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1 | /* $OpenBSD: mux.c,v 1.7 2008/06/13 17:21:20 dtucker Exp $ */ | |
2 | /* | |
3 | * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> | |
4 | * | |
5 | * Permission to use, copy, modify, and distribute this software for any | |
6 | * purpose with or without fee is hereby granted, provided that the above | |
7 | * copyright notice and this permission notice appear in all copies. | |
8 | * | |
9 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES | |
10 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF | |
11 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR | |
12 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES | |
13 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN | |
14 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF | |
15 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. | |
16 | */ | |
17 | ||
18 | /* ssh session multiplexing support */ | |
19 | ||
20 | #include "includes.h" | |
21 | ||
22 | /* | |
23 | * TODO: | |
24 | * 1. partial reads in muxserver_accept_control (maybe make channels | |
25 | * from accepted connections) | |
26 | * 2. Better signalling from master to slave, especially passing of | |
27 | * error messages | |
28 | * 3. Better fall-back from mux slave error to new connection. | |
29 | * 3. Add/delete forwardings via slave | |
30 | * 4. ExitOnForwardingFailure (after #3 obviously) | |
31 | * 5. Maybe extension mechanisms for multi-X11/multi-agent forwarding | |
32 | * 6. Document the mux mini-protocol somewhere. | |
33 | * 7. Support ~^Z in mux slaves. | |
34 | * 8. Inspect or control sessions in master. | |
35 | * 9. If we ever support the "signal" channel request, send signals on | |
36 | * sessions in master. | |
37 | */ | |
38 | ||
39 | #include <sys/types.h> | |
40 | #include <sys/param.h> | |
41 | #include <sys/stat.h> | |
42 | #include <sys/socket.h> | |
43 | #include <sys/un.h> | |
44 | ||
45 | #include <errno.h> | |
46 | #include <fcntl.h> | |
47 | #include <signal.h> | |
48 | #include <stdarg.h> | |
49 | #include <stddef.h> | |
50 | #include <stdlib.h> | |
51 | #include <stdio.h> | |
52 | #include <string.h> | |
53 | #include <unistd.h> | |
54 | #ifdef HAVE_PATHS_H | |
55 | #include <paths.h> | |
56 | #endif | |
57 | ||
58 | #ifdef HAVE_UTIL_H | |
59 | # include <util.h> | |
60 | #endif | |
61 | ||
62 | #ifdef HAVE_LIBUTIL_H | |
63 | # include <libutil.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 "pathnames.h" | |
71 | #include "misc.h" | |
72 | #include "match.h" | |
73 | #include "buffer.h" | |
74 | #include "channels.h" | |
75 | #include "msg.h" | |
76 | #include "packet.h" | |
77 | #include "monitor_fdpass.h" | |
78 | #include "sshpty.h" | |
79 | #include "key.h" | |
80 | #include "readconf.h" | |
81 | #include "clientloop.h" | |
82 | ||
83 | /* from ssh.c */ | |
84 | extern int tty_flag; | |
85 | extern Options options; | |
86 | extern int stdin_null_flag; | |
87 | extern char *host; | |
88 | int subsystem_flag; | |
89 | extern Buffer command; | |
90 | ||
91 | /* Context for session open confirmation callback */ | |
92 | struct mux_session_confirm_ctx { | |
93 | int want_tty; | |
94 | int want_subsys; | |
95 | int want_x_fwd; | |
96 | int want_agent_fwd; | |
97 | Buffer cmd; | |
98 | char *term; | |
99 | struct termios tio; | |
100 | char **env; | |
101 | }; | |
102 | ||
103 | /* fd to control socket */ | |
104 | int muxserver_sock = -1; | |
105 | ||
106 | /* Multiplexing control command */ | |
107 | u_int muxclient_command = 0; | |
108 | ||
