1 /* $OpenBSD: mux.c,v 1.75 2018/07/31 03:07:24 djm Exp $ */
2 /*
3 * Copyright (c) 2002-2008 Damien Miller <[email protected]>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 /* ssh session multiplexing support */
19
20 /*
21 * TODO:
22 * - Better signalling from master to slave, especially passing of
23 * error messages
24 * - Better fall-back from mux slave error to new connection.
25 * - ExitOnForwardingFailure
26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding
27 * - Support ~^Z in mux slaves.
28 * - Inspect or control sessions in master.
29 * - If we ever support the "signal" channel request, send signals on
30 * sessions in master.
31 */
32
33 #include "includes.h"
34 __RCSID("$FreeBSD$");
35
36 #include <sys/types.h>
37 #include <sys/stat.h>
38 #include <sys/socket.h>
39 #include <sys/un.h>
40
41 #include <errno.h>
42 #include <fcntl.h>
43 #include <signal.h>
44 #include <stdarg.h>
45 #include <stddef.h>
46 #include <stdlib.h>
47 #include <stdio.h>
48 #include <string.h>
49 #include <unistd.h>
50 #ifdef HAVE_PATHS_H
51 #include <paths.h>
52 #endif
53
54 #ifdef HAVE_POLL_H
55 #include <poll.h>
56 #else
57 # ifdef HAVE_SYS_POLL_H
58 # include <sys/poll.h>
59 # endif
60 #endif
61
62 #ifdef HAVE_UTIL_H
63 # include <util.h>
64 #endif
65
66 #include "openbsd-compat/sys-queue.h"
67 #include "xmalloc.h"
68 #include "log.h"
69 #include "ssh.h"
70 #include "ssh2.h"
71 #include "pathnames.h"
72 #include "misc.h"
73 #include "match.h"
74 #include "sshbuf.h"
75 #include "channels.h"
76 #include "msg.h"
77 #include "packet.h"
78 #include "monitor_fdpass.h"
79 #include "sshpty.h"
80 #include "sshkey.h"
81 #include "readconf.h"
82 #include "clientloop.h"
83 #include "ssherr.h"
84
85 /* from ssh.c */
86 extern int tty_flag;
87 extern Options options;
88 extern int stdin_null_flag;
89 extern char *host;
90 extern int subsystem_flag;
91 extern struct sshbuf *command;
92 extern volatile sig_atomic_t quit_pending;
93
94 /* Context for session open confirmation callback */
95 struct mux_session_confirm_ctx {
96 u_int want_tty;
97 u_int want_subsys;
98 u_int want_x_fwd;
99 u_int want_agent_fwd;
100 struct sshbuf *cmd;
101 char *term;
102 struct termios tio;
103 char **env;
104 u_int rid;
105 };
106
107 /* Context for stdio fwd open confirmation callback */
108 struct mux_stdio_confirm_ctx {
109 u_int rid;
110 };
111
112 /* Context for global channel callback */
113 struct mux_channel_confirm_ctx {
114 u_int cid; /* channel id */
115 u_int rid; /* request id */
116 int fid; /* forward id */
117 };
118
119 /* fd to control socket */
120 int muxserver_sock = -1;
121
122 /* client request id */
123 u_int muxclient_request_id = 0;
124
125 /* Multiplexing control command */
126 u_int muxclient_command = 0;
127
128 /* Set when signalled. */
129 static volatile sig_atomic_t muxclient_terminate = 0;
130
131 /* PID of multiplex server */
132 static u_int muxserver_pid = 0;
133
134 static Channel *mux_listener_channel = NULL;
135
136 struct mux_master_state {
137 int hello_rcvd;
138 };
139
140 /* mux protocol messages */
141 #define MUX_MSG_HELLO 0x00000001
142 #define MUX_C_NEW_SESSION 0x10000002
143 #define MUX_C_ALIVE_CHECK 0x10000004
144 #define MUX_C_TERMINATE 0x10000005
145 #define MUX_C_OPEN_FWD 0x10000006
146 #define MUX_C_CLOSE_FWD 0x10000007
147 #define MUX_C_NEW_STDIO_FWD 0x10000008
148 #define MUX_C_STOP_LISTENING 0x10000009
149 #define MUX_C_PROXY 0x1000000f
150 #define MUX_S_OK 0x80000001
151 #define MUX_S_PERMISSION_DENIED 0x80000002
152 #define MUX_S_FAILURE 0x80000003
153 #define MUX_S_EXIT_MESSAGE 0x80000004
154 #define MUX_S_ALIVE 0x80000005
155 #define MUX_S_SESSION_OPENED 0x80000006
156 #define MUX_S_REMOTE_PORT 0x80000007
157 #define MUX_S_TTY_ALLOC_FAIL 0x80000008
158 #define MUX_S_PROXY 0x8000000f
159
160 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */
161 #define MUX_FWD_LOCAL 1
162 #define MUX_FWD_REMOTE 2
163 #define MUX_FWD_DYNAMIC 3
164
165 static void mux_session_confirm(struct ssh *, int, int, void *);
166 static void mux_stdio_confirm(struct ssh *, int, int, void *);
167
168 static int process_mux_master_hello(struct ssh *, u_int,
169 Channel *, struct sshbuf *, struct sshbuf *);
170 static int process_mux_new_session(struct ssh *, u_int,
171 Channel *, struct sshbuf *, struct sshbuf *);
172 static int process_mux_alive_check(struct ssh *, u_int,
173 Channel *, struct sshbuf *, struct sshbuf *);
174 static int process_mux_terminate(struct ssh *, u_int,
175 Channel *, struct sshbuf *, struct sshbuf *);
176 static int process_mux_open_fwd(struct ssh *, u_int,
177 Channel *, struct sshbuf *, struct sshbuf *);
178 static int process_mux_close_fwd(struct ssh *, u_int,
179 Channel *, struct sshbuf *, struct sshbuf *);
180 static int process_mux_stdio_fwd(struct ssh *, u_int,
181 Channel *, struct sshbuf *, struct sshbuf *);
182 static int process_mux_stop_listening(struct ssh *, u_int,
183 Channel *, struct sshbuf *, struct sshbuf *);
184 static int process_mux_proxy(struct ssh *, u_int,
185 Channel *, struct sshbuf *, struct sshbuf *);
186
187 static const struct {
188 u_int type;
189 int (*handler)(struct ssh *, u_int, Channel *,
190 struct sshbuf *, struct sshbuf *);
191 } mux_master_handlers[] = {
192 { MUX_MSG_HELLO, process_mux_master_hello },
193 { MUX_C_NEW_SESSION, process_mux_new_session },
194 { MUX_C_ALIVE_CHECK, process_mux_alive_check },
195 { MUX_C_TERMINATE, process_mux_terminate },
196 { MUX_C_OPEN_FWD, process_mux_open_fwd },
197 { MUX_C_CLOSE_FWD, process_mux_close_fwd },
198 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd },
199 { MUX_C_STOP_LISTENING, process_mux_stop_listening },
200 { MUX_C_PROXY, process_mux_proxy },
201 { 0, NULL }
202 };
203
204 /* Cleanup callback fired on closure of mux slave _session_ channel */
205 /* ARGSUSED */
206 static void
mux_master_session_cleanup_cb(struct ssh * ssh,int cid,void * unused)207 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused)
208 {
209 Channel *cc, *c = channel_by_id(ssh, cid);
210
211 debug3("%s: entering for channel %d", __func__, cid);
212 if (c == NULL)
213 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
214 if (c->ctl_chan != -1) {
215 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
216 fatal("%s: channel %d missing control channel %d",
217 __func__, c->self, c->ctl_chan);
218 c->ctl_chan = -1;
219 cc->remote_id = 0;
220 cc->have_remote_id = 0;
221 chan_rcvd_oclose(ssh, cc);
222 }
223 channel_cancel_cleanup(ssh, c->self);
224 }
225
226 /* Cleanup callback fired on closure of mux slave _control_ channel */
227 /* ARGSUSED */
228 static void
mux_master_control_cleanup_cb(struct ssh * ssh,int cid,void * unused)229 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused)
230 {
231 Channel *sc, *c = channel_by_id(ssh, cid);
232
233 debug3("%s: entering for channel %d", __func__, cid);
234 if (c == NULL)
235 fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
236 if (c->have_remote_id) {
237 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL)
238 fatal("%s: channel %d missing session channel %u",
239 __func__, c->self, c->remote_id);
240 c->remote_id = 0;
241 c->have_remote_id = 0;
242 sc->ctl_chan = -1;
243 if (sc->type != SSH_CHANNEL_OPEN &&
244 sc->type != SSH_CHANNEL_OPENING) {
245 debug2("%s: channel %d: not open", __func__, sc->self);
246 chan_mark_dead(ssh, sc);
247 } else {
248 if (sc->istate == CHAN_INPUT_OPEN)
249 chan_read_failed(ssh, sc);
250 if (sc->ostate == CHAN_OUTPUT_OPEN)
251 chan_write_failed(ssh, sc);
252 }
253 }
254 channel_cancel_cleanup(ssh, c->self);
255 }
256
257 /* Check mux client environment variables before passing them to mux master. */
258 static int
env_permitted(char * env)259 env_permitted(char *env)
260 {
261 int i, ret;
262 char name[1024], *cp;
263
264 if ((cp = strchr(env, '=')) == NULL || cp == env)
265 return 0;
266 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
267 if (ret <= 0 || (size_t)ret >= sizeof(name)) {
268 error("env_permitted: name '%.100s...' too long", env);
269 return 0;
270 }
271
272 for (i = 0; i < options.num_send_env; i++)
273 if (match_pattern(name, options.send_env[i]))
274 return 1;
275
276 return 0;
277 }
278
279 /* Mux master protocol message handlers */
280
281 static int
process_mux_master_hello(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)282 process_mux_master_hello(struct ssh *ssh, u_int rid,
283 Channel *c, struct sshbuf *m, struct sshbuf *reply)
284 {
285 u_int ver;
286 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
287 int r;
288
289 if (state == NULL)
290 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self);
291 if (state->hello_rcvd) {
292 error("%s: HELLO received twice", __func__);
293 return -1;
294 }
295 if ((r = sshbuf_get_u32(m, &ver)) != 0) {
296 error("%s: malformed message: %s", __func__, ssh_err(r));
297 return -1;
298 }
299 if (ver != SSHMUX_VER) {
