1 /* $OpenBSD: mux.c,v 1.29 2011/06/22 22:08:42 djm Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 /* 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 35 #include <sys/types.h> 36 #include <sys/param.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 #ifdef HAVE_LIBUTIL_H 67 # include <libutil.h> 68 #endif 69 70 #include "openbsd-compat/sys-queue.h" 71 #include "xmalloc.h" 72 #include "log.h" 73 #include "ssh.h" 74 #include "ssh2.h" 75 #include "pathnames.h" 76 #include "misc.h" 77 #include "match.h" 78 #include "buffer.h" 79 #include "channels.h" 80 #include "msg.h" 81 #include "packet.h" 82 #include "monitor_fdpass.h" 83 #include "sshpty.h" 84 #include "key.h" 85 #include "readconf.h" 86 #include "clientloop.h" 87 88 /* from ssh.c */ 89 extern int tty_flag; 90 extern Options options; 91 extern int stdin_null_flag; 92 extern char *host; 93 extern int subsystem_flag; 94 extern Buffer command; 95 extern volatile sig_atomic_t quit_pending; 96 extern char *stdio_forward_host; 97 extern int stdio_forward_port; 98 99 /* Context for session open confirmation callback */ 100 struct mux_session_confirm_ctx { 101 u_int want_tty; 102 u_int want_subsys; 103 u_int want_x_fwd; 104 u_int want_agent_fwd; 105 Buffer cmd; 106 char *term; 107 struct termios tio; 108 char **env; 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_S_OK 0x80000001 150 #define MUX_S_PERMISSION_DENIED 0x80000002 151 #define MUX_S_FAILURE 0x80000003 152 #define MUX_S_EXIT_MESSAGE 0x80000004 153 #define MUX_S_ALIVE 0x80000005 154 #define MUX_S_SESSION_OPENED 0x80000006 155 #define MUX_S_REMOTE_PORT 0x80000007 156 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 157 158 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 159 #define MUX_FWD_LOCAL 1 160 #define MUX_FWD_REMOTE 2 161 #define MUX_FWD_DYNAMIC 3 162 163 static void mux_session_confirm(int, int, void *); 164 165 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 166 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 167 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 168 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 169 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 170 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 171 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 172 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 173 174 static const struct { 175 u_int type; 176 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 177 } mux_master_handlers[] = { 178 { MUX_MSG_HELLO, process_mux_master_hello }, 179 { MUX_C_NEW_SESSION, process_mux_new_session }, 180 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 181 { MUX_C_TERMINATE, process_mux_terminate }, 182 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 183 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 184 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 185 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 186 { 0, NULL } 187 }; 188 189 /* Cleanup callback fired on closure of mux slave _session_ channel */ 190 /* ARGSUSED */ 191 static void 192 mux_master_session_cleanup_cb(int cid, void *unused) 193 { 194 Channel *cc, *c = channel_by_id(cid); 195 196 debug3("%s: entering for channel %d", __func__, cid); 197 if (c == NULL) 198 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 199 if (c->ctl_chan != -1) { 200 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 201 fatal("%s: channel %d missing control channel %d", 202 __func__, c->self, c->ctl_chan); 203 c->ctl_chan = -1; 204 cc->remote_id = -1; 205 chan_rcvd_oclose(cc); 206 } 207 channel_cancel_cleanup(c->self); 208 } 209 210 /* Cleanup callback fired on closure of mux slave _control_ channel */ 211 /* ARGSUSED */ 212 static void 213 mux_master_control_cleanup_cb(int cid, void *unused) 214 { 215 Channel *sc, *c = channel_by_id(cid); 216 217 debug3("%s: entering for channel %d", __func__, cid); 218 if (c == NULL) 219 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 220 if (c->remote_id != -1) { 221 if ((sc = channel_by_id(c->remote_id)) == NULL) 222 fatal("%s: channel %d missing session channel %d", 223 __func__, c->self, c->remote_id); 224 c->remote_id = -1; 225 sc->ctl_chan = -1; 226 if (sc->type != SSH_CHANNEL_OPEN) { 227 debug2("%s: channel %d: not open", __func__, sc->self); 228 chan_mark_dead(sc); 229 } else { 230 if (sc->istate == CHAN_INPUT_OPEN) 231 chan_read_failed(sc); 232 if (sc->ostate == CHAN_OUTPUT_OPEN) 233 chan_write_failed(sc); 234 } 235 } 236 channel_cancel_cleanup(c->self); 237 } 238 239 /* Check mux client environment variables before passing them to mux master. */ 240 static int 241 env_permitted(char *env) 242 { 243 int i, ret; 244 char name[1024], *cp; 245 246 if ((cp = strchr(env, '=')) == NULL || cp == env) 247 return 0; 248 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 249 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 250 error("env_permitted: name '%.100s...' too long", env); 251 return 0; 252 } 253 254 for (i = 0; i < options.num_send_env; i++) 255 if (match_pattern(name, options.send_env[i])) 256 return 1; 257 258 return 0; 259 } 260 261 /* Mux master protocol message handlers */ 262 263 static int 264 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 265 { 266 u_int ver; 267 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 268 269 if (state == NULL) 270 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 271 if (state->hello_rcvd) { 272 error("%s: HELLO received twice", __func__); 273 return -1; 274 } 275 if (buffer_get_int_ret(&ver, m) != 0) { 276 malf: 277 error("%s: malformed message", __func__); 278 return -1; 279 } 280 if (ver != SSHMUX_VER) { 281 error("Unsupported multiplexing protocol version %d " 282 "(expected %d)", ver, SSHMUX_VER); 283 return -1; 284 } 285 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 286 287 /* No extensions are presently defined */ 288 while (buffer_len(m) > 0) { 289 char *name = buffer_get_string_ret(m, NULL); 290 char *value = buffer_get_string_ret(m, NULL); 291 292 if (name == NULL || value == NULL) { 293 if (name != NULL) 294 xfree(name); 295 goto malf; 296 } 297 debug2("Unrecognised slave extension \"%s\"", name); 298 xfree(name); 299 xfree(value); 300 } 301 state->hello_rcvd = 1; 302 return 0; 303 } 304 305 static int 306 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 307 { 308 Channel *nc; 309 struct mux_session_confirm_ctx *cctx; 310 char *reserved, *cmd, *cp; 311 u_int i, j, len, env_len, escape_char, window, packetmax; 312 int new_fd[3]; 313 314 /* Reply for SSHMUX_COMMAND_OPEN */ 315 cctx = xcalloc(1, sizeof(*cctx)); 316 cctx->term = NULL; 317 cctx->rid = rid; 318 cmd = reserved = NULL; 319 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 320 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 321 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 322 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 323 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 324 buffer_get_int_ret(&escape_char, m) != 0 || 325 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 326 