mux.c revision 294328
1/* $OpenBSD: mux.c,v 1.48 2014/07/17 07:22:19 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: head/crypto/openssh/mux.c 294328 2016-01-19 16:18:26Z 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 stdio fwd open confirmation callback */ 110struct mux_stdio_confirm_ctx { 111 u_int rid; 112}; 113 114/* Context for global channel callback */ 115struct mux_channel_confirm_ctx { 116 u_int cid; /* channel id */ 117 u_int rid; /* request id */ 118 int fid; /* forward id */ 119}; 120 121/* fd to control socket */ 122int muxserver_sock = -1; 123 124/* client request id */ 125u_int muxclient_request_id = 0; 126 127/* Multiplexing control command */ 128u_int muxclient_command = 0; 129 130/* Set when signalled. */ 131static volatile sig_atomic_t muxclient_terminate = 0; 132 133/* PID of multiplex server */ 134static u_int muxserver_pid = 0; 135 136static Channel *mux_listener_channel = NULL; 137 138struct mux_master_state { 139 int hello_rcvd; 140}; 141 142/* mux protocol messages */ 143#define MUX_MSG_HELLO 0x00000001 144#define MUX_C_NEW_SESSION 0x10000002 145#define MUX_C_ALIVE_CHECK 0x10000004 146#define MUX_C_TERMINATE 0x10000005 147#define MUX_C_OPEN_FWD 0x10000006 148#define MUX_C_CLOSE_FWD 0x10000007 149#define MUX_C_NEW_STDIO_FWD 0x10000008 150#define MUX_C_STOP_LISTENING 0x10000009 151#define MUX_S_OK 0x80000001 152#define MUX_S_PERMISSION_DENIED 0x80000002 153#define MUX_S_FAILURE 0x80000003 154#define MUX_S_EXIT_MESSAGE 0x80000004 155#define MUX_S_ALIVE 0x80000005 156#define MUX_S_SESSION_OPENED 0x80000006 157#define MUX_S_REMOTE_PORT 0x80000007 158#define MUX_S_TTY_ALLOC_FAIL 0x80000008 159 160/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 161#define MUX_FWD_LOCAL 1 162#define MUX_FWD_REMOTE 2 163#define MUX_FWD_DYNAMIC 3 164 165static void mux_session_confirm(int, int, void *); 166static void mux_stdio_confirm(int, int, void *); 167 168static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 169static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 170static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 171static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 172static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 173static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 174static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 175static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 176 177static const struct { 178 u_int type; 179 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 180} mux_master_handlers[] = { 181 { MUX_MSG_HELLO, process_mux_master_hello }, 182 { MUX_C_NEW_SESSION, process_mux_new_session }, 183 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 184 { MUX_C_TERMINATE, process_mux_terminate }, 185 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 186 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 187 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 188 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 189 { 0, NULL } 190}; 191 192/* Cleanup callback fired on closure of mux slave _session_ channel */ 193/* ARGSUSED */ 194static void 195mux_master_session_cleanup_cb(int cid, void *unused) 196{ 197 Channel *cc, *c = channel_by_id(cid); 198 199 debug3("%s: entering for channel %d", __func__, cid); 200 if (c == NULL) 201 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 202 if (c->ctl_chan != -1) { 203 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 204 fatal("%s: channel %d missing control channel %d", 205 __func__, c->self, c->ctl_chan); 206 c->ctl_chan = -1; 207 cc->remote_id = -1; 208 chan_rcvd_oclose(cc); 209 } 210 channel_cancel_cleanup(c->self); 211} 212 213/* Cleanup callback fired on closure of mux slave _control_ channel */ 214/* ARGSUSED */ 215static void 216mux_master_control_cleanup_cb(int cid, void *unused) 217{ 218 Channel *sc, *c = channel_by_id(cid); 219 220 debug3("%s: entering for channel %d", __func__, cid); 221 if (c == NULL) 222 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 223 if (c->remote_id != -1) { 224 if ((sc = channel_by_id(c->remote_id)) == NULL) 225 fatal("%s: channel %d missing session channel %d", 226 __func__, c->self, c->remote_id); 227 c->remote_id = -1; 228 sc->ctl_chan = -1; 229 if (sc->type != SSH_CHANNEL_OPEN && 230 sc->type != SSH_CHANNEL_OPENING) { 231 debug2("%s: channel %d: not open", __func__, sc->self); 232 chan_mark_dead(sc); 233 } else { 234 if (sc->istate == CHAN_INPUT_OPEN) 235 chan_read_failed(sc); 236 if (sc->ostate == CHAN_OUTPUT_OPEN) 237 chan_write_failed(sc); 238 } 239 } 240 channel_cancel_cleanup(c->self); 241} 242 243/* Check mux client environment variables before passing them to mux master. */ 244static int 245env_permitted(char *env) 246{ 247 int i, ret; 248 char name[1024], *cp; 249 250 if ((cp = strchr(env, '=')) == NULL || cp == env) 251 return 0; 252 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 253 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 254 error("env_permitted: name '%.100s...' too long", env); 255 return 0; 256 } 257 258 for (i = 0; i < options.num_send_env; i++) 259 if (match_pattern(name, options.send_env[i])) 260 return 1; 261 262 return 0; 263} 264 265/* Mux master protocol message handlers */ 266 267static int 268process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 269{ 270 u_int ver; 271 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 272 273 if (state == NULL) 274 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 275 if (state->hello_rcvd) { 276 error("%s: HELLO received twice", __func__); 277 return -1; 278 } 279 if (buffer_get_int_ret(&ver, m) != 0) { 280 malf: 281 error("%s: malformed message", __func__); 282 return -1; 283 } 284 if (ver != SSHMUX_VER) { 285 error("Unsupported multiplexing protocol version %d " 286 "(expected %d)", ver, SSHMUX_VER); 287 return -1; 288 } 289 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 290 291 /* No extensions are presently defined */ 292 while (buffer_len(m) > 0) { 293 char *name = buffer_get_string_ret(m, NULL); 294 char *value = buffer_get_string_ret(m, NULL); 295 296 if (name == NULL || value == NULL) { 297 free(name); 298 free(value); 299 goto malf; 300 } 301 debug2("Unrecognised slave extension \"%s\"", name); 302 free(name); 303 free(value); 304 } 305 state->hello_rcvd = 1; 306 return 0; 307} 308 309static int 310process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 311{ 312 Channel *nc; 313 struct mux_session_confirm_ctx *cctx; 314 char *reserved, *cmd, *cp; 315 u_int i, j, len, env_len, escape_char, window, packetmax; 316 int new_fd[3]; 317 318 /* Reply for SSHMUX_COMMAND_OPEN */ 319 cctx = xcalloc(1, sizeof(*cctx)); 320 cctx->term = NULL; 321 cctx->rid = rid; 322 cmd = reserved = NULL; 323 cctx->env = NULL; 324 env_len = 0; 325 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 326 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 327 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 328 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 329 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 330 buffer_get_int_ret(&escape_char, m) != 0 || 331 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 332 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 333 malf: 334 free(cmd); 335 free(reserved); 336 for (j = 0; j < env_len; j++) 337 free(cctx->env[j]); 338 free(cctx->env); 339 free(cctx->term); 340 free(cctx); 341 error("%s: malformed message", __func__); 342 return -1; 343 } 344 free(reserved); 345 reserved = NULL; 346 347 while (buffer_len(m) > 0) { 348#define MUX_MAX_ENV_VARS 4096 349 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 350 goto malf; 351 if (!env_permitted(cp)) { 352 free(cp); 353 continue; 354 } 355 cctx->env = xrealloc(cctx->env, env_len + 2, 356 sizeof(*cctx->env)); 357 cctx->env[env_len++] = cp; 358 cctx->env[env_len] = NULL; 359 if (env_len > MUX_MAX_ENV_VARS) { 360 error(">%d environment variables received, ignoring " 361 "additional", MUX_MAX_ENV_VARS); 362 break; 363 } 364 } 365 366 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 367 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 368 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 369 cctx->want_subsys, cctx->term, cmd, env_len); 370 371 buffer_init(&cctx->cmd); 372 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 373 free(cmd); 374 cmd = NULL; 375 376 /* Gather fds from client */ 377 for(i = 0; i < 3; i++) { 378 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 379 error("%s: failed to receive fd %d from slave", 380 __func__, i); 381 for (j = 0; j < i; j++) 382 close(new_fd[j]); 383 for (j = 0; j < env_len; j++) 384 free(cctx->env[j]); 385 free(cctx->env); 386 free(cctx->term); 387 buffer_free(&cctx->cmd); 388 free(cctx); 389 390 /* prepare reply */ 391 buffer_put_int(r, MUX_S_FAILURE); 392 buffer_put_int(r, rid); 393 buffer_put_cstring(r, 394 "did not receive file descriptors"); 395 return -1; 396 } 397 } 398 399 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 400 new_fd[0], new_fd[1], new_fd[2]); 401 402 /* XXX support multiple child sessions in future */ 403 if (c->remote_id != -1) { 404 debug2("%s: session already open", __func__); 405 /* prepare reply */ 406 buffer_put_int(r, MUX_S_FAILURE); 407 buffer_put_int(r, rid); 408 buffer_put_cstring(r, "Multiple sessions not supported"); 409 cleanup: 410 close(new_fd[0]); 411 close(new_fd[1]); 412 close(new_fd[2]); 413 free(cctx->term); 414 if (env_len != 0) { 415 for (i = 0; i < env_len; i++) 416 free(cctx->env[i]); 417 free(cctx->env); 418 } 419 buffer_free(&cctx->cmd); 420 free(cctx); 421 return 0; 422 } 423 424 if (options.control_master == SSHCTL_MASTER_ASK || 425 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 426 if (!ask_permission("Allow shared connection to %s? ", host)) { 427 debug2("%s: session refused by user", __func__); 428 /* prepare reply */ 429 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 430 buffer_put_int(r, rid); 431 buffer_put_cstring(r, "Permission denied"); 432 goto cleanup; 433 } 434 } 435 436 /* Try to pick up ttymodes from client before it goes raw */ 437 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 438 error("%s: tcgetattr: %s", __func__, strerror(errno)); 439 440 /* enable nonblocking unless tty */ 441 if (!isatty(new_fd[0])) 442 set_nonblock(new_fd[0]); 443 if (!isatty(new_fd[1])) 444 set_nonblock(new_fd[1]); 445 if (!isatty(new_fd[2])) 446 set_nonblock(new_fd[2]); 447 448 window = CHAN_SES_WINDOW_DEFAULT; 449 packetmax = CHAN_SES_PACKET_DEFAULT; 450 if (cctx->want_tty) { 451 window >>= 1; 452 packetmax >>= 1; 453 } 454 455 nc = channel_new("session", SSH_CHANNEL_OPENING, 456 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 457 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 458 459 nc->ctl_chan = c->self; /* link session -> control channel */ 460 c->remote_id = nc->self; /* link control -> session channel */ 461 462 if (cctx->want_tty && escape_char != 0xffffffff) { 463 channel_register_filter(nc->self, 464 client_simple_escape_filter, NULL, 465 client_filter_cleanup, 466 client_new_escape_filter_ctx((int)escape_char)); 467 } 468 469 debug2("%s: channel_new: %d linked to control channel %d", 470 __func__, nc->self, nc->ctl_chan); 471 472 channel_send_open(nc->self); 473 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 474 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 475 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 476 477 /* reply is deferred, sent by mux_session_confirm */ 478 return 0; 479} 480 481static int 482process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 483{ 484 debug2("%s: channel %d: alive check", __func__, c->self); 485 486 /* prepare reply */ 487 buffer_put_int(r, MUX_S_ALIVE); 488 buffer_put_int(r, rid); 489 buffer_put_int(r, (u_int)getpid()); 490 491 return 0; 492} 493 494static int 495process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 496{ 497 debug2("%s: channel %d: terminate request", __func__, c->self); 498 499 if (options.control_master == SSHCTL_MASTER_ASK || 500 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 501 if (!ask_permission("Terminate shared connection to %s? ", 502 host)) { 503 debug2("%s: termination refused by user", __func__); 504 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 505 buffer_put_int(r, rid); 506 buffer_put_cstring(r, "Permission denied"); 507 return 0; 508 } 509 } 510 511 quit_pending = 1; 512 buffer_put_int(r, MUX_S_OK); 513 buffer_put_int(r, rid); 514 /* XXX exit happens too soon - message never makes it to client */ 515 return 0; 516} 517 518static char * 519format_forward(u_int ftype, struct Forward *fwd) 520{ 521 char *ret; 522 523 switch (ftype) { 524 case MUX_FWD_LOCAL: 525 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 526 (fwd->listen_path != NULL) ? fwd->listen_path : 527 (fwd->listen_host == NULL) ? 528 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 529 fwd->listen_host, fwd->listen_port, 530 (fwd->connect_path != NULL) ? fwd->connect_path : 531 fwd->connect_host, fwd->connect_port); 532 break; 533 case MUX_FWD_DYNAMIC: 534 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 535 (fwd->listen_host == NULL) ? 536 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 537 fwd->listen_host, fwd->listen_port); 538 break; 539 case MUX_FWD_REMOTE: 540 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 541 (fwd->listen_path != NULL) ? fwd->listen_path : 542 (fwd->listen_host == NULL) ? 543 "LOCALHOST" : fwd->listen_host, 544 fwd->listen_port, 545 (fwd->connect_path != NULL) ? fwd->connect_path : 546 fwd->connect_host, fwd->connect_port); 547 break; 548 default: 549 fatal("%s: unknown forward type %u", __func__, ftype); 550 } 551 return ret; 552} 553 554static int 555compare_host(const char *a, const char *b) 556{ 557 if (a == NULL && b == NULL) 558 return 1; 559 if (a == NULL || b == NULL) 560 return 0; 561 return strcmp(a, b) == 0; 562} 563 564static int 565compare_forward(struct Forward *a, struct Forward *b) 566{ 567 if (!compare_host(a->listen_host, b->listen_host)) 568 return 0; 569 if (!compare_host(a->listen_path, b->listen_path)) 570 return 0; 571 if (a->listen_port != b->listen_port) 572 return 0; 573 if (!compare_host(a->connect_host, b->connect_host)) 574 return 0; 575 if (!compare_host(a->connect_path, b->connect_path)) 576 return 0; 577 if (a->connect_port != b->connect_port) 578 return 0; 579 580 return 1; 581} 582 583static void 584mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 585{ 586 struct mux_channel_confirm_ctx *fctx = ctxt; 587 char *failmsg = NULL; 588 struct Forward *rfwd; 589 Channel *c; 590 Buffer out; 591 592 if ((c = channel_by_id(fctx->cid)) == NULL) { 593 /* no channel for reply */ 594 error("%s: unknown channel", __func__); 595 return; 596 } 597 buffer_init(&out); 598 if (fctx->fid >= options.num_remote_forwards) { 599 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 600 goto fail; 601 } 602 rfwd = &options.remote_forwards[fctx->fid]; 603 debug("%s: %s for: listen %d, connect %s:%d", __func__, 604 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 605 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 606 rfwd->connect_host, rfwd->connect_port); 607 if (type == SSH2_MSG_REQUEST_SUCCESS) { 608 if (rfwd->listen_port == 0) { 609 rfwd->allocated_port = packet_get_int(); 