mux.c revision 323129
1/* $OpenBSD: mux.c,v 1.60 2016/06/03 03:14:41 dtucker 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/11/crypto/openssh/mux.c 323129 2017-09-02 14:25:20Z 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; 92 93/* Context for session open confirmation callback */ 94struct mux_session_confirm_ctx { 95 u_int want_tty; 96 u_int want_subsys; 97 u_int want_x_fwd; 98 u_int want_agent_fwd; 99 Buffer cmd; 100 char *term; 101 struct termios tio; 102 char **env; 103 u_int rid; 104}; 105 106/* Context for stdio fwd open confirmation callback */ 107struct mux_stdio_confirm_ctx { 108 u_int rid; 109}; 110 111/* Context for global channel callback */ 112struct mux_channel_confirm_ctx { 113 u_int cid; /* channel id */ 114 u_int rid; /* request id */ 115 int fid; /* forward id */ 116}; 117 118/* fd to control socket */ 119int muxserver_sock = -1; 120 121/* client request id */ 122u_int muxclient_request_id = 0; 123 124/* Multiplexing control command */ 125u_int muxclient_command = 0; 126 127/* Set when signalled. */ 128static volatile sig_atomic_t muxclient_terminate = 0; 129 130/* PID of multiplex server */ 131static u_int muxserver_pid = 0; 132 133static Channel *mux_listener_channel = NULL; 134 135struct mux_master_state { 136 int hello_rcvd; 137}; 138 139/* mux protocol messages */ 140#define MUX_MSG_HELLO 0x00000001 141#define MUX_C_NEW_SESSION 0x10000002 142#define MUX_C_ALIVE_CHECK 0x10000004 143#define MUX_C_TERMINATE 0x10000005 144#define MUX_C_OPEN_FWD 0x10000006 145#define MUX_C_CLOSE_FWD 0x10000007 146#define MUX_C_NEW_STDIO_FWD 0x10000008 147#define MUX_C_STOP_LISTENING 0x10000009 148#define MUX_S_OK 0x80000001 149#define MUX_S_PERMISSION_DENIED 0x80000002 150#define MUX_S_FAILURE 0x80000003 151#define MUX_S_EXIT_MESSAGE 0x80000004 152#define MUX_S_ALIVE 0x80000005 153#define MUX_S_SESSION_OPENED 0x80000006 154#define MUX_S_REMOTE_PORT 0x80000007 155#define MUX_S_TTY_ALLOC_FAIL 0x80000008 156 157/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 158#define MUX_FWD_LOCAL 1 159#define MUX_FWD_REMOTE 2 160#define MUX_FWD_DYNAMIC 3 161 162static void mux_session_confirm(int, int, void *); 163static void mux_stdio_confirm(int, int, void *); 164 165static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 166static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 167static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 168static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 169static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 170static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 171static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 172static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 173 174static const struct { 175 u_int type; 176 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 177} mux_master_handlers[] = { 178 { MUX_MSG_HELLO, process_mux_master_hello }, 179 { MUX_C_NEW_SESSION, process_mux_new_session }, 180 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 181 { MUX_C_TERMINATE, process_mux_terminate }, 182 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 183 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 184 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 185 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 186 { 0, NULL } 187}; 188 189/* Cleanup callback fired on closure of mux slave _session_ channel */ 190/* ARGSUSED */ 191static void 192mux_master_session_cleanup_cb(int cid, void *unused) 193{ 194 Channel *cc, *c = channel_by_id(cid); 195 196 debug3("%s: entering for channel %d", __func__, cid); 197 if (c == NULL) 198 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 199 if (c->ctl_chan != -1) { 200 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 201 fatal("%s: channel %d missing control channel %d", 202 __func__, c->self, c->ctl_chan); 203 c->ctl_chan = -1; 204 cc->remote_id = -1; 205 chan_rcvd_oclose(cc); 206 } 207 channel_cancel_cleanup(c->self); 208} 209 210/* Cleanup callback fired on closure of mux slave _control_ channel */ 211/* ARGSUSED */ 212static void 213mux_master_control_cleanup_cb(int cid, void *unused) 214{ 215 Channel *sc, *c = channel_by_id(cid); 216 217 debug3("%s: entering for channel %d", __func__, cid); 218 if (c == NULL) 219 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 220 if (c->remote_id != -1) { 221 if ((sc = channel_by_id(c->remote_id)) == NULL) 222 fatal("%s: channel %d missing session channel %d", 223 __func__, c->self, c->remote_id); 224 c->remote_id = -1; 225 sc->ctl_chan = -1; 226 if (sc->type != SSH_CHANNEL_OPEN && 227 sc->type != SSH_CHANNEL_OPENING) { 228 debug2("%s: channel %d: not open", __func__, sc->self); 229 chan_mark_dead(sc); 230 } else { 231 if (sc->istate == CHAN_INPUT_OPEN) 232 chan_read_failed(sc); 233 if (sc->ostate == CHAN_OUTPUT_OPEN) 234 chan_write_failed(sc); 235 } 236 } 237 channel_cancel_cleanup(c->self); 238} 239 240/* Check mux client environment variables before passing them to mux master. */ 241static int 242env_permitted(char *env) 243{ 244 int i, ret; 245 char name[1024], *cp; 246 247 if ((cp = strchr(env, '=')) == NULL || cp == env) 248 return 0; 249 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 250 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 251 error("env_permitted: name '%.100s...' too long", env); 252 return 0; 253 } 254 255 for (i = 0; i < options.num_send_env; i++) 256 if (match_pattern(name, options.send_env[i])) 257 return 1; 258 259 return 0; 260} 261 262/* Mux master protocol message handlers */ 263 264static int 265process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 266{ 267 u_int ver; 268 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 269 270 if (state == NULL) 271 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 272 if (state->hello_rcvd) { 273 error("%s: HELLO received twice", __func__); 274 return -1; 275 } 276 if (buffer_get_int_ret(&ver, m) != 0) { 277 malf: 278 error("%s: malformed message", __func__); 279 return -1; 280 } 281 if (ver != SSHMUX_VER) { 282 error("Unsupported