mux.c revision 295367
1/* $OpenBSD: mux.c,v 1.54 2015/08/19 23:18:26 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 295367 2016-02-07 11:38:54Z des $"); 35 36#include <sys/types.h> 37#include <sys/stat.h> 38#include <sys/socket.h> 39#include <sys/un.h> 40 41#include <errno.h> 42#include <fcntl.h> 43#include <signal.h> 44#include <stdarg.h> 45#include <stddef.h> 46#include <stdlib.h> 47#include <stdio.h> 48#include <string.h> 49#include <unistd.h> 50#ifdef HAVE_PATHS_H 51#include <paths.h> 52#endif 53 54#ifdef HAVE_POLL_H 55#include <poll.h> 56#else 57# ifdef HAVE_SYS_POLL_H 58# include <sys/poll.h> 59# endif 60#endif 61 62#ifdef HAVE_UTIL_H 63# include <util.h> 64#endif 65 66#include "openbsd-compat/sys-queue.h" 67#include "xmalloc.h" 68#include "log.h" 69#include "ssh.h" 70#include "ssh2.h" 71#include "pathnames.h" 72#include "misc.h" 73#include "match.h" 74#include "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 stdio fwd open confirmation callback */ 109struct mux_stdio_confirm_ctx { 110 u_int rid; 111}; 112 113/* Context for global channel callback */ 114struct mux_channel_confirm_ctx { 115 u_int cid; /* channel id */ 116 u_int rid; /* request id */ 117 int fid; /* forward id */ 118}; 119 120/* fd to control socket */ 121int muxserver_sock = -1; 122 123/* client request id */ 124u_int muxclient_request_id = 0; 125 126/* Multiplexing control command */ 127u_int muxclient_command = 0; 128 129/* Set when signalled. */ 130static volatile sig_atomic_t muxclient_terminate = 0; 131 132/* PID of multiplex server */ 133static u_int muxserver_pid = 0; 134 135static Channel *mux_listener_channel = NULL; 136 137struct mux_master_state { 138 int hello_rcvd; 139}; 140 141/* mux protocol messages */ 142#define MUX_MSG_HELLO 0x00000001 143#define MUX_C_NEW_SESSION 0x10000002 144#define MUX_C_ALIVE_CHECK 0x10000004 145#define MUX_C_TERMINATE 0x10000005 146#define MUX_C_OPEN_FWD 0x10000006 147#define MUX_C_CLOSE_FWD 0x10000007 148#define MUX_C_NEW_STDIO_FWD 0x10000008 149#define MUX_C_STOP_LISTENING 0x10000009 150#define MUX_S_OK 0x80000001 151#define MUX_S_PERMISSION_DENIED 0x80000002 152#define MUX_S_FAILURE 0x80000003 153#define MUX_S_EXIT_MESSAGE 0x80000004 154#define MUX_S_ALIVE 0x80000005 155#define MUX_S_SESSION_OPENED 0x80000006 156#define MUX_S_REMOTE_PORT 0x80000007 157#define MUX_S_TTY_ALLOC_FAIL 0x80000008 158 159/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 160#define MUX_FWD_LOCAL 1 161#define MUX_FWD_REMOTE 2 162#define MUX_FWD_DYNAMIC 3 163 164static void mux_session_confirm(int, int, void *); 165static void mux_stdio_confirm(int, int, void *); 166 167static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 168static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 169static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 170static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 171static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 172static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 173static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 174static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 175 176static const struct { 177 u_int type; 178 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 179} mux_master_handlers[] = { 180 { MUX_MSG_HELLO, process_mux_master_hello }, 181 { MUX_C_NEW_SESSION, process_mux_new_session }, 182 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 183 { MUX_C_TERMINATE, process_mux_terminate }, 184 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 185 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 186 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 187 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 188 { 0, NULL } 189}; 190 191/* Cleanup callback fired on closure of mux slave _session_ channel */ 192/* ARGSUSED */ 193static void 194mux_master_session_cleanup_cb(int cid, void *unused) 195{ 196 Channel *cc, *c = channel_by_id(cid); 197 198 debug3("%s: entering for channel %d", __func__, cid); 199 if (c == NULL) 200 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 201 if (c->ctl_chan != -1) { 202 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 203 fatal("%s: channel %d missing control channel %d", 204 __func__, c->self, c->ctl_chan); 205 c->ctl_chan = -1; 206 cc->remote_id = -1; 207 chan_rcvd_oclose(cc); 208 } 209 channel_cancel_cleanup(c->self); 210} 211 212/* Cleanup callback fired on closure of mux slave _control_ channel */ 213/* ARGSUSED */ 214static void 215mux_master_control_cleanup_cb(int cid, void *unused) 216{ 217 Channel *sc, *c = channel_by_id(cid); 218 219 debug3("%s: entering for channel %d", __func__, cid); 220 if (c == NULL) 221 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 222 if (c->remote_id != -1) { 223 if ((sc = channel_by_id(c->remote_id)) == NULL) 224 fatal("%s: channel %d missing session channel %d", 225 __func__, c->self, c->remote_id); 226 c->remote_id = -1; 227 sc->ctl_chan = -1; 228 if (sc->type != SSH_CHANNEL_OPEN && 229 sc->type != SSH_CHANNEL_OPENING) { 230 debug2("%s: channel %d: not open", __func__, sc->self); 231 chan_mark_dead(sc); 232 } else { 233 if (sc->istate == CHAN_INPUT_OPEN) 234 chan_read_failed(sc); 235 if (sc->ostate == CHAN_OUTPUT_OPEN) 236 chan_write_failed(sc); 237 } 238 } 239 channel_cancel_cleanup(c->self); 240} 241 242/* Check mux client environment variables before passing them to mux master. */ 243static int 244env_permitted(char *env) 245{ 246 int i, ret; 247 char name[1024], *cp; 248 249 if ((cp = strchr(env, '=')) == NULL || cp == env) 250 return 0; 251 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 252 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 253 error("env_permitted: name '%.100s...' too long", env); 254 return 0; 255 } 256 257 for (i = 0; i < options.num_send_env; i++) 258 if (match_pattern(name, options.send_env[i])) 259 return 1; 260 261 return 0; 262} 263 264/* Mux master protocol message handlers */ 265 266static int 267process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 268{ 269 u_int ver; 270 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 271 272 if (state == NULL) 273 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 274 if (state->hello_rcvd) { 275 error("%s: HELLO received twice", __func__); 276 return -1; 277 } 278 if (buffer_get_int_ret(&ver, m) != 0) { 279 malf: 280 error("%s: malformed message", __func__); 281 return -1; 282 } 283 if (ver != SSHMUX_VER) { 284 error("Unsupported multiplexing protocol version %d " 285 "(expected %d)", ver, SSHMUX_VER); 286 return -1; 287 } 288 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 289 290 /* No extensions are presently defined */ 291 while (buffer_len(m) > 0) { 292 char *name = buffer_get_string_ret(m, NULL); 293 char *value = buffer_get_string_ret(m, NULL); 294 295 if (name == NULL || value == NULL) { 296 free(name); 297 free(value); 298 goto malf; 299 } 300 debug2("Unrecognised slave extension \"%s\"", name); 301 free(name); 302 free(value); 303 } 304 state->hello_rcvd = 1; 305 return 0; 306} 307 308static int 309process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 310{ 311 Channel *nc; 312 struct mux_session_confirm_ctx *cctx; 313 char *reserved, *cmd, *cp; 314 u_int i, j, len, env_len, escape_char, window, packetmax; 315 int new_fd[3]; 316 317 /* Reply for SSHMUX_COMMAND_OPEN */ 318 cctx = xcalloc(1, sizeof(*cctx)); 319 cctx->term = NULL; 320 cctx->rid = rid; 321 cmd = reserved = NULL; 322 cctx->env = NULL; 323 env_len = 0; 324 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 325 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 326 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 327 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 328 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 329 buffer_get_int_ret(&escape_char, m) != 0 || 330 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 331 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 332 malf: 333 free(cmd); 334 free(reserved); 335 for (j = 0; j < env_len; j++) 336 free(cctx->env[j]); 337 free(cctx->env); 338 free(cctx->term); 339 free(cctx); 340 error("%s: malformed message", __func__); 341 return -1; 342 } 343 free(reserved); 344 reserved = NULL; 345 346 while (buffer_len(m) > 0) { 347#define MUX_MAX_ENV_VARS 4096 348 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 349 goto malf; 350 if (!env_permitted(cp)) { 351 free(cp); 352 continue; 353 } 354 cctx->env = xreallocarray(cctx->env, env_len + 2, 355 sizeof(*cctx->env)); 356 cctx->env[env_len++] = cp; 357 cctx->env[env_len] = NULL; 358 if (env_len > MUX_MAX_ENV_VARS) { 359 error(">%d environment variables received, ignoring " 360 "additional", MUX_MAX_ENV_VARS); 361 break; 362 } 363 } 364 365 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 366 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 367 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 368 cctx->want_subsys, cctx->term, cmd, env_len); 369 370 buffer_init(&cctx->cmd); 371 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 372 free(cmd); 373 cmd = NULL; 374 375 /* Gather fds from client */ 376 for(i = 0; i < 3; i++) { 377 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 378 error("%s: failed to receive fd %d from slave", 379 __func__, i); 380 for (j = 0; j < i; j++) 381 close(new_fd[j]); 382 for (j = 0; j < env_len; j++) 383 free(cctx->env[j]); 384 free(cctx->env); 385 free(cctx->term); 386 buffer_free(&cctx->cmd); 387 free(cctx); 388 389 /* prepare reply */ 390 buffer_put_int(r, MUX_S_FAILURE); 391 buffer_put_int(r, rid); 392 buffer_put_cstring(r, 393 "did not receive file descriptors"); 394 return -1; 395 } 396 } 397 398 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 399 new_fd[0], new_fd[1], new_fd[2]); 400 401 /* XXX support multiple child sessions in future */ 402 if (c->remote_id != -1) { 403 debug2("%s: session already open", __func__); 404 /* prepare reply */ 405 buffer_put_int(r, MUX_S_FAILURE); 406 buffer_put_int(r, rid); 407 buffer_put_cstring(r, "Multiple sessions not supported"); 408 cleanup: 409 close(new_fd[0]); 410 close(new_fd[1]); 411 close(new_fd[2]); 412 free(cctx->term); 413 if (env_len != 0) { 414 for (i = 0; i < env_len; i++) 415 free(cctx->env[i]); 416 free(cctx->env); 417 } 418 buffer_free(&cctx->cmd); 419 free(cctx); 420 return 0; 421 } 422 423 if (options.control_master == SSHCTL_MASTER_ASK || 424 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 425 if (!ask_permission("Allow shared connection to %s? ", host)) { 426 debug2("%s: session refused by user", __func__); 427 /* prepare reply */ 428 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 429 buffer_put_int(r, rid); 430 buffer_put_cstring(r, "Permission denied"); 431 goto cleanup; 432 } 433 } 434 435 /* Try to pick up ttymodes from client before it goes raw */ 436 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 437 error("%s: tcgetattr: %s", __func__, strerror(errno)); 438 439 /* enable nonblocking unless tty */ 440 if (!isatty(new_fd[0])) 441 set_nonblock(new_fd[0]); 442 if (!isatty(new_fd[1])) 443 set_nonblock(new_fd[1]); 444 if (!isatty(new_fd[2])) 445 set_nonblock(new_fd[2]); 446 447 window = CHAN_SES_WINDOW_DEFAULT; 448 packetmax = CHAN_SES_PACKET_DEFAULT; 449 if (cctx->want_tty) { 450 window >>= 1; 451 packetmax >>= 1; 452 } 453 454 nc = channel_new("session", SSH_CHANNEL_OPENING, 455 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 456 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 457 458 nc->ctl_chan = c->self; /* link session -> control channel */ 459 c->remote_id = nc->self; /* link control -> session channel */ 460 461 if (cctx->want_tty && escape_char != 0xffffffff) { 462 channel_register_filter(nc->self, 463 client_simple_escape_filter, NULL, 464 client_filter_cleanup, 465 client_new_escape_filter_ctx((int)escape_char)); 466 } 467 468 debug2("%s: channel_new: %d linked to control channel %d", 469 __func__, nc->self, nc->ctl_chan); 470 471 channel_send_open(nc->self); 472 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 473 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 474 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 475 476 /* reply is deferred, sent by mux_session_confirm */ 477 return 0; 478} 479 480static int 481process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 482{ 483 debug2("%s: channel %d: alive check", __func__, c->self); 484 485 /* prepare reply */ 486 buffer_put_int(r, MUX_S_ALIVE); 487 buffer_put_int(r, rid); 488 buffer_put_int(r, (u_int)getpid()); 489 490 return 0; 491} 492 493static int 494process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 495{ 496 debug2("%s: channel %d: terminate request", __func__, c->self); 497 498 if (options.control_master == SSHCTL_MASTER_ASK || 499 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 500 if (!ask_permission("Terminate shared connection to %s? ", 501 host)) { 502 debug2("%s: termination refused by user", __func__); 503 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 504 buffer_put_int(r, rid); 505 buffer_put_cstring(r, "Permission denied"); 506 return 0; 507 } 508 } 509 510 quit_pending = 1; 511 buffer_put_int(r, MUX_S_OK); 512 buffer_put_int(r, rid); 513 /* XXX exit happens too soon - message never makes it to client */ 514 return 0; 515} 516 517static char * 518format_forward(u_int ftype, struct Forward *fwd) 519{ 520 char *ret; 521 522 switch (ftype) { 523 case MUX_FWD_LOCAL: 524 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 525 (fwd->listen_path != NULL) ? fwd->listen_path : 526 (fwd->listen_host == NULL) ? 527 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 528 fwd->listen_host, fwd->listen_port, 529 (fwd->connect_path != NULL) ? fwd->connect_path : 530 fwd->connect_host, fwd->connect_port); 531 break; 532 case MUX_FWD_DYNAMIC: 533 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 534 (fwd->listen_host == NULL) ? 535 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 536 fwd->listen_host, fwd->listen_port); 537 break; 538 case MUX_FWD_REMOTE: 539 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 540 (fwd->listen_path != NULL) ? fwd->listen_path : 541 (fwd->listen_host == NULL) ? 542 "LOCALHOST" : fwd->listen_host, 543 fwd->listen_port, 544 (fwd->connect_path != NULL) ? fwd->connect_path : 545 fwd->connect_host, fwd->connect_port); 546 break; 547 default: 548 fatal("%s: unknown forward type %u", __func__, ftype); 549 } 550 return ret; 551} 552 553static int 554compare_host(const char *a, const char *b) 555{ 556 if (a == NULL && b == NULL) 557 return 1; 558 if (a == NULL || b == NULL) 559 return 0; 560 return strcmp(a, b) == 0; 561} 562 563static int 564compare_forward(struct Forward *a, struct Forward *b) 565{ 566 if (!compare_host(a->listen_host, b->listen_host)) 567 return 0; 568 if (!compare_host(a->listen_path, b->listen_path)) 569 return 0; 570 if (a->listen_port != b->listen_port) 571 return 0; 572 if (!compare_host(a->connect_host, b->connect_host)) 573 return 0; 574 if (!compare_host(a->connect_path, b->connect_path)) 575 return 0; 576 if (a->connect_port != b->connect_port) 577 return 0; 578 579 return 1; 580} 581 582static void 583mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 584{ 585 struct mux_channel_confirm_ctx *fctx = ctxt; 586 char *failmsg = NULL; 587 struct Forward *rfwd; 588 Channel *c; 589 Buffer out; 590 591 if ((c = channel_by_id(fctx->cid)) == NULL) { 592 /* no channel for reply */ 593 error("%s: unknown channel", __func__); 594 return; 595 } 596 buffer_init(&out); 597 if (fctx->fid >= options.num_remote_forwards || 598 (options.remote_forwards[fctx->fid].connect_path == NULL && 599 