610 logit("Allocated port %u for mux remote forward" 611 " to %s:%d", rfwd->allocated_port, 612 rfwd->connect_host, rfwd->connect_port); 613 buffer_put_int(&out, MUX_S_REMOTE_PORT); 614 buffer_put_int(&out, fctx->rid); 615 buffer_put_int(&out, rfwd->allocated_port); 616 channel_update_permitted_opens(rfwd->handle, 617 rfwd->allocated_port); 618 } else { 619 buffer_put_int(&out, MUX_S_OK); 620 buffer_put_int(&out, fctx->rid); 621 } 622 goto out; 623 } else { 624 if (rfwd->listen_port == 0) 625 channel_update_permitted_opens(rfwd->handle, -1); 626 if (rfwd->listen_path != NULL) 627 xasprintf(&failmsg, "remote port forwarding failed for " 628 "listen path %s", rfwd->listen_path); 629 else 630 xasprintf(&failmsg, "remote port forwarding failed for " 631 "listen port %d", rfwd->listen_port); 632 } 633 fail: 634 error("%s: %s", __func__, failmsg); 635 buffer_put_int(&out, MUX_S_FAILURE); 636 buffer_put_int(&out, fctx->rid); 637 buffer_put_cstring(&out, failmsg); 638 free(failmsg); 639 out: 640 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 641 buffer_free(&out); 642 if (c->mux_pause <= 0) 643 fatal("%s: mux_pause %d", __func__, c->mux_pause); 644 c->mux_pause = 0; /* start processing messages again */ 645} 646 647static int 648process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 649{ 650 struct Forward fwd; 651 char *fwd_desc = NULL; 652 char *listen_addr, *connect_addr; 653 u_int ftype; 654 u_int lport, cport; 655 int i, ret = 0, freefwd = 1; 656 657 /* XXX - lport/cport check redundant */ 658 if (buffer_get_int_ret(&ftype, m) != 0 || 659 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 660 buffer_get_int_ret(&lport, m) != 0 || 661 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 662 buffer_get_int_ret(&cport, m) != 0 || 663 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 664 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 665 error("%s: malformed message", __func__); 666 ret = -1; 667 goto out; 668 } 669 if (*listen_addr == '\0') { 670 free(listen_addr); 671 listen_addr = NULL; 672 } 673 if (*connect_addr == '\0') { 674 free(connect_addr); 675 connect_addr = NULL; 676 } 677 678 memset(&fwd, 0, sizeof(fwd)); 679 fwd.listen_port = lport; 680 if (fwd.listen_port == PORT_STREAMLOCAL) 681 fwd.listen_path = listen_addr; 682 else 683 fwd.listen_host = listen_addr; 684 fwd.connect_port = cport; 685 if (fwd.connect_port == PORT_STREAMLOCAL) 686 fwd.connect_path = connect_addr; 687 else 688 fwd.connect_host = connect_addr; 689 690 debug2("%s: channel %d: request %s", __func__, c->self, 691 (fwd_desc = format_forward(ftype, &fwd))); 692 693 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 694 ftype != MUX_FWD_DYNAMIC) { 695 logit("%s: invalid forwarding type %u", __func__, ftype); 696 invalid: 697 free(listen_addr); 698 free(connect_addr); 699 buffer_put_int(r, MUX_S_FAILURE); 700 buffer_put_int(r, rid); 701 buffer_put_cstring(r, "Invalid forwarding request"); 702 return 0; 703 } 704 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 705 logit("%s: streamlocal and dynamic forwards " 706 "are mutually exclusive", __func__); 707 goto invalid; 708 } 709 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 710 logit("%s: invalid listen port %u", __func__, 711 fwd.listen_port); 712 goto invalid; 713 } 714 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 715 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 716 logit("%s: invalid connect port %u", __func__, 717 fwd.connect_port); 718 goto invalid; 719 } 720 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 721 logit("%s: missing connect host", __func__); 722 goto invalid; 723 } 724 725 /* Skip forwards that have already been requested */ 726 switch (ftype) { 727 case MUX_FWD_LOCAL: 728 case MUX_FWD_DYNAMIC: 729 for (i = 0; i < options.num_local_forwards; i++) { 730 if (compare_forward(&fwd, 731 options.local_forwards + i)) { 732 exists: 733 debug2("%s: found existing forwarding", 734 __func__); 735 buffer_put_int(r, MUX_S_OK); 736 buffer_put_int(r, rid); 737 goto out; 738 } 739 } 740 break; 741 case MUX_FWD_REMOTE: 742 for (i = 0; i < options.num_remote_forwards; i++) { 743 if (compare_forward(&fwd, 744 options.remote_forwards + i)) { 745 if (fwd.listen_port != 0) 746 goto exists; 747 debug2("%s: found allocated port", 748 __func__); 749 buffer_put_int(r, MUX_S_REMOTE_PORT); 750 buffer_put_int(r, rid); 751 buffer_put_int(r, 752 options.remote_forwards[i].allocated_port); 753 goto out; 754 } 755 } 756 break; 757 } 758 759 if (options.control_master == SSHCTL_MASTER_ASK || 760 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 761 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 762 debug2("%s: forwarding refused by user", __func__); 763 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 764 buffer_put_int(r, rid); 765 buffer_put_cstring(r, "Permission denied"); 766 goto out; 767 } 768 } 769 770 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 771 if (!channel_setup_local_fwd_listener(&fwd, 772 &options.fwd_opts)) { 773 fail: 774 logit("slave-requested %s failed", fwd_desc); 775 buffer_put_int(r, MUX_S_FAILURE); 776 buffer_put_int(r, rid); 777 buffer_put_cstring(r, "Port forwarding failed"); 778 goto out; 779 } 780 add_local_forward(&options, &fwd); 781 freefwd = 0; 782 } else { 783 struct mux_channel_confirm_ctx *fctx; 784 785 fwd.handle = channel_request_remote_forwarding(&fwd); 786 if (fwd.handle < 0) 787 goto fail; 788 add_remote_forward(&options, &fwd); 789 fctx = xcalloc(1, sizeof(*fctx)); 790 fctx->cid = c->self; 791 fctx->rid = rid; 792 fctx->fid = options.num_remote_forwards - 1; 793 client_register_global_confirm(mux_confirm_remote_forward, 794 fctx); 795 freefwd = 0; 796 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 797 /* delayed reply in mux_confirm_remote_forward */ 798 goto out; 799 } 800 buffer_put_int(r, MUX_S_OK); 801 buffer_put_int(r, rid); 802 out: 803 free(fwd_desc); 804 if (freefwd) { 805 free(fwd.listen_host); 806 free(fwd.listen_path); 807 free(fwd.connect_host); 808 free(fwd.connect_path); 809 } 810 return ret; 811} 812 813static int 814process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 815{ 816 struct Forward fwd, *found_fwd; 817 char *fwd_desc = NULL; 818 const char *error_reason = NULL; 819 char *listen_addr = NULL, *connect_addr = NULL; 820 u_int ftype; 821 int i, ret = 0; 822 u_int lport, cport; 823 824 if (buffer_get_int_ret(&ftype, m) != 0 || 825 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 826 buffer_get_int_ret(&lport, m) != 0 || 827 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 828 buffer_get_int_ret(&cport, m) != 0 || 829 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 830 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 831 error("%s: malformed message", __func__); 832 ret = -1; 833 goto out; 834 } 835 836 if (*listen_addr == '\0') { 837 free(listen_addr); 838 listen_addr = NULL; 839 } 840 if (*connect_addr == '\0') { 841 free(connect_addr); 842 connect_addr = NULL; 843 } 844 845 memset(&fwd, 0, sizeof(fwd)); 846 fwd.listen_port = lport; 847 if (fwd.listen_port == PORT_STREAMLOCAL) 848 fwd.listen_path = listen_addr; 849 else 850 fwd.listen_host = listen_addr; 851 fwd.connect_port = cport; 852 if (fwd.connect_port == PORT_STREAMLOCAL) 853 fwd.connect_path = connect_addr; 854 else 855 fwd.connect_host = connect_addr; 856 857 debug2("%s: channel %d: request cancel %s", __func__, c->self, 858 (fwd_desc = format_forward(ftype, &fwd))); 859 860 /* make sure this has been requested */ 861 found_fwd = NULL; 862 switch (ftype) { 863 case MUX_FWD_LOCAL: 864 case MUX_FWD_DYNAMIC: 865 for (i = 0; i < options.num_local_forwards; i++) { 866 if (compare_forward(&fwd, 867 options.local_forwards + i)) { 868 found_fwd = options.local_forwards + i; 869 break; 870 } 871 } 872 break; 873 case MUX_FWD_REMOTE: 874 for (i = 0; i < options.num_remote_forwards; i++) { 875 if (compare_forward(&fwd, 876 options.remote_forwards + i)) { 877 found_fwd = options.remote_forwards + i; 878 break; 879 } 880 } 881 break; 882 } 883 884 if (found_fwd == NULL) 885 error_reason = "port not forwarded"; 886 else if (ftype == MUX_FWD_REMOTE) { 887 /* 888 * This shouldn't fail unless we confused the host/port 889 * between options.remote_forwards and permitted_opens. 