mux.c revision 323121
1/* $OpenBSD: mux.c,v 1.58 2016/01/13 23:04:47 djm Exp $ */ 2/* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18/* ssh session multiplexing support */ 19 20/* 21 * TODO: 22 * - Better signalling from master to slave, especially passing of 23 * error messages 24 * - Better fall-back from mux slave error to new connection. 25 * - ExitOnForwardingFailure 26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 27 * - Support ~^Z in mux slaves. 28 * - Inspect or control sessions in master. 29 * - If we ever support the "signal" channel request, send signals on 30 * sessions in master. 31 */ 32 33#include "includes.h" 34__RCSID("$FreeBSD: stable/10/crypto/openssh/mux.c 323121 2017-09-01 21:48:36Z des $"); 35 36#include <sys/types.h> 37#include <sys/stat.h> 38#include <sys/socket.h> 39#include <sys/un.h> 40 41#include <errno.h> 42#include <fcntl.h> 43#include <signal.h> 44#include <stdarg.h> 45#include <stddef.h> 46#include <stdlib.h> 47#include <stdio.h> 48#include <string.h> 49#include <unistd.h> 50#ifdef HAVE_PATHS_H 51#include <paths.h> 52#endif 53 54#ifdef HAVE_POLL_H 55#include <poll.h> 56#else 57# ifdef HAVE_SYS_POLL_H 58# include <sys/poll.h> 59# endif 60#endif 61 62#ifdef HAVE_UTIL_H 63# include <util.h> 64#endif 65 66#include "openbsd-compat/sys-queue.h" 67#include "xmalloc.h" 68#include "log.h" 69#include "ssh.h" 70#include "ssh2.h" 71#include "pathnames.h" 72#include "misc.h" 73#include "match.h" 74#include "buffer.h" 75#include "channels.h" 76#include "msg.h" 77#include "packet.h" 78#include "monitor_fdpass.h" 79#include "sshpty.h" 80#include "key.h" 81#include "readconf.h" 82#include "clientloop.h" 83 84/* from ssh.c */ 85extern int tty_flag; 86extern Options options; 87extern int stdin_null_flag; 88extern char *host; 89extern int subsystem_flag; 90extern Buffer command; 91extern volatile sig_atomic_t quit_pending; 92extern char *stdio_forward_host; 93extern int stdio_forward_port; 94 95/* Context for session open confirmation callback */ 96struct mux_session_confirm_ctx { 97 u_int want_tty; 98 u_int want_subsys; 99 u_int want_x_fwd; 100 u_int want_agent_fwd; 101 Buffer cmd; 102 char *term; 103 struct termios tio; 104 char **env; 105 u_int rid; 106}; 107 108/* Context for stdio fwd open confirmation callback */ 109struct mux_stdio_confirm_ctx { 110 u_int rid; 111}; 112 113/* Context for global channel callback */ 114struct mux_channel_confirm_ctx { 115 u_int cid; /* channel id */ 116 u_int rid; /* request id */ 117 int fid; /* forward id */ 118}; 119 120/* fd to control socket */ 121int muxserver_sock = -1; 122 123/* client request id */ 124u_int muxclient_request_id = 0; 125 126/* Multiplexing control command */ 127u_int muxclient_command = 0; 128 129/* Set when signalled. */ 130static volatile sig_atomic_t muxclient_terminate = 0; 131 132/* PID of multiplex server */ 133static u_int muxserver_pid = 0; 134 135static Channel *mux_listener_channel = NULL; 136 137struct mux_master_state { 138 int hello_rcvd; 139}; 140 141/* mux protocol messages */ 142#define MUX_MSG_HELLO 0x00000001 143#define MUX_C_NEW_SESSION 0x10000002 144#define MUX_C_ALIVE_CHECK 0x10000004 145#define MUX_C_TERMINATE 0x10000005 146#define MUX_C_OPEN_FWD 0x10000006 147#define MUX_C_CLOSE_FWD 0x10000007 148#define MUX_C_NEW_STDIO_FWD 0x10000008 149#define MUX_C_STOP_LISTENING 0x10000009 150#define MUX_S_OK 0x80000001 151#define MUX_S_PERMISSION_DENIED 0x80000002 152#define MUX_S_FAILURE 0x80000003 153#define MUX_S_EXIT_MESSAGE 0x80000004 154#define MUX_S_ALIVE 0x80000005 155#define MUX_S_SESSION_OPENED 0x80000006 156#define MUX_S_REMOTE_PORT 0x80000007 157#define MUX_S_TTY_ALLOC_FAIL 0x80000008 158 159/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 160#define MUX_FWD_LOCAL 1 161#define MUX_FWD_REMOTE 2 162#define MUX_FWD_DYNAMIC 3 163 164static void mux_session_confirm(int, int, void *); 165static void mux_stdio_confirm(int, int, void *); 166 167static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 168static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 169static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 170static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 171static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 172static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 173static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 174static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 175 176static const struct { 177 u_int type; 178 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 179} mux_master_handlers[] = { 180 { MUX_MSG_HELLO, process_mux_master_hello }, 181 { MUX_C_NEW_SESSION, process_mux_new_session }, 182 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 183 { MUX_C_TERMINATE, process_mux_terminate }, 184 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 185 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 186 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 187 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 188 { 0, NULL } 189}; 190 191/* Cleanup callback fired on closure of mux slave _session_ channel */ 192/* ARGSUSED */ 193static void 194mux_master_session_cleanup_cb(int cid, void *unused) 195{ 196 Channel *cc, *c = channel_by_id(cid); 197 198 debug3("%s: entering for channel %d", __func__, cid); 199 if (c == NULL) 200 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 201 if (c->ctl_chan != -1) { 202 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 203 fatal("%s: channel %d missing control channel %d", 204 __func__, c->self, c->ctl_chan); 205 c->ctl_chan = -1; 206 cc->remote_id = -1; 207 chan_rcvd_oclose(cc); 208 } 209 channel_cancel_cleanup(c->self); 210} 211 212/* Cleanup callback fired on closure of mux slave _control_ channel */ 213/* ARGSUSED */ 214static void 215mux_master_control_cleanup_cb(int cid, void *unused) 216{ 217 Channel *sc, *c = channel_by_id(cid); 218 219 debug3("%s: entering for channel %d", __func__, cid); 220 if (c == NULL) 221 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 222 if (c->remote_id != -1) { 223 if ((sc = channel_by_id(c->remote_id)) == NULL) 224 fatal("%s: channel %d missing session channel %d", 225 __func__, c->self, c->remote_id); 226 c->remote_id = -1; 227 sc->ctl_chan = -1; 228 if (sc->type != SSH_CHANNEL_OPEN && 229 sc->type != SSH_CHANNEL_OPENING) { 230 debug2("%s: channel %d: not open", __func__, sc->self); 231 chan_mark_dead(sc); 232 } else { 233 if (sc->istate == CHAN_INPUT_OPEN) 234 chan_read_failed(sc); 235 if (sc->ostate == CHAN_OUTPUT_OPEN) 236 chan_write_failed(sc); 237 } 238 } 239 channel_cancel_cleanup(c->self); 240} 241 242/* Check mux client environment variables before passing them to mux master. */ 243static int 244env_permitted(char *env) 245{ 246 int i, ret; 247 char name[1024], *cp; 248 249 if ((cp = strchr(env, '=')) == NULL || cp == env) 250 return 0; 251 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 252 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 253 error("env_permitted: name '%.100s...' too long", env); 254 return 0; 255 } 256 257 for (i = 0; i < options.num_send_env; i++) 258 if (match_pattern(name, options.send_env[i])) 259 return 1; 260 261 return 0; 262} 263 264/* Mux master protocol message handlers */ 265 266static int 267process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 268{ 269 u_int ver; 270 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 271 272 if (state == NULL) 273 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 274 if (state->hello_rcvd) { 275 error("%s: HELLO received twice", __func__); 276 return -1; 277 } 278 if (buffer_get_int_ret(&ver, m) != 0) { 279 malf: 280 error("%s: malformed message", __func__); 281 return -1; 282 } 283 if (ver != SSHMUX_VER) { 284 error("Unsupported multiplexing protocol version %d " 285 "(expected %d)", ver, SSHMUX_VER); 286 return -1; 287 } 288 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 289 290 /* No extensions are presently defined */ 291 while (buffer_len(m) > 0) { 292 char *name = buffer_get_string_ret(m, NULL); 293 char *value = buffer_get_string_ret(m, NULL); 294 295 if (name == NULL || value == NULL) { 296 free(name); 297 free(value); 298 goto malf; 299 } 300 debug2("Unrecognised slave extension \"%s\"", name); 301 free(name); 302 free(value); 303 } 304 state->hello_rcvd = 1; 305 return 0; 306} 307 308static int 309process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 310{ 311 Channel *nc; 312 struct mux_session_confirm_ctx *cctx; 313 char *reserved, *cmd, *cp; 314 u_int i, j, len, env_len, escape_char, window, packetmax; 315 int new_fd[3]; 316 317 /* Reply for SSHMUX_COMMAND_OPEN */ 318 cctx = xcalloc(1, sizeof(*cctx)); 319 cctx->term = NULL; 320 cctx->rid = rid; 321 cmd = reserved = NULL; 322 cctx->env = NULL; 323 env_len = 0; 324 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 325 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 326 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 327 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 328 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 329 buffer_get_int_ret(&escape_char, m) != 0 || 330 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 331 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 332 malf: 333 free(cmd); 334 free(reserved); 335 for (j = 0; j < env_len; j++) 336 free(cctx->env[j]); 337 free(cctx->env); 338 free(cctx->term); 339 free(cctx); 340 error("%s: malformed message", __func__); 341 return -1; 342 } 343 free(reserved); 344 reserved = NULL; 345 346 while (buffer_len(m) > 0) { 347#define MUX_MAX_ENV_VARS 4096 348 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 349 goto malf; 350 if (!env_permitted(cp)) { 351 free(cp); 352 continue; 353 } 354 cctx->env = xreallocarray(cctx->env, env_len + 2, 355 sizeof(*cctx->env)); 356 cctx->env[env_len++] = cp; 357 cctx->env[env_len] = NULL; 358 if (env_len > MUX_MAX_ENV_VARS) { 359 error(">%d environment variables received, ignoring " 360 "additional", MUX_MAX_ENV_VARS); 361 break; 362 } 363 } 364 365 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 366 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 367 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 368 cctx->want_subsys, cctx->term, cmd, env_len); 369 370 buffer_init(&cctx->cmd); 371 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 372 free(cmd); 373 cmd = NULL; 374 375 /* Gather fds from client */ 376 for(i = 0; i < 3; i++) { 377 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 378 error("%s: failed to receive fd %d from slave", 379 __func__, i); 380 for (j = 0; j < i; j++) 381 close(new_fd[j]); 382 for (j = 0; j < env_len; j++) 383 free(cctx->env[j]); 384 free(cctx->env); 385 free(cctx->term); 386 buffer_free(&cctx->cmd); 387 free(cctx); 388 389 /* prepare reply */ 390 buffer_put_int(r, MUX_S_FAILURE); 391 buffer_put_int(r, rid); 392 buffer_put_cstring(r, 393 "did not receive file descriptors"); 394 return -1; 395 } 396 } 397 398 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 399 new_fd[0], new_fd[1], new_fd[2]); 400 401 /* XXX support multiple child sessions in future */ 402 if (c->remote_id != -1) { 403 debug2("%s: session already open", __func__); 404 /* prepare reply */ 405 buffer_put_int(r, MUX_S_FAILURE); 406 buffer_put_int(r, rid); 407 buffer_put_cstring(r, "Multiple sessions not supported"); 408 cleanup: 409 close(new_fd[0]); 410 close(new_fd[1]); 411 close(new_fd[2]); 412 free(cctx->term); 413 if (env_len != 0) { 414 for (i = 0; i < env_len; i++) 415 free(cctx->env[i]); 416 free(cctx->env); 417 } 418 buffer_free(&cctx->cmd); 419 free(cctx); 420 return 0; 421 } 422 423 if (options.control_master == SSHCTL_MASTER_ASK || 424 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 425 if (!ask_permission("Allow shared connection to %s? ", host)) { 426 debug2("%s: session refused by user", __func__); 427 /* prepare reply */ 428 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 429 buffer_put_int(r, rid); 430 buffer_put_cstring(r, "Permission denied"); 431 goto cleanup; 432 } 433 } 434 435 /* Try to pick up ttymodes from client before it goes raw */ 436 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 437 error("%s: tcgetattr: %s", __func__, strerror(errno)); 438 439 /* enable nonblocking unless tty */ 440 if (!isatty(new_fd[0])) 441 set_nonblock(new_fd[0]); 442 if (!isatty(new_fd[1])) 443 set_nonblock(new_fd[1]); 444 if (!isatty(new_fd[2])) 445 set_nonblock(new_fd[2]); 446 447 window = CHAN_SES_WINDOW_DEFAULT; 448 packetmax = CHAN_SES_PACKET_DEFAULT; 449 if (cctx->want_tty) { 450 window >>= 1; 451 packetmax >>= 1; 452 } 453 454 nc = channel_new("session", SSH_CHANNEL_OPENING, 455 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 456 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 457 458 nc->ctl_chan = c->self; /* link session -> control channel */ 459 c->remote_id = nc->self; /* link control -> session channel */ 460 461 if (cctx->want_tty && escape_char != 0xffffffff) { 462 channel_register_filter(nc->self, 463 client_simple_escape_filter, NULL, 464 client_filter_cleanup, 465 client_new_escape_filter_ctx((int)escape_char)); 466 } 467 468 debug2("%s: channel_new: %d linked to control channel %d", 469 __func__, nc->self, nc->ctl_chan); 470 471 channel_send_open(nc->self); 472 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 473 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 474 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 475 476 /* reply is deferred, sent by mux_session_confirm */ 477 return 0; 478} 479 480static int 481process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 482{ 483 debug2("%s: channel %d: alive check", __func__, c->self); 484 485 /* prepare reply */ 486 buffer_put_int(r, MUX_S_ALIVE); 487 buffer_put_int(r, rid); 488 buffer_put_int(r, (u_int)getpid()); 489 490 return 0; 491} 492 493static int 494process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 495{ 496 debug2("%s: channel %d: terminate request", __func__, c->self); 497 498 if (options.control_master == SSHCTL_MASTER_ASK || 499 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 500 if (!ask_permission("Terminate shared connection to %s? ", 501 host)) { 502 debug2("%s: termination refused by user", __func__); 503 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 504 buffer_put_int(r, rid); 505 buffer_put_cstring(r, "Permission denied"); 506 return 0; 507 } 508 } 509 510 quit_pending = 1; 511 buffer_put_int(r, MUX_S_OK); 512 buffer_put_int(r, rid); 513 /* XXX exit happens too soon - message never makes it to client */ 514 return 0; 515} 516 517static char * 518format_forward(u_int ftype, struct Forward *fwd) 519{ 520 char *ret; 521 522 switch (ftype) { 523 case MUX_FWD_LOCAL: 524 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 525 (fwd->listen_path != NULL) ? fwd->listen_path : 526 (fwd->listen_host == NULL) ? 527 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 528 fwd->listen_host, fwd->listen_port, 529 (fwd->connect_path != NULL) ? fwd->connect_path : 530 fwd->connect_host, fwd->connect_port); 531 break; 532 case MUX_FWD_DYNAMIC: 533 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 534 (fwd->listen_host == NULL) ? 535 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 536 fwd->listen_host, fwd->listen_port); 537 break; 538 case MUX_FWD_REMOTE: 539 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 540 (fwd->listen_path != NULL) ? fwd->listen_path : 541 (fwd->listen_host == NULL) ? 