func__, ssh_err(r));
398 free(cmd);
399 cmd = NULL;
400
401 /* Gather fds from client */
402 for(i = 0; i < 3; i++) {
403 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
404 error("%s: failed to receive fd %d from slave",
405 __func__, i);
406 for (j = 0; j < i; j++)
407 close(new_fd[j]);
408 for (j = 0; j < env_len; j++)
409 free(cctx->env[j]);
410 free(cctx->env);
411 free(cctx->term);
412 sshbuf_free(cctx->cmd);
413 free(cctx);
414 reply_error(reply, MUX_S_FAILURE, rid,
415 "did not receive file descriptors");
416 return -1;
417 }
418 }
419
420 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
421 new_fd[0], new_fd[1], new_fd[2]);
422
423 /* XXX support multiple child sessions in future */
424 if (c->have_remote_id) {
425 debug2("%s: session already open", __func__);
426 reply_error(reply, MUX_S_FAILURE, rid,
427 "Multiple sessions not supported");
428 cleanup:
429 close(new_fd[0]);
430 close(new_fd[1]);
431 close(new_fd[2]);
432 free(cctx->term);
433 if (env_len != 0) {
434 for (i = 0; i < env_len; i++)
435 free(cctx->env[i]);
436 free(cctx->env);
437 }
438 sshbuf_free(cctx->cmd);
439 free(cctx);
440 return 0;
441 }
442
443 if (options.control_master == SSHCTL_MASTER_ASK ||
444 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
445 if (!ask_permission("Allow shared connection to %s? ", host)) {
446 debug2("%s: session refused by user", __func__);
447 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
448 "Permission denied");
449 goto cleanup;
450 }
451 }
452
453 /* Try to pick up ttymodes from client before it goes raw */
454 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
455 error("%s: tcgetattr: %s", __func__, strerror(errno));
456
457 /* enable nonblocking unless tty */
458 if (!isatty(new_fd[0]))
459 set_nonblock(new_fd[0]);
460 if (!isatty(new_fd[1]))
461 set_nonblock(new_fd[1]);
462 if (!isatty(new_fd[2]))
463 set_nonblock(new_fd[2]);
464
465 window = CHAN_SES_WINDOW_DEFAULT;
466 packetmax = CHAN_SES_PACKET_DEFAULT;
467 if (cctx->want_tty) {
468 window >>= 1;
469 packetmax >>= 1;
470 }
471
472 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
473 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
474 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
475
476 nc->ctl_chan = c->self; /* link session -> control channel */
477 c->remote_id = nc->self; /* link control -> session channel */
478 c->have_remote_id = 1;
479
480 if (cctx->want_tty && escape_char != 0xffffffff) {
481 channel_register_filter(ssh, nc->self,
482 client_simple_escape_filter, NULL,
483 client_filter_cleanup,
484 client_new_escape_filter_ctx((int)escape_char));
485 }
486
487 debug2("%s: channel_new: %d linked to control channel %d",
488 __func__, nc->self, nc->ctl_chan);
489
490 channel_send_open(ssh, nc->self);
491 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx);
492 c->mux_pause = 1; /* stop handling messages until open_confirm done */
493 channel_register_cleanup(ssh, nc->self,
494 mux_master_session_cleanup_cb, 1);
495
496 /* reply is deferred, sent by mux_session_confirm */
497 return 0;
498 }
499
500 static int
mux_master_process_alive_check(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)501 mux_master_process_alive_check(struct ssh *ssh, u_int rid,
502 Channel *c, struct sshbuf *m, struct sshbuf *reply)
503 {
504 int r;
505
506 debug2("%s: channel %d: alive check", __func__, c->self);
507
508 /* prepare reply */
509 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 ||
510 (r = sshbuf_put_u32(reply, rid)) != 0 ||
511 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0)
512 fatal("%s: reply: %s", __func__, ssh_err(r));
513
514 return 0;
515 }
516
517 static int
mux_master_process_terminate(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)518 mux_master_process_terminate(struct ssh *ssh, u_int rid,
519 Channel *c, struct sshbuf *m, struct sshbuf *reply)
520 {
521 debug2("%s: channel %d: terminate request", __func__, c->self);
522
523 if (options.control_master == SSHCTL_MASTER_ASK ||
524 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
525 if (!ask_permission("Terminate shared connection to %s? ",
526 host)) {
527 debug2("%s: termination refused by user", __func__);
528 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
529 "Permission denied");
530 return 0;
531 }
532 }
533
534 quit_pending = 1;
535 reply_ok(reply, rid);
536 /* XXX exit happens too soon - message never makes it to client */
537 return 0;
538 }
539
540 static char *
format_forward(u_int ftype,struct Forward * fwd)541 format_forward(u_int ftype, struct Forward *fwd)
542 {
543 char *ret;
544
545 switch (ftype) {
546 case MUX_FWD_LOCAL:
547 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
548 (fwd->listen_path != NULL) ? fwd->listen_path :
549 (fwd->listen_host == NULL) ?
550 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
551 fwd->listen_host, fwd->listen_port,
552 (fwd->connect_path != NULL) ? fwd->connect_path :
553 fwd->connect_host, fwd->connect_port);
554 break;
555 case MUX_FWD_DYNAMIC:
556 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
557 (fwd->listen_host == NULL) ?
558 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
559 fwd->listen_host, fwd->listen_port);
560 break;
561 case MUX_FWD_REMOTE:
562 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
563 (fwd->listen_path != NULL) ? fwd->listen_path :
564 (fwd->listen_host == NULL) ?
565 "LOCALHOST" : fwd->listen_host,
566 fwd->listen_port,
567 (fwd->connect_path != NULL) ? fwd->connect_path :
568 fwd->connect_host, fwd->connect_port);
569 break;
570 default:
571 fatal("%s: unknown forward type %u", __func__, ftype);
572 }
573 return ret;
574 }
575
576 static int
compare_host(const char * a,const char * b)577 compare_host(const char *a, const char *b)
578 {
579 if (a == NULL && b == NULL)
580 return 1;
581 if (a == NULL || b == NULL)
582 return 0;
583 return strcmp(a, b) == 0;
584 }
585
586 static int
compare_forward(struct Forward * a,struct Forward * b)587 compare_forward(struct Forward *a, struct Forward *b)
588 {
589 if (!compare_host(a->listen_host, b->listen_host))
590 return 0;
591 if (!compare_host(a->listen_path, b->listen_path))
592 return 0;
593 if (a->listen_port != b->listen_port)
594 return 0;
595 if (!compare_host(a->connect_host, b->connect_host))
596 return 0;
597 if (!compare_host(a->connect_path, b->connect_path))
598 return 0;
599 if (a->connect_port != b->connect_port)
600 return 0;
601
602 return 1;
603 }
604
605 static void
mux_confirm_remote_forward(struct ssh * ssh,int type,u_int32_t seq,void * ctxt)606 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
607 {
608 struct mux_channel_confirm_ctx *fctx = ctxt;
609 char *failmsg = NULL;
610 struct Forward *rfwd;
611 Channel *c;
612 struct sshbuf *out;
613 u_int port;
614 int r;
615
616 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) {
617 /* no channel for reply */
618 error("%s: unknown channel", __func__);
619 return;
620 }
621 if ((out = sshbuf_new()) == NULL)
622 fatal("%s: sshbuf_new", __func__);
623 if (fctx->fid >= options.num_remote_forwards ||
624 (options.remote_forwards[fctx->fid].connect_path == NULL &&
625 options.remote_forwards[fctx->fid].connect_host == NULL)) {
626 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
627 goto fail;
628 }
629 rfwd = &options.remote_forwards[fctx->fid];
630 debug("%s: %s for: listen %d, connect %s:%d", __func__,
631 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
632 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
633 rfwd->connect_host, rfwd->connect_port);
634 if (type == SSH2_MSG_REQUEST_SUCCESS) {
635 if (rfwd->listen_port == 0) {
636 if ((r = sshpkt_get_u32(ssh, &port)) != 0)
637 fatal("%s: packet error: %s",
638 __func__, ssh_err(r));
639 if (port > 65535) {
640 fatal("Invalid allocated port %u for "
641 "mux remote forward to %s:%d", port,
642 rfwd->connect_host, rfwd->connect_port);
643 }
644 rfwd->allocated_port = (int)port;
645 debug("Allocated port %u for mux remote forward"
646 " to %s:%d", rfwd->allocated_port,
647 rfwd->connect_host, rfwd->connect_port);
648 if ((r = sshbuf_put_u32(out,
649 MUX_S_REMOTE_PORT)) != 0 ||
650 (r = sshbuf_put_u32(out, fctx->rid)) != 0 ||
651 (r = sshbuf_put_u32(out,
652 rfwd->allocated_port)) != 0)
653 fatal("%s: reply: %s", __func__, ssh_err(r));
654 channel_update_permission(ssh, rfwd->handle,
655 rfwd->allocated_port);
656 } else {
657 reply_ok(out, fctx->rid);
658 }
659 goto out;
660 } else {
661 if (rfwd->listen_port == 0)
662 channel_update_permission(ssh, rfwd->handle, -1);