300 error("Unsupported multiplexing protocol version %d "
301 "(expected %d)", ver, SSHMUX_VER);
302 return -1;
303 }
304 debug2("%s: channel %d slave version %u", __func__, c->self, ver);
305
306 /* No extensions are presently defined */
307 while (sshbuf_len(m) > 0) {
308 char *name = NULL;
309
310 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
311 (r = sshbuf_skip_string(m)) != 0) { /* value */
312 error("%s: malformed extension: %s",
313 __func__, ssh_err(r));
314 return -1;
315 }
316 debug2("Unrecognised slave extension \"%s\"", name);
317 free(name);
318 }
319 state->hello_rcvd = 1;
320 return 0;
321 }
322
323 /* Enqueue a "ok" response to the reply buffer */
324 static void
reply_ok(struct sshbuf * reply,u_int rid)325 reply_ok(struct sshbuf *reply, u_int rid)
326 {
327 int r;
328
329 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 ||
330 (r = sshbuf_put_u32(reply, rid)) != 0)
331 fatal("%s: reply: %s", __func__, ssh_err(r));
332 }
333
334 /* Enqueue an error response to the reply buffer */
335 static void
reply_error(struct sshbuf * reply,u_int type,u_int rid,const char * msg)336 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg)
337 {
338 int r;
339
340 if ((r = sshbuf_put_u32(reply, type)) != 0 ||
341 (r = sshbuf_put_u32(reply, rid)) != 0 ||
342 (r = sshbuf_put_cstring(reply, msg)) != 0)
343 fatal("%s: reply: %s", __func__, ssh_err(r));
344 }
345
346 static int
process_mux_new_session(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)347 process_mux_new_session(struct ssh *ssh, u_int rid,
348 Channel *c, struct sshbuf *m, struct sshbuf *reply)
349 {
350 Channel *nc;
351 struct mux_session_confirm_ctx *cctx;
352 char *cmd, *cp;
353 u_int i, j, env_len, escape_char, window, packetmax;
354 int r, new_fd[3];
355
356 /* Reply for SSHMUX_COMMAND_OPEN */
357 cctx = xcalloc(1, sizeof(*cctx));
358 cctx->term = NULL;
359 cctx->rid = rid;
360 cmd = NULL;
361 cctx->env = NULL;
362 env_len = 0;
363 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
364 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 ||
365 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 ||
366 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 ||
367 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 ||
368 (r = sshbuf_get_u32(m, &escape_char)) != 0 ||
369 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 ||
370 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) {
371 malf:
372 free(cmd);
373 for (j = 0; j < env_len; j++)
374 free(cctx->env[j]);
375 free(cctx->env);
376 free(cctx->term);
377 free(cctx);
378 error("%s: malformed message", __func__);
379 return -1;
380 }
381
382 #define MUX_MAX_ENV_VARS 4096
383 while (sshbuf_len(m) > 0) {
384 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0)
385 goto malf;
386 if (!env_permitted(cp)) {
387 free(cp);
388 continue;
389 }
390 cctx->env = xreallocarray(cctx->env, env_len + 2,
391 sizeof(*cctx->env));
392 cctx->env[env_len++] = cp;
393 cctx->env[env_len] = NULL;
394 if (env_len > MUX_MAX_ENV_VARS) {
395 error(">%d environment variables received, ignoring "
396 "additional", MUX_MAX_ENV_VARS);
397 break;
398 }
399 }
400
401 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, "
402 "term \"%s\", cmd \"%s\", env %u", __func__, c->self,
403 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd,
404 cctx->want_subsys, cctx->term, cmd, env_len);
405
406 if ((cctx->cmd = sshbuf_new()) == NULL)
407 fatal("%s: sshbuf_new", __func__);
408 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0)
409 fatal("%s: sshbuf_put: %s", __func__, ssh_err(r));
410 free(cmd);
411 cmd = NULL;
412
413 /* Gather fds from client */
414 for(i = 0; i < 3; i++) {
415 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
416 error("%s: failed to receive fd %d from slave",
417 __func__, i);
418 for (j = 0; j < i; j++)
419 close(new_fd[j]);
420 for (j = 0; j < env_len; j++)
421 free(cctx->env[j]);
422 free(cctx->env);
423 free(cctx->term);
424 sshbuf_free(cctx->cmd);
425 free(cctx);
426 reply_error(reply, MUX_S_FAILURE, rid,
427 "did not receive file descriptors");
428 return -1;
429 }
430 }
431
432 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
433 new_fd[0], new_fd[1], new_fd[2]);
434
435 /* XXX support multiple child sessions in future */
436 if (c->have_remote_id) {
437 debug2("%s: session already open", __func__);
438 reply_error(reply, MUX_S_FAILURE, rid,
439 "Multiple sessions not supported");
440 cleanup:
441 close(new_fd[0]);
442 close(new_fd[1]);
443 close(new_fd[2]);
444 free(cctx->term);
445 if (env_len != 0) {
446 for (i = 0; i < env_len; i++)
447 free(cctx->env[i]);
448 free(cctx->env);
449 }
450 sshbuf_free(cctx->cmd);
451 free(cctx);
452 return 0;
453 }
454
455 if (options.control_master == SSHCTL_MASTER_ASK ||
456 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
457 if (!ask_permission("Allow shared connection to %s? ", host)) {
458 debug2("%s: session refused by user", __func__);
459 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
460 "Permission denied");
461 goto cleanup;
462 }
463 }
464
465 /* Try to pick up ttymodes from client before it goes raw */
466 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
467 error("%s: tcgetattr: %s", __func__, strerror(errno));
468
469 /* enable nonblocking unless tty */
470 if (!isatty(new_fd[0]))
471 set_nonblock(new_fd[0]);
472 if (!isatty(new_fd[1]))
473 set_nonblock(new_fd[1]);
474 if (!isatty(new_fd[2]))
475 set_nonblock(new_fd[2]);
476
477 window = CHAN_SES_WINDOW_DEFAULT;
478 packetmax = CHAN_SES_PACKET_DEFAULT;
479 if (cctx->want_tty) {
480 window >>= 1;
481 packetmax >>= 1;
482 }
483
484 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
485 new_fd[0], new_fd[1], new_fd[2], window, packetmax,
486 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
487
488 nc->ctl_chan = c->self; /* link session -> control channel */
489 c->remote_id = nc->self; /* link control -> session channel */
490 c->have_remote_id = 1;
491
492 if (cctx->want_tty && escape_char != 0xffffffff) {
493 channel_register_filter(ssh, nc->self,
494 client_simple_escape_filter, NULL,
495 client_filter_cleanup,
496 client_new_escape_filter_ctx((int)escape_char));
497 }
498
499 debug2("%s: channel_new: %d linked to control channel %d",
500 __func__, nc->self, nc->ctl_chan);
501
502 channel_send_open(ssh, nc->self);
503 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx);
504 c->mux_pause = 1; /* stop handling messages until open_confirm done */
505 channel_register_cleanup(ssh, nc->self,
506 mux_master_session_cleanup_cb, 1);
507
508 /* reply is deferred, sent by mux_session_confirm */
509 return 0;
510 }
511
512 static int
process_mux_alive_check(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)513 process_mux_alive_check(struct ssh *ssh, u_int rid,
514 Channel *c, struct sshbuf *m, struct sshbuf *reply)
515 {
516 int r;
517
518 debug2("%s: channel %d: alive check", __func__, c->self);
519
520 /* prepare reply */
521 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 ||
522 (r = sshbuf_put_u32(reply, rid)) != 0 ||
523 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0)
524 fatal("%s: reply: %s", __func__, ssh_err(r));
525
526 return 0;
527 }
528
529 static int
process_mux_terminate(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)530 process_mux_terminate(struct ssh *ssh, u_int rid,
531 Channel *c, struct sshbuf *m, struct sshbuf *reply)
532 {
533 debug2("%s: channel %d: terminate request", __func__, c->self);
534
535 if (options.control_master == SSHCTL_MASTER_ASK ||
536 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
537 if (!ask_permission("Terminate shared connection to %s? ",
538 host)) {
539 debug2("%s: termination refused by user", __func__);
540 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
541 "Permission denied");
542 return 0;
543 }
544 }
545
546 quit_pending = 1;
547 reply_ok(reply, rid);
548 /* XXX exit happens too soon - message never makes it to client */
549 return 0;
550 }
551
552 static char *
format_forward(u_int ftype,struct Forward * fwd)553 format_forward(u_int ftype, struct Forward *fwd)
554 {
555 char *ret;
556
557 switch (ftype) {
558 case MUX_FWD_LOCAL:
559 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d",
560 (fwd->listen_path != NULL) ? fwd->listen_path :
561 (fwd->listen_host == NULL) ?
562 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
563 fwd->listen_host, fwd->listen_port,
564 (fwd->connect_path != NULL) ? fwd->connect_path :
565 fwd->connect_host, fwd->connect_port);
566 break;
567 case MUX_FWD_DYNAMIC:
568 xasprintf(&ret, "dynamic forward %.200s:%d -> *",
569 (fwd->listen_host == NULL) ?
570 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
571 fwd->listen_host, fwd->listen_port);
572 break;
573 case MUX_FWD_REMOTE:
574 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d",
575 (fwd->listen_path != NULL) ? fwd->listen_path :
576 (fwd->listen_host == NULL) ?