542 "LOCALHOST" : fwd->listen_host, 543 fwd->listen_port, 544 (fwd->connect_path != NULL) ? fwd->connect_path : 545 fwd->connect_host, fwd->connect_port); 546 break; 547 default: 548 fatal("%s: unknown forward type %u", __func__, ftype); 549 } 550 return ret; 551} 552 553static int 554compare_host(const char *a, const char *b) 555{ 556 if (a == NULL && b == NULL) 557 return 1; 558 if (a == NULL || b == NULL) 559 return 0; 560 return strcmp(a, b) == 0; 561} 562 563static int 564compare_forward(struct Forward *a, struct Forward *b) 565{ 566 if (!compare_host(a->listen_host, b->listen_host)) 567 return 0; 568 if (!compare_host(a->listen_path, b->listen_path)) 569 return 0; 570 if (a->listen_port != b->listen_port) 571 return 0; 572 if (!compare_host(a->connect_host, b->connect_host)) 573 return 0; 574 if (!compare_host(a->connect_path, b->connect_path)) 575 return 0; 576 if (a->connect_port != b->connect_port) 577 return 0; 578 579 return 1; 580} 581 582static void 583mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 584{ 585 struct mux_channel_confirm_ctx *fctx = ctxt; 586 char *failmsg = NULL; 587 struct Forward *rfwd; 588 Channel *c; 589 Buffer out; 590 591 if ((c = channel_by_id(fctx->cid)) == NULL) { 592 /* no channel for reply */ 593 error("%s: unknown channel", __func__); 594 return; 595 } 596 buffer_init(&out); 597 if (fctx->fid >= options.num_remote_forwards || 598 (options.remote_forwards[fctx->fid].connect_path == NULL && 599 options.remote_forwards[fctx->fid].connect_host == NULL)) { 600 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 601 goto fail; 602 } 603 rfwd = &options.remote_forwards[fctx->fid]; 604 debug("%s: %s for: listen %d, connect %s:%d", __func__, 605 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 606 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 607 rfwd->connect_host, rfwd->connect_port); 608 if (type == SSH2_MSG_REQUEST_SUCCESS) { 609 if (rfwd->listen_port == 0) { 610 rfwd->allocated_port = packet_get_int(); 611 debug("Allocated port %u for mux remote forward" 612 " to %s:%d", rfwd->allocated_port, 613 rfwd->connect_host, rfwd->connect_port); 614 buffer_put_int(&out, MUX_S_REMOTE_PORT); 615 buffer_put_int(&out, fctx->rid); 616 buffer_put_int(&out, rfwd->allocated_port); 617 channel_update_permitted_opens(rfwd->handle, 618 rfwd->allocated_port); 619 } else { 620 buffer_put_int(&out, MUX_S_OK); 621 buffer_put_int(&out, fctx->rid); 622 } 623 goto out; 624 } else { 625 if (rfwd->listen_port == 0) 626 channel_update_permitted_opens(rfwd->handle, -1); 627 if (rfwd->listen_path != NULL) 628 xasprintf(&failmsg, "remote port forwarding failed for " 629 "listen path %s", rfwd->listen_path); 630 else 631 xasprintf(&failmsg, "remote port forwarding failed for " 632 "listen port %d", rfwd->listen_port); 633 634 debug2("%s: clearing registered forwarding for listen %d, " 635 "connect %s:%d", __func__, rfwd->listen_port, 636 rfwd->connect_path ? rfwd->connect_path : 637 rfwd->connect_host, rfwd->connect_port); 638 639 free(rfwd->listen_host); 640 free(rfwd->listen_path); 641 free(rfwd->connect_host); 642 free(rfwd->connect_path); 643 memset(rfwd, 0, sizeof(*rfwd)); 644 } 645 fail: 646 error("%s: %s", __func__, failmsg); 647 buffer_put_int(&out, MUX_S_FAILURE); 648 buffer_put_int(&out, fctx->rid); 649 buffer_put_cstring(&out, failmsg); 650 free(failmsg); 651 out: 652 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 653 buffer_free(&out); 654 if (c->mux_pause <= 0) 655 fatal("%s: mux_pause %d", __func__, c->mux_pause); 656 c->mux_pause = 0; /* start processing messages again */ 657} 658 659static int 660process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 661{ 662 struct Forward fwd; 663 char *fwd_desc = NULL; 664 char *listen_addr, *connect_addr; 665 u_int ftype; 666 u_int lport, cport; 667 int i, ret = 0, freefwd = 1; 668 669 memset(&fwd, 0, sizeof(fwd)); 670 671 /* XXX - lport/cport check redundant */ 672 if (buffer_get_int_ret(&ftype, m) != 0 || 673 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 674 buffer_get_int_ret(&lport, m) != 0 || 675 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 676 buffer_get_int_ret(&cport, m) != 0 || 677 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 678 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 679 error("%s: malformed message", __func__); 680 ret = -1; 681 goto out; 682 } 683 if (*listen_addr == '\0') { 684 free(listen_addr); 685 listen_addr = NULL; 686 } 687 if (*connect_addr == '\0') { 688 free(connect_addr); 689 connect_addr = NULL; 690 } 691 692 memset(&fwd, 0, sizeof(fwd)); 693 fwd.listen_port = lport; 694 if (fwd.listen_port == PORT_STREAMLOCAL) 695 fwd.listen_path = listen_addr; 696 else 697 fwd.listen_host = listen_addr; 698 fwd.connect_port = cport; 699 if (fwd.connect_port == PORT_STREAMLOCAL) 700 fwd.connect_path = connect_addr; 701 else 702 fwd.connect_host = connect_addr; 703 704 debug2("%s: channel %d: request %s", __func__, c->self, 705 (fwd_desc = format_forward(ftype, &fwd))); 706 707 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 708 ftype != MUX_FWD_DYNAMIC) { 709 logit("%s: invalid forwarding type %u", __func__, ftype); 710 invalid: 711 free(listen_addr); 712 free(connect_addr); 713 buffer_put_int(r, MUX_S_FAILURE); 714 buffer_put_int(r, rid); 715 buffer_put_cstring(r, "Invalid forwarding request"); 716 return 0; 717 } 718 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 719 logit("%s: streamlocal and dynamic forwards " 720 "are mutually exclusive", __func__); 721 goto invalid; 722 } 723 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 724 logit("%s: invalid listen port %u", __func__, 725 fwd.listen_port); 726 goto invalid; 727 } 728 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 729 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 730 logit("%s: invalid connect port %u", __func__, 731 fwd.connect_port); 732 goto invalid; 733 } 734 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 735 logit("%s: missing connect host", __func__); 736 goto invalid; 737 } 738 739 /* Skip forwards that have already been requested */ 740 switch (ftype) { 741 case MUX_FWD_LOCAL: 742 case MUX_FWD_DYNAMIC: 743 for (i = 0; i < options.num_local_forwards; i++) { 744 if (compare_forward(&fwd, 745 options.local_forwards + i)) { 746 exists: 747 debug2("%s: found existing forwarding", 748 __func__); 749 buffer_put_int(r, MUX_S_OK); 750 buffer_put_int(r, rid); 751 goto out; 752 } 753 } 754 break; 755 case MUX_FWD_REMOTE: 756 for (i = 0; i < options.num_remote_forwards; i++) { 757 if (compare_forward(&fwd, 758 options.remote_forwards + i)) { 759 if (fwd.listen_port != 0) 760 goto exists; 761 debug2("%s: found allocated port", 762 __func__); 763 buffer_put_int(r, MUX_S_REMOTE_PORT); 764 buffer_put_int(r, rid); 765 buffer_put_int(r, 766 options.remote_forwards[i].allocated_port); 767 goto out; 768 } 769 } 770 break; 771 } 772 773 if (options.control_master == SSHCTL_MASTER_ASK || 774 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 775 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 776 debug2("%s: forwarding refused by user", __func__); 777 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 778 buffer_put_int(r, rid); 779 buffer_put_cstring(r, "Permission denied"); 780 goto out; 781 } 782 } 783 784 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 785 if (!channel_setup_local_fwd_listener(&fwd, 786 &options.fwd_opts)) { 787 fail: 788 logit("slave-requested %s failed", fwd_desc); 789 buffer_put_int(r, MUX_S_FAILURE); 790 buffer_put_int(r, rid); 791 buffer_put_cstring(r, "Port forwarding failed"); 792 goto out; 793 } 794 add_local_forward(&options, &fwd); 795 freefwd = 0; 796 } else { 797 struct mux_channel_confirm_ctx *fctx; 798 799 fwd.handle = channel_request_remote_forwarding(&fwd); 800 if (fwd.handle < 0) 801 goto fail; 802 add_remote_forward(&options, &fwd); 803 fctx = xcalloc(1, sizeof(*fctx)); 804 fctx->cid = c->self; 805 fctx->rid = rid; 806 fctx->fid = options.num_remote_forwards - 1; 807 client_register_global_confirm(mux_confirm_remote_forward, 808 fctx); 809 freefwd = 0; 810 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 811 /* delayed reply in mux_confirm_remote_forward */ 812 goto out; 813 } 814 buffer_put_int(r, MUX_S_OK); 815 buffer_put_int(r, rid); 816 out: 817 free(fwd_desc); 818 if (freefwd) { 819 free(fwd.listen_host); 820 free(fwd.listen_path); 821 free(fwd.connect_host); 822 free(fwd.connect_path); 823 } 824 return ret; 825} 826 827static int 828process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 829{ 830 struct Forward fwd, *found_fwd; 831 char *fwd_desc = NULL; 832 const char *error_reason = NULL; 833 char *listen_addr = NULL, *connect_addr = NULL; 834 u_int ftype; 835 int i, ret = 0; 836 u_int lport, cport; 837 838 memset(&fwd, 0, sizeof(fwd)); 839 840 if (buffer_get_int_ret(&ftype, m) != 0 || 841 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 842 buffer_get_int_ret(&lport, m) != 0 || 843 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 844 buffer_get_int_ret(&cport, m) != 0 || 845 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 846 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 847 error("%s: malformed message", __func__); 848 ret = -1; 849 goto out; 850 } 851 852 if (*listen_addr == '\0') { 853 free(listen_addr); 854 listen_addr = NULL; 855 } 856 if (*connect_addr == '\0') { 857 free(connect_addr); 858 connect_addr = NULL; 859 } 860 861 memset(&fwd, 0, sizeof(fwd)); 862 fwd.listen_port = lport; 863 if (fwd.listen_port == PORT_STREAMLOCAL) 864 fwd.listen_path = listen_addr; 865 else 866 fwd.listen_host = listen_addr; 867 fwd.connect_port = cport; 868 if (fwd.connect_port == PORT_STREAMLOCAL) 869 fwd.connect_path = connect_addr; 870 else 871 fwd.connect_host = connect_addr; 872 873 debug2("%s: channel %d: request cancel %s", __func__, c->self, 874 (fwd_desc = format_forward(ftype, &fwd))); 875 876 /* make sure this has been requested */ 877 found_fwd = NULL; 878 switch (ftype) { 879 case MUX_FWD_LOCAL: 880 case MUX_FWD_DYNAMIC: 881 for (i = 0; i < options.num_local_forwards; i++) { 882 if (compare_forward(&fwd, 883 options.local_forwards + i)) { 884 found_fwd = options.local_forwards + i; 885 break; 886 } 887 } 888 break; 889 case MUX_FWD_REMOTE: 890 for (i = 0; i < options.num_remote_forwards; i++) { 891 if (compare_forward(&fwd, 892 options.remote_forwards + i)) { 893 found_fwd = options.remote_forwards + i; 894 break; 895 } 896 } 897 break; 898 } 899 900 if (found_fwd == NULL) 901 error_reason = "port not forwarded"; 902 else if (ftype == MUX_FWD_REMOTE) { 903 /* 904 * This shouldn't fail unless we confused the host/port 905 * between options.remote_forwards and permitted_opens. 906 * However, for dynamic allocated listen ports we need 907 * to use the actual listen port. 908 */ 909 if (channel_request_rforward_cancel(found_fwd) == -1) 910 error_reason = "port not in permitted opens"; 911 } else { /* local and dynamic forwards */ 912 /* Ditto */ 913 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 914 &options.fwd_opts) == -1) 915 error_reason = "port not found"; 916 } 917 918 if (error_reason == NULL) { 919 buffer_put_int(r, MUX_S_OK); 920 buffer_put_int(r, rid); 921 922 free(found_fwd->listen_host); 923 free(found_fwd->listen_path); 924 free(found_fwd->connect_host); 925 free(found_fwd->connect_path); 926 found_fwd->listen_host = found_fwd->connect_host = NULL; 927 found_fwd->listen_path = found_fwd->connect_path = NULL; 928 found_fwd->listen_port = found_fwd->connect_port = 0; 929 } else { 930 buffer_put_int(r, MUX_S_FAILURE); 931 buffer_put_int(r, rid); 932 buffer_put_cstring(r, error_reason); 933 } 934 out: 935 free(fwd_desc); 936 free(listen_addr); 937 free(connect_addr); 938 939 return ret; 940} 941 942static int 943process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 944{ 945 Channel *nc; 946 char *reserved, *chost; 947 u_int cport, i, j; 948 int new_fd[2]; 949 struct mux_stdio_confirm_ctx *cctx; 950 951 chost = reserved = NULL; 952 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 953 (chost = buffer_get_string_ret(m, NULL)) == NULL || 954 buffer_get_int_ret(&cport, m) != 0) { 955 free(reserved); 956 free(chost); 957 error("%s: malformed message", __func__); 958 return -1; 959 } 960 free(reserved); 961 962 debug2("%s: channel %d: request stdio fwd to %s:%u", 963 __func__, c->self, chost, cport); 964 965 /* Gather fds from client */ 966 for(i = 0; i < 2; i++) { 967 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 968 error("%s: failed to receive fd %d from slave", 969 __func__, i); 970 for (j = 0; j < i; j++) 971 close(new_fd[j]); 972 free(chost); 973 974 /* prepare reply */ 975 buffer_put_int(r, MUX_S_FAILURE); 976 buffer_put_int(r, rid); 977 buffer_put_cstring(r, 978 "did not receive file descriptors"); 979 return -1; 980 } 981 } 982 983 debug3("%s: got fds stdin %d, stdout %d", __func__, 984 new_fd[0], new_fd[1]); 985 986 /* XXX support multiple child sessions in future */ 987 if (c->remote_id != -1) { 988 debug2("%s: session already open", __func__); 989 /* prepare reply */ 990 buffer_put_int(r, MUX_S_FAILURE); 991 buffer_put_int(r, rid); 992 buffer_put_cstring(r, "Multiple sessions not supported"); 993 cleanup: 994 close(new_fd[0]); 995 close(new_fd[1]); 996 free(chost); 997 return 0; 998 } 999 1000 if (options.control_master == SSHCTL_MASTER_ASK || 1001 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1002 if (!ask_permission("Allow forward to %s:%u? ", 1003 chost, cport)) { 1004 debug2("%s: stdio fwd refused by user", __func__); 1005 /* prepare reply */ 1006 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1007 buffer_put_int(r, rid); 1008 buffer_put_cstring(r, "Permission denied"); 1009 goto cleanup; 1010 } 1011 } 1012 1013 /* enable nonblocking unless tty */ 1014 if (!isatty(new_fd[0])) 1015 set_nonblock(new_fd[0]); 1016 if (!isatty(new_fd[1])) 1017 set_nonblock(new_fd[1]); 1018 1019 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1020 1021 nc->ctl_chan = c->self; /* link session -> control channel */ 1022 c->remote_id = nc->self; /* link control -> session channel */ 1023 1024 debug2("%s: channel_new: %d linked to control channel %d", 1025 __func__, nc->self, nc->ctl_chan); 1026 1027 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1028 1029 cctx = xcalloc(1, sizeof(*cctx)); 1030 cctx->rid = rid; 1031 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1032 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1033 1034 /* reply is deferred, sent by mux_session_confirm */ 1035 return 0; 1036} 1037 1038/* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1039static void 1040mux_stdio_confirm(int id, int success, void *arg) 1041{ 1042 struct mux_stdio_confirm_ctx *cctx = arg; 1043 Channel *c, *cc; 1044 Buffer reply; 1045 1046 if (cctx == NULL) 1047 fatal("%s: cctx == NULL", __func__); 1048 if ((c = channel_by_id(id)) == NULL) 1049 fatal("%s: no channel for id %d", __func__, id); 1050 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1051 fatal("%s: channel %d lacks control channel %d", __func__, 1052 id, c->ctl_chan); 1053 1054 if (!success) { 1055 debug3("%s: sending failure reply", __func__); 1056 /* prepare reply */ 1057 buffer_init(&reply); 1058 buffer_put_int(&reply, MUX_S_FAILURE); 1059 buffer_put_int(&reply, cctx->rid); 1060 buffer_put_cstring(&reply, "Session open refused by peer"); 1061 goto done; 1062 } 1063 1064 debug3("%s: sending success reply", __func__); 1065 /* prepare reply */ 1066 buffer_init(&reply); 1067 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1068 buffer_put_int(&reply, cctx->rid); 1069 buffer_put_int(&reply, c->self); 1070 1071 done: 1072 /* Send reply */ 1073 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1074 buffer_free(&reply); 1075 1076 if (cc->mux_pause <= 0) 1077 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1078 cc->mux_pause = 0; /* start processing messages again */ 1079 c->open_confirm_ctx = NULL; 1080 free(cctx); 1081} 1082 1083static int 1084process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1085{ 1086 debug("%s: channel %d: stop listening", __func__, c->self); 1087 1088 if (options.control_master == SSHCTL_MASTER_ASK || 1089 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1090 if (!ask_permission("Disable further multiplexing on shared " 1091 "connection to %s? ", host)) { 1092 debug2("%s: stop listen refused by user", __func__); 1093 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1094 buffer_put_int(r, rid); 1095 buffer_put_cstring(r, "Permission denied"); 1096 return 0; 1097 } 1098 } 1099 1100 if (mux_listener_channel != NULL) { 1101 