663 if (rfwd->listen_path != NULL)
664 xasprintf(&failmsg, "remote port forwarding failed for "
665 "listen path %s", rfwd->listen_path);
666 else
667 xasprintf(&failmsg, "remote port forwarding failed for "
668 "listen port %d", rfwd->listen_port);
669
670 debug2("%s: clearing registered forwarding for listen %d, "
671 "connect %s:%d", __func__, rfwd->listen_port,
672 rfwd->connect_path ? rfwd->connect_path :
673 rfwd->connect_host, rfwd->connect_port);
674
675 free(rfwd->listen_host);
676 free(rfwd->listen_path);
677 free(rfwd->connect_host);
678 free(rfwd->connect_path);
679 memset(rfwd, 0, sizeof(*rfwd));
680 }
681 fail:
682 error("%s: %s", __func__, failmsg);
683 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg);
684 free(failmsg);
685 out:
686 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
687 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
688 sshbuf_free(out);
689 if (c->mux_pause <= 0)
690 fatal("%s: mux_pause %d", __func__, c->mux_pause);
691 c->mux_pause = 0; /* start processing messages again */
692 }
693
694 static int
mux_master_process_open_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)695 mux_master_process_open_fwd(struct ssh *ssh, u_int rid,
696 Channel *c, struct sshbuf *m, struct sshbuf *reply)
697 {
698 struct Forward fwd;
699 char *fwd_desc = NULL;
700 char *listen_addr, *connect_addr;
701 u_int ftype;
702 u_int lport, cport;
703 int r, i, ret = 0, freefwd = 1;
704
705 memset(&fwd, 0, sizeof(fwd));
706
707 /* XXX - lport/cport check redundant */
708 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
709 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
710 (r = sshbuf_get_u32(m, &lport)) != 0 ||
711 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
712 (r = sshbuf_get_u32(m, &cport)) != 0 ||
713 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
714 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
715 error("%s: malformed message", __func__);
716 ret = -1;
717 goto out;
718 }
719 if (*listen_addr == '\0') {
720 free(listen_addr);
721 listen_addr = NULL;
722 }
723 if (*connect_addr == '\0') {
724 free(connect_addr);
725 connect_addr = NULL;
726 }
727
728 memset(&fwd, 0, sizeof(fwd));
729 fwd.listen_port = lport;
730 if (fwd.listen_port == PORT_STREAMLOCAL)
731 fwd.listen_path = listen_addr;
732 else
733 fwd.listen_host = listen_addr;
734 fwd.connect_port = cport;
735 if (fwd.connect_port == PORT_STREAMLOCAL)
736 fwd.connect_path = connect_addr;
737 else
738 fwd.connect_host = connect_addr;
739
740 debug2("%s: channel %d: request %s", __func__, c->self,
741 (fwd_desc = format_forward(ftype, &fwd)));
742
743 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
744 ftype != MUX_FWD_DYNAMIC) {
745 logit("%s: invalid forwarding type %u", __func__, ftype);
746 invalid:
747 free(listen_addr);
748 free(connect_addr);
749 reply_error(reply, MUX_S_FAILURE, rid,
750 "Invalid forwarding request");
751 return 0;
752 }
753 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) {
754 logit("%s: streamlocal and dynamic forwards "
755 "are mutually exclusive", __func__);
756 goto invalid;
757 }
758 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) {
759 logit("%s: invalid listen port %u", __func__,
760 fwd.listen_port);
761 goto invalid;
762 }
763 if ((fwd.connect_port != PORT_STREAMLOCAL &&
764 fwd.connect_port >= 65536) ||
765 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE &&
766 fwd.connect_port == 0)) {
767 logit("%s: invalid connect port %u", __func__,
768 fwd.connect_port);
769 goto invalid;
770 }
771 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL &&
772 fwd.connect_path == NULL) {
773 logit("%s: missing connect host", __func__);
774 goto invalid;
775 }
776
777 /* Skip forwards that have already been requested */
778 switch (ftype) {
779 case MUX_FWD_LOCAL:
780 case MUX_FWD_DYNAMIC:
781 for (i = 0; i < options.num_local_forwards; i++) {
782 if (compare_forward(&fwd,
783 options.local_forwards + i)) {
784 exists:
785 debug2("%s: found existing forwarding",
786 __func__);
787 reply_ok(reply, rid);
788 goto out;
789 }
790 }
791 break;
792 case MUX_FWD_REMOTE:
793 for (i = 0; i < options.num_remote_forwards; i++) {
794 if (!compare_forward(&fwd, options.remote_forwards + i))
795 continue;
796 if (fwd.listen_port != 0)
797 goto exists;
798 debug2("%s: found allocated port", __func__);
799 if ((r = sshbuf_put_u32(reply,
800 MUX_S_REMOTE_PORT)) != 0 ||
801 (r = sshbuf_put_u32(reply, rid)) != 0 ||
802 (r = sshbuf_put_u32(reply,
803 options.remote_forwards[i].allocated_port)) != 0)
804 fatal("%s: reply: %s", __func__, ssh_err(r));
805 goto out;
806 }
807 break;
808 }
809
810 if (options.control_master == SSHCTL_MASTER_ASK ||
811 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
812 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
813 debug2("%s: forwarding refused by user", __func__);
814 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
815 "Permission denied");
816 goto out;
817 }
818 }
819
820 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
821 if (!channel_setup_local_fwd_listener(ssh, &fwd,
822 &options.fwd_opts)) {
823 fail:
824 logit("%s: requested %s failed", __func__, fwd_desc);
825 reply_error(reply, MUX_S_FAILURE, rid,
826 "Port forwarding failed");
827 goto out;
828 }
829 add_local_forward(&options, &fwd);
830 freefwd = 0;
831 } else {
832 struct mux_channel_confirm_ctx *fctx;
833
834 fwd.handle = channel_request_remote_forwarding(ssh, &fwd);
835 if (fwd.handle < 0)
836 goto fail;
837 add_remote_forward(&options, &fwd);
838 fctx = xcalloc(1, sizeof(*fctx));
839 fctx->cid = c->self;
840 fctx->rid = rid;
841 fctx->fid = options.num_remote_forwards - 1;
842 client_register_global_confirm(mux_confirm_remote_forward,
843 fctx);
844 freefwd = 0;
845 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
846 /* delayed reply in mux_confirm_remote_forward */
847 goto out;
848 }
849 reply_ok(reply, rid);
850 out:
851 free(fwd_desc);
852 if (freefwd) {
853 free(fwd.listen_host);
854 free(fwd.listen_path);
855 free(fwd.connect_host);
856 free(fwd.connect_path);
857 }
858 return ret;
859 }
860
861 static int
mux_master_process_close_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)862 mux_master_process_close_fwd(struct ssh *ssh, u_int rid,
863 Channel *c, struct sshbuf *m, struct sshbuf *reply)
864 {
865 struct Forward fwd, *found_fwd;
866 char *fwd_desc = NULL;
867 const char *error_reason = NULL;
868 char *listen_addr = NULL, *connect_addr = NULL;
869 u_int ftype;
870 int r, i, ret = 0;
871 u_int lport, cport;
872
873 memset(&fwd, 0, sizeof(fwd));
874
875 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
876 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
877 (r = sshbuf_get_u32(m, &lport)) != 0 ||
878 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
879 (r = sshbuf_get_u32(m, &cport)) != 0 ||
880 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
881 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
882 error("%s: malformed message", __func__);
883 ret = -1;
884 goto out;
885 }
886
887 if (*listen_addr == '\0') {
888 free(listen_addr);
889 listen_addr = NULL;
890 }
891 if (*connect_addr == '\0') {
892 free(connect_addr);
893 connect_addr = NULL;
894 }
895
896 memset(&fwd, 0, sizeof(fwd));
897 fwd.listen_port = lport;
898 if (fwd.listen_port == PORT_STREAMLOCAL)
899 fwd.listen_path = listen_addr;
900 else
901 fwd.listen_host = listen_addr;
902 fwd.connect_port = cport;
903 if (fwd.connect_port == PORT_STREAMLOCAL)
904 fwd.connect_path = connect_addr;
905 else
906 fwd.connect_host = connect_addr;
907
908 debug2("%s: channel %d: request cancel %s", __func__, c->self,
909 (fwd_desc = format_forward(ftype, &fwd)));
910
911 /* make sure this has been requested */
912 found_fwd = NULL;
913 switch (ftype) {
914 case MUX_FWD_LOCAL:
915 case MUX_FWD_DYNAMIC:
916 for (i = 0; i < options.num_local_forwards; i++) {
917 if (compare_forward(&fwd,
918 options.local_forwards + i)) {
919 found_fwd = options.local_forwards + i;
920 break;
921 }
922 }
923 break;
924 case MUX_FWD_REMOTE:
925 for (i = 0; i < options.num_remote_forwards; i++) {
926 if (compare_forward(&fwd,
927 options.remote_forwards + i)) {
928 found_fwd = options.remote_forwards + i;
929 break;
930 }
931 }
932 break;
933 }
934
935 if (found_fwd == NULL)
936 error_reason = "port not forwarded";
937 else if (ftype == MUX_FWD_REMOTE) {
938 /*
939 * This shouldn't fail unless we confused the host/port
940 * between options.remote_forwards and permitted_opens.