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 327 malf: 328 if (cmd != NULL) 329 xfree(cmd); 330 if (reserved != NULL) 331 xfree(reserved); 332 if (cctx->term != NULL) 333 xfree(cctx->term); 334 error("%s: malformed message", __func__); 335 return -1; 336 } 337 xfree(reserved); 338 reserved = NULL; 339 340 cctx->env = NULL; 341 env_len = 0; 342 while (buffer_len(m) > 0) { 343 #define MUX_MAX_ENV_VARS 4096 344 if ((cp = buffer_get_string_ret(m, &len)) == NULL) { 345 xfree(cmd); 346 goto malf; 347 } 348 if (!env_permitted(cp)) { 349 xfree(cp); 350 continue; 351 } 352 cctx->env = xrealloc(cctx->env, env_len + 2, 353 sizeof(*cctx->env)); 354 cctx->env[env_len++] = cp; 355 cctx->env[env_len] = NULL; 356 if (env_len > MUX_MAX_ENV_VARS) { 357 error(">%d environment variables received, ignoring " 358 "additional", MUX_MAX_ENV_VARS); 359 break; 360 } 361 } 362 363 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 364 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 365 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 366 cctx->want_subsys, cctx->term, cmd, env_len); 367 368 buffer_init(&cctx->cmd); 369 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 370 xfree(cmd); 371 cmd = NULL; 372 373 /* Gather fds from client */ 374 for(i = 0; i < 3; i++) { 375 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 376 error("%s: failed to receive fd %d from slave", 377 __func__, i); 378 for (j = 0; j < i; j++) 379 close(new_fd[j]); 380 for (j = 0; j < env_len; j++) 381 xfree(cctx->env[j]); 382 if (env_len > 0) 383 xfree(cctx->env); 384 xfree(cctx->term); 385 buffer_free(&cctx->cmd); 386 xfree(cctx); 387 388 /* prepare reply */ 389 buffer_put_int(r, MUX_S_FAILURE); 390 buffer_put_int(r, rid); 391 buffer_put_cstring(r, 392 "did not receive file descriptors"); 393 return -1; 394 } 395 } 396 397 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 398 new_fd[0], new_fd[1], new_fd[2]); 399 400 /* XXX support multiple child sessions in future */ 401 if (c->remote_id != -1) { 402 debug2("%s: session already open", __func__); 403 /* prepare reply */ 404 buffer_put_int(r, MUX_S_FAILURE); 405 buffer_put_int(r, rid); 406 buffer_put_cstring(r, "Multiple sessions not supported"); 407 cleanup: 408 close(new_fd[0]); 409 close(new_fd[1]); 410 close(new_fd[2]); 411 xfree(cctx->term); 412 if (env_len != 0) { 413 for (i = 0; i < env_len; i++) 414 xfree(cctx->env[i]); 415 xfree(cctx->env); 416 } 417 buffer_free(&cctx->cmd); 418 return 0; 419 } 420 421 if (options.control_master == SSHCTL_MASTER_ASK || 422 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 423 if (!ask_permission("Allow shared connection to %s? ", host)) { 424 debug2("%s: session refused by user", __func__); 425 /* prepare reply */ 426 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 427 buffer_put_int(r, rid); 428 buffer_put_cstring(r, "Permission denied"); 429 goto cleanup; 430 } 431 } 432 433 /* Try to pick up ttymodes from client before it goes raw */ 434 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 435 error("%s: tcgetattr: %s", __func__, strerror(errno)); 436 437 /* enable nonblocking unless tty */ 438 if (!isatty(new_fd[0])) 439 set_nonblock(new_fd[0]); 440 if (!isatty(new_fd[1])) 441 set_nonblock(new_fd[1]); 442 if (!isatty(new_fd[2])) 443 set_nonblock(new_fd[2]); 444 445 window = CHAN_SES_WINDOW_DEFAULT; 446 packetmax = CHAN_SES_PACKET_DEFAULT; 447 if (cctx->want_tty) { 448 window >>= 1; 449 packetmax >>= 1; 450 } 451 452 nc = channel_new("session", SSH_CHANNEL_OPENING, 453 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 454 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 455 456 nc->ctl_chan = c->self; /* link session -> control channel */ 457 c->remote_id = nc->self; /* link control -> session channel */ 458 459 if (cctx->want_tty && escape_char != 0xffffffff) { 460 channel_register_filter(nc->self, 461 client_simple_escape_filter, NULL, 462 client_filter_cleanup, 463 client_new_escape_filter_ctx((int)escape_char)); 464 } 465 466 debug2("%s: channel_new: %d linked to control channel %d", 467 __func__, nc->self, nc->ctl_chan); 468 469 channel_send_open(nc->self); 470 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 471 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 472 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 473 474 /* reply is deferred, sent by mux_session_confirm */ 475 return 0; 476 } 477 478 static int 479 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 480 { 481 debug2("%s: channel %d: alive check", __func__, c->self); 482 483 /* prepare reply */ 484 buffer_put_int(r, MUX_S_ALIVE); 485 buffer_put_int(r, rid); 486 buffer_put_int(r, (u_int)getpid()); 487 488 return 0; 489 } 490 491 static int 492 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 493 { 494 debug2("%s: channel %d: terminate request", __func__, c->self); 495 496 if (options.control_master == SSHCTL_MASTER_ASK || 497 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 498 if (!ask_permission("Terminate shared connection to %s? ", 499 host)) { 500 debug2("%s: termination refused by user", __func__); 501 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 502 buffer_put_int(r, rid); 503 buffer_put_cstring(r, "Permission denied"); 504 return 0; 505 } 506 } 507 508 quit_pending = 1; 509 buffer_put_int(r, MUX_S_OK); 510 buffer_put_int(r, rid); 511 /* XXX exit happens too soon - message never makes it to client */ 512 return 0; 513 } 514 515 static char * 516 format_forward(u_int ftype, Forward *fwd) 517 { 518 char *ret; 519 520 switch (ftype) { 521 case MUX_FWD_LOCAL: 522 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 523 (fwd->listen_host == NULL) ? 524 (options.gateway_ports ? "*" : "LOCALHOST") : 525 fwd->listen_host, fwd->listen_port, 526 fwd->connect_host, fwd->connect_port); 527 break; 528 case MUX_FWD_DYNAMIC: 529 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 530 (fwd->listen_host == NULL) ? 531 (options.gateway_ports ? "*" : "LOCALHOST") : 532 fwd->listen_host, fwd->listen_port); 533 break; 534 case MUX_FWD_REMOTE: 535 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 536 (fwd->listen_host == NULL) ? 