1 /* $OpenBSD: mux.c,v 1.53 2015/05/01 04:03:20 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("$FreeBSD$"); 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 */ 85 extern int tty_flag; 86 extern Options options; 87 extern int stdin_null_flag; 88 extern char *host; 89 extern int subsystem_flag; 90 extern Buffer command; 91 extern volatile sig_atomic_t quit_pending; 92 extern char *stdio_forward_host; 93 extern int stdio_forward_port; 94 95 /* Context for session open confirmation callback */ 96 struct 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 */ 109 struct mux_stdio_confirm_ctx { 110 u_int rid; 111 }; 112 113 /* Context for global channel callback */ 114 struct 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 */ 121 int muxserver_sock = -1; 122 123 /* client request id */ 124 u_int muxclient_request_id = 0; 125 126 /* Multiplexing control command */ 127 u_int muxclient_command = 0; 128 129 /* Set when signalled. */ 130 static volatile sig_atomic_t muxclient_terminate = 0; 131 132 /* PID of multiplex server */ 133 static u_int muxserver_pid = 0; 134 135 static Channel *mux_listener_channel = NULL; 136 137 struct 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 3 163 164 static void mux_session_confirm(int, int, void *); 165 static void mux_stdio_confirm(int, int, void *); 166 167 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 168 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 169 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 170 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 171 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 172 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 173 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 174 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 175 176 static 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 */ 193 static void 194 mux_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 */ 214 static void 215 mux_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. */ 243 static int 244 env_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 */ 265 266 static int 267 process_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 } 307 308 static int 309 process_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 } 479 480 static int 481 process_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 } 492 493 static int 494 process_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 } 516 517 static char * 518 format_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 } 552 553 static int 554 compare_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 } 562 563 static int 564 compare_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 } 581 582 static void 583 mux_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 } 658 659 static int 660 process_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 /* 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 } 824 825 static int 826 process_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 if (buffer_get_int_ret(&ftype, m) != 0 || 837 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 838 buffer_get_int_ret(&lport, m) != 0 || 839 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 840 buffer_get_int_ret(&cport, m) != 0 || 841 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 842 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 843 error("%s: malformed message", __func__); 844 ret = -1; 845 goto out; 846 } 847 848 if (*listen_addr == '\0') { 849 free(listen_addr); 850 listen_addr = NULL; 851 } 852 if (*connect_addr == '\0') { 853 free(connect_addr); 854 connect_addr = NULL; 855 } 856 857 memset(&fwd, 0, sizeof(fwd)); 858 fwd.listen_port = lport; 859 if (fwd.listen_port == PORT_STREAMLOCAL) 860 fwd.listen_path = listen_addr; 861 else 862 fwd.listen_host = listen_addr; 863 fwd.connect_port = cport; 864 if (fwd.connect_port == PORT_STREAMLOCAL) 865 fwd.connect_path = connect_addr; 866 else 867 fwd.connect_host = connect_addr; 868 869 debug2("%s: channel %d: request cancel %s", __func__, c->self, 870 (fwd_desc = format_forward(ftype, &fwd))); 871 872 /* make sure this has been requested */ 873 found_fwd = NULL; 874 switch (ftype) { 875 case MUX_FWD_LOCAL: 876 case MUX_FWD_DYNAMIC: 877 for (i = 0; i < options.num_local_forwards; i++) { 878 if (compare_forward(&fwd, 879 options.local_forwards + i)) { 880 found_fwd = options.local_forwards + i; 881 break; 882 } 883 } 884 break; 885 case MUX_FWD_REMOTE: 886 for (i = 0; i < options.num_remote_forwards; i++) { 887 if (compare_forward(&fwd, 888 options.remote_forwards + i)) { 889 found_fwd = options.remote_forwards + i; 890 break; 891 } 892 } 893 break; 894 } 895 896 if (found_fwd == NULL) 897 error_reason = "port not forwarded"; 898 else if (ftype == MUX_FWD_REMOTE) { 899 /* 900 * This shouldn't fail unless we confused the host/port 901 * between options.remote_forwards and permitted_opens. 902 * However, for dynamic allocated listen ports we need 903 * to use the actual listen port. 904 */ 905 if (channel_request_rforward_cancel(found_fwd) == -1) 906 error_reason = "port not in permitted opens"; 907 } else { /* local and dynamic forwards */ 908 /* Ditto */ 909 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 910 &options.fwd_opts) == -1) 911 error_reason = "port not found"; 912 } 913 914 if (error_reason == NULL) { 915 buffer_put_int(r, MUX_S_OK); 916 buffer_put_int(r, rid); 917 918 free(found_fwd->listen_host); 919 free(found_fwd->listen_path); 920 free(found_fwd->connect_host); 921 free(found_fwd->connect_path); 922 found_fwd->listen_host = found_fwd->connect_host = NULL; 923 found_fwd->listen_path = found_fwd->connect_path = NULL; 924 found_fwd->listen_port = found_fwd->connect_port = 0; 925 } else { 926 buffer_put_int(r, MUX_S_FAILURE); 927 buffer_put_int(r, rid); 928 buffer_put_cstring(r, error_reason); 929 } 930 out: 931 free(fwd_desc); 932 free(listen_addr); 933 free(connect_addr); 934 935 return ret; 936 } 937 938 static int 939 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 940 { 941 Channel *nc; 942 char *reserved, *chost; 943 u_int cport, i, j; 944 int new_fd[2]; 945 struct mux_stdio_confirm_ctx *cctx; 946 947 chost = reserved = NULL; 948 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 949 (chost = buffer_get_string_ret(m, NULL)) == NULL || 950 buffer_get_int_ret(&cport, m) != 0) { 951 free(reserved); 952 free(chost); 953 error("%s: malformed message", __func__); 954 return -1; 955 } 956 free(reserved); 957 958 debug2("%s: channel %d: request stdio fwd to %s:%u", 959 __func__, c->self, chost, cport); 960 961 /* Gather fds from client */ 962 for(i = 0; i < 2; i++) { 963 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 964 error("%s: failed to receive fd %d from slave", 965 __func__, i); 966 for (j = 0; j < i; j++) 967 close(new_fd[j]); 968 free(chost); 969 970 /* prepare reply */ 971 buffer_put_int(r, MUX_S_FAILURE); 972 buffer_put_int(r, rid); 973 buffer_put_cstring(r, 974 "did not receive file descriptors"); 975 return -1; 976 } 977 } 978 979 debug3("%s: got fds stdin %d, stdout %d", __func__, 980 new_fd[0], new_fd[1]); 981 982 /* XXX support multiple child sessions in future */ 983 if (c->remote_id != -1) { 984 debug2("%s: session already open", __func__); 985 /* prepare reply */ 986 buffer_put_int(r, MUX_S_FAILURE); 987 buffer_put_int(r, rid); 988 buffer_put_cstring(r, "Multiple sessions not supported"); 989 cleanup: 990 close(new_fd[0]); 991 close(new_fd[1]); 992 free(chost); 993 return 0; 994 } 995 996 if (options.control_master == SSHCTL_MASTER_ASK || 997 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 998 if (!ask_permission("Allow forward to %s:%u? ", 999 chost, cport)) { 1000 debug2("%s: stdio fwd refused by user", __func__); 1001 /* prepare reply */ 1002 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1003 buffer_put_int(r, rid); 1004 buffer_put_cstring(r, "Permission denied"); 1005 goto cleanup; 1006 } 1007 } 1008 1009 /* enable nonblocking unless tty */ 1010 if (!isatty(new_fd[0])) 1011 set_nonblock(new_fd[0]); 1012 if (!isatty(new_fd[1])) 1013 set_nonblock(new_fd[1]); 1014 1015 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1016 1017 nc->ctl_chan = c->self; /* link session -> control channel */ 1018 c->remote_id = nc->self; /* link control -> session channel */ 1019 1020 debug2("%s: channel_new: %d linked to control channel %d", 1021 __func__, nc->self, nc->ctl_chan); 1022 1023 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1024 1025 cctx = xcalloc(1, sizeof(*cctx)); 1026 cctx->rid = rid; 1027 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1028 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1029 1030 /* reply is deferred, sent by mux_session_confirm */ 1031 return 0; 1032 } 1033 1034 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1035 static void 1036 mux_stdio_confirm(int id, int success, void *arg) 1037 { 1038 struct mux_stdio_confirm_ctx *cctx = arg; 1039 Channel *c, *cc; 1040 Buffer reply; 1041 1042 if (cctx == NULL) 1043 fatal("%s: cctx == NULL", __func__); 1044 if ((c = channel_by_id(id)) == NULL) 1045 fatal("%s: no channel for id %d", __func__, id); 1046 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1047 fatal("%s: channel %d lacks control channel %d", __func__, 1048 id, c->ctl_chan); 1049 1050 if (!success) { 1051 debug3("%s: sending failure reply", __func__); 1052 /* prepare reply */ 1053 buffer_init(&reply); 1054 buffer_put_int(&reply, MUX_S_FAILURE); 1055 buffer_put_int(&reply, cctx->rid); 1056 buffer_put_cstring(&reply, "Session open refused by peer"); 1057 goto done; 1058 } 1059 1060 debug3("%s: sending success reply", __func__); 1061 /* prepare reply */ 1062 buffer_init(&reply); 1063 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1064 buffer_put_int(&reply, cctx->rid); 1065 buffer_put_int(&reply, c->self); 1066 1067 done: 1068 /* Send reply */ 1069 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1070 buffer_free(&reply); 1071 1072 if (cc->mux_pause <= 0) 1073 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1074 cc->mux_pause = 0; /* start processing messages again */ 1075 c->open_confirm_ctx = NULL; 1076 free(cctx); 1077 } 1078 1079 static int 1080 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1081 { 1082 debug("%s: channel %d: stop listening", __func__, c->self); 1083 1084 if (options.control_master == SSHCTL_MASTER_ASK || 1085 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1086 if (!ask_permission("Disable further multiplexing on shared " 1087 "connection to %s? ", host)) { 1088 debug2("%s: stop listen refused by user", __func__); 1089 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1090 buffer_put_int(r, rid); 1091 buffer_put_cstring(r, "Permission denied"); 1092 return 0; 1093 } 1094 } 1095 1096 if (mux_listener_channel != NULL) { 1097 channel_free(mux_listener_channel); 1098 client_stop_mux(); 1099 free(options.control_path); 1100 options.control_path = NULL; 1101 mux_listener_channel = NULL; 1102 muxserver_sock = -1; 1103 } 1104 1105 /* prepare reply */ 1106 buffer_put_int(r, MUX_S_OK); 1107 buffer_put_int(r, rid); 1108 1109 return 0; 1110 } 1111 1112 /* Channel callbacks fired on read/write from mux slave fd */ 1113 static int 1114 mux_master_read_cb(Channel *c) 1115 { 1116 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1117 Buffer in, out; 1118 const u_char *ptr; 1119 u_int type, rid, have, i; 1120 int ret = -1; 1121 1122 /* Setup ctx and */ 1123 if (c->mux_ctx == NULL) { 1124 state = xcalloc(1, sizeof(*state)); 1125 c->mux_ctx = state; 1126 channel_register_cleanup(c->self, 1127 mux_master_control_cleanup_cb, 0); 1128 1129 /* Send hello */ 1130 buffer_init(&out); 1131 buffer_put_int(&out, MUX_MSG_HELLO); 1132 buffer_put_int(&out, SSHMUX_VER); 1133 /* no extensions */ 1134 buffer_put_string(&c->output, buffer_ptr(&out), 1135 buffer_len(&out)); 1136 buffer_free(&out); 1137 debug3("%s: channel %d: hello sent", __func__, c->self); 1138 return 0; 1139 } 1140 1141 buffer_init(&in); 1142 buffer_init(&out); 1143 1144 /* Channel code ensures that we receive whole packets */ 1145 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1146 malf: 1147 error("%s: malformed message", __func__); 1148 goto out; 1149 } 1150 buffer_append(&in, ptr, have); 1151 1152 if (buffer_get_int_ret(&type, &in) != 0) 1153 goto malf; 1154 debug3("%s: channel %d packet type 0x%08x len %u", 1155 __func__, c->self, type, buffer_len(&in)); 1156 1157 if (type == MUX_MSG_HELLO) 1158 rid = 0; 1159 else { 1160 if (!state->hello_rcvd) { 1161 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1162 