109 | /* Set when signalled. */ | |
110 | static volatile sig_atomic_t muxclient_terminate = 0; | |
111 | ||
112 | /* PID of multiplex server */ | |
113 | static u_int muxserver_pid = 0; | |
114 | ||
115 | ||
116 | /* ** Multiplexing master support */ | |
117 | ||
118 | /* Prepare a mux master to listen on a Unix domain socket. */ | |
119 | void | |
120 | muxserver_listen(void) | |
121 | { | |
122 | struct sockaddr_un addr; | |
123 | mode_t old_umask; | |
124 | int addr_len; | |
125 | ||
126 | if (options.control_path == NULL || | |
127 | options.control_master == SSHCTL_MASTER_NO) | |
128 | return; | |
129 | ||
130 | debug("setting up multiplex master socket"); | |
131 | ||
132 | memset(&addr, '\0', sizeof(addr)); | |
133 | addr.sun_family = AF_UNIX; | |
134 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
135 | strlen(options.control_path) + 1; | |
136 | ||
137 | if (strlcpy(addr.sun_path, options.control_path, | |
138 | sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) | |
139 | fatal("ControlPath too long"); | |
140 | ||
141 | if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) | |
142 | fatal("%s socket(): %s", __func__, strerror(errno)); | |
143 | ||
144 | old_umask = umask(0177); | |
145 | if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) { | |
146 | muxserver_sock = -1; | |
147 | if (errno == EINVAL || errno == EADDRINUSE) { | |
148 | error("ControlSocket %s already exists, " | |
149 | "disabling multiplexing", options.control_path); | |
150 | close(muxserver_sock); | |
151 | muxserver_sock = -1; | |
152 | xfree(options.control_path); | |
153 | options.control_path = NULL; | |
154 | options.control_master = SSHCTL_MASTER_NO; | |
155 | return; | |
156 | } else | |
157 | fatal("%s bind(): %s", __func__, strerror(errno)); | |
158 | } | |
159 | umask(old_umask); | |
160 | ||
161 | if (listen(muxserver_sock, 64) == -1) | |
162 | fatal("%s listen(): %s", __func__, strerror(errno)); | |
163 | ||
164 | set_nonblock(muxserver_sock); | |
165 | } | |
166 | ||
167 | /* Callback on open confirmation in mux master for a mux client session. */ | |
168 | static void | |
169 | mux_session_confirm(int id, void *arg) | |
170 | { | |
171 | struct mux_session_confirm_ctx *cctx = arg; | |
172 | const char *display; | |
173 | Channel *c; | |
174 | int i; | |
175 | ||
176 | if (cctx == NULL) | |
177 | fatal("%s: cctx == NULL", __func__); | |
178 | if ((c = channel_lookup(id)) == NULL) | |
179 | fatal("%s: no channel for id %d", __func__, id); | |
180 | ||
181 | display = getenv("DISPLAY"); | |
182 | if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { | |
183 | char *proto, *data; | |
184 | /* Get reasonable local authentication information. */ | |
185 | client_x11_get_proto(display, options.xauth_location, | |
186 | options.forward_x11_trusted, &proto, &data); | |
187 | /* Request forwarding with authentication spoofing. */ | |
188 | debug("Requesting X11 forwarding with authentication spoofing."); | |
189 | x11_request_forwarding_with_spoofing(id, display, proto, data); | |
190 | /* XXX wait for reply */ | |
191 | } | |
192 | ||
193 | if (cctx->want_agent_fwd && options.forward_agent) { | |
194 | debug("Requesting authentication agent forwarding."); | |
195 | channel_request_start(id, "auth-agent-req@openssh.com", 0); | |
196 | packet_send(); | |
197 | } | |
198 | ||
199 | client_session2_setup(id, cctx->want_tty, cctx->want_subsys, | |
200 | cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); | |
201 | ||
202 | c->open_confirm_ctx = NULL; | |
203 | buffer_free(&cctx->cmd); | |
