mux.c revision 294666
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__RCSID("$FreeBSD: stable/10/crypto/openssh/mux.c 294666 2016-01-24 15:44:57Z des $"); 35 36#include <sys/types.h> 37#include <sys/param.h> 38#include <sys/stat.h> 39#include <sys/socket.h> 40#include <sys/un.h> 41 42#include <errno.h> 43#include <fcntl.h> 44#include <signal.h> 45#include <stdarg.h> 46#include <stddef.h> 47#include <stdlib.h> 48#include <stdio.h> 49#include <string.h> 50#include <unistd.h> 51#ifdef HAVE_PATHS_H 52#include <paths.h> 53#endif 54 55#ifdef HAVE_POLL_H 56#include <poll.h> 57#else 58# ifdef HAVE_SYS_POLL_H 59# include <sys/poll.h> 60# endif 61#endif 62 63#ifdef HAVE_UTIL_H 64# include <util.h> 65#endif 66 67#include "openbsd-compat/sys-queue.h" 68#include "xmalloc.h" 69#include "log.h" 70#include "ssh.h" 71#include "ssh2.h" 72#include "pathnames.h" 73#include "misc.h" 74#include "match.h" 75#include "buffer.h" 76#include "channels.h" 77#include "msg.h" 78#include "packet.h" 79#include "monitor_fdpass.h" 80#include "sshpty.h" 81#include "key.h" 82#include "readconf.h" 83#include "clientloop.h" 84 85/* from ssh.c */ 86extern int tty_flag; 87extern Options options; 88extern int stdin_null_flag; 89extern char *host; 90extern int subsystem_flag; 91extern Buffer command; 92extern volatile sig_atomic_t quit_pending; 93extern char *stdio_forward_host; 94extern int stdio_forward_port; 95 96/* Context for session open confirmation callback */ 97struct mux_session_confirm_ctx { 98 u_int want_tty; 99 u_int want_subsys; 100 u_int want_x_fwd; 101 u_int want_agent_fwd; 102 Buffer cmd; 103 char *term; 104 struct termios tio; 105 char **env; 106 u_int rid; 107}; 108 109/* Context for global channel callback */ 110struct mux_channel_confirm_ctx { 111 u_int cid; /* channel id */ 112 u_int rid; /* request id */ 113 int fid; /* forward id */ 114}; 115 116/* fd to control socket */ 117int muxserver_sock = -1; 118 119/* client request id */ 120u_int muxclient_request_id = 0; 121 122/* Multiplexing control command */ 123u_int muxclient_command = 0; 124 125/* Set when signalled. */ 126static volatile sig_atomic_t muxclient_terminate = 0; 127 128/* PID of multiplex server */ 129static u_int muxserver_pid = 0; 130 131static Channel *mux_listener_channel = NULL; 132 133struct mux_master_state { 134 int hello_rcvd; 135}; 136 137/* mux protocol messages */ 138#define MUX_MSG_HELLO 0x00000001 139#define MUX_C_NEW_SESSION 0x10000002 140#define MUX_C_ALIVE_CHECK 0x10000004 141#define MUX_C_TERMINATE 0x10000005 142#define MUX_C_OPEN_FWD 0x10000006 143#define MUX_C_CLOSE_FWD 0x10000007 144#define MUX_C_NEW_STDIO_FWD 0x10000008 145#define MUX_C_STOP_LISTENING 0x10000009 146#define MUX_S_OK 0x80000001 147#define MUX_S_PERMISSION_DENIED 0x80000002 148#define MUX_S_FAILURE 0x80000003 149#define MUX_S_EXIT_MESSAGE 0x80000004 150#define MUX_S_ALIVE 0x80000005 151#define MUX_S_SESSION_OPENED 0x80000006 152#define MUX_S_REMOTE_PORT 0x80000007 153#define MUX_S_TTY_ALLOC_FAIL 0x80000008 154 155/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 156#define MUX_FWD_LOCAL 1 157#define MUX_FWD_REMOTE 2 158#define MUX_FWD_DYNAMIC 3 159 160static void mux_session_confirm(int, int, void *); 161 162static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 163static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 164static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 165static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 166static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 167static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 168static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 169static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 170 171static const struct { 172 u_int type; 173 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 174} mux_master_handlers[] = { 175 { MUX_MSG_HELLO, process_mux_master_hello }, 176 { MUX_C_NEW_SESSION, process_mux_new_session }, 177 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 178 { MUX_C_TERMINATE, process_mux_terminate }, 179 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 180 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 181 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 182 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 183 { 0, NULL } 184}; 185 186/* Cleanup callback fired on closure of mux slave _session_ channel */ 187/* ARGSUSED */ 188static void 189mux_master_session_cleanup_cb(int cid, void *unused) 190{ 191 Channel *cc, *c = channel_by_id(cid); 192 193 debug3("%s: entering for channel %d", __func__, cid); 194 if (c == NULL) 195 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 196 if (c->ctl_chan != -1) { 197 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 198 fatal("%s: channel %d missing control channel %d", 199 __func__, c->self, c->ctl_chan); 200 c->ctl_chan = -1; 201 cc->remote_id = -1; 202 chan_rcvd_oclose(cc); 203 } 204 channel_cancel_cleanup(c->self); 205} 206 207/* Cleanup callback fired on closure of mux slave _control_ channel */ 208/* ARGSUSED */ 209static void 210mux_master_control_cleanup_cb(int cid, void *unused) 211{ 212 Channel *sc, *c = channel_by_id(cid); 213 214 debug3("%s: entering for channel %d", __func__, cid); 215 if (c == NULL) 216 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 217 if (c->remote_id != -1) { 218 if ((sc = channel_by_id(c->remote_id)) == NULL) 219 fatal("%s: channel %d missing session channel %d", 220 __func__, c->self, c->remote_id); 221 c->remote_id = -1; 222 sc->ctl_chan = -1; 223 if (sc->type != SSH_CHANNEL_OPEN && 224 sc->type != SSH_CHANNEL_OPENING) { 225 debug2("%s: channel %d: not open", __func__, sc->self); 226 chan_mark_dead(sc); 227 } else { 228 if (sc->istate == CHAN_INPUT_OPEN) 229 chan_read_failed(sc); 230 if (sc->ostate == CHAN_OUTPUT_OPEN) 231 chan_write_failed(sc); 232 } 233 } 234 channel_cancel_cleanup(c->self); 235} 236 237/* Check mux client environment variables before passing them to mux master. */ 238static int 239env_permitted(char *env) 240{ 241 int i, ret; 242 char name[1024], *cp; 243 244 if ((cp = strchr(env, '=')) == NULL || cp == env) 245 return 0; 246 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 247 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 248 error("env_permitted: name '%.100s...' too long", env); 249 return 0; 250 } 251 252 for (i = 0; i < options.num_send_env; i++) 253 if (match_pattern(name, options.send_env[i])) 254 return 1; 255 256 return 0; 257} 258 259/* Mux master protocol message handlers */ 260 261static int 262process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 263{ 264 u_int ver; 265 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 266 267 if (state == NULL) 268 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 269 if (state->hello_rcvd) { 270 error("%s: HELLO received twice", __func__); 271 return -1; 272 } 273 if (buffer_get_int_ret(&ver, m) != 0) { 274 malf: 275 error("%s: malformed message", __func__); 276 return -1; 277 } 278 if (ver != SSHMUX_VER) { 279 error("Unsupported multiplexing protocol version %d " 280 "(expected %d)", ver, SSHMUX_VER); 281 return -1; 282 } 283 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 284 285 /* No extensions are presently defined */ 286 while (buffer_len(m) > 0) { 287 char *name = buffer_get_string_ret(m, NULL); 288 char *value = buffer_get_string_ret(m, NULL); 289 290 if (name == NULL || value == NULL) { 