941 * However, for dynamic allocated listen ports we need
942 * to use the actual listen port.
943 */
944 if (channel_request_rforward_cancel(ssh, found_fwd) == -1)
945 error_reason = "port not in permitted opens";
946 } else { /* local and dynamic forwards */
947 /* Ditto */
948 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port,
949 &options.fwd_opts) == -1)
950 error_reason = "port not found";
951 }
952
953 if (error_reason != NULL)
954 reply_error(reply, MUX_S_FAILURE, rid, error_reason);
955 else {
956 reply_ok(reply, rid);
957 free(found_fwd->listen_host);
958 free(found_fwd->listen_path);
959 free(found_fwd->connect_host);
960 free(found_fwd->connect_path);
961 found_fwd->listen_host = found_fwd->connect_host = NULL;
962 found_fwd->listen_path = found_fwd->connect_path = NULL;
963 found_fwd->listen_port = found_fwd->connect_port = 0;
964 }
965 out:
966 free(fwd_desc);
967 free(listen_addr);
968 free(connect_addr);
969
970 return ret;
971 }
972
973 static int
mux_master_process_stdio_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)974 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid,
975 Channel *c, struct sshbuf *m, struct sshbuf *reply)
976 {
977 Channel *nc;
978 char *chost = NULL;
979 u_int cport, i, j;
980 int r, new_fd[2];
981 struct mux_stdio_confirm_ctx *cctx;
982
983 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
984 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
985 (r = sshbuf_get_u32(m, &cport)) != 0) {
986 free(chost);
987 error("%s: malformed message", __func__);
988 return -1;
989 }
990
991 debug2("%s: channel %d: request stdio fwd to %s:%u",
992 __func__, c->self, chost, cport);
993
994 /* Gather fds from client */
995 for(i = 0; i < 2; i++) {
996 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
997 error("%s: failed to receive fd %d from slave",
998 __func__, i);
999 for (j = 0; j < i; j++)
1000 close(new_fd[j]);
1001 free(chost);
1002
1003 /* prepare reply */
1004 reply_error(reply, MUX_S_FAILURE, rid,
1005 "did not receive file descriptors");
1006 return -1;
1007 }
1008 }
1009
1010 debug3("%s: got fds stdin %d, stdout %d", __func__,
1011 new_fd[0], new_fd[1]);
1012
1013 /* XXX support multiple child sessions in future */
1014 if (c->have_remote_id) {
1015 debug2("%s: session already open", __func__);
1016 reply_error(reply, MUX_S_FAILURE, rid,
1017 "Multiple sessions not supported");
1018 cleanup:
1019 close(new_fd[0]);
1020 close(new_fd[1]);
1021 free(chost);
1022 return 0;
1023 }
1024
1025 if (options.control_master == SSHCTL_MASTER_ASK ||
1026 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1027 if (!ask_permission("Allow forward to %s:%u? ",
1028 chost, cport)) {
1029 debug2("%s: stdio fwd refused by user", __func__);
1030 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1031 "Permission denied");
1032 goto cleanup;
1033 }
1034 }
1035
1036 /* enable nonblocking unless tty */
1037 if (!isatty(new_fd[0]))
1038 set_nonblock(new_fd[0]);
1039 if (!isatty(new_fd[1]))
1040 set_nonblock(new_fd[1]);
1041
1042 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]);
1043 free(chost);
1044
1045 nc->ctl_chan = c->self; /* link session -> control channel */
1046 c->remote_id = nc->self; /* link control -> session channel */
1047 c->have_remote_id = 1;
1048
1049 debug2("%s: channel_new: %d linked to control channel %d",
1050 __func__, nc->self, nc->ctl_chan);
1051
1052 channel_register_cleanup(ssh, nc->self,
1053 mux_master_session_cleanup_cb, 1);
1054
1055 cctx = xcalloc(1, sizeof(*cctx));
1056 cctx->rid = rid;
1057 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx);
1058 c->mux_pause = 1; /* stop handling messages until open_confirm done */
1059
1060 /* reply is deferred, sent by mux_session_confirm */
1061 return 0;
1062 }
1063
1064 /* Callback on open confirmation in mux master for a mux stdio fwd session. */
1065 static void
mux_stdio_confirm(struct ssh * ssh,int id,int success,void * arg)1066 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1067 {
1068 struct mux_stdio_confirm_ctx *cctx = arg;
1069 Channel *c, *cc;
1070 struct sshbuf *reply;
1071 int r;
1072
1073 if (cctx == NULL)
1074 fatal("%s: cctx == NULL", __func__);
1075 if ((c = channel_by_id(ssh, id)) == NULL)
1076 fatal("%s: no channel for id %d", __func__, id);
1077 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1078 fatal("%s: channel %d lacks control channel %d", __func__,
1079 id, c->ctl_chan);
1080 if ((reply = sshbuf_new()) == NULL)
1081 fatal("%s: sshbuf_new", __func__);
1082
1083 if (!success) {
1084 debug3("%s: sending failure reply", __func__);
1085 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1086 "Session open refused by peer");
1087 /* prepare reply */
1088 goto done;
1089 }
1090
1091 debug3("%s: sending success reply", __func__);
1092 /* prepare reply */
1093 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1094 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1095 (r = sshbuf_put_u32(reply, c->self)) != 0)
1096 fatal("%s: reply: %s", __func__, ssh_err(r));
1097
1098 done:
1099 /* Send reply */
1100 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1101 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
1102 sshbuf_free(reply);
1103
1104 if (cc->mux_pause <= 0)
1105 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1106 cc->mux_pause = 0; /* start processing messages again */
1107 c->open_confirm_ctx = NULL;
1108 free(cctx);
1109 }
1110
1111 static int
mux_master_process_stop_listening(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1112 mux_master_process_stop_listening(struct ssh *ssh, u_int rid,
1113 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1114 {
1115 debug("%s: channel %d: stop listening", __func__, c->self);
1116
1117 if (options.control_master == SSHCTL_MASTER_ASK ||
1118 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1119 if (!ask_permission("Disable further multiplexing on shared "
1120 "connection to %s? ", host)) {
1121 debug2("%s: stop listen refused by user", __func__);
1122 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1123 "Permission denied");
1124 return 0;
1125 }
1126 }
1127
1128 if (mux_listener_channel != NULL) {
1129 channel_free(ssh, mux_listener_channel);
1130 client_stop_mux();
1131 free(options.control_path);
1132 options.control_path = NULL;
1133 mux_listener_channel = NULL;
1134 muxserver_sock = -1;
1135 }
1136
1137 reply_ok(reply, rid);
1138 return 0;
1139 }
1140
1141 static int
mux_master_process_proxy(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1142 mux_master_process_proxy(struct ssh *ssh, u_int rid,
1143 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1144 {
1145 int r;
1146
1147 debug("%s: channel %d: proxy request", __func__, c->self);
1148
1149 c->mux_rcb = channel_proxy_downstream;
1150 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 ||
1151 (r = sshbuf_put_u32(reply, rid)) != 0)
1152 fatal("%s: reply: %s", __func__, ssh_err(r));
1153
1154 return 0;
1155 }
1156
1157 /* Channel callbacks fired on read/write from mux slave fd */
1158 static int
mux_master_read_cb(struct ssh * ssh,Channel * c)1159 mux_master_read_cb(struct ssh *ssh, Channel *c)
1160 {
1161 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
1162 struct sshbuf *in = NULL, *out = NULL;
1163 u_int type, rid, i;
1164 int r, ret = -1;
1165
1166 if ((out = sshbuf_new()) == NULL)
1167 fatal("%s: sshbuf_new", __func__);
1168
1169 /* Setup ctx and */
1170 if (c->mux_ctx == NULL) {
1171 state = xcalloc(1, sizeof(*state));
1172 c->mux_ctx = state;
1173 channel_register_cleanup(ssh, c->self,
1174 mux_master_control_cleanup_cb, 0);
1175
1176 /* Send hello */
1177 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 ||
1178 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0)
1179 fatal("%s: reply: %s", __func__, ssh_err(r));
1180 /* no extensions */
1181 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
1182 fatal("%s: sshbuf_put_stringb: %s",
1183 __func__, ssh_err(r));
1184 debug3("%s: channel %d: hello sent", __func__, c->self);
1185 ret = 0;
1186 goto out;
1187 }
1188
1189 /* Channel code ensures that we receive whole packets */
1190 if ((r = sshbuf_froms(c->input, &in)) != 0) {
1191 malf:
1192 error("%s: malformed message", __func__);
1193 goto out;
1194 }
1195
1196 if ((r = sshbuf_get_u32(in, &type)) != 0)
1197 goto malf;
1198 debug3("%s: channel %d packet type 0x%08x len %zu",
1199 __func__, c->self, type, sshbuf_len(in));
1200
1201 if (type == MUX_MSG_HELLO)
1202 rid = 0;
1203 else {
1204 if (!state->hello_rcvd) {
1205 error("%s: expected MUX_MSG_HELLO(0x%08x), "
1206 "received 0x%08x", __func__, MUX_MSG_HELLO, type);