890 * However, for dynamic allocated listen ports we need 891 * to use the actual listen port. 892 */ 893 if (channel_request_rforward_cancel(found_fwd) == -1) 894 error_reason = "port not in permitted opens"; 895 } else { /* local and dynamic forwards */ 896 /* Ditto */ 897 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 898 &options.fwd_opts) == -1) 899 error_reason = "port not found"; 900 } 901 902 if (error_reason == NULL) { 903 buffer_put_int(r, MUX_S_OK); 904 buffer_put_int(r, rid); 905 906 free(found_fwd->listen_host); 907 free(found_fwd->listen_path); 908 free(found_fwd->connect_host); 909 free(found_fwd->connect_path); 910 found_fwd->listen_host = found_fwd->connect_host = NULL; 911 found_fwd->listen_path = found_fwd->connect_path = NULL; 912 found_fwd->listen_port = found_fwd->connect_port = 0; 913 } else { 914 buffer_put_int(r, MUX_S_FAILURE); 915 buffer_put_int(r, rid); 916 buffer_put_cstring(r, error_reason); 917 } 918 out: 919 free(fwd_desc); 920 free(listen_addr); 921 free(connect_addr); 922 923 return ret; 924} 925 926static int 927process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 928{ 929 Channel *nc; 930 char *reserved, *chost; 931 u_int cport, i, j; 932 int new_fd[2]; 933 struct mux_stdio_confirm_ctx *cctx; 934 935 chost = reserved = NULL; 936 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 937 (chost = buffer_get_string_ret(m, NULL)) == NULL || 938 buffer_get_int_ret(&cport, m) != 0) { 939 free(reserved); 940 free(chost); 941 error("%s: malformed message", __func__); 942 return -1; 943 } 944 free(reserved); 945 946 debug2("%s: channel %d: request stdio fwd to %s:%u", 947 __func__, c->self, chost, cport); 948 949 /* Gather fds from client */ 950 for(i = 0; i < 2; i++) { 951 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 952 error("%s: failed to receive fd %d from slave", 953 __func__, i); 954 for (j = 0; j < i; j++) 955 close(new_fd[j]); 956 free(chost); 957 958 /* prepare reply */ 959 buffer_put_int(r, MUX_S_FAILURE); 960 buffer_put_int(r, rid); 961 buffer_put_cstring(r, 962 "did not receive file descriptors"); 963 return -1; 964 } 965 } 966 967 debug3("%s: got fds stdin %d, stdout %d", __func__, 968 new_fd[0], new_fd[1]); 969 970 /* XXX support multiple child sessions in future */ 971 if (c->remote_id != -1) { 972 debug2("%s: session already open", __func__); 973 /* prepare reply */ 974 buffer_put_int(r, MUX_S_FAILURE); 975 buffer_put_int(r, rid); 976 buffer_put_cstring(r, "Multiple sessions not supported"); 977 cleanup: 978 close(new_fd[0]); 979 close(new_fd[1]); 980 free(chost); 981 return 0; 982 } 983 984 if (options.control_master == SSHCTL_MASTER_ASK || 985 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 986 if (!ask_permission("Allow forward to %s:%u? ", 987 chost, cport)) { 988 debug2("%s: stdio fwd refused by user", __func__); 989 /* prepare reply */ 990 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 991 buffer_put_int(r, rid); 992 buffer_put_cstring(r, "Permission denied"); 993 goto cleanup; 994 } 995 } 996 997 /* enable nonblocking unless tty */ 998 if (!isatty(new_fd[0])) 999 set_nonblock(new_fd[0]); 1000 if (!isatty(new_fd[1])) 1001 set_nonblock(new_fd[1]); 1002 1003 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1004 1005 nc->ctl_chan = c->self; /* link session -> control channel */ 1006 c->remote_id = nc->self; /* link control -> session channel */ 1007 1008 debug2("%s: channel_new: %d linked to control channel %d", 1009 __func__, nc->self, nc->ctl_chan); 1010 1011 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1012 1013 cctx = xcalloc(1, sizeof(*cctx)); 1014 cctx->rid = rid; 1015 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1016 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1017 1018 /* reply is deferred, sent by mux_session_confirm */ 1019 return 0; 1020} 1021 1022/* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1023static void 1024mux_stdio_confirm(int id, int success, void *arg) 1025{ 1026 struct mux_stdio_confirm_ctx *cctx = arg; 1027 Channel *c, *cc; 1028 Buffer reply; 1029 1030 if (cctx == NULL) 1031 fatal("%s: cctx == NULL", __func__); 1032 if ((c = channel_by_id(id)) == NULL) 1033 fatal("%s: no channel for id %d", __func__, id); 1034 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1035 fatal("%s: channel %d lacks control channel %d", __func__, 1036 id, c->ctl_chan); 1037 1038 if (!success) { 1039 debug3("%s: sending failure reply", __func__); 1040 /* prepare reply */ 1041 buffer_init(&reply); 1042 buffer_put_int(&reply, MUX_S_FAILURE); 1043 buffer_put_int(&reply, cctx->rid); 1044 buffer_put_cstring(&reply, "Session open refused by peer"); 1045 goto done; 1046 } 1047 1048 debug3("%s: sending success reply", __func__); 1049 /* prepare reply */ 1050 buffer_init(&reply); 1051 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1052 buffer_put_int(&reply, cctx->rid); 1053 buffer_put_int(&reply, c->self); 1054 1055 done: 1056 /* Send reply */ 1057 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1058 buffer_free(&reply); 1059 1060 if (cc->mux_pause <= 0) 1061 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1062 cc->mux_pause = 0; /* start processing messages again */ 1063 c->open_confirm_ctx = NULL; 1064 free(cctx); 1065} 1066 1067static int 1068process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1069{ 1070 debug("%s: channel %d: stop listening", __func__, c->self); 1071 1072 if (options.control_master == SSHCTL_MASTER_ASK || 1073 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1074 if (!ask_permission("Disable further multiplexing on shared " 1075 "connection to %s? ", host)) { 1076 debug2("%s: stop listen refused by user", __func__); 1077 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1078 buffer_put_int(r, rid); 1079 buffer_put_cstring(r, "Permission denied"); 1080 return 0; 1081 } 1082 } 1083 1084 if (mux_listener_channel != NULL) { 1085 channel_free(mux_listener_channel); 1086 client_stop_mux(); 1087 free(options.control_path); 1088 options.control_path = NULL; 1089 mux_listener_channel = NULL; 1090 muxserver_sock = -1; 1091 } 1092 1093 /* prepare reply */ 1094 buffer_put_int(r, MUX_S_OK); 1095 buffer_put_int(r, rid); 1096 1097 return 0; 1098} 1099 1100/* Channel callbacks fired on read/write from mux slave fd */ 1101static int 1102mux_master_read_cb(Channel *c) 1103{ 1104 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1105 Buffer in, out; 1106 const u_char *ptr; 1107 u_int type, rid, have, i; 1108 int ret = -1; 1109 1110 /* Setup ctx and */ 1111 if (c->mux_ctx == NULL) { 1112 state = xcalloc(1, sizeof(*state)); 1113 c->mux_ctx = state; 1114 channel_register_cleanup(c->self, 1115 mux_master_control_cleanup_cb, 0); 1116 1117 /* Send hello */ 1118 buffer_init(&out); 1119 buffer_put_int(&out, MUX_MSG_HELLO); 1120 buffer_put_int(&out, SSHMUX_VER); 1121 /* no extensions */ 1122 buffer_put_string(&c->output, buffer_ptr(&out), 1123 buffer_len(&out)); 1124 buffer_free(&out); 1125 debug3("%s: channel %d: hello sent", __func__, c->self); 1126 return 0; 