channel_free(mux_listener_channel); 1102 client_stop_mux(); 1103 free(options.control_path); 1104 options.control_path = NULL; 1105 mux_listener_channel = NULL; 1106 muxserver_sock = -1; 1107 } 1108 1109 /* prepare reply */ 1110 buffer_put_int(r, MUX_S_OK); 1111 buffer_put_int(r, rid); 1112 1113 return 0; 1114} 1115 1116/* Channel callbacks fired on read/write from mux slave fd */ 1117static int 1118mux_master_read_cb(Channel *c) 1119{ 1120 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1121 Buffer in, out; 1122 const u_char *ptr; 1123 u_int type, rid, have, i; 1124 int ret = -1; 1125 1126 /* Setup ctx and */ 1127 if (c->mux_ctx == NULL) { 1128 state = xcalloc(1, sizeof(*state)); 1129 c->mux_ctx = state; 1130 channel_register_cleanup(c->self, 1131 mux_master_control_cleanup_cb, 0); 1132 1133 /* Send hello */ 1134 buffer_init(&out); 1135 buffer_put_int(&out, MUX_MSG_HELLO); 1136 buffer_put_int(&out, SSHMUX_VER); 1137 /* no extensions */ 1138 buffer_put_string(&c->output, buffer_ptr(&out), 1139 buffer_len(&out)); 1140 buffer_free(&out); 1141 debug3("%s: channel %d: hello sent", __func__, c->self); 1142 return 0; 1143 } 1144 1145 buffer_init(&in); 1146 buffer_init(&out); 1147 1148 /* Channel code ensures that we receive whole packets */ 1149 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1150 malf: 1151 error("%s: malformed message", __func__); 1152 goto out; 1153 } 1154 buffer_append(&in, ptr, have); 1155 1156 if (buffer_get_int_ret(&type, &in) != 0) 1157 goto malf; 1158 debug3("%s: channel %d packet type 0x%08x len %u", 1159 __func__, c->self, type, buffer_len(&in)); 1160 1161 if (type == MUX_MSG_HELLO) 1162 rid = 0; 1163 else { 1164 if (!state->hello_rcvd) { 1165 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1166 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1167 goto out; 1168 } 1169 if (buffer_get_int_ret(&rid, &in) != 0) 1170 goto malf; 1171 } 1172 1173 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1174 if (type == mux_master_handlers[i].type) { 1175 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1176 break; 1177 } 1178 } 1179 if (mux_master_handlers[i].handler == NULL) { 1180 error("%s: unsupported mux message 0x%08x", __func__, type); 1181 buffer_put_int(&out, MUX_S_FAILURE); 1182 buffer_put_int(&out, rid); 1183 buffer_put_cstring(&out, "unsupported request"); 1184 ret = 0; 1185 } 1186 /* Enqueue reply packet */ 1187 if (buffer_len(&out) != 0) { 1188 buffer_put_string(&c->output, buffer_ptr(&out), 1189 buffer_len(&out)); 1190 } 1191 out: 1192 buffer_free(&in); 1193 buffer_free(&out); 1194 return ret; 1195} 1196 1197void 1198mux_exit_message(Channel *c, int exitval) 1199{ 1200 Buffer m; 1201 Channel *mux_chan; 1202 1203 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1204 exitval); 1205 1206 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1207 fatal("%s: channel %d missing mux channel %d", 1208 __func__, c->self, c->ctl_chan); 1209 1210 /* Append exit message packet to control socket output queue */ 1211 buffer_init(&m); 1212 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1213 buffer_put_int(&m, c->self); 1214 buffer_put_int(&m, exitval); 1215 1216 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1217 buffer_free(&m); 1218} 1219 1220void 1221mux_tty_alloc_failed(Channel *c) 1222{ 1223 Buffer m; 1224 Channel *mux_chan; 1225 1226 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1227 1228 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1229 fatal("%s: channel %d missing mux channel %d", 1230 __func__, c->self, c->ctl_chan); 1231 1232 /* Append exit message packet to control socket output queue */ 1233 buffer_init(&m); 1234 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1235 buffer_put_int(&m, c->self); 1236 1237 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1238 buffer_free(&m); 1239} 1240 1241/* Prepare a mux master to listen on a Unix domain socket. */ 1242void 1243muxserver_listen(void) 1244{ 1245 mode_t old_umask; 1246 char *orig_control_path = options.control_path; 1247 char rbuf[16+1]; 1248 u_int i, r; 1249 int oerrno; 1250 1251 if (options.control_path == NULL || 1252 options.control_master == SSHCTL_MASTER_NO) 1253 return; 1254 1255 debug("setting up multiplex master socket"); 1256 1257 /* 1258 * Use a temporary path before listen so we can pseudo-atomically 1259 * establish the listening socket in its final location to avoid 1260 * other processes racing in between bind() and listen() and hitting 1261 * an unready socket. 1262 */ 1263 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1264 r = arc4random_uniform(26+26+10); 1265 rbuf[i] = (r < 26) ? 'a' + r : 1266 (r < 26*2) ? 'A' + r - 26 : 1267 '0' + r - 26 - 26; 1268 } 1269 rbuf[sizeof(rbuf) - 1] = '\0'; 1270 options.control_path = NULL; 1271 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1272 debug3("%s: temporary control path %s", __func__, options.control_path); 1273 1274 old_umask = umask(0177); 1275 muxserver_sock = unix_listener(options.control_path, 64, 0); 1276 oerrno = errno; 1277 umask(old_umask); 1278 if (muxserver_sock < 0) { 1279 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1280 error("ControlSocket %s already exists, " 1281 "disabling multiplexing", options.control_path); 1282 disable_mux_master: 1283 if (muxserver_sock != -1) { 1284 close(muxserver_sock); 1285 muxserver_sock = -1; 1286 } 1287 free(orig_control_path); 1288 free(options.control_path); 1289 options.control_path = NULL; 1290 options.control_master = SSHCTL_MASTER_NO; 1291 return; 1292 } else { 1293 /* unix_listener() logs the error */ 1294 cleanup_exit(255); 1295 } 1296 } 1297 1298 /* Now atomically "move" the mux socket into position */ 1299 if (link(options.control_path, orig_control_path) != 0) { 1300 if (errno != EEXIST) { 1301 fatal("%s: link mux listener %s => %s: %s", __func__, 1302 options.control_path, orig_control_path, 1303 strerror(errno)); 1304 } 1305 error("ControlSocket %s already exists, disabling multiplexing", 1306 orig_control_path); 1307 unlink(options.control_path); 1308 goto disable_mux_master; 1309 } 1310 unlink(options.control_path); 1311 free(options.control_path); 1312 options.control_path = orig_control_path; 1313 1314 set_nonblock(muxserver_sock); 1315 1316 mux_listener_channel = channel_new("mux listener", 1317 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1318 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1319 0, options.control_path, 1); 1320 mux_listener_channel->mux_rcb = mux_master_read_cb; 1321 debug3("%s: mux listener channel %d fd %d", __func__, 1322 mux_listener_channel->self, mux_listener_channel->sock); 1323} 1324 1325/* Callback on open confirmation in mux master for a mux client session. */ 1326static void 1327mux_session_confirm(int id, int success, void *arg) 1328{ 1329 struct mux_session_confirm_ctx *cctx = arg; 1330 const char *display; 1331 Channel *c, *cc; 1332 int i; 1333 Buffer reply; 1334 1335 if (cctx == NULL) 1336 fatal("%s: cctx == NULL", __func__); 1337 if ((c = channel_by_id(id)) == NULL) 1338 fatal("%s: no channel for id %d", __func__, id); 1339 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1340 fatal("%s: channel %d lacks control channel %d", __func__, 1341 id, c->ctl_chan); 1342 1343 if (!success) { 1344 debug3("%s: sending failure reply", __func__); 1345 /* prepare reply */ 1346 buffer_init(&reply); 1347 buffer_put_int(&reply, MUX_S_FAILURE); 1348 buffer_put_int(&reply, cctx->rid); 1349 buffer_put_cstring(&reply, "Session open refused by peer"); 1350 goto done; 1351 } 1352 1353 display = getenv("DISPLAY"); 1354 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1355 char *proto, *data; 1356 1357 /* Get reasonable local authentication information. */ 1358 if (client_x11_get_proto(display, options.xauth_location, 1359 options.forward_x11_trusted, options.forward_x11_timeout, 1360 &proto, &data) == 0) { 1361 /* Request forwarding with authentication spoofing. */ 1362 debug("Requesting X11 forwarding with authentication " 1363 "spoofing."); 1364 