1/* $OpenBSD: mux.c,v 1.44 2013/07/12 00:19:58 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#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 "buffer.h" 75#include "channels.h" 76#include "msg.h" 77#include "packet.h" 78#include "monitor_fdpass.h" 79#include "sshpty.h" 80#include "key.h" 81#include "readconf.h" 82#include "clientloop.h" 83 84/* from ssh.c */ 85extern int tty_flag; 86extern Options options; 87extern int stdin_null_flag; 88extern char *host; 89extern int subsystem_flag; 90extern Buffer command; 91extern volatile sig_atomic_t quit_pending; 92extern char *stdio_forward_host; 93extern int stdio_forward_port; 94 95/* Context for session open confirmation callback */ 96struct mux_session_confirm_ctx { 97 u_int want_tty; 98 u_int want_subsys; 99 u_int want_x_fwd; 100 u_int want_agent_fwd; 101 Buffer cmd; 102 char *term; 103 struct termios tio; 104 char **env; 105 u_int rid; 106}; 107 108/* Context for global channel callback */ 109struct mux_channel_confirm_ctx { 110 u_int cid; /* channel id */ 111 u_int rid; /* request id */ 112 int fid; /* forward id */ 113}; 114 115/* fd to control socket */ 116int muxserver_sock = -1; 117 118/* client request id */ 119u_int muxclient_request_id = 0; 120 121/* Multiplexing control command */ 122u_int muxclient_command = 0; 123 124/* Set when signalled. */ 125static volatile sig_atomic_t muxclient_terminate = 0; 126 127/* PID of multiplex server */ 128static u_int muxserver_pid = 0; 129 130static Channel *mux_listener_channel = NULL; 131 132struct mux_master_state { 133 int hello_rcvd; 134}; 135 136/* mux protocol messages */ 137#define MUX_MSG_HELLO 0x00000001 138#define MUX_C_NEW_SESSION 0x10000002 139#define MUX_C_ALIVE_CHECK 0x10000004 140#define MUX_C_TERMINATE 0x10000005 141#define MUX_C_OPEN_FWD 0x10000006 142#define MUX_C_CLOSE_FWD 0x10000007 143#define MUX_C_NEW_STDIO_FWD 0x10000008 144#define MUX_C_STOP_LISTENING 0x10000009 145#define MUX_S_OK 0x80000001 146#define MUX_S_PERMISSION_DENIED 0x80000002 147#define MUX_S_FAILURE 0x80000003 148#define MUX_S_EXIT_MESSAGE 0x80000004 149#define MUX_S_ALIVE 0x80000005 150#define MUX_S_SESSION_OPENED 0x80000006 151#define MUX_S_REMOTE_PORT 0x80000007 152#define MUX_S_TTY_ALLOC_FAIL 0x80000008 153 154/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 155#define MUX_FWD_LOCAL 1 156#define MUX_FWD_REMOTE 2 157#define MUX_FWD_DYNAMIC 3 158 159static void mux_session_confirm(int, int, void *); 160 161static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 162static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 163static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 164static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 165static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 166static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 167static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 168static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 169 170static const struct { 171 u_int type; 172 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 173} mux_master_handlers[] = { 174 { MUX_MSG_HELLO, process_mux_master_hello }, 175 { MUX_C_NEW_SESSION, process_mux_new_session }, 176 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 177 { MUX_C_TERMINATE, process_mux_terminate }, 178 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 179 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 180 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 181 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 182 { 0, NULL } 183}; 184 185/* Cleanup callback fired on closure of mux slave _session_ channel */ 186/* ARGSUSED */ 187static void 188mux_master_session_cleanup_cb(int cid, void *unused) 189{ 190 Channel *cc, *c = channel_by_id(cid); 191 192 debug3("%s: entering for channel %d", __func__, cid); 193 if (c == NULL) 194 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 195 if (c->ctl_chan != -1) { 196 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 197 fatal("%s: channel %d missing control channel %d", 198 __func__, c->self, c->ctl_chan); 199 c->ctl_chan = -1; 200 cc->remote_id = -1; 201 chan_rcvd_oclose(cc); 202 } 203 channel_cancel_cleanup(c->self); 204} 205 206/* Cleanup callback fired on closure of mux slave _control_ channel */ 207/* ARGSUSED */ 208static void 209mux_master_control_cleanup_cb(int cid, void *unused) 210{ 211 Channel *sc, *c = channel_by_id(cid); 212 213 debug3("%s: entering for channel %d", __func__, cid); 214 if (c == NULL) 215 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 216 if (c->remote_id != -1) { 217 if ((sc = channel_by_id(c->remote_id)) == NULL) 218 fatal("%s: channel %d missing session channel %d", 219 __func__, c->self, c->remote_id); 220 c->remote_id = -1; 221 sc->ctl_chan = -1; 222 if (sc->type != SSH_CHANNEL_OPEN && 223 sc->type != SSH_CHANNEL_OPENING) { 224 debug2("%s: channel %d: not open", __func__, sc->self); 225 chan_mark_dead(sc); 226 } else { 227 if (sc->istate == CHAN_INPUT_OPEN) 228 chan_read_failed(sc); 229 if (sc->ostate == CHAN_OUTPUT_OPEN) 230 chan_write_failed(sc); 231 } 232 } 233 channel_cancel_cleanup(c->self); 234} 235 236/* Check mux client environment variables before passing them to mux master. */ 237static int 238env_permitted(char *env) 239{ 240 int i, ret; 241 char name[1024], *cp; 242 243 if ((cp = strchr(env, '=')) == NULL || cp == env) 244 return 0; 245 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 246 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 247 error("env_permitted: name '%.100s...' too long", env); 248 return 0; 249 } 250 251 for (i = 0; i < options.num_send_env; i++) 252 if (match_pattern(name, options.send_env[i])) 253 return 1; 254 255 return 0; 256} 257 258/* Mux master protocol message handlers */ 259 260static int 261process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 262{ 263 u_int ver; 264 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 265 266 if (state == NULL) 267 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 268 if (state->hello_rcvd) { 269 error("%s: HELLO received twice", __func__); 270 return -1; 271 } 272 if (buffer_get_int_ret(&ver, m) != 0) { 273 malf: 274 error("%s: malformed message", __func__); 275 return -1; 276 } 277 if (ver != SSHMUX_VER) { 278 error("Unsupported multiplexing protocol version %d " 279 "(expected %d)", ver, SSHMUX_VER); 280 return -1; 281 } 282 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 283 284 /* No extensions are presently defined */ 285 while (buffer_len(m) > 0) { 286 char *name = buffer_get_string_ret(m, NULL); 287 char *value = buffer_get_string_ret(m, NULL); 288 289 if (name == NULL || value == NULL) { 290 free(name); 291 free(value); 292 goto malf; 293 } 294 debug2("Unrecognised slave extension \"%s\"", name); 295 free(name); 296 free(value); 297 } 298 state->hello_rcvd = 1; 299 return 0; 300} 301 302static int 303process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 304{ 305 Channel *nc; 306 struct mux_session_confirm_ctx *cctx; 307 char *reserved, *cmd, *cp; 308 u_int i, j, len, env_len, escape_char, window, packetmax; 309 int new_fd[3]; 310 311 /* Reply for SSHMUX_COMMAND_OPEN */ 312 cctx = xcalloc(1, sizeof(*cctx)); 313 cctx->term = NULL; 314 cctx->rid = rid; 315 cmd = reserved = NULL; 316 cctx->env = NULL; 317 env_len = 0; 318 