537 "LOCALHOST" : fwd->listen_host, 538 fwd->listen_port, 539 fwd->connect_host, fwd->connect_port); 540 break; 541 default: 542 fatal("%s: unknown forward type %u", __func__, ftype); 543 } 544 return ret; 545 } 546 547 static int 548 compare_host(const char *a, const char *b) 549 { 550 if (a == NULL && b == NULL) 551 return 1; 552 if (a == NULL || b == NULL) 553 return 0; 554 return strcmp(a, b) == 0; 555 } 556 557 static int 558 compare_forward(Forward *a, Forward *b) 559 { 560 if (!compare_host(a->listen_host, b->listen_host)) 561 return 0; 562 if (a->listen_port != b->listen_port) 563 return 0; 564 if (!compare_host(a->connect_host, b->connect_host)) 565 return 0; 566 if (a->connect_port != b->connect_port) 567 return 0; 568 569 return 1; 570 } 571 572 static void 573 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 574 { 575 struct mux_channel_confirm_ctx *fctx = ctxt; 576 char *failmsg = NULL; 577 Forward *rfwd; 578 Channel *c; 579 Buffer out; 580 581 if ((c = channel_by_id(fctx->cid)) == NULL) { 582 /* no channel for reply */ 583 error("%s: unknown channel", __func__); 584 return; 585 } 586 buffer_init(&out); 587 if (fctx->fid >= options.num_remote_forwards) { 588 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 589 goto fail; 590 } 591 rfwd = &options.remote_forwards[fctx->fid]; 592 debug("%s: %s for: listen %d, connect %s:%d", __func__, 593 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 594 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); 595 if (type == SSH2_MSG_REQUEST_SUCCESS) { 596 if (rfwd->listen_port == 0) { 597 rfwd->allocated_port = packet_get_int(); 598 logit("Allocated port %u for mux remote forward" 599 " to %s:%d", rfwd->allocated_port, 600 rfwd->connect_host, rfwd->connect_port); 601 buffer_put_int(&out, MUX_S_REMOTE_PORT); 602 buffer_put_int(&out, fctx->rid); 603 buffer_put_int(&out, rfwd->allocated_port); 604 } else { 605 buffer_put_int(&out, MUX_S_OK); 606 buffer_put_int(&out, fctx->rid); 607 } 608 goto out; 609 } else { 610 xasprintf(&failmsg, "remote port forwarding failed for " 611 "listen port %d", rfwd->listen_port); 612 } 613 fail: 614 error("%s: %s", __func__, failmsg); 615 buffer_put_int(&out, MUX_S_FAILURE); 616 buffer_put_int(&out, fctx->rid); 617 buffer_put_cstring(&out, failmsg); 618 xfree(failmsg); 619 out: 620 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 621 buffer_free(&out); 622 if (c->mux_pause <= 0) 623 fatal("%s: mux_pause %d", __func__, c->mux_pause); 624 c->mux_pause = 0; /* start processing messages again */ 625 } 626 627 static int 628 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 629 { 630 Forward fwd; 631 char *fwd_desc = NULL; 632 u_int ftype; 633 int i, ret = 0, freefwd = 1; 634 635 fwd.listen_host = fwd.connect_host = NULL; 636 if (buffer_get_int_ret(&ftype, m) != 0 || 637 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 638 buffer_get_int_ret(&fwd.listen_port, m) != 0 || 639 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 640 buffer_get_int_ret(&fwd.connect_port, m) != 0) { 641 error("%s: malformed message", __func__); 642 ret = -1; 643 goto out; 644 } 645 646 if (*fwd.listen_host == '\0') { 647 xfree(fwd.listen_host); 648 fwd.listen_host = NULL; 649 } 650 if (*fwd.connect_host == '\0') { 651 xfree(fwd.connect_host); 652 fwd.connect_host = NULL; 653 } 654 655 debug2("%s: channel %d: request %s", __func__, c->self, 656 (fwd_desc = format_forward(ftype, &fwd))); 657 658 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 659 ftype != MUX_FWD_DYNAMIC) { 660 logit("%s: invalid forwarding type %u", __func__, ftype); 661 invalid: 662 if (fwd.listen_host) 663 xfree(fwd.listen_host); 664 if (fwd.connect_host) 665 xfree(fwd.connect_host); 666 buffer_put_int(r, MUX_S_FAILURE); 667 buffer_put_int(r, rid); 668 buffer_put_cstring(r, "Invalid forwarding request"); 669 return 0; 670 } 671 if (fwd.listen_port >= 65536) { 672 logit("%s: invalid listen port %u", __func__, 673 fwd.listen_port); 674 goto invalid; 675 } 676 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC && 677 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 678 logit("%s: invalid connect port %u", __func__, 679 fwd.connect_port); 680 goto invalid; 681 } 682 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) { 683 logit("%s: missing connect host", __func__); 684 goto invalid; 685 } 686 687 /* Skip forwards that have already been requested */ 688 switch (ftype) { 689 case MUX_FWD_LOCAL: 690 case MUX_FWD_DYNAMIC: 691 for (i = 0; i < options.num_local_forwards; i++) { 692 if (compare_forward(&fwd, 693 options.local_forwards + i)) { 694 exists: 695 debug2("%s: found existing forwarding", 696 __func__); 697 buffer_put_int(r, MUX_S_OK); 698 buffer_put_int(r, rid); 699 goto out; 700 } 701 } 702 break; 703 case MUX_FWD_REMOTE: 704 for (i = 0; i < options.num_remote_forwards; i++) { 705 if (compare_forward(&fwd, 706 options.remote_forwards + i)) { 707 if (fwd.listen_port != 0) 708 goto exists; 709 debug2("%s: found allocated port", 710 __func__); 711 buffer_put_int(r, MUX_S_REMOTE_PORT); 712 buffer_put_int(r, rid); 713 buffer_put_int(r, 714 options.remote_forwards[i].allocated_port); 715 goto out; 716 } 717 } 718 break; 719 } 720 721 if (options.control_master == SSHCTL_MASTER_ASK || 722 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 723 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 724 debug2("%s: forwarding refused by user", __func__); 725 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 726 buffer_put_int(r, rid); 727 buffer_put_cstring(r, "Permission denied"); 728 goto out; 729 } 730 } 731 732 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 733 if (channel_setup_local_fwd_listener(fwd.listen_host, 734 fwd.listen_port, fwd.connect_host, fwd.connect_port, 735 options.gateway_ports) < 0) { 736 fail: 737 logit("slave-requested %s failed", fwd_desc); 738 buffer_put_int(r, MUX_S_FAILURE); 739 buffer_put_int(r, rid); 740 buffer_put_cstring(r, "Port forwarding failed"); 741 goto out; 742 } 743 add_local_forward(&options, &fwd); 744 freefwd = 0; 745 } else { 746 struct mux_channel_confirm_ctx *fctx; 747 748 if (channel_request_remote_forwarding(fwd.listen_host, 749 fwd.listen_port, fwd.connect_host, fwd.connect_port) < 0) 750 goto fail; 751 add_remote_forward(&options, &fwd); 752 fctx = xcalloc(1, sizeof(*fctx)); 753 fctx->cid = c->self; 754 fctx->rid = rid; 755 fctx->fid = options.num_remote_forwards - 1; 756 client_register_global_confirm(mux_confirm_remote_forward, 757 fctx); 758 freefwd = 0; 759 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 760 /* delayed reply in mux_confirm_remote_forward */ 761 goto out; 762 } 763 buffer_put_int(r, MUX_S_OK); 764 buffer_put_int(r, rid); 765 out: 766 if (fwd_desc != NULL) 767 xfree(fwd_desc); 768 if (freefwd) { 769 if (fwd.listen_host != NULL) 770 xfree(fwd.listen_host); 771 if (fwd.connect_host != NULL) 772 xfree(fwd.connect_host); 773 } 774 return ret; 775 } 776 777 static int 778 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 779 { 780 Forward fwd; 781 char *fwd_desc = NULL; 782 u_int ftype; 783 int ret = 0; 784 785 fwd.listen_host = fwd.connect_host = NULL; 786 if (buffer_get_int_ret(&ftype, m) != 0 || 787 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 788 buffer_get_int_ret(&fwd.listen_port, m) != 0 || 789 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 790 buffer_get_int_ret(&fwd.connect_port, m) != 0) { 791 error("%s: malformed message", __func__); 792 ret = -1; 793 goto out; 794 } 795 796 if (*fwd.listen_host == '\0') { 797 xfree(fwd.listen_host); 798 fwd.listen_host = NULL; 799 } 800 if (*fwd.connect_host == '\0') { 801 xfree(fwd.connect_host); 802 fwd.connect_host = NULL; 803 } 804 805 debug2("%s: channel %d: request %s", __func__, c->self, 806 (fwd_desc = format_forward(ftype, &fwd))); 807 808 /* XXX implement this */ 809 buffer_put_int(r, MUX_S_FAILURE); 810 buffer_put_int(r, rid); 811 buffer_put_cstring(r, "unimplemented"); 812 813 out: 814 if (fwd_desc != NULL) 815 