options.remote_forwards[fctx->fid].connect_host == NULL)) { 600 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 601 goto fail; 602 } 603 rfwd = &options.remote_forwards[fctx->fid]; 604 debug("%s: %s for: listen %d, connect %s:%d", __func__, 605 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 606 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 607 rfwd->connect_host, rfwd->connect_port); 608 if (type == SSH2_MSG_REQUEST_SUCCESS) { 609 if (rfwd->listen_port == 0) { 610 rfwd->allocated_port = packet_get_int(); 611 debug("Allocated port %u for mux remote forward" 612 " to %s:%d", rfwd->allocated_port, 613 rfwd->connect_host, rfwd->connect_port); 614 buffer_put_int(&out, MUX_S_REMOTE_PORT); 615 buffer_put_int(&out, fctx->rid); 616 buffer_put_int(&out, rfwd->allocated_port); 617 channel_update_permitted_opens(rfwd->handle, 618 rfwd->allocated_port); 619 } else { 620 buffer_put_int(&out, MUX_S_OK); 621 buffer_put_int(&out, fctx->rid); 622 } 623 goto out; 624 } else { 625 if (rfwd->listen_port == 0) 626 channel_update_permitted_opens(rfwd->handle, -1); 627 if (rfwd->listen_path != NULL) 628 xasprintf(&failmsg, "remote port forwarding failed for " 629 "listen path %s", rfwd->listen_path); 630 else 631 xasprintf(&failmsg, "remote port forwarding failed for " 632 "listen port %d", rfwd->listen_port); 633 634 debug2("%s: clearing registered forwarding for listen %d, " 635 "connect %s:%d", __func__, rfwd->listen_port, 636 rfwd->connect_path ? rfwd->connect_path : 637 rfwd->connect_host, rfwd->connect_port); 638 639 free(rfwd->listen_host); 640 free(rfwd->listen_path); 641 free(rfwd->connect_host); 642 free(rfwd->connect_path); 643 memset(rfwd, 0, sizeof(*rfwd)); 644 } 645 fail: 646 error("%s: %s", __func__, failmsg); 647 buffer_put_int(&out, MUX_S_FAILURE); 648 buffer_put_int(&out, fctx->rid); 649 buffer_put_cstring(&out, failmsg); 650 free(failmsg); 651 out: 652 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 653 buffer_free(&out); 654 if (c->mux_pause <= 0) 655 fatal("%s: mux_pause %d", __func__, c->mux_pause); 656 c->mux_pause = 0; /* start processing messages again */ 657} 658 659static int 660process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 661{ 662 struct Forward fwd; 663 char *fwd_desc = NULL; 664 char *listen_addr, *connect_addr; 665 u_int ftype; 666 u_int lport, cport; 667 int i, ret = 0, freefwd = 1; 668 669 memset(&fwd, 0, sizeof(fwd)); 670 671 /* XXX - lport/cport check redundant */ 672 if (buffer_get_int_ret(&ftype, m) != 0 || 673 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 674 buffer_get_int_ret(&lport, m) != 0 || 675 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 676 buffer_get_int_ret(&cport, m) != 0 || 677 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 678 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 679 error("%s: malformed message", __func__); 680 ret = -1; 681 goto out; 682 } 683 if (*listen_addr == '\0') { 684 free(listen_addr); 685 listen_addr = NULL; 686 } 687 if (*connect_addr == '\0') { 688 free(connect_addr); 689 connect_addr = NULL; 690 } 691 692 memset(&fwd, 0, sizeof(fwd)); 693 fwd.listen_port = lport; 694 if (fwd.listen_port == PORT_STREAMLOCAL) 695 fwd.listen_path = listen_addr; 696 else 697 fwd.listen_host = listen_addr; 698 fwd.connect_port = cport; 699 if (fwd.connect_port == PORT_STREAMLOCAL) 700 fwd.connect_path = connect_addr; 701 else 702 fwd.connect_host = connect_addr; 703 704 debug2("%s: channel %d: request %s", __func__, c->self, 705 (fwd_desc = format_forward(ftype, &fwd))); 706 707 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 708 ftype != MUX_FWD_DYNAMIC) { 709 logit("%s: invalid forwarding type %u", __func__, ftype); 710 invalid: 711 free(listen_addr); 712 free(connect_addr); 713 buffer_put_int(r, MUX_S_FAILURE); 714 buffer_put_int(r, rid); 715 buffer_put_cstring(r, "Invalid forwarding request"); 716 return 0; 717 } 718 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 719 logit("%s: streamlocal and dynamic forwards " 720 "are mutually exclusive", __func__); 721 goto invalid; 722 } 723 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 724 logit("%s: invalid listen port %u", __func__, 725 fwd.listen_port); 726 goto invalid; 727 } 728 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 729 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 730 logit("%s: invalid connect port %u", __func__, 731 fwd.connect_port); 732 goto invalid; 733 } 734 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 735 logit("%s: missing connect host", __func__); 736 goto invalid; 737 } 738 739 /* Skip forwards that have already been requested */ 740 switch (ftype) { 741 case MUX_FWD_LOCAL: 742 case MUX_FWD_DYNAMIC: 743 for (i = 0; i < options.num_local_forwards; i++) { 744 if (compare_forward(&fwd, 745 options.local_forwards + i)) { 746 exists: 747 debug2("%s: found existing forwarding", 748 __func__); 749 buffer_put_int(r, MUX_S_OK); 750 buffer_put_int(r, rid); 751 goto out; 752 } 753 } 754 break; 755 case MUX_FWD_REMOTE: 756 for (i = 0; i < options.num_remote_forwards; i++) { 757 if (compare_forward(&fwd, 758 options.remote_forwards + i)) { 759 if (fwd.listen_port != 0) 760 goto exists; 761 debug2("%s: found allocated port", 762 __func__); 763 buffer_put_int(r, MUX_S_REMOTE_PORT); 764 buffer_put_int(r, rid); 765 buffer_put_int(r, 766 options.remote_forwards[i].allocated_port); 767 goto out; 768 } 769 } 770 break; 771 } 772 773 if (options.control_master == SSHCTL_MASTER_ASK || 774 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 775 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 776 debug2("%s: forwarding refused by user", __func__); 777 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 778 buffer_put_int(r, rid); 779 buffer_put_cstring(r, "Permission denied"); 780 goto out; 781 } 782 } 783 784 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 785 if (!channel_setup_local_fwd_listener(&fwd, 786 &options.fwd_opts)) { 787 fail: 788 logit("slave-requested %s failed", fwd_desc); 789 buffer_put_int(r, MUX_S_FAILURE); 790 buffer_put_int(r, rid); 791 buffer_put_cstring(r, "Port forwarding failed"); 792 goto out; 793 } 794 add_local_forward(&options, &fwd); 795 freefwd = 0; 796 } else { 797 struct mux_channel_confirm_ctx *fctx; 798 799 fwd.handle = channel_request_remote_forwarding(&fwd); 800 if (fwd.handle < 0) 801 goto fail; 802 add_remote_forward(&options, &fwd); 803 fctx = xcalloc(1, sizeof(*fctx)); 804 fctx->cid = c->self; 805 fctx->rid = rid; 806 fctx->fid = options.num_remote_forwards - 1; 807 client_register_global_confirm(mux_confirm_remote_forward, 808 fctx); 809 freefwd = 0; 810 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 811 /* delayed reply in mux_confirm_remote_forward */ 812 goto out; 813 } 814 buffer_put_int(r, MUX_S_OK); 815 buffer_put_int(r, rid); 816 out: 817 free(fwd_desc); 818 if (freefwd) { 819 free(fwd.listen_host); 820 free(fwd.listen_path); 821 free(fwd.connect_host); 822 free(fwd.connect_path); 823 } 824 return ret; 825} 826 827static int 828process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 829{ 830 struct Forward fwd, *found_fwd; 831 char *fwd_desc = NULL; 832 const char *error_reason = NULL; 833 char *listen_addr = NULL, *connect_addr = NULL; 834 u_int ftype; 835 int i, ret = 0; 836 u_int lport, cport; 837 838 memset(&fwd, 0, sizeof(fwd)); 839 840 if (buffer_get_int_ret(&ftype, m) != 0 || 841 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 842 buffer_get_int_ret(&lport, m) != 0 || 843 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 844 buffer_get_int_ret(&cport, m) != 0 || 845 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 846 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 847 error("%s: malformed message", __func__); 848 ret = -1; 849 goto out; 850 } 851 852 if (*listen_addr == '\0') { 853 free(listen_addr); 