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 319 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 320 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 321 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 322 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 323 buffer_get_int_ret(&escape_char, m) != 0 || 324 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 325 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 326 malf: 327 free(cmd); 328 free(reserved); 329 for (j = 0; j < env_len; j++) 330 free(cctx->env[j]); 331 free(cctx->env); 332 free(cctx->term); 333 free(cctx); 334 error("%s: malformed message", __func__); 335 return -1; 336 } 337 free(reserved); 338 reserved = NULL; 339 340 while (buffer_len(m) > 0) { 341#define MUX_MAX_ENV_VARS 4096 342 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 343 goto malf; 344 if (!env_permitted(cp)) { 345 free(cp); 346 continue; 347 } 348 cctx->env = xrealloc(cctx->env, env_len + 2, 349 sizeof(*cctx->env)); 350 cctx->env[env_len++] = cp; 351 cctx->env[env_len] = NULL; 352 if (env_len > MUX_MAX_ENV_VARS) { 353 error(">%d environment variables received, ignoring " 354 "additional", MUX_MAX_ENV_VARS); 355 break; 356 } 357 } 358 359 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 360 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 361 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 362 cctx->want_subsys, cctx->term, cmd, env_len); 363 364 buffer_init(&cctx->cmd); 365 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 366 free(cmd); 367 cmd = NULL; 368 369 /* Gather fds from client */ 370 for(i = 0; i < 3; i++) { 371 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 372 error("%s: failed to receive fd %d from slave", 373 __func__, i); 374 for (j = 0; j < i; j++) 375 close(new_fd[j]); 376 for (j = 0; j < env_len; j++) 377 free(cctx->env[j]); 378 free(cctx->env); 379 free(cctx->term); 380 buffer_free(&cctx->cmd); 381 free(cctx); 382 383 /* prepare reply */ 384 buffer_put_int(r, MUX_S_FAILURE); 385 buffer_put_int(r, rid); 386 buffer_put_cstring(r, 387 "did not receive file descriptors"); 388 return -1; 389 } 390 } 391 392 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 393 new_fd[0], new_fd[1], new_fd[2]); 394 395 /* XXX support multiple child sessions in future */ 396 if (c->remote_id != -1) { 397 debug2("%s: session already open", __func__); 398 /* prepare reply */ 399 buffer_put_int(r, MUX_S_FAILURE); 400 buffer_put_int(r, rid); 401 buffer_put_cstring(r, "Multiple sessions not supported"); 402 cleanup: 403 close(new_fd[0]); 404 close(new_fd[1]); 405 close(new_fd[2]); 406 free(cctx->term); 407 if (env_len != 0) { 408 for (i = 0; i < env_len; i++) 409 free(cctx->env[i]); 410 free(cctx->env); 411 } 412 buffer_free(&cctx->cmd); 413 free(cctx); 414 return 0; 415 } 416 417 if (options.control_master == SSHCTL_MASTER_ASK || 418 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 419 if (!ask_permission("Allow shared connection to %s? ", host)) { 420 debug2("%s: session refused by user", __func__); 421 /* prepare reply */ 422 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 423 buffer_put_int(r, rid); 424 buffer_put_cstring(r, "Permission denied"); 425 goto cleanup; 426 } 427 } 428 429 /* Try to pick up ttymodes from client before it goes raw */ 430 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 431 error("%s: tcgetattr: %s", __func__, strerror(errno)); 432 433 /* enable nonblocking unless tty */ 434 if (!isatty(new_fd[0])) 435 set_nonblock(new_fd[0]); 436 if (!isatty(new_fd[1])) 437 set_nonblock(new_fd[1]); 438 if (!isatty(new_fd[2])) 439 set_nonblock(new_fd[2]); 440 441 window = CHAN_SES_WINDOW_DEFAULT; 442 packetmax = CHAN_SES_PACKET_DEFAULT; 443 if (cctx->want_tty) { 444 window >>= 1; 445 packetmax >>= 1; 446 } 447 448 nc = channel_new("session", SSH_CHANNEL_OPENING, 449 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 450 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 451 452 nc->ctl_chan = c->self; /* link session -> control channel */ 453 c->remote_id = nc->self; /* link control -> session channel */ 454 455 if (cctx->want_tty && escape_char != 0xffffffff) { 456 channel_register_filter(nc->self, 457 client_simple_escape_filter, NULL, 458 client_filter_cleanup, 459 client_new_escape_filter_ctx((int)escape_char)); 460 } 461 462 debug2("%s: channel_new: %d linked to control channel %d", 463 __func__, nc->self, nc->ctl_chan); 464 465 channel_send_open(nc->self); 466 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 467 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 468 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 469 470 /* reply is deferred, sent by mux_session_confirm */ 471 return 0; 472} 473 474static int 475process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 476{ 477 debug2("%s: channel %d: alive check", __func__, c->self); 478 479 /* prepare reply */ 480 buffer_put_int(r, MUX_S_ALIVE); 481 buffer_put_int(r, rid); 482 buffer_put_int(r, (u_int)getpid()); 483 484 return 0; 485} 486 487static int 488process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 489{ 490 debug2("%s: channel %d: terminate request", __func__, c->self); 491 492 if (options.control_master == SSHCTL_MASTER_ASK || 493 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 494 if (!ask_permission("Terminate shared connection to %s? ", 495 host)) { 496 debug2("%s: termination refused by user", __func__); 497 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 498 buffer_put_int(r, rid); 499 buffer_put_cstring(r, "Permission denied"); 500 return 0; 501 } 502 } 503 504 quit_pending = 1; 505 buffer_put_int(r, MUX_S_OK); 506 buffer_put_int(r, rid); 507 /* XXX exit happens too soon - message never makes it to client */ 508 return 0; 509} 510 511static char * 512format_forward(u_int ftype, Forward *fwd) 513{ 514 char *ret; 515 516 switch (ftype) { 517 case MUX_FWD_LOCAL: 518 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 519 (fwd->listen_host == NULL) ? 520 (options.gateway_ports ? "*" : "LOCALHOST") : 521 fwd->listen_host, fwd->listen_port, 522 fwd->connect_host, fwd->connect_port); 523 break; 524 case MUX_FWD_DYNAMIC: 525 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 526 (fwd->listen_host == NULL) ? 527 (options.gateway_ports ? "*" : "LOCALHOST") : 528 fwd->listen_host, fwd->listen_port); 529 break; 530 case MUX_FWD_REMOTE: 531 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 532 (fwd->listen_host == NULL) ? 