x11_request_forwarding_with_spoofing(id, display, proto, 1365 data, 1); 1366 /* XXX exit_on_forward_failure */ 1367 client_expect_confirm(id, "X11 forwarding", 1368 CONFIRM_WARN); 1369 } 1370 } 1371 1372 if (cctx->want_agent_fwd && options.forward_agent) { 1373 debug("Requesting authentication agent forwarding."); 1374 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1375 packet_send(); 1376 } 1377 1378 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1379 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1380 1381 debug3("%s: sending success reply", __func__); 1382 /* prepare reply */ 1383 buffer_init(&reply); 1384 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1385 buffer_put_int(&reply, cctx->rid); 1386 buffer_put_int(&reply, c->self); 1387 1388 done: 1389 /* Send reply */ 1390 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1391 buffer_free(&reply); 1392 1393 if (cc->mux_pause <= 0) 1394 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1395 cc->mux_pause = 0; /* start processing messages again */ 1396 c->open_confirm_ctx = NULL; 1397 buffer_free(&cctx->cmd); 1398 free(cctx->term); 1399 if (cctx->env != NULL) { 1400 for (i = 0; cctx->env[i] != NULL; i++) 1401 free(cctx->env[i]); 1402 free(cctx->env); 1403 } 1404 free(cctx); 1405} 1406 1407/* ** Multiplexing client support */ 1408 1409/* Exit signal handler */ 1410static void 1411control_client_sighandler(int signo) 1412{ 1413 muxclient_terminate = signo; 1414} 1415 1416/* 1417 * Relay signal handler - used to pass some signals from mux client to 1418 * mux master. 1419 */ 1420static void 1421control_client_sigrelay(int signo) 1422{ 1423 int save_errno = errno; 1424 1425 if (muxserver_pid > 1) 1426 kill(muxserver_pid, signo); 1427 1428 errno = save_errno; 1429} 1430 1431static int 1432mux_client_read(int fd, Buffer *b, u_int need) 1433{ 1434 u_int have; 1435 ssize_t len; 1436 u_char *p; 1437 struct pollfd pfd; 1438 1439 pfd.fd = fd; 1440 pfd.events = POLLIN; 1441 p = buffer_append_space(b, need); 1442 for (have = 0; have < need; ) { 1443 if (muxclient_terminate) { 1444 errno = EINTR; 1445 return -1; 1446 } 1447 len = read(fd, p + have, need - have); 1448 if (len < 0) { 1449 switch (errno) { 1450#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1451 case EWOULDBLOCK: 1452#endif 1453 case EAGAIN: 1454 (void)poll(&pfd, 1, -1); 1455 /* FALLTHROUGH */ 1456 case EINTR: 1457 continue; 1458 default: 1459 return -1; 1460 } 1461 } 1462 if (len == 0) { 1463 errno = EPIPE; 1464 return -1; 1465 } 1466 have += (u_int)len; 1467 } 1468 return 0; 1469} 1470 1471static int 1472mux_client_write_packet(int fd, Buffer *m) 1473{ 1474 Buffer queue; 1475 u_int have, need; 1476 int oerrno, len; 1477 u_char *ptr; 1478 struct pollfd pfd; 1479 1480 pfd.fd = fd; 1481 pfd.events = POLLOUT; 1482 buffer_init(&queue); 1483 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1484 1485 need = buffer_len(&queue); 1486 ptr = buffer_ptr(&queue); 1487 1488 for (have = 0; have < need; ) { 1489 if (muxclient_terminate) { 1490 buffer_free(&queue); 1491 errno = EINTR; 1492 return -1; 1493 } 1494 len = write(fd, ptr + have, need - have); 1495 if (len < 0) { 1496 switch (errno) { 1497#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1498 case EWOULDBLOCK: 1499#endif 1500 case EAGAIN: 1501 (void)poll(&pfd, 1, -1); 1502 /* FALLTHROUGH */ 1503 case EINTR: 1504 continue; 1505 default: 1506 oerrno = errno; 1507 buffer_free(&queue); 1508 errno = oerrno; 1509 return -1; 1510 } 1511 } 1512 if (len == 0) { 1513 buffer_free(&queue); 1514 errno = EPIPE; 1515 return -1; 1516 } 1517 have += (u_int)len; 1518 } 1519 buffer_free(&queue); 1520 return 0; 1521} 1522 1523static int 1524mux_client_read_packet(int fd, Buffer *m) 1525{ 1526 Buffer queue; 1527 u_int need, have; 1528 const u_char *ptr; 1529 int oerrno; 1530 1531 buffer_init(&queue); 1532 if (mux_client_read(fd, &queue, 4) != 0) { 1533 if ((oerrno = errno) == EPIPE) 1534 debug3("%s: read header failed: %s", __func__, 1535 strerror(errno)); 1536 buffer_free(&queue); 1537 errno = oerrno; 1538 return -1; 1539 } 1540 need = get_u32(buffer_ptr(&queue)); 1541 if (mux_client_read(fd, &queue, need) != 0) { 1542 oerrno = errno; 1543 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1544 buffer_free(&queue); 1545 errno = oerrno; 1546 return -1; 1547 } 1548 ptr = buffer_get_string_ptr(&queue, &have); 1549 buffer_append(m, ptr, have); 1550 buffer_free(&queue); 1551 return 0; 1552} 1553 1554static int 1555mux_client_hello_exchange(int fd) 1556{ 1557 Buffer m; 1558 u_int type, ver; 1559 1560 buffer_init(&m); 1561 buffer_put_int(&m, MUX_MSG_HELLO); 1562 buffer_put_int(&m, SSHMUX_VER); 1563 /* no extensions */ 1564 1565 if (mux_client_write_packet(fd, &m) != 0) 1566 fatal("%s: write packet: %s", __func__, strerror(errno)); 1567 1568 buffer_clear(&m); 1569 1570 /* Read their HELLO */ 1571 if (mux_client_read_packet(fd, &m) != 0) { 1572 buffer_free(&m); 1573 return -1; 1574 } 1575 1576 type = buffer_get_int(&m); 1577 if (type != MUX_MSG_HELLO) 1578 fatal("%s: expected HELLO (%u) received %u", 1579 __func__, MUX_MSG_HELLO, type); 1580 ver = buffer_get_int(&m); 1581 if (ver != SSHMUX_VER) 1582 fatal("Unsupported multiplexing protocol version %d " 1583 "(expected %d)", ver, SSHMUX_VER); 1584 debug2("%s: master version %u", __func__, ver); 1585 /* No extensions are presently defined */ 1586 while (buffer_len(&m) > 0) { 1587 char *name = buffer_get_string(&m, NULL); 1588 char *value = buffer_get_string(&m, NULL); 1589 1590 debug2("Unrecognised master extension \"%s\"", name); 1591 free(name); 1592 free(value); 1593 } 1594 buffer_free(&m); 1595 return 0; 1596} 1597 1598static u_int 1599mux_client_request_alive(int fd) 1600{ 1601 Buffer m; 1602 char *e; 1603 u_int pid, type, rid; 1604 1605 debug3("%s: entering", __func__); 1606 1607 buffer_init(&m); 1608 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1609 buffer_put_int(&m, muxclient_request_id); 1610 1611 if (mux_client_write_packet(fd, &m) != 0) 1612 fatal("%s: write packet: %s", __func__, strerror(errno)); 1613 1614 buffer_clear(&m); 1615 1616 /* Read their reply */ 1617 if (mux_client_read_packet(fd, &m) != 0) { 1618 buffer_free(&m); 1619 return 0; 1620 } 1621 1622 type = buffer_get_int(&m); 1623 if (type != MUX_S_ALIVE) { 1624 e = buffer_get_string(&m, NULL); 1625 fatal("%s: master returned error: %s", __func__, e); 1626 } 1627 1628 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1629 fatal("%s: out of sequence reply: my id %u theirs %u", 1630 __func__, muxclient_request_id, rid); 1631 pid = buffer_get_int(&m); 1632 buffer_free(&m); 1633 1634 debug3("%s: done pid = %u", __func__, pid); 1635 1636 muxclient_request_id++; 1637 1638 return pid; 1639} 1640 1641static void 1642mux_client_request_terminate(int fd) 1643{ 1644 Buffer m; 1645 char *e; 1646 u_int type, rid; 1647 1648 debug3("%s: entering", __func__); 1649 1650 buffer_init(&m); 1651 buffer_put_int(&m, MUX_C_TERMINATE); 1652 buffer_put_int(&m, muxclient_request_id); 1653 1654 if (mux_client_write_packet(fd, &m) != 0) 1655 fatal("%s: write packet: %s", __func__, strerror(errno)); 1656 1657 buffer_clear(&m); 1658 1659 /* Read their reply */ 1660 if (mux_client_read_packet(fd, &m) != 0) { 1661 /* Remote end exited already */ 1662 if (errno == EPIPE) { 1663 buffer_free(&m); 1664 return; 1665 } 1666 fatal("%s: read from master failed: %s", 1667 __func__, strerror(errno)); 1668 } 1669 1670 type = buffer_get_int(&m); 1671 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1672 fatal("%s: out of sequence reply: my id %u theirs %u", 1673 __func__, muxclient_request_id, rid); 1674 switch (type) { 1675 case MUX_S_OK: 1676 break; 1677 case MUX_S_PERMISSION_DENIED: 1678 e = buffer_get_string(&m, NULL); 1679 fatal("Master refused termination request: %s", e); 1680 case MUX_S_FAILURE: 1681 e = buffer_get_string(&m, NULL); 1682 fatal("%s: termination request failed: %s", __func__, e); 1683 default: 1684 fatal("%s: unexpected response from master 0x%08x", 1685 __func__, type); 1686 } 1687 buffer_free(&m); 1688 