577 "LOCALHOST" : fwd->listen_host,
578 fwd->listen_port,
579 (fwd->connect_path != NULL) ? fwd->connect_path :
580 fwd->connect_host, fwd->connect_port);
581 break;
582 default:
583 fatal("%s: unknown forward type %u", __func__, ftype);
584 }
585 return ret;
586 }
587
588 static int
compare_host(const char * a,const char * b)589 compare_host(const char *a, const char *b)
590 {
591 if (a == NULL && b == NULL)
592 return 1;
593 if (a == NULL || b == NULL)
594 return 0;
595 return strcmp(a, b) == 0;
596 }
597
598 static int
compare_forward(struct Forward * a,struct Forward * b)599 compare_forward(struct Forward *a, struct Forward *b)
600 {
601 if (!compare_host(a->listen_host, b->listen_host))
602 return 0;
603 if (!compare_host(a->listen_path, b->listen_path))
604 return 0;
605 if (a->listen_port != b->listen_port)
606 return 0;
607 if (!compare_host(a->connect_host, b->connect_host))
608 return 0;
609 if (!compare_host(a->connect_path, b->connect_path))
610 return 0;
611 if (a->connect_port != b->connect_port)
612 return 0;
613
614 return 1;
615 }
616
617 static void
mux_confirm_remote_forward(struct ssh * ssh,int type,u_int32_t seq,void * ctxt)618 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
619 {
620 struct mux_channel_confirm_ctx *fctx = ctxt;
621 char *failmsg = NULL;
622 struct Forward *rfwd;
623 Channel *c;
624 struct sshbuf *out;
625 int r;
626
627 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) {
628 /* no channel for reply */
629 error("%s: unknown channel", __func__);
630 return;
631 }
632 if ((out = sshbuf_new()) == NULL)
633 fatal("%s: sshbuf_new", __func__);
634 if (fctx->fid >= options.num_remote_forwards ||
635 (options.remote_forwards[fctx->fid].connect_path == NULL &&
636 options.remote_forwards[fctx->fid].connect_host == NULL)) {
637 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid);
638 goto fail;
639 }
640 rfwd = &options.remote_forwards[fctx->fid];
641 debug("%s: %s for: listen %d, connect %s:%d", __func__,
642 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
643 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
644 rfwd->connect_host, rfwd->connect_port);
645 if (type == SSH2_MSG_REQUEST_SUCCESS) {
646 if (rfwd->listen_port == 0) {
647 rfwd->allocated_port = packet_get_int();
648 debug("Allocated port %u for mux remote forward"
649 " to %s:%d", rfwd->allocated_port,
650 rfwd->connect_host, rfwd->connect_port);
651 if ((r = sshbuf_put_u32(out,
652 MUX_S_REMOTE_PORT)) != 0 ||
653 (r = sshbuf_put_u32(out, fctx->rid)) != 0 ||
654 (r = sshbuf_put_u32(out,
655 rfwd->allocated_port)) != 0)
656 fatal("%s: reply: %s", __func__, ssh_err(r));
657 channel_update_permission(ssh, rfwd->handle,
658 rfwd->allocated_port);
659 } else {
660 reply_ok(out, fctx->rid);
661 }
662 goto out;
663 } else {
664 if (rfwd->listen_port == 0)
665 channel_update_permission(ssh, rfwd->handle, -1);
666 if (rfwd->listen_path != NULL)
667 xasprintf(&failmsg, "remote port forwarding failed for "
668 "listen path %s", rfwd->listen_path);
669 else
670 xasprintf(&failmsg, "remote port forwarding failed for "
671 "listen port %d", rfwd->listen_port);
672
673 debug2("%s: clearing registered forwarding for listen %d, "
674 "connect %s:%d", __func__, rfwd->listen_port,
675 rfwd->connect_path ? rfwd->connect_path :
676 rfwd->connect_host, rfwd->connect_port);
677
678 free(rfwd->listen_host);
679 free(rfwd->listen_path);
680 free(rfwd->connect_host);
681 free(rfwd->connect_path);
682 memset(rfwd, 0, sizeof(*rfwd));
683 }
684 fail:
685 error("%s: %s", __func__, failmsg);
686 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg);
687 free(failmsg);
688 out:
689 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
690 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
691 sshbuf_free(out);
692 if (c->mux_pause <= 0)
693 fatal("%s: mux_pause %d", __func__, c->mux_pause);
694 c->mux_pause = 0; /* start processing messages again */
695 }
696
697 static int
process_mux_open_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)698 process_mux_open_fwd(struct ssh *ssh, u_int rid,
699 Channel *c, struct sshbuf *m, struct sshbuf *reply)
700 {
701 struct Forward fwd;
702 char *fwd_desc = NULL;
703 char *listen_addr, *connect_addr;
704 u_int ftype;
705 u_int lport, cport;
706 int r, i, ret = 0, freefwd = 1;
707
708 memset(&fwd, 0, sizeof(fwd));
709
710 /* XXX - lport/cport check redundant */
711 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
712 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
713 (r = sshbuf_get_u32(m, &lport)) != 0 ||
714 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
715 (r = sshbuf_get_u32(m, &cport)) != 0 ||
716 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
717 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
718 error("%s: malformed message", __func__);
719 ret = -1;
720 goto out;
721 }
722 if (*listen_addr == '\0') {
723 free(listen_addr);
724 listen_addr = NULL;
725 }
726 if (*connect_addr == '\0') {
727 free(connect_addr);
728 connect_addr = NULL;
729 }
730
731 memset(&fwd, 0, sizeof(fwd));
732 fwd.listen_port = lport;
733 if (fwd.listen_port == PORT_STREAMLOCAL)
734 fwd.listen_path = listen_addr;
735 else
736 fwd.listen_host = listen_addr;
737 fwd.connect_port = cport;
738 if (fwd.connect_port == PORT_STREAMLOCAL)
739 fwd.connect_path = connect_addr;
740 else
741 fwd.connect_host = connect_addr;
742
743 debug2("%s: channel %d: request %s", __func__, c->self,
744 (fwd_desc = format_forward(ftype, &fwd)));
745
746 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE &&
747 ftype != MUX_FWD_DYNAMIC) {
748 logit("%s: invalid forwarding type %u", __func__, ftype);
749 invalid:
750 free(listen_addr);
751 free(connect_addr);
752 reply_error(reply, MUX_S_FAILURE, rid,
753 "Invalid forwarding request");
754 return 0;
755 }
756 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) {
757 logit("%s: streamlocal and dynamic forwards "
758 "are mutually exclusive", __func__);
759 goto invalid;
760 }
761 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) {
762 logit("%s: invalid listen port %u", __func__,
763 fwd.listen_port);
764 goto invalid;
765 }
766 if ((fwd.connect_port != PORT_STREAMLOCAL &&
767 fwd.connect_port >= 65536) ||
768 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE &&
769 fwd.connect_port == 0)) {
770 logit("%s: invalid connect port %u", __func__,
771 fwd.connect_port);
772 goto invalid;
773 }
774 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL &&
775 fwd.connect_path == NULL) {
776 logit("%s: missing connect host", __func__);
777 goto invalid;
778 }
779
780 /* Skip forwards that have already been requested */
781 switch (ftype) {
782 case MUX_FWD_LOCAL:
783 case MUX_FWD_DYNAMIC:
784 for (i = 0; i < options.num_local_forwards; i++) {
785 if (compare_forward(&fwd,
786 options.local_forwards + i)) {
787 exists:
788 debug2("%s: found existing forwarding",
789 __func__);
790 reply_ok(reply, rid);
791 goto out;
792 }
793 }
794 break;
795 case MUX_FWD_REMOTE:
796 for (i = 0; i < options.num_remote_forwards; i++) {
797 if (!compare_forward(&fwd, options.remote_forwards + i))
798 continue;
799 if (fwd.listen_port != 0)
800 goto exists;
801 debug2("%s: found allocated port", __func__);
802 if ((r = sshbuf_put_u32(reply,
803 MUX_S_REMOTE_PORT)) != 0 ||
804 (r = sshbuf_put_u32(reply, rid)) != 0 ||
805 (r = sshbuf_put_u32(reply,
806 options.remote_forwards[i].allocated_port)) != 0)
807 fatal("%s: reply: %s", __func__, ssh_err(r));
808 goto out;
809 }
810 break;
811 }
812
813 if (options.control_master == SSHCTL_MASTER_ASK ||
814 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
815 if (!ask_permission("Open %s on %s?", fwd_desc, host)) {
816 debug2("%s: forwarding refused by user", __func__);
817 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
818 "Permission denied");
819 goto out;
820 }
821 }
822
823 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
824 if (!channel_setup_local_fwd_listener(ssh, &fwd,
825 &options.fwd_opts)) {
826 fail:
827 logit("slave-requested %s failed", fwd_desc);
828 reply_error(reply, MUX_S_FAILURE, rid,
829 "Port forwarding failed");
830 goto out;
831 }
832 add_local_forward(&options, &fwd);
833 freefwd = 0;
834 } else {
835 struct mux_channel_confirm_ctx *fctx;
836
837 fwd.handle = channel_request_remote_forwarding(ssh, &fwd);
838 if (fwd.handle < 0)
839 goto fail;
840 add_remote_forward(&options, &fwd);
841 fctx = xcalloc(1, sizeof(*fctx));
842 fctx->cid = c->self;
843 fctx->rid = rid;
844 fctx->fid = options.num_remote_forwards - 1;
845 client_register_global_confirm(mux_confirm_remote_forward,
846 fctx);
847 freefwd = 0;
848 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */
849 /* delayed reply in mux_confirm_remote_forward */
850 goto out;
851 }
852 reply_ok(reply, rid);
853 out:
854 free(fwd_desc);
855 if (freefwd) {
856 free(fwd.listen_host);
857 free(fwd.listen_path);
858 free(fwd.connect_host);
859 free(fwd.connect_path);
860 }
861 return ret;
862 }
863
864 static int
process_mux_close_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)865 process_mux_close_fwd(struct ssh *ssh, u_int rid,
866 Channel *c, struct sshbuf *m, struct sshbuf *reply)
867 {
868 struct Forward fwd, *found_fwd;
869 char *fwd_desc = NULL;
870 const char *error_reason = NULL;
871 char *listen_addr = NULL, *connect_addr = NULL;
872 u_int ftype;
873 int r, i, ret = 0;
874 u_int lport, cport;
875
876 memset(&fwd, 0, sizeof(fwd));
877
878 if ((r = sshbuf_get_u32(m, &ftype)) != 0 ||
879 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 ||
880 (r = sshbuf_get_u32(m, &lport)) != 0 ||
881 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 ||
882 (r = sshbuf_get_u32(m, &cport)) != 0 ||
883 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) ||
884 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) {
885 error("%s: malformed message", __func__);
886 ret = -1;
887 goto out;
888 }
889
890 if (*listen_addr == '\0') {
891 free(listen_addr);
892 listen_addr = NULL;
893 }
894 if (*connect_addr == '\0') {
895 free(connect_addr);
896 connect_addr = NULL;
897 }
898
899 memset(&fwd, 0, sizeof(fwd));
900 fwd.listen_port = lport;
901 if (fwd.listen_port == PORT_STREAMLOCAL)
902 fwd.listen_path = listen_addr;
903 else
904 fwd.listen_host = listen_addr;
905 fwd.connect_port = cport;
906 if (fwd.connect_port == PORT_STREAMLOCAL)
907 fwd.connect_path = connect_addr;
908 else
909 fwd.connect_host = connect_addr;
910
911 debug2("%s: channel %d: request cancel %s", __func__, c->self,
912 (fwd_desc = format_forward(ftype, &fwd)));
913
914 /* make sure this has been requested */
915 found_fwd = NULL;
916 switch (ftype) {
917 case MUX_FWD_LOCAL:
918 case MUX_FWD_DYNAMIC:
919 for (i = 0; i < options.num_local_forwards; i++) {
920 if (compare_forward(&fwd,
921 options.local_forwards + i)) {
922 found_fwd = options.local_forwards + i;
923 break;
924 }
925 }
926 break;
927 case MUX_FWD_REMOTE:
928 for (i = 0; i < options.num_remote_forwards; i++) {
929 if (compare_forward(&fwd,
930 options.remote_forwards + i)) {
931 found_fwd = options.remote_forwards + i;
932 break;
933 }
934 }
935 break;
936 }
937
938 if (found_fwd == NULL)
939 error_reason = "port not forwarded";
940 else if (ftype == MUX_FWD_REMOTE) {
941 /*
942 * This shouldn't fail unless we confused the host/port
943 * between options.remote_forwards and permitted_opens.