533 "LOCALHOST" : fwd->listen_host, 534 fwd->listen_port, 535 fwd->connect_host, fwd->connect_port); 536 break; 537 default: 538 fatal("%s: unknown forward type %u", __func__, ftype); 539 } 540 return ret; 541} 542 543static int 544compare_host(const char *a, const char *b) 545{ 546 if (a == NULL && b == NULL) 547 return 1; 548 if (a == NULL || b == NULL) 549 return 0; 550 return strcmp(a, b) == 0; 551} 552 553static int 554compare_forward(Forward *a, Forward *b) 555{ 556 if (!compare_host(a->listen_host, b->listen_host)) 557 return 0; 558 if (a->listen_port != b->listen_port) 559 return 0; 560 if (!compare_host(a->connect_host, b->connect_host)) 561 return 0; 562 if (a->connect_port != b->connect_port) 563 return 0; 564 565 return 1; 566} 567 568static void 569mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 570{ 571 struct mux_channel_confirm_ctx *fctx = ctxt; 572 char *failmsg = NULL; 573 Forward *rfwd; 574 Channel *c; 575 Buffer out; 576 577 if ((c = channel_by_id(fctx->cid)) == NULL) { 578 /* no channel for reply */ 579 error("%s: unknown channel", __func__); 580 return; 581 } 582 buffer_init(&out); 583 if (fctx->fid >= options.num_remote_forwards) { 584 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 585 goto fail; 586 } 587 rfwd = &options.remote_forwards[fctx->fid]; 588 debug("%s: %s for: listen %d, connect %s:%d", __func__, 589 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 590 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); 591 if (type == SSH2_MSG_REQUEST_SUCCESS) { 592 if (rfwd->listen_port == 0) { 593 rfwd->allocated_port = packet_get_int(); 594 logit("Allocated port %u for mux remote forward" 595 " to %s:%d", rfwd->allocated_port, 596 rfwd->connect_host, rfwd->connect_port); 597 buffer_put_int(&out, MUX_S_REMOTE_PORT); 598 buffer_put_int(&out, fctx->rid); 599 buffer_put_int(&out, rfwd->allocated_port); 600 channel_update_permitted_opens(rfwd->handle, 601 rfwd->allocated_port); 602 } else { 603 buffer_put_int(&out, MUX_S_OK); 604 buffer_put_int(&out, fctx->rid); 605 } 606 goto out; 607 } else { 608 if (rfwd->listen_port == 0) 609 channel_update_permitted_opens(rfwd->handle, -1); 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 free(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 627static int 628process_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 u_int lport, cport; 634 int i, ret = 0, freefwd = 1; 635 636 fwd.listen_host = fwd.connect_host = NULL; 637 if (buffer_get_int_ret(&ftype, m) != 0 || 638 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 639 buffer_get_int_ret(&lport, m) != 0 || 640 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 641 buffer_get_int_ret(&cport, m) != 0 || 642 lport > 65535 || cport > 65535) { 643 error("%s: malformed message", __func__); 644 ret = -1; 645 goto out; 646 } 647 fwd.listen_port = lport; 648 fwd.connect_port = cport; 649 if (*fwd.listen_host == '\0') { 650 free(fwd.listen_host); 651 fwd.listen_host = NULL; 652 } 653 if (*fwd.connect_host == '\0') { 654 free(fwd.connect_host); 655 fwd.connect_host = NULL; 656 } 657 658 debug2("%s: channel %d: request %s", __func__, c->self, 659 (fwd_desc = format_forward(ftype, &fwd))); 660 661 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 662 ftype != MUX_FWD_DYNAMIC) { 663 logit("%s: invalid forwarding type %u", __func__, ftype); 664 invalid: 665 free(fwd.listen_host); 666 free(fwd.connect_host); 667 buffer_put_int(r, MUX_S_FAILURE); 668 buffer_put_int(r, rid); 669 buffer_put_cstring(r, "Invalid forwarding request"); 670 return 0; 671 } 672 if (fwd.listen_port >= 65536) { 673 logit("%s: invalid listen port %u", __func__, 674 fwd.listen_port); 675 goto invalid; 676 } 677 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC && 678 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 679 logit("%s: invalid connect port %u", __func__, 680 fwd.connect_port); 681 goto invalid; 682 } 683 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) { 684 logit("%s: missing connect host", __func__); 685 goto invalid; 686 } 687 688 /* Skip forwards that have already been requested */ 689 switch (ftype) { 690 case MUX_FWD_LOCAL: 691 case MUX_FWD_DYNAMIC: 692 for (i = 0; i < options.num_local_forwards; i++) { 693 if (compare_forward(&fwd, 694 options.local_forwards + i)) { 695 exists: 696 debug2("%s: found existing forwarding", 697 __func__); 698 buffer_put_int(r, MUX_S_OK); 699 buffer_put_int(r, rid); 700 goto out; 701 } 702 } 703 break; 704 case MUX_FWD_REMOTE: 705 for (i = 0; i < options.num_remote_forwards; i++) { 706 if (compare_forward(&fwd, 707 options.remote_forwards + i)) { 708 if (fwd.listen_port != 0) 709 goto exists; 710 debug2("%s: found allocated port", 711 __func__); 712 buffer_put_int(r, MUX_S_REMOTE_PORT); 713 buffer_put_int(r, rid); 714 buffer_put_int(r, 715 options.remote_forwards[i].allocated_port); 716 goto out; 717 } 718 } 719 break; 720 } 721 722 if (options.control_master == SSHCTL_MASTER_ASK || 723 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 724 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 725 debug2("%s: forwarding refused by user", __func__); 726 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 727 buffer_put_int(r, rid); 728 buffer_put_cstring(r, "Permission denied"); 729 goto out; 730 } 731 } 732 733 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 734 if (!channel_setup_local_fwd_listener(fwd.listen_host, 735 fwd.listen_port, fwd.connect_host, fwd.connect_port, 736 options.gateway_ports)) { 737 fail: 738 logit("slave-requested %s failed", fwd_desc); 739 buffer_put_int(r, MUX_S_FAILURE); 740 buffer_put_int(r, rid); 741 buffer_put_cstring(r, "Port forwarding failed"); 742 goto out; 743 } 744 add_local_forward(&options, &fwd); 745 freefwd = 0; 746 } else { 747 struct mux_channel_confirm_ctx *fctx; 748 749 fwd.handle = channel_request_remote_forwarding(fwd.listen_host, 750 fwd.listen_port, fwd.connect_host, fwd.connect_port); 751 if (fwd.handle < 0) 752 goto fail; 753 add_remote_forward(&options, &fwd); 754 fctx = xcalloc(1, sizeof(*fctx)); 755 fctx->cid = c->self; 756 fctx->rid = rid; 757 fctx->fid = options.num_remote_forwards - 1; 758 client_register_global_confirm(mux_confirm_remote_forward, 759 fctx); 760 freefwd = 0; 761 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 762 /* delayed reply in mux_confirm_remote_forward */ 763 goto out; 764 } 765 buffer_put_int(r, MUX_S_OK); 766 buffer_put_int(r, rid); 767 out: 768 free(fwd_desc); 769 if (freefwd) { 770 free(fwd.listen_host); 771 free(fwd.connect_host); 772 } 773 return ret; 774} 775 776static int 777process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 778{ 779 Forward fwd, *found_fwd; 780 char *fwd_desc = NULL; 781 const char *error_reason = NULL; 782 u_int ftype; 783 int i, listen_port, ret = 0; 784 u_int lport, cport; 785 786 fwd.listen_host = fwd.connect_host = NULL; 787 if (buffer_get_int_ret(&ftype, m) != 0 || 788 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 789 buffer_get_int_ret(&lport, m) != 0 || 790 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 791 buffer_get_int_ret(&cport, m) != 0 || 792 lport > 65535 || cport > 65535) { 793 error("%s: malformed message", __func__); 794 ret = -1; 795 goto out; 796 } 797 fwd.listen_port = lport; 798 fwd.connect_port = cport; 799 800 if (*fwd.listen_host == '\0') { 801 free(fwd.listen_host); 802 fwd.listen_host = NULL; 803 } 804 if (*fwd.connect_host == '\0') { 805 free(fwd.connect_host); 806 fwd.connect_host = NULL; 807 } 808 809 debug2("%s: channel %d: request cancel %s", __func__, c->self, 810 (fwd_desc = format_forward(ftype, &fwd))); 811 812 /* make sure this has been requested */ 813 found_fwd = NULL; 814 switch (ftype) { 815 case MUX_FWD_LOCAL: 816 case MUX_FWD_DYNAMIC: 817 for (i = 0; i < options.num_local_forwards; i++) { 818 if (compare_forward(&fwd, 819 options.local_forwards + i)) { 820 found_fwd = options.local_forwards + i; 821 break; 822 } 823 } 824 break; 825 case MUX_FWD_REMOTE: 826 for (i = 0; i < options.num_remote_forwards; i++) { 827 if (compare_forward(&fwd, 828 options.remote_forwards + i)) { 829 found_fwd = options.remote_forwards + i; 830 break; 831 } 832 } 833 break; 834 } 835 836 if (found_fwd == NULL) 837 error_reason = "port not forwarded"; 838 else if (ftype == MUX_FWD_REMOTE) { 839 /* 840 * This shouldn't fail unless we confused the host/port 841 * between options.remote_forwards and permitted_opens. 