1207 goto out;
1208 }
1209 if ((r = sshbuf_get_u32(in, &rid)) != 0)
1210 goto malf;
1211 }
1212
1213 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
1214 if (type == mux_master_handlers[i].type) {
1215 ret = mux_master_handlers[i].handler(ssh, rid,
1216 c, in, out);
1217 break;
1218 }
1219 }
1220 if (mux_master_handlers[i].handler == NULL) {
1221 error("%s: unsupported mux message 0x%08x", __func__, type);
1222 reply_error(out, MUX_S_FAILURE, rid, "unsupported request");
1223 ret = 0;
1224 }
1225 /* Enqueue reply packet */
1226 if (sshbuf_len(out) != 0) {
1227 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
1228 fatal("%s: sshbuf_put_stringb: %s",
1229 __func__, ssh_err(r));
1230 }
1231 out:
1232 sshbuf_free(in);
1233 sshbuf_free(out);
1234 return ret;
1235 }
1236
1237 void
mux_exit_message(struct ssh * ssh,Channel * c,int exitval)1238 mux_exit_message(struct ssh *ssh, Channel *c, int exitval)
1239 {
1240 struct sshbuf *m;
1241 Channel *mux_chan;
1242 int r;
1243
1244 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self,
1245 exitval);
1246
1247 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1248 fatal("%s: channel %d missing mux channel %d",
1249 __func__, c->self, c->ctl_chan);
1250
1251 /* Append exit message packet to control socket output queue */
1252 if ((m = sshbuf_new()) == NULL)
1253 fatal("%s: sshbuf_new", __func__);
1254 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 ||
1255 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1256 (r = sshbuf_put_u32(m, exitval)) != 0 ||
1257 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1258 fatal("%s: reply: %s", __func__, ssh_err(r));
1259 sshbuf_free(m);
1260 }
1261
1262 void
mux_tty_alloc_failed(struct ssh * ssh,Channel * c)1263 mux_tty_alloc_failed(struct ssh *ssh, Channel *c)
1264 {
1265 struct sshbuf *m;
1266 Channel *mux_chan;
1267 int r;
1268
1269 debug3("%s: channel %d: TTY alloc failed", __func__, c->self);
1270
1271 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1272 fatal("%s: channel %d missing mux channel %d",
1273 __func__, c->self, c->ctl_chan);
1274
1275 /* Append exit message packet to control socket output queue */
1276 if ((m = sshbuf_new()) == NULL)
1277 fatal("%s: sshbuf_new", __func__);
1278 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 ||
1279 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1280 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1281 fatal("%s: reply: %s", __func__, ssh_err(r));
1282 sshbuf_free(m);
1283 }
1284
1285 /* Prepare a mux master to listen on a Unix domain socket. */
1286 void
muxserver_listen(struct ssh * ssh)1287 muxserver_listen(struct ssh *ssh)
1288 {
1289 mode_t old_umask;
1290 char *orig_control_path = options.control_path;
1291 char rbuf[16+1];
1292 u_int i, r;
1293 int oerrno;
1294
1295 if (options.control_path == NULL ||
1296 options.control_master == SSHCTL_MASTER_NO)
1297 return;
1298
1299 debug("setting up multiplex master socket");
1300
1301 /*
1302 * Use a temporary path before listen so we can pseudo-atomically
1303 * establish the listening socket in its final location to avoid
1304 * other processes racing in between bind() and listen() and hitting
1305 * an unready socket.
1306 */
1307 for (i = 0; i < sizeof(rbuf) - 1; i++) {
1308 r = arc4random_uniform(26+26+10);
1309 rbuf[i] = (r < 26) ? 'a' + r :
1310 (r < 26*2) ? 'A' + r - 26 :
1311 '0' + r - 26 - 26;
1312 }
1313 rbuf[sizeof(rbuf) - 1] = '\0';
1314 options.control_path = NULL;
1315 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
1316 debug3("%s: temporary control path %s", __func__, options.control_path);
1317
1318 old_umask = umask(0177);
1319 muxserver_sock = unix_listener(options.control_path, 64, 0);
1320 oerrno = errno;
1321 umask(old_umask);
1322 if (muxserver_sock < 0) {
1323 if (oerrno == EINVAL || oerrno == EADDRINUSE) {
1324 error("ControlSocket %s already exists, "
1325 "disabling multiplexing", options.control_path);
1326 disable_mux_master:
1327 if (muxserver_sock != -1) {
1328 close(muxserver_sock);
1329 muxserver_sock = -1;
1330 }
1331 free(orig_control_path);
1332 free(options.control_path);
1333 options.control_path = NULL;
1334 options.control_master = SSHCTL_MASTER_NO;
1335 return;
1336 } else {
1337 /* unix_listener() logs the error */
1338 cleanup_exit(255);
1339 }
1340 }
1341
1342 /* Now atomically "move" the mux socket into position */
1343 if (link(options.control_path, orig_control_path) != 0) {
1344 if (errno != EEXIST) {
1345 fatal("%s: link mux listener %s => %s: %s", __func__,
1346 options.control_path, orig_control_path,
1347 strerror(errno));
1348 }
1349 error("ControlSocket %s already exists, disabling multiplexing",
1350 orig_control_path);
1351 unlink(options.control_path);
1352 goto disable_mux_master;
1353 }
1354 unlink(options.control_path);
1355 free(options.control_path);
1356 options.control_path = orig_control_path;
1357
1358 set_nonblock(muxserver_sock);
1359
1360 mux_listener_channel = channel_new(ssh, "mux listener",
1361 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
1362 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1363 0, options.control_path, 1);
1364 mux_listener_channel->mux_rcb = mux_master_read_cb;
1365 debug3("%s: mux listener channel %d fd %d", __func__,
1366 mux_listener_channel->self, mux_listener_channel->sock);
1367 }
1368
1369 /* Callback on open confirmation in mux master for a mux client session. */
1370 static void
mux_session_confirm(struct ssh * ssh,int id,int success,void * arg)1371 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg)
1372 {
1373 struct mux_session_confirm_ctx *cctx = arg;
1374 const char *display;
1375 Channel *c, *cc;
1376 int i, r;
1377 struct sshbuf *reply;
1378
1379 if (cctx == NULL)
1380 fatal("%s: cctx == NULL", __func__);
1381 if ((c = channel_by_id(ssh, id)) == NULL)
1382 fatal("%s: no channel for id %d", __func__, id);
1383 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1384 fatal("%s: channel %d lacks control channel %d", __func__,
1385 id, c->ctl_chan);
1386 if ((reply = sshbuf_new()) == NULL)
1387 fatal("%s: sshbuf_new", __func__);
1388
1389 if (!success) {
1390 debug3("%s: sending failure reply", __func__);
1391 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1392 "Session open refused by peer");
1393 goto done;
1394 }
1395
1396 display = getenv("DISPLAY");
1397 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1398 char *proto, *data;
1399
1400 /* Get reasonable local authentication information. */
1401 if (client_x11_get_proto(ssh, display, options.xauth_location,
1402 options.forward_x11_trusted, options.forward_x11_timeout,
1403 &proto, &data) == 0) {
1404 /* Request forwarding with authentication spoofing. */
1405 debug("Requesting X11 forwarding with authentication "
1406 "spoofing.");
1407 x11_request_forwarding_with_spoofing(ssh, id,
1408 display, proto, data, 1);
1409 /* XXX exit_on_forward_failure */
1410 client_expect_confirm(ssh, id, "X11 forwarding",
1411 CONFIRM_WARN);
1412 }
1413 }
1414
1415 if (cctx->want_agent_fwd && options.forward_agent) {
1416 debug("Requesting authentication agent forwarding.");
1417 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
1418 if ((r = sshpkt_send(ssh)) != 0)
1419 fatal("%s: packet error: %s", __func__, ssh_err(r));
1420 }
1421
1422 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys,
1423 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env);
1424
1425 debug3("%s: sending success reply", __func__);
1426 /* prepare reply */
1427 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1428 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1429 (r = sshbuf_put_u32(reply, c->self)) != 0)
1430 fatal("%s: reply: %s", __func__, ssh_err(r));
1431
1432 done:
1433 /* Send reply */
1434 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1435 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
1436 sshbuf_free(reply);
1437
1438 if (cc->mux_pause <= 0)
1439 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1440 cc->mux_pause = 0; /* start processing messages again */
1441 c->open_confirm_ctx = NULL;
1442 sshbuf_free(cctx->cmd);
1443 free(cctx->term);
1444 if (cctx->env != NULL) {
1445 for (i = 0; cctx->env[i] != NULL; i++)
1446 free(cctx->env[i]);
1447 free(cctx->env);
1448 }
1449 free(cctx);
1450 }
1451
1452 /* ** Multiplexing client support */
1453
1454 /* Exit signal handler */
1455 static void
control_client_sighandler(int signo)1456 control_client_sighandler(int signo)
1457 {
1458 muxclient_terminate = signo;
1459 }
1460
1461 /*
1462 * Relay signal handler - used to pass some signals from mux client to
1463 * mux master.