854 listen_addr = NULL; 855 } 856 if (*connect_addr == '\0') { 857 free(connect_addr); 858 connect_addr = NULL; 859 } 860 861 memset(&fwd, 0, sizeof(fwd)); 862 fwd.listen_port = lport; 863 if (fwd.listen_port == PORT_STREAMLOCAL) 864 fwd.listen_path = listen_addr; 865 else 866 fwd.listen_host = listen_addr; 867 fwd.connect_port = cport; 868 if (fwd.connect_port == PORT_STREAMLOCAL) 869 fwd.connect_path = connect_addr; 870 else 871 fwd.connect_host = connect_addr; 872 873 debug2("%s: channel %d: request cancel %s", __func__, c->self, 874 (fwd_desc = format_forward(ftype, &fwd))); 875 876 /* make sure this has been requested */ 877 found_fwd = NULL; 878 switch (ftype) { 879 case MUX_FWD_LOCAL: 880 case MUX_FWD_DYNAMIC: 881 for (i = 0; i < options.num_local_forwards; i++) { 882 if (compare_forward(&fwd, 883 options.local_forwards + i)) { 884 found_fwd = options.local_forwards + i; 885 break; 886 } 887 } 888 break; 889 case MUX_FWD_REMOTE: 890 for (i = 0; i < options.num_remote_forwards; i++) { 891 if (compare_forward(&fwd, 892 options.remote_forwards + i)) { 893 found_fwd = options.remote_forwards + i; 894 break; 895 } 896 } 897 break; 898 } 899 900 if (found_fwd == NULL) 901 error_reason = "port not forwarded"; 902 else if (ftype == MUX_FWD_REMOTE) { 903 /* 904 * This shouldn't fail unless we confused the host/port 905 * between options.remote_forwards and permitted_opens. 906 * However, for dynamic allocated listen ports we need 907 * to use the actual listen port. 908 */ 909 if (channel_request_rforward_cancel(found_fwd) == -1) 910 error_reason = "port not in permitted opens"; 911 } else { /* local and dynamic forwards */ 912 /* Ditto */ 913 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 914 &options.fwd_opts) == -1) 915 error_reason = "port not found"; 916 } 917 918 if (error_reason == NULL) { 919 buffer_put_int(r, MUX_S_OK); 920 buffer_put_int(r, rid); 921 922 free(found_fwd->listen_host); 923 free(found_fwd->listen_path); 924 free(found_fwd->connect_host); 925 free(found_fwd->connect_path); 926 found_fwd->listen_host = found_fwd->connect_host = NULL; 927 found_fwd->listen_path = found_fwd->connect_path = NULL; 928 found_fwd->listen_port = found_fwd->connect_port = 0; 929 } else { 930 buffer_put_int(r, MUX_S_FAILURE); 931 buffer_put_int(r, rid); 932 buffer_put_cstring(r, error_reason); 933 } 934 out: 935 free(fwd_desc); 936 free(listen_addr); 937 free(connect_addr); 938 939 return ret; 940} 941 942static int 943process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 944{ 945 Channel *nc; 946 char *reserved, *chost; 947 u_int cport, i, j; 948 int new_fd[2]; 949 struct mux_stdio_confirm_ctx *cctx; 950 951 chost = reserved = NULL; 952 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 953 (chost = buffer_get_string_ret(m, NULL)) == NULL || 954 buffer_get_int_ret(&cport, m) != 0) { 955 free(reserved); 956 free(chost); 957 error("%s: malformed message", __func__); 958 return -1; 959 } 960 free(reserved); 961 962 debug2("%s: channel %d: request stdio fwd to %s:%u", 963 __func__, c->self, chost, cport); 964 965 /* Gather fds from client */ 966 for(i = 0; i < 2; i++) { 967 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 968 error("%s: failed to receive fd %d from slave", 969 __func__, i); 970 for (j = 0; j < i; j++) 971 close(new_fd[j]); 972 free(chost); 973 974 /* prepare reply */ 975 buffer_put_int(r, MUX_S_FAILURE); 976 buffer_put_int(r, rid); 977 buffer_put_cstring(r, 978 "did not receive file descriptors"); 979 return -1; 980 } 981 } 982 983 debug3("%s: got fds stdin %d, stdout %d", __func__, 984 new_fd[0], new_fd[1]); 985 986 /* XXX support multiple child sessions in future */ 987 if (c->remote_id != -1) { 988 debug2("%s: session already open", __func__); 989 /* prepare reply */ 990 buffer_put_int(r, MUX_S_FAILURE); 991 buffer_put_int(r, rid); 992 buffer_put_cstring(r, "Multiple sessions not supported"); 993 cleanup: 994 close(new_fd[0]); 995 close(new_fd[1]); 996 free(chost); 997 return 0; 998 } 999 1000 if (options.control_master == SSHCTL_MASTER_ASK || 1001 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1002 if (!ask_permission("Allow forward to %s:%u? ", 1003 chost, cport)) { 1004 debug2("%s: stdio fwd refused by user", __func__); 1005 /* prepare reply */ 1006 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1007 buffer_put_int(r, rid); 1008 buffer_put_cstring(r, "Permission denied"); 1009 goto cleanup; 1010 } 1011 } 1012 1013 /* enable nonblocking unless tty */ 1014 if (!isatty(new_fd[0])) 1015 set_nonblock(new_fd[0]); 1016 if (!isatty(new_fd[1])) 1017 set_nonblock(new_fd[1]); 1018 1019 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1020 1021 nc->ctl_chan = c->self; /* link session -> control channel */ 1022 c->remote_id = nc->self; /* link control -> session channel */ 1023 1024 debug2("%s: channel_new: %d linked to control channel %d", 1025 __func__, nc->self, nc->ctl_chan); 1026 1027 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1028 1029 cctx = xcalloc(1, sizeof(*cctx)); 1030 cctx->rid = rid; 1031 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1032 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1033 1034 /* reply is deferred, sent by mux_session_confirm */ 1035 return 0; 1036} 1037 1038/* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1039static void 1040mux_stdio_confirm(int id, int success, void *arg) 1041{ 1042 struct mux_stdio_confirm_ctx *cctx = arg; 1043 Channel *c, *cc; 1044 Buffer reply; 1045 1046 if (cctx == NULL) 1047 fatal("%s: cctx == NULL", __func__); 1048 if ((c = channel_by_id(id)) == NULL) 1049 fatal("%s: no channel for id %d", __func__, id); 1050 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1051 fatal("%s: channel %d lacks control channel %d", __func__, 1052 id, c->ctl_chan); 1053 1054 if (!success) { 1055 debug3("%s: sending failure reply", __func__); 1056 /* prepare reply */ 1057 buffer_init(&reply); 1058 buffer_put_int(&reply, MUX_S_FAILURE); 1059 buffer_put_int(&reply, cctx->rid); 1060 buffer_put_cstring(&reply, "Session open refused by peer"); 1061 goto done; 1062 } 1063 1064 debug3("%s: sending success reply", __func__); 1065 /* prepare reply */ 1066 buffer_init(&reply); 1067 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1068 buffer_put_int(&reply, cctx->rid); 1069 buffer_put_int(&reply, c->self); 1070 1071 done: 1072 /* Send reply */ 1073 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1074 buffer_free(&reply); 1075 1076 if (cc->mux_pause <= 0) 1077 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1078 cc->mux_pause = 0; /* start processing messages again */ 1079 c->open_confirm_ctx = NULL; 1080 free(cctx); 1081} 1082 1083static int 1084process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1085{ 1086 debug("%s: channel %d: stop listening", __func__, c->self); 1087 1088 if (options.control_master == SSHCTL_MASTER_ASK || 1089 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1090 if (!ask_permission("Disable further multiplexing on shared " 1091 "connection to %s? ", host)) { 1092 debug2("%s: stop listen refused by user", __func__); 1093 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1094 buffer_put_int(r, rid); 1095 buffer_put_cstring(r, "Permission denied"); 1096 return 0; 1097 } 1098 } 1099 1100 if (mux_listener_channel != NULL) { 1101 channel_free(mux_listener_channel); 1102 client_stop_mux(); 1103 free(options.control_path); 1104 options.control_path = NULL; 1105 mux_listener_channel = NULL; 1106 muxserver_sock = -1; 1107 } 1108 1109 /* prepare reply */ 1110 buffer_put_int(r, MUX_S_OK); 1111 buffer_put_int(r, rid); 1112 1113 return 0; 1114} 1115 1116/* Channel callbacks fired on read/write from mux slave fd */ 1117static int 1118mux_master_read_cb(Channel *c) 1119{ 1120 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1121 