291 free(name); 292 free(value); 293 goto malf; 294 } 295 debug2("Unrecognised slave extension \"%s\"", name); 296 free(name); 297 free(value); 298 } 299 state->hello_rcvd = 1; 300 return 0; 301} 302 303static int 304process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 305{ 306 Channel *nc; 307 struct mux_session_confirm_ctx *cctx; 308 char *reserved, *cmd, *cp; 309 u_int i, j, len, env_len, escape_char, window, packetmax; 310 int new_fd[3]; 311 312 /* Reply for SSHMUX_COMMAND_OPEN */ 313 cctx = xcalloc(1, sizeof(*cctx)); 314 cctx->term = NULL; 315 cctx->rid = rid; 316 cmd = reserved = NULL; 317 cctx->env = NULL; 318 env_len = 0; 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 free(cmd); 329 free(reserved); 330 for (j = 0; j < env_len; j++) 331 free(cctx->env[j]); 332 free(cctx->env); 333 free(cctx->term); 334 free(cctx); 335 error("%s: malformed message", __func__); 336 return -1; 337 } 338 free(reserved); 339 reserved = NULL; 340 341 while (buffer_len(m) > 0) { 342#define MUX_MAX_ENV_VARS 4096 343 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 344 goto malf; 345 if (!env_permitted(cp)) { 346 free(cp); 347 continue; 348 } 349 cctx->env = xrealloc(cctx->env, env_len + 2, 350 sizeof(*cctx->env)); 351 cctx->env[env_len++] = cp; 352 cctx->env[env_len] = NULL; 353 if (env_len > MUX_MAX_ENV_VARS) { 354 error(">%d environment variables received, ignoring " 355 "additional", MUX_MAX_ENV_VARS); 356 break; 357 } 358 } 359 360 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 361 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 362 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 363 cctx->want_subsys, cctx->term, cmd, env_len); 364 365 buffer_init(&cctx->cmd); 366 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 367 free(cmd); 368 cmd = NULL; 369 370 /* Gather fds from client */ 371 for(i = 0; i < 3; i++) { 372 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 373 error("%s: failed to receive fd %d from slave", 374 __func__, i); 375 for (j = 0; j < i; j++) 376 close(new_fd[j]); 377 for (j = 0; j < env_len; j++) 378 free(cctx->env[j]); 379 free(cctx->env); 380 free(cctx->term); 381 buffer_free(&cctx->cmd); 382 free(cctx); 383 384 /* prepare reply */ 385 buffer_put_int(r, MUX_S_FAILURE); 386 buffer_put_int(r, rid); 387 buffer_put_cstring(r, 388 "did not receive file descriptors"); 389 return -1; 390 } 391 } 392 393 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 394 new_fd[0], new_fd[1], new_fd[2]); 395 396 /* XXX support multiple child sessions in future */ 397 if (c->remote_id != -1) { 398 debug2("%s: session already open", __func__); 399 /* prepare reply */ 400 buffer_put_int(r, MUX_S_FAILURE); 401 buffer_put_int(r, rid); 402 buffer_put_cstring(r, "Multiple sessions not supported"); 403 cleanup: 404 close(new_fd[0]); 405 close(new_fd[1]); 406 close(new_fd[2]); 407 free(cctx->term); 408 if (env_len != 0) { 409 for (i = 0; i < env_len; i++) 410 free(cctx->env[i]); 411 free(cctx->env); 412 } 413 buffer_free(&cctx->cmd); 414 free(cctx); 415 return 0; 416 } 417 418 if (options.control_master == SSHCTL_MASTER_ASK || 419 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 420 if (!ask_permission("Allow shared connection to %s? ", host)) { 421 debug2("%s: session refused by user", __func__); 422 /* prepare reply */ 423 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 424 buffer_put_int(r, rid); 425 buffer_put_cstring(r, "Permission denied"); 426 goto cleanup; 427 } 428 } 429 430 /* Try to pick up ttymodes from client before it goes raw */ 431 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 432 error("%s: tcgetattr: %s", __func__, strerror(errno)); 433 434 /* enable nonblocking unless tty */ 435 if (!isatty(new_fd[0])) 436 set_nonblock(new_fd[0]); 437 if (!isatty(new_fd[1])) 438 set_nonblock(new_fd[1]); 439 if (!isatty(new_fd[2])) 440 set_nonblock(new_fd[2]); 441 442 window = CHAN_SES_WINDOW_DEFAULT; 443 packetmax = CHAN_SES_PACKET_DEFAULT; 444 if (cctx->want_tty) { 445 window >>= 1; 446 packetmax >>= 1; 447 } 448 449 nc = channel_new("session", SSH_CHANNEL_OPENING, 450 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 451 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 452 453 nc->ctl_chan = c->self; /* link session -> control channel */ 454 c->remote_id = nc->self; /* link control -> session channel */ 455 456 if (cctx->want_tty && escape_char != 0xffffffff) { 457 channel_register_filter(nc->self, 458 client_simple_escape_filter, NULL, 459 client_filter_cleanup, 460 client_new_escape_filter_ctx((int)escape_char)); 461 } 462 463 debug2("%s: channel_new: %d linked to control channel %d", 464 __func__, nc->self, nc->ctl_chan); 465 466 channel_send_open(nc->self); 467 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 468 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 469 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 470 471 /* reply is deferred, sent by mux_session_confirm */ 472 return 0; 473} 474 475static int 476process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 477{ 478 debug2("%s: channel %d: alive check", __func__, c->self); 479 480 /* prepare reply */ 481 buffer_put_int(r, MUX_S_ALIVE); 482 buffer_put_int(r, rid); 483 buffer_put_int(r, (u_int)getpid()); 484 485 return 0; 486} 487 488static int 489process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 490{ 491 debug2("%s: channel %d: terminate request", __func__, c->self); 492 493 if (options.control_master == SSHCTL_MASTER_ASK || 494 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 495 if (!ask_permission("Terminate shared connection to %s? ", 496 host)) { 497 debug2("%s: termination refused by user", __func__); 498 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 499 buffer_put_int(r, rid); 500 buffer_put_cstring(r, "Permission denied"); 501 return 0; 502 } 503 } 504 505 quit_pending = 1; 506 buffer_put_int(r, MUX_S_OK); 507 buffer_put_int(r, rid); 508 /* XXX exit happens too soon - message never makes it to client */ 509 return 0; 510} 511 512static char * 513format_forward(u_int ftype, Forward *fwd) 514{ 515 char *ret; 516 517 switch (ftype) { 518 case MUX_FWD_LOCAL: 519 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 520 (fwd->listen_host == NULL) ? 521 (options.gateway_ports ? "*" : "LOCALHOST") : 522 fwd->listen_host, fwd->listen_port, 523 fwd->connect_host, fwd->connect_port); 524 break; 525 case MUX_FWD_DYNAMIC: 526 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 527 (fwd->listen_host == NULL) ? 528 (options.gateway_ports ? "*" : "LOCALHOST") : 529 fwd->listen_host, fwd->listen_port); 530 break; 531 case MUX_FWD_REMOTE: 532 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 533 (fwd->listen_host == NULL) ? 