204 | xfree(cctx->term); | |
205 | if (cctx->env != NULL) { | |
206 | for (i = 0; cctx->env[i] != NULL; i++) | |
207 | xfree(cctx->env[i]); | |
208 | xfree(cctx->env); | |
209 | } | |
210 | xfree(cctx); | |
211 | } | |
212 | ||
213 | /* | |
214 | * Accept a connection on the mux master socket and process the | |
215 | * client's request. Returns flag indicating whether mux master should | |
216 | * begin graceful close. | |
217 | */ | |
218 | int | |
219 | muxserver_accept_control(void) | |
220 | { | |
221 | Buffer m; | |
222 | Channel *c; | |
223 | int client_fd, new_fd[3], ver, allowed, window, packetmax; | |
224 | socklen_t addrlen; | |
225 | struct sockaddr_storage addr; | |
226 | struct mux_session_confirm_ctx *cctx; | |
227 | char *cmd; | |
228 | u_int i, j, len, env_len, mux_command, flags, escape_char; | |
229 | uid_t euid; | |
230 | gid_t egid; | |
231 | int start_close = 0; | |
232 | ||
233 | /* | |
234 | * Accept connection on control socket | |
235 | */ | |
236 | memset(&addr, 0, sizeof(addr)); | |
237 | addrlen = sizeof(addr); | |
238 | if ((client_fd = accept(muxserver_sock, | |
239 | (struct sockaddr*)&addr, &addrlen)) == -1) { | |
240 | error("%s accept: %s", __func__, strerror(errno)); | |
241 | return 0; | |
242 | } | |
243 | ||
244 | if (getpeereid(client_fd, &euid, &egid) < 0) { | |
245 | error("%s getpeereid failed: %s", __func__, strerror(errno)); | |
246 | close(client_fd); | |
247 | return 0; | |
248 | } | |
249 | if ((euid != 0) && (getuid() != euid)) { | |
250 | error("control mode uid mismatch: peer euid %u != uid %u", | |
251 | (u_int) euid, (u_int) getuid()); | |
252 | close(client_fd); | |
253 | return 0; | |
254 | } | |
255 | ||
256 | /* XXX handle asynchronously */ | |
257 | unset_nonblock(client_fd); | |
258 | ||
259 | /* Read command */ | |
260 | buffer_init(&m); | |
261 | if (ssh_msg_recv(client_fd, &m) == -1) { | |
262 | error("%s: client msg_recv failed", __func__); | |
263 | close(client_fd); | |
264 | buffer_free(&m); | |
265 | return 0; | |
266 | } | |
267 | if ((ver = buffer_get_char(&m)) != SSHMUX_VER) { | |
268 | error("%s: wrong client version %d", __func__, ver); | |
269 | buffer_free(&m); | |
270 | close(client_fd); | |
271 | return 0; | |
272 | } | |
273 | ||
274 | allowed = 1; | |
275 | mux_command = buffer_get_int(&m); | |
276 | flags = buffer_get_int(&m); | |
277 | ||
278 | buffer_clear(&m); | |
279 | ||
280 | switch (mux_command) { | |
281 | case SSHMUX_COMMAND_OPEN: | |
282 | if (options.control_master == SSHCTL_MASTER_ASK || | |
283 | options.control_master == SSHCTL_MASTER_AUTO_ASK) | |
284 | allowed = ask_permission("Allow shared connection " | |
285 | "to %s? ", host); | |
286 | /* continue below */ | |
287 | break; | |
288 | case SSHMUX_COMMAND_TERMINATE: | |
289 | if (options.control_master == SSHCTL_MASTER_ASK || | |
290 | options.control_master == SSHCTL_MASTER_AUTO_ASK) | |
291 | allowed = ask_permission("Terminate shared connection " | |
292 | "to %s? ", host); | |
293 | if (allowed) | |
294 | start_close = 1; | |
295 | /* FALLTHROUGH */ | |
296 | case SSHMUX_COMMAND_ALIVE_CHECK: | |
297 | /* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */ | |
298 | buffer_clear(&m); | |
299 | buffer_put_int(&m, allowed); | |
300 | buffer_put_int(&m, getpid()); | |
301 | if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) { | |
302 | error("%s: client msg_send failed", __func__); | |
303 | close(client_fd); | |
304 | buffer_free(&m); | |
305 | return start_close; | |
306 | } | |
307 | buffer_free(&m); | |
308 | close(client_fd); | |