xfree(fwd_desc); 816 if (fwd.listen_host != NULL) 817 xfree(fwd.listen_host); 818 if (fwd.connect_host != NULL) 819 xfree(fwd.connect_host); 820 821 return ret; 822 } 823 824 static int 825 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 826 { 827 Channel *nc; 828 char *reserved, *chost; 829 u_int cport, i, j; 830 int new_fd[2]; 831 832 chost = reserved = NULL; 833 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 834 (chost = buffer_get_string_ret(m, NULL)) == NULL || 835 buffer_get_int_ret(&cport, m) != 0) { 836 if (reserved != NULL) 837 xfree(reserved); 838 if (chost != NULL) 839 xfree(chost); 840 error("%s: malformed message", __func__); 841 return -1; 842 } 843 xfree(reserved); 844 845 debug2("%s: channel %d: request stdio fwd to %s:%u", 846 __func__, c->self, chost, cport); 847 848 /* Gather fds from client */ 849 for(i = 0; i < 2; i++) { 850 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 851 error("%s: failed to receive fd %d from slave", 852 __func__, i); 853 for (j = 0; j < i; j++) 854 close(new_fd[j]); 855 xfree(chost); 856 857 /* prepare reply */ 858 buffer_put_int(r, MUX_S_FAILURE); 859 buffer_put_int(r, rid); 860 buffer_put_cstring(r, 861 "did not receive file descriptors"); 862 return -1; 863 } 864 } 865 866 debug3("%s: got fds stdin %d, stdout %d", __func__, 867 new_fd[0], new_fd[1]); 868 869 /* XXX support multiple child sessions in future */ 870 if (c->remote_id != -1) { 871 debug2("%s: session already open", __func__); 872 /* prepare reply */ 873 buffer_put_int(r, MUX_S_FAILURE); 874 buffer_put_int(r, rid); 875 buffer_put_cstring(r, "Multiple sessions not supported"); 876 cleanup: 877 close(new_fd[0]); 878 close(new_fd[1]); 879 xfree(chost); 880 return 0; 881 } 882 883 if (options.control_master == SSHCTL_MASTER_ASK || 884 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 885 if (!ask_permission("Allow forward to %s:%u? ", 886 chost, cport)) { 887 debug2("%s: stdio fwd refused by user", __func__); 888 /* prepare reply */ 889 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 890 buffer_put_int(r, rid); 891 buffer_put_cstring(r, "Permission denied"); 892 goto cleanup; 893 } 894 } 895 896 /* enable nonblocking unless tty */ 897 if (!isatty(new_fd[0])) 898 set_nonblock(new_fd[0]); 899 if (!isatty(new_fd[1])) 900 set_nonblock(new_fd[1]); 901 902 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 903 904 nc->ctl_chan = c->self; /* link session -> control channel */ 905 c->remote_id = nc->self; /* link control -> session channel */ 906 907 debug2("%s: channel_new: %d linked to control channel %d", 908 __func__, nc->self, nc->ctl_chan); 909 910 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 911 912 /* prepare reply */ 913 /* XXX defer until channel confirmed */ 914 buffer_put_int(r, MUX_S_SESSION_OPENED); 915 buffer_put_int(r, rid); 916 buffer_put_int(r, nc->self); 917 918 return 0; 919 } 920 921 static int 922 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 923 { 924 debug("%s: channel %d: stop listening", __func__, c->self); 925 926 if (options.control_master == SSHCTL_MASTER_ASK || 927 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 928 if (!ask_permission("Disable further multiplexing on shared " 929 "connection to %s? ", host)) { 930 debug2("%s: stop listen refused by user", __func__); 931 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 932 buffer_put_int(r, rid); 933 buffer_put_cstring(r, "Permission denied"); 934 return 0; 935 } 936 } 937 938 if (mux_listener_channel != NULL) { 939 channel_free(mux_listener_channel); 940 client_stop_mux(); 941 xfree(options.control_path); 942 options.control_path = NULL; 943 mux_listener_channel = NULL; 944 muxserver_sock = -1; 945 } 946 947 /* prepare reply */ 948 buffer_put_int(r, MUX_S_OK); 949 buffer_put_int(r, rid); 950 951 return 0; 952 } 953 954 /* Channel callbacks fired on read/write from mux slave fd */ 955 static int 956 mux_master_read_cb(Channel *c) 957 { 958 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 959 Buffer in, out; 960 void *ptr; 961 u_int type, rid, have, i; 962 int ret = -1; 963 964 /* Setup ctx and */ 965 if (c->mux_ctx == NULL) { 966 state = xcalloc(1, sizeof(*state)); 967 c->mux_ctx = state; 968 channel_register_cleanup(c->self, 969 mux_master_control_cleanup_cb, 0); 970 971 /* Send hello */ 972 buffer_init(&out); 973 buffer_put_int(&out, MUX_MSG_HELLO); 974 buffer_put_int(&out, SSHMUX_VER); 975 /* no extensions */ 976 buffer_put_string(&c->output, buffer_ptr(&out), 977 buffer_len(&out)); 978 buffer_free(&out); 979 debug3("%s: channel %d: hello sent", __func__, c->self); 980 return 0; 981 } 982 983 buffer_init(&in); 984 buffer_init(&out); 985 986 /* Channel code ensures that we receive whole packets */ 987 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 988 malf: 989 error("%s: malformed message", __func__); 990 goto out; 991 } 992 buffer_append(&in, ptr, have); 993 994 if (buffer_get_int_ret(&type, &in) != 0) 995 goto malf; 996 debug3("%s: channel %d packet type 0x%08x len %u", 997 __func__, c->self, type, buffer_len(&in)); 998 999 if (type == MUX_MSG_HELLO) 1000 rid = 0; 1001 else { 1002 if (!state->hello_rcvd) { 1003 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1004 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1005 goto out; 1006 } 1007 if (buffer_get_int_ret(&rid, &in) != 0) 1008 goto malf; 1009 } 1010 1011 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1012 if (type == mux_master_handlers[i].type) { 1013 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1014 break; 1015 } 1016 } 1017 if (mux_master_handlers[i].handler == NULL) { 1018 error("%s: unsupported mux message 0x%08x", __func__, type); 1019 buffer_put_int(&out, MUX_S_FAILURE); 1020 buffer_put_int(&out, rid); 1021 buffer_put_cstring(&out, "unsupported request"); 1022 ret = 0; 1023 } 1024 /* Enqueue reply packet */ 1025 if (buffer_len(&out) != 0) { 1026 buffer_put_string(&c->output, buffer_ptr(&out), 1027 buffer_len(&out)); 1028 } 1029 out: 1030 buffer_free(&in); 1031 buffer_free(&out); 1032 return ret; 1033 } 1034 1035 void 1036 mux_exit_message(Channel *c, int exitval) 1037 { 1038 Buffer m; 1039 Channel *mux_chan; 1040 1041 debug3("%s: channel %d: exit message, evitval %d", __func__, c->self, 1042 exitval); 1043 1044 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1045 fatal("%s: channel %d missing mux channel %d", 1046 __func__, c->self, c->ctl_chan); 1047 1048 /* Append exit message packet to control socket output queue */ 1049 buffer_init(&m); 1050 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1051 buffer_put_int(&m, c->self); 1052 buffer_put_int(&m, exitval); 1053 1054 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1055 buffer_free(&m); 1056 } 1057 1058 void 1059 mux_tty_alloc_failed(Channel *c) 1060 { 1061 Buffer m; 1062 Channel *mux_chan; 1063 1064 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1065 1066 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1067 fatal("%s: channel %d missing mux channel %d", 1068 __func__, c->self, c->ctl_chan); 1069 1070 /* Append exit message packet to control socket output queue */ 1071 buffer_init(&m); 1072 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1073 buffer_put_int(&m, c->self); 1074 1075 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1076 buffer_free(&m); 1077 } 1078 1079 /* Prepare a mux master to listen on a Unix domain socket. */ 1080 void 1081 muxserver_listen(void) 1082 { 1083 struct sockaddr_un addr; 1084 socklen_t sun_len; 1085 mode_t old_umask; 1086 char *orig_control_path = options.control_path; 1087 char rbuf[16+1]; 1088 u_int i, r; 1089 1090 if (options.control_path == NULL || 1091 options.control_master == SSHCTL_MASTER_NO) 1092 return; 1093 1094 debug("setting up multiplex master socket"); 1095 1096 /* 1097 * Use a temporary path before listen so we can pseudo-atomically 1098 * establish the listening socket in its final location to avoid 1099 * other processes racing in between bind() and listen() and hitting 1100 * an unready socket. 