534 "LOCALHOST" : fwd->listen_host, 535 fwd->listen_port, 536 fwd->connect_host, fwd->connect_port); 537 break; 538 default: 539 fatal("%s: unknown forward type %u", __func__, ftype); 540 } 541 return ret; 542} 543 544static int 545compare_host(const char *a, const char *b) 546{ 547 if (a == NULL && b == NULL) 548 return 1; 549 if (a == NULL || b == NULL) 550 return 0; 551 return strcmp(a, b) == 0; 552} 553 554static int 555compare_forward(Forward *a, Forward *b) 556{ 557 if (!compare_host(a->listen_host, b->listen_host)) 558 return 0; 559 if (a->listen_port != b->listen_port) 560 return 0; 561 if (!compare_host(a->connect_host, b->connect_host)) 562 return 0; 563 if (a->connect_port != b->connect_port) 564 return 0; 565 566 return 1; 567} 568 569static void 570mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 571{ 572 struct mux_channel_confirm_ctx *fctx = ctxt; 573 char *failmsg = NULL; 574 Forward *rfwd; 575 Channel *c; 576 Buffer out; 577 578 if ((c = channel_by_id(fctx->cid)) == NULL) { 579 /* no channel for reply */ 580 error("%s: unknown channel", __func__); 581 return; 582 } 583 buffer_init(&out); 584 if (fctx->fid >= options.num_remote_forwards) { 585 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 586 goto fail; 587 } 588 rfwd = &options.remote_forwards[fctx->fid]; 589 debug("%s: %s for: listen %d, connect %s:%d", __func__, 590 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 591 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); 592 if (type == SSH2_MSG_REQUEST_SUCCESS) { 593 if (rfwd->listen_port == 0) { 594 rfwd->allocated_port = packet_get_int(); 595 logit("Allocated port %u for mux remote forward" 596 " to %s:%d", rfwd->allocated_port, 597 rfwd->connect_host, rfwd->connect_port); 598 buffer_put_int(&out, MUX_S_REMOTE_PORT); 599 buffer_put_int(&out, fctx->rid); 600 buffer_put_int(&out, rfwd->allocated_port); 601 channel_update_permitted_opens(rfwd->handle, 602 rfwd->allocated_port); 603 } else { 604 buffer_put_int(&out, MUX_S_OK); 605 buffer_put_int(&out, fctx->rid); 606 } 607 goto out; 608 } else { 609 if (rfwd->listen_port == 0) 610 channel_update_permitted_opens(rfwd->handle, -1); 611 xasprintf(&failmsg, "remote port forwarding failed for " 612 "listen port %d", rfwd->listen_port); 613 } 614 fail: 615 error("%s: %s", __func__, failmsg); 616 buffer_put_int(&out, MUX_S_FAILURE); 617 buffer_put_int(&out, fctx->rid); 618 buffer_put_cstring(&out, failmsg); 619 free(failmsg); 620 out: 621 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 622 buffer_free(&out); 623 if (c->mux_pause <= 0) 624 fatal("%s: mux_pause %d", __func__, c->mux_pause); 625 c->mux_pause = 0; /* start processing messages again */ 626} 627 628static int 629process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 630{ 631 Forward fwd; 632 char *fwd_desc = NULL; 633 u_int ftype; 634 u_int lport, cport; 635 int i, ret = 0, freefwd = 1; 636 637 memset(&fwd, 0, sizeof(fwd)); 638 639 if (buffer_get_int_ret(&ftype, m) != 0 || 640 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 641 buffer_get_int_ret(&lport, m) != 0 || 642 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 643 buffer_get_int_ret(&cport, m) != 0 || 644 lport > 65535 || cport > 65535) { 645 error("%s: malformed message", __func__); 646 ret = -1; 647 goto out; 648 } 649 fwd.listen_port = lport; 650 fwd.connect_port = cport; 651 if (*fwd.listen_host == '\0') { 652 free(fwd.listen_host); 653 fwd.listen_host = NULL; 654 } 655 if (*fwd.connect_host == '\0') { 656 free(fwd.connect_host); 657 fwd.connect_host = NULL; 658 } 659 660 debug2("%s: channel %d: request %s", __func__, c->self, 661 (fwd_desc = format_forward(ftype, &fwd))); 662 663 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 664 ftype != MUX_FWD_DYNAMIC) { 665 logit("%s: invalid forwarding type %u", __func__, ftype); 666 invalid: 667 free(fwd.listen_host); 668 free(fwd.connect_host); 669 buffer_put_int(r, MUX_S_FAILURE); 670 buffer_put_int(r, rid); 671 buffer_put_cstring(r, "Invalid forwarding request"); 672 return 0; 673 } 674 if (fwd.listen_port >= 65536) { 675 logit("%s: invalid listen port %u", __func__, 676 fwd.listen_port); 677 goto invalid; 678 } 679 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC && 680 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 681 logit("%s: invalid connect port %u", __func__, 682 fwd.connect_port); 683 goto invalid; 684 } 685 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) { 686 logit("%s: missing connect host", __func__); 687 goto invalid; 688 } 689 690 /* Skip forwards that have already been requested */ 691 switch (ftype) { 692 case MUX_FWD_LOCAL: 693 case MUX_FWD_DYNAMIC: 694 for (i = 0; i < options.num_local_forwards; i++) { 695 if (compare_forward(&fwd, 696 options.local_forwards + i)) { 697 exists: 698 debug2("%s: found existing forwarding", 699 __func__); 700 buffer_put_int(r, MUX_S_OK); 701 buffer_put_int(r, rid); 702 goto out; 703 } 704 } 705 break; 706 case MUX_FWD_REMOTE: 707 for (i = 0; i < options.num_remote_forwards; i++) { 708 if (compare_forward(&fwd, 709 options.remote_forwards + i)) { 710 if (fwd.listen_port != 0) 711 goto exists; 712 debug2("%s: found allocated port", 713 __func__); 714 buffer_put_int(r, MUX_S_REMOTE_PORT); 715 buffer_put_int(r, rid); 716 buffer_put_int(r, 717 options.remote_forwards[i].allocated_port); 718 goto out; 719 } 720 } 721 break; 722 } 723 724 if (options.control_master == SSHCTL_MASTER_ASK || 725 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 726 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 727 debug2("%s: forwarding refused by user", __func__); 728 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 729 buffer_put_int(r, rid); 730 buffer_put_cstring(r, "Permission denied"); 731 goto out; 732 } 733 } 734 735 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 736 if (!channel_setup_local_fwd_listener(fwd.listen_host, 737 fwd.listen_port, fwd.connect_host, fwd.connect_port, 738 options.gateway_ports)) { 739 fail: 740 logit("slave-requested %s failed", fwd_desc); 741 buffer_put_int(r, MUX_S_FAILURE); 742 buffer_put_int(r, rid); 743 buffer_put_cstring(r, "Port forwarding failed"); 744 goto out; 745 } 746 add_local_forward(&options, &fwd); 747 freefwd = 0; 748 } else { 749 struct mux_channel_confirm_ctx *fctx; 750 751 fwd.handle = channel_request_remote_forwarding(fwd.listen_host, 752 fwd.listen_port, fwd.connect_host, fwd.connect_port); 753 if (fwd.handle < 0) 754 goto fail; 755 add_remote_forward(&options, &fwd); 756 fctx = xcalloc(1, sizeof(*fctx)); 757 fctx->cid = c->self; 758 fctx->rid = rid; 759 fctx->fid = options.num_remote_forwards - 1; 760 client_register_global_confirm(mux_confirm_remote_forward, 761 fctx); 762 freefwd = 0; 763 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 764 /* delayed reply in mux_confirm_remote_forward */ 765 goto out; 766 } 767 buffer_put_int(r, MUX_S_OK); 768 buffer_put_int(r, rid); 769 out: 770 free(fwd_desc); 771 if (freefwd) { 772 free(fwd.listen_host); 773 free(fwd.connect_host); 774 } 775 return ret; 776} 777 778static int 779process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 780{ 781 Forward fwd, *found_fwd; 782 char *fwd_desc = NULL; 783 const char *error_reason = NULL; 784 u_int ftype; 785 int i, listen_port, ret = 0; 786 u_int lport, cport; 787 788 memset(&fwd, 0, sizeof(fwd)); 789 790 if (buffer_get_int_ret(&ftype, m) != 0 || 791 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 792 buffer_get_int_ret(&lport, m) != 0 || 793 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 794 buffer_get_int_ret(&cport, m) != 0 || 795 lport > 65535 || cport > 65535) { 796 error("%s: malformed message", __func__); 797 ret = -1; 798 goto out; 799 } 800 fwd.listen_port = lport; 801 fwd.connect_port = cport; 802 803 if (*fwd.listen_host == '\0') { 804 free(fwd.listen_host); 805 fwd.listen_host = NULL; 806 } 807 if (*fwd.connect_host == '\0') { 808 free(fwd.connect_host); 809 fwd.connect_host = NULL; 810 } 811 812 debug2("%s: channel %d: request cancel %s", __func__, c->self, 813 (fwd_desc = format_forward(ftype, &fwd))); 814 815 /* make sure this has been requested */ 816 found_fwd = NULL; 817 switch (ftype) { 818 case MUX_FWD_LOCAL: 819 case MUX_FWD_DYNAMIC: 820 for (i = 0; i < options.num_local_forwards; i++) { 821 if (compare_forward(&fwd, 822 options.local_forwards + i)) { 823 found_fwd = options.local_forwards + i; 824 break; 825 } 826 } 827 break; 828 case MUX_FWD_REMOTE: 829 for (i = 0; i < options.num_remote_forwards; i++) { 830 if (compare_forward(&fwd, 831 options.remote_forwards + i)) { 832 found_fwd = options.remote_forwards + i; 833 break; 834 } 835 } 836 break; 837 } 838 839 if (found_fwd == NULL) 840 error_reason = "port not forwarded"; 841 else if (ftype == MUX_FWD_REMOTE) { 842 /* 843 * This shouldn't fail unless we confused the host/port 844 * between options.remote_forwards and permitted_opens. 