842 * However, for dynamic allocated listen ports we need 843 * to lookup the actual listen port. 844 */ 845 listen_port = (fwd.listen_port == 0) ? 846 found_fwd->allocated_port : fwd.listen_port; 847 if (channel_request_rforward_cancel(fwd.listen_host, 848 listen_port) == -1) 849 error_reason = "port not in permitted opens"; 850 } else { /* local and dynamic forwards */ 851 /* Ditto */ 852 if (channel_cancel_lport_listener(fwd.listen_host, 853 fwd.listen_port, fwd.connect_port, 854 options.gateway_ports) == -1) 855 error_reason = "port not found"; 856 } 857 858 if (error_reason == NULL) { 859 buffer_put_int(r, MUX_S_OK); 860 buffer_put_int(r, rid); 861 862 free(found_fwd->listen_host); 863 free(found_fwd->connect_host); 864 found_fwd->listen_host = found_fwd->connect_host = NULL; 865 found_fwd->listen_port = found_fwd->connect_port = 0; 866 } else { 867 buffer_put_int(r, MUX_S_FAILURE); 868 buffer_put_int(r, rid); 869 buffer_put_cstring(r, error_reason); 870 } 871 out: 872 free(fwd_desc); 873 free(fwd.listen_host); 874 free(fwd.connect_host); 875 876 return ret; 877} 878 879static int 880process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 881{ 882 Channel *nc; 883 char *reserved, *chost; 884 u_int cport, i, j; 885 int new_fd[2]; 886 887 chost = reserved = NULL; 888 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 889 (chost = buffer_get_string_ret(m, NULL)) == NULL || 890 buffer_get_int_ret(&cport, m) != 0) { 891 free(reserved); 892 free(chost); 893 error("%s: malformed message", __func__); 894 return -1; 895 } 896 free(reserved); 897 898 debug2("%s: channel %d: request stdio fwd to %s:%u", 899 __func__, c->self, chost, cport); 900 901 /* Gather fds from client */ 902 for(i = 0; i < 2; i++) { 903 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 904 error("%s: failed to receive fd %d from slave", 905 __func__, i); 906 for (j = 0; j < i; j++) 907 close(new_fd[j]); 908 free(chost); 909 910 /* prepare reply */ 911 buffer_put_int(r, MUX_S_FAILURE); 912 buffer_put_int(r, rid); 913 buffer_put_cstring(r, 914 "did not receive file descriptors"); 915 return -1; 916 } 917 } 918 919 debug3("%s: got fds stdin %d, stdout %d", __func__, 920 new_fd[0], new_fd[1]); 921 922 /* XXX support multiple child sessions in future */ 923 if (c->remote_id != -1) { 924 debug2("%s: session already open", __func__); 925 /* prepare reply */ 926 buffer_put_int(r, MUX_S_FAILURE); 927 buffer_put_int(r, rid); 928 buffer_put_cstring(r, "Multiple sessions not supported"); 929 cleanup: 930 close(new_fd[0]); 931 close(new_fd[1]); 932 free(chost); 933 return 0; 934 } 935 936 if (options.control_master == SSHCTL_MASTER_ASK || 937 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 938 if (!ask_permission("Allow forward to %s:%u? ", 939 chost, cport)) { 940 debug2("%s: stdio fwd refused by user", __func__); 941 /* prepare reply */ 942 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 943 buffer_put_int(r, rid); 944 buffer_put_cstring(r, "Permission denied"); 945 goto cleanup; 946 } 947 } 948 949 /* enable nonblocking unless tty */ 950 if (!isatty(new_fd[0])) 951 set_nonblock(new_fd[0]); 952 if (!isatty(new_fd[1])) 953 set_nonblock(new_fd[1]); 954 955 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 956 957 nc->ctl_chan = c->self; /* link session -> control channel */ 958 c->remote_id = nc->self; /* link control -> session channel */ 959 960 debug2("%s: channel_new: %d linked to control channel %d", 961 __func__, nc->self, nc->ctl_chan); 962 963 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 964 965 /* prepare reply */ 966 /* XXX defer until channel confirmed */ 967 buffer_put_int(r, MUX_S_SESSION_OPENED); 968 buffer_put_int(r, rid); 969 buffer_put_int(r, nc->self); 970 971 return 0; 972} 973 974static int 975process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 976{ 977 debug("%s: channel %d: stop listening", __func__, c->self); 978 979 if (options.control_master == SSHCTL_MASTER_ASK || 980 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 981 if (!ask_permission("Disable further multiplexing on shared " 982 "connection to %s? ", host)) { 983 debug2("%s: stop listen refused by user", __func__); 984 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 985 buffer_put_int(r, rid); 986 buffer_put_cstring(r, "Permission denied"); 987 return 0; 988 } 989 } 990 991 if (mux_listener_channel != NULL) { 992 channel_free(mux_listener_channel); 993 client_stop_mux(); 994 free(options.control_path); 995 options.control_path = NULL; 996 mux_listener_channel = NULL; 997 muxserver_sock = -1; 998 } 999 1000 /* prepare reply */ 1001 buffer_put_int(r, MUX_S_OK); 1002 buffer_put_int(r, rid); 1003 1004 return 0; 1005} 1006 1007/* Channel callbacks fired on read/write from mux slave fd */ 1008static int 1009mux_master_read_cb(Channel *c) 1010{ 1011 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1012 Buffer in, out; 1013 void *ptr; 1014 u_int type, rid, have, i; 1015 int ret = -1; 1016 1017 /* Setup ctx and */ 1018 if (c->mux_ctx == NULL) { 1019 state = xcalloc(1, sizeof(*state)); 1020 c->mux_ctx = state; 1021 channel_register_cleanup(c->self, 1022 mux_master_control_cleanup_cb, 0); 1023 1024 /* Send hello */ 1025 buffer_init(&out); 1026 buffer_put_int(&out, MUX_MSG_HELLO); 1027 buffer_put_int(&out, SSHMUX_VER); 1028 /* no extensions */ 1029 buffer_put_string(&c->output, buffer_ptr(&out), 1030 buffer_len(&out)); 1031 buffer_free(&out); 1032 debug3("%s: channel %d: hello sent", __func__, c->self); 1033 return 0; 1034 } 1035 1036 buffer_init(&in); 1037 buffer_init(&out); 1038 1039 /* Channel code ensures that we receive whole packets */ 1040 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1041 malf: 1042 error("%s: malformed message", __func__); 1043 goto out; 1044 } 1045 buffer_append(&in, ptr, have); 1046 1047 if (buffer_get_int_ret(&type, &in) != 0) 1048 goto malf; 1049 debug3("%s: channel %d packet type 0x%08x len %u", 1050 __func__, c->self, type, buffer_len(&in)); 1051 1052 if (type == MUX_MSG_HELLO) 1053 rid = 0; 1054 else { 1055 if (!state->hello_rcvd) { 1056 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1057 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1058 goto out; 1059 } 1060 if (buffer_get_int_ret(&rid, &in) != 0) 1061 goto malf; 1062 } 1063 1064 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1065 if (type == mux_master_handlers[i].type) { 1066 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1067 break; 1068 } 1069 } 1070 if (mux_master_handlers[i].handler == NULL) { 1071 error("%s: unsupported mux message 0x%08x", __func__, type); 1072 buffer_put_int(&out, MUX_S_FAILURE); 1073 buffer_put_int(&out, rid); 1074 buffer_put_cstring(&out, "unsupported request"); 1075 ret = 0; 1076 } 1077 /* Enqueue reply packet */ 1078 if (buffer_len(&out) != 0) { 1079 buffer_put_string(&c->output, buffer_ptr(&out), 1080 buffer_len(&out)); 1081 } 1082 out: 1083 buffer_free(&in); 1084 buffer_free(&out); 1085 return ret; 1086} 1087 1088void 1089mux_exit_message(Channel *c, int exitval) 1090{ 1091 Buffer m; 1092 Channel *mux_chan; 1093 1094 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1095 exitval); 1096 