multiplexing protocol version %d " 283 "(expected %d)", ver, SSHMUX_VER); 284 return -1; 285 } 286 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 287 288 /* No extensions are presently defined */ 289 while (buffer_len(m) > 0) { 290 char *name = buffer_get_string_ret(m, NULL); 291 char *value = buffer_get_string_ret(m, NULL); 292 293 if (name == NULL || value == NULL) { 294 free(name); 295 free(value); 296 goto malf; 297 } 298 debug2("Unrecognised slave extension \"%s\"", name); 299 free(name); 300 free(value); 301 } 302 state->hello_rcvd = 1; 303 return 0; 304} 305 306static int 307process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 308{ 309 Channel *nc; 310 struct mux_session_confirm_ctx *cctx; 311 char *reserved, *cmd, *cp; 312 u_int i, j, len, env_len, escape_char, window, packetmax; 313 int new_fd[3]; 314 315 /* Reply for SSHMUX_COMMAND_OPEN */ 316 cctx = xcalloc(1, sizeof(*cctx)); 317 cctx->term = NULL; 318 cctx->rid = rid; 319 cmd = reserved = NULL; 320 cctx->env = NULL; 321 env_len = 0; 322 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 323 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 324 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 325 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 326 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 327 buffer_get_int_ret(&escape_char, m) != 0 || 328 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 329 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 330 malf: 331 free(cmd); 332 free(reserved); 333 for (j = 0; j < env_len; j++) 334 free(cctx->env[j]); 335 free(cctx->env); 336 free(cctx->term); 337 free(cctx); 338 error("%s: malformed message", __func__); 339 return -1; 340 } 341 free(reserved); 342 reserved = NULL; 343 344 while (buffer_len(m) > 0) { 345#define MUX_MAX_ENV_VARS 4096 346 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 347 goto malf; 348 if (!env_permitted(cp)) { 349 free(cp); 350 continue; 351 } 352 cctx->env = xreallocarray(cctx->env, env_len + 2, 353 sizeof(*cctx->env)); 354 cctx->env[env_len++] = cp; 355 cctx->env[env_len] = NULL; 356 if (env_len > MUX_MAX_ENV_VARS) { 357 error(">%d environment variables received, ignoring " 358 "additional", MUX_MAX_ENV_VARS); 359 break; 360 } 361 } 362 363 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 364 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 365 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 366 cctx->want_subsys, cctx->term, cmd, env_len); 367 368 buffer_init(&cctx->cmd); 369 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 370 free(cmd); 371 cmd = NULL; 372 373 /* Gather fds from client */ 374 for(i = 0; i < 3; i++) { 375 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 376 error("%s: failed to receive fd %d from slave", 377 __func__, i); 378 for (j = 0; j < i; j++) 379 close(new_fd[j]); 380 for (j = 0; j < env_len; j++) 381 free(cctx->env[j]); 382 free(cctx->env); 383 free(cctx->term); 384 buffer_free(&cctx->cmd); 385 free(cctx); 386 387 /* prepare reply */ 388 buffer_put_int(r, MUX_S_FAILURE); 389 buffer_put_int(r, rid); 390 buffer_put_cstring(r, 391 "did not receive file descriptors"); 392 return -1; 393 } 394 } 395 396 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 397 new_fd[0], new_fd[1], new_fd[2]); 398 399 /* XXX support multiple child sessions in future */ 400 if (c->remote_id != -1) { 401 debug2("%s: session already open", __func__); 402 /* prepare reply */ 403 buffer_put_int(r, MUX_S_FAILURE); 404 buffer_put_int(r, rid); 405 buffer_put_cstring(r, "Multiple sessions not supported"); 406 cleanup: 407 close(new_fd[0]); 408 close(new_fd[1]); 409 close(new_fd[2]); 410 free(cctx->term); 411 if (env_len != 0) { 412 for (i = 0; i < env_len; i++) 413 free(cctx->env[i]); 414 free(cctx->env); 415 } 416 buffer_free(&cctx->cmd); 417 free(cctx); 418 return 0; 419 } 420 421 if (options.control_master == SSHCTL_MASTER_ASK || 422 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 423 if (!ask_permission("Allow shared connection to %s? ", host)) { 424 debug2("%s: session refused by user", __func__); 425 /* prepare reply */ 426 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 427 buffer_put_int(r, rid); 428 buffer_put_cstring(r, "Permission denied"); 429 goto cleanup; 430 } 431 } 432 433 /* Try to pick up ttymodes from client before it goes raw */ 434 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 435 error("%s: tcgetattr: %s", __func__, strerror(errno)); 436 437 /* enable nonblocking unless tty */ 438 if (!isatty(new_fd[0])) 439 set_nonblock(new_fd[0]); 440 if (!isatty(new_fd[1])) 441 set_nonblock(new_fd[1]); 442 if (!isatty(new_fd[2])) 443 set_nonblock(new_fd[2]); 444 445 window = CHAN_SES_WINDOW_DEFAULT; 446 packetmax = CHAN_SES_PACKET_DEFAULT; 447 if (cctx->want_tty) { 448 window >>= 1; 449 packetmax >>= 1; 450 } 451 452 nc = channel_new("session", SSH_CHANNEL_OPENING, 453 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 454 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 455 456 nc->ctl_chan = c->self; /* link session -> control channel */ 457 c->remote_id = nc->self; /* link control -> session channel */ 458 459 if (cctx->want_tty && escape_char != 0xffffffff) { 460 channel_register_filter(nc->self, 461 client_simple_escape_filter, NULL, 462 client_filter_cleanup, 463 client_new_escape_filter_ctx((int)escape_char)); 464 } 465 466 debug2("%s: channel_new: %d linked to control channel %d", 467 __func__, nc->self, nc->ctl_chan); 468 469 channel_send_open(nc->self); 470 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 471 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 472 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 473 474 /* reply is deferred, sent by mux_session_confirm */ 475 return 0; 476} 477 478static int 479process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 480{ 481 debug2("%s: channel %d: alive check", __func__, c->self); 482 483 /* prepare reply */ 484 buffer_put_int(r, MUX_S_ALIVE); 485 buffer_put_int(r, rid); 486 buffer_put_int(r, (u_int)getpid()); 487 488 return 0; 