845 * However, for dynamic allocated listen ports we need 846 * to lookup the actual listen port. 847 */ 848 listen_port = (fwd.listen_port == 0) ? 849 found_fwd->allocated_port : fwd.listen_port; 850 if (channel_request_rforward_cancel(fwd.listen_host, 851 listen_port) == -1) 852 error_reason = "port not in permitted opens"; 853 } else { /* local and dynamic forwards */ 854 /* Ditto */ 855 if (channel_cancel_lport_listener(fwd.listen_host, 856 fwd.listen_port, fwd.connect_port, 857 options.gateway_ports) == -1) 858 error_reason = "port not found"; 859 } 860 861 if (error_reason == NULL) { 862 buffer_put_int(r, MUX_S_OK); 863 buffer_put_int(r, rid); 864 865 free(found_fwd->listen_host); 866 free(found_fwd->connect_host); 867 found_fwd->listen_host = found_fwd->connect_host = NULL; 868 found_fwd->listen_port = found_fwd->connect_port = 0; 869 } else { 870 buffer_put_int(r, MUX_S_FAILURE); 871 buffer_put_int(r, rid); 872 buffer_put_cstring(r, error_reason); 873 } 874 out: 875 free(fwd_desc); 876 free(fwd.listen_host); 877 free(fwd.connect_host); 878 879 return ret; 880} 881 882static int 883process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 884{ 885 Channel *nc; 886 char *reserved, *chost; 887 u_int cport, i, j; 888 int new_fd[2]; 889 890 chost = reserved = NULL; 891 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 892 (chost = buffer_get_string_ret(m, NULL)) == NULL || 893 buffer_get_int_ret(&cport, m) != 0) { 894 free(reserved); 895 free(chost); 896 error("%s: malformed message", __func__); 897 return -1; 898 } 899 free(reserved); 900 901 debug2("%s: channel %d: request stdio fwd to %s:%u", 902 __func__, c->self, chost, cport); 903 904 /* Gather fds from client */ 905 for(i = 0; i < 2; i++) { 906 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 907 error("%s: failed to receive fd %d from slave", 908 __func__, i); 909 for (j = 0; j < i; j++) 910 close(new_fd[j]); 911 free(chost); 912 913 /* prepare reply */ 914 buffer_put_int(r, MUX_S_FAILURE); 915 buffer_put_int(r, rid); 916 buffer_put_cstring(r, 917 "did not receive file descriptors"); 918 return -1; 919 } 920 } 921 922 debug3("%s: got fds stdin %d, stdout %d", __func__, 923 new_fd[0], new_fd[1]); 924 925 /* XXX support multiple child sessions in future */ 926 if (c->remote_id != -1) { 927 debug2("%s: session already open", __func__); 928 /* prepare reply */ 929 buffer_put_int(r, MUX_S_FAILURE); 930 buffer_put_int(r, rid); 931 buffer_put_cstring(r, "Multiple sessions not supported"); 932 cleanup: 933 close(new_fd[0]); 934 close(new_fd[1]); 935 free(chost); 936 return 0; 937 } 938 939 if (options.control_master == SSHCTL_MASTER_ASK || 940 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 941 if (!ask_permission("Allow forward to %s:%u? ", 942 chost, cport)) { 943 debug2("%s: stdio fwd refused by user", __func__); 944 /* prepare reply */ 945 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 946 buffer_put_int(r, rid); 947 buffer_put_cstring(r, "Permission denied"); 948 goto cleanup; 949 } 950 } 951 952 /* enable nonblocking unless tty */ 953 if (!isatty(new_fd[0])) 954 set_nonblock(new_fd[0]); 955 if (!isatty(new_fd[1])) 956 set_nonblock(new_fd[1]); 957 958 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 959 960 nc->ctl_chan = c->self; /* link session -> control channel */ 961 c->remote_id = nc->self; /* link control -> session channel */ 962 963 debug2("%s: channel_new: %d linked to control channel %d", 964 __func__, nc->self, nc->ctl_chan); 965 966 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 967 968 /* prepare reply */ 969 /* XXX defer until channel confirmed */ 970 buffer_put_int(r, MUX_S_SESSION_OPENED); 971 buffer_put_int(r, rid); 972 buffer_put_int(r, nc->self); 973 974 return 0; 975} 976 977static int 978process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 979{ 980 debug("%s: channel %d: stop listening", __func__, c->self); 981 982 if (options.control_master == SSHCTL_MASTER_ASK || 983 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 984 if (!ask_permission("Disable further multiplexing on shared " 985 "connection to %s? ", host)) { 986 debug2("%s: stop listen refused by user", __func__); 987 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 988 buffer_put_int(r, rid); 989 buffer_put_cstring(r, "Permission denied"); 990 return 0; 991 } 992 } 993 994 if (mux_listener_channel != NULL) { 995 channel_free(mux_listener_channel); 996 client_stop_mux(); 997 free(options.control_path); 998 options.control_path = NULL; 999 mux_listener_channel = NULL; 1000 muxserver_sock = -1; 1001 } 1002 1003 /* prepare reply */ 1004 buffer_put_int(r, MUX_S_OK); 1005 buffer_put_int(r, rid); 1006 1007 return 0; 1008} 1009 1010/* Channel callbacks fired on read/write from mux slave fd */ 1011static int 1012mux_master_read_cb(Channel *c) 1013{ 1014 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1015 Buffer in, out; 1016 void *ptr; 1017 u_int type, rid, have, i; 1018 int ret = -1; 1019 1020 /* Setup ctx and */ 1021 if (c->mux_ctx == NULL) { 1022 state = xcalloc(1, sizeof(*state)); 1023 c->mux_ctx = state; 1024 channel_register_cleanup(c->self, 1025 mux_master_control_cleanup_cb, 0); 1026 1027 /* Send hello */ 1028 buffer_init(&out); 1029 buffer_put_int(&out, MUX_MSG_HELLO); 1030 buffer_put_int(&out, SSHMUX_VER); 1031 /* no extensions */ 1032 buffer_put_string(&c->output, buffer_ptr(&out), 1033 buffer_len(&out)); 1034 buffer_free(&out); 1035 debug3("%s: channel %d: hello sent", __func__, c->self); 1036 return 0; 1037 } 1038 1039 buffer_init(&in); 1040 buffer_init(&out); 1041 1042 /* Channel code ensures that we receive whole packets */ 1043 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1044 malf: 1045 error("%s: malformed message", __func__); 1046 goto out; 1047 } 1048 buffer_append(&in, ptr, have); 1049 1050 if (buffer_get_int_ret(&type, &in) != 0) 1051 goto malf; 1052 debug3("%s: channel %d packet type 0x%08x len %u", 1053 __func__, c->self, type, buffer_len(&in)); 1054 1055 if (type == MUX_MSG_HELLO) 1056 rid = 0; 1057 else { 1058 if (!state->hello_rcvd) { 1059 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1060 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1061 goto out; 1062 } 1063 if (buffer_get_int_ret(&rid, &in) != 0) 1064 goto malf; 1065 } 1066 1067 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1068 if (type == mux_master_handlers[i].type) { 1069 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1070 break; 1071 } 1072 } 1073 if (mux_master_handlers[i].handler == NULL) { 1074 error("%s: unsupported mux message 0x%08x", __func__, type); 1075 buffer_put_int(&out, MUX_S_FAILURE); 1076 buffer_put_int(&out, rid); 