309 | return start_close; | |
310 | default: | |
311 | error("Unsupported command %d", mux_command); | |
312 | buffer_free(&m); | |
313 | close(client_fd); | |
314 | return 0; | |
315 | } | |
316 | ||
317 | /* Reply for SSHMUX_COMMAND_OPEN */ | |
318 | buffer_clear(&m); | |
319 | buffer_put_int(&m, allowed); | |
320 | buffer_put_int(&m, getpid()); | |
321 | if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) { | |
322 | error("%s: client msg_send failed", __func__); | |
323 | close(client_fd); | |
324 | buffer_free(&m); | |
325 | return 0; | |
326 | } | |
327 | ||
328 | if (!allowed) { | |
329 | error("Refused control connection"); | |
330 | close(client_fd); | |
331 | buffer_free(&m); | |
332 | return 0; | |
333 | } | |
334 | ||
335 | buffer_clear(&m); | |
336 | if (ssh_msg_recv(client_fd, &m) == -1) { | |
337 | error("%s: client msg_recv failed", __func__); | |
338 | close(client_fd); | |
339 | buffer_free(&m); | |
340 | return 0; | |
341 | } | |
342 | if ((ver = buffer_get_char(&m)) != SSHMUX_VER) { | |
343 | error("%s: wrong client version %d", __func__, ver); | |
344 | buffer_free(&m); | |
345 | close(client_fd); | |
346 | return 0; | |
347 | } | |
348 | ||
349 | cctx = xcalloc(1, sizeof(*cctx)); | |
350 | cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0; | |
351 | cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0; | |
352 | cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0; | |
353 | cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0; | |
354 | cctx->term = buffer_get_string(&m, &len); | |
355 | escape_char = buffer_get_int(&m); | |
356 | ||
357 | cmd = buffer_get_string(&m, &len); | |
358 | buffer_init(&cctx->cmd); | |
359 | buffer_append(&cctx->cmd, cmd, strlen(cmd)); | |
360 | ||
361 | env_len = buffer_get_int(&m); | |
362 | env_len = MIN(env_len, 4096); | |
363 | debug3("%s: receiving %d env vars", __func__, env_len); | |
364 | if (env_len != 0) { | |
365 | cctx->env = xcalloc(env_len + 1, sizeof(*cctx->env)); | |
366 | for (i = 0; i < env_len; i++) | |
367 | cctx->env[i] = buffer_get_string(&m, &len); | |
368 | cctx->env[i] = NULL; | |
369 | } | |
370 | ||
371 | debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__, | |
372 | cctx->want_tty, cctx->want_subsys, cmd); | |
373 | xfree(cmd); | |
374 | ||
375 | /* Gather fds from client */ | |
376 | for(i = 0; i < 3; i++) { | |
377 | if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) { | |
378 | error("%s: failed to receive fd %d from slave", | |
379 | __func__, i); | |
380 | for (j = 0; j < i; j++) | |
381 | close(new_fd[j]); | |
382 | for (j = 0; j < env_len; j++) | |
383 | xfree(cctx->env[j]); | |
384 | if (env_len > 0) | |
385 | xfree(cctx->env); | |
386 | xfree(cctx->term); | |
387 | buffer_free(&cctx->cmd); | |
388 | close(client_fd); | |
389 | xfree(cctx); | |
390 | return 0; | |
391 | } | |
392 | } | |
393 | ||
394 | debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__, | |
395 | new_fd[0], new_fd[1], new_fd[2]); | |
396 | ||
397 | /* Try to pick up ttymodes from client before it goes raw */ | |
398 | if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) | |
399 | error("%s: tcgetattr: %s", __func__, strerror(errno)); | |
400 | ||
401 | /* This roundtrip is just for synchronisation of ttymodes */ | |
402 | buffer_clear(&m); | |
403 | if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) { | |
404 | error("%s: client msg_send failed", __func__); | |
405 | close(client_fd); | |
406 | close(new_fd[0]); | |
407 | close(new_fd[1]); | |
408 | close(new_fd[2]); | |
409 | buffer_free(&m); | |