489} 490 491static int 492process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 493{ 494 debug2("%s: channel %d: terminate request", __func__, c->self); 495 496 if (options.control_master == SSHCTL_MASTER_ASK || 497 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 498 if (!ask_permission("Terminate shared connection to %s? ", 499 host)) { 500 debug2("%s: termination refused by user", __func__); 501 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 502 buffer_put_int(r, rid); 503 buffer_put_cstring(r, "Permission denied"); 504 return 0; 505 } 506 } 507 508 quit_pending = 1; 509 buffer_put_int(r, MUX_S_OK); 510 buffer_put_int(r, rid); 511 /* XXX exit happens too soon - message never makes it to client */ 512 return 0; 513} 514 515static char * 516format_forward(u_int ftype, struct Forward *fwd) 517{ 518 char *ret; 519 520 switch (ftype) { 521 case MUX_FWD_LOCAL: 522 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 523 (fwd->listen_path != NULL) ? fwd->listen_path : 524 (fwd->listen_host == NULL) ? 525 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 526 fwd->listen_host, fwd->listen_port, 527 (fwd->connect_path != NULL) ? fwd->connect_path : 528 fwd->connect_host, fwd->connect_port); 529 break; 530 case MUX_FWD_DYNAMIC: 531 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 532 (fwd->listen_host == NULL) ? 533 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 534 fwd->listen_host, fwd->listen_port); 535 break; 536 case MUX_FWD_REMOTE: 537 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 538 (fwd->listen_path != NULL) ? fwd->listen_path : 539 (fwd->listen_host == NULL) ? 540 "LOCALHOST" : fwd->listen_host, 541 fwd->listen_port, 542 (fwd->connect_path != NULL) ? fwd->connect_path : 543 fwd->connect_host, fwd->connect_port); 544 break; 545 default: 546 fatal("%s: unknown forward type %u", __func__, ftype); 547 } 548 return ret; 549} 550 551static int 552compare_host(const char *a, const char *b) 553{ 554 if (a == NULL && b == NULL) 555 return 1; 556 if (a == NULL || b == NULL) 557 return 0; 558 return strcmp(a, b) == 0; 559} 560 561static int 562compare_forward(struct Forward *a, struct Forward *b) 563{ 564 if (!compare_host(a->listen_host, b->listen_host)) 565 return 0; 566 if (!compare_host(a->listen_path, b->listen_path)) 567 return 0; 568 if (a->listen_port != b->listen_port) 569 return 0; 570 if (!compare_host(a->connect_host, b->connect_host)) 571 return 0; 572 if (!compare_host(a->connect_path, b->connect_path)) 573 return 0; 574 if (a->connect_port != b->connect_port) 575 return 0; 576 577 return 1; 578} 579 580static void 581mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 582{ 583 struct mux_channel_confirm_ctx *fctx = ctxt; 584 char *failmsg = NULL; 585 struct Forward *rfwd; 586 Channel *c; 587 Buffer out; 588 589 if ((c = channel_by_id(fctx->cid)) == NULL) { 590 /* no channel for reply */ 591 error("%s: unknown channel", __func__); 592 return; 593 } 594 buffer_init(&out); 595 if (fctx->fid >= options.num_remote_forwards || 596 (options.remote_forwards[fctx->fid].connect_path == NULL && 597 options.remote_forwards[fctx->fid].connect_host == NULL)) { 598 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 599 goto fail; 600 } 601 rfwd = &options.remote_forwards[fctx->fid]; 602 debug("%s: %s for: listen %d, connect %s:%d", __func__, 603 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 604 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 605 rfwd->connect_host, rfwd->connect_port); 606 if (type == SSH2_MSG_REQUEST_SUCCESS) { 607 if (rfwd->listen_port == 0) { 608 rfwd->allocated_port = packet_get_int(); 609 debug("Allocated port %u for mux remote forward" 610 " to %s:%d", rfwd->allocated_port, 611 rfwd->connect_host, rfwd->connect_port); 612 buffer_put_int(&out, MUX_S_REMOTE_PORT); 613 buffer_put_int(&out, fctx->rid); 614 buffer_put_int(&out, rfwd->allocated_port); 615 channel_update_permitted_opens(rfwd->handle, 616 rfwd->allocated_port); 617 } else { 618 buffer_put_int(&out, MUX_S_OK); 619 buffer_put_int(&out, fctx->rid); 620 } 621 goto out; 622 } else { 623 if (rfwd->listen_port == 0) 624 channel_update_permitted_opens(rfwd->handle, -1); 625 if (rfwd->listen_path != NULL) 626 xasprintf(&failmsg, "remote port forwarding failed for " 627 "listen path %s", rfwd->listen_path); 628 else 629 xasprintf(&failmsg, "remote port forwarding failed for " 630 "listen port %d", rfwd->listen_port); 631 632 debug2("%s: clearing registered forwarding for listen %d, " 633 "connect %s:%d", __func__, rfwd->listen_port, 634 rfwd->connect_path ? rfwd->connect_path : 635 rfwd->connect_host, rfwd->connect_port); 636 637 free(rfwd->listen_host); 638 free(rfwd->listen_path); 639 free(rfwd->connect_host); 640 free(rfwd->connect_path); 641 memset(rfwd, 0, sizeof(*rfwd)); 642 } 643 fail: 644 error("%s: %s", __func__, failmsg); 645 buffer_put_int(&out, MUX_S_FAILURE); 646 buffer_put_int(&out, fctx->rid); 647 buffer_put_cstring(&out, failmsg); 648 free(failmsg); 649 out: 650 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 651 buffer_free(&out); 652 if (c->mux_pause <= 0) 653 fatal("%s: mux_pause %d", __func__, c->mux_pause); 654 c->mux_pause = 0; /* start processing messages again */ 655} 656 657static int 658process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 659{ 660 struct Forward fwd; 661 char *fwd_desc = NULL; 662 char *listen_addr, *connect_addr; 663 u_int ftype; 664 u_int lport, cport; 665 int i, ret = 0, freefwd = 1; 666 667 memset(&fwd, 0, sizeof(fwd)); 668 669 /* XXX - lport/cport check redundant */ 670 if (buffer_get_int_ret(&ftype, m) != 0 || 671 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 672 buffer_get_int_ret(&lport, m) != 0 || 673 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 674 buffer_get_int_ret(&cport, m) != 0 || 675 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 676 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 677 error("%s: malformed message", __func__); 678 ret = -1; 679 goto out; 680 } 681 if (*listen_addr == '\0') { 682 free(listen_addr); 