1077 buffer_put_cstring(&out, "unsupported request"); 1078 ret = 0; 1079 } 1080 /* Enqueue reply packet */ 1081 if (buffer_len(&out) != 0) { 1082 buffer_put_string(&c->output, buffer_ptr(&out), 1083 buffer_len(&out)); 1084 } 1085 out: 1086 buffer_free(&in); 1087 buffer_free(&out); 1088 return ret; 1089} 1090 1091void 1092mux_exit_message(Channel *c, int exitval) 1093{ 1094 Buffer m; 1095 Channel *mux_chan; 1096 1097 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1098 exitval); 1099 1100 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1101 fatal("%s: channel %d missing mux channel %d", 1102 __func__, c->self, c->ctl_chan); 1103 1104 /* Append exit message packet to control socket output queue */ 1105 buffer_init(&m); 1106 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1107 buffer_put_int(&m, c->self); 1108 buffer_put_int(&m, exitval); 1109 1110 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1111 buffer_free(&m); 1112} 1113 1114void 1115mux_tty_alloc_failed(Channel *c) 1116{ 1117 Buffer m; 1118 Channel *mux_chan; 1119 1120 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1121 1122 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1123 fatal("%s: channel %d missing mux channel %d", 1124 __func__, c->self, c->ctl_chan); 1125 1126 /* Append exit message packet to control socket output queue */ 1127 buffer_init(&m); 1128 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1129 buffer_put_int(&m, c->self); 1130 1131 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1132 buffer_free(&m); 1133} 1134 1135/* Prepare a mux master to listen on a Unix domain socket. */ 1136void 1137muxserver_listen(void) 1138{ 1139 struct sockaddr_un addr; 1140 socklen_t sun_len; 1141 mode_t old_umask; 1142 char *orig_control_path = options.control_path; 1143 char rbuf[16+1]; 1144 u_int i, r; 1145 1146 if (options.control_path == NULL || 1147 options.control_master == SSHCTL_MASTER_NO) 1148 return; 1149 1150 debug("setting up multiplex master socket"); 1151 1152 /* 1153 * Use a temporary path before listen so we can pseudo-atomically 1154 * establish the listening socket in its final location to avoid 1155 * other processes racing in between bind() and listen() and hitting 1156 * an unready socket. 1157 */ 1158 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1159 r = arc4random_uniform(26+26+10); 1160 rbuf[i] = (r < 26) ? 'a' + r : 1161 (r < 26*2) ? 'A' + r - 26 : 1162 '0' + r - 26 - 26; 1163 } 1164 rbuf[sizeof(rbuf) - 1] = '\0'; 1165 options.control_path = NULL; 1166 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1167 debug3("%s: temporary control path %s", __func__, options.control_path); 1168 1169 memset(&addr, '\0', sizeof(addr)); 1170 addr.sun_family = AF_UNIX; 1171 sun_len = offsetof(struct sockaddr_un, sun_path) + 1172 strlen(options.control_path) + 1; 1173 1174 if (strlcpy(addr.sun_path, options.control_path, 1175 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) { 1176 error("ControlPath \"%s\" too long for Unix domain socket", 1177 options.control_path); 1178 goto disable_mux_master; 1179 } 1180 1181 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1182 fatal("%s socket(): %s", __func__, strerror(errno)); 1183 1184 old_umask = umask(0177); 1185 if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) { 1186 if (errno == EINVAL || errno == EADDRINUSE) { 1187 error("ControlSocket %s already exists, " 1188 "disabling multiplexing", options.control_path); 1189 disable_mux_master: 1190 if (muxserver_sock != -1) { 1191 close(muxserver_sock); 1192 muxserver_sock = -1; 1193 } 1194 free(orig_control_path); 1195 free(options.control_path); 1196 options.control_path = NULL; 1197 options.control_master = SSHCTL_MASTER_NO; 1198 return; 1199 } else 1200 fatal("%s bind(): %s", __func__, strerror(errno)); 1201 } 1202 umask(old_umask); 1203 1204 if (listen(muxserver_sock, 64) == -1) 1205 fatal("%s listen(): %s", __func__, strerror(errno)); 1206 1207 /* Now atomically "move" the mux socket into position */ 1208 if (link(options.control_path, orig_control_path) != 0) { 1209 if (errno != EEXIST) { 1210 fatal("%s: link mux listener %s => %s: %s", __func__, 1211 options.control_path, orig_control_path, 1212 strerror(errno)); 1213 } 1214 error("ControlSocket %s already exists, disabling multiplexing", 1215 orig_control_path); 1216 unlink(options.control_path); 1217 goto disable_mux_master; 1218 } 1219 unlink(options.control_path); 1220 free(options.control_path); 1221 options.control_path = orig_control_path; 1222 1223 set_nonblock(muxserver_sock); 1224 1225 mux_listener_channel = channel_new("mux listener", 1226 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1227 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1228 0, options.control_path, 1); 1229 mux_listener_channel->mux_rcb = mux_master_read_cb; 1230 debug3("%s: mux listener channel %d fd %d", __func__, 1231 mux_listener_channel->self, mux_listener_channel->sock); 1232} 1233 1234/* Callback on open confirmation in mux master for a mux client session. */ 1235static void 1236mux_session_confirm(int id, int success, void *arg) 1237{ 1238 struct mux_session_confirm_ctx *cctx = arg; 1239 const char *display; 1240 Channel *c, *cc; 1241 int i; 1242 Buffer reply; 1243 1244 if (cctx == NULL) 1245 fatal("%s: cctx == NULL", __func__); 1246 if ((c = channel_by_id(id)) == NULL) 1247 fatal("%s: no channel for id %d", __func__, id); 1248 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1249 fatal("%s: channel %d lacks control channel %d", __func__, 1250 id, c->ctl_chan); 1251 1252 if (!success) { 1253 debug3("%s: sending failure reply", __func__); 1254 /* prepare reply */ 1255 buffer_init(&reply); 1256 buffer_put_int(&reply, MUX_S_FAILURE); 1257 buffer_put_int(&reply, cctx->rid); 1258 buffer_put_cstring(&reply, "Session open refused by peer"); 1259 goto done; 1260 } 1261 1262 display = getenv("DISPLAY"); 1263 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1264 char *proto, *data; 1265 1266 /* Get reasonable local authentication information. */ 1267 client_x11_get_proto(display, options.xauth_location, 1268 options.forward_x11_trusted, options.forward_x11_timeout, 1269 &proto, &data); 1270 /* Request forwarding with authentication spoofing. */ 1271 debug("Requesting X11 forwarding with authentication " 1272 "spoofing."); 1273 x11_request_forwarding_with_spoofing(id, display, proto, 1274 data, 1); 1275 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1276 /* XXX exit_on_forward_failure */ 1277 } 1278 1279 if (cctx->want_agent_fwd && options.forward_agent) { 1280 debug("Requesting authentication agent forwarding."); 1281 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1282 packet_send(); 1283 } 1284 1285 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1286 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1287 1288 debug3("%s: sending success reply", __func__); 1289 /* prepare reply */ 1290 buffer_init(&reply); 1291 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1292 buffer_put_int(&reply, cctx->rid); 1293 buffer_put_int(&reply, c->self); 1294 1295 done: 1296 /* Send reply */ 1297 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1298 buffer_free(&reply); 1299 1300 if (cc->mux_pause <= 0) 1301 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1302 cc->mux_pause = 0; /* start processing messages again */ 1303 c->open_confirm_ctx = NULL; 1304 buffer_free(&cctx->cmd); 1305 free(cctx->term); 1306 if (cctx->env != NULL) { 1307 for (i = 0; cctx->env[i] != NULL; i++) 1308 free(cctx->env[i]); 1309 free(cctx->env); 1310 } 1311 free(cctx); 1312} 1313 1314/* ** Multiplexing client support */ 1315 1316/* Exit signal handler */ 1317static void 1318control_client_sighandler(int signo) 1319{ 1320 muxclient_terminate = signo; 1321} 1322 1323/* 1324 * Relay signal handler - used to pass some signals from mux client to 1325 * mux master. 