1097 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1098 fatal("%s: channel %d missing mux channel %d", 1099 __func__, c->self, c->ctl_chan); 1100 1101 /* Append exit message packet to control socket output queue */ 1102 buffer_init(&m); 1103 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1104 buffer_put_int(&m, c->self); 1105 buffer_put_int(&m, exitval); 1106 1107 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1108 buffer_free(&m); 1109} 1110 1111void 1112mux_tty_alloc_failed(Channel *c) 1113{ 1114 Buffer m; 1115 Channel *mux_chan; 1116 1117 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1118 1119 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1120 fatal("%s: channel %d missing mux channel %d", 1121 __func__, c->self, c->ctl_chan); 1122 1123 /* Append exit message packet to control socket output queue */ 1124 buffer_init(&m); 1125 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1126 buffer_put_int(&m, c->self); 1127 1128 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1129 buffer_free(&m); 1130} 1131 1132/* Prepare a mux master to listen on a Unix domain socket. */ 1133void 1134muxserver_listen(void) 1135{ 1136 struct sockaddr_un addr; 1137 socklen_t sun_len; 1138 mode_t old_umask; 1139 char *orig_control_path = options.control_path; 1140 char rbuf[16+1]; 1141 u_int i, r; 1142 1143 if (options.control_path == NULL || 1144 options.control_master == SSHCTL_MASTER_NO) 1145 return; 1146 1147 debug("setting up multiplex master socket"); 1148 1149 /* 1150 * Use a temporary path before listen so we can pseudo-atomically 1151 * establish the listening socket in its final location to avoid 1152 * other processes racing in between bind() and listen() and hitting 1153 * an unready socket. 1154 */ 1155 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1156 r = arc4random_uniform(26+26+10); 1157 rbuf[i] = (r < 26) ? 'a' + r : 1158 (r < 26*2) ? 'A' + r - 26 : 1159 '0' + r - 26 - 26; 1160 } 1161 rbuf[sizeof(rbuf) - 1] = '\0'; 1162 options.control_path = NULL; 1163 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1164 debug3("%s: temporary control path %s", __func__, options.control_path); 1165 1166 memset(&addr, '\0', sizeof(addr)); 1167 addr.sun_family = AF_UNIX; 1168 sun_len = offsetof(struct sockaddr_un, sun_path) + 1169 strlen(options.control_path) + 1; 1170 1171 if (strlcpy(addr.sun_path, options.control_path, 1172 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) { 1173 error("ControlPath \"%s\" too long for Unix domain socket", 1174 options.control_path); 1175 goto disable_mux_master; 1176 } 1177 1178 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1179 fatal("%s socket(): %s", __func__, strerror(errno)); 1180 1181 old_umask = umask(0177); 1182 if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) { 1183 if (errno == EINVAL || errno == EADDRINUSE) { 1184 error("ControlSocket %s already exists, " 1185 "disabling multiplexing", options.control_path); 1186 disable_mux_master: 1187 if (muxserver_sock != -1) { 1188 close(muxserver_sock); 1189 muxserver_sock = -1; 1190 } 1191 free(orig_control_path); 1192 free(options.control_path); 1193 options.control_path = NULL; 1194 options.control_master = SSHCTL_MASTER_NO; 1195 return; 1196 } else 1197 fatal("%s bind(): %s", __func__, strerror(errno)); 1198 } 1199 umask(old_umask); 1200 1201 if (listen(muxserver_sock, 64) == -1) 1202 fatal("%s listen(): %s", __func__, strerror(errno)); 1203 1204 /* Now atomically "move" the mux socket into position */ 1205 if (link(options.control_path, orig_control_path) != 0) { 1206 if (errno != EEXIST) { 1207 fatal("%s: link mux listener %s => %s: %s", __func__, 1208 options.control_path, orig_control_path, 1209 strerror(errno)); 1210 } 1211 error("ControlSocket %s already exists, disabling multiplexing", 1212 orig_control_path); 1213 unlink(options.control_path); 1214 goto disable_mux_master; 1215 } 1216 unlink(options.control_path); 1217 free(options.control_path); 1218 options.control_path = orig_control_path; 1219 1220 set_nonblock(muxserver_sock); 1221 1222 mux_listener_channel = channel_new("mux listener", 1223 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1224 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1225 0, options.control_path, 1); 1226 mux_listener_channel->mux_rcb = mux_master_read_cb; 1227 debug3("%s: mux listener channel %d fd %d", __func__, 1228 mux_listener_channel->self, mux_listener_channel->sock); 1229} 1230 1231/* Callback on open confirmation in mux master for a mux client session. */ 1232static void 1233mux_session_confirm(int id, int success, void *arg) 1234{ 1235 struct mux_session_confirm_ctx *cctx = arg; 1236 const char *display; 1237 Channel *c, *cc; 1238 int i; 1239 Buffer reply; 1240 1241 if (cctx == NULL) 1242 fatal("%s: cctx == NULL", __func__); 1243 if ((c = channel_by_id(id)) == NULL) 1244 fatal("%s: no channel for id %d", __func__, id); 1245 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1246 fatal("%s: channel %d lacks control channel %d", __func__, 1247 id, c->ctl_chan); 1248 1249 if (!success) { 1250 debug3("%s: sending failure reply", __func__); 1251 /* prepare reply */ 1252 buffer_init(&reply); 1253 buffer_put_int(&reply, MUX_S_FAILURE); 1254 buffer_put_int(&reply, cctx->rid); 1255 buffer_put_cstring(&reply, "Session open refused by peer"); 1256 goto done; 1257 } 1258 1259 display = getenv("DISPLAY"); 1260 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1261 char *proto, *data; 1262 1263 /* Get reasonable local authentication information. */ 1264 client_x11_get_proto(display, options.xauth_location, 1265 options.forward_x11_trusted, options.forward_x11_timeout, 1266 &proto, &data); 1267 /* Request forwarding with authentication spoofing. */ 1268 debug("Requesting X11 forwarding with authentication " 1269 "spoofing."); 1270 x11_request_forwarding_with_spoofing(id, display, proto, 1271 data, 1); 1272 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1273 /* XXX exit_on_forward_failure */ 1274 } 1275 1276 if (cctx->want_agent_fwd && options.forward_agent) { 1277 debug("Requesting authentication agent forwarding."); 1278 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1279 packet_send(); 1280 } 1281 1282 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1283 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1284 1285 debug3("%s: sending success reply", __func__); 1286 /* prepare reply */ 1287 buffer_init(&reply); 1288 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1289 buffer_put_int(&reply, cctx->rid); 1290 buffer_put_int(&reply, c->self); 1291 1292 done: 1293 /* Send reply */ 1294 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1295 buffer_free(&reply); 1296 1297 if (cc->mux_pause <= 0) 1298 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1299 cc->mux_pause = 0; /* start processing messages again */ 1300 c->open_confirm_ctx = NULL; 1301 buffer_free(&cctx->cmd); 1302 free(cctx->term); 1303 if (cctx->env != NULL) { 1304 for (i = 0; cctx->env[i] != NULL; i++) 1305 free(cctx->env[i]); 1306 free(cctx->env); 1307 } 1308 free(cctx); 1309} 1310 1311/* ** Multiplexing client support */ 1312 1313/* Exit signal handler */ 1314static void 1315control_client_sighandler(int signo) 1316{ 1317 muxclient_terminate = signo; 1318} 1319 1320/* 1321 * Relay signal handler - used to pass some signals from mux client to 1322 * mux master. 