683 listen_addr = NULL; 684 } 685 if (*connect_addr == '\0') { 686 free(connect_addr); 687 connect_addr = NULL; 688 } 689 690 memset(&fwd, 0, sizeof(fwd)); 691 fwd.listen_port = lport; 692 if (fwd.listen_port == PORT_STREAMLOCAL) 693 fwd.listen_path = listen_addr; 694 else 695 fwd.listen_host = listen_addr; 696 fwd.connect_port = cport; 697 if (fwd.connect_port == PORT_STREAMLOCAL) 698 fwd.connect_path = connect_addr; 699 else 700 fwd.connect_host = connect_addr; 701 702 debug2("%s: channel %d: request %s", __func__, c->self, 703 (fwd_desc = format_forward(ftype, &fwd))); 704 705 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 706 ftype != MUX_FWD_DYNAMIC) { 707 logit("%s: invalid forwarding type %u", __func__, ftype); 708 invalid: 709 free(listen_addr); 710 free(connect_addr); 711 buffer_put_int(r, MUX_S_FAILURE); 712 buffer_put_int(r, rid); 713 buffer_put_cstring(r, "Invalid forwarding request"); 714 return 0; 715 } 716 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 717 logit("%s: streamlocal and dynamic forwards " 718 "are mutually exclusive", __func__); 719 goto invalid; 720 } 721 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 722 logit("%s: invalid listen port %u", __func__, 723 fwd.listen_port); 724 goto invalid; 725 } 726 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 727 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 728 logit("%s: invalid connect port %u", __func__, 729 fwd.connect_port); 730 goto invalid; 731 } 732 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 733 logit("%s: missing connect host", __func__); 734 goto invalid; 735 } 736 737 /* Skip forwards that have already been requested */ 738 switch (ftype) { 739 case MUX_FWD_LOCAL: 740 case MUX_FWD_DYNAMIC: 741 for (i = 0; i < options.num_local_forwards; i++) { 742 if (compare_forward(&fwd, 743 options.local_forwards + i)) { 744 exists: 745 debug2("%s: found existing forwarding", 746 __func__); 747 buffer_put_int(r, MUX_S_OK); 748 buffer_put_int(r, rid); 749 goto out; 750 } 751 } 752 break; 753 case MUX_FWD_REMOTE: 754 for (i = 0; i < options.num_remote_forwards; i++) { 755 if (compare_forward(&fwd, 756 options.remote_forwards + i)) { 757 if (fwd.listen_port != 0) 758 goto exists; 759 debug2("%s: found allocated port", 760 __func__); 761 buffer_put_int(r, MUX_S_REMOTE_PORT); 762 buffer_put_int(r, rid); 763 buffer_put_int(r, 764 options.remote_forwards[i].allocated_port); 765 goto out; 766 } 767 } 768 break; 769 } 770 771 if (options.control_master == SSHCTL_MASTER_ASK || 772 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 773 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 774 debug2("%s: forwarding refused by user", __func__); 775 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 776 buffer_put_int(r, rid); 777 buffer_put_cstring(r, "Permission denied"); 778 goto out; 779 } 780 } 781 782 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 783 if (!channel_setup_local_fwd_listener(&fwd, 784 &options.fwd_opts)) { 785 fail: 786 logit("slave-requested %s failed", fwd_desc); 787 buffer_put_int(r, MUX_S_FAILURE); 788 buffer_put_int(r, rid); 789 buffer_put_cstring(r, "Port forwarding failed"); 790 goto out; 791 } 792 add_local_forward(&options, &fwd); 793 freefwd = 0; 794 } else { 795 struct mux_channel_confirm_ctx *fctx; 796 797 fwd.handle = channel_request_remote_forwarding(&fwd); 798 if (fwd.handle < 0) 799 goto fail; 800 add_remote_forward(&options, &fwd); 801 fctx = xcalloc(1, sizeof(*fctx)); 802 fctx->cid = c->self; 803 fctx->rid = rid; 804 fctx->fid = options.num_remote_forwards - 1; 805 client_register_global_confirm(mux_confirm_remote_forward, 806 fctx); 807 freefwd = 0; 808 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 809 /* delayed reply in mux_confirm_remote_forward */ 810 goto out; 811 } 812 buffer_put_int(r, MUX_S_OK); 813 buffer_put_int(r, rid); 814 out: 815 free(fwd_desc); 816 if (freefwd) { 817 free(fwd.listen_host); 818 free(fwd.listen_path); 819 free(fwd.connect_host); 820 free(fwd.connect_path); 821 } 822 return ret; 823} 824 825static int 826process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 827{ 828 struct Forward fwd, *found_fwd; 829 char *fwd_desc = NULL; 830 const char *error_reason = NULL; 831 char *listen_addr = NULL, *connect_addr = NULL; 832 u_int ftype; 833 int i, ret = 0; 834 u_int lport, cport; 835 836 memset(&fwd, 0, sizeof(fwd)); 837 838 if (buffer_get_int_ret(&ftype, m) != 0 || 839 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 840 buffer_get_int_ret(&lport, m) != 0 || 841 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 842 buffer_get_int_ret(&cport, m) != 0 || 843 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 844 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 845 error("%s: malformed message", __func__); 846 ret = -1; 847 goto out; 848 } 849 850 if (*listen_addr == '\0') { 851 free(listen_addr); 852 listen_addr = NULL; 853 } 854 if (*connect_addr == '\0') { 855 free(connect_addr); 856 connect_addr = NULL; 857 } 858 859 memset(&fwd, 0, sizeof(fwd)); 860 fwd.listen_port = lport; 861 if (fwd.listen_port == PORT_STREAMLOCAL) 862 fwd.listen_path = listen_addr; 863 else 864 fwd.listen_host = listen_addr; 865 fwd.connect_port = cport; 866 if (fwd.connect_port == PORT_STREAMLOCAL) 867 fwd.connect_path = connect_addr; 868 else 869 fwd.connect_host = connect_addr; 870 871 debug2("%s: channel %d: request cancel %s", __func__, c->self, 872 (fwd_desc = format_forward(ftype, &fwd))); 873 874 /* make sure this has been requested */ 875 found_fwd = NULL; 876 switch (ftype) { 877 case MUX_FWD_LOCAL: 878 case MUX_FWD_DYNAMIC: 879 for (i = 0; i < options.num_local_forwards; i++) { 880 if (compare_forward(&fwd, 881 options.local_forwards + i)) { 882 found_fwd = options.local_forwards + i; 883 break; 884 } 885 } 886 break; 887 case MUX_FWD_REMOTE: 888 for (i = 0; i < options.num_remote_forwards; i++) { 889 if (compare_forward(&fwd, 890 options.remote_forwards + i)) { 891 found_fwd = options.remote_forwards + i; 892 break; 893 } 894 } 895 break; 896 } 897 898 if (found_fwd == NULL) 899 error_reason = "port not forwarded"; 900 else if (ftype == MUX_FWD_REMOTE) { 901 /* 902 * This shouldn't fail unless we confused the host/port 903 * between options.remote_forwards and permitted_opens. 