410 | xfree(cctx->term); | |
411 | if (env_len != 0) { | |
412 | for (i = 0; i < env_len; i++) | |
413 | xfree(cctx->env[i]); | |
414 | xfree(cctx->env); | |
415 | } | |
416 | return 0; | |
417 | } | |
418 | buffer_free(&m); | |
419 | ||
420 | /* enable nonblocking unless tty */ | |
421 | if (!isatty(new_fd[0])) | |
422 | set_nonblock(new_fd[0]); | |
423 | if (!isatty(new_fd[1])) | |
424 | set_nonblock(new_fd[1]); | |
425 | if (!isatty(new_fd[2])) | |
426 | set_nonblock(new_fd[2]); | |
427 | ||
428 | set_nonblock(client_fd); | |
429 | ||
430 | window = CHAN_SES_WINDOW_DEFAULT; | |
431 | packetmax = CHAN_SES_PACKET_DEFAULT; | |
432 | if (cctx->want_tty) { | |
433 | window >>= 1; | |
434 | packetmax >>= 1; | |
435 | } | |
436 | ||
437 | c = channel_new("session", SSH_CHANNEL_OPENING, | |
438 | new_fd[0], new_fd[1], new_fd[2], window, packetmax, | |
439 | CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); | |
440 | ||
441 | c->ctl_fd = client_fd; | |
442 | if (cctx->want_tty && escape_char != 0xffffffff) { | |
443 | channel_register_filter(c->self, | |
444 | client_simple_escape_filter, NULL, | |
445 | client_filter_cleanup, | |
446 | client_new_escape_filter_ctx((int)escape_char)); | |
447 | } | |
448 | ||
449 | debug3("%s: channel_new: %d", __func__, c->self); | |
450 | ||
451 | channel_send_open(c->self); | |
452 | channel_register_open_confirm(c->self, mux_session_confirm, cctx); | |
453 | return 0; | |
454 | } | |
455 | ||
456 | /* ** Multiplexing client support */ | |
457 | ||
458 | /* Exit signal handler */ | |
459 | static void | |
460 | control_client_sighandler(int signo) | |
461 | { | |
462 | muxclient_terminate = signo; | |
463 | } | |
464 | ||
465 | /* | |
466 | * Relay signal handler - used to pass some signals from mux client to | |
467 | * mux master. | |
468 | */ | |
469 | static void | |
470 | control_client_sigrelay(int signo) | |
471 | { | |
472 | int save_errno = errno; | |
473 | ||
474 | if (muxserver_pid > 1) | |
475 | kill(muxserver_pid, signo); | |
476 | ||
477 | errno = save_errno; | |
478 | } | |
479 | ||
480 | /* Check mux client environment variables before passing them to mux master. */ | |
481 | static int | |
482 | env_permitted(char *env) | |
483 | { | |
484 | int i, ret; | |
485 | char name[1024], *cp; | |
486 | ||
487 | if ((cp = strchr(env, '=')) == NULL || cp == env) | |
488 | return (0); | |
489 | ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); | |
490 | if (ret <= 0 || (size_t)ret >= sizeof(name)) | |
491 | fatal("env_permitted: name '%.100s...' too long", env); | |
492 | ||
493 | for (i = 0; i < options.num_send_env; i++) | |
494 | if (match_pattern(name, options.send_env[i])) | |
495 | return (1); | |
496 | ||
497 | return (0); | |
498 | } | |
499 | ||
500 | /* Multiplex client main loop. */ | |
501 | void | |
502 | muxclient(const char *path) | |
503 | { | |
504 | struct sockaddr_un addr; | |
505 | int i, r, fd, sock, exitval[2], num_env, addr_len; | |
506 | Buffer m; | |
507 | char *term; | |
508 | extern char **environ; | |
509 | u_int allowed, flags; | |
510 | ||
511 | if (muxclient_command == 0) | |
512 | muxclient_command = SSHMUX_COMMAND_OPEN; | |
513 | ||
514 | switch (options.control_master) { | |
515 | case SSHCTL_MASTER_AUTO: | |
516 | case SSHCTL_MASTER_AUTO_ASK: | |
517 | debug("auto-mux: Trying existing master"); | |
518 | /* FALLTHROUGH */ | |
519 | case SSHCTL_MASTER_NO: | |
520 | break; | |
521 | default: | |
522 | return; | |
523 | } | |
524 | ||
525 | memset(&addr, '\0', sizeof(addr)); | |
526 | addr.sun_family = AF_UNIX; | |