Buffer in, out; 1122 const u_char *ptr; 1123 u_int type, rid, have, i; 1124 int ret = -1; 1125 1126 /* Setup ctx and */ 1127 if (c->mux_ctx == NULL) { 1128 state = xcalloc(1, sizeof(*state)); 1129 c->mux_ctx = state; 1130 channel_register_cleanup(c->self, 1131 mux_master_control_cleanup_cb, 0); 1132 1133 /* Send hello */ 1134 buffer_init(&out); 1135 buffer_put_int(&out, MUX_MSG_HELLO); 1136 buffer_put_int(&out, SSHMUX_VER); 1137 /* no extensions */ 1138 buffer_put_string(&c->output, buffer_ptr(&out), 1139 buffer_len(&out)); 1140 buffer_free(&out); 1141 debug3("%s: channel %d: hello sent", __func__, c->self); 1142 return 0; 1143 } 1144 1145 buffer_init(&in); 1146 buffer_init(&out); 1147 1148 /* Channel code ensures that we receive whole packets */ 1149 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1150 malf: 1151 error("%s: malformed message", __func__); 1152 goto out; 1153 } 1154 buffer_append(&in, ptr, have); 1155 1156 if (buffer_get_int_ret(&type, &in) != 0) 1157 goto malf; 1158 debug3("%s: channel %d packet type 0x%08x len %u", 1159 __func__, c->self, type, buffer_len(&in)); 1160 1161 if (type == MUX_MSG_HELLO) 1162 rid = 0; 1163 else { 1164 if (!state->hello_rcvd) { 1165 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1166 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1167 goto out; 1168 } 1169 if (buffer_get_int_ret(&rid, &in) != 0) 1170 goto malf; 1171 } 1172 1173 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1174 if (type == mux_master_handlers[i].type) { 1175 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1176 break; 1177 } 1178 } 1179 if (mux_master_handlers[i].handler == NULL) { 1180 error("%s: unsupported mux message 0x%08x", __func__, type); 1181 buffer_put_int(&out, MUX_S_FAILURE); 1182 buffer_put_int(&out, rid); 1183 buffer_put_cstring(&out, "unsupported request"); 1184 ret = 0; 1185 } 1186 /* Enqueue reply packet */ 1187 if (buffer_len(&out) != 0) { 1188 buffer_put_string(&c->output, buffer_ptr(&out), 1189 buffer_len(&out)); 1190 } 1191 out: 1192 buffer_free(&in); 1193 buffer_free(&out); 1194 return ret; 1195} 1196 1197void 1198mux_exit_message(Channel *c, int exitval) 1199{ 1200 Buffer m; 1201 Channel *mux_chan; 1202 1203 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1204 exitval); 1205 1206 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1207 fatal("%s: channel %d missing mux channel %d", 1208 __func__, c->self, c->ctl_chan); 1209 1210 /* Append exit message packet to control socket output queue */ 1211 buffer_init(&m); 1212 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1213 buffer_put_int(&m, c->self); 1214 buffer_put_int(&m, exitval); 1215 1216 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1217 buffer_free(&m); 1218} 1219 1220void 1221mux_tty_alloc_failed(Channel *c) 1222{ 1223 Buffer m; 1224 Channel *mux_chan; 1225 1226 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1227 1228 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1229 fatal("%s: channel %d missing mux channel %d", 1230 __func__, c->self, c->ctl_chan); 1231 1232 /* Append exit message packet to control socket output queue */ 1233 buffer_init(&m); 1234 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1235 buffer_put_int(&m, c->self); 1236 1237 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1238 buffer_free(&m); 1239} 1240 1241/* Prepare a mux master to listen on a Unix domain socket. */ 1242void 1243muxserver_listen(void) 1244{ 1245 mode_t old_umask; 1246 char *orig_control_path = options.control_path; 1247 char rbuf[16+1]; 1248 u_int i, r; 1249 int oerrno; 1250 1251 if (options.control_path == NULL || 1252 options.control_master == SSHCTL_MASTER_NO) 1253 return; 1254 1255 debug("setting up multiplex master socket"); 1256 1257 /* 1258 * Use a temporary path before listen so we can pseudo-atomically 1259 * establish the listening socket in its final location to avoid 1260 * other processes racing in between bind() and listen() and hitting 1261 * an unready socket. 1262 */ 1263 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1264 r = arc4random_uniform(26+26+10); 1265 rbuf[i] = (r < 26) ? 'a' + r : 1266 (r < 26*2) ? 'A' + r - 26 : 1267 '0' + r - 26 - 26; 1268 } 1269 rbuf[sizeof(rbuf) - 1] = '\0'; 1270 options.control_path = NULL; 1271 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1272 debug3("%s: temporary control path %s", __func__, options.control_path); 1273 1274 old_umask = umask(0177); 1275 muxserver_sock = unix_listener(options.control_path, 64, 0); 1276 oerrno = errno; 1277 umask(old_umask); 1278 if (muxserver_sock < 0) { 1279 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1280 error("ControlSocket %s already exists, " 1281 "disabling multiplexing", options.control_path); 1282 disable_mux_master: 1283 if (muxserver_sock != -1) { 1284 close(muxserver_sock); 1285 muxserver_sock = -1; 1286 } 1287 free(orig_control_path); 1288 free(options.control_path); 1289 options.control_path = NULL; 1290 options.control_master = SSHCTL_MASTER_NO; 1291 return; 1292 } else { 1293 /* unix_listener() logs the error */ 1294 cleanup_exit(255); 1295 } 1296 } 1297 1298 /* Now atomically "move" the mux socket into position */ 1299 if (link(options.control_path, orig_control_path) != 0) { 1300 if (errno != EEXIST) { 1301 fatal("%s: link mux listener %s => %s: %s", __func__, 1302 options.control_path, orig_control_path, 1303 strerror(errno)); 1304 } 1305 error("ControlSocket %s already exists, disabling multiplexing", 1306 orig_control_path); 1307 unlink(options.control_path); 1308 goto disable_mux_master; 1309 } 1310 unlink(options.control_path); 1311 free(options.control_path); 1312 options.control_path = orig_control_path; 1313 1314 set_nonblock(muxserver_sock); 1315 1316 mux_listener_channel = channel_new("mux listener", 1317 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1318 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1319 0, options.control_path, 1); 1320 mux_listener_channel->mux_rcb = mux_master_read_cb; 1321 debug3("%s: mux listener channel %d fd %d", __func__, 1322 mux_listener_channel->self, mux_listener_channel->sock); 1323} 1324 1325/* Callback on open confirmation in mux master for a mux client session. */ 1326static void 1327mux_session_confirm(int id, int success, void *arg) 1328{ 1329 struct mux_session_confirm_ctx *cctx = arg; 1330 const char *display; 1331 Channel *c, *cc; 1332 int i; 1333 Buffer reply; 1334 1335 if (cctx == NULL) 1336 fatal("%s: cctx == NULL", __func__); 1337 if ((c = channel_by_id(id)) == NULL) 1338 fatal("%s: no channel for id %d", __func__, id); 1339 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1340 fatal("%s: channel %d lacks control channel %d", __func__, 1341 id, c->ctl_chan); 1342 1343 if (!success) { 1344 debug3("%s: sending failure reply", __func__); 1345 /* prepare reply */ 1346 buffer_init(&reply); 1347 buffer_put_int(&reply, MUX_S_FAILURE); 1348 buffer_put_int(&reply, cctx->rid); 1349 buffer_put_cstring(&reply, "Session open refused by peer"); 1350 goto done; 1351 } 1352 1353 display = getenv("DISPLAY"); 1354 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1355 char *proto, *data; 1356 1357 /* Get reasonable local authentication information. */ 1358 client_x11_get_proto(display, options.xauth_location, 1359 options.forward_x11_trusted, options.forward_x11_timeout, 1360 &proto, &data); 1361 /* Request forwarding with authentication spoofing. */ 1362 debug("Requesting X11 forwarding with authentication " 1363 "spoofing."); 1364 x11_request_forwarding_with_spoofing(id, display, proto, 1365 data, 1); 1366 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1367 /* XXX exit_on_forward_failure */ 1368 } 1369 1370 if (cctx->want_agent_fwd && options.forward_agent) { 1371 debug("Requesting authentication agent forwarding."); 1372 