944 * However, for dynamic allocated listen ports we need
945 * to use the actual listen port.
946 */
947 if (channel_request_rforward_cancel(ssh, found_fwd) == -1)
948 error_reason = "port not in permitted opens";
949 } else { /* local and dynamic forwards */
950 /* Ditto */
951 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port,
952 &options.fwd_opts) == -1)
953 error_reason = "port not found";
954 }
955
956 if (error_reason != NULL)
957 reply_error(reply, MUX_S_FAILURE, rid, error_reason);
958 else {
959 reply_ok(reply, rid);
960 free(found_fwd->listen_host);
961 free(found_fwd->listen_path);
962 free(found_fwd->connect_host);
963 free(found_fwd->connect_path);
964 found_fwd->listen_host = found_fwd->connect_host = NULL;
965 found_fwd->listen_path = found_fwd->connect_path = NULL;
966 found_fwd->listen_port = found_fwd->connect_port = 0;
967 }
968 out:
969 free(fwd_desc);
970 free(listen_addr);
971 free(connect_addr);
972
973 return ret;
974 }
975
976 static int
process_mux_stdio_fwd(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)977 process_mux_stdio_fwd(struct ssh *ssh, u_int rid,
978 Channel *c, struct sshbuf *m, struct sshbuf *reply)
979 {
980 Channel *nc;
981 char *chost = NULL;
982 u_int cport, i, j;
983 int r, new_fd[2];
984 struct mux_stdio_confirm_ctx *cctx;
985
986 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */
987 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
988 (r = sshbuf_get_u32(m, &cport)) != 0) {
989 free(chost);
990 error("%s: malformed message", __func__);
991 return -1;
992 }
993
994 debug2("%s: channel %d: request stdio fwd to %s:%u",
995 __func__, c->self, chost, cport);
996
997 /* Gather fds from client */
998 for(i = 0; i < 2; i++) {
999 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) {
1000 error("%s: failed to receive fd %d from slave",
1001 __func__, i);
1002 for (j = 0; j < i; j++)
1003 close(new_fd[j]);
1004 free(chost);
1005
1006 /* prepare reply */
1007 reply_error(reply, MUX_S_FAILURE, rid,
1008 "did not receive file descriptors");
1009 return -1;
1010 }
1011 }
1012
1013 debug3("%s: got fds stdin %d, stdout %d", __func__,
1014 new_fd[0], new_fd[1]);
1015
1016 /* XXX support multiple child sessions in future */
1017 if (c->have_remote_id) {
1018 debug2("%s: session already open", __func__);
1019 reply_error(reply, MUX_S_FAILURE, rid,
1020 "Multiple sessions not supported");
1021 cleanup:
1022 close(new_fd[0]);
1023 close(new_fd[1]);
1024 free(chost);
1025 return 0;
1026 }
1027
1028 if (options.control_master == SSHCTL_MASTER_ASK ||
1029 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1030 if (!ask_permission("Allow forward to %s:%u? ",
1031 chost, cport)) {
1032 debug2("%s: stdio fwd refused by user", __func__);
1033 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1034 "Permission denied");
1035 goto cleanup;
1036 }
1037 }
1038
1039 /* enable nonblocking unless tty */
1040 if (!isatty(new_fd[0]))
1041 set_nonblock(new_fd[0]);
1042 if (!isatty(new_fd[1]))
1043 set_nonblock(new_fd[1]);
1044
1045 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]);
1046 free(chost);
1047
1048 nc->ctl_chan = c->self; /* link session -> control channel */
1049 c->remote_id = nc->self; /* link control -> session channel */
1050 c->have_remote_id = 1;
1051
1052 debug2("%s: channel_new: %d linked to control channel %d",
1053 __func__, nc->self, nc->ctl_chan);
1054
1055 channel_register_cleanup(ssh, nc->self,
1056 mux_master_session_cleanup_cb, 1);
1057
1058 cctx = xcalloc(1, sizeof(*cctx));
1059 cctx->rid = rid;
1060 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx);
1061 c->mux_pause = 1; /* stop handling messages until open_confirm done */
1062
1063 /* reply is deferred, sent by mux_session_confirm */
1064 return 0;
1065 }
1066
1067 /* Callback on open confirmation in mux master for a mux stdio fwd session. */
1068 static void
mux_stdio_confirm(struct ssh * ssh,int id,int success,void * arg)1069 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1070 {
1071 struct mux_stdio_confirm_ctx *cctx = arg;
1072 Channel *c, *cc;
1073 struct sshbuf *reply;
1074 int r;
1075
1076 if (cctx == NULL)
1077 fatal("%s: cctx == NULL", __func__);
1078 if ((c = channel_by_id(ssh, id)) == NULL)
1079 fatal("%s: no channel for id %d", __func__, id);
1080 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1081 fatal("%s: channel %d lacks control channel %d", __func__,
1082 id, c->ctl_chan);
1083 if ((reply = sshbuf_new()) == NULL)
1084 fatal("%s: sshbuf_new", __func__);
1085
1086 if (!success) {
1087 debug3("%s: sending failure reply", __func__);
1088 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1089 "Session open refused by peer");
1090 /* prepare reply */
1091 goto done;
1092 }
1093
1094 debug3("%s: sending success reply", __func__);
1095 /* prepare reply */
1096 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1097 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1098 (r = sshbuf_put_u32(reply, c->self)) != 0)
1099 fatal("%s: reply: %s", __func__, ssh_err(r));
1100
1101 done:
1102 /* Send reply */
1103 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1104 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
1105 sshbuf_free(reply);
1106
1107 if (cc->mux_pause <= 0)
1108 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1109 cc->mux_pause = 0; /* start processing messages again */
1110 c->open_confirm_ctx = NULL;
1111 free(cctx);
1112 }
1113
1114 static int
process_mux_stop_listening(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1115 process_mux_stop_listening(struct ssh *ssh, u_int rid,
1116 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1117 {
1118 debug("%s: channel %d: stop listening", __func__, c->self);
1119
1120 if (options.control_master == SSHCTL_MASTER_ASK ||
1121 options.control_master == SSHCTL_MASTER_AUTO_ASK) {
1122 if (!ask_permission("Disable further multiplexing on shared "
1123 "connection to %s? ", host)) {
1124 debug2("%s: stop listen refused by user", __func__);
1125 reply_error(reply, MUX_S_PERMISSION_DENIED, rid,
1126 "Permission denied");
1127 return 0;
1128 }
1129 }
1130
1131 if (mux_listener_channel != NULL) {
1132 channel_free(ssh, mux_listener_channel);
1133 client_stop_mux();
1134 free(options.control_path);
1135 options.control_path = NULL;
1136 mux_listener_channel = NULL;
1137 muxserver_sock = -1;
1138 }
1139
1140 reply_ok(reply, rid);
1141 return 0;
1142 }
1143
1144 static int
process_mux_proxy(struct ssh * ssh,u_int rid,Channel * c,struct sshbuf * m,struct sshbuf * reply)1145 process_mux_proxy(struct ssh *ssh, u_int rid,
1146 Channel *c, struct sshbuf *m, struct sshbuf *reply)
1147 {
1148 int r;
1149
1150 debug("%s: channel %d: proxy request", __func__, c->self);
1151
1152 c->mux_rcb = channel_proxy_downstream;
1153 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 ||
1154 (r = sshbuf_put_u32(reply, rid)) != 0)
1155 fatal("%s: reply: %s", __func__, ssh_err(r));
1156
1157 return 0;
1158 }
1159
1160 /* Channel callbacks fired on read/write from mux slave fd */
1161 static int
mux_master_read_cb(struct ssh * ssh,Channel * c)1162 mux_master_read_cb(struct ssh *ssh, Channel *c)
1163 {
1164 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
1165 struct sshbuf *in = NULL, *out = NULL;
1166 u_int type, rid, i;
1167 int r, ret = -1;
1168
1169 if ((out = sshbuf_new()) == NULL)
1170 fatal("%s: sshbuf_new", __func__);
1171
1172 /* Setup ctx and */
1173 if (c->mux_ctx == NULL) {
1174 state = xcalloc(1, sizeof(*state));
1175 c->mux_ctx = state;
1176 channel_register_cleanup(ssh, c->self,
1177 mux_master_control_cleanup_cb, 0);
1178
1179 /* Send hello */
1180 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 ||
1181 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0)
1182 fatal("%s: reply: %s", __func__, ssh_err(r));
1183 /* no extensions */
1184 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
1185 fatal("%s: sshbuf_put_stringb: %s",
1186 __func__, ssh_err(r));
1187 debug3("%s: channel %d: hello sent", __func__, c->self);
1188 ret = 0;
1189 goto out;
1190 }
1191
1192 /* Channel code ensures that we receive whole packets */
1193 if ((r = sshbuf_froms(c->input, &in)) != 0) {
1194 malf:
1195 error("%s: malformed message", __func__);
1196 goto out;
1197 }
1198
1199 if ((r = sshbuf_get_u32(in, &type)) != 0)
1200 goto malf;
1201 debug3("%s: channel %d packet type 0x%08x len %zu",
1202 __func__, c->self, type, sshbuf_len(in));
1203
1204 if (type == MUX_MSG_HELLO)
1205 rid = 0;
1206 else {
1207 if (!state->hello_rcvd) {
1208 error("%s: expected MUX_MSG_HELLO(0x%08x), "
1209 "received 0x%08x", __func__, MUX_MSG_HELLO, type);
1210 goto out;
1211 }
1212 if ((r = sshbuf_get_u32(in, &rid)) != 0)
1213 goto malf;
1214 }
1215
1216 for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
1217 if (type == mux_master_handlers[i].type) {
1218 ret = mux_master_handlers[i].handler(ssh, rid,
1219 c, in, out);
1220 break;
1221 }
1222 }
1223 if (mux_master_handlers[i].handler == NULL) {
1224 error("%s: unsupported mux message 0x%08x", __func__, type);
1225 reply_error(out, MUX_S_FAILURE, rid, "unsupported request");
1226 ret = 0;
1227 }
1228 /* Enqueue reply packet */
1229 if (sshbuf_len(out) != 0) {
1230 if ((r = sshbuf_put_stringb(c->output, out)) != 0)
1231 fatal("%s: sshbuf_put_stringb: %s",
1232 __func__, ssh_err(r));
1233 }
1234 out:
1235 sshbuf_free(in);
1236 sshbuf_free(out);
1237 return ret;
1238 }
1239
1240 void
mux_exit_message(struct ssh * ssh,Channel * c,int exitval)1241 mux_exit_message(struct ssh *ssh, Channel *c, int exitval)
1242 {
1243 struct sshbuf *m;
1244 Channel *mux_chan;
1245 int r;
1246
1247 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self,
1248 exitval);
1249
1250 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1251 fatal("%s: channel %d missing mux channel %d",
1252 __func__, c->self, c->ctl_chan);
1253
1254 /* Append exit message packet to control socket output queue */
1255 if ((m = sshbuf_new()) == NULL)
1256 fatal("%s: sshbuf_new", __func__);
1257 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 ||
1258 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1259 (r = sshbuf_put_u32(m, exitval)) != 0 ||
1260 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1261 fatal("%s: reply: %s", __func__, ssh_err(r));
1262 sshbuf_free(m);
1263 }
1264
1265 void
mux_tty_alloc_failed(struct ssh * ssh,Channel * c)1266 mux_tty_alloc_failed(struct ssh *ssh, Channel *c)
1267 {
1268 struct sshbuf *m;
1269 Channel *mux_chan;
1270 int r;
1271
1272 debug3("%s: channel %d: TTY alloc failed", __func__, c->self);
1273
1274 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
1275 fatal("%s: channel %d missing mux channel %d",
1276 __func__, c->self, c->ctl_chan);
1277
1278 /* Append exit message packet to control socket output queue */
1279 if ((m = sshbuf_new()) == NULL)
1280 fatal("%s: sshbuf_new", __func__);
1281 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 ||
1282 (r = sshbuf_put_u32(m, c->self)) != 0 ||
1283 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0)
1284 fatal("%s: reply: %s", __func__, ssh_err(r));
1285 sshbuf_free(m);
1286 }
1287
1288 /* Prepare a mux master to listen on a Unix domain socket. */
1289 void
muxserver_listen(struct ssh * ssh)1290 muxserver_listen(struct ssh *ssh)
1291 {
1292 mode_t old_umask;
1293 char *orig_control_path = options.control_path;
1294 char rbuf[16+1];
1295 u_int i, r;
1296 int oerrno;
1297
1298 if (options.control_path == NULL ||
1299 options.control_master == SSHCTL_MASTER_NO)
1300 return;
1301
1302 debug("setting up multiplex master socket");
1303
1304 /*
1305 * Use a temporary path before listen so we can pseudo-atomically
1306 * establish the listening socket in its final location to avoid
1307 * other processes racing in between bind() and listen() and hitting
1308 * an unready socket.