904 * However, for dynamic allocated listen ports we need 905 * to use the actual listen port. 906 */ 907 if (channel_request_rforward_cancel(found_fwd) == -1) 908 error_reason = "port not in permitted opens"; 909 } else { /* local and dynamic forwards */ 910 /* Ditto */ 911 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 912 &options.fwd_opts) == -1) 913 error_reason = "port not found"; 914 } 915 916 if (error_reason == NULL) { 917 buffer_put_int(r, MUX_S_OK); 918 buffer_put_int(r, rid); 919 920 free(found_fwd->listen_host); 921 free(found_fwd->listen_path); 922 free(found_fwd->connect_host); 923 free(found_fwd->connect_path); 924 found_fwd->listen_host = found_fwd->connect_host = NULL; 925 found_fwd->listen_path = found_fwd->connect_path = NULL; 926 found_fwd->listen_port = found_fwd->connect_port = 0; 927 } else { 928 buffer_put_int(r, MUX_S_FAILURE); 929 buffer_put_int(r, rid); 930 buffer_put_cstring(r, error_reason); 931 } 932 out: 933 free(fwd_desc); 934 free(listen_addr); 935 free(connect_addr); 936 937 return ret; 938} 939 940static int 941process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 942{ 943 Channel *nc; 944 char *reserved, *chost; 945 u_int cport, i, j; 946 int new_fd[2]; 947 struct mux_stdio_confirm_ctx *cctx; 948 949 chost = reserved = NULL; 950 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 951 (chost = buffer_get_string_ret(m, NULL)) == NULL || 952 buffer_get_int_ret(&cport, m) != 0) { 953 free(reserved); 954 free(chost); 955 error("%s: malformed message", __func__); 956 return -1; 957 } 958 free(reserved); 959 960 debug2("%s: channel %d: request stdio fwd to %s:%u", 961 __func__, c->self, chost, cport); 962 963 /* Gather fds from client */ 964 for(i = 0; i < 2; i++) { 965 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 966 error("%s: failed to receive fd %d from slave", 967 __func__, i); 968 for (j = 0; j < i; j++) 969 close(new_fd[j]); 970 free(chost); 971 972 /* prepare reply */ 973 buffer_put_int(r, MUX_S_FAILURE); 974 buffer_put_int(r, rid); 975 buffer_put_cstring(r, 976 "did not receive file descriptors"); 977 return -1; 978 } 979 } 980 981 debug3("%s: got fds stdin %d, stdout %d", __func__, 982 new_fd[0], new_fd[1]); 983 984 /* XXX support multiple child sessions in future */ 985 if (c->remote_id != -1) { 986 debug2("%s: session already open", __func__); 987 /* prepare reply */ 988 buffer_put_int(r, MUX_S_FAILURE); 989 buffer_put_int(r, rid); 990 buffer_put_cstring(r, "Multiple sessions not supported"); 991 cleanup: 992 close(new_fd[0]); 993 close(new_fd[1]); 994 free(chost); 995 return 0; 996 } 997 998 if (options.control_master == SSHCTL_MASTER_ASK || 999 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1000 if (!ask_permission("Allow forward to %s:%u? ", 1001 chost, cport)) { 1002 debug2("%s: stdio fwd refused by user", __func__); 1003 /* prepare reply */ 1004 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1005 buffer_put_int(r, rid); 1006 buffer_put_cstring(r, "Permission denied"); 1007 goto cleanup; 1008 } 1009 } 1010 1011 /* enable nonblocking unless tty */ 1012 if (!isatty(new_fd[0])) 1013 set_nonblock(new_fd[0]); 1014 if (!isatty(new_fd[1])) 1015 set_nonblock(new_fd[1]); 1016 1017 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1018 1019 nc->ctl_chan = c->self; /* link session -> control channel */ 1020 c->remote_id = nc->self; /* link control -> session channel */ 1021 1022 debug2("%s: channel_new: %d linked to control channel %d", 1023 __func__, nc->self, nc->ctl_chan); 1024 1025 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1026 1027 cctx = xcalloc(1, sizeof(*cctx)); 1028 cctx->rid = rid; 1029 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1030 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1031 1032 /* reply is deferred, sent by mux_session_confirm */ 1033 return 0; 1034} 1035 1036/* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1037static void 1038mux_stdio_confirm(int id, int success, void *arg) 1039{ 1040 struct mux_stdio_confirm_ctx *cctx = arg; 1041 Channel *c, *cc; 1042 Buffer reply; 1043 1044 if (cctx == NULL) 1045 fatal("%s: cctx == NULL", __func__); 1046 if ((c = channel_by_id(id)) == NULL) 1047 fatal("%s: no channel for id %d", __func__, id); 1048 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1049 fatal("%s: channel %d lacks control channel %d", __func__, 1050 id, c->ctl_chan); 1051 1052 if (!success) { 1053 debug3("%s: sending failure reply", __func__); 1054 /* prepare reply */ 1055 buffer_init(&reply); 1056 buffer_put_int(&reply, MUX_S_FAILURE); 1057 buffer_put_int(&reply, cctx->rid); 1058 buffer_put_cstring(&reply, "Session open refused by peer"); 1059 goto done; 1060 } 1061 1062 debug3("%s: sending success reply", __func__); 1063 /* prepare reply */ 1064 buffer_init(&reply); 1065 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1066 buffer_put_int(&reply, cctx->rid); 1067 buffer_put_int(&reply, c->self); 1068 1069 done: 1070 /* Send reply */ 1071 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1072 buffer_free(&reply); 1073 1074 if (cc->mux_pause <= 0) 1075 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1076 cc->mux_pause = 0; /* start processing messages again */ 1077 c->open_confirm_ctx = NULL; 1078 free(cctx); 1079} 1080 1081static int 1082process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1083{ 1084 debug("%s: channel %d: stop listening", __func__, c->self); 1085 1086 if (options.control_master == SSHCTL_MASTER_ASK || 1087 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1088 if (!ask_permission("Disable further multiplexing on shared " 1089 "connection to %s? ", host)) { 1090 debug2("%s: stop listen refused by user", __func__); 1091 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1092 buffer_put_int(r, rid); 1093 buffer_put_cstring(r, "Permission