1326 */ 1327static void 1328control_client_sigrelay(int signo) 1329{ 1330 int save_errno = errno; 1331 1332 if (muxserver_pid > 1) 1333 kill(muxserver_pid, signo); 1334 1335 errno = save_errno; 1336} 1337 1338static int 1339mux_client_read(int fd, Buffer *b, u_int need) 1340{ 1341 u_int have; 1342 ssize_t len; 1343 u_char *p; 1344 struct pollfd pfd; 1345 1346 pfd.fd = fd; 1347 pfd.events = POLLIN; 1348 p = buffer_append_space(b, need); 1349 for (have = 0; have < need; ) { 1350 if (muxclient_terminate) { 1351 errno = EINTR; 1352 return -1; 1353 } 1354 len = read(fd, p + have, need - have); 1355 if (len < 0) { 1356 switch (errno) { 1357#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1358 case EWOULDBLOCK: 1359#endif 1360 case EAGAIN: 1361 (void)poll(&pfd, 1, -1); 1362 /* FALLTHROUGH */ 1363 case EINTR: 1364 continue; 1365 default: 1366 return -1; 1367 } 1368 } 1369 if (len == 0) { 1370 errno = EPIPE; 1371 return -1; 1372 } 1373 have += (u_int)len; 1374 } 1375 return 0; 1376} 1377 1378static int 1379mux_client_write_packet(int fd, Buffer *m) 1380{ 1381 Buffer queue; 1382 u_int have, need; 1383 int oerrno, len; 1384 u_char *ptr; 1385 struct pollfd pfd; 1386 1387 pfd.fd = fd; 1388 pfd.events = POLLOUT; 1389 buffer_init(&queue); 1390 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1391 1392 need = buffer_len(&queue); 1393 ptr = buffer_ptr(&queue); 1394 1395 for (have = 0; have < need; ) { 1396 if (muxclient_terminate) { 1397 buffer_free(&queue); 1398 errno = EINTR; 1399 return -1; 1400 } 1401 len = write(fd, ptr + have, need - have); 1402 if (len < 0) { 1403 switch (errno) { 1404#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1405 case EWOULDBLOCK: 1406#endif 1407 case EAGAIN: 1408 (void)poll(&pfd, 1, -1); 1409 /* FALLTHROUGH */ 1410 case EINTR: 1411 continue; 1412 default: 1413 oerrno = errno; 1414 buffer_free(&queue); 1415 errno = oerrno; 1416 return -1; 1417 } 1418 } 1419 if (len == 0) { 1420 buffer_free(&queue); 1421 errno = EPIPE; 1422 return -1; 1423 } 1424 have += (u_int)len; 1425 } 1426 buffer_free(&queue); 1427 return 0; 1428} 1429 1430static int 1431mux_client_read_packet(int fd, Buffer *m) 1432{ 1433 Buffer queue; 1434 u_int need, have; 1435 void *ptr; 1436 int oerrno; 1437 1438 buffer_init(&queue); 1439 if (mux_client_read(fd, &queue, 4) != 0) { 1440 if ((oerrno = errno) == EPIPE) 1441 debug3("%s: read header failed: %s", __func__, 1442 strerror(errno)); 1443 buffer_free(&queue); 1444 errno = oerrno; 1445 return -1; 1446 } 1447 need = get_u32(buffer_ptr(&queue)); 1448 if (mux_client_read(fd, &queue, need) != 0) { 1449 oerrno = errno; 1450 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1451 buffer_free(&queue); 1452 errno = oerrno; 1453 return -1; 1454 } 1455 ptr = buffer_get_string_ptr(&queue, &have); 1456 buffer_append(m, ptr, have); 1457 buffer_free(&queue); 1458 return 0; 1459} 1460 1461static int 1462mux_client_hello_exchange(int fd) 1463{ 1464 Buffer m; 1465 u_int type, ver; 1466 1467 buffer_init(&m); 1468 buffer_put_int(&m, MUX_MSG_HELLO); 1469 buffer_put_int(&m, SSHMUX_VER); 1470 /* no extensions */ 1471 1472 if (mux_client_write_packet(fd, &m) != 0) 1473 fatal("%s: write packet: %s", __func__, strerror(errno)); 1474 1475 buffer_clear(&m); 1476 1477 /* Read their HELLO */ 1478 if (mux_client_read_packet(fd, &m) != 0) { 1479 buffer_free(&m); 1480 return -1; 1481 } 1482 1483 type = buffer_get_int(&m); 1484 if (type != MUX_MSG_HELLO) 1485 fatal("%s: expected HELLO (%u) received %u", 1486 __func__, MUX_MSG_HELLO, type); 1487 ver = buffer_get_int(&m); 1488 if (ver != SSHMUX_VER) 1489 fatal("Unsupported multiplexing protocol version %d " 1490 "(expected %d)", ver, SSHMUX_VER); 1491 debug2("%s: master version %u", __func__, ver); 1492 /* No extensions are presently defined */ 1493 while (buffer_len(&m) > 0) { 1494 char *name = buffer_get_string(&m, NULL); 1495 char *value = buffer_get_string(&m, NULL); 1496 1497 debug2("Unrecognised master extension \"%s\"", name); 1498 free(name); 1499 free(value); 1500 } 1501 buffer_free(&m); 1502 return 0; 1503} 1504 1505static u_int 1506mux_client_request_alive(int fd) 1507{ 1508 Buffer m; 1509 char *e; 1510 u_int pid, type, rid; 1511 1512 debug3("%s: entering", __func__); 1513 1514 buffer_init(&m); 1515 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1516 buffer_put_int(&m, muxclient_request_id); 1517 1518 if (mux_client_write_packet(fd, &m) != 0) 1519 fatal("%s: write packet: %s", __func__, strerror(errno)); 1520 1521 buffer_clear(&m); 1522 1523 /* Read their reply */ 1524 if (mux_client_read_packet(fd, &m) != 0) { 1525 buffer_free(&m); 1526 return 0; 1527 } 1528 1529 type = buffer_get_int(&m); 1530 if (type != MUX_S_ALIVE) { 1531 e = buffer_get_string(&m, NULL); 1532 fatal("%s: master returned error: %s", __func__, e); 1533 } 1534 1535 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1536 fatal("%s: out of sequence reply: my id %u theirs %u", 1537 __func__, muxclient_request_id, rid); 1538 pid = buffer_get_int(&m); 1539 buffer_free(&m); 1540 1541 debug3("%s: done pid = %u", __func__, pid); 1542 1543 muxclient_request_id++; 1544 1545 return pid; 1546} 1547 1548static void 1549mux_client_request_terminate(int fd) 1550{ 1551 Buffer m; 1552 char *e; 1553 u_int type, rid; 1554 1555 debug3("%s: entering", __func__); 1556 1557 buffer_init(&m); 1558 buffer_put_int(&m, MUX_C_TERMINATE); 1559 buffer_put_int(&m, muxclient_request_id); 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 /* Remote end exited already */ 1569 if (errno == EPIPE) { 1570 buffer_free(&m); 1571 return; 1572 } 1573 fatal("%s: read from master failed: %s", 1574 __func__, strerror(errno)); 1575 } 1576 1577 type = buffer_get_int(&m); 1578 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1579 fatal("%s: out of sequence reply: my id %u theirs %u", 1580 __func__, muxclient_request_id, rid); 1581 switch (type) { 1582 case MUX_S_OK: 1583 break; 1584 case MUX_S_PERMISSION_DENIED: 1585 e = buffer_get_string(&m, NULL); 1586 fatal("Master refused termination request: %s", e); 1587 case MUX_S_FAILURE: 1588 e = buffer_get_string(&m, NULL); 1589 fatal("%s: termination request failed: %s", __func__, e); 1590 default: 1591 fatal("%s: unexpected response from master 0x%08x", 1592 __func__, type); 1593 } 1594 buffer_free(&m); 1595 muxclient_request_id++; 1596} 1597 1598static int 1599mux_client_forward(int fd, int cancel_flag, u_int ftype, Forward *fwd) 1600{ 1601 Buffer m; 1602 char *e, *fwd_desc; 1603 u_int type, rid; 1604 1605 fwd_desc = format_forward(ftype, fwd); 1606 debug("Requesting %s %s", 1607 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1608 free(fwd_desc); 1609 1610 buffer_init(&m); 1611 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1612 buffer_put_int(&m, muxclient_request_id); 1613 buffer_put_int(&m, ftype); 1614 buffer_put_cstring(&m, 1615 fwd->listen_host == NULL ? "" : fwd->listen_host); 1616 buffer_put_int(&m, fwd->listen_port); 1617 buffer_put_cstring(&m, 1618 fwd->connect_host == NULL ? "" : fwd->connect_host); 1619 buffer_put_int(&m, fwd->connect_port); 1620 1621 if (mux_client_write_packet(fd, &m) != 0) 1622 fatal("%s: write packet: %s", __func__, strerror(errno)); 1623 1624 buffer_clear(&m); 1625 1626 /* Read their reply */ 1627 if (mux_client_read_packet(fd, &m) != 0) { 1628 buffer_free(&m); 1629 return -1; 1630 } 1631 1632 type = buffer_get_int(&m); 1633 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1634 fatal("%s: out of sequence reply: my id %u theirs %u", 1635 __func__, muxclient_request_id, rid); 1636 switch (type) { 1637 case MUX_S_OK: 1638 break; 1639 case MUX_S_REMOTE_PORT: 1640 if (cancel_flag) 1641 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1642 fwd->allocated_port = buffer_get_int(&m); 1643 logit("Allocated port %u for remote forward to %s:%d", 1644 fwd->allocated_port, 1645 fwd->connect_host ? fwd->connect_host : "", 1646 fwd->connect_port); 1647 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1648 fprintf(stdout, "%u\n", fwd->allocated_port); 1649 break; 1650 case MUX_S_PERMISSION_DENIED: 1651 e = buffer_get_string(&m, NULL); 1652 buffer_free(&m); 1653 error("Master refused forwarding request: %s", e); 1654 return -1; 1655 case MUX_S_FAILURE: 1656 e = buffer_get_string(&m, NULL); 1657 buffer_free(&m); 1658 error("%s: forwarding request failed: %s", __func__, e); 1659 return -1; 1660 default: 1661 fatal("%s: unexpected response from master 0x%08x", 1662 __func__, type); 1663 } 1664 buffer_free(&m); 1665 1666 muxclient_request_id++; 1667 return 0; 1668} 1669 1670static int 1671mux_client_forwards(int fd, int cancel_flag) 1672{ 1673 int i, ret = 0; 1674 1675 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1676 cancel_flag ? "cancel" : "request", 1677 options.num_local_forwards, options.num_remote_forwards); 1678 1679 /* XXX ExitOnForwardingFailure */ 1680 for (i = 0; i < options.num_local_forwards; i++) { 1681 if (mux_client_forward(fd, cancel_flag, 1682 options.local_forwards[i].connect_port == 0 ? 1683 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1684 options.local_forwards + i) != 0) 1685 ret = -1; 1686 } 1687 for (i = 0; i < options.num_remote_forwards; i++) { 1688 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1689 options.remote_forwards + i) != 0) 1690 ret = -1; 1691 } 1692 return ret; 1693} 1694 1695static int 1696mux_client_request_session(int fd) 1697{ 1698 Buffer m; 1699 char *e, *term; 1700 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1701 extern char **environ; 1702 int devnull, rawmode; 1703 1704 debug3("%s: entering", __func__); 1705 1706 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1707 error("%s: master alive request failed", __func__); 1708 return -1; 1709 } 1710 1711 signal(SIGPIPE, SIG_IGN); 1712 1713 if (stdin_null_flag) { 1714 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1715 fatal("open(/dev/null): %s", strerror(errno)); 1716 if (dup2(devnull, STDIN_FILENO) == -1) 1717 fatal("dup2: %s", strerror(errno)); 1718 if (devnull > STDERR_FILENO) 1719 close(devnull); 1720 } 1721 1722 term = getenv("TERM"); 1723 1724 buffer_init(&m); 1725 buffer_put_int(&m, MUX_C_NEW_SESSION); 1726 buffer_put_int(&m, muxclient_request_id); 1727 buffer_put_cstring(&m, ""); /* reserved */ 1728 buffer_put_int(&m, tty_flag); 1729 buffer_put_int(&m, options.forward_x11); 1730 buffer_put_int(&m, options.forward_agent); 1731 buffer_put_int(&m, subsystem_flag); 1732 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1733 0xffffffff : (u_int)options.escape_char); 1734 buffer_put_cstring(&m, term == NULL ? "" : term); 1735 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1736 1737 if (options.num_send_env > 0 && environ != NULL) { 1738 /* Pass environment */ 1739 for (i = 0; environ[i] != NULL; i++) { 1740 if (env_permitted(environ[i])) { 1741 buffer_put_cstring(&m, environ[i]); 1742 } 1743 } 1744 } 1745 1746 if (mux_client_write_packet(fd, &m) != 0) 1747 fatal("%s: write packet: %s", __func__, strerror(errno)); 1748 1749 /* Send the stdio file descriptors */ 1750 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1751 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1752 mm_send_fd(fd, STDERR_FILENO) == -1) 1753 fatal("%s: send fds failed", __func__); 1754 1755 debug3("%s: session request sent", __func__); 1756 1757 /* Read their reply */ 1758 buffer_clear(&m); 1759 if (mux_client_read_packet(fd, &m) != 0) { 1760 error("%s: read from master failed: %s", 1761 __func__, strerror(errno)); 1762 buffer_free(&m); 1763 return -1; 1764 } 1765 1766 type = buffer_get_int(&m); 1767 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1768 fatal("%s: out of sequence reply: my id %u theirs %u", 1769 __func__, muxclient_request_id, rid); 1770 switch (type) { 1771 case MUX_S_SESSION_OPENED: 1772 sid = buffer_get_int(&m); 1773 debug("%s: master session id: %u", __func__, sid); 1774 break; 1775 case MUX_S_PERMISSION_DENIED: 1776 e = buffer_get_string(&m, NULL); 1777 buffer_free(&m); 1778 error("Master refused session request: %s", e); 1779 return -1; 1780 case MUX_S_FAILURE: 1781 e = buffer_get_string(&m, NULL); 1782 buffer_free(&m); 1783 error("%s: session request failed: %s", __func__, e); 1784 return -1; 1785 default: 1786 buffer_free(&m); 1787 error("%s: unexpected response from master 0x%08x", 1788 __func__, type); 1789 return -1; 1790 } 1791 muxclient_request_id++; 1792 1793 signal(SIGHUP, control_client_sighandler); 1794 signal(SIGINT, control_client_sighandler); 1795 signal(SIGTERM, control_client_sighandler); 1796 signal(SIGWINCH, control_client_sigrelay); 1797 1798 rawmode = tty_flag; 1799 if (tty_flag) 1800 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1801 1802 /* 1803 * Stick around until the controlee closes the client_fd. 1804 * Before it does, it is expected to write an exit message. 1805 * This process must read the value and wait for the closure of 1806 * the client_fd; if this one closes early, the multiplex master will 1807 * terminate early too (possibly losing data). 1808 */ 1809 for (exitval = 255, exitval_seen = 0;;) { 1810 buffer_clear(&m); 1811 if (mux_client_read_packet(fd, &m) != 0) 1812 break; 1813 type = buffer_get_int(&m); 1814 switch (type) { 1815 case MUX_S_TTY_ALLOC_FAIL: 1816 if ((esid = buffer_get_int(&m)) != sid) 1817 fatal("%s: tty alloc fail on unknown session: " 1818 "my id %u theirs %u", 1819 __func__, sid, esid); 1820 leave_raw_mode(options.request_tty == 1821 REQUEST_TTY_FORCE); 1822 rawmode = 0; 1823 continue; 1824 case MUX_S_EXIT_MESSAGE: 1825 if ((esid = buffer_get_int(&m)) != sid) 1826 fatal("%s: exit on unknown session: " 1827 "my id %u theirs %u", 1828 __func__, sid, esid); 1829 if (exitval_seen) 1830 fatal("%s: exitval sent twice", __func__); 1831 exitval = buffer_get_int(&m); 1832 exitval_seen = 1; 1833 continue; 1834 default: 1835 e = buffer_get_string(&m, NULL); 1836 fatal("%s: master returned error: %s", __func__, e); 1837 } 1838 } 1839 1840 close(fd); 1841 if (rawmode) 1842 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1843 1844 if (muxclient_terminate) { 1845 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1846 exitval = 255; 1847 } else if (!exitval_seen) { 1848 debug2("Control master terminated unexpectedly"); 1849 exitval = 255; 1850 } else 1851 debug2("Received exit status from master %d", exitval); 1852 1853 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1854 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1855 