1323 */ 1324static void 1325control_client_sigrelay(int signo) 1326{ 1327 int save_errno = errno; 1328 1329 if (muxserver_pid > 1) 1330 kill(muxserver_pid, signo); 1331 1332 errno = save_errno; 1333} 1334 1335static int 1336mux_client_read(int fd, Buffer *b, u_int need) 1337{ 1338 u_int have; 1339 ssize_t len; 1340 u_char *p; 1341 struct pollfd pfd; 1342 1343 pfd.fd = fd; 1344 pfd.events = POLLIN; 1345 p = buffer_append_space(b, need); 1346 for (have = 0; have < need; ) { 1347 if (muxclient_terminate) { 1348 errno = EINTR; 1349 return -1; 1350 } 1351 len = read(fd, p + have, need - have); 1352 if (len < 0) { 1353 switch (errno) { 1354#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1355 case EWOULDBLOCK: 1356#endif 1357 case EAGAIN: 1358 (void)poll(&pfd, 1, -1); 1359 /* FALLTHROUGH */ 1360 case EINTR: 1361 continue; 1362 default: 1363 return -1; 1364 } 1365 } 1366 if (len == 0) { 1367 errno = EPIPE; 1368 return -1; 1369 } 1370 have += (u_int)len; 1371 } 1372 return 0; 1373} 1374 1375static int 1376mux_client_write_packet(int fd, Buffer *m) 1377{ 1378 Buffer queue; 1379 u_int have, need; 1380 int oerrno, len; 1381 u_char *ptr; 1382 struct pollfd pfd; 1383 1384 pfd.fd = fd; 1385 pfd.events = POLLOUT; 1386 buffer_init(&queue); 1387 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1388 1389 need = buffer_len(&queue); 1390 ptr = buffer_ptr(&queue); 1391 1392 for (have = 0; have < need; ) { 1393 if (muxclient_terminate) { 1394 buffer_free(&queue); 1395 errno = EINTR; 1396 return -1; 1397 } 1398 len = write(fd, ptr + have, need - have); 1399 if (len < 0) { 1400 switch (errno) { 1401#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1402 case EWOULDBLOCK: 1403#endif 1404 case EAGAIN: 1405 (void)poll(&pfd, 1, -1); 1406 /* FALLTHROUGH */ 1407 case EINTR: 1408 continue; 1409 default: 1410 oerrno = errno; 1411 buffer_free(&queue); 1412 errno = oerrno; 1413 return -1; 1414 } 1415 } 1416 if (len == 0) { 1417 buffer_free(&queue); 1418 errno = EPIPE; 1419 return -1; 1420 } 1421 have += (u_int)len; 1422 } 1423 buffer_free(&queue); 1424 return 0; 1425} 1426 1427static int 1428mux_client_read_packet(int fd, Buffer *m) 1429{ 1430 Buffer queue; 1431 u_int need, have; 1432 void *ptr; 1433 int oerrno; 1434 1435 buffer_init(&queue); 1436 if (mux_client_read(fd, &queue, 4) != 0) { 1437 if ((oerrno = errno) == EPIPE) 1438 debug3("%s: read header failed: %s", __func__, 1439 strerror(errno)); 1440 buffer_free(&queue); 1441 errno = oerrno; 1442 return -1; 1443 } 1444 need = get_u32(buffer_ptr(&queue)); 1445 if (mux_client_read(fd, &queue, need) != 0) { 1446 oerrno = errno; 1447 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1448 buffer_free(&queue); 1449 errno = oerrno; 1450 return -1; 1451 } 1452 ptr = buffer_get_string_ptr(&queue, &have); 1453 buffer_append(m, ptr, have); 1454 buffer_free(&queue); 1455 return 0; 1456} 1457 1458static int 1459mux_client_hello_exchange(int fd) 1460{ 1461 Buffer m; 1462 u_int type, ver; 1463 1464 buffer_init(&m); 1465 buffer_put_int(&m, MUX_MSG_HELLO); 1466 buffer_put_int(&m, SSHMUX_VER); 1467 /* no extensions */ 1468 1469 if (mux_client_write_packet(fd, &m) != 0) 1470 fatal("%s: write packet: %s", __func__, strerror(errno)); 1471 1472 buffer_clear(&m); 1473 1474 /* Read their HELLO */ 1475 if (mux_client_read_packet(fd, &m) != 0) { 1476 buffer_free(&m); 1477 return -1; 1478 } 1479 1480 type = buffer_get_int(&m); 1481 if (type != MUX_MSG_HELLO) 1482 fatal("%s: expected HELLO (%u) received %u", 1483 __func__, MUX_MSG_HELLO, type); 1484 ver = buffer_get_int(&m); 1485 if (ver != SSHMUX_VER) 1486 fatal("Unsupported multiplexing protocol version %d " 1487 "(expected %d)", ver, SSHMUX_VER); 1488 debug2("%s: master version %u", __func__, ver); 1489 /* No extensions are presently defined */ 1490 while (buffer_len(&m) > 0) { 1491 char *name = buffer_get_string(&m, NULL); 1492 char *value = buffer_get_string(&m, NULL); 1493 1494 debug2("Unrecognised master extension \"%s\"", name); 1495 free(name); 1496 free(value); 1497 } 1498 buffer_free(&m); 1499 return 0; 1500} 1501 1502static u_int 1503mux_client_request_alive(int fd) 1504{ 1505 Buffer m; 1506 char *e; 1507 u_int pid, type, rid; 1508 1509 debug3("%s: entering", __func__); 1510 1511 buffer_init(&m); 1512 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1513 buffer_put_int(&m, muxclient_request_id); 1514 1515 if (mux_client_write_packet(fd, &m) != 0) 1516 fatal("%s: write packet: %s", __func__, strerror(errno)); 1517 1518 buffer_clear(&m); 1519 1520 /* Read their reply */ 1521 if (mux_client_read_packet(fd, &m) != 0) { 1522 buffer_free(&m); 1523 return 0; 1524 } 1525 1526 type = buffer_get_int(&m); 1527 if (type != MUX_S_ALIVE) { 1528 e = buffer_get_string(&m, NULL); 1529 fatal("%s: master returned error: %s", __func__, e); 1530 } 1531 1532 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1533 fatal("%s: out of sequence reply: my id %u theirs %u", 1534 __func__, muxclient_request_id, rid); 1535 pid = buffer_get_int(&m); 1536 buffer_free(&m); 1537 1538 debug3("%s: done pid = %u", __func__, pid); 1539 1540 muxclient_request_id++; 1541 1542 return pid; 1543} 1544 1545static void 1546mux_client_request_terminate(int fd) 1547{ 1548 Buffer m; 1549 char *e; 1550 u_int type, rid; 1551 1552 debug3("%s: entering", __func__); 1553 1554 buffer_init(&m); 1555 buffer_put_int(&m, MUX_C_TERMINATE); 1556 buffer_put_int(&m, muxclient_request_id); 1557 1558 if (mux_client_write_packet(fd, &m) != 0) 1559 fatal("%s: write packet: %s", __func__, strerror(errno)); 1560 1561 buffer_clear(&m); 1562 1563 /* Read their reply */ 1564 if (mux_client_read_packet(fd, &m) != 0) { 1565 /* Remote end exited already */ 1566 if (errno == EPIPE) { 1567 buffer_free(&m); 1568 return; 1569 } 1570 fatal("%s: read from master failed: %s", 1571 __func__, strerror(errno)); 1572 } 1573 1574 type = buffer_get_int(&m); 1575 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1576 fatal("%s: out of sequence reply: my id %u theirs %u", 1577 __func__, muxclient_request_id, rid); 1578 switch (type) { 1579 case MUX_S_OK: 1580 break; 1581 case MUX_S_PERMISSION_DENIED: 1582 e = buffer_get_string(&m, NULL); 1583 fatal("Master refused termination request: %s", e); 1584 case MUX_S_FAILURE: 1585 e = buffer_get_string(&m, NULL); 1586 fatal("%s: termination request failed: %s", __func__, e); 1587 default: 1588 fatal("%s: unexpected response from master 0x%08x", 1589 __func__, type); 1590 } 1591 buffer_free(&m); 1592 muxclient_request_id++; 1593} 1594 1595static int 1596mux_client_forward(int fd, int cancel_flag, u_int ftype, Forward *fwd) 1597{ 1598 Buffer m; 1599 char *e, *fwd_desc; 1600 u_int type, rid; 1601 1602 fwd_desc = format_forward(ftype, fwd); 1603 debug("Requesting %s %s", 1604 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1605 free(fwd_desc); 1606 1607 buffer_init(&m); 1608 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1609 buffer_put_int(&m, muxclient_request_id); 1610 buffer_put_int(&m, ftype); 1611 buffer_put_cstring(&m, 1612 fwd->listen_host == NULL ? "" : fwd->listen_host); 1613 buffer_put_int(&m, fwd->listen_port); 1614 buffer_put_cstring(&m, 1615 fwd->connect_host == NULL ? "" : fwd->connect_host); 1616 buffer_put_int(&m, fwd->connect_port); 1617 1618 if (mux_client_write_packet(fd, &m) != 0) 1619 fatal("%s: write