denied"); 1094 return 0; 1095 } 1096 } 1097 1098 if (mux_listener_channel != NULL) { 1099 channel_free(mux_listener_channel); 1100 client_stop_mux(); 1101 free(options.control_path); 1102 options.control_path = NULL; 1103 mux_listener_channel = NULL; 1104 muxserver_sock = -1; 1105 } 1106 1107 /* prepare reply */ 1108 buffer_put_int(r, MUX_S_OK); 1109 buffer_put_int(r, rid); 1110 1111 return 0; 1112} 1113 1114/* Channel callbacks fired on read/write from mux slave fd */ 1115static int 1116mux_master_read_cb(Channel *c) 1117{ 1118 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1119 Buffer in, out; 1120 const u_char *ptr; 1121 u_int type, rid, have, i; 1122 int ret = -1; 1123 1124 /* Setup ctx and */ 1125 if (c->mux_ctx == NULL) { 1126 state = xcalloc(1, sizeof(*state)); 1127 c->mux_ctx = state; 1128 channel_register_cleanup(c->self, 1129 mux_master_control_cleanup_cb, 0); 1130 1131 /* Send hello */ 1132 buffer_init(&out); 1133 buffer_put_int(&out, MUX_MSG_HELLO); 1134 buffer_put_int(&out, SSHMUX_VER); 1135 /* no extensions */ 1136 buffer_put_string(&c->output, buffer_ptr(&out), 1137 buffer_len(&out)); 1138 buffer_free(&out); 1139 debug3("%s: channel %d: hello sent", __func__, c->self); 1140 return 0; 1141 } 1142 1143 buffer_init(&in); 1144 buffer_init(&out); 1145 1146 /* Channel code ensures that we receive whole packets */ 1147 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1148 malf: 1149 error("%s: malformed message", __func__); 1150 goto out; 1151 } 1152 buffer_append(&in, ptr, have); 1153 1154 if (buffer_get_int_ret(&type, &in) != 0) 1155 goto malf; 1156 debug3("%s: channel %d packet type 0x%08x len %u", 1157 __func__, c->self, type, buffer_len(&in)); 1158 1159 if (type == MUX_MSG_HELLO) 1160 rid = 0; 1161 else { 1162 if (!state->hello_rcvd) { 1163 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1164 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1165 goto out; 1166 } 1167 if (buffer_get_int_ret(&rid, &in) != 0) 1168 goto malf; 1169 } 1170 1171 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1172 if (type == mux_master_handlers[i].type) { 1173 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1174 break; 1175 } 1176 } 1177 if (mux_master_handlers[i].handler == NULL) { 1178 error("%s: unsupported mux message 0x%08x", __func__, type); 1179 buffer_put_int(&out, MUX_S_FAILURE); 1180 buffer_put_int(&out, rid); 1181 buffer_put_cstring(&out, "unsupported request"); 1182 ret = 0; 1183 } 1184 /* Enqueue reply packet */ 1185 if (buffer_len(&out) != 0) { 1186 buffer_put_string(&c->output, buffer_ptr(&out), 1187 buffer_len(&out)); 1188 } 1189 out: 1190 buffer_free(&in); 1191 buffer_free(&out); 1192 return ret; 1193} 1194 1195void 1196mux_exit_message(Channel *c, int exitval) 1197{ 1198 Buffer m; 1199 Channel *mux_chan; 1200 1201 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1202 exitval); 1203 1204 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1205 fatal("%s: channel %d missing mux channel %d", 1206 __func__, c->self, c->ctl_chan); 1207 1208 /* Append exit message packet to control socket output queue */ 1209 buffer_init(&m); 1210 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1211 buffer_put_int(&m, c->self); 1212 buffer_put_int(&m, exitval); 1213 1214 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1215 buffer_free(&m); 1216} 1217 1218void 1219mux_tty_alloc_failed(Channel *c) 1220{ 1221 Buffer m; 1222 Channel *mux_chan; 1223 1224 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1225 1226 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1227 fatal("%s: channel %d missing mux channel %d", 1228 __func__, c->self, c->ctl_chan); 1229 1230 /* Append exit message packet to control socket output queue */ 1231 buffer_init(&m); 1232 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1233 buffer_put_int(&m, c->self); 1234 1235 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1236 buffer_free(&m); 1237} 1238 1239/* Prepare a mux master to listen on a Unix domain socket. */ 1240void 1241muxserver_listen(void) 1242{ 1243 mode_t old_umask; 1244 char *orig_control_path = options.control_path; 1245 char rbuf[16+1]; 1246 u_int i, r; 1247 int oerrno; 1248 1249 if (options.control_path == NULL || 1250 options.control_master == SSHCTL_MASTER_NO) 1251 return; 1252 1253 debug("setting up multiplex master socket"); 1254 1255 /* 1256 * Use a temporary path before listen so we can pseudo-atomically 1257 * establish the listening socket in its final location to avoid 1258 * other processes racing in between bind() and listen() and hitting 1259 * an unready socket. 1260 */ 1261 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1262 r = arc4random_uniform(26+26+10); 1263 rbuf[i] = (r < 26) ? 'a' + r : 1264 (r < 26*2) ? 'A' + r - 26 : 1265 '0' + r - 26 - 26; 1266 } 1267 rbuf[sizeof(rbuf) - 1] = '\0'; 1268 options.control_path = NULL; 1269 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1270 debug3("%s: temporary control path %s", __func__, options.control_path); 1271 1272 old_umask = umask(0177); 1273 muxserver_sock = unix_listener(options.control_path, 64, 0); 1274 oerrno = errno; 1275 umask(old_umask); 1276 if (muxserver_sock < 0) { 1277 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1278 error("ControlSocket %s already exists, " 1279 "disabling multiplexing", options.control_path); 1280 disable_mux_master: 1281 if (muxserver_sock != -1) { 1282 close(muxserver_sock); 1283 muxserver_sock = -1; 1284 } 1285 free(orig_control_path); 1286 free(options.control_path); 1287 options.control_path = NULL; 1288 options.control_master = SSHCTL_MASTER_NO; 1289 return; 1290 } else { 1291 /* unix_listener() logs the error */ 1292 cleanup_exit(255); 1293 } 1294 } 1295 1296 /* Now atomically "move" the mux socket into position */ 1297 if (link(options.control_path, orig_control_path) != 0) { 1298 if (errno != EEXIST) { 1299 fatal("%s: link mux listener %s => %s: %s", __func__, 1300 options.control_path, orig_control_path, 1301 strerror(errno)); 1302 } 1303 error("ControlSocket %s already exists, disabling