1464 */
1465 static void
control_client_sigrelay(int signo)1466 control_client_sigrelay(int signo)
1467 {
1468 int save_errno = errno;
1469
1470 if (muxserver_pid > 1)
1471 kill(muxserver_pid, signo);
1472
1473 errno = save_errno;
1474 }
1475
1476 static int
mux_client_read(int fd,struct sshbuf * b,size_t need)1477 mux_client_read(int fd, struct sshbuf *b, size_t need)
1478 {
1479 size_t have;
1480 ssize_t len;
1481 u_char *p;
1482 struct pollfd pfd;
1483 int r;
1484
1485 pfd.fd = fd;
1486 pfd.events = POLLIN;
1487 if ((r = sshbuf_reserve(b, need, &p)) != 0)
1488 fatal("%s: reserve: %s", __func__, ssh_err(r));
1489 for (have = 0; have < need; ) {
1490 if (muxclient_terminate) {
1491 errno = EINTR;
1492 return -1;
1493 }
1494 len = read(fd, p + have, need - have);
1495 if (len == -1) {
1496 switch (errno) {
1497 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1498 case EWOULDBLOCK:
1499 #endif
1500 case EAGAIN:
1501 (void)poll(&pfd, 1, -1);
1502 /* FALLTHROUGH */
1503 case EINTR:
1504 continue;
1505 default:
1506 return -1;
1507 }
1508 }
1509 if (len == 0) {
1510 errno = EPIPE;
1511 return -1;
1512 }
1513 have += (size_t)len;
1514 }
1515 return 0;
1516 }
1517
1518 static int
mux_client_write_packet(int fd,struct sshbuf * m)1519 mux_client_write_packet(int fd, struct sshbuf *m)
1520 {
1521 struct sshbuf *queue;
1522 u_int have, need;
1523 int r, oerrno, len;
1524 const u_char *ptr;
1525 struct pollfd pfd;
1526
1527 pfd.fd = fd;
1528 pfd.events = POLLOUT;
1529 if ((queue = sshbuf_new()) == NULL)
1530 fatal("%s: sshbuf_new", __func__);
1531 if ((r = sshbuf_put_stringb(queue, m)) != 0)
1532 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
1533
1534 need = sshbuf_len(queue);
1535 ptr = sshbuf_ptr(queue);
1536
1537 for (have = 0; have < need; ) {
1538 if (muxclient_terminate) {
1539 sshbuf_free(queue);
1540 errno = EINTR;
1541 return -1;
1542 }
1543 len = write(fd, ptr + have, need - have);
1544 if (len == -1) {
1545 switch (errno) {
1546 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1547 case EWOULDBLOCK:
1548 #endif
1549 case EAGAIN:
1550 (void)poll(&pfd, 1, -1);
1551 /* FALLTHROUGH */
1552 case EINTR:
1553 continue;
1554 default:
1555 oerrno = errno;
1556 sshbuf_free(queue);
1557 errno = oerrno;
1558 return -1;
1559 }
1560 }
1561 if (len == 0) {
1562 sshbuf_free(queue);
1563 errno = EPIPE;
1564 return -1;
1565 }
1566 have += (u_int)len;
1567 }
1568 sshbuf_free(queue);
1569 return 0;
1570 }
1571
1572 static int
mux_client_read_packet(int fd,struct sshbuf * m)1573 mux_client_read_packet(int fd, struct sshbuf *m)
1574 {
1575 struct sshbuf *queue;
1576 size_t need, have;
1577 const u_char *ptr;
1578 int r, oerrno;
1579
1580 if ((queue = sshbuf_new()) == NULL)
1581 fatal("%s: sshbuf_new", __func__);
1582 if (mux_client_read(fd, queue, 4) != 0) {
1583 if ((oerrno = errno) == EPIPE)
1584 debug3("%s: read header failed: %s", __func__,
1585 strerror(errno));
1586 sshbuf_free(queue);
1587 errno = oerrno;
1588 return -1;
1589 }
1590 need = PEEK_U32(sshbuf_ptr(queue));
1591 if (mux_client_read(fd, queue, need) != 0) {
1592 oerrno = errno;
1593 debug3("%s: read body failed: %s", __func__, strerror(errno));
1594 sshbuf_free(queue);
1595 errno = oerrno;
1596 return -1;
1597 }
1598 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 ||
1599 (r = sshbuf_put(m, ptr, have)) != 0)
1600 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1601 sshbuf_free(queue);
1602 return 0;
1603 }
1604
1605 static int
mux_client_hello_exchange(int fd)1606 mux_client_hello_exchange(int fd)
1607 {
1608 struct sshbuf *m;
1609 u_int type, ver;
1610 int r, ret = -1;
1611
1612 if ((m = sshbuf_new()) == NULL)
1613 fatal("%s: sshbuf_new", __func__);
1614 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 ||
1615 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0)
1616 fatal("%s: hello: %s", __func__, ssh_err(r));
1617 /* no extensions */
1618
1619 if (mux_client_write_packet(fd, m) != 0) {
1620 debug("%s: write packet: %s", __func__, strerror(errno));
1621 goto out;
1622 }
1623
1624 sshbuf_reset(m);
1625
1626 /* Read their HELLO */
1627 if (mux_client_read_packet(fd, m) != 0) {
1628 debug("%s: read packet failed", __func__);
1629 goto out;
1630 }
1631
1632 if ((r = sshbuf_get_u32(m, &type)) != 0)
1633 fatal("%s: decode type: %s", __func__, ssh_err(r));
1634 if (type != MUX_MSG_HELLO) {
1635 error("%s: expected HELLO (%u) received %u",
1636 __func__, MUX_MSG_HELLO, type);
1637 goto out;
1638 }
1639 if ((r = sshbuf_get_u32(m, &ver)) != 0)
1640 fatal("%s: decode version: %s", __func__, ssh_err(r));
1641 if (ver != SSHMUX_VER) {
1642 error("Unsupported multiplexing protocol version %d "
1643 "(expected %d)", ver, SSHMUX_VER);
1644 goto out;
1645 }
1646 debug2("%s: master version %u", __func__, ver);
1647 /* No extensions are presently defined */
1648 while (sshbuf_len(m) > 0) {
1649 char *name = NULL;
1650
1651 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
1652 (r = sshbuf_skip_string(m)) != 0) { /* value */
1653 error("%s: malformed extension: %s",
1654 __func__, ssh_err(r));
1655 goto out;
1656 }
1657 debug2("Unrecognised master extension \"%s\"", name);
1658 free(name);
1659 }
1660 /* success */
1661 ret = 0;
1662 out:
1663 sshbuf_free(m);
1664 return ret;
1665 }
1666
1667 static u_int
mux_client_request_alive(int fd)1668 mux_client_request_alive(int fd)
1669 {
1670 struct sshbuf *m;
1671 char *e;
1672 u_int pid, type, rid;
1673 int r;
1674
1675 debug3("%s: entering", __func__);
1676
1677 if ((m = sshbuf_new()) == NULL)
1678 fatal("%s: sshbuf_new", __func__);
1679 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 ||
1680 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1681 fatal("%s: request: %s", __func__, ssh_err(r));
1682
1683 if (mux_client_write_packet(fd, m) != 0)
1684 fatal("%s: write packet: %s", __func__, strerror(errno));
1685
1686 sshbuf_reset(m);
1687
1688 /* Read their reply */
1689 if (mux_client_read_packet(fd, m) != 0) {
1690 sshbuf_free(m);
1691 return 0;
1692 }
1693
1694 if ((r = sshbuf_get_u32(m, &type)) != 0)
1695 fatal("%s: decode type: %s", __func__, ssh_err(r));
1696 if (type != MUX_S_ALIVE) {