1309 */
1310 for (i = 0; i < sizeof(rbuf) - 1; i++) {
1311 r = arc4random_uniform(26+26+10);
1312 rbuf[i] = (r < 26) ? 'a' + r :
1313 (r < 26*2) ? 'A' + r - 26 :
1314 '0' + r - 26 - 26;
1315 }
1316 rbuf[sizeof(rbuf) - 1] = '\0';
1317 options.control_path = NULL;
1318 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
1319 debug3("%s: temporary control path %s", __func__, options.control_path);
1320
1321 old_umask = umask(0177);
1322 muxserver_sock = unix_listener(options.control_path, 64, 0);
1323 oerrno = errno;
1324 umask(old_umask);
1325 if (muxserver_sock < 0) {
1326 if (oerrno == EINVAL || oerrno == EADDRINUSE) {
1327 error("ControlSocket %s already exists, "
1328 "disabling multiplexing", options.control_path);
1329 disable_mux_master:
1330 if (muxserver_sock != -1) {
1331 close(muxserver_sock);
1332 muxserver_sock = -1;
1333 }
1334 free(orig_control_path);
1335 free(options.control_path);
1336 options.control_path = NULL;
1337 options.control_master = SSHCTL_MASTER_NO;
1338 return;
1339 } else {
1340 /* unix_listener() logs the error */
1341 cleanup_exit(255);
1342 }
1343 }
1344
1345 /* Now atomically "move" the mux socket into position */
1346 if (link(options.control_path, orig_control_path) != 0) {
1347 if (errno != EEXIST) {
1348 fatal("%s: link mux listener %s => %s: %s", __func__,
1349 options.control_path, orig_control_path,
1350 strerror(errno));
1351 }
1352 error("ControlSocket %s already exists, disabling multiplexing",
1353 orig_control_path);
1354 unlink(options.control_path);
1355 goto disable_mux_master;
1356 }
1357 unlink(options.control_path);
1358 free(options.control_path);
1359 options.control_path = orig_control_path;
1360
1361 set_nonblock(muxserver_sock);
1362
1363 mux_listener_channel = channel_new(ssh, "mux listener",
1364 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
1365 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1366 0, options.control_path, 1);
1367 mux_listener_channel->mux_rcb = mux_master_read_cb;
1368 debug3("%s: mux listener channel %d fd %d", __func__,
1369 mux_listener_channel->self, mux_listener_channel->sock);
1370 }
1371
1372 /* Callback on open confirmation in mux master for a mux client session. */
1373 static void
mux_session_confirm(struct ssh * ssh,int id,int success,void * arg)1374 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg)
1375 {
1376 struct mux_session_confirm_ctx *cctx = arg;
1377 const char *display;
1378 Channel *c, *cc;
1379 int i, r;
1380 struct sshbuf *reply;
1381
1382 if (cctx == NULL)
1383 fatal("%s: cctx == NULL", __func__);
1384 if ((c = channel_by_id(ssh, id)) == NULL)
1385 fatal("%s: no channel for id %d", __func__, id);
1386 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
1387 fatal("%s: channel %d lacks control channel %d", __func__,
1388 id, c->ctl_chan);
1389 if ((reply = sshbuf_new()) == NULL)
1390 fatal("%s: sshbuf_new", __func__);
1391
1392 if (!success) {
1393 debug3("%s: sending failure reply", __func__);
1394 reply_error(reply, MUX_S_FAILURE, cctx->rid,
1395 "Session open refused by peer");
1396 goto done;
1397 }
1398
1399 display = getenv("DISPLAY");
1400 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
1401 char *proto, *data;
1402
1403 /* Get reasonable local authentication information. */
1404 if (client_x11_get_proto(ssh, display, options.xauth_location,
1405 options.forward_x11_trusted, options.forward_x11_timeout,
1406 &proto, &data) == 0) {
1407 /* Request forwarding with authentication spoofing. */
1408 debug("Requesting X11 forwarding with authentication "
1409 "spoofing.");
1410 x11_request_forwarding_with_spoofing(ssh, id,
1411 display, proto, data, 1);
1412 /* XXX exit_on_forward_failure */
1413 client_expect_confirm(ssh, id, "X11 forwarding",
1414 CONFIRM_WARN);
1415 }
1416 }
1417
1418 if (cctx->want_agent_fwd && options.forward_agent) {
1419 debug("Requesting authentication agent forwarding.");
1420 channel_request_start(ssh, id, "[email protected]", 0);
1421 packet_send();
1422 }
1423
1424 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys,
1425 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env);
1426
1427 debug3("%s: sending success reply", __func__);
1428 /* prepare reply */
1429 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 ||
1430 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 ||
1431 (r = sshbuf_put_u32(reply, c->self)) != 0)
1432 fatal("%s: reply: %s", __func__, ssh_err(r));
1433
1434 done:
1435 /* Send reply */
1436 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0)
1437 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
1438 sshbuf_free(reply);
1439
1440 if (cc->mux_pause <= 0)
1441 fatal("%s: mux_pause %d", __func__, cc->mux_pause);
1442 cc->mux_pause = 0; /* start processing messages again */
1443 c->open_confirm_ctx = NULL;
1444 sshbuf_free(cctx->cmd);
1445 free(cctx->term);
1446 if (cctx->env != NULL) {
1447 for (i = 0; cctx->env[i] != NULL; i++)
1448 free(cctx->env[i]);
1449 free(cctx->env);
1450 }
1451 free(cctx);
1452 }
1453
1454 /* ** Multiplexing client support */
1455
1456 /* Exit signal handler */
1457 static void
control_client_sighandler(int signo)1458 control_client_sighandler(int signo)
1459 {
1460 muxclient_terminate = signo;
1461 }
1462
1463 /*
1464 * Relay signal handler - used to pass some signals from mux client to
1465 * mux master.