1127 } 1128 1129 buffer_init(&in); 1130 buffer_init(&out); 1131 1132 /* Channel code ensures that we receive whole packets */ 1133 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1134 malf: 1135 error("%s: malformed message", __func__); 1136 goto out; 1137 } 1138 buffer_append(&in, ptr, have); 1139 1140 if (buffer_get_int_ret(&type, &in) != 0) 1141 goto malf; 1142 debug3("%s: channel %d packet type 0x%08x len %u", 1143 __func__, c->self, type, buffer_len(&in)); 1144 1145 if (type == MUX_MSG_HELLO) 1146 rid = 0; 1147 else { 1148 if (!state->hello_rcvd) { 1149 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1150 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1151 goto out; 1152 } 1153 if (buffer_get_int_ret(&rid, &in) != 0) 1154 goto malf; 1155 } 1156 1157 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1158 if (type == mux_master_handlers[i].type) { 1159 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1160 break; 1161 } 1162 } 1163 if (mux_master_handlers[i].handler == NULL) { 1164 error("%s: unsupported mux message 0x%08x", __func__, type); 1165 buffer_put_int(&out, MUX_S_FAILURE); 1166 buffer_put_int(&out, rid); 1167 buffer_put_cstring(&out, "unsupported request"); 1168 ret = 0; 1169 } 1170 /* Enqueue reply packet */ 1171 if (buffer_len(&out) != 0) { 1172 buffer_put_string(&c->output, buffer_ptr(&out), 1173 buffer_len(&out)); 1174 } 1175 out: 1176 buffer_free(&in); 1177 buffer_free(&out); 1178 return ret; 1179} 1180 1181void 1182mux_exit_message(Channel *c, int exitval) 1183{ 1184 Buffer m; 1185 Channel *mux_chan; 1186 1187 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1188 exitval); 1189 1190 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1191 fatal("%s: channel %d missing mux channel %d", 1192 __func__, c->self, c->ctl_chan); 1193 1194 /* Append exit message packet to control socket output queue */ 1195 buffer_init(&m); 1196 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1197 buffer_put_int(&m, c->self); 1198 buffer_put_int(&m, exitval); 1199 1200 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1201 buffer_free(&m); 1202} 1203 1204void 1205mux_tty_alloc_failed(Channel *c) 1206{ 1207 Buffer m; 1208 Channel *mux_chan; 1209 1210 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1211 1212 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1213 fatal("%s: channel %d missing mux channel %d", 1214 __func__, c->self, c->ctl_chan); 1215 1216 /* Append exit message packet to control socket output queue */ 1217 buffer_init(&m); 1218 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1219 buffer_put_int(&m, c->self); 1220 1221 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1222 buffer_free(&m); 1223} 1224 1225/* Prepare a mux master to listen on a Unix domain socket. */ 1226void 1227muxserver_listen(void) 1228{ 1229 mode_t old_umask; 1230 char *orig_control_path = options.control_path; 1231 char rbuf[16+1]; 1232 u_int i, r; 1233 int oerrno; 1234 1235 if (options.control_path == NULL || 1236 options.control_master == SSHCTL_MASTER_NO) 1237 return; 1238 1239 debug("setting up multiplex master socket"); 1240 1241 /* 1242 * Use a temporary path before listen so we can pseudo-atomically 1243 * establish the listening socket in its final location to avoid 1244 * other processes racing in between bind() and listen() and hitting 1245 * an unready socket. 1246 */ 1247 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1248 r = arc4random_uniform(26+26+10); 1249 rbuf[i] = (r < 26) ? 'a' + r : 1250 (r < 26*2) ? 'A' + r - 26 : 1251 '0' + r - 26 - 26; 1252 } 1253 rbuf[sizeof(rbuf) - 1] = '\0'; 1254 options.control_path = NULL; 1255 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1256 debug3("%s: temporary control path %s", __func__, options.control_path); 1257 1258 old_umask = umask(0177); 1259 muxserver_sock = unix_listener(options.control_path, 64, 0); 1260 oerrno = errno; 1261 umask(old_umask); 1262 if (muxserver_sock < 0) { 1263 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1264 error("ControlSocket %s already exists, " 1265 "disabling multiplexing", options.control_path); 1266 disable_mux_master: 1267 if (muxserver_sock != -1) { 1268 close(muxserver_sock); 1269 muxserver_sock = -1; 1270 } 1271 free(orig_control_path); 1272 free(options.control_path); 1273 options.control_path = NULL; 1274 options.control_master = SSHCTL_MASTER_NO; 1275 return; 1276 } else { 1277 /* unix_listener() logs the error */ 1278 cleanup_exit(255); 1279 } 1280 } 1281 1282 /* Now atomically "move" the mux socket into position */ 1283 if (link(options.control_path, orig_control_path) != 0) { 1284 if (errno != EEXIST) { 1285 fatal("%s: link mux listener %s => %s: %s", __func__, 1286 options.control_path, orig_control_path, 1287 strerror(errno)); 1288 } 1289 error("ControlSocket %s already exists, disabling multiplexing", 1290 orig_control_path); 1291 unlink(options.control_path); 1292 goto disable_mux_master; 1293 } 1294 unlink(options.control_path); 1295 free(options.control_path); 1296 options.control_path = orig_control_path; 1297 1298 set_nonblock(muxserver_sock); 1299 1300 mux_listener_channel = channel_new("mux listener", 1301 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1302 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1303 0, options.control_path, 1); 1304 mux_listener_channel->mux_rcb = mux_master_read_cb; 1305 debug3("%s: mux listener channel %d fd %d", __func__, 1306 mux_listener_channel->self, mux_listener_channel->sock); 1307} 1308 1309/* Callback on open confirmation in mux master for a mux client session. */ 1310static void 1311mux_session_confirm(int id, int success, void *arg) 1312{ 1313 struct mux_session_confirm_ctx *cctx = arg; 1314 const char *display; 1315 Channel *c, *cc; 1316 int i; 1317 Buffer reply; 1318 1319 if (cctx == NULL) 1320 fatal("%s: cctx == NULL", __func__); 1321 if ((c = channel_by_id(id)) == NULL) 1322 fatal("%s: no channel for id %d", __func__, id); 1323 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1324 fatal("%s: channel %d lacks control channel %d", __func__, 1325 id, c->ctl_chan); 1326 1327 if (!success) { 1328 debug3("%s: sending failure reply", __func__); 1329 /* prepare reply */ 1330 buffer_init(&reply); 1331 buffer_put_int(&reply, MUX_S_FAILURE); 1332 buffer_put_int(&reply, cctx->rid); 1333 buffer_put_cstring(&reply, "Session open refused by peer"); 1334 goto done; 1335 } 1336 1337 display = getenv("DISPLAY"); 1338 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1339 char *proto, *data; 1340 1341 /* Get reasonable local authentication information. */ 1342 client_x11_get_proto(display, options.xauth_location, 1343 options.forward_x11_trusted, options.forward_x11_timeout, 1344 &proto, &data); 1345 /* Request forwarding with authentication spoofing. */ 1346 debug("Requesting X11 forwarding with authentication " 1347 "spoofing."); 1348 x11_request_forwarding_with_spoofing(id, display, proto, 1349 data, 1); 1350 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1351 /* XXX exit_on_forward_failure */ 1352 } 1353 1354 if (cctx->want_agent_fwd && options.forward_agent) { 1355 debug("Requesting authentication agent forwarding."); 1356 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1357 packet_send(); 1358 } 1359 1360 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1361 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1362 1363 debug3("%s: sending success reply", __func__); 1364 /* prepare reply */ 1365 buffer_init(&reply); 1366 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1367 buffer_put_int(&reply, cctx->rid); 1368 buffer_put_int(&reply, c->self); 1369 1370 done: 1371 /* Send reply */ 1372 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1373 buffer_free(&reply); 1374 1375 if (cc->mux_pause <= 0) 1376 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1377 cc->mux_pause = 0; /* start processing messages again */ 1378 c->open_confirm_ctx = NULL; 1379 buffer_free(&cctx->cmd); 1380 free(cctx->term); 1381 if (cctx->env != NULL) { 1382 for (i = 0; cctx->env[i] != NULL; i++) 1383 free(cctx->env[i]); 1384 free(cctx->env); 1385 } 1386 free(cctx); 1387} 1388 1389/* ** Multiplexing client support */ 1390 1391/* Exit signal handler */ 1392static void 1393control_client_sighandler(int signo) 1394{ 1395 muxclient_terminate = signo; 1396} 1397 1398/* 1399 * Relay signal handler - used to pass some signals from mux client to 1400 * mux master. 