1697 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1698 fatal("%s: decode error: %s", __func__, ssh_err(r));
1699 fatal("%s: master returned error: %s", __func__, e);
1700 }
1701
1702 if ((r = sshbuf_get_u32(m, &rid)) != 0)
1703 fatal("%s: decode remote ID: %s", __func__, ssh_err(r));
1704 if (rid != muxclient_request_id)
1705 fatal("%s: out of sequence reply: my id %u theirs %u",
1706 __func__, muxclient_request_id, rid);
1707 if ((r = sshbuf_get_u32(m, &pid)) != 0)
1708 fatal("%s: decode PID: %s", __func__, ssh_err(r));
1709 sshbuf_free(m);
1710
1711 debug3("%s: done pid = %u", __func__, pid);
1712
1713 muxclient_request_id++;
1714
1715 return pid;
1716 }
1717
1718 static void
mux_client_request_terminate(int fd)1719 mux_client_request_terminate(int fd)
1720 {
1721 struct sshbuf *m;
1722 char *e;
1723 u_int type, rid;
1724 int r;
1725
1726 debug3("%s: entering", __func__);
1727
1728 if ((m = sshbuf_new()) == NULL)
1729 fatal("%s: sshbuf_new", __func__);
1730 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 ||
1731 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1732 fatal("%s: request: %s", __func__, ssh_err(r));
1733
1734 if (mux_client_write_packet(fd, m) != 0)
1735 fatal("%s: write packet: %s", __func__, strerror(errno));
1736
1737 sshbuf_reset(m);
1738
1739 /* Read their reply */
1740 if (mux_client_read_packet(fd, m) != 0) {
1741 /* Remote end exited already */
1742 if (errno == EPIPE) {
1743 sshbuf_free(m);
1744 return;
1745 }
1746 fatal("%s: read from master failed: %s",
1747 __func__, strerror(errno));
1748 }
1749
1750 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1751 (r = sshbuf_get_u32(m, &rid)) != 0)
1752 fatal("%s: decode: %s", __func__, ssh_err(r));
1753 if (rid != muxclient_request_id)
1754 fatal("%s: out of sequence reply: my id %u theirs %u",
1755 __func__, muxclient_request_id, rid);
1756 switch (type) {
1757 case MUX_S_OK:
1758 break;
1759 case MUX_S_PERMISSION_DENIED:
1760 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1761 fatal("%s: decode error: %s", __func__, ssh_err(r));
1762 fatal("Master refused termination request: %s", e);
1763 case MUX_S_FAILURE:
1764 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1765 fatal("%s: decode error: %s", __func__, ssh_err(r));
1766 fatal("%s: termination request failed: %s", __func__, e);
1767 default:
1768 fatal("%s: unexpected response from master 0x%08x",
1769 __func__, type);
1770 }
1771 sshbuf_free(m);
1772 muxclient_request_id++;
1773 }
1774
1775 static int
mux_client_forward(int fd,int cancel_flag,u_int ftype,struct Forward * fwd)1776 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd)
1777 {
1778 struct sshbuf *m;
1779 char *e, *fwd_desc;
1780 const char *lhost, *chost;
1781 u_int type, rid;
1782 int r;
1783
1784 fwd_desc = format_forward(ftype, fwd);
1785 debug("Requesting %s %s",
1786 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc);
1787 free(fwd_desc);
1788
1789 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD;
1790 if (fwd->listen_path != NULL)
1791 lhost = fwd->listen_path;
1792 else if (fwd->listen_host == NULL)
1793 lhost = "";
1794 else if (*fwd->listen_host == '\0')
1795 lhost = "*";
1796 else
1797 lhost = fwd->listen_host;
1798
1799 if (fwd->connect_path != NULL)
1800 chost = fwd->connect_path;
1801 else if (fwd->connect_host == NULL)
1802 chost = "";
1803 else
1804 chost = fwd->connect_host;
1805
1806 if ((m = sshbuf_new()) == NULL)
1807 fatal("%s: sshbuf_new", __func__);
1808 if ((r = sshbuf_put_u32(m, type)) != 0 ||
1809 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1810 (r = sshbuf_put_u32(m, ftype)) != 0 ||
1811 (r = sshbuf_put_cstring(m, lhost)) != 0 ||
1812 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 ||
1813 (r = sshbuf_put_cstring(m, chost)) != 0 ||
1814 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0)
1815 fatal("%s: request: %s", __func__, ssh_err(r));
1816
1817 if (mux_client_write_packet(fd, m) != 0)
1818 fatal("%s: write packet: %s", __func__, strerror(errno));
1819
1820 sshbuf_reset(m);
1821
1822 /* Read their reply */
1823 if (mux_client_read_packet(fd, m) != 0) {
1824 sshbuf_free(m);
1825 return -1;
1826 }
1827
1828 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1829 (r = sshbuf_get_u32(m, &rid)) != 0)
1830 fatal("%s: decode: %s", __func__, ssh_err(r));
1831 if (rid != muxclient_request_id)
1832 fatal("%s: out of sequence reply: my id %u theirs %u",
1833 __func__, muxclient_request_id, rid);
1834
1835 switch (type) {
1836 case MUX_S_OK:
1837 break;
1838 case MUX_S_REMOTE_PORT:
1839 if (cancel_flag)
1840 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__);
1841 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0)
1842 fatal("%s: decode port: %s", __func__, ssh_err(r));
1843 verbose("Allocated port %u for remote forward to %s:%d",
1844 fwd->allocated_port,
1845 fwd->connect_host ? fwd->connect_host : "",
1846 fwd->connect_port);
1847 if (muxclient_command == SSHMUX_COMMAND_FORWARD)
1848 fprintf(stdout, "%i\n", fwd->allocated_port);
1849 break;
1850 case MUX_S_PERMISSION_DENIED:
1851 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1852 fatal("%s: decode error: %s", __func__, ssh_err(r));
1853 sshbuf_free(m);
1854 error("Master refused forwarding request: %s", e);
1855 return -1;
1856 case MUX_S_FAILURE:
1857 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1858 fatal("%s: decode error: %s", __func__, ssh_err(r));
1859 sshbuf_free(m);
1860 error("%s: forwarding request failed: %s", __func__, e);
1861 return -1;
1862 default:
1863 fatal("%s: unexpected response from master 0x%08x",
1864 __func__, type);
1865 }
1866 sshbuf_free(m);
1867
1868 muxclient_request_id++;
1869 return 0;
1870 }
1871
1872 static int
mux_client_forwards(int fd,int cancel_flag)1873 mux_client_forwards(int fd, int cancel_flag)
1874 {
1875 int i, ret = 0;
1876
1877 debug3("%s: %s forwardings: %d local, %d remote", __func__,
1878 cancel_flag ? "cancel" : "request",
1879 options.num_local_forwards, options.num_remote_forwards);
1880
1881 /* XXX ExitOnForwardingFailure */
1882 for (i = 0; i < options.num_local_forwards; i++) {
1883 if (mux_client_forward(fd, cancel_flag,
1884 options.local_forwards[i].connect_port == 0 ?