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1373 packet_send(); 1374 } 1375 1376 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1377 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1378 1379 debug3("%s: sending success reply", __func__); 1380 /* prepare reply */ 1381 buffer_init(&reply); 1382 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1383 buffer_put_int(&reply, cctx->rid); 1384 buffer_put_int(&reply, c->self); 1385 1386 done: 1387 /* Send reply */ 1388 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1389 buffer_free(&reply); 1390 1391 if (cc->mux_pause <= 0) 1392 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1393 cc->mux_pause = 0; /* start processing messages again */ 1394 c->open_confirm_ctx = NULL; 1395 buffer_free(&cctx->cmd); 1396 free(cctx->term); 1397 if (cctx->env != NULL) { 1398 for (i = 0; cctx->env[i] != NULL; i++) 1399 free(cctx->env[i]); 1400 free(cctx->env); 1401 } 1402 free(cctx); 1403} 1404 1405/* ** Multiplexing client support */ 1406 1407/* Exit signal handler */ 1408static void 1409control_client_sighandler(int signo) 1410{ 1411 muxclient_terminate = signo; 1412} 1413 1414/* 1415 * Relay signal handler - used to pass some signals from mux client to 1416 * mux master. 1417 */ 1418static void 1419control_client_sigrelay(int signo) 1420{ 1421 int save_errno = errno; 1422 1423 if (muxserver_pid > 1) 1424 kill(muxserver_pid, signo); 1425 1426 errno = save_errno; 1427} 1428 1429static int 1430mux_client_read(int fd, Buffer *b, u_int need) 1431{ 1432 u_int have; 1433 ssize_t len; 1434 u_char *p; 1435 struct pollfd pfd; 1436 1437 pfd.fd = fd; 1438 pfd.events = POLLIN; 1439 p = buffer_append_space(b, need); 1440 for (have = 0; have < need; ) { 1441 if (muxclient_terminate) { 1442 errno = EINTR; 1443 return -1; 1444 } 1445 len = read(fd, p + have, need - have); 1446 if (len < 0) { 1447 switch (errno) { 1448#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1449 case EWOULDBLOCK: 1450#endif 1451 case EAGAIN: 1452 (void)poll(&pfd, 1, -1); 1453 /* FALLTHROUGH */ 1454 case EINTR: 1455 continue; 1456 default: 1457 return -1; 1458 } 1459 } 1460 if (len == 0) { 1461 errno = EPIPE; 1462 return -1; 1463 } 1464 have += (u_int)len; 1465 } 1466 return 0; 1467} 1468 1469static int 1470mux_client_write_packet(int fd, Buffer *m) 1471{ 1472 Buffer queue; 1473 u_int have, need; 1474 int oerrno, len; 1475 u_char *ptr; 1476 struct pollfd pfd; 1477 1478 pfd.fd = fd; 1479 pfd.events = POLLOUT; 1480 buffer_init(&queue); 1481 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1482 1483 need = buffer_len(&queue); 1484 ptr = buffer_ptr(&queue); 1485 1486 for (have = 0; have < need; ) { 1487 if (muxclient_terminate) { 1488 buffer_free(&queue); 1489 errno = EINTR; 1490 return -1; 1491 } 1492 len = write(fd, ptr + have, need - have); 1493 if (len < 0) { 1494 switch (errno) { 1495#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1496 case EWOULDBLOCK: 1497#endif 1498 case EAGAIN: 1499 (void)poll(&pfd, 1, -1); 1500 /* FALLTHROUGH */ 1501 case EINTR: 1502 continue; 1503 default: 1504 oerrno = errno; 1505 buffer_free(&queue); 1506 errno = oerrno; 1507 return -1; 1508 } 1509 } 1510 if (len == 0) { 1511 buffer_free(&queue); 1512 errno = EPIPE; 1513 return -1; 1514 } 1515 have += (u_int)len; 1516 } 1517 buffer_free(&queue); 1518 return 0; 1519} 1520 1521static int 1522mux_client_read_packet(int fd, Buffer *m) 1523{ 1524 Buffer queue; 1525 u_int need, have; 1526 const u_char *ptr; 1527 int oerrno; 1528 1529 buffer_init(&queue); 1530 if (mux_client_read(fd, &queue, 4) != 0) { 1531 if ((oerrno = errno) == EPIPE) 1532 debug3("%s: read header failed: %s", __func__, 1533 strerror(errno)); 1534 buffer_free(&queue); 1535 errno = oerrno; 1536 return -1; 1537 } 1538 need = get_u32(buffer_ptr(&queue)); 1539 if (mux_client_read(fd, &queue, need) != 0) { 1540 oerrno = errno; 1541 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1542 buffer_free(&queue); 1543 errno = oerrno; 1544 return -1; 1545 } 1546 ptr = buffer_get_string_ptr(&queue, &have); 1547 buffer_append(m, ptr, have); 1548 buffer_free(&queue); 1549 return 0; 1550} 1551 1552static int 1553mux_client_hello_exchange(int fd) 1554{ 1555 Buffer m; 1556 u_int type, ver; 1557 1558 buffer_init(&m); 1559 buffer_put_int(&m, MUX_MSG_HELLO); 1560 buffer_put_int(&m, SSHMUX_VER); 1561 /* no extensions */ 1562 1563 if (mux_client_write_packet(fd, &m) != 0) 1564 fatal("%s: write packet: %s", __func__, strerror(errno)); 1565 1566 buffer_clear(&m); 1567 1568 /* Read their HELLO */ 1569 if (mux_client_read_packet(fd, &m) != 0) { 1570 buffer_free(&m); 1571 return -1; 1572 } 1573 1574 type = buffer_get_int(&m); 1575 if (type != MUX_MSG_HELLO) 1576 fatal("%s: expected HELLO (%u) received %u", 1577 __func__, MUX_MSG_HELLO, type); 1578 ver = buffer_get_int(&m); 1579 if (ver != SSHMUX_VER) 1580 fatal("Unsupported multiplexing protocol version %d " 1581 "(expected %d)", ver, SSHMUX_VER); 1582 debug2("%s: master version %u", __func__, ver); 1583 /* No extensions are presently defined */ 1584 while (buffer_len(&m) > 0) { 1585 char *name = buffer_get_string(&m, NULL); 1586 char *value = buffer_get_string(&m, NULL); 1587 1588 debug2("Unrecognised master extension \"%s\"", name); 1589 free(name); 1590 free(value); 1591 } 1592 buffer_free(&m); 1593 return 0; 1594} 1595 1596static u_int 1597mux_client_request_alive(int fd) 1598{ 1599 Buffer m; 1600 char *e; 1601 u_int pid, type, rid; 1602 1603 debug3("%s: entering", __func__); 1604 1605 buffer_init(&m); 1606 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1607 buffer_put_int(&m, muxclient_request_id); 1608 1609 if (mux_client_write_packet(fd, &m) != 0) 1610 fatal("%s: write packet: %s", __func__, strerror(errno)); 1611 1612 buffer_clear(&m); 1613 1614 /* Read their reply */ 1615 if (mux_client_read_packet(fd, &m) != 0) { 1616 buffer_free(&m); 1617 return 0; 1618 } 1619 1620 type = buffer_get_int(&m); 1621 if (type != MUX_S_ALIVE) { 1622 e = buffer_get_string(&m, NULL); 1623 fatal("%s: master returned error: %s", __func__, e); 1624 } 1625 1626 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1627 fatal("%s: out of sequence reply: my id %u theirs %u", 1628 __func__, muxclient_request_id, rid); 1629 pid = buffer_get_int(&m); 1630 buffer_free(&m); 1631 1632 debug3("%s: done pid = %u", __func__, pid); 1633 1634 muxclient_request_id++; 1635 1636 return pid; 1637} 1638 1639static void 1640mux_client_request_terminate(int fd) 1641{ 1642 Buffer m; 1643 char *e; 1644 u_int type, rid; 1645 1646 debug3("%s: entering", __func__); 1647 1648 buffer_init(&m); 1649 buffer_put_int(&m, MUX_C_TERMINATE); 1650 buffer_put_int(&m, muxclient_request_id); 1651 1652 if (mux_client_write_packet(fd, &m) != 0) 1653 fatal("%s: write packet: %s", __func__, strerror(errno)); 1654 1655 buffer_clear(&m); 1656 1657 /* Read their reply */ 1658 if (mux_client_read_packet(fd, &m) != 0) { 1659 /* Remote end exited already */ 1660 if (errno == EPIPE) { 1661 buffer_free(&m); 1662 return; 1663 } 1664 fatal("%s: read from master failed: %s", 1665 __func__, strerror(errno)); 1666 } 1667 1668 type = buffer_get_int(&m); 1669 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1670 fatal("%s: out of sequence reply: my id %u theirs %u", 1671 __func__, muxclient_request_id, rid); 1672 switch (type) { 1673 case MUX_S_OK: 1674 break; 1675 case MUX_S_PERMISSION_DENIED: 1676 e = buffer_get_string(&m, NULL); 1677 fatal("Master refused termination request: %s", e); 1678 case MUX_S_FAILURE: 1679 e = buffer_get_string(&m, NULL); 1680 fatal("%s: termination request failed: %s", __func__, e); 1681 default: 1682 fatal("%s: unexpected response from master 0x%08x", 1683 __func__, type); 1684 } 1685 buffer_free(&m); 1686 muxclient_request_id++; 1687} 1688 1689static int 1690mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1691{ 1692 Buffer