1856 exit(exitval); 1857} 1858 1859static int 1860mux_client_request_stdio_fwd(int fd) 1861{ 1862 Buffer m; 1863 char *e; 1864 u_int type, rid, sid; 1865 int devnull; 1866 1867 debug3("%s: entering", __func__); 1868 1869 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1870 error("%s: master alive request failed", __func__); 1871 return -1; 1872 } 1873 1874 signal(SIGPIPE, SIG_IGN); 1875 1876 if (stdin_null_flag) { 1877 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1878 fatal("open(/dev/null): %s", strerror(errno)); 1879 if (dup2(devnull, STDIN_FILENO) == -1) 1880 fatal("dup2: %s", strerror(errno)); 1881 if (devnull > STDERR_FILENO) 1882 close(devnull); 1883 } 1884 1885 buffer_init(&m); 1886 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1887 buffer_put_int(&m, muxclient_request_id); 1888 buffer_put_cstring(&m, ""); /* reserved */ 1889 buffer_put_cstring(&m, stdio_forward_host); 1890 buffer_put_int(&m, stdio_forward_port); 1891 1892 if (mux_client_write_packet(fd, &m) != 0) 1893 fatal("%s: write packet: %s", __func__, strerror(errno)); 1894 1895 /* Send the stdio file descriptors */ 1896 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1897 mm_send_fd(fd, STDOUT_FILENO) == -1) 1898 fatal("%s: send fds failed", __func__); 1899 1900 debug3("%s: stdio forward request sent", __func__); 1901 1902 /* Read their reply */ 1903 buffer_clear(&m); 1904 1905 if (mux_client_read_packet(fd, &m) != 0) { 1906 error("%s: read from master failed: %s", 1907 __func__, strerror(errno)); 1908 buffer_free(&m); 1909 return -1; 1910 } 1911 1912 type = buffer_get_int(&m); 1913 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1914 fatal("%s: out of sequence reply: my id %u theirs %u", 1915 __func__, muxclient_request_id, rid); 1916 switch (type) { 1917 case MUX_S_SESSION_OPENED: 1918 sid = buffer_get_int(&m); 1919 debug("%s: master session id: %u", __func__, sid); 1920 break; 1921 case MUX_S_PERMISSION_DENIED: 1922 e = buffer_get_string(&m, NULL); 1923 buffer_free(&m); 1924 fatal("Master refused stdio forwarding request: %s", e); 1925 case MUX_S_FAILURE: 1926 e = buffer_get_string(&m, NULL); 1927 buffer_free(&m); 1928 fatal("%s: stdio forwarding request failed: %s", __func__, e); 1929 default: 1930 buffer_free(&m); 1931 error("%s: unexpected response from master 0x%08x", 1932 __func__, type); 1933 return -1; 1934 } 1935 muxclient_request_id++; 1936 1937 signal(SIGHUP, control_client_sighandler); 1938 signal(SIGINT, control_client_sighandler); 1939 signal(SIGTERM, control_client_sighandler); 1940 signal(SIGWINCH, control_client_sigrelay); 1941 1942 /* 1943 * Stick around until the controlee closes the client_fd. 1944 */ 1945 buffer_clear(&m); 1946 if (mux_client_read_packet(fd, &m) != 0) { 1947 if (errno == EPIPE || 1948 (errno == EINTR && muxclient_terminate != 0)) 1949 return 0; 1950 fatal("%s: mux_client_read_packet: %s", 1951 __func__, strerror(errno)); 1952 } 1953 fatal("%s: master returned unexpected message %u", __func__, type); 1954} 1955 1956static void 1957mux_client_request_stop_listening(int fd) 1958{ 1959 Buffer m; 1960 char *e; 1961 u_int type, rid; 1962 1963 debug3("%s: entering", __func__); 1964 1965 buffer_init(&m); 1966 buffer_put_int(&m, MUX_C_STOP_LISTENING); 1967 buffer_put_int(&m, muxclient_request_id); 1968 1969 if (mux_client_write_packet(fd, &m) != 0) 1970 fatal("%s: write packet: %s", __func__, strerror(errno)); 1971 1972 buffer_clear(&m); 1973 1974 /* Read their reply */ 1975 if (mux_client_read_packet(fd, &m) != 0) 1976 fatal("%s: read from master failed: %s", 1977 __func__, strerror(errno)); 1978 1979 type = buffer_get_int(&m); 1980 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1981 fatal("%s: out of sequence reply: my id %u theirs %u", 1982 __func__, muxclient_request_id, rid); 1983 switch (type) { 1984 case MUX_S_OK: 1985 break; 1986 case MUX_S_PERMISSION_DENIED: 1987 e = buffer_get_string(&m, NULL); 1988 fatal("Master refused stop listening request: %s", e); 1989 case MUX_S_FAILURE: 1990 e = buffer_get_string(&m, NULL); 1991 fatal("%s: stop listening request failed: %s", __func__, e); 1992 default: 1993 fatal("%s: unexpected response from master 0x%08x", 1994 __func__, type); 1995 } 1996 buffer_free(&m); 1997 muxclient_request_id++; 1998} 1999 2000/* Multiplex client main loop. */ 2001void 2002muxclient(const char *path) 2003{ 2004 struct sockaddr_un addr; 2005 socklen_t sun_len; 2006 int sock; 2007 u_int pid; 2008 2009 if (muxclient_command == 0) { 2010 if (stdio_forward_host != NULL) 2011 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2012 else 2013 muxclient_command = SSHMUX_COMMAND_OPEN; 2014 } 2015 2016 switch (options.control_master) { 2017 case SSHCTL_MASTER_AUTO: 2018 case SSHCTL_MASTER_AUTO_ASK: 2019 debug("auto-mux: Trying existing master"); 2020 /* FALLTHROUGH */ 2021 case SSHCTL_MASTER_NO: 2022 break; 2023 default: 2024 return; 2025 } 2026 2027 memset(&addr, '\0', sizeof(addr)); 2028 addr.sun_family = AF_UNIX; 2029 sun_len = offsetof(struct sockaddr_un, sun_path) + 2030 strlen(path) + 1; 2031 2032 if (strlcpy(addr.sun_path, path, 2033 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2034 fatal("ControlPath too long"); 2035 2036 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2037 fatal("%s socket(): %s", __func__, strerror(errno)); 2038 2039 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2040 switch (muxclient_command) { 2041 case SSHMUX_COMMAND_OPEN: 2042 case SSHMUX_COMMAND_STDIO_FWD: 2043 break; 2044 default: 2045 fatal("Control socket connect(%.100s): %s", path, 2046 strerror(errno)); 2047 } 2048 if (errno == ECONNREFUSED && 2049 options.control_master != SSHCTL_MASTER_NO) { 2050 debug("Stale control socket %.100s, unlinking", path); 2051 unlink(path); 2052 } else if (errno == ENOENT) { 2053 debug("Control socket \"%.100s\" does not exist", path); 2054 } else { 2055 error("Control socket connect(%.100s): %s", path, 2056 strerror(errno)); 2057 } 2058 close(sock); 2059 return; 2060 } 2061 set_nonblock(sock); 2062 2063 if (mux_client_hello_exchange(sock) != 0) { 2064 error("%s: master hello exchange failed", __func__); 2065 close(sock); 2066 return; 2067 } 2068 2069 switch (muxclient_command) { 2070 case SSHMUX_COMMAND_ALIVE_CHECK: 2071 if ((pid = mux_client_request_alive(sock)) == 0) 2072 fatal("%s: master alive check failed", __func__); 2073 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2074 exit(0); 2075 case SSHMUX_COMMAND_TERMINATE: 2076 mux_client_request_terminate(sock); 2077 fprintf(stderr, "Exit request sent.\r\n"); 2078 exit(0); 2079 case SSHMUX_COMMAND_FORWARD: 2080 if (mux_client_forwards(sock, 0) != 0) 2081 fatal("%s: master forward request failed", __func__); 2082 exit(0); 2083 case SSHMUX_COMMAND_OPEN: 2084 if (mux_client_forwards(sock, 0) != 0) { 2085 error("%s: master forward request failed", __func__); 2086 return; 2087 } 2088 mux_client_request_session(sock); 2089 return; 2090 case SSHMUX_COMMAND_STDIO_FWD: 2091 mux_client_request_stdio_fwd(sock); 2092 exit(0); 2093 case SSHMUX_COMMAND_STOP: 2094 mux_client_request_stop_listening(sock); 2095 fprintf(stderr, "Stop listening request sent.\r\n"); 2096 exit(0); 2097 case SSHMUX_COMMAND_CANCEL_FWD: 2098 if (mux_client_forwards(sock, 1) != 0) 2099 error("%s: master cancel forward request failed", 2100 __func__); 2101 exit(0); 2102 default: 2103 fatal("unrecognised muxclient_command %d", muxclient_command); 2104 } 2105} 2106