1885 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1886 options.local_forwards + i) != 0)
1887 ret = -1;
1888 }
1889 for (i = 0; i < options.num_remote_forwards; i++) {
1890 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE,
1891 options.remote_forwards + i) != 0)
1892 ret = -1;
1893 }
1894 return ret;
1895 }
1896
1897 static int
mux_client_request_session(int fd)1898 mux_client_request_session(int fd)
1899 {
1900 struct sshbuf *m;
1901 char *e;
1902 const char *term;
1903 u_int echar, rid, sid, esid, exitval, type, exitval_seen;
1904 extern char **environ;
1905 int r, i, devnull, rawmode;
1906
1907 debug3("%s: entering", __func__);
1908
1909 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1910 error("%s: master alive request failed", __func__);
1911 return -1;
1912 }
1913
1914 ssh_signal(SIGPIPE, SIG_IGN);
1915
1916 if (stdin_null_flag) {
1917 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1918 fatal("open(/dev/null): %s", strerror(errno));
1919 if (dup2(devnull, STDIN_FILENO) == -1)
1920 fatal("dup2: %s", strerror(errno));
1921 if (devnull > STDERR_FILENO)
1922 close(devnull);
1923 }
1924
1925 if ((term = getenv("TERM")) == NULL)
1926 term = "";
1927 echar = 0xffffffff;
1928 if (options.escape_char != SSH_ESCAPECHAR_NONE)
1929 echar = (u_int)options.escape_char;
1930
1931 if ((m = sshbuf_new()) == NULL)
1932 fatal("%s: sshbuf_new", __func__);
1933 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 ||
1934 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1935 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
1936 (r = sshbuf_put_u32(m, tty_flag)) != 0 ||
1937 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 ||
1938 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 ||
1939 (r = sshbuf_put_u32(m, subsystem_flag)) != 0 ||
1940 (r = sshbuf_put_u32(m, echar)) != 0 ||
1941 (r = sshbuf_put_cstring(m, term)) != 0 ||
1942 (r = sshbuf_put_stringb(m, command)) != 0)
1943 fatal("%s: request: %s", __func__, ssh_err(r));
1944
1945 /* Pass environment */
1946 if (options.num_send_env > 0 && environ != NULL) {
1947 for (i = 0; environ[i] != NULL; i++) {
1948 if (!env_permitted(environ[i]))
1949 continue;
1950 if ((r = sshbuf_put_cstring(m, environ[i])) != 0)
1951 fatal("%s: request: %s", __func__, ssh_err(r));
1952 }
1953 }
1954 for (i = 0; i < options.num_setenv; i++) {
1955 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0)
1956 fatal("%s: request: %s", __func__, ssh_err(r));
1957 }
1958
1959 if (mux_client_write_packet(fd, m) != 0)
1960 fatal("%s: write packet: %s", __func__, strerror(errno));
1961
1962 /* Send the stdio file descriptors */
1963 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1964 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1965 mm_send_fd(fd, STDERR_FILENO) == -1)
1966 fatal("%s: send fds failed", __func__);
1967
1968 debug3("%s: session request sent", __func__);
1969
1970 /* Read their reply */
1971 sshbuf_reset(m);
1972 if (mux_client_read_packet(fd, m) != 0) {
1973 error("%s: read from master failed: %s",
1974 __func__, strerror(errno));
1975 sshbuf_free(m);
1976 return -1;
1977 }
1978
1979 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1980 (r = sshbuf_get_u32(m, &rid)) != 0)
1981 fatal("%s: decode: %s", __func__, ssh_err(r));
1982 if (rid != muxclient_request_id)
1983 fatal("%s: out of sequence reply: my id %u theirs %u",
1984 __func__, muxclient_request_id, rid);
1985
1986 switch (type) {
1987 case MUX_S_SESSION_OPENED:
1988 if ((r = sshbuf_get_u32(m, &sid)) != 0)
1989 fatal("%s: decode ID: %s", __func__, ssh_err(r));
1990 debug("%s: master session id: %u", __func__, sid);
1991 break;
1992 case MUX_S_PERMISSION_DENIED:
1993 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1994 fatal("%s: decode error: %s", __func__, ssh_err(r));
1995 error("Master refused session request: %s", e);
1996 sshbuf_free(m);
1997 return -1;
1998 case MUX_S_FAILURE:
1999 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2000 fatal("%s: decode error: %s", __func__, ssh_err(r));
2001 error("%s: session request failed: %s", __func__, e);
2002 sshbuf_free(m);
2003 return -1;
2004 default:
2005 sshbuf_free(m);
2006 error("%s: unexpected response from master 0x%08x",
2007 __func__, type);
2008 return -1;
2009 }
2010 muxclient_request_id++;
2011
2012 if (pledge("stdio proc tty", NULL) == -1)
2013 fatal("%s pledge(): %s", __func__, strerror(errno));
2014 platform_pledge_mux();
2015
2016 ssh_signal(SIGHUP, control_client_sighandler);
2017 ssh_signal(SIGINT, control_client_sighandler);
2018 ssh_signal(SIGTERM, control_client_sighandler);
2019 ssh_signal(SIGWINCH, control_client_sigrelay);
2020
2021 rawmode = tty_flag;
2022 if (tty_flag)
2023 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2024
2025 /*
2026 * Stick around until the controlee closes the client_fd.
2027 * Before it does, it is expected to write an exit message.
2028 * This process must read the value and wait for the closure of
2029 * the client_fd; if this one closes early, the multiplex master will
2030 * terminate early too (possibly losing data).
2031 */
2032 for (exitval = 255, exitval_seen = 0;;) {
2033 sshbuf_reset(m);
2034 if (mux_client_read_packet(fd, m) != 0)
2035 break;
2036 if ((r = sshbuf_get_u32(m, &type)) != 0)
2037 fatal("%s: decode type: %s", __func__, ssh_err(r));
2038 switch (type) {
2039 case MUX_S_TTY_ALLOC_FAIL:
2040 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2041 fatal("%s: decode ID: %s",
2042 __func__, ssh_err(r));
2043 if (esid != sid)
2044 fatal("%s: tty alloc fail on unknown session: "
2045 "my id %u theirs %u",
2046 __func__, sid, esid);
2047 leave_raw_mode(options.request_tty ==
2048 REQUEST_TTY_FORCE);
2049 rawmode = 0;
2050 continue;
2051 case MUX_S_EXIT_MESSAGE:
2052 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2053 fatal("%s: decode ID: %s",
2054 __func__, ssh_err(r));
2055 if (esid != sid)
2056 fatal("%s: exit on unknown session: "
2057 "my id %u theirs %u",
2058 __func__, sid, esid);
2059 if (exitval_seen)
2060 fatal("%s: exitval sent twice", __func__);
2061 if ((r = sshbuf_get_u32(m, &exitval)) != 0)
2062 fatal("%s: decode exit value: %s",
2063 __func__, ssh_err(r));
2064 exitval_seen = 1;
2065 continue;
2066 default:
2067 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2068 fatal("%s: decode error: %s",
2069 __func__, ssh_err(r));
2070 fatal("%s: master returned error: %s", __func__, e);
2071 }
2072 }
2073
2074 close(fd);
2075 if (rawmode)
2076 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2077
2078 if (muxclient_terminate) {
2079 debug2("Exiting on signal: %s", strsignal(muxclient_terminate));
2080 exitval = 255;
2081 } else if (!exitval_seen) {
2082 debug2("Control master terminated unexpectedly");
2083 exitval = 255;
2084 } else
2085 debug2("Received exit status from master %d", exitval);
2086
2087 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
2088 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
2089
2090 exit(exitval);
2091 }
2092
2093 static int
mux_client_proxy(int fd)2094 mux_client_proxy(int fd)
2095 {
2096 struct sshbuf *m;
2097 char *e;
2098 u_int type, rid;
2099 int r;
2100
2101 if ((m = sshbuf_new()) == NULL)
2102 fatal("%s: sshbuf_new", __func__);
2103 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 ||
2104 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2105 fatal("%s: request: %s", __func__, ssh_err(r));
2106 if (mux_client_write_packet(fd, m) != 0)
2107 fatal("%s: write packet: %s", __func__, strerror(errno));
2108
2109 sshbuf_reset(m);
2110
2111 /* Read their reply */
2112 if (mux_client_read_packet(fd, m) != 0) {
2113 sshbuf_free(m);
2114 return 0;
2115 }
2116 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2117 (r = sshbuf_get_u32(m, &rid)) != 0)
2118 fatal("%s: decode: %s", __func__, ssh_err(r));
2119 if (rid != muxclient_request_id)
2120 fatal("%s: out of sequence reply: my id %u theirs %u",
2121 __func__, muxclient_request_id, rid);
2122 if (type != MUX_S_PROXY) {
2123 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2124 fatal("%s: decode error: %s", __func__, ssh_err(r));
2125 fatal("%s: master returned error: %s", __func__, e);
2126 }
2127 sshbuf_free(m);
2128
2129 debug3("%s: done", __func__);
2130 muxclient_request_id++;
2131 return 0;
2132 }
2133
2134 static int
mux_client_request_stdio_fwd(int fd)2135 mux_client_request_stdio_fwd(int fd)
2136 {
2137 struct sshbuf *m;
2138 char *e;
2139 u_int type, rid, sid;
2140 int r, devnull;
2141
2142 debug3("%s: entering", __func__);
2143
2144 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
2145 error("%s: master alive request failed", __func__);
2146 return -1;
2147 }
2148
2149 ssh_signal(SIGPIPE, SIG_IGN);
2150
2151 if (stdin_null_flag) {
2152 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
2153 fatal("open(/dev/null): %s", strerror(errno));
2154 if (dup2(devnull, STDIN_FILENO) == -1)
2155 fatal("dup2: %s", strerror(errno));
2156 if (devnull > STDERR_FILENO)
2157 close(devnull);
2158 }
2159
2160 if ((m = sshbuf_new()) == NULL)
2161 fatal("%s: sshbuf_new", __func__);
2162 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 ||
2163 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
2164 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
2165 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 ||
2166 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0)
2167 fatal("%s: request: %s", __func__, ssh_err(r));
2168
2169 if (mux_client_write_packet(fd, m) != 0)
2170 fatal("%s: write packet: %s", __func__, strerror(errno));
2171
2172 /* Send the stdio file descriptors */
2173 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
2174 mm_send_fd(fd, STDOUT_FILENO) == -1)
2175 fatal("%s: send fds failed", __func__);
2176
2177 if (pledge("stdio proc tty", NULL) == -1)
2178 fatal("%s pledge(): %s", __func__, strerror(errno));
2179 platform_pledge_mux();
2180
2181 debug3("%s: stdio forward request sent", __func__);
2182
2183 /* Read their reply */
2184 sshbuf_reset(m);
2185
2186 if (mux_client_read_packet(fd, m) != 0) {
2187 error("%s: read from master failed: %s",
2188 __func__, strerror(errno));
2189 sshbuf_free(m);
2190 return -1;
2191 }
2192
2193 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2194 (r = sshbuf_get_u32(m, &rid)) != 0)
2195 fatal("%s: decode: %s", __func__, ssh_err(r));
2196 if (rid != muxclient_request_id)
2197 fatal("%s: out of sequence reply: my id %u theirs %u",
2198 __func__, muxclient_request_id, rid);
2199 switch (type) {
2200 case MUX_S_SESSION_OPENED:
2201 if ((r = sshbuf_get_u32(m, &sid)) != 0)
2202 fatal("%s: decode ID: %s", __func__, ssh_err(r));
2203 debug("%s: master session id: %u", __func__, sid);
2204 break;
2205 case MUX_S_PERMISSION_DENIED:
2206 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2207 fatal("%s: decode error: %s", __func__, ssh_err(r));
2208 sshbuf_free(m);
2209 fatal("Master refused stdio forwarding request: %s", e);
2210 case MUX_S_FAILURE:
2211 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2212 fatal("%s: decode error: %s", __func__, ssh_err(r));
2213 sshbuf_free(m);
2214 fatal("Stdio forwarding request failed: %s", e);
2215 default:
2216 sshbuf_free(m);
2217 error("%s: unexpected response from master 0x%08x",
2218 __func__, type);
2219 return -1;
2220 }
2221 muxclient_request_id++;
2222
2223 ssh_signal(SIGHUP, control_client_sighandler);
2224 ssh_signal(SIGINT, control_client_sighandler);
2225 ssh_signal(SIGTERM, control_client_sighandler);
2226 ssh_signal(SIGWINCH, control_client_sigrelay);
2227
2228 /*
2229 * Stick around until the controlee closes the client_fd.