1101 */ 1102 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1103 r = arc4random_uniform(26+26+10); 1104 rbuf[i] = (r < 26) ? 'a' + r : 1105 (r < 26*2) ? 'A' + r - 26 : 1106 '0' + r - 26 - 26; 1107 } 1108 rbuf[sizeof(rbuf) - 1] = '\0'; 1109 options.control_path = NULL; 1110 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1111 debug3("%s: temporary control path %s", __func__, options.control_path); 1112 1113 memset(&addr, '\0', sizeof(addr)); 1114 addr.sun_family = AF_UNIX; 1115 sun_len = offsetof(struct sockaddr_un, sun_path) + 1116 strlen(options.control_path) + 1; 1117 1118 if (strlcpy(addr.sun_path, options.control_path, 1119 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) { 1120 error("ControlPath \"%s\" too long for Unix domain socket", 1121 options.control_path); 1122 goto disable_mux_master; 1123 } 1124 1125 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1126 fatal("%s socket(): %s", __func__, strerror(errno)); 1127 1128 old_umask = umask(0177); 1129 if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) { 1130 if (errno == EINVAL || errno == EADDRINUSE) { 1131 error("ControlSocket %s already exists, " 1132 "disabling multiplexing", options.control_path); 1133 disable_mux_master: 1134 if (muxserver_sock != -1) { 1135 close(muxserver_sock); 1136 muxserver_sock = -1; 1137 } 1138 xfree(options.control_path); 1139 options.control_path = NULL; 1140 options.control_master = SSHCTL_MASTER_NO; 1141 return; 1142 } else 1143 fatal("%s bind(): %s", __func__, strerror(errno)); 1144 } 1145 umask(old_umask); 1146 1147 if (listen(muxserver_sock, 64) == -1) 1148 fatal("%s listen(): %s", __func__, strerror(errno)); 1149 1150 /* Now atomically "move" the mux socket into position */ 1151 if (link(options.control_path, orig_control_path) != 0) { 1152 if (errno != EEXIST) { 1153 fatal("%s: link mux listener %s => %s: %s", __func__, 1154 options.control_path, orig_control_path, 1155 strerror(errno)); 1156 } 1157 error("ControlSocket %s already exists, disabling multiplexing", 1158 orig_control_path); 1159 xfree(orig_control_path); 1160 unlink(options.control_path); 1161 goto disable_mux_master; 1162 } 1163 unlink(options.control_path); 1164 xfree(options.control_path); 1165 options.control_path = orig_control_path; 1166 1167 set_nonblock(muxserver_sock); 1168 1169 mux_listener_channel = channel_new("mux listener", 1170 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1171 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1172 0, options.control_path, 1); 1173 mux_listener_channel->mux_rcb = mux_master_read_cb; 1174 debug3("%s: mux listener channel %d fd %d", __func__, 1175 mux_listener_channel->self, mux_listener_channel->sock); 1176 } 1177 1178 /* Callback on open confirmation in mux master for a mux client session. */ 1179 static void 1180 mux_session_confirm(int id, int success, void *arg) 1181 { 1182 struct mux_session_confirm_ctx *cctx = arg; 1183 const char *display; 1184 Channel *c, *cc; 1185 int i; 1186 Buffer reply; 1187 1188 if (cctx == NULL) 1189 fatal("%s: cctx == NULL", __func__); 1190 if ((c = channel_by_id(id)) == NULL) 1191 fatal("%s: no channel for id %d", __func__, id); 1192 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1193 fatal("%s: channel %d lacks control channel %d", __func__, 1194 id, c->ctl_chan); 1195 1196 if (!success) { 1197 debug3("%s: sending failure reply", __func__); 1198 /* prepare reply */ 1199 buffer_init(&reply); 1200 buffer_put_int(&reply, MUX_S_FAILURE); 1201 buffer_put_int(&reply, cctx->rid); 1202 buffer_put_cstring(&reply, "Session open refused by peer"); 1203 goto done; 1204 } 1205 1206 display = getenv("DISPLAY"); 1207 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1208 char *proto, *data; 1209 1210 /* Get reasonable local authentication information. */ 1211 client_x11_get_proto(display, options.xauth_location, 1212 options.forward_x11_trusted, options.forward_x11_timeout, 1213 &proto, &data); 1214 /* Request forwarding with authentication spoofing. */ 1215 debug("Requesting X11 forwarding with authentication " 1216 "spoofing."); 1217 x11_request_forwarding_with_spoofing(id, display, proto, 1218 data, 1); 1219 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1220 /* XXX exit_on_forward_failure */ 1221 } 1222 1223 if (cctx->want_agent_fwd && options.forward_agent) { 1224 debug("Requesting authentication agent forwarding."); 1225 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1226 packet_send(); 1227 } 1228 1229 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1230 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1231 1232 debug3("%s: sending success reply", __func__); 1233 /* prepare reply */ 1234 buffer_init(&reply); 1235 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1236 buffer_put_int(&reply, cctx->rid); 1237 buffer_put_int(&reply, c->self); 1238 1239 done: 1240 /* Send reply */ 1241 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1242 buffer_free(&reply); 1243 1244 if (cc->mux_pause <= 0) 1245 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1246 cc->mux_pause = 0; /* start processing messages again */ 1247 c->open_confirm_ctx = NULL; 1248 buffer_free(&cctx->cmd); 1249 xfree(cctx->term); 1250 if (cctx->env != NULL) { 1251 for (i = 0; cctx->env[i] != NULL; i++) 1252 xfree(cctx->env[i]); 1253 xfree(cctx->env); 1254 } 1255 xfree(cctx); 1256 } 1257 1258 /* ** Multiplexing client support */ 1259 1260 /* Exit signal handler */ 1261 static void 1262 control_client_sighandler(int signo) 1263 { 1264 muxclient_terminate = signo; 1265 } 1266 1267 /* 1268 * Relay signal handler - used to pass some signals from mux client to 1269 * mux master. 