1466 */
1467 static void
control_client_sigrelay(int signo)1468 control_client_sigrelay(int signo)
1469 {
1470 int save_errno = errno;
1471
1472 if (muxserver_pid > 1)
1473 kill(muxserver_pid, signo);
1474
1475 errno = save_errno;
1476 }
1477
1478 static int
mux_client_read(int fd,struct sshbuf * b,size_t need)1479 mux_client_read(int fd, struct sshbuf *b, size_t need)
1480 {
1481 size_t have;
1482 ssize_t len;
1483 u_char *p;
1484 struct pollfd pfd;
1485 int r;
1486
1487 pfd.fd = fd;
1488 pfd.events = POLLIN;
1489 if ((r = sshbuf_reserve(b, need, &p)) != 0)
1490 fatal("%s: reserve: %s", __func__, ssh_err(r));
1491 for (have = 0; have < need; ) {
1492 if (muxclient_terminate) {
1493 errno = EINTR;
1494 return -1;
1495 }
1496 len = read(fd, p + have, need - have);
1497 if (len < 0) {
1498 switch (errno) {
1499 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1500 case EWOULDBLOCK:
1501 #endif
1502 case EAGAIN:
1503 (void)poll(&pfd, 1, -1);
1504 /* FALLTHROUGH */
1505 case EINTR:
1506 continue;
1507 default:
1508 return -1;
1509 }
1510 }
1511 if (len == 0) {
1512 errno = EPIPE;
1513 return -1;
1514 }
1515 have += (size_t)len;
1516 }
1517 return 0;
1518 }
1519
1520 static int
mux_client_write_packet(int fd,struct sshbuf * m)1521 mux_client_write_packet(int fd, struct sshbuf *m)
1522 {
1523 struct sshbuf *queue;
1524 u_int have, need;
1525 int r, oerrno, len;
1526 const u_char *ptr;
1527 struct pollfd pfd;
1528
1529 pfd.fd = fd;
1530 pfd.events = POLLOUT;
1531 if ((queue = sshbuf_new()) == NULL)
1532 fatal("%s: sshbuf_new", __func__);
1533 if ((r = sshbuf_put_stringb(queue, m)) != 0)
1534 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r));
1535
1536 need = sshbuf_len(queue);
1537 ptr = sshbuf_ptr(queue);
1538
1539 for (have = 0; have < need; ) {
1540 if (muxclient_terminate) {
1541 sshbuf_free(queue);
1542 errno = EINTR;
1543 return -1;
1544 }
1545 len = write(fd, ptr + have, need - have);
1546 if (len < 0) {
1547 switch (errno) {
1548 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
1549 case EWOULDBLOCK:
1550 #endif
1551 case EAGAIN:
1552 (void)poll(&pfd, 1, -1);
1553 /* FALLTHROUGH */
1554 case EINTR:
1555 continue;
1556 default:
1557 oerrno = errno;
1558 sshbuf_free(queue);
1559 errno = oerrno;
1560 return -1;
1561 }
1562 }
1563 if (len == 0) {
1564 sshbuf_free(queue);
1565 errno = EPIPE;
1566 return -1;
1567 }
1568 have += (u_int)len;
1569 }
1570 sshbuf_free(queue);
1571 return 0;
1572 }
1573
1574 static int
mux_client_read_packet(int fd,struct sshbuf * m)1575 mux_client_read_packet(int fd, struct sshbuf *m)
1576 {
1577 struct sshbuf *queue;
1578 size_t need, have;
1579 const u_char *ptr;
1580 int r, oerrno;
1581
1582 if ((queue = sshbuf_new()) == NULL)
1583 fatal("%s: sshbuf_new", __func__);
1584 if (mux_client_read(fd, queue, 4) != 0) {
1585 if ((oerrno = errno) == EPIPE)
1586 debug3("%s: read header failed: %s", __func__,
1587 strerror(errno));
1588 sshbuf_free(queue);
1589 errno = oerrno;
1590 return -1;
1591 }
1592 need = PEEK_U32(sshbuf_ptr(queue));
1593 if (mux_client_read(fd, queue, need) != 0) {
1594 oerrno = errno;
1595 debug3("%s: read body failed: %s", __func__, strerror(errno));
1596 sshbuf_free(queue);
1597 errno = oerrno;
1598 return -1;
1599 }
1600 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 ||
1601 (r = sshbuf_put(m, ptr, have)) != 0)
1602 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1603 sshbuf_free(queue);
1604 return 0;
1605 }
1606
1607 static int
mux_client_hello_exchange(int fd)1608 mux_client_hello_exchange(int fd)
1609 {
1610 struct sshbuf *m;
1611 u_int type, ver;
1612 int r, ret = -1;
1613
1614 if ((m = sshbuf_new()) == NULL)
1615 fatal("%s: sshbuf_new", __func__);
1616 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 ||
1617 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0)
1618 fatal("%s: hello: %s", __func__, ssh_err(r));
1619 /* no extensions */
1620
1621 if (mux_client_write_packet(fd, m) != 0) {
1622 debug("%s: write packet: %s", __func__, strerror(errno));
1623 goto out;
1624 }
1625
1626 sshbuf_reset(m);
1627
1628 /* Read their HELLO */
1629 if (mux_client_read_packet(fd, m) != 0) {
1630 debug("%s: read packet failed", __func__);
1631 goto out;
1632 }
1633
1634 if ((r = sshbuf_get_u32(m, &type)) != 0)
1635 fatal("%s: decode type: %s", __func__, ssh_err(r));
1636 if (type != MUX_MSG_HELLO) {
1637 error("%s: expected HELLO (%u) received %u",
1638 __func__, MUX_MSG_HELLO, type);
1639 goto out;
1640 }
1641 if ((r = sshbuf_get_u32(m, &ver)) != 0)
1642 fatal("%s: decode version: %s", __func__, ssh_err(r));
1643 if (ver != SSHMUX_VER) {
1644 error("Unsupported multiplexing protocol version %d "
1645 "(expected %d)", ver, SSHMUX_VER);
1646 goto out;
1647 }
1648 debug2("%s: master version %u", __func__, ver);
1649 /* No extensions are presently defined */
1650 while (sshbuf_len(m) > 0) {
1651 char *name = NULL;
1652
1653 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 ||
1654 (r = sshbuf_skip_string(m)) != 0) { /* value */
1655 error("%s: malformed extension: %s",
1656 __func__, ssh_err(r));
1657 goto out;
1658 }
1659 debug2("Unrecognised master extension \"%s\"", name);
1660 free(name);
1661 }
1662 /* success */
1663 ret = 0;
1664 out:
1665 sshbuf_free(m);
1666 return ret;
1667 }
1668
1669 static u_int
mux_client_request_alive(int fd)1670 mux_client_request_alive(int fd)
1671 {
1672 struct sshbuf *m;
1673 char *e;
1674 u_int pid, type, rid;
1675 int r;
1676
1677 debug3("%s: entering", __func__);
1678
1679 if ((m = sshbuf_new()) == NULL)
1680 fatal("%s: sshbuf_new", __func__);
1681 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 ||
1682 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1683 fatal("%s: request: %s", __func__, ssh_err(r));
1684
1685 if (mux_client_write_packet(fd, m) != 0)
1686 fatal("%s: write packet: %s", __func__, strerror(errno));
1687
1688 sshbuf_reset(m);
1689
1690 /* Read their reply */
1691 if (mux_client_read_packet(fd, m) != 0) {
1692 sshbuf_free(m);
1693 return 0;
1694 }
1695
1696 if ((r = sshbuf_get_u32(m, &type)) != 0)
1697 fatal("%s: decode type: %s", __func__, ssh_err(r));
1698 if (type != MUX_S_ALIVE) {
1699 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1700 fatal("%s: decode error: %s", __func__, ssh_err(r));
1701 fatal("%s: master returned error: %s", __func__, e);
1702 }
1703
1704 if ((r = sshbuf_get_u32(m, &rid)) != 0)
1705 fatal("%s: decode remote ID: %s", __func__, ssh_err(r));
1706 if (rid != muxclient_request_id)
1707 fatal("%s: out of sequence reply: my id %u theirs %u",
1708 __func__, muxclient_request_id, rid);
1709 if ((r = sshbuf_get_u32(m, &pid)) != 0)
1710 fatal("%s: decode PID: %s", __func__, ssh_err(r));
1711 sshbuf_free(m);
1712
1713 debug3("%s: done pid = %u", __func__, pid);
1714
1715 muxclient_request_id++;
1716
1717 return pid;
1718 }
1719
1720 static void
mux_client_request_terminate(int fd)1721 mux_client_request_terminate(int fd)
1722 {
1723 struct sshbuf *m;
1724 char *e;
1725 u_int type, rid;
1726 int r;
1727
1728 debug3("%s: entering", __func__);
1729
1730 if ((m = sshbuf_new()) == NULL)
1731 fatal("%s: sshbuf_new", __func__);
1732 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 ||
1733 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
1734 fatal("%s: request: %s", __func__, ssh_err(r));
1735
1736 if (mux_client_write_packet(fd, m) != 0)
1737 fatal("%s: write packet: %s", __func__, strerror(errno));
1738
1739 sshbuf_reset(m);
1740
1741 /* Read their reply */
1742 if (mux_client_read_packet(fd, m) != 0) {
1743 /* Remote end exited already */
1744 if (errno == EPIPE) {
1745 sshbuf_free(m);
1746 return;
1747 }
1748 fatal("%s: read from master failed: %s",
1749 __func__, strerror(errno));
1750 }
1751
1752 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1753 (r = sshbuf_get_u32(m, &rid)) != 0)
1754 fatal("%s: decode: %s", __func__, ssh_err(r));
1755 if (rid != muxclient_request_id)
1756 fatal("%s: out of sequence reply: my id %u theirs %u",
1757 __func__, muxclient_request_id, rid);
1758 switch (type) {
1759 case MUX_S_OK:
1760 break;
1761 case MUX_S_PERMISSION_DENIED:
1762 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1763 fatal("%s: decode error: %s", __func__, ssh_err(r));
1764 fatal("Master refused termination request: %s", e);
1765 case MUX_S_FAILURE:
1766 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1767 fatal("%s: decode error: %s", __func__, ssh_err(r));
1768 fatal("%s: termination request failed: %s", __func__, e);
1769 default:
1770 fatal("%s: unexpected response from master 0x%08x",
1771 __func__, type);
1772 }
1773 sshbuf_free(m);
1774 muxclient_request_id++;
1775 }
1776
1777 static int
mux_client_forward(int fd,int cancel_flag,u_int ftype,struct Forward * fwd)1778 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd)
1779 {
1780 struct sshbuf *m;
1781 char *e, *fwd_desc;
1782 const char *lhost, *chost;
1783 u_int type, rid;
1784 int r;
1785
1786 fwd_desc = format_forward(ftype, fwd);
1787 debug("Requesting %s %s",
1788 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc);
1789 free(fwd_desc);
1790
1791 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD;
1792 if (fwd->listen_path != NULL)
1793 lhost = fwd->listen_path;
1794 else if (fwd->listen_host == NULL)
1795 lhost = "";
1796 else if (*fwd->listen_host == '\0')
1797 lhost = "*";
1798 else
1799 lhost = fwd->listen_host;
1800
1801 if (fwd->connect_path != NULL)
1802 chost = fwd->connect_path;
1803 else if (fwd->connect_host == NULL)
1804 chost = "";
1805 else
1806 chost = fwd->connect_host;
1807
1808 if ((m = sshbuf_new()) == NULL)
1809 fatal("%s: sshbuf_new", __func__);
1810 if ((r = sshbuf_put_u32(m, type)) != 0 ||
1811 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1812 (r = sshbuf_put_u32(m, ftype)) != 0 ||
1813 (r = sshbuf_put_cstring(m, lhost)) != 0 ||
1814 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 ||
1815 (r = sshbuf_put_cstring(m, chost)) != 0 ||
1816 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0)
1817 fatal("%s: request: %s", __func__, ssh_err(r));
1818
1819 if (mux_client_write_packet(fd, m) != 0)
1820 fatal("%s: write packet: %s", __func__, strerror(errno));
1821
1822 sshbuf_reset(m);
1823
1824 /* Read their reply */
1825 if (mux_client_read_packet(fd, m) != 0) {
1826 sshbuf_free(m);
1827 return -1;
1828 }
1829
1830 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1831 (r = sshbuf_get_u32(m, &rid)) != 0)
1832 fatal("%s: decode: %s", __func__, ssh_err(r));
1833 if (rid != muxclient_request_id)
1834 fatal("%s: out of sequence reply: my id %u theirs %u",
1835 __func__, muxclient_request_id, rid);
1836
1837 switch (type) {
1838 case MUX_S_OK:
1839 break;
1840 case MUX_S_REMOTE_PORT:
1841 if (cancel_flag)
1842 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__);
1843 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0)
1844 fatal("%s: decode port: %s", __func__, ssh_err(r));
1845 verbose("Allocated port %u for remote forward to %s:%d",
1846 fwd->allocated_port,
1847 fwd->connect_host ? fwd->connect_host : "",
1848 fwd->connect_port);
1849 if (muxclient_command == SSHMUX_COMMAND_FORWARD)
1850 fprintf(stdout, "%i\n", fwd->allocated_port);
1851 break;
1852 case MUX_S_PERMISSION_DENIED:
1853 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1854 fatal("%s: decode error: %s", __func__, ssh_err(r));
1855 sshbuf_free(m);
1856 error("Master refused forwarding request: %s", e);
1857 return -1;
1858 case MUX_S_FAILURE:
1859 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1860 fatal("%s: decode error: %s", __func__, ssh_err(r));
1861 sshbuf_free(m);
1862 error("%s: forwarding request failed: %s", __func__, e);
1863 return -1;
1864 default:
1865 fatal("%s: unexpected response from master 0x%08x",
1866 __func__, type);
1867 }
1868 sshbuf_free(m);
1869
1870 muxclient_request_id++;
1871 return 0;
1872 }
1873
1874 static int
mux_client_forwards(int fd,int cancel_flag)1875 mux_client_forwards(int fd, int cancel_flag)
1876 {
1877 int i, ret = 0;
1878
1879 debug3("%s: %s forwardings: %d local, %d remote", __func__,
1880 cancel_flag ? "cancel" : "request",
1881 options.num_local_forwards, options.num_remote_forwards);
1882
1883 /* XXX ExitOnForwardingFailure */
1884 for (i = 0; i < options.num_local_forwards; i++) {
1885 if (mux_client_forward(fd, cancel_flag,
1886 options.local_forwards[i].connect_port == 0 ?