m; 1693 char *e, *fwd_desc; 1694 u_int type, rid; 1695 1696 fwd_desc = format_forward(ftype, fwd); 1697 debug("Requesting %s %s", 1698 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1699 free(fwd_desc); 1700 1701 buffer_init(&m); 1702 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1703 buffer_put_int(&m, muxclient_request_id); 1704 buffer_put_int(&m, ftype); 1705 if (fwd->listen_path != NULL) { 1706 buffer_put_cstring(&m, fwd->listen_path); 1707 } else { 1708 buffer_put_cstring(&m, 1709 fwd->listen_host == NULL ? "" : 1710 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1711 } 1712 buffer_put_int(&m, fwd->listen_port); 1713 if (fwd->connect_path != NULL) { 1714 buffer_put_cstring(&m, fwd->connect_path); 1715 } else { 1716 buffer_put_cstring(&m, 1717 fwd->connect_host == NULL ? "" : fwd->connect_host); 1718 } 1719 buffer_put_int(&m, fwd->connect_port); 1720 1721 if (mux_client_write_packet(fd, &m) != 0) 1722 fatal("%s: write packet: %s", __func__, strerror(errno)); 1723 1724 buffer_clear(&m); 1725 1726 /* Read their reply */ 1727 if (mux_client_read_packet(fd, &m) != 0) { 1728 buffer_free(&m); 1729 return -1; 1730 } 1731 1732 type = buffer_get_int(&m); 1733 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1734 fatal("%s: out of sequence reply: my id %u theirs %u", 1735 __func__, muxclient_request_id, rid); 1736 switch (type) { 1737 case MUX_S_OK: 1738 break; 1739 case MUX_S_REMOTE_PORT: 1740 if (cancel_flag) 1741 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1742 fwd->allocated_port = buffer_get_int(&m); 1743 verbose("Allocated port %u for remote forward to %s:%d", 1744 fwd->allocated_port, 1745 fwd->connect_host ? fwd->connect_host : "", 1746 fwd->connect_port); 1747 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1748 fprintf(stdout, "%u\n", fwd->allocated_port); 1749 break; 1750 case MUX_S_PERMISSION_DENIED: 1751 e = buffer_get_string(&m, NULL); 1752 buffer_free(&m); 1753 error("Master refused forwarding request: %s", e); 1754 return -1; 1755 case MUX_S_FAILURE: 1756 e = buffer_get_string(&m, NULL); 1757 buffer_free(&m); 1758 error("%s: forwarding request failed: %s", __func__, e); 1759 return -1; 1760 default: 1761 fatal("%s: unexpected response from master 0x%08x", 1762 __func__, type); 1763 } 1764 buffer_free(&m); 1765 1766 muxclient_request_id++; 1767 return 0; 1768} 1769 1770static int 1771mux_client_forwards(int fd, int cancel_flag) 1772{ 1773 int i, ret = 0; 1774 1775 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1776 cancel_flag ? "cancel" : "request", 1777 options.num_local_forwards, options.num_remote_forwards); 1778 1779 /* XXX ExitOnForwardingFailure */ 1780 for (i = 0; i < options.num_local_forwards; i++) { 1781 if (mux_client_forward(fd, cancel_flag, 1782 options.local_forwards[i].connect_port == 0 ? 1783 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1784 options.local_forwards + i) != 0) 1785 ret = -1; 1786 } 1787 for (i = 0; i < options.num_remote_forwards; i++) { 1788 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1789 options.remote_forwards + i) != 0) 1790 ret = -1; 1791 } 1792 return ret; 1793} 1794 1795static int 1796mux_client_request_session(int fd) 1797{ 1798 Buffer m; 1799 char *e, *term; 1800 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1801 extern char **environ; 1802 int devnull, rawmode; 1803 1804 debug3("%s: entering", __func__); 1805 1806 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1807 error("%s: master alive request failed", __func__); 1808 return -1; 1809 } 1810 1811 signal(SIGPIPE, SIG_IGN); 1812 1813 if (stdin_null_flag) { 1814 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1815 fatal("open(/dev/null): %s", strerror(errno)); 1816 if (dup2(devnull, STDIN_FILENO) == -1) 1817 fatal("dup2: %s", strerror(errno)); 1818 if (devnull > STDERR_FILENO) 1819 close(devnull); 1820 } 1821 1822 term = getenv("TERM"); 1823 1824 buffer_init(&m); 1825 buffer_put_int(&m, MUX_C_NEW_SESSION); 1826 buffer_put_int(&m, muxclient_request_id); 1827 buffer_put_cstring(&m, ""); /* reserved */ 1828 buffer_put_int(&m, tty_flag); 1829 buffer_put_int(&m, options.forward_x11); 1830 buffer_put_int(&m, options.forward_agent); 1831 buffer_put_int(&m, subsystem_flag); 1832 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1833 0xffffffff : (u_int)options.escape_char); 1834 buffer_put_cstring(&m, term == NULL ? "" : term); 1835 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1836 1837 if (options.num_send_env > 0 && environ != NULL) { 1838 /* Pass environment */ 1839 for (i = 0; environ[i] != NULL; i++) { 1840 if (env_permitted(environ[i])) { 1841 buffer_put_cstring(&m, environ[i]); 1842 } 1843 } 1844 } 1845 1846 if (mux_client_write_packet(fd, &m) != 0) 1847 fatal("%s: write packet: %s", __func__, strerror(errno)); 1848 1849 /* Send the stdio file descriptors */ 1850 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1851 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1852 mm_send_fd(fd, STDERR_FILENO) == -1) 1853 fatal("%s: send fds failed", __func__); 1854 1855 debug3("%s: session request sent", __func__); 1856 1857 /* Read their reply */ 1858 buffer_clear(&m); 1859 if (mux_client_read_packet(fd, &m) != 0) { 1860 error("%s: read from master failed: %s", 1861 __func__, strerror(errno)); 1862 buffer_free(&m); 1863 return -1; 1864 } 1865 1866 type = buffer_get_int(&m); 1867 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1868 fatal("%s: out of sequence reply: my id %u theirs %u", 1869 __func__, muxclient_request_id, rid); 1870 switch (type) { 1871 case MUX_S_SESSION_OPENED: 1872 sid = buffer_get_int(&m); 1873 debug("%s: master session id: %u", __func__, sid); 1874 break; 1875 case MUX_S_PERMISSION_DENIED: 1876 e = buffer_get_string(&m, NULL); 1877 buffer_free(&m); 1878 error("Master refused session request: %s", e); 1879 return -1; 1880 case MUX_S_FAILURE: 1881 e = buffer_get_string(&m, NULL); 1882 buffer_free(&m); 1883 error("%s: session request failed: %s", __func__, e); 1884 return -1; 1885 default: 1886 buffer_free(&m); 1887 error("%s: unexpected response from master 0x%08x", 1888 __func__, type); 1889 return -1; 1890 } 1891 muxclient_request_id++; 1892 1893 signal(SIGHUP, control_client_sighandler); 1894 signal(SIGINT, control_client_sighandler); 1895 signal(SIGTERM, control_client_sighandler); 1896 signal(SIGWINCH, control_client_sigrelay); 1897 1898 rawmode = tty_flag; 1899 if (tty_flag) 1900 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1901 1902 /* 1903 * Stick around until the controlee closes the client_fd. 1904 * Before it does, it is expected to write an exit message. 1905 * This process must read the value and wait for the closure of 1906 * the client_fd; if this one closes early, the multiplex master will 1907 * terminate early too (possibly losing data). 