1401 */ 1402static void 1403control_client_sigrelay(int signo) 1404{ 1405 int save_errno = errno; 1406 1407 if (muxserver_pid > 1) 1408 kill(muxserver_pid, signo); 1409 1410 errno = save_errno; 1411} 1412 1413static int 1414mux_client_read(int fd, Buffer *b, u_int need) 1415{ 1416 u_int have; 1417 ssize_t len; 1418 u_char *p; 1419 struct pollfd pfd; 1420 1421 pfd.fd = fd; 1422 pfd.events = POLLIN; 1423 p = buffer_append_space(b, need); 1424 for (have = 0; have < need; ) { 1425 if (muxclient_terminate) { 1426 errno = EINTR; 1427 return -1; 1428 } 1429 len = read(fd, p + have, need - have); 1430 if (len < 0) { 1431 switch (errno) { 1432#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1433 case EWOULDBLOCK: 1434#endif 1435 case EAGAIN: 1436 (void)poll(&pfd, 1, -1); 1437 /* FALLTHROUGH */ 1438 case EINTR: 1439 continue; 1440 default: 1441 return -1; 1442 } 1443 } 1444 if (len == 0) { 1445 errno = EPIPE; 1446 return -1; 1447 } 1448 have += (u_int)len; 1449 } 1450 return 0; 1451} 1452 1453static int 1454mux_client_write_packet(int fd, Buffer *m) 1455{ 1456 Buffer queue; 1457 u_int have, need; 1458 int oerrno, len; 1459 u_char *ptr; 1460 struct pollfd pfd; 1461 1462 pfd.fd = fd; 1463 pfd.events = POLLOUT; 1464 buffer_init(&queue); 1465 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1466 1467 need = buffer_len(&queue); 1468 ptr = buffer_ptr(&queue); 1469 1470 for (have = 0; have < need; ) { 1471 if (muxclient_terminate) { 1472 buffer_free(&queue); 1473 errno = EINTR; 1474 return -1; 1475 } 1476 len = write(fd, ptr + have, need - have); 1477 if (len < 0) { 1478 switch (errno) { 1479#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1480 case EWOULDBLOCK: 1481#endif 1482 case EAGAIN: 1483 (void)poll(&pfd, 1, -1); 1484 /* FALLTHROUGH */ 1485 case EINTR: 1486 continue; 1487 default: 1488 oerrno = errno; 1489 buffer_free(&queue); 1490 errno = oerrno; 1491 return -1; 1492 } 1493 } 1494 if (len == 0) { 1495 buffer_free(&queue); 1496 errno = EPIPE; 1497 return -1; 1498 } 1499 have += (u_int)len; 1500 } 1501 buffer_free(&queue); 1502 return 0; 1503} 1504 1505static int 1506mux_client_read_packet(int fd, Buffer *m) 1507{ 1508 Buffer queue; 1509 u_int need, have; 1510 const u_char *ptr; 1511 int oerrno; 1512 1513 buffer_init(&queue); 1514 if (mux_client_read(fd, &queue, 4) != 0) { 1515 if ((oerrno = errno) == EPIPE) 1516 debug3("%s: read header failed: %s", __func__, 1517 strerror(errno)); 1518 buffer_free(&queue); 1519 errno = oerrno; 1520 return -1; 1521 } 1522 need = get_u32(buffer_ptr(&queue)); 1523 if (mux_client_read(fd, &queue, need) != 0) { 1524 oerrno = errno; 1525 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1526 buffer_free(&queue); 1527 errno = oerrno; 1528 return -1; 1529 } 1530 ptr = buffer_get_string_ptr(&queue, &have); 1531 buffer_append(m, ptr, have); 1532 buffer_free(&queue); 1533 return 0; 1534} 1535 1536static int 1537mux_client_hello_exchange(int fd) 1538{ 1539 Buffer m; 1540 u_int type, ver; 1541 1542 buffer_init(&m); 1543 buffer_put_int(&m, MUX_MSG_HELLO); 1544 buffer_put_int(&m, SSHMUX_VER); 1545 /* no extensions */ 1546 1547 if (mux_client_write_packet(fd, &m) != 0) 1548 fatal("%s: write packet: %s", __func__, strerror(errno)); 1549 1550 buffer_clear(&m); 1551 1552 /* Read their HELLO */ 1553 if (mux_client_read_packet(fd, &m) != 0) { 1554 buffer_free(&m); 1555 return -1; 1556 } 1557 1558 type = buffer_get_int(&m); 1559 if (type != MUX_MSG_HELLO) 1560 fatal("%s: expected HELLO (%u) received %u", 1561 __func__, MUX_MSG_HELLO, type); 1562 ver = buffer_get_int(&m); 1563 if (ver != SSHMUX_VER) 1564 fatal("Unsupported multiplexing protocol version %d " 1565 "(expected %d)", ver, SSHMUX_VER); 1566 debug2("%s: master version %u", __func__, ver); 1567 /* No extensions are presently defined */ 1568 while (buffer_len(&m) > 0) { 1569 char *name = buffer_get_string(&m, NULL); 1570 char *value = buffer_get_string(&m, NULL); 1571 1572 debug2("Unrecognised master extension \"%s\"", name); 1573 free(name); 1574 free(value); 1575 } 1576 buffer_free(&m); 1577 return 0; 1578} 1579 1580static u_int 1581mux_client_request_alive(int fd) 1582{ 1583 Buffer m; 1584 char *e; 1585 u_int pid, type, rid; 1586 1587 debug3("%s: entering", __func__); 1588 1589 buffer_init(&m); 1590 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1591 buffer_put_int(&m, muxclient_request_id); 1592 1593 if (mux_client_write_packet(fd, &m) != 0) 1594 fatal("%s: write packet: %s", __func__, strerror(errno)); 1595 1596 buffer_clear(&m); 1597 1598 /* Read their reply */ 1599 if (mux_client_read_packet(fd, &m) != 0) { 1600 buffer_free(&m); 1601 return 0; 1602 } 1603 1604 type = buffer_get_int(&m); 1605 if (type != MUX_S_ALIVE) { 1606 e = buffer_get_string(&m, NULL); 1607 fatal("%s: master returned error: %s", __func__, e); 1608 } 1609 1610 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1611 fatal("%s: out of sequence reply: my id %u theirs %u", 1612 __func__, muxclient_request_id, rid); 1613 pid = buffer_get_int(&m); 1614 buffer_free(&m); 1615 1616 debug3("%s: done pid = %u", __func__, pid); 1617 1618 muxclient_request_id++; 1619 1620 return pid; 1621} 1622 1623static void 1624mux_client_request_terminate(int fd) 1625{ 1626 Buffer m; 1627 char *e; 1628 u_int type, rid; 1629 1630 debug3("%s: entering", __func__); 1631 1632 buffer_init(&m); 1633 buffer_put_int(&m, MUX_C_TERMINATE); 1634 buffer_put_int(&m, muxclient_request_id); 1635 1636 if (mux_client_write_packet(fd, &m) != 0) 1637 fatal("%s: write packet: %s", __func__, strerror(errno)); 1638 1639 buffer_clear(&m); 1640 1641 /* Read their reply */ 1642 if (mux_client_read_packet(fd, &m) != 0) { 1643 /* Remote end exited already */ 1644 if (errno == EPIPE) { 1645 buffer_free(&m); 1646 return; 1647 } 1648 fatal("%s: read from master failed: %s", 1649 __func__, strerror(errno)); 1650 } 1651 1652 type = buffer_get_int(&m); 1653 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1654 fatal("%s: out of sequence reply: my id %u theirs %u", 1655 __func__, muxclient_request_id, rid); 1656 switch (type) { 1657 case MUX_S_OK: 1658 break; 1659 case MUX_S_PERMISSION_DENIED: 1660 e = buffer_get_string(&m, NULL); 1661 fatal("Master refused termination request: %s", e); 1662 case MUX_S_FAILURE: 1663 e = buffer_get_string(&m, NULL); 1664 fatal("%s: termination request failed: %s", __func__, e); 1665 default: 1666 fatal("%s: unexpected response from master 0x%08x", 1667 __func__, type); 1668 } 1669 buffer_free(&m); 1670 muxclient_request_id++; 1671} 1672 1673static int 1674mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1675{ 1676 Buffer m; 1677 char *e, *fwd_desc; 1678 u_int type, rid; 1679 1680 fwd_desc = format_forward(ftype, fwd); 1681 debug("Requesting %s %s", 1682 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1683 free(fwd_desc); 1684 1685 buffer_init(&m); 1686 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1687 