2230 */
2231 sshbuf_reset(m);
2232 if (mux_client_read_packet(fd, m) != 0) {
2233 if (errno == EPIPE ||
2234 (errno == EINTR && muxclient_terminate != 0))
2235 return 0;
2236 fatal("%s: mux_client_read_packet: %s",
2237 __func__, strerror(errno));
2238 }
2239 fatal("%s: master returned unexpected message %u", __func__, type);
2240 }
2241
2242 static void
mux_client_request_stop_listening(int fd)2243 mux_client_request_stop_listening(int fd)
2244 {
2245 struct sshbuf *m;
2246 char *e;
2247 u_int type, rid;
2248 int r;
2249
2250 debug3("%s: entering", __func__);
2251
2252 if ((m = sshbuf_new()) == NULL)
2253 fatal("%s: sshbuf_new", __func__);
2254 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 ||
2255 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2256 fatal("%s: request: %s", __func__, ssh_err(r));
2257
2258 if (mux_client_write_packet(fd, m) != 0)
2259 fatal("%s: write packet: %s", __func__, strerror(errno));
2260
2261 sshbuf_reset(m);
2262
2263 /* Read their reply */
2264 if (mux_client_read_packet(fd, m) != 0)
2265 fatal("%s: read from master failed: %s",
2266 __func__, strerror(errno));
2267
2268 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2269 (r = sshbuf_get_u32(m, &rid)) != 0)
2270 fatal("%s: decode: %s", __func__, ssh_err(r));
2271 if (rid != muxclient_request_id)
2272 fatal("%s: out of sequence reply: my id %u theirs %u",
2273 __func__, muxclient_request_id, rid);
2274
2275 switch (type) {
2276 case MUX_S_OK:
2277 break;
2278 case MUX_S_PERMISSION_DENIED:
2279 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2280 fatal("%s: decode error: %s", __func__, ssh_err(r));
2281 fatal("Master refused stop listening request: %s", e);
2282 case MUX_S_FAILURE:
2283 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2284 fatal("%s: decode error: %s", __func__, ssh_err(r));
2285 fatal("%s: stop listening request failed: %s", __func__, e);
2286 default:
2287 fatal("%s: unexpected response from master 0x%08x",
2288 __func__, type);
2289 }
2290 sshbuf_free(m);
2291 muxclient_request_id++;
2292 }
2293
2294 /* Multiplex client main loop. */
2295 int
muxclient(const char * path)2296 muxclient(const char *path)
2297 {
2298 struct sockaddr_un addr;
2299 int sock;
2300 u_int pid;
2301
2302 if (muxclient_command == 0) {
2303 if (options.stdio_forward_host != NULL)
2304 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
2305 else
2306 muxclient_command = SSHMUX_COMMAND_OPEN;
2307 }
2308
2309 switch (options.control_master) {
2310 case SSHCTL_MASTER_AUTO:
2311 case SSHCTL_MASTER_AUTO_ASK:
2312 debug("auto-mux: Trying existing master");
2313 /* FALLTHROUGH */
2314 case SSHCTL_MASTER_NO:
2315 break;
2316 default:
2317 return -1;
2318 }
2319
2320 memset(&addr, '\0', sizeof(addr));
2321 addr.sun_family = AF_UNIX;
2322
2323 if (strlcpy(addr.sun_path, path,
2324 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
2325 fatal("ControlPath too long ('%s' >= %u bytes)", path,
2326 (unsigned int)sizeof(addr.sun_path));
2327
2328 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
2329 fatal("%s socket(): %s", __func__, strerror(errno));
2330
2331 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
2332 switch (muxclient_command) {
2333 case SSHMUX_COMMAND_OPEN:
2334 case SSHMUX_COMMAND_STDIO_FWD:
2335 break;
2336 default:
2337 fatal("Control socket connect(%.100s): %s", path,
2338 strerror(errno));
2339 }
2340 if (errno == ECONNREFUSED &&
2341 options.control_master != SSHCTL_MASTER_NO) {
2342 debug("Stale control socket %.100s, unlinking", path);
2343 unlink(path);
2344 } else if (errno == ENOENT) {
2345 debug("Control socket \"%.100s\" does not exist", path);
2346 } else {
2347 error("Control socket connect(%.100s): %s", path,
2348 strerror(errno));
2349 }
2350 close(sock);
2351 return -1;
2352 }
2353 set_nonblock(sock);
2354
2355 if (mux_client_hello_exchange(sock) != 0) {
2356 error("%s: master hello exchange failed", __func__);
2357 close(sock);
2358 return -1;
2359 }
2360
2361 switch (muxclient_command) {
2362 case SSHMUX_COMMAND_ALIVE_CHECK:
2363 if ((pid = mux_client_request_alive(sock)) == 0)
2364 fatal("%s: master alive check failed", __func__);
2365 fprintf(stderr, "Master running (pid=%u)\r\n", pid);
2366 exit(0);
2367 case SSHMUX_COMMAND_TERMINATE:
2368 mux_client_request_terminate(sock);
2369 if (options.log_level != SYSLOG_LEVEL_QUIET)
2370 fprintf(stderr, "Exit request sent.\r\n");
2371 exit(0);
2372 case SSHMUX_COMMAND_FORWARD:
2373 if (mux_client_forwards(sock, 0) != 0)
2374 fatal("%s: master forward request failed", __func__);
2375 exit(0);
2376 case SSHMUX_COMMAND_OPEN:
2377 if (mux_client_forwards(sock, 0) != 0) {
2378 error("%s: master forward request failed", __func__);
2379 return -1;
2380 }
2381 mux_client_request_session(sock);
2382 return -1;
2383 case SSHMUX_COMMAND_STDIO_FWD:
2384 mux_client_request_stdio_fwd(sock);
2385 exit(0);
2386 case SSHMUX_COMMAND_STOP:
2387 mux_client_request_stop_listening(sock);
2388 if (options.log_level != SYSLOG_LEVEL_QUIET)
2389 fprintf(stderr, "Stop listening request sent.\r\n");
2390 exit(0);
2391 case SSHMUX_COMMAND_CANCEL_FWD:
2392 if (mux_client_forwards(sock, 1) != 0)
2393 error("%s: master cancel forward request failed",
2394 __func__);
2395 exit(0);
2396 case SSHMUX_COMMAND_PROXY:
2397 mux_client_proxy(sock);
2398 return (sock);
2399 default:
2400 fatal("unrecognised muxclient_command %d", muxclient_command);
2401 }
2402 }
2403