packet: %s", __func__, strerror(errno)); 1620 1621 buffer_clear(&m); 1622 1623 /* Read their reply */ 1624 if (mux_client_read_packet(fd, &m) != 0) { 1625 buffer_free(&m); 1626 return -1; 1627 } 1628 1629 type = buffer_get_int(&m); 1630 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1631 fatal("%s: out of sequence reply: my id %u theirs %u", 1632 __func__, muxclient_request_id, rid); 1633 switch (type) { 1634 case MUX_S_OK: 1635 break; 1636 case MUX_S_REMOTE_PORT: 1637 if (cancel_flag) 1638 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1639 fwd->allocated_port = buffer_get_int(&m); 1640 logit("Allocated port %u for remote forward to %s:%d", 1641 fwd->allocated_port, 1642 fwd->connect_host ? fwd->connect_host : "", 1643 fwd->connect_port); 1644 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1645 fprintf(stdout, "%u\n", fwd->allocated_port); 1646 break; 1647 case MUX_S_PERMISSION_DENIED: 1648 e = buffer_get_string(&m, NULL); 1649 buffer_free(&m); 1650 error("Master refused forwarding request: %s", e); 1651 return -1; 1652 case MUX_S_FAILURE: 1653 e = buffer_get_string(&m, NULL); 1654 buffer_free(&m); 1655 error("%s: forwarding request failed: %s", __func__, e); 1656 return -1; 1657 default: 1658 fatal("%s: unexpected response from master 0x%08x", 1659 __func__, type); 1660 } 1661 buffer_free(&m); 1662 1663 muxclient_request_id++; 1664 return 0; 1665} 1666 1667static int 1668mux_client_forwards(int fd, int cancel_flag) 1669{ 1670 int i, ret = 0; 1671 1672 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1673 cancel_flag ? "cancel" : "request", 1674 options.num_local_forwards, options.num_remote_forwards); 1675 1676 /* XXX ExitOnForwardingFailure */ 1677 for (i = 0; i < options.num_local_forwards; i++) { 1678 if (mux_client_forward(fd, cancel_flag, 1679 options.local_forwards[i].connect_port == 0 ? 1680 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1681 options.local_forwards + i) != 0) 1682 ret = -1; 1683 } 1684 for (i = 0; i < options.num_remote_forwards; i++) { 1685 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1686 options.remote_forwards + i) != 0) 1687 ret = -1; 1688 } 1689 return ret; 1690} 1691 1692static int 1693mux_client_request_session(int fd) 1694{ 1695 Buffer m; 1696 char *e, *term; 1697 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1698 extern char **environ; 1699 int devnull, rawmode; 1700 1701 debug3("%s: entering", __func__); 1702 1703 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1704 error("%s: master alive request failed", __func__); 1705 return -1; 1706 } 1707 1708 signal(SIGPIPE, SIG_IGN); 1709 1710 if (stdin_null_flag) { 1711 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1712 fatal("open(/dev/null): %s", strerror(errno)); 1713 if (dup2(devnull, STDIN_FILENO) == -1) 1714 fatal("dup2: %s", strerror(errno)); 1715 if (devnull > STDERR_FILENO) 1716 close(devnull); 1717 } 1718 1719 term = getenv("TERM"); 1720 1721 buffer_init(&m); 1722 buffer_put_int(&m, MUX_C_NEW_SESSION); 1723 buffer_put_int(&m, muxclient_request_id); 1724 buffer_put_cstring(&m, ""); /* reserved */ 1725 buffer_put_int(&m, tty_flag); 1726 buffer_put_int(&m, options.forward_x11); 1727 buffer_put_int(&m, options.forward_agent); 1728 buffer_put_int(&m, subsystem_flag); 1729 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1730 0xffffffff : (u_int)options.escape_char); 1731 buffer_put_cstring(&m, term == NULL ? "" : term); 1732 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1733 1734 if (options.num_send_env > 0 && environ != NULL) { 1735 /* Pass environment */ 1736 for (i = 0; environ[i] != NULL; i++) { 1737 if (env_permitted(environ[i])) { 1738 buffer_put_cstring(&m, environ[i]); 1739 } 1740 } 1741 } 1742 1743 if (mux_client_write_packet(fd, &m) != 0) 1744 fatal("%s: write packet: %s", __func__, strerror(errno)); 1745 1746 /* Send the stdio file descriptors */ 1747 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1748 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1749 mm_send_fd(fd, STDERR_FILENO) == -1) 1750 fatal("%s: send fds failed", __func__); 1751 1752 debug3("%s: session request sent", __func__); 1753 1754 /* Read their reply */ 1755 buffer_clear(&m); 1756 if (mux_client_read_packet(fd, &m) != 0) { 1757 error("%s: read from master failed: %s", 1758 __func__, strerror(errno)); 1759 buffer_free(&m); 1760 return -1; 1761 } 1762 1763 type = buffer_get_int(&m); 1764 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1765 fatal("%s: out of sequence reply: my id %u theirs %u", 1766 __func__, muxclient_request_id, rid); 1767 switch (type) { 1768 case MUX_S_SESSION_OPENED: 1769 sid = buffer_get_int(&m); 1770 debug("%s: master session id: %u", __func__, sid); 1771 break; 1772 case MUX_S_PERMISSION_DENIED: 1773 e = buffer_get_string(&m, NULL); 1774 buffer_free(&m); 1775 error("Master refused session request: %s", e); 1776 return -1; 1777 case MUX_S_FAILURE: 1778 e = buffer_get_string(&m, NULL); 1779 buffer_free(&m); 1780 error("%s: session request failed: %s", __func__, e); 1781 return -1; 1782 default: 1783 buffer_free(&m); 1784 error("%s: unexpected response from master 0x%08x", 1785 __func__, type); 1786 return -1; 1787 } 1788 muxclient_request_id++; 1789 1790 signal(SIGHUP, control_client_sighandler); 1791 signal(SIGINT, control_client_sighandler); 1792 signal(SIGTERM, control_client_sighandler); 1793 signal(SIGWINCH, control_client_sigrelay); 1794 1795 rawmode = tty_flag; 1796 if (tty_flag) 1797 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1798 1799 /* 1800 * Stick around until the controlee closes the client_fd. 1801 * Before it does, it is expected to write an exit message. 1802 * This process must read the value and wait for the closure of 1803 * the client_fd; if this one closes early, the multiplex master will 1804 * terminate early too (possibly losing data). 1805 */ 1806 for (exitval = 255, exitval_seen = 0;;) { 1807 buffer_clear(&m); 1808 if (mux_client_read_packet(fd, &m) != 0) 1809 break; 1810 type = buffer_get_int(&m); 1811 switch (type) { 1812 case MUX_S_TTY_ALLOC_FAIL: 1813 if ((esid = buffer_get_int(&m)) != sid) 1814 fatal("%s: tty alloc fail on unknown session: " 1815 "my id %u theirs %u", 1816 __func__, sid, esid); 1817 leave_raw_mode(options.request_tty == 1818 REQUEST_TTY_FORCE); 1819 rawmode = 0; 1820 continue; 1821 case MUX_S_EXIT_MESSAGE: 1822 if ((esid = buffer_get_int(&m)) != sid) 1823 fatal("%s: exit on unknown session: " 1824 "my id %u theirs %u", 1825 __func__, sid, esid); 1826 if (exitval_seen) 1827 fatal("%s: exitval sent twice", __func__); 1828 exitval = buffer_get_int(&m); 1829 exitval_seen = 1; 1830 continue; 1831 default: 1832 e = buffer_get_string(&m, NULL); 1833 fatal("%s: master returned error: %s", __func__, e); 1834 } 1835 } 1836 1837 close(fd); 1838 if (rawmode) 1839 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1840 1841 if (muxclient_terminate) { 1842 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1843 exitval = 255; 1844 } else if (!exitval_seen) { 1845 debug2("Control master terminated unexpectedly"); 1846 exitval = 255; 1847 } else 1848 debug2("Received exit status from master %d", exitval); 1849 1850 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1851 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1852 1853 exit(exitval); 1854} 1855 1856static int 1857mux_client_request_stdio_fwd(int