1908 */ 1909 for (exitval = 255, exitval_seen = 0;;) { 1910 buffer_clear(&m); 1911 if (mux_client_read_packet(fd, &m) != 0) 1912 break; 1913 type = buffer_get_int(&m); 1914 switch (type) { 1915 case MUX_S_TTY_ALLOC_FAIL: 1916 if ((esid = buffer_get_int(&m)) != sid) 1917 fatal("%s: tty alloc fail on unknown session: " 1918 "my id %u theirs %u", 1919 __func__, sid, esid); 1920 leave_raw_mode(options.request_tty == 1921 REQUEST_TTY_FORCE); 1922 rawmode = 0; 1923 continue; 1924 case MUX_S_EXIT_MESSAGE: 1925 if ((esid = buffer_get_int(&m)) != sid) 1926 fatal("%s: exit on unknown session: " 1927 "my id %u theirs %u", 1928 __func__, sid, esid); 1929 if (exitval_seen) 1930 fatal("%s: exitval sent twice", __func__); 1931 exitval = buffer_get_int(&m); 1932 exitval_seen = 1; 1933 continue; 1934 default: 1935 e = buffer_get_string(&m, NULL); 1936 fatal("%s: master returned error: %s", __func__, e); 1937 } 1938 } 1939 1940 close(fd); 1941 if (rawmode) 1942 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1943 1944 if (muxclient_terminate) { 1945 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1946 exitval = 255; 1947 } else if (!exitval_seen) { 1948 debug2("Control master terminated unexpectedly"); 1949 exitval = 255; 1950 } else 1951 debug2("Received exit status from master %d", exitval); 1952 1953 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1954 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1955 1956 exit(exitval); 1957} 1958 1959static int 1960mux_client_request_stdio_fwd(int fd) 1961{ 1962 Buffer m; 1963 char *e; 1964 u_int type, rid, sid; 1965 int devnull; 1966 1967 debug3("%s: entering", __func__); 1968 1969 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1970 error("%s: master alive request failed", __func__); 1971 return -1; 1972 } 1973 1974 signal(SIGPIPE, SIG_IGN); 1975 1976 if (stdin_null_flag) { 1977 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1978 fatal("open(/dev/null): %s", strerror(errno)); 1979 if (dup2(devnull, STDIN_FILENO) == -1) 1980 fatal("dup2: %s", strerror(errno)); 1981 if (devnull > STDERR_FILENO) 1982 close(devnull); 1983 } 1984 1985 buffer_init(&m); 1986 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1987 buffer_put_int(&m, muxclient_request_id); 1988 buffer_put_cstring(&m, ""); /* reserved */ 1989 buffer_put_cstring(&m, stdio_forward_host); 1990 buffer_put_int(&m, stdio_forward_port); 1991 1992 if (mux_client_write_packet(fd, &m) != 0) 1993 fatal("%s: write packet: %s", __func__, strerror(errno)); 1994 1995 /* Send the stdio file descriptors */ 1996 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1997 mm_send_fd(fd, STDOUT_FILENO) == -1) 1998 fatal("%s: send fds failed", __func__); 1999 2000 debug3("%s: stdio forward request sent", __func__); 2001 2002 /* Read their reply */ 2003 buffer_clear(&m); 2004 2005 if (mux_client_read_packet(fd, &m) != 0) { 2006 error("%s: read from master failed: %s", 2007 __func__, strerror(errno)); 2008 buffer_free(&m); 2009 return -1; 2010 } 2011 2012 type = buffer_get_int(&m); 2013 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2014 fatal("%s: out of sequence reply: my id %u theirs %u", 2015 __func__, muxclient_request_id, rid); 2016 switch (type) { 2017 case MUX_S_SESSION_OPENED: 2018 sid = buffer_get_int(&m); 2019 debug("%s: master session id: %u", __func__, sid); 2020 break; 2021 case MUX_S_PERMISSION_DENIED: 2022 e = buffer_get_string(&m, NULL); 2023 buffer_free(&m); 2024 fatal("Master refused stdio forwarding request: %s", e); 2025 case MUX_S_FAILURE: 2026 e = buffer_get_string(&m, NULL); 2027 buffer_free(&m); 2028 fatal("Stdio forwarding request failed: %s", e); 2029 default: 2030 buffer_free(&m); 2031 error("%s: unexpected response from master 0x%08x", 2032 __func__, type); 2033 return -1; 2034 } 2035 muxclient_request_id++; 2036 2037 signal(SIGHUP, control_client_sighandler); 2038 signal(SIGINT, control_client_sighandler); 2039 signal(SIGTERM, control_client_sighandler); 2040 signal(SIGWINCH, control_client_sigrelay); 2041 2042 /* 2043 * Stick around until the controlee closes the client_fd. 2044 */ 2045 buffer_clear(&m); 2046 if (mux_client_read_packet(fd, &m) != 0) { 2047 if (errno == EPIPE || 2048 (errno == EINTR && muxclient_terminate != 0)) 2049 return 0; 2050 fatal("%s: mux_client_read_packet: %s", 2051 __func__, strerror(errno)); 2052 } 2053 fatal("%s: master returned unexpected message %u", __func__, type); 2054} 2055 2056static void 2057mux_client_request_stop_listening(int fd) 2058{ 2059 Buffer m; 2060 char *e; 2061 u_int type, rid; 2062 2063 debug3("%s: entering", __func__); 2064 2065 buffer_init(&m); 2066 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2067 buffer_put_int(&m, muxclient_request_id); 2068 2069 if (mux_client_write_packet(fd, &m) != 0) 2070 fatal("%s: write packet: %s", __func__, strerror(errno)); 2071 2072 buffer_clear(&m); 2073 2074 /* Read their reply */ 2075 if (mux_client_read_packet(fd, &m) != 0) 2076 fatal("%s: read from master failed: %s", 2077 __func__, strerror(errno)); 2078 2079 type = buffer_get_int(&m); 2080 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2081 fatal("%s: out of sequence reply: my id %u theirs %u", 2082 __func__, muxclient_request_id, rid); 2083 switch (type) { 2084 case MUX_S_OK: 2085 break; 2086 case MUX_S_PERMISSION_DENIED: 2087 e = buffer_get_string(&m, NULL); 2088 fatal("Master refused stop listening request: %s", e); 2089 case MUX_S_FAILURE: 2090 e = buffer_get_string(&m, NULL); 2091 fatal("%s: stop listening request failed: %s", __func__, e); 2092 default: 2093 fatal("%s: unexpected response from master 0x%08x", 2094 __func__, type); 2095 } 2096 buffer_free(&m); 2097 muxclient_request_id++; 2098} 2099 2100/* Multiplex client main loop. */ 2101void 2102muxclient(const char *path) 2103{ 2104 struct sockaddr_un addr; 2105 socklen_t sun_len; 2106 int sock; 2107 u_int pid; 2108 2109 if (muxclient_command == 0) { 2110 if (stdio_forward_host != NULL) 2111 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2112 else 2113 muxclient_command = SSHMUX_COMMAND_OPEN; 2114 } 2115 2116 switch (options.control_master) { 2117 case SSHCTL_MASTER_AUTO: 2118 case SSHCTL_MASTER_AUTO_ASK: 2119 debug("auto-mux: Trying existing master"); 2120 /* FALLTHROUGH */ 2121 case SSHCTL_MASTER_NO: 2122 break; 2123 default: 2124 return; 2125 } 2126 2127 memset(&addr, '\0', sizeof(addr)); 2128 addr.sun_family = AF_UNIX; 2129 sun_len = offsetof(struct sockaddr_un, sun_path) + 2130 strlen(path) + 1; 2131 2132 if (strlcpy(addr.sun_path, path, 2133 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2134 fatal("ControlPath too long"); 2135 2136 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2137 fatal("%s socket(): %s", __func__, strerror(errno)); 2138 2139 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2140 switch (muxclient_command) { 2141 case SSHMUX_COMMAND_OPEN: 2142 case SSHMUX_COMMAND_STDIO_FWD: 2143 break; 2144 default: 2145 fatal("Control socket connect(%.100s): %s", path, 2146 strerror(errno)); 2147 } 2148 if (errno == ECONNREFUSED && 2149 options.control_master != SSHCTL_MASTER_NO) { 2150 debug("Stale control socket %.100s, unlinking", path); 2151 unlink(path); 2152 } else if (errno == ENOENT) { 2153 debug("Control socket \"%.100s\" does not exist", path); 2154 } else { 2155 error("Control socket connect(%.100s): %s", path, 2156 strerror(errno)); 2157 } 2158 close(sock); 2159 return; 2160 } 2161 set_nonblock(sock); 2162 2163 if (mux_client_hello_exchange(sock) != 0) { 2164 error("%s: master hello exchange failed", __func__); 2165 close(sock); 2166 return; 2167 } 2168 2169 switch (muxclient_command) { 2170 case SSHMUX_COMMAND_ALIVE_CHECK: 2171 if ((pid = mux_client_request_alive(sock)) == 0) 2172 fatal("%s: master alive check failed", __func__); 2173 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2174 exit(0); 2175 case SSHMUX_COMMAND_TERMINATE: 2176 mux_client_request_terminate(sock); 2177 fprintf(stderr, "Exit request sent.\r\n"); 2178 exit(0); 2179 case SSHMUX_COMMAND_FORWARD: 2180 if (mux_client_forwards(sock, 0) != 0) 2181 fatal("%s: master forward request failed", __func__); 2182 exit(0); 2183 case SSHMUX_COMMAND_OPEN: 2184 if (mux_client_forwards(sock, 0) != 0) { 2185 error("%s: master forward request failed", __func__); 2186 return; 2187 } 2188 mux_client_request_session(sock); 2189 return; 2190 case SSHMUX_COMMAND_STDIO_FWD: 2191 mux_client_request_stdio_fwd(sock); 2192 exit(0); 2193 case SSHMUX_COMMAND_STOP: 2194 mux_client_request_stop_listening(sock); 2195 fprintf(stderr, "Stop listening request sent.\r\n"); 2196 exit(0); 2197 case SSHMUX_COMMAND_CANCEL_FWD: 2198 if (mux_client_forwards(sock, 1) != 0) 2199 error("%s: master cancel forward request failed", 2200 __func__); 2201 exit(0); 2202 default: 2203 fatal("unrecognised muxclient_command %d", muxclient_command); 2204 } 2205} 2206