1887 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL,
1888 options.local_forwards + i) != 0)
1889 ret = -1;
1890 }
1891 for (i = 0; i < options.num_remote_forwards; i++) {
1892 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE,
1893 options.remote_forwards + i) != 0)
1894 ret = -1;
1895 }
1896 return ret;
1897 }
1898
1899 static int
mux_client_request_session(int fd)1900 mux_client_request_session(int fd)
1901 {
1902 struct sshbuf *m;
1903 char *e;
1904 const char *term;
1905 u_int echar, rid, sid, esid, exitval, type, exitval_seen;
1906 extern char **environ;
1907 int r, i, devnull, rawmode;
1908
1909 debug3("%s: entering", __func__);
1910
1911 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
1912 error("%s: master alive request failed", __func__);
1913 return -1;
1914 }
1915
1916 signal(SIGPIPE, SIG_IGN);
1917
1918 if (stdin_null_flag) {
1919 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1920 fatal("open(/dev/null): %s", strerror(errno));
1921 if (dup2(devnull, STDIN_FILENO) == -1)
1922 fatal("dup2: %s", strerror(errno));
1923 if (devnull > STDERR_FILENO)
1924 close(devnull);
1925 }
1926
1927 if ((term = getenv("TERM")) == NULL)
1928 term = "";
1929 echar = 0xffffffff;
1930 if (options.escape_char != SSH_ESCAPECHAR_NONE)
1931 echar = (u_int)options.escape_char;
1932
1933 if ((m = sshbuf_new()) == NULL)
1934 fatal("%s: sshbuf_new", __func__);
1935 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 ||
1936 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
1937 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
1938 (r = sshbuf_put_u32(m, tty_flag)) != 0 ||
1939 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 ||
1940 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 ||
1941 (r = sshbuf_put_u32(m, subsystem_flag)) != 0 ||
1942 (r = sshbuf_put_u32(m, echar)) != 0 ||
1943 (r = sshbuf_put_cstring(m, term)) != 0 ||
1944 (r = sshbuf_put_stringb(m, command)) != 0)
1945 fatal("%s: request: %s", __func__, ssh_err(r));
1946
1947 /* Pass environment */
1948 if (options.num_send_env > 0 && environ != NULL) {
1949 for (i = 0; environ[i] != NULL; i++) {
1950 if (!env_permitted(environ[i]))
1951 continue;
1952 if ((r = sshbuf_put_cstring(m, environ[i])) != 0)
1953 fatal("%s: request: %s", __func__, ssh_err(r));
1954 }
1955 }
1956 for (i = 0; i < options.num_setenv; i++) {
1957 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0)
1958 fatal("%s: request: %s", __func__, ssh_err(r));
1959 }
1960
1961 if (mux_client_write_packet(fd, m) != 0)
1962 fatal("%s: write packet: %s", __func__, strerror(errno));
1963
1964 /* Send the stdio file descriptors */
1965 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
1966 mm_send_fd(fd, STDOUT_FILENO) == -1 ||
1967 mm_send_fd(fd, STDERR_FILENO) == -1)
1968 fatal("%s: send fds failed", __func__);
1969
1970 debug3("%s: session request sent", __func__);
1971
1972 /* Read their reply */
1973 sshbuf_reset(m);
1974 if (mux_client_read_packet(fd, m) != 0) {
1975 error("%s: read from master failed: %s",
1976 __func__, strerror(errno));
1977 sshbuf_free(m);
1978 return -1;
1979 }
1980
1981 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1982 (r = sshbuf_get_u32(m, &rid)) != 0)
1983 fatal("%s: decode: %s", __func__, ssh_err(r));
1984 if (rid != muxclient_request_id)
1985 fatal("%s: out of sequence reply: my id %u theirs %u",
1986 __func__, muxclient_request_id, rid);
1987
1988 switch (type) {
1989 case MUX_S_SESSION_OPENED:
1990 if ((r = sshbuf_get_u32(m, &sid)) != 0)
1991 fatal("%s: decode ID: %s", __func__, ssh_err(r));
1992 break;
1993 case MUX_S_PERMISSION_DENIED:
1994 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
1995 fatal("%s: decode error: %s", __func__, ssh_err(r));
1996 error("Master refused session request: %s", e);
1997 sshbuf_free(m);
1998 return -1;
1999 case MUX_S_FAILURE:
2000 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2001 fatal("%s: decode error: %s", __func__, ssh_err(r));
2002 error("%s: session request failed: %s", __func__, e);
2003 sshbuf_free(m);
2004 return -1;
2005 default:
2006 sshbuf_free(m);
2007 error("%s: unexpected response from master 0x%08x",
2008 __func__, type);
2009 return -1;
2010 }
2011 muxclient_request_id++;
2012
2013 if (pledge("stdio proc tty", NULL) == -1)
2014 fatal("%s pledge(): %s", __func__, strerror(errno));
2015 platform_pledge_mux();
2016
2017 signal(SIGHUP, control_client_sighandler);
2018 signal(SIGINT, control_client_sighandler);
2019 signal(SIGTERM, control_client_sighandler);
2020 signal(SIGWINCH, control_client_sigrelay);
2021
2022 rawmode = tty_flag;
2023 if (tty_flag)
2024 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2025
2026 /*
2027 * Stick around until the controlee closes the client_fd.
2028 * Before it does, it is expected to write an exit message.
2029 * This process must read the value and wait for the closure of
2030 * the client_fd; if this one closes early, the multiplex master will
2031 * terminate early too (possibly losing data).
2032 */
2033 for (exitval = 255, exitval_seen = 0;;) {
2034 sshbuf_reset(m);
2035 if (mux_client_read_packet(fd, m) != 0)
2036 break;
2037 if ((r = sshbuf_get_u32(m, &type)) != 0)
2038 fatal("%s: decode type: %s", __func__, ssh_err(r));
2039 switch (type) {
2040 case MUX_S_TTY_ALLOC_FAIL:
2041 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2042 fatal("%s: decode ID: %s",
2043 __func__, ssh_err(r));
2044 if (esid != sid)
2045 fatal("%s: tty alloc fail on unknown session: "
2046 "my id %u theirs %u",
2047 __func__, sid, esid);
2048 leave_raw_mode(options.request_tty ==
2049 REQUEST_TTY_FORCE);
2050 rawmode = 0;
2051 continue;
2052 case MUX_S_EXIT_MESSAGE:
2053 if ((r = sshbuf_get_u32(m, &esid)) != 0)
2054 fatal("%s: decode ID: %s",
2055 __func__, ssh_err(r));
2056 if (esid != sid)
2057 fatal("%s: exit on unknown session: "
2058 "my id %u theirs %u",
2059 __func__, sid, esid);
2060 if (exitval_seen)
2061 fatal("%s: exitval sent twice", __func__);
2062 if ((r = sshbuf_get_u32(m, &exitval)) != 0)
2063 fatal("%s: decode exit value: %s",
2064 __func__, ssh_err(r));
2065 exitval_seen = 1;
2066 continue;
2067 default:
2068 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2069 fatal("%s: decode error: %s",
2070 __func__, ssh_err(r));
2071 fatal("%s: master returned error: %s", __func__, e);
2072 }
2073 }
2074
2075 close(fd);
2076 if (rawmode)
2077 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2078
2079 if (muxclient_terminate) {
2080 debug2("Exiting on signal: %s", strsignal(muxclient_terminate));
2081 exitval = 255;
2082 } else if (!exitval_seen) {
2083 debug2("Control master terminated unexpectedly");
2084 exitval = 255;
2085 } else
2086 debug2("Received exit status from master %d", exitval);
2087
2088 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
2089 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
2090
2091 exit(exitval);
2092 }
2093
2094 static int
mux_client_proxy(int fd)2095 mux_client_proxy(int fd)
2096 {
2097 struct sshbuf *m;
2098 char *e;
2099 u_int type, rid;
2100 int r;
2101
2102 if ((m = sshbuf_new()) == NULL)
2103 fatal("%s: sshbuf_new", __func__);
2104 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 ||
2105 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2106 fatal("%s: request: %s", __func__, ssh_err(r));
2107 if (mux_client_write_packet(fd, m) != 0)
2108 fatal("%s: write packet: %s", __func__, strerror(errno));
2109
2110 sshbuf_reset(m);
2111
2112 /* Read their reply */
2113 if (mux_client_read_packet(fd, m) != 0) {
2114 sshbuf_free(m);
2115 return 0;
2116 }
2117 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2118 (r = sshbuf_get_u32(m, &rid)) != 0)
2119 fatal("%s: decode: %s", __func__, ssh_err(r));
2120 if (rid != muxclient_request_id)
2121 fatal("%s: out of sequence reply: my id %u theirs %u",
2122 __func__, muxclient_request_id, rid);
2123 if (type != MUX_S_PROXY) {
2124 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2125 fatal("%s: decode error: %s", __func__, ssh_err(r));
2126 fatal("%s: master returned error: %s", __func__, e);
2127 }
2128 sshbuf_free(m);
2129
2130 debug3("%s: done", __func__);
2131 muxclient_request_id++;
2132 return 0;
2133 }
2134
2135 static int
mux_client_request_stdio_fwd(int fd)2136 mux_client_request_stdio_fwd(int fd)
2137 {
2138 struct sshbuf *m;
2139 char *e;
2140 u_int type, rid, sid;
2141 int r, devnull;
2142
2143 debug3("%s: entering", __func__);
2144