multiplexing", 1304 orig_control_path); 1305 unlink(options.control_path); 1306 goto disable_mux_master; 1307 } 1308 unlink(options.control_path); 1309 free(options.control_path); 1310 options.control_path = orig_control_path; 1311 1312 set_nonblock(muxserver_sock); 1313 1314 mux_listener_channel = channel_new("mux listener", 1315 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1316 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1317 0, options.control_path, 1); 1318 mux_listener_channel->mux_rcb = mux_master_read_cb; 1319 debug3("%s: mux listener channel %d fd %d", __func__, 1320 mux_listener_channel->self, mux_listener_channel->sock); 1321} 1322 1323/* Callback on open confirmation in mux master for a mux client session. */ 1324static void 1325mux_session_confirm(int id, int success, void *arg) 1326{ 1327 struct mux_session_confirm_ctx *cctx = arg; 1328 const char *display; 1329 Channel *c, *cc; 1330 int i; 1331 Buffer reply; 1332 1333 if (cctx == NULL) 1334 fatal("%s: cctx == NULL", __func__); 1335 if ((c = channel_by_id(id)) == NULL) 1336 fatal("%s: no channel for id %d", __func__, id); 1337 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1338 fatal("%s: channel %d lacks control channel %d", __func__, 1339 id, c->ctl_chan); 1340 1341 if (!success) { 1342 debug3("%s: sending failure reply", __func__); 1343 /* prepare reply */ 1344 buffer_init(&reply); 1345 buffer_put_int(&reply, MUX_S_FAILURE); 1346 buffer_put_int(&reply, cctx->rid); 1347 buffer_put_cstring(&reply, "Session open refused by peer"); 1348 goto done; 1349 } 1350 1351 display = getenv("DISPLAY"); 1352 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1353 char *proto, *data; 1354 1355 /* Get reasonable local authentication information. */ 1356 if (client_x11_get_proto(display, options.xauth_location, 1357 options.forward_x11_trusted, options.forward_x11_timeout, 1358 &proto, &data) == 0) { 1359 /* Request forwarding with authentication spoofing. */ 1360 debug("Requesting X11 forwarding with authentication " 1361 "spoofing."); 1362 x11_request_forwarding_with_spoofing(id, display, proto, 1363 data, 1); 1364 /* XXX exit_on_forward_failure */ 1365 client_expect_confirm(id, "X11 forwarding", 1366 CONFIRM_WARN); 1367 } 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, "%i\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 if (pledge("stdio proc tty", NULL) == -1) 1894 fatal("%s pledge(): %s", __func__, strerror(errno)); 1895 platform_pledge_mux(); 1896 1897 signal(SIGHUP, control_client_sighandler); 1898 signal(SIGINT, control_client_sighandler); 1899 signal(SIGTERM, control_client_sighandler); 1900 signal(SIGWINCH, control_client_sigrelay); 1901 1902 rawmode = tty_flag; 1903 if (tty_flag) 1904 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1905 1906 /* 1907 * Stick around until the controlee closes the client_fd. 1908 * Before it does, it is expected to write an exit message. 1909 * This process must read the value and wait for the closure of 1910 * the client_fd; if this one closes early, the multiplex master will 1911 * terminate early too (possibly losing data). 1912 */ 1913 for (exitval = 255, exitval_seen = 0;;) { 1914 buffer_clear(&m); 1915 if (mux_client_read_packet(fd, &m) != 0) 1916 break; 1917 type = buffer_get_int(&m); 1918 switch (type) { 1919 case MUX_S_TTY_ALLOC_FAIL: 1920 if ((esid = buffer_get_int(&m)) != sid) 1921 fatal("%s: tty alloc fail on unknown session: " 1922 "my id %u theirs %u", 1923 __func__, sid, esid); 1924 leave_raw_mode(options.request_tty == 1925 REQUEST_TTY_FORCE); 1926 rawmode = 0; 1927 continue; 1928 case MUX_S_EXIT_MESSAGE: 1929 if ((esid = buffer_get_int(&m)) != sid) 1930 fatal("%s: exit on unknown session: " 1931 "my id %u theirs %u", 1932 __func__, sid, esid); 1933 if (exitval_seen) 1934 fatal("%s: exitval sent twice", __func__); 1935 exitval = buffer_get_int(&m); 1936 exitval_seen = 1; 1937 continue; 1938 default: 1939 e = buffer_get_string(&m, NULL); 1940 fatal("%s: master returned error: %s", __func__, e); 1941 } 1942 } 1943 1944 close(fd); 1945 if (rawmode) 1946 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1947 1948 if (muxclient_terminate) { 1949 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1950 exitval = 255; 1951 } else if (!exitval_seen) { 1952 debug2("Control master terminated unexpectedly"); 1953 exitval = 255; 1954 } else 1955 debug2("Received exit status from master %d", exitval); 1956 1957 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1958 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1959 1960 exit(exitval); 1961} 1962 1963static int 1964mux_client_request_stdio_fwd(int fd) 1965{ 1966 Buffer m; 1967 char *e; 1968 u_int type, rid, sid; 1969 int devnull; 1970 1971 debug3("%s: entering", __func__); 1972 1973 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1974 error("%s: master alive request failed", __func__); 1975 return -1; 1976 } 1977 1978 signal(SIGPIPE, SIG_IGN); 1979 1980 if (stdin_null_flag) { 1981 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1982 fatal("open(/dev/null): %s", strerror(errno)); 1983 if (dup2(devnull, STDIN_FILENO) == -1) 1984 fatal("dup2: %s", strerror(errno)); 1985 if (devnull > STDERR_FILENO) 1986 close(devnull); 1987 } 1988 1989 buffer_init(&m); 1990 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1991 buffer_put_int(&m, muxclient_request_id); 1992 buffer_put_cstring(&m, ""); /* reserved */ 1993 buffer_put_cstring(&m, options.stdio_forward_host); 1994 buffer_put_int(&m, options.stdio_forward_port); 1995 1996 if (mux_client_write_packet(fd, &m) != 0) 1997 fatal("%s: write packet: %s", __func__, strerror(errno)); 1998 1999 /* Send the stdio file descriptors */ 2000 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2001 mm_send_fd(fd, STDOUT_FILENO) == -1) 2002 fatal("%s: send fds failed", __func__); 2003 2004 if (pledge("stdio proc tty", NULL) == -1) 2005 fatal("%s pledge(): %s", __func__, strerror(errno)); 2006 platform_pledge_mux(); 2007 2008 debug3("%s: stdio forward request sent", __func__); 2009 2010 /* Read their reply */ 2011 buffer_clear(&m); 2012 2013 if (mux_client_read_packet(fd, &m) != 0) { 2014 error("%s: read from master failed: %s", 2015 __func__, strerror(errno)); 2016 buffer_free(&m); 2017 return -1; 2018 } 2019 2020 type = buffer_get_int(&m); 2021 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2022 fatal("%s: out of sequence reply: my id %u theirs %u", 2023 __func__, muxclient_request_id, rid); 2024 switch (type) { 2025 case MUX_S_SESSION_OPENED: 2026 sid = buffer_get_int(&m); 2027 debug("%s: master session id: %u", __func__, sid); 2028 break; 2029 case MUX_S_PERMISSION_DENIED: 2030 e = buffer_get_string(&m, NULL); 2031 buffer_free(&m); 2032 fatal("Master refused stdio forwarding request: %s", e); 2033 case MUX_S_FAILURE: 2034 e = buffer_get_string(&m, NULL); 2035 buffer_free(&m); 2036 fatal("Stdio forwarding request failed: %s", e); 2037 default: 2038 buffer_free(&m); 2039 error("%s: unexpected response from master 0x%08x", 2040 __func__, type); 2041 return -1; 2042 } 2043 muxclient_request_id++; 2044 2045 signal(SIGHUP, control_client_sighandler); 2046 signal(SIGINT, control_client_sighandler); 2047 signal(SIGTERM, control_client_sighandler); 2048 signal(SIGWINCH, control_client_sigrelay); 2049 2050 /* 2051 * Stick around until the controlee closes the client_fd. 2052 */ 2053 buffer_clear(&m); 2054 if (mux_client_read_packet(fd, &m) != 0) { 2055 if (errno == EPIPE || 2056 (errno == EINTR && muxclient_terminate != 0)) 2057 return 0; 2058 fatal("%s: mux_client_read_packet: %s", 2059 __func__, strerror(errno)); 2060 } 2061 fatal("%s: master returned unexpected message %u", __func__, type); 2062} 2063 2064static void 2065mux_client_request_stop_listening(int fd) 2066{ 2067 Buffer m; 2068 char *e; 2069 u_int type, rid; 2070 2071 debug3("%s: entering", __func__); 2072 2073 buffer_init(&m); 2074 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2075 buffer_put_int(&m, muxclient_request_id); 2076 2077 if (mux_client_write_packet(fd, &m) != 0) 2078 fatal("%s: write packet: %s", __func__, strerror(errno)); 2079 2080 buffer_clear(&m); 2081 2082 /* Read their reply */ 2083 if (mux_client_read_packet(fd, &m) != 0) 2084 fatal("%s: read from master failed: %s", 2085 __func__, strerror(errno)); 2086 2087 type = buffer_get_int(&m); 2088 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2089 fatal("%s: out of sequence reply: my id %u theirs %u", 2090 __func__, muxclient_request_id, rid); 2091 switch (type) { 2092 case MUX_S_OK: 2093 break; 2094 case MUX_S_PERMISSION_DENIED: 2095 e = buffer_get_string(&m, NULL); 2096 fatal("Master refused stop listening request: %s", e); 2097 case MUX_S_FAILURE: 2098 e = buffer_get_string(&m, NULL); 2099 fatal("%s: stop listening request failed: %s", __func__, e); 2100 default: 2101 fatal("%s: unexpected response from master 0x%08x", 2102 __func__, type); 2103 } 2104 buffer_free(&m); 2105 muxclient_request_id++; 2106} 2107 2108/* Multiplex client main loop. */ 2109void 2110muxclient(const char *path) 2111{ 2112 struct sockaddr_un addr; 2113 socklen_t sun_len; 2114 int sock; 2115 u_int pid; 2116 2117 if (muxclient_command == 0) { 2118 if (options.stdio_forward_host != NULL) 2119 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2120 else 2121 muxclient_command = SSHMUX_COMMAND_OPEN; 2122 } 2123 2124 switch (options.control_master) { 2125 case SSHCTL_MASTER_AUTO: 2126 case SSHCTL_MASTER_AUTO_ASK: 2127 debug("auto-mux: Trying existing master"); 2128 /* FALLTHROUGH */ 2129 case SSHCTL_MASTER_NO: 2130 break; 2131 default: 2132 return; 2133 } 2134 2135 memset(&addr, '\0', sizeof(addr)); 2136 addr.sun_family = AF_UNIX; 2137 sun_len = offsetof(struct sockaddr_un, sun_path) + 2138 strlen(path) + 1; 2139 2140 if (strlcpy(addr.sun_path, path, 2141 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2142 fatal("ControlPath too long"); 2143 2144 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2145 fatal("%s socket(): %s", __func__, strerror(errno)); 2146 2147 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2148 switch (muxclient_command) { 2149 case SSHMUX_COMMAND_OPEN: 2150 case SSHMUX_COMMAND_STDIO_FWD: 2151 break; 2152 default: 2153 fatal("Control socket connect(%.100s): %s", path, 2154 strerror(errno)); 2155 } 2156 if (errno == ECONNREFUSED && 2157 options.control_master != SSHCTL_MASTER_NO) { 2158 debug("Stale control socket %.100s, unlinking", path); 2159 unlink(path); 2160 } else if (errno == ENOENT) { 2161 debug("Control socket \"%.100s\" does not exist", path); 2162 } else { 2163 error("Control socket connect(%.100s): %s", path, 2164 strerror(errno)); 2165 } 2166 close(sock); 2167 return; 2168 } 2169 set_nonblock(sock); 2170 2171 if (mux_client_hello_exchange(sock) != 0) { 2172 error("%s: master hello exchange failed", __func__); 2173 close(sock); 2174 return; 2175 } 2176 2177 switch (muxclient_command) { 2178 case SSHMUX_COMMAND_ALIVE_CHECK: 2179 if ((pid = mux_client_request_alive(sock)) == 0) 2180 fatal("%s: master alive check failed", __func__); 2181 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2182 exit(0); 2183 case SSHMUX_COMMAND_TERMINATE: 2184 mux_client_request_terminate(sock); 2185 fprintf(stderr, "Exit request sent.\r\n"); 2186 exit(0); 2187 case SSHMUX_COMMAND_FORWARD: 2188 if (mux_client_forwards(sock, 0) != 0) 2189 fatal("%s: master forward request failed", __func__); 2190 exit(0); 2191 case SSHMUX_COMMAND_OPEN: 2192 if (mux_client_forwards(sock, 0) != 0) { 2193 error("%s: master forward request failed", __func__); 2194 return; 2195 } 2196 mux_client_request_session(sock); 2197 return; 2198 case SSHMUX_COMMAND_STDIO_FWD: 2199 mux_client_request_stdio_fwd(sock); 2200 exit(0); 2201 case SSHMUX_COMMAND_STOP: 2202 mux_client_request_stop_listening(sock); 2203 fprintf(stderr, "Stop listening request sent.\r\n"); 2204 exit(0); 2205 case SSHMUX_COMMAND_CANCEL_FWD: 2206 if (mux_client_forwards(sock, 1) != 0) 2207 error("%s: master cancel forward request failed", 2208 __func__); 2209 exit(0); 2210 default: 2211 fatal("unrecognised muxclient_command %d", muxclient_command); 2212 } 2213} 2214