muxclient_request_id++; 1689} 1690 1691static int 1692mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1693{ 1694 Buffer m; 1695 char *e, *fwd_desc; 1696 u_int type, rid; 1697 1698 fwd_desc = format_forward(ftype, fwd); 1699 debug("Requesting %s %s", 1700 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1701 free(fwd_desc); 1702 1703 buffer_init(&m); 1704 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1705 buffer_put_int(&m, muxclient_request_id); 1706 buffer_put_int(&m, ftype); 1707 if (fwd->listen_path != NULL) { 1708 buffer_put_cstring(&m, fwd->listen_path); 1709 } else { 1710 buffer_put_cstring(&m, 1711 fwd->listen_host == NULL ? "" : 1712 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1713 } 1714 buffer_put_int(&m, fwd->listen_port); 1715 if (fwd->connect_path != NULL) { 1716 buffer_put_cstring(&m, fwd->connect_path); 1717 } else { 1718 buffer_put_cstring(&m, 1719 fwd->connect_host == NULL ? "" : fwd->connect_host); 1720 } 1721 buffer_put_int(&m, fwd->connect_port); 1722 1723 if (mux_client_write_packet(fd, &m) != 0) 1724 fatal("%s: write packet: %s", __func__, strerror(errno)); 1725 1726 buffer_clear(&m); 1727 1728 /* Read their reply */ 1729 if (mux_client_read_packet(fd, &m) != 0) { 1730 buffer_free(&m); 1731 return -1; 1732 } 1733 1734 type = buffer_get_int(&m); 1735 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1736 fatal("%s: out of sequence reply: my id %u theirs %u", 1737 __func__, muxclient_request_id, rid); 1738 switch (type) { 1739 case MUX_S_OK: 1740 break; 1741 case MUX_S_REMOTE_PORT: 1742 if (cancel_flag) 1743 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1744 fwd->allocated_port = buffer_get_int(&m); 1745 verbose("Allocated port %u for remote forward to %s:%d", 1746 fwd->allocated_port, 1747 fwd->connect_host ? fwd->connect_host : "", 1748 fwd->connect_port); 1749 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1750 fprintf(stdout, "%i\n", fwd->allocated_port); 1751 break; 1752 case MUX_S_PERMISSION_DENIED: 1753 e = buffer_get_string(&m, NULL); 1754 buffer_free(&m); 1755 error("Master refused forwarding request: %s", e); 1756 return -1; 1757 case MUX_S_FAILURE: 1758 e = buffer_get_string(&m, NULL); 1759 buffer_free(&m); 1760 error("%s: forwarding request failed: %s", __func__, e); 1761 return -1; 1762 default: 1763 fatal("%s: unexpected response from master 0x%08x", 1764 __func__, type); 1765 } 1766 buffer_free(&m); 1767 1768 muxclient_request_id++; 1769 return 0; 1770} 1771 1772static int 1773mux_client_forwards(int fd, int cancel_flag) 1774{ 1775 int i, ret = 0; 1776 1777 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1778 cancel_flag ? "cancel" : "request", 1779 options.num_local_forwards, options.num_remote_forwards); 1780 1781 /* XXX ExitOnForwardingFailure */ 1782 for (i = 0; i < options.num_local_forwards; i++) { 1783 if (mux_client_forward(fd, cancel_flag, 1784 options.local_forwards[i].connect_port == 0 ? 1785 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1786 options.local_forwards + i) != 0) 1787 ret = -1; 1788 } 1789 for (i = 0; i < options.num_remote_forwards; i++) { 1790 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1791 options.remote_forwards + i) != 0) 1792 ret = -1; 1793 } 1794 return ret; 1795} 1796 1797static int 1798mux_client_request_session(int fd) 1799{ 1800 Buffer m; 1801 char *e, *term; 1802 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1803 extern char **environ; 1804 int devnull, rawmode; 1805 1806 debug3("%s: entering", __func__); 1807 1808 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1809 error("%s: master alive request failed", __func__); 1810 return -1; 1811 } 1812 1813 signal(SIGPIPE, SIG_IGN); 1814 1815 if (stdin_null_flag) { 1816 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1817 fatal("open(/dev/null): %s", strerror(errno)); 1818 if (dup2(devnull, STDIN_FILENO) == -1) 1819 fatal("dup2: %s", strerror(errno)); 1820 if (devnull > STDERR_FILENO) 1821 close(devnull); 1822 } 1823 1824 term = getenv("TERM"); 1825 1826 buffer_init(&m); 1827 buffer_put_int(&m, MUX_C_NEW_SESSION); 1828 buffer_put_int(&m, muxclient_request_id); 1829 buffer_put_cstring(&m, ""); /* reserved */ 1830 buffer_put_int(&m, tty_flag); 1831 buffer_put_int(&m, options.forward_x11); 1832 buffer_put_int(&m, options.forward_agent); 1833 buffer_put_int(&m, subsystem_flag); 1834 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1835 0xffffffff : (u_int)options.escape_char); 1836 buffer_put_cstring(&m, term == NULL ? "" : term); 1837 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1838 1839 if (options.num_send_env > 0 && environ != NULL) { 1840 /* Pass environment */ 1841 for (i = 0; environ[i] != NULL; i++) { 1842 if (env_permitted(environ[i])) { 1843 buffer_put_cstring(&m, environ[i]); 1844 } 1845 } 1846 } 1847 1848 if (mux_client_write_packet(fd, &m) != 0) 1849 fatal("%s: write packet: %s", __func__, strerror(errno)); 1850 1851 /* Send the stdio file descriptors */ 1852 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1853 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1854 mm_send_fd(fd, STDERR_FILENO) == -1) 1855 fatal("%s: send fds failed", __func__); 1856 1857 debug3("%s: session request sent", __func__); 1858 1859 /* Read their reply */ 1860 buffer_clear(&m); 1861 if (mux_client_read_packet(fd, &m) != 0) { 1862 error("%s: read from master failed: %s", 1863 __func__, strerror(errno)); 1864 buffer_free(&m); 1865 return -1; 1866 } 1867 1868 type = buffer_get_int(&m); 1869 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1870 fatal("%s: out of sequence reply: my id %u theirs %u", 1871 __func__, muxclient_request_id, rid); 1872 switch (type) { 1873 case MUX_S_SESSION_OPENED: 1874 sid = buffer_get_int(&m); 1875 debug("%s: master session id: %u", __func__, sid); 1876 break; 1877 case MUX_S_PERMISSION_DENIED: 1878 e = buffer_get_string(&m, NULL); 1879 buffer_free(&m); 1880 error("Master refused session request: %s", e); 1881 return -1; 1882 case MUX_S_FAILURE: 1883 e = buffer_get_string(&m, NULL); 1884 buffer_free(&m); 1885 error("%s: session request failed: %s", __func__, e); 1886 return -1; 1887 default: 1888 buffer_free(&m); 1889 error("%s: unexpected response from master 0x%08x", 1890 __func__, type); 1891 return -1; 1892 } 1893 muxclient_request_id++; 1894 1895 if (pledge("stdio proc tty", NULL) == -1) 1896 fatal("%s pledge(): %s", __func__, strerror(errno)); 1897 platform_pledge_mux(); 1898 1899 signal(SIGHUP, control_client_sighandler); 1900 signal(SIGINT, control_client_sighandler); 1901 signal(SIGTERM, control_client_sighandler); 1902 signal(SIGWINCH, control_client_sigrelay); 1903 1904 rawmode = tty_flag; 1905 if (tty_flag) 1906 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1907 1908 /* 1909 * Stick around until the controlee closes the client_fd. 1910 * Before it does, it is expected to write an exit message. 1911 * This process must read the value and wait for the closure of 1912 * the client_fd; if this one closes early, the multiplex master will 1913 * terminate early too (possibly losing data). 