1270 */ 1271 static void 1272 control_client_sigrelay(int signo) 1273 { 1274 int save_errno = errno; 1275 1276 if (muxserver_pid > 1) 1277 kill(muxserver_pid, signo); 1278 1279 errno = save_errno; 1280 } 1281 1282 static int 1283 mux_client_read(int fd, Buffer *b, u_int need) 1284 { 1285 u_int have; 1286 ssize_t len; 1287 u_char *p; 1288 struct pollfd pfd; 1289 1290 pfd.fd = fd; 1291 pfd.events = POLLIN; 1292 p = buffer_append_space(b, need); 1293 for (have = 0; have < need; ) { 1294 if (muxclient_terminate) { 1295 errno = EINTR; 1296 return -1; 1297 } 1298 len = read(fd, p + have, need - have); 1299 if (len < 0) { 1300 switch (errno) { 1301 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1302 case EWOULDBLOCK: 1303 #endif 1304 case EAGAIN: 1305 (void)poll(&pfd, 1, -1); 1306 /* FALLTHROUGH */ 1307 case EINTR: 1308 continue; 1309 default: 1310 return -1; 1311 } 1312 } 1313 if (len == 0) { 1314 errno = EPIPE; 1315 return -1; 1316 } 1317 have += (u_int)len; 1318 } 1319 return 0; 1320 } 1321 1322 static int 1323 mux_client_write_packet(int fd, Buffer *m) 1324 { 1325 Buffer queue; 1326 u_int have, need; 1327 int oerrno, len; 1328 u_char *ptr; 1329 struct pollfd pfd; 1330 1331 pfd.fd = fd; 1332 pfd.events = POLLOUT; 1333 buffer_init(&queue); 1334 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1335 1336 need = buffer_len(&queue); 1337 ptr = buffer_ptr(&queue); 1338 1339 for (have = 0; have < need; ) { 1340 if (muxclient_terminate) { 1341 buffer_free(&queue); 1342 errno = EINTR; 1343 return -1; 1344 } 1345 len = write(fd, ptr + have, need - have); 1346 if (len < 0) { 1347 switch (errno) { 1348 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1349 case EWOULDBLOCK: 1350 #endif 1351 case EAGAIN: 1352 (void)poll(&pfd, 1, -1); 1353 /* FALLTHROUGH */ 1354 case EINTR: 1355 continue; 1356 default: 1357 oerrno = errno; 1358 buffer_free(&queue); 1359 errno = oerrno; 1360 return -1; 1361 } 1362 } 1363 if (len == 0) { 1364 buffer_free(&queue); 1365 errno = EPIPE; 1366 return -1; 1367 } 1368 have += (u_int)len; 1369 } 1370 buffer_free(&queue); 1371 return 0; 1372 } 1373 1374 static int 1375 mux_client_read_packet(int fd, Buffer *m) 1376 { 1377 Buffer queue; 1378 u_int need, have; 1379 void *ptr; 1380 int oerrno; 1381 1382 buffer_init(&queue); 1383 if (mux_client_read(fd, &queue, 4) != 0) { 1384 if ((oerrno = errno) == EPIPE) 1385 debug3("%s: read header failed: %s", __func__, strerror(errno)); 1386 errno = oerrno; 1387 return -1; 1388 } 1389 need = get_u32(buffer_ptr(&queue)); 1390 if (mux_client_read(fd, &queue, need) != 0) { 1391 oerrno = errno; 1392 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1393 errno = oerrno; 1394 return -1; 1395 } 1396 ptr = buffer_get_string_ptr(&queue, &have); 1397 buffer_append(m, ptr, have); 1398 buffer_free(&queue); 1399 return 0; 1400 } 1401 1402 static int 1403 mux_client_hello_exchange(int fd) 1404 { 1405 Buffer m; 1406 u_int type, ver; 1407 1408 buffer_init(&m); 1409 buffer_put_int(&m, MUX_MSG_HELLO); 1410 buffer_put_int(&m, SSHMUX_VER); 1411 /* no extensions */ 1412 1413 if (mux_client_write_packet(fd, &m) != 0) 1414 fatal("%s: write packet: %s", __func__, strerror(errno)); 1415 1416 buffer_clear(&m); 1417 1418 /* Read their HELLO */ 1419 if (mux_client_read_packet(fd, &m) != 0) { 1420 buffer_free(&m); 1421 return -1; 1422 } 1423 1424 type = buffer_get_int(&m); 1425 if (type != MUX_MSG_HELLO) 1426 fatal("%s: expected HELLO (%u) received %u", 1427 __func__, MUX_MSG_HELLO, type); 1428 ver = buffer_get_int(&m); 1429 if (ver != SSHMUX_VER) 1430 fatal("Unsupported multiplexing protocol version %d " 1431 "(expected %d)", ver, SSHMUX_VER); 1432 debug2("%s: master version %u", __func__, ver); 1433 /* No extensions are presently defined */ 1434 while (buffer_len(&m) > 0) { 1435 char *name = buffer_get_string(&m, NULL); 1436 char *value = buffer_get_string(&m, NULL); 1437 1438 debug2("Unrecognised master extension \"%s\"", name); 1439 xfree(name); 1440 xfree(value); 1441 } 1442 buffer_free(&m); 1443 return 0; 1444 } 1445 1446 static u_int 1447 mux_client_request_alive(int fd) 1448 { 1449 Buffer m; 1450 char *e; 1451 u_int pid, type, rid; 1452 1453 debug3("%s: entering", __func__); 1454 1455 buffer_init(&m); 1456 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1457 buffer_put_int(&m, muxclient_request_id); 1458 1459 if (mux_client_write_packet(fd, &m) != 0) 1460 fatal("%s: write packet: %s", __func__, strerror(errno)); 1461 1462 buffer_clear(&m); 1463 1464 /* Read their reply */ 1465 if (mux_client_read_packet(fd, &m) != 0) { 1466 buffer_free(&m); 1467 return 0; 1468 } 1469 1470 type = buffer_get_int(&m); 1471 if (type != MUX_S_ALIVE) { 1472 e = buffer_get_string(&m, NULL); 1473 fatal("%s: master returned error: %s", __func__, e); 1474 } 1475 1476 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1477 fatal("%s: out of sequence reply: my id %u theirs %u", 1478 __func__, muxclient_request_id, rid); 1479 pid = buffer_get_int(&m); 1480 buffer_free(&m); 1481 1482 debug3("%s: done pid = %u", __func__, pid); 1483 1484 muxclient_request_id++; 1485 1486 return pid; 1487 } 1488 1489 static void 1490 mux_client_request_terminate(int fd) 1491 { 1492 Buffer m; 1493 char *e; 1494 u_int type, rid; 1495 1496 debug3("%s: entering", __func__); 1497 1498 buffer_init(&m); 1499 buffer_put_int(&m, MUX_C_TERMINATE); 1500 buffer_put_int(&m, muxclient_request_id); 1501 1502 if (mux_client_write_packet(fd, &m) != 0) 1503 fatal("%s: write packet: %s", __func__, strerror(errno)); 1504 1505 buffer_clear(&m); 1506 1507 /* Read their reply */ 1508 if (mux_client_read_packet(fd, &m) != 0) { 1509 /* Remote end exited already */ 1510 if (errno == EPIPE) { 1511 buffer_free(&m); 1512 return; 1513 } 1514 fatal("%s: read from master failed: %s", 1515 __func__, strerror(errno)); 1516 } 1517 1518 type = buffer_get_int(&m); 1519 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1520 fatal("%s: out of sequence reply: my id %u theirs %u", 1521 __func__, muxclient_request_id, rid); 1522 switch (type) { 1523 case MUX_S_OK: 1524 break; 1525 case MUX_S_PERMISSION_DENIED: 1526 e = buffer_get_string(&m, NULL); 1527 fatal("Master refused termination request: %s", e); 1528 case MUX_S_FAILURE: 1529 e = buffer_get_string(&m, NULL); 1530 fatal("%s: termination request failed: %s", __func__, e); 1531 default: 1532 fatal("%s: unexpected response from master 0x%08x", 1533 __func__, type); 1534 } 1535 buffer_free(&m); 1536 muxclient_request_id++; 1537 } 1538 1539 static int 1540 mux_client_request_forward(int fd, u_int ftype, Forward *fwd) 1541 { 1542 Buffer m; 1543 char *e, *fwd_desc; 1544 u_int type, rid; 1545 1546 fwd_desc = format_forward(ftype, fwd); 1547 debug("Requesting %s", fwd_desc); 1548 xfree(fwd_desc); 1549 1550 buffer_init(&m); 1551 buffer_put_int(&m, MUX_C_OPEN_FWD); 1552 buffer_put_int(&m, muxclient_request_id); 1553 buffer_put_int(&m, ftype); 1554 buffer_put_cstring(&m, 1555 fwd->listen_host == NULL ? "" : fwd->listen_host); 1556 buffer_put_int(&m, fwd->listen_port); 1557 buffer_put_cstring(&m, 1558 fwd->connect_host == NULL ? "" : fwd->connect_host); 1559 buffer_put_int(&m, fwd->connect_port); 1560 1561 if (mux_client_write_packet(fd, &m) != 0) 1562 fatal("%s: write packet: %s", __func__, strerror(errno)); 1563 1564 buffer_clear(&m); 1565 1566 /* Read their reply */ 1567 if (mux_client_read_packet(fd, &m) != 0) { 1568 buffer_free(&m); 1569 return -1; 1570 } 1571 1572 type = buffer_get_int(&m); 1573 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1574 fatal("%s: out of sequence reply: my id %u theirs %u", 1575 __func__, muxclient_request_id, rid); 1576 switch (type) { 1577 case MUX_S_OK: 1578 break; 1579 case MUX_S_REMOTE_PORT: 1580 fwd->allocated_port = buffer_get_int(&m); 1581 logit("Allocated port %u for remote forward to %s:%d", 1582 fwd->allocated_port, 1583 fwd->connect_host ? fwd->connect_host : "", 1584 fwd->connect_port); 1585 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1586 fprintf(stdout, "%u\n", fwd->allocated_port); 1587 break; 1588 case MUX_S_PERMISSION_DENIED: 1589 e = buffer_get_string(&m, NULL); 1590 buffer_free(&m); 1591 error("Master refused forwarding request: %s", e); 1592 return -1; 1593 case MUX_S_FAILURE: 1594 e = buffer_get_string(&m, NULL); 1595 buffer_free(&m); 1596 error("%s: forwarding request failed: %s", __func__, e); 1597 return -1; 1598 default: 1599 fatal("%s: unexpected response from master 0x%08x", 1600 __func__, type); 1601 } 1602 buffer_free(&m); 1603 1604 muxclient_request_id++; 1605 return 0; 1606 } 1607 1608 static int 1609 mux_client_request_forwards(int fd) 1610 { 1611 int i; 1612 1613 debug3("%s: requesting forwardings: %d local, %d remote", __func__, 1614 options.num_local_forwards, options.num_remote_forwards); 1615 1616 /* XXX ExitOnForwardingFailure */ 1617 for (i = 0; i < options.num_local_forwards; i++) { 1618 if (mux_client_request_forward(fd, 1619 options.local_forwards[i].connect_port == 0 ? 1620 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1621 options.local_forwards + i) != 0) 1622 return -1; 1623 } 1624 for (i = 0; i < options.num_remote_forwards; i++) { 1625 if (mux_client_request_forward(fd, MUX_FWD_REMOTE, 1626 options.remote_forwards + i) != 0) 1627 return -1; 1628 } 1629 return 0; 1630 } 1631 1632 static int 1633 mux_client_request_session(int fd) 1634 { 1635 Buffer m; 1636 char *e, *term; 1637 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1638 extern char **environ; 1639 int devnull, rawmode; 1640 1641 debug3("%s: entering", __func__); 1642 1643 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1644 error("%s: master alive request failed", __func__); 1645 return -1; 1646 } 1647 1648 signal(SIGPIPE, SIG_IGN); 1649 1650 if (stdin_null_flag) { 1651 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1652 fatal("open(/dev/null): %s", strerror(errno)); 1653 if (dup2(devnull, STDIN_FILENO) == -1) 1654 fatal("dup2: %s", strerror(errno)); 1655 if (devnull > STDERR_FILENO) 1656 close(devnull); 1657 } 1658 1659 term = getenv("TERM"); 1660 1661 buffer_init(&m); 1662 buffer_put_int(&m, MUX_C_NEW_SESSION); 1663 buffer_put_int(&m, muxclient_request_id); 1664 buffer_put_cstring(&m, ""); /* reserved */ 1665 buffer_put_int(&m, tty_flag); 1666 buffer_put_int(&m, options.forward_x11); 1667 buffer_put_int(&m, options.forward_agent); 1668 buffer_put_int(&m, subsystem_flag); 1669 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1670 0xffffffff : (u_int)options.escape_char); 1671 buffer_put_cstring(&m, term == NULL ? "" : term); 1672 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1673 1674 if (options.num_send_env > 0 && environ != NULL) { 1675 /* Pass environment */ 1676 for (i = 0; environ[i] != NULL; i++) { 1677 if (env_permitted(environ[i])) { 1678 buffer_put_cstring(&m, environ[i]); 1679 } 1680 } 1681 } 1682 1683 if (mux_client_write_packet(fd, &m) != 0) 1684 fatal("%s: write packet: %s", __func__, strerror(errno)); 1685 1686 /* Send the stdio file descriptors */ 1687 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1688 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1689 mm_send_fd(fd, STDERR_FILENO) == -1) 1690 fatal("%s: send fds failed", __func__); 1691 1692 debug3("%s: session request sent", __func__); 1693 1694 /* Read their reply */ 1695 buffer_clear(&m); 1696 if (mux_client_read_packet(fd, &m) != 0) { 1697 error("%s: read from master failed: %s", 1698 __func__, strerror(errno)); 1699 buffer_free(&m); 1700 return -1; 1701 } 1702 1703 type = buffer_get_int(&m); 1704 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1705 fatal("%s: out of sequence reply: my id %u theirs %u", 1706 __func__, muxclient_request_id, rid); 1707 switch (type) { 1708 case MUX_S_SESSION_OPENED: 1709 sid = buffer_get_int(&m); 1710 debug("%s: master session id: %u", __func__, sid); 1711 break; 1712 case MUX_S_PERMISSION_DENIED: 1713 e = buffer_get_string(&m, NULL); 1714 buffer_free(&m); 1715 error("Master refused session request: %s", e); 1716 return -1; 1717 case MUX_S_FAILURE: 1718 e = buffer_get_string(&m, NULL); 1719 buffer_free(&m); 1720 error("%s: session request failed: %s", __func__, e); 1721 return -1; 1722 default: 1723 buffer_free(&m); 1724 error("%s: unexpected response from master 0x%08x", 1725 __func__, type); 1726 return -1; 1727 } 1728 muxclient_request_id++; 1729 1730 signal(SIGHUP, control_client_sighandler); 1731 signal(SIGINT, control_client_sighandler); 1732 signal(SIGTERM, control_client_sighandler); 1733 signal(SIGWINCH, control_client_sigrelay); 1734 1735 rawmode = tty_flag; 1736 if (tty_flag) 1737 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1738 1739 /* 1740 * Stick around until the controlee closes the client_fd. 1741 * Before it does, it is expected to write an exit message. 1742 * This process must read the value and wait for the closure of 1743 * the client_fd; if this one closes early, the multiplex master will 1744 * terminate early too (possibly losing data). 1745 */ 1746 for (exitval = 255, exitval_seen = 0;;) { 1747 buffer_clear(&m); 1748 if (mux_client_read_packet(fd, &m) != 0) 1749 break; 1750 type = buffer_get_int(&m); 1751 switch (type) { 1752 case MUX_S_TTY_ALLOC_FAIL: 1753 if ((esid = buffer_get_int(&m)) != sid) 1754 fatal("%s: tty alloc fail on unknown session: " 1755 "my id %u theirs %u", 1756 __func__, sid, esid); 1757 leave_raw_mode(options.request_tty == 1758 REQUEST_TTY_FORCE); 1759 rawmode = 0; 1760 continue; 1761 case MUX_S_EXIT_MESSAGE: 1762 if ((esid = buffer_get_int(&m)) != sid) 1763 fatal("%s: exit on unknown session: " 1764 "my id %u theirs %u", 1765 __func__, sid, esid); 1766 if (exitval_seen) 1767 fatal("%s: exitval sent twice", __func__); 1768 exitval = buffer_get_int(&m); 1769 exitval_seen = 1; 1770 continue; 1771 default: 1772 e = buffer_get_string(&m, NULL); 1773 fatal("%s: master returned error: %s", __func__, e); 1774 } 1775 } 1776 1777 close(fd); 1778 if (rawmode) 1779 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1780 1781 if (muxclient_terminate) { 1782 debug2("Exiting on signal %d", muxclient_terminate); 1783 exitval = 255; 1784 } else if (!exitval_seen) { 1785 debug2("Control master terminated unexpectedly"); 1786 exitval = 255; 1787 } else 1788 debug2("Received exit status from master %d", exitval); 1789 1790 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1791 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1792 1793 exit(exitval); 1794 } 1795 1796 static int 1797 mux_client_request_stdio_fwd(int fd) 1798 { 1799 Buffer m; 1800 char *e; 1801 u_int type, rid, sid; 1802 int devnull; 1803 1804 debug3("%s: entering", __func__); 