527 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
528 | strlen(path) + 1; | |
529 | ||
530 | if (strlcpy(addr.sun_path, path, | |
531 | sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) | |
532 | fatal("ControlPath too long"); | |
533 | ||
534 | if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) | |
535 | fatal("%s socket(): %s", __func__, strerror(errno)); | |
536 | ||
537 | if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) { | |
538 | if (muxclient_command != SSHMUX_COMMAND_OPEN) { | |
539 | fatal("Control socket connect(%.100s): %s", path, | |
540 | strerror(errno)); | |
541 | } | |
542 | if (errno == ENOENT) | |
543 | debug("Control socket \"%.100s\" does not exist", path); | |
544 | else { | |
545 | error("Control socket connect(%.100s): %s", path, | |
546 | strerror(errno)); | |
547 | } | |
548 | close(sock); | |
549 | return; | |
550 | } | |
551 | ||
552 | if (stdin_null_flag) { | |
553 | if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1) | |
554 | fatal("open(/dev/null): %s", strerror(errno)); | |
555 | if (dup2(fd, STDIN_FILENO) == -1) | |
556 | fatal("dup2: %s", strerror(errno)); | |
557 | if (fd > STDERR_FILENO) | |
558 | close(fd); | |
559 | } | |
560 | ||
561 | term = getenv("TERM"); | |
562 | ||
563 | flags = 0; | |
564 | if (tty_flag) | |
565 | flags |= SSHMUX_FLAG_TTY; | |
566 | if (subsystem_flag) | |
567 | flags |= SSHMUX_FLAG_SUBSYS; | |
568 | if (options.forward_x11) | |
569 | flags |= SSHMUX_FLAG_X11_FWD; | |
570 | if (options.forward_agent) | |
571 | flags |= SSHMUX_FLAG_AGENT_FWD; | |
572 | ||
573 | signal(SIGPIPE, SIG_IGN); | |
574 | ||
575 | buffer_init(&m); | |
576 | ||
577 | /* Send our command to server */ | |
578 | buffer_put_int(&m, muxclient_command); | |
579 | buffer_put_int(&m, flags); | |
580 | if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) { | |
581 | error("%s: msg_send", __func__); | |
582 | muxerr: | |
583 | close(sock); | |
584 | buffer_free(&m); | |
585 | if (muxclient_command != SSHMUX_COMMAND_OPEN) | |
586 | cleanup_exit(255); | |
587 | logit("Falling back to non-multiplexed connection"); | |
588 | xfree(options.control_path); | |
589 | options.control_path = NULL; | |
590 | options.control_master = SSHCTL_MASTER_NO; | |
591 | return; | |
592 | } | |
593 | buffer_clear(&m); | |
594 | ||
595 | /* Get authorisation status and PID of controlee */ | |
596 | if (ssh_msg_recv(sock, &m) == -1) { | |
597 | error("%s: Did not receive reply from master", __func__); | |
598 | goto muxerr; | |
599 | } | |
600 | if (buffer_get_char(&m) != SSHMUX_VER) { | |
601 | error("%s: Master replied with wrong version", __func__); | |
602 | goto muxerr; | |
603 | } | |
604 | if (buffer_get_int_ret(&allowed, &m) != 0) { | |
605 | error("%s: bad server reply", __func__); | |
606 | goto muxerr; | |
607 | } | |
608 | if (allowed != 1) { | |
609 | error("Connection to master denied"); | |
610 | goto muxerr; | |
611 | } | |
612 | muxserver_pid = buffer_get_int(&m); | |
613 | ||
614 | buffer_clear(&m); | |
615 | ||
616 | switch (muxclient_command) { | |
617 | case SSHMUX_COMMAND_ALIVE_CHECK: | |
618 | fprintf(stderr, "Master running (pid=%d)\r\n", | |
619 | muxserver_pid); | |
620 | exit(0); | |
621 | case SSHMUX_COMMAND_TERMINATE: | |
622 | fprintf(stderr, "Exit request sent.\r\n"); | |
623 | exit(0); | |
624 | case SSHMUX_COMMAND_OPEN: | |
625 | buffer_put_cstring(&m, term ? term : ""); | |
626 | if (options.escape_char == SSH_ESCAPECHAR_NONE) | |
627 | buffer_put_int(&m, 0xffffffff); | |
628 | else | |
629 | buffer_put_int(&m, options.escape_char); | |