buffer_put_int(&m, muxclient_request_id); 1688 buffer_put_int(&m, ftype); 1689 if (fwd->listen_path != NULL) { 1690 buffer_put_cstring(&m, fwd->listen_path); 1691 } else { 1692 buffer_put_cstring(&m, 1693 fwd->listen_host == NULL ? "" : fwd->listen_host); 1694 } 1695 buffer_put_int(&m, fwd->listen_port); 1696 if (fwd->connect_path != NULL) { 1697 buffer_put_cstring(&m, fwd->connect_path); 1698 } else { 1699 buffer_put_cstring(&m, 1700 fwd->connect_host == NULL ? "" : fwd->connect_host); 1701 } 1702 buffer_put_int(&m, fwd->connect_port); 1703 1704 if (mux_client_write_packet(fd, &m) != 0) 1705 fatal("%s: write packet: %s", __func__, strerror(errno)); 1706 1707 buffer_clear(&m); 1708 1709 /* Read their reply */ 1710 if (mux_client_read_packet(fd, &m) != 0) { 1711 buffer_free(&m); 1712 return -1; 1713 } 1714 1715 type = buffer_get_int(&m); 1716 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1717 fatal("%s: out of sequence reply: my id %u theirs %u", 1718 __func__, muxclient_request_id, rid); 1719 switch (type) { 1720 case MUX_S_OK: 1721 break; 1722 case MUX_S_REMOTE_PORT: 1723 if (cancel_flag) 1724 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1725 fwd->allocated_port = buffer_get_int(&m); 1726 logit("Allocated port %u for remote forward to %s:%d", 1727 fwd->allocated_port, 1728 fwd->connect_host ? fwd->connect_host : "", 1729 fwd->connect_port); 1730 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1731 fprintf(stdout, "%u\n", fwd->allocated_port); 1732 break; 1733 case MUX_S_PERMISSION_DENIED: 1734 e = buffer_get_string(&m, NULL); 1735 buffer_free(&m); 1736 error("Master refused forwarding request: %s", e); 1737 return -1; 1738 case MUX_S_FAILURE: 1739 e = buffer_get_string(&m, NULL); 1740 buffer_free(&m); 1741 error("%s: forwarding request failed: %s", __func__, e); 1742 return -1; 1743 default: 1744 fatal("%s: unexpected response from master 0x%08x", 1745 __func__, type); 1746 } 1747 buffer_free(&m); 1748 1749 muxclient_request_id++; 1750 return 0; 1751} 1752 1753static int 1754mux_client_forwards(int fd, int cancel_flag) 1755{ 1756 int i, ret = 0; 1757 1758 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1759 cancel_flag ? "cancel" : "request", 1760 options.num_local_forwards, options.num_remote_forwards); 1761 1762 /* XXX ExitOnForwardingFailure */ 1763 for (i = 0; i < options.num_local_forwards; i++) { 1764 if (mux_client_forward(fd, cancel_flag, 1765 options.local_forwards[i].connect_port == 0 ? 1766 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1767 options.local_forwards + i) != 0) 1768 ret = -1; 1769 } 1770 for (i = 0; i < options.num_remote_forwards; i++) { 1771 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1772 options.remote_forwards + i) != 0) 1773 ret = -1; 1774 } 1775 return ret; 1776} 1777 1778static int 1779mux_client_request_session(int fd) 1780{ 1781 Buffer m; 1782 char *e, *term; 1783 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1784 extern char **environ; 1785 int devnull, rawmode; 1786 1787 debug3("%s: entering", __func__); 1788 1789 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1790 error("%s: master alive request failed", __func__); 1791 return -1; 1792 } 1793 1794 signal(SIGPIPE, SIG_IGN); 1795 1796 if (stdin_null_flag) { 1797 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1798 fatal("open(/dev/null): %s", strerror(errno)); 1799 if (dup2(devnull, STDIN_FILENO) == -1) 1800 fatal("dup2: %s", strerror(errno)); 1801 if (devnull > STDERR_FILENO) 1802 close(devnull); 1803 } 1804 1805 term = getenv("TERM"); 1806 1807 buffer_init(&m); 1808 buffer_put_int(&m, MUX_C_NEW_SESSION); 1809 buffer_put_int(&m, muxclient_request_id); 1810 buffer_put_cstring(&m, ""); /* reserved */ 1811 buffer_put_int(&m, tty_flag); 1812 buffer_put_int(&m, options.forward_x11); 1813 buffer_put_int(&m, options.forward_agent); 1814 buffer_put_int(&m, subsystem_flag); 1815 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1816 0xffffffff : (u_int)options.escape_char); 1817 buffer_put_cstring(&m, term == NULL ? "" : term); 1818 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1819 1820 if (options.num_send_env > 0 && environ != NULL) { 1821 /* Pass environment */ 1822 for (i = 0; environ[i] != NULL; i++) { 1823 if (env_permitted(environ[i])) { 1824 buffer_put_cstring(&m, environ[i]); 1825 } 1826 } 1827 } 1828 1829 if (mux_client_write_packet(fd, &m) != 0) 1830 fatal("%s: write packet: %s", __func__, strerror(errno)); 1831 1832 /* Send the stdio file descriptors */ 1833 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1834 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1835 mm_send_fd(fd, STDERR_FILENO) == -1) 1836 fatal("%s: send fds failed", __func__); 1837 1838 debug3("%s: session request sent", __func__); 1839 1840 /* Read their reply */ 1841 buffer_clear(&m); 1842 if (mux_client_read_packet(fd, &m) != 0) { 1843 error("%s: read from master failed: %s", 1844 __func__, strerror(errno)); 1845 buffer_free(&m); 1846 return -1; 1847 } 1848 1849 type = buffer_get_int(&m); 1850 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1851 fatal("%s: out of sequence reply: my id %u theirs %u", 1852 __func__, muxclient_request_id, rid); 1853 switch (type) { 1854 case MUX_S_SESSION_OPENED: 1855 sid = buffer_get_int(&m); 1856 debug("%s: master session id: %u", __func__, sid); 1857 break; 1858 case MUX_S_PERMISSION_DENIED: 1859 e = buffer_get_string(&m, NULL); 1860 buffer_free(&m); 1861 error("Master refused session request: %s", e); 1862 return -1; 1863 case MUX_S_FAILURE: 1864 e = buffer_get_string(&m, NULL); 1865 buffer_free(&m); 1866 error("%s: session request failed: %s", __func__, e); 1867 return -1; 1868 default: 1869 buffer_free(&m); 1870 error("%s: unexpected response from master 0x%08x", 1871 __func__, type); 1872 return -1; 1873 } 1874 muxclient_request_id++; 1875 1876 signal(SIGHUP, control_client_sighandler); 1877 signal(SIGINT, control_client_sighandler); 1878 signal(SIGTERM, control_client_sighandler); 1879 signal(SIGWINCH, control_client_sigrelay); 1880 1881 rawmode = tty_flag; 1882 if (tty_flag) 1883 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1884 1885 /* 1886 * Stick around until the controlee closes the client_fd. 1887 * Before it does, it is expected to write an exit message. 1888 * This process must read the value and wait for the closure of 1889 * the client_fd; if this one closes early, the multiplex master will 1890 * terminate early too (possibly losing data). 1891 */ 1892 for (exitval = 255, exitval_seen = 0;;) { 1893 buffer_clear(&m); 1894 if (mux_client_read_packet(fd, &m) != 0) 1895 break; 1896 type = buffer_get_int(&m); 1897 switch (type) { 1898 case MUX_S_TTY_ALLOC_FAIL: 1899 if ((esid = buffer_get_int(&m)) != sid) 1900 fatal("%s: tty alloc fail on unknown session: " 1901 "my id %u theirs %u", 1902 __func__, sid, esid); 1903 leave_raw_mode(options.request_tty == 1904 REQUEST_TTY_FORCE); 1905 rawmode = 0; 1906 continue; 1907 case MUX_S_EXIT_MESSAGE: 1908 if ((esid = buffer_get_int(&m)) != sid) 1909 fatal("%s: exit on unknown session: " 1910 "my id %u theirs %u", 1911 __func__, sid, esid); 1912 if (exitval_seen) 1913 fatal("%s: exitval sent twice", __func__); 1914 exitval = buffer_get_int(&m); 1915 exitval_seen = 1; 1916 continue; 1917 default: 1918 e = buffer_get_string(&m, NULL); 1919 fatal("%s: master returned error: %s", __func__, e); 1920 } 1921 } 1922 1923 close(fd); 1924 if (rawmode) 1925 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1926 1927 if (muxclient_terminate) { 1928 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1929 exitval = 255; 1930 } else if (!exitval_seen) { 1931 debug2("Control master