2145 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) {
2146 error("%s: master alive request failed", __func__);
2147 return -1;
2148 }
2149
2150 signal(SIGPIPE, SIG_IGN);
2151
2152 if (stdin_null_flag) {
2153 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1)
2154 fatal("open(/dev/null): %s", strerror(errno));
2155 if (dup2(devnull, STDIN_FILENO) == -1)
2156 fatal("dup2: %s", strerror(errno));
2157 if (devnull > STDERR_FILENO)
2158 close(devnull);
2159 }
2160
2161 if ((m = sshbuf_new()) == NULL)
2162 fatal("%s: sshbuf_new", __func__);
2163 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 ||
2164 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 ||
2165 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */
2166 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 ||
2167 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0)
2168 fatal("%s: request: %s", __func__, ssh_err(r));
2169
2170 if (mux_client_write_packet(fd, m) != 0)
2171 fatal("%s: write packet: %s", __func__, strerror(errno));
2172
2173 /* Send the stdio file descriptors */
2174 if (mm_send_fd(fd, STDIN_FILENO) == -1 ||
2175 mm_send_fd(fd, STDOUT_FILENO) == -1)
2176 fatal("%s: send fds failed", __func__);
2177
2178 if (pledge("stdio proc tty", NULL) == -1)
2179 fatal("%s pledge(): %s", __func__, strerror(errno));
2180 platform_pledge_mux();
2181
2182 debug3("%s: stdio forward request sent", __func__);
2183
2184 /* Read their reply */
2185 sshbuf_reset(m);
2186
2187 if (mux_client_read_packet(fd, m) != 0) {
2188 error("%s: read from master failed: %s",
2189 __func__, strerror(errno));
2190 sshbuf_free(m);
2191 return -1;
2192 }
2193
2194 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2195 (r = sshbuf_get_u32(m, &rid)) != 0)
2196 fatal("%s: decode: %s", __func__, ssh_err(r));
2197 if (rid != muxclient_request_id)
2198 fatal("%s: out of sequence reply: my id %u theirs %u",
2199 __func__, muxclient_request_id, rid);
2200 switch (type) {
2201 case MUX_S_SESSION_OPENED:
2202 if ((r = sshbuf_get_u32(m, &sid)) != 0)
2203 fatal("%s: decode ID: %s", __func__, ssh_err(r));
2204 debug("%s: master session id: %u", __func__, sid);
2205 break;
2206 case MUX_S_PERMISSION_DENIED:
2207 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2208 fatal("%s: decode error: %s", __func__, ssh_err(r));
2209 sshbuf_free(m);
2210 fatal("Master refused stdio forwarding request: %s", e);
2211 case MUX_S_FAILURE:
2212 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2213 fatal("%s: decode error: %s", __func__, ssh_err(r));
2214 sshbuf_free(m);
2215 fatal("Stdio forwarding request failed: %s", e);
2216 default:
2217 sshbuf_free(m);
2218 error("%s: unexpected response from master 0x%08x",
2219 __func__, type);
2220 return -1;
2221 }
2222 muxclient_request_id++;
2223
2224 signal(SIGHUP, control_client_sighandler);
2225 signal(SIGINT, control_client_sighandler);
2226 signal(SIGTERM, control_client_sighandler);
2227 signal(SIGWINCH, control_client_sigrelay);
2228
2229 /*
2230 * Stick around until the controlee closes the client_fd.
2231 */
2232 sshbuf_reset(m);
2233 if (mux_client_read_packet(fd, m) != 0) {
2234 if (errno == EPIPE ||
2235 (errno == EINTR && muxclient_terminate != 0))
2236 return 0;
2237 fatal("%s: mux_client_read_packet: %s",
2238 __func__, strerror(errno));
2239 }
2240 fatal("%s: master returned unexpected message %u", __func__, type);
2241 }
2242
2243 static void
mux_client_request_stop_listening(int fd)2244 mux_client_request_stop_listening(int fd)
2245 {
2246 struct sshbuf *m;
2247 char *e;
2248 u_int type, rid;
2249 int r;
2250
2251 debug3("%s: entering", __func__);
2252
2253 if ((m = sshbuf_new()) == NULL)
2254 fatal("%s: sshbuf_new", __func__);
2255 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 ||
2256 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0)
2257 fatal("%s: request: %s", __func__, ssh_err(r));
2258
2259 if (mux_client_write_packet(fd, m) != 0)
2260 fatal("%s: write packet: %s", __func__, strerror(errno));
2261
2262 sshbuf_reset(m);
2263
2264 /* Read their reply */
2265 if (mux_client_read_packet(fd, m) != 0)
2266 fatal("%s: read from master failed: %s",
2267 __func__, strerror(errno));
2268
2269 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
2270 (r = sshbuf_get_u32(m, &rid)) != 0)
2271 fatal("%s: decode: %s", __func__, ssh_err(r));
2272 if (rid != muxclient_request_id)
2273 fatal("%s: out of sequence reply: my id %u theirs %u",
2274 __func__, muxclient_request_id, rid);
2275
2276 switch (type) {
2277 case MUX_S_OK:
2278 break;
2279 case MUX_S_PERMISSION_DENIED:
2280 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2281 fatal("%s: decode error: %s", __func__, ssh_err(r));
2282 fatal("Master refused stop listening request: %s", e);
2283 case MUX_S_FAILURE:
2284 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0)
2285 fatal("%s: decode error: %s", __func__, ssh_err(r));
2286 fatal("%s: stop listening request failed: %s", __func__, e);
2287 default:
2288 fatal("%s: unexpected response from master 0x%08x",
2289 __func__, type);
2290 }
2291 sshbuf_free(m);
2292 muxclient_request_id++;
2293 }
2294
2295 /* Multiplex client main loop. */
2296 int
muxclient(const char * path)2297 muxclient(const char *path)
2298 {
2299 struct sockaddr_un addr;
2300 int sock;
2301 u_int pid;
2302
2303 if (muxclient_command == 0) {
2304 if (options.stdio_forward_host != NULL)
2305 muxclient_command = SSHMUX_COMMAND_STDIO_FWD;
2306 else
2307 muxclient_command = SSHMUX_COMMAND_OPEN;
2308 }
2309
2310 switch (options.control_master) {
2311 case SSHCTL_MASTER_AUTO:
2312 case SSHCTL_MASTER_AUTO_ASK:
2313 debug("auto-mux: Trying existing master");
2314 /* FALLTHROUGH */
2315 case SSHCTL_MASTER_NO:
2316 break;
2317 default:
2318 return -1;
2319 }
2320
2321 memset(&addr, '\0', sizeof(addr));
2322 addr.sun_family = AF_UNIX;
2323
2324 if (strlcpy(addr.sun_path, path,
2325 sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
2326 fatal("ControlPath too long ('%s' >= %u bytes)", path,
2327 (unsigned int)sizeof(addr.sun_path));
2328
2329 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
2330 fatal("%s socket(): %s", __func__, strerror(errno));
2331
2332 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
2333 switch (muxclient_command) {
2334 case SSHMUX_COMMAND_OPEN:
2335 case SSHMUX_COMMAND_STDIO_FWD:
2336 break;
2337 default:
2338 fatal("Control socket connect(%.100s): %s", path,
2339 strerror(errno));
2340 }
2341 if (errno == ECONNREFUSED &&
2342 options.control_master != SSHCTL_MASTER_NO) {
2343 debug("Stale control socket %.100s, unlinking", path);
2344 unlink(path);
2345 } else if (errno == ENOENT) {
2346 debug("Control socket \"%.100s\" does not exist", path);
2347 } else {
2348 error("Control socket connect(%.100s): %s", path,
2349 strerror(errno));
2350 }
2351 close(sock);
2352 return -1;
2353 }
2354 set_nonblock(sock);
2355
2356 if (mux_client_hello_exchange(sock) != 0) {
2357 error("%s: master hello exchange failed", __func__);
2358 close(sock);
2359 return -1;
2360 }
2361
2362 switch (muxclient_command) {
2363 case SSHMUX_COMMAND_ALIVE_CHECK:
2364 if ((pid = mux_client_request_alive(sock)) == 0)
2365 fatal("%s: master alive check failed", __func__);
2366 fprintf(stderr, "Master running (pid=%u)\r\n", pid);
2367 exit(0);
2368 case SSHMUX_COMMAND_TERMINATE:
2369 mux_client_request_terminate(sock);
2370 if (options.log_level != SYSLOG_LEVEL_QUIET)
2371 fprintf(stderr, "Exit request sent.\r\n");
2372 exit(0);
2373 case SSHMUX_COMMAND_FORWARD:
2374 if (mux_client_forwards(sock, 0) != 0)
2375 fatal("%s: master forward request failed", __func__);
2376 exit(0);
2377 case SSHMUX_COMMAND_OPEN:
2378 if (mux_client_forwards(sock, 0) != 0) {
2379 error("%s: master forward request failed", __func__);
2380 return -1;
2381 }
2382 mux_client_request_session(sock);
2383 return -1;
2384 case SSHMUX_COMMAND_STDIO_FWD:
2385 mux_client_request_stdio_fwd(sock);
2386 exit(0);
2387 case SSHMUX_COMMAND_STOP:
2388 mux_client_request_stop_listening(sock);
2389 if (options.log_level != SYSLOG_LEVEL_QUIET)
2390 fprintf(stderr, "Stop listening request sent.\r\n");
2391 exit(0);
2392 case SSHMUX_COMMAND_CANCEL_FWD:
2393 if (mux_client_forwards(sock, 1) != 0)
2394 error("%s: master cancel forward request failed",
2395 __func__);
2396 exit(0);
2397 case SSHMUX_COMMAND_PROXY:
2398 mux_client_proxy(sock);
2399 return (sock);
2400 default:
2401 fatal("unrecognised muxclient_command %d", muxclient_command);
2402 }
2403 }
2404