fd) 1858{ 1859 Buffer m; 1860 char *e; 1861 u_int type, rid, sid; 1862 int devnull; 1863 1864 debug3("%s: entering", __func__); 1865 1866 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1867 error("%s: master alive request failed", __func__); 1868 return -1; 1869 } 1870 1871 signal(SIGPIPE, SIG_IGN); 1872 1873 if (stdin_null_flag) { 1874 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1875 fatal("open(/dev/null): %s", strerror(errno)); 1876 if (dup2(devnull, STDIN_FILENO) == -1) 1877 fatal("dup2: %s", strerror(errno)); 1878 if (devnull > STDERR_FILENO) 1879 close(devnull); 1880 } 1881 1882 buffer_init(&m); 1883 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1884 buffer_put_int(&m, muxclient_request_id); 1885 buffer_put_cstring(&m, ""); /* reserved */ 1886 buffer_put_cstring(&m, stdio_forward_host); 1887 buffer_put_int(&m, stdio_forward_port); 1888 1889 if (mux_client_write_packet(fd, &m) != 0) 1890 fatal("%s: write packet: %s", __func__, strerror(errno)); 1891 1892 /* Send the stdio file descriptors */ 1893 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1894 mm_send_fd(fd, STDOUT_FILENO) == -1) 1895 fatal("%s: send fds failed", __func__); 1896 1897 debug3("%s: stdio forward request sent", __func__); 1898 1899 /* Read their reply */ 1900 buffer_clear(&m); 1901 1902 if (mux_client_read_packet(fd, &m) != 0) { 1903 error("%s: read from master failed: %s", 1904 __func__, strerror(errno)); 1905 buffer_free(&m); 1906 return -1; 1907 } 1908 1909 type = buffer_get_int(&m); 1910 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1911 fatal("%s: out of sequence reply: my id %u theirs %u", 1912 __func__, muxclient_request_id, rid); 1913 switch (type) { 1914 case MUX_S_SESSION_OPENED: 1915 sid = buffer_get_int(&m); 1916 debug("%s: master session id: %u", __func__, sid); 1917 break; 1918 case MUX_S_PERMISSION_DENIED: 1919 e = buffer_get_string(&m, NULL); 1920 buffer_free(&m); 1921 fatal("Master refused stdio forwarding request: %s", e); 1922 case MUX_S_FAILURE: 1923 e = buffer_get_string(&m, NULL); 1924 buffer_free(&m); 1925 fatal("%s: stdio forwarding request failed: %s", __func__, e); 1926 default: 1927 buffer_free(&m); 1928 error("%s: unexpected response from master 0x%08x", 1929 __func__, type); 1930 return -1; 1931 } 1932 muxclient_request_id++; 1933 1934 signal(SIGHUP, control_client_sighandler); 1935 signal(SIGINT, control_client_sighandler); 1936 signal(SIGTERM, control_client_sighandler); 1937 signal(SIGWINCH, control_client_sigrelay); 1938 1939 /* 1940 * Stick around until the controlee closes the client_fd. 1941 */ 1942 buffer_clear(&m); 1943 if (mux_client_read_packet(fd, &m) != 0) { 1944 if (errno == EPIPE || 1945 (errno == EINTR && muxclient_terminate != 0)) 1946 return 0; 1947 fatal("%s: mux_client_read_packet: %s", 1948 __func__, strerror(errno)); 1949 } 1950 fatal("%s: master returned unexpected message %u", __func__, type); 1951} 1952 1953static void 1954mux_client_request_stop_listening(int fd) 1955{ 1956 Buffer m; 1957 char *e; 1958 u_int type, rid; 1959 1960 debug3("%s: entering", __func__); 1961 1962 buffer_init(&m); 1963 buffer_put_int(&m, MUX_C_STOP_LISTENING); 1964 buffer_put_int(&m, muxclient_request_id); 1965 1966 if (mux_client_write_packet(fd, &m) != 0) 1967 fatal("%s: write packet: %s", __func__, strerror(errno)); 1968 1969 buffer_clear(&m); 1970 1971 /* Read their reply */ 1972 if (mux_client_read_packet(fd, &m) != 0) 1973 fatal("%s: read from master failed: %s", 1974 __func__, strerror(errno)); 1975 1976 type = buffer_get_int(&m); 1977 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1978 fatal("%s: out of sequence reply: my id %u theirs %u", 1979 __func__, muxclient_request_id, rid); 1980 switch (type) { 1981 case MUX_S_OK: 1982 break; 1983 case MUX_S_PERMISSION_DENIED: 1984 e = buffer_get_string(&m, NULL); 1985 fatal("Master refused stop listening request: %s", e); 1986 case MUX_S_FAILURE: 1987 e = buffer_get_string(&m, NULL); 1988 fatal("%s: stop listening request failed: %s", __func__, e); 1989 default: 1990 fatal("%s: unexpected response from master 0x%08x", 1991 __func__, type); 1992 } 1993 buffer_free(&m); 1994 muxclient_request_id++; 1995} 1996 1997/* Multiplex client main loop. */ 1998void 1999muxclient(const char *path) 2000{ 2001 struct sockaddr_un addr; 2002 socklen_t sun_len; 2003 int sock; 2004 u_int pid; 2005 2006 if (muxclient_command == 0) { 2007 if (stdio_forward_host != NULL) 2008 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2009 else 2010 muxclient_command = SSHMUX_COMMAND_OPEN; 2011 } 2012 2013 switch (options.control_master) { 2014 case SSHCTL_MASTER_AUTO: 2015 case SSHCTL_MASTER_AUTO_ASK: 2016 debug("auto-mux: Trying existing master"); 2017 /* FALLTHROUGH */ 2018 case SSHCTL_MASTER_NO: 2019 break; 2020 default: 2021 return; 2022 } 2023 2024 memset(&addr, '\0', sizeof(addr)); 2025 addr.sun_family = AF_UNIX; 2026 sun_len = offsetof(struct sockaddr_un, sun_path) + 2027 strlen(path) + 1; 2028 2029 if (strlcpy(addr.sun_path, path, 2030 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2031 fatal("ControlPath too long"); 2032 2033 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2034 fatal("%s socket(): %s", __func__, strerror(errno)); 2035 2036 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2037 switch (muxclient_command) { 2038 case SSHMUX_COMMAND_OPEN: 2039 case SSHMUX_COMMAND_STDIO_FWD: 2040 break; 2041 default: 2042 fatal("Control socket connect(%.100s): %s", path, 2043 strerror(errno)); 2044 } 2045 if (errno == ECONNREFUSED && 2046 options.control_master != SSHCTL_MASTER_NO) { 2047 debug("Stale control socket %.100s, unlinking", path); 2048 unlink(path); 2049 } else if (errno == ENOENT) { 2050 debug("Control socket \"%.100s\" does not exist", path); 2051 } else { 2052 error("Control socket connect(%.100s): %s", path, 2053 strerror(errno)); 2054 } 2055 close(sock); 2056 return; 2057 } 2058 set_nonblock(sock); 2059 2060 if (mux_client_hello_exchange(sock) != 0) { 2061 error("%s: master hello exchange failed", __func__); 2062 close(sock); 2063 return; 2064 } 2065 2066 switch (muxclient_command) { 2067 case SSHMUX_COMMAND_ALIVE_CHECK: 2068 if ((pid = mux_client_request_alive(sock)) == 0) 2069 fatal("%s: master alive check failed", __func__); 2070 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2071 exit(0); 2072 case SSHMUX_COMMAND_TERMINATE: 2073 mux_client_request_terminate(sock); 2074 fprintf(stderr, "Exit request sent.\r\n"); 2075 exit(0); 2076 case SSHMUX_COMMAND_FORWARD: 2077 if (mux_client_forwards(sock, 0) != 0) 2078 fatal("%s: master forward request failed", __func__); 2079 exit(0); 2080 case SSHMUX_COMMAND_OPEN: 2081 if (mux_client_forwards(sock, 0) != 0) { 2082 error("%s: master forward request failed", __func__); 2083 return; 2084 } 2085 mux_client_request_session(sock); 2086 return; 2087 case SSHMUX_COMMAND_STDIO_FWD: 2088 mux_client_request_stdio_fwd(sock); 2089 exit(0); 2090 case SSHMUX_COMMAND_STOP: 2091 mux_client_request_stop_listening(sock); 2092 fprintf(stderr, "Stop listening request sent.\r\n"); 2093 exit(0); 2094 case SSHMUX_COMMAND_CANCEL_FWD: 2095 if (mux_client_forwards(sock, 1) != 0) 2096 error("%s: master cancel forward request failed", 2097 __func__); 2098 exit(0); 2099 default: 2100 fatal("unrecognised muxclient_command %d", muxclient_command); 2101 } 2102} 2103