terminated unexpectedly"); 1932 exitval = 255; 1933 } else 1934 debug2("Received exit status from master %d", exitval); 1935 1936 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1937 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1938 1939 exit(exitval); 1940} 1941 1942static int 1943mux_client_request_stdio_fwd(int fd) 1944{ 1945 Buffer m; 1946 char *e; 1947 u_int type, rid, sid; 1948 int devnull; 1949 1950 debug3("%s: entering", __func__); 1951 1952 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1953 error("%s: master alive request failed", __func__); 1954 return -1; 1955 } 1956 1957 signal(SIGPIPE, SIG_IGN); 1958 1959 if (stdin_null_flag) { 1960 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1961 fatal("open(/dev/null): %s", strerror(errno)); 1962 if (dup2(devnull, STDIN_FILENO) == -1) 1963 fatal("dup2: %s", strerror(errno)); 1964 if (devnull > STDERR_FILENO) 1965 close(devnull); 1966 } 1967 1968 buffer_init(&m); 1969 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1970 buffer_put_int(&m, muxclient_request_id); 1971 buffer_put_cstring(&m, ""); /* reserved */ 1972 buffer_put_cstring(&m, stdio_forward_host); 1973 buffer_put_int(&m, stdio_forward_port); 1974 1975 if (mux_client_write_packet(fd, &m) != 0) 1976 fatal("%s: write packet: %s", __func__, strerror(errno)); 1977 1978 /* Send the stdio file descriptors */ 1979 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1980 mm_send_fd(fd, STDOUT_FILENO) == -1) 1981 fatal("%s: send fds failed", __func__); 1982 1983 debug3("%s: stdio forward request sent", __func__); 1984 1985 /* Read their reply */ 1986 buffer_clear(&m); 1987 1988 if (mux_client_read_packet(fd, &m) != 0) { 1989 error("%s: read from master failed: %s", 1990 __func__, strerror(errno)); 1991 buffer_free(&m); 1992 return -1; 1993 } 1994 1995 type = buffer_get_int(&m); 1996 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1997 fatal("%s: out of sequence reply: my id %u theirs %u", 1998 __func__, muxclient_request_id, rid); 1999 switch (type) { 2000 case MUX_S_SESSION_OPENED: 2001 sid = buffer_get_int(&m); 2002 debug("%s: master session id: %u", __func__, sid); 2003 break; 2004 case MUX_S_PERMISSION_DENIED: 2005 e = buffer_get_string(&m, NULL); 2006 buffer_free(&m); 2007 fatal("Master refused stdio forwarding request: %s", e); 2008 case MUX_S_FAILURE: 2009 e = buffer_get_string(&m, NULL); 2010 buffer_free(&m); 2011 fatal("Stdio forwarding request failed: %s", e); 2012 default: 2013 buffer_free(&m); 2014 error("%s: unexpected response from master 0x%08x", 2015 __func__, type); 2016 return -1; 2017 } 2018 muxclient_request_id++; 2019 2020 signal(SIGHUP, control_client_sighandler); 2021 signal(SIGINT, control_client_sighandler); 2022 signal(SIGTERM, control_client_sighandler); 2023 signal(SIGWINCH, control_client_sigrelay); 2024 2025 /* 2026 * Stick around until the controlee closes the client_fd. 2027 */ 2028 buffer_clear(&m); 2029 if (mux_client_read_packet(fd, &m) != 0) { 2030 if (errno == EPIPE || 2031 (errno == EINTR && muxclient_terminate != 0)) 2032 return 0; 2033 fatal("%s: mux_client_read_packet: %s", 2034 __func__, strerror(errno)); 2035 } 2036 fatal("%s: master returned unexpected message %u", __func__, type); 2037} 2038 2039static void 2040mux_client_request_stop_listening(int fd) 2041{ 2042 Buffer m; 2043 char *e; 2044 u_int type, rid; 2045 2046 debug3("%s: entering", __func__); 2047 2048 buffer_init(&m); 2049 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2050 buffer_put_int(&m, muxclient_request_id); 2051 2052 if (mux_client_write_packet(fd, &m) != 0) 2053 fatal("%s: write packet: %s", __func__, strerror(errno)); 2054 2055 buffer_clear(&m); 2056 2057 /* Read their reply */ 2058 if (mux_client_read_packet(fd, &m) != 0) 2059 fatal("%s: read from master failed: %s", 2060 __func__, strerror(errno)); 2061 2062 type = buffer_get_int(&m); 2063 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2064 fatal("%s: out of sequence reply: my id %u theirs %u", 2065 __func__, muxclient_request_id, rid); 2066 switch (type) { 2067 case MUX_S_OK: 2068 break; 2069 case MUX_S_PERMISSION_DENIED: 2070 e = buffer_get_string(&m, NULL); 2071 fatal("Master refused stop listening request: %s", e); 2072 case MUX_S_FAILURE: 2073 e = buffer_get_string(&m, NULL); 2074 fatal("%s: stop listening request failed: %s", __func__, e); 2075 default: 2076 fatal("%s: unexpected response from master 0x%08x", 2077 __func__, type); 2078 } 2079 buffer_free(&m); 2080 muxclient_request_id++; 2081} 2082 2083/* Multiplex client main loop. */ 2084void 2085muxclient(const char *path) 2086{ 2087 struct sockaddr_un addr; 2088 socklen_t sun_len; 2089 int sock; 2090 u_int pid; 2091 2092 if (muxclient_command == 0) { 2093 if (stdio_forward_host != NULL) 2094 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2095 else 2096 muxclient_command = SSHMUX_COMMAND_OPEN; 2097 } 2098 2099 switch (options.control_master) { 2100 case SSHCTL_MASTER_AUTO: 2101 case SSHCTL_MASTER_AUTO_ASK: 2102 debug("auto-mux: Trying existing master"); 2103 /* FALLTHROUGH */ 2104 case SSHCTL_MASTER_NO: 2105 break; 2106 default: 2107 return; 2108 } 2109 2110 memset(&addr, '\0', sizeof(addr)); 2111 addr.sun_family = AF_UNIX; 2112 sun_len = offsetof(struct sockaddr_un, sun_path) + 2113 strlen(path) + 1; 2114 2115 if (strlcpy(addr.sun_path, path, 2116 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2117 fatal("ControlPath too long"); 2118 2119 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2120 fatal("%s socket(): %s", __func__, strerror(errno)); 2121 2122 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2123 switch (muxclient_command) { 2124 case SSHMUX_COMMAND_OPEN: 2125 case SSHMUX_COMMAND_STDIO_FWD: 2126 break; 2127 default: 2128 fatal("Control socket connect(%.100s): %s", path, 2129 strerror(errno)); 2130 } 2131 if (errno == ECONNREFUSED && 2132 options.control_master != SSHCTL_MASTER_NO) { 2133 debug("Stale control socket %.100s, unlinking", path); 2134 unlink(path); 2135 } else if (errno == ENOENT) { 2136 debug("Control socket \"%.100s\" does not exist", path); 2137 } else { 2138 error("Control socket connect(%.100s): %s", path, 2139 strerror(errno)); 2140 } 2141 close(sock); 2142 return; 2143 } 2144 set_nonblock(sock); 2145 2146 if (mux_client_hello_exchange(sock) != 0) { 2147 error("%s: master hello exchange failed", __func__); 2148 close(sock); 2149 return; 2150 } 2151 2152 switch (muxclient_command) { 2153 case SSHMUX_COMMAND_ALIVE_CHECK: 2154 if ((pid = mux_client_request_alive(sock)) == 0) 2155 fatal("%s: master alive check failed", __func__); 2156 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2157 exit(0); 2158 case SSHMUX_COMMAND_TERMINATE: 2159 mux_client_request_terminate(sock); 2160 fprintf(stderr, "Exit request sent.\r\n"); 2161 exit(0); 2162 case SSHMUX_COMMAND_FORWARD: 2163 if (mux_client_forwards(sock, 0) != 0) 2164 fatal("%s: master forward request failed", __func__); 2165 exit(0); 2166 case SSHMUX_COMMAND_OPEN: 2167 if (mux_client_forwards(sock, 0) != 0) { 2168 error("%s: master forward request failed", __func__); 2169 return; 2170 } 2171 mux_client_request_session(sock); 2172 return; 2173 case SSHMUX_COMMAND_STDIO_FWD: 2174 mux_client_request_stdio_fwd(sock); 2175 exit(0); 2176 case SSHMUX_COMMAND_STOP: 2177 mux_client_request_stop_listening(sock); 2178 fprintf(stderr, "Stop listening request sent.\r\n"); 2179 exit(0); 2180 case SSHMUX_COMMAND_CANCEL_FWD: 2181 if (mux_client_forwards(sock, 1) != 0) 2182 error("%s: master cancel forward request failed", 2183 __func__); 2184 exit(0); 2185 default: 2186 fatal("unrecognised muxclient_command %d", muxclient_command); 2187 } 2188} 2189