1914 */ 1915 for (exitval = 255, exitval_seen = 0;;) { 1916 buffer_clear(&m); 1917 if (mux_client_read_packet(fd, &m) != 0) 1918 break; 1919 type = buffer_get_int(&m); 1920 switch (type) { 1921 case MUX_S_TTY_ALLOC_FAIL: 1922 if ((esid = buffer_get_int(&m)) != sid) 1923 fatal("%s: tty alloc fail on unknown session: " 1924 "my id %u theirs %u", 1925 __func__, sid, esid); 1926 leave_raw_mode(options.request_tty == 1927 REQUEST_TTY_FORCE); 1928 rawmode = 0; 1929 continue; 1930 case MUX_S_EXIT_MESSAGE: 1931 if ((esid = buffer_get_int(&m)) != sid) 1932 fatal("%s: exit on unknown session: " 1933 "my id %u theirs %u", 1934 __func__, sid, esid); 1935 if (exitval_seen) 1936 fatal("%s: exitval sent twice", __func__); 1937 exitval = buffer_get_int(&m); 1938 exitval_seen = 1; 1939 continue; 1940 default: 1941 e = buffer_get_string(&m, NULL); 1942 fatal("%s: master returned error: %s", __func__, e); 1943 } 1944 } 1945 1946 close(fd); 1947 if (rawmode) 1948 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1949 1950 if (muxclient_terminate) { 1951 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1952 exitval = 255; 1953 } else if (!exitval_seen) { 1954 debug2("Control master terminated unexpectedly"); 1955 exitval = 255; 1956 } else 1957 debug2("Received exit status from master %d", exitval); 1958 1959 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1960 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1961 1962 exit(exitval); 1963} 1964 1965static int 1966mux_client_request_stdio_fwd(int fd) 1967{ 1968 Buffer m; 1969 char *e; 1970 u_int type, rid, sid; 1971 int devnull; 1972 1973 debug3("%s: entering", __func__); 1974 1975 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1976 error("%s: master alive request failed", __func__); 1977 return -1; 1978 } 1979 1980 signal(SIGPIPE, SIG_IGN); 1981 1982 if (stdin_null_flag) { 1983 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1984 fatal("open(/dev/null): %s", strerror(errno)); 1985 if (dup2(devnull, STDIN_FILENO) == -1) 1986 fatal("dup2: %s", strerror(errno)); 1987 if (devnull > STDERR_FILENO) 1988 close(devnull); 1989 } 1990 1991 buffer_init(&m); 1992 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1993 buffer_put_int(&m, muxclient_request_id); 1994 buffer_put_cstring(&m, ""); /* reserved */ 1995 buffer_put_cstring(&m, stdio_forward_host); 1996 buffer_put_int(&m, stdio_forward_port); 1997 1998 if (mux_client_write_packet(fd, &m) != 0) 1999 fatal("%s: write packet: %s", __func__, strerror(errno)); 2000 2001 /* Send the stdio file descriptors */ 2002 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2003 mm_send_fd(fd, STDOUT_FILENO) == -1) 2004 fatal("%s: send fds failed", __func__); 2005 2006 if (pledge("stdio proc tty", NULL) == -1) 2007 fatal("%s pledge(): %s", __func__, strerror(errno)); 2008 platform_pledge_mux(); 2009 2010 debug3("%s: stdio forward request sent", __func__); 2011 2012 /* Read their reply */ 2013 buffer_clear(&m); 2014 2015 if (mux_client_read_packet(fd, &m) != 0) { 2016 error("%s: read from master failed: %s", 2017 __func__, strerror(errno)); 2018 buffer_free(&m); 2019 return -1; 2020 } 2021 2022 type = buffer_get_int(&m); 2023 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2024 fatal("%s: out of sequence reply: my id %u theirs %u", 2025 __func__, muxclient_request_id, rid); 2026 switch (type) { 2027 case MUX_S_SESSION_OPENED: 2028 sid = buffer_get_int(&m); 2029 debug("%s: master session id: %u", __func__, sid); 2030 break; 2031 case MUX_S_PERMISSION_DENIED: 2032 e = buffer_get_string(&m, NULL); 2033 buffer_free(&m); 2034 fatal("Master refused stdio forwarding request: %s", e); 2035 case MUX_S_FAILURE: 2036 e = buffer_get_string(&m, NULL); 2037 buffer_free(&m); 2038 fatal("Stdio forwarding request failed: %s", e); 2039 default: 2040 buffer_free(&m); 2041 error("%s: unexpected response from master 0x%08x", 2042 __func__, type); 2043 return -1; 2044 } 2045 muxclient_request_id++; 2046 2047 signal(SIGHUP, control_client_sighandler); 2048 signal(SIGINT, control_client_sighandler); 2049 signal(SIGTERM, control_client_sighandler); 2050 signal(SIGWINCH, control_client_sigrelay); 2051 2052 /* 2053 * Stick around until the controlee closes the client_fd. 2054 */ 2055 buffer_clear(&m); 2056 if (mux_client_read_packet(fd, &m) != 0) { 2057 if (errno == EPIPE || 2058 (errno == EINTR && muxclient_terminate != 0)) 2059 return 0; 2060 fatal("%s: mux_client_read_packet: %s", 2061 __func__, strerror(errno)); 2062 } 2063 fatal("%s: master returned unexpected message %u", __func__, type); 2064} 2065 2066static void 2067mux_client_request_stop_listening(int fd) 2068{ 2069 Buffer m; 2070 char *e; 2071 u_int type, rid; 2072 2073 debug3("%s: entering", __func__); 2074 2075 buffer_init(&m); 2076 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2077 buffer_put_int(&m, muxclient_request_id); 2078 2079 if (mux_client_write_packet(fd, &m) != 0) 2080 fatal("%s: write packet: %s", __func__, strerror(errno)); 2081 2082 buffer_clear(&m); 2083 2084 /* Read their reply */ 2085 if (mux_client_read_packet(fd, &m) != 0) 2086 fatal("%s: read from master failed: %s", 2087 __func__, strerror(errno)); 2088 2089 type = buffer_get_int(&m); 2090 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2091 fatal("%s: out of sequence reply: my id %u theirs %u", 2092 __func__, muxclient_request_id, rid); 2093 switch (type) { 2094 case MUX_S_OK: 2095 break; 2096 case MUX_S_PERMISSION_DENIED: 2097 e = buffer_get_string(&m, NULL); 2098 fatal("Master refused stop listening request: %s", e); 2099 case MUX_S_FAILURE: 2100 e = buffer_get_string(&m, NULL); 2101 fatal("%s: stop listening request failed: %s", __func__, e); 2102 default: 2103 fatal("%s: unexpected response from master 0x%08x", 2104 __func__, type); 2105 } 2106 buffer_free(&m); 2107 muxclient_request_id++; 2108} 2109 2110/* Multiplex client main loop. */ 2111void 2112muxclient(const char *path) 2113{ 2114 struct sockaddr_un addr; 2115 socklen_t sun_len; 2116 int sock; 2117 u_int pid; 2118 2119 if (muxclient_command == 0) { 2120 if (stdio_forward_host != NULL) 2121 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2122 else 2123 muxclient_command = SSHMUX_COMMAND_OPEN; 2124 } 2125 2126 switch (options.control_master) { 2127 case SSHCTL_MASTER_AUTO: 2128 case SSHCTL_MASTER_AUTO_ASK: 2129 debug("auto-mux: Trying existing master"); 2130 /* FALLTHROUGH */ 2131 case SSHCTL_MASTER_NO: 2132 break; 2133 default: 2134 return; 2135 } 2136 2137 memset(&addr, '\0', sizeof(addr)); 2138 addr.sun_family = AF_UNIX; 2139 sun_len = offsetof(struct sockaddr_un, sun_path) + 2140 strlen(path) + 1; 2141 2142 if (strlcpy(addr.sun_path, path, 2143 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2144 fatal("ControlPath too long"); 2145 2146 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2147 fatal("%s socket(): %s", __func__, strerror(errno)); 2148 2149 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2150 switch (muxclient_command) { 2151 case SSHMUX_COMMAND_OPEN: 2152 case SSHMUX_COMMAND_STDIO_FWD: 2153 break; 2154 default: 2155 fatal("Control socket connect(%.100s): %s", path, 2156 strerror(errno)); 2157 } 2158 if (errno == ECONNREFUSED && 2159 options.control_master != SSHCTL_MASTER_NO) { 2160 debug("Stale control socket %.100s, unlinking", path); 2161 unlink(path); 2162 } else if (errno == ENOENT) { 2163 debug("Control socket \"%.100s\" does not exist", path); 2164 } else { 2165 error("Control socket connect(%.100s): %s", path, 2166 strerror(errno)); 2167 } 2168 close(sock); 2169 return; 2170 } 2171 set_nonblock(sock); 2172 2173 if (mux_client_hello_exchange(sock) != 0) { 2174 error("%s: master hello exchange failed", __func__); 2175 close(sock); 2176 return; 2177 } 2178 2179 switch (muxclient_command) { 2180 case SSHMUX_COMMAND_ALIVE_CHECK: 2181 if ((pid = mux_client_request_alive(sock)) == 0) 2182 fatal("%s: master alive check failed", __func__); 2183 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2184 exit(0); 2185 case SSHMUX_COMMAND_TERMINATE: 2186 mux_client_request_terminate(sock); 2187 fprintf(stderr, "Exit request sent.\r\n"); 2188 exit(0); 2189 case SSHMUX_COMMAND_FORWARD: 2190 if (mux_client_forwards(sock, 0) != 0) 2191 fatal("%s: master forward request failed", __func__); 2192 exit(0); 2193 case SSHMUX_COMMAND_OPEN: 2194 if (mux_client_forwards(sock, 0) != 0) { 2195 error("%s: master forward request failed", __func__); 2196 return; 2197 } 2198 mux_client_request_session(sock); 2199 return; 2200 case SSHMUX_COMMAND_STDIO_FWD: 2201 mux_client_request_stdio_fwd(sock); 2202 exit(0); 2203 case SSHMUX_COMMAND_STOP: 2204 mux_client_request_stop_listening(sock); 2205 fprintf(stderr, "Stop listening request sent.\r\n"); 2206 exit(0); 2207 case SSHMUX_COMMAND_CANCEL_FWD: 2208 if (mux_client_forwards(sock, 1) != 0) 2209 error("%s: master cancel forward request failed", 2210 __func__); 2211 exit(0); 2212 default: 2213 fatal("unrecognised muxclient_command %d", muxclient_command); 2214 } 2215} 2216