630 | buffer_append(&command, "\0", 1); | |
631 | buffer_put_cstring(&m, buffer_ptr(&command)); | |
632 | ||
633 | if (options.num_send_env == 0 || environ == NULL) { | |
634 | buffer_put_int(&m, 0); | |
635 | } else { | |
636 | /* Pass environment */ | |
637 | num_env = 0; | |
638 | for (i = 0; environ[i] != NULL; i++) { | |
639 | if (env_permitted(environ[i])) | |
640 | num_env++; /* Count */ | |
641 | } | |
642 | buffer_put_int(&m, num_env); | |
643 | for (i = 0; environ[i] != NULL && num_env >= 0; i++) { | |
644 | if (env_permitted(environ[i])) { | |
645 | num_env--; | |
646 | buffer_put_cstring(&m, environ[i]); | |
647 | } | |
648 | } | |
649 | } | |
650 | break; | |
651 | default: | |
652 | fatal("unrecognised muxclient_command %d", muxclient_command); | |
653 | } | |
654 | ||
655 | if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) { | |
656 | error("%s: msg_send", __func__); | |
657 | goto muxerr; | |
658 | } | |
659 | ||
660 | if (mm_send_fd(sock, STDIN_FILENO) == -1 || | |
661 | mm_send_fd(sock, STDOUT_FILENO) == -1 || | |
662 | mm_send_fd(sock, STDERR_FILENO) == -1) { | |
663 | error("%s: send fds failed", __func__); | |
664 | goto muxerr; | |
665 | } | |
666 | ||
667 | /* | |
668 | * Mux errors are non-recoverable from this point as the master | |
669 | * has ownership of the session now. | |
670 | */ | |
671 | ||
672 | /* Wait for reply, so master has a chance to gather ttymodes */ | |
673 | buffer_clear(&m); | |
674 | if (ssh_msg_recv(sock, &m) == -1) | |
675 | fatal("%s: msg_recv", __func__); | |
676 | if (buffer_get_char(&m) != SSHMUX_VER) | |
677 | fatal("%s: wrong version", __func__); | |
678 | buffer_free(&m); | |
679 | ||
680 | signal(SIGHUP, control_client_sighandler); | |
681 | signal(SIGINT, control_client_sighandler); | |
682 | signal(SIGTERM, control_client_sighandler); | |
683 | signal(SIGWINCH, control_client_sigrelay); | |
684 | ||
685 | if (tty_flag) | |
686 | enter_raw_mode(); | |
687 | ||
688 | /* | |
689 | * Stick around until the controlee closes the client_fd. | |
690 | * Before it does, it is expected to write this process' exit | |
691 | * value (one int). This process must read the value and wait for | |
692 | * the closure of the client_fd; if this one closes early, the | |
693 | * multiplex master will terminate early too (possibly losing data). | |
694 | */ | |
695 | exitval[0] = 0; | |
696 | for (i = 0; !muxclient_terminate && i < (int)sizeof(exitval);) { | |
697 | r = read(sock, (char *)exitval + i, sizeof(exitval) - i); | |
698 | if (r == 0) { | |
699 | debug2("Received EOF from master"); | |
700 | break; | |
701 | } | |
702 | if (r == -1) { | |
703 | if (errno == EINTR) | |
704 | continue; | |
705 | fatal("%s: read %s", __func__, strerror(errno)); | |
706 | } | |
707 | i += r; | |
708 | } | |
709 | ||
710 | close(sock); | |
711 | leave_raw_mode(); | |
712 | if (i > (int)sizeof(int)) | |
713 | fatal("%s: master returned too much data (%d > %lu)", | |
714 | __func__, i, (u_long)sizeof(int)); | |
715 | if (muxclient_terminate) { | |
716 | debug2("Exiting on signal %d", muxclient_terminate); | |
717 | exitval[0] = 255; | |
718 | } else if (i < (int)sizeof(int)) { | |
719 | debug2("Control master terminated unexpectedly"); | |
720 | exitval[0] = 255; | |
721 | } else | |
722 | debug2("Received exit status from master %d", exitval[0]); | |
723 | ||
724 | if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) | |
725 | fprintf(stderr, "Shared connection to %s closed.\r\n", host); | |
726 | ||
727 | exit(exitval[0]); | |
728 | } |