1805 1806 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1807 error("%s: master alive request failed", __func__); 1808 return -1; 1809 } 1810 1811 signal(SIGPIPE, SIG_IGN); 1812 1813 if (stdin_null_flag) { 1814 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1815 fatal("open(/dev/null): %s", strerror(errno)); 1816 if (dup2(devnull, STDIN_FILENO) == -1) 1817 fatal("dup2: %s", strerror(errno)); 1818 if (devnull > STDERR_FILENO) 1819 close(devnull); 1820 } 1821 1822 buffer_init(&m); 1823 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1824 buffer_put_int(&m, muxclient_request_id); 1825 buffer_put_cstring(&m, ""); /* reserved */ 1826 buffer_put_cstring(&m, stdio_forward_host); 1827 buffer_put_int(&m, stdio_forward_port); 1828 1829 if (mux_client_write_packet(fd, &m) != 0) 1830 fatal("%s: write packet: %s", __func__, strerror(errno)); 1831 1832 /* Send the stdio file descriptors */ 1833 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1834 mm_send_fd(fd, STDOUT_FILENO) == -1) 1835 fatal("%s: send fds failed", __func__); 1836 1837 debug3("%s: stdio forward request sent", __func__); 1838 1839 /* Read their reply */ 1840 buffer_clear(&m); 1841 1842 if (mux_client_read_packet(fd, &m) != 0) { 1843 error("%s: read from master failed: %s", 1844 __func__, strerror(errno)); 1845 buffer_free(&m); 1846 return -1; 1847 } 1848 1849 type = buffer_get_int(&m); 1850 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1851 fatal("%s: out of sequence reply: my id %u theirs %u", 1852 __func__, muxclient_request_id, rid); 1853 switch (type) { 1854 case MUX_S_SESSION_OPENED: 1855 sid = buffer_get_int(&m); 1856 debug("%s: master session id: %u", __func__, sid); 1857 break; 1858 case MUX_S_PERMISSION_DENIED: 1859 e = buffer_get_string(&m, NULL); 1860 buffer_free(&m); 1861 fatal("Master refused stdio forwarding request: %s", e); 1862 case MUX_S_FAILURE: 1863 e = buffer_get_string(&m, NULL); 1864 buffer_free(&m); 1865 fatal("%s: stdio forwarding request failed: %s", __func__, e); 1866 default: 1867 buffer_free(&m); 1868 error("%s: unexpected response from master 0x%08x", 1869 __func__, type); 1870 return -1; 1871 } 1872 muxclient_request_id++; 1873 1874 signal(SIGHUP, control_client_sighandler); 1875 signal(SIGINT, control_client_sighandler); 1876 signal(SIGTERM, control_client_sighandler); 1877 signal(SIGWINCH, control_client_sigrelay); 1878 1879 /* 1880 * Stick around until the controlee closes the client_fd. 1881 */ 1882 buffer_clear(&m); 1883 if (mux_client_read_packet(fd, &m) != 0) { 1884 if (errno == EPIPE || 1885 (errno == EINTR && muxclient_terminate != 0)) 1886 return 0; 1887 fatal("%s: mux_client_read_packet: %s", 1888 __func__, strerror(errno)); 1889 } 1890 fatal("%s: master returned unexpected message %u", __func__, type); 1891 } 1892 1893 static void 1894 mux_client_request_stop_listening(int fd) 1895 { 1896 Buffer m; 1897 char *e; 1898 u_int type, rid; 1899 1900 debug3("%s: entering", __func__); 1901 1902 buffer_init(&m); 1903 buffer_put_int(&m, MUX_C_STOP_LISTENING); 1904 buffer_put_int(&m, muxclient_request_id); 1905 1906 if (mux_client_write_packet(fd, &m) != 0) 1907 fatal("%s: write packet: %s", __func__, strerror(errno)); 1908 1909 buffer_clear(&m); 1910 1911 /* Read their reply */ 1912 if (mux_client_read_packet(fd, &m) != 0) 1913 fatal("%s: read from master failed: %s", 1914 __func__, strerror(errno)); 1915 1916 type = buffer_get_int(&m); 1917 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1918 fatal("%s: out of sequence reply: my id %u theirs %u", 1919 __func__, muxclient_request_id, rid); 1920 switch (type) { 1921 case MUX_S_OK: 1922 break; 1923 case MUX_S_PERMISSION_DENIED: 1924 e = buffer_get_string(&m, NULL); 1925 fatal("Master refused stop listening request: %s", e); 1926 case MUX_S_FAILURE: 1927 e = buffer_get_string(&m, NULL); 1928 fatal("%s: stop listening request failed: %s", __func__, e); 1929 default: 1930 fatal("%s: unexpected response from master 0x%08x", 1931 __func__, type); 1932 } 1933 buffer_free(&m); 1934 muxclient_request_id++; 1935 } 1936 1937 /* Multiplex client main loop. */ 1938 void 1939 muxclient(const char *path) 1940 { 1941 struct sockaddr_un addr; 1942 socklen_t sun_len; 1943 int sock; 1944 u_int pid; 1945 1946 if (muxclient_command == 0) { 1947 if (stdio_forward_host != NULL) 1948 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 1949 else 1950 muxclient_command = SSHMUX_COMMAND_OPEN; 1951 } 1952 1953 switch (options.control_master) { 1954 case SSHCTL_MASTER_AUTO: 1955 case SSHCTL_MASTER_AUTO_ASK: 1956 debug("auto-mux: Trying existing master"); 1957 /* FALLTHROUGH */ 1958 case SSHCTL_MASTER_NO: 1959 break; 1960 default: 1961 return; 1962 } 1963 1964 memset(&addr, '\0', sizeof(addr)); 1965 addr.sun_family = AF_UNIX; 1966 sun_len = offsetof(struct sockaddr_un, sun_path) + 1967 strlen(path) + 1; 1968 1969 if (strlcpy(addr.sun_path, path, 1970 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 1971 fatal("ControlPath too long"); 1972 1973 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1974 fatal("%s socket(): %s", __func__, strerror(errno)); 1975 1976 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 1977 switch (muxclient_command) { 1978 case SSHMUX_COMMAND_OPEN: 1979 case SSHMUX_COMMAND_STDIO_FWD: 1980 break; 1981 default: 1982 fatal("Control socket connect(%.100s): %s", path, 1983 strerror(errno)); 1984 } 1985 if (errno == ECONNREFUSED && 1986 options.control_master != SSHCTL_MASTER_NO) { 1987 debug("Stale control socket %.100s, unlinking", path); 1988 unlink(path); 1989 } else if (errno == ENOENT) { 1990 debug("Control socket \"%.100s\" does not exist", path); 1991 } else { 1992 error("Control socket connect(%.100s): %s", path, 1993 strerror(errno)); 1994 } 1995 close(sock); 1996 return; 1997 } 1998 set_nonblock(sock); 1999 2000 if (mux_client_hello_exchange(sock) != 0) { 2001 error("%s: master hello exchange failed", __func__); 2002 close(sock); 2003 return; 2004 } 2005 2006 switch (muxclient_command) { 2007 case SSHMUX_COMMAND_ALIVE_CHECK: 2008 if ((pid = mux_client_request_alive(sock)) == 0) 2009 fatal("%s: master alive check failed", __func__); 2010 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2011 exit(0); 2012 case SSHMUX_COMMAND_TERMINATE: 2013 mux_client_request_terminate(sock); 2014 fprintf(stderr, "Exit request sent.\r\n"); 2015 exit(0); 2016 case SSHMUX_COMMAND_FORWARD: 2017 if (mux_client_request_forwards(sock) != 0) 2018 fatal("%s: master forward request failed", __func__); 2019 exit(0); 2020 case SSHMUX_COMMAND_OPEN: 2021 if (mux_client_request_forwards(sock) != 0) { 2022 error("%s: master forward request failed", __func__); 2023 return; 2024 } 2025 mux_client_request_session(sock); 2026 return; 2027 case SSHMUX_COMMAND_STDIO_FWD: 2028 mux_client_request_stdio_fwd(sock); 2029 exit(0); 2030 case SSHMUX_COMMAND_STOP: 2031 mux_client_request_stop_listening(sock); 2032 fprintf(stderr, "Stop listening request sent.\r\n"); 2033 exit(0); 2034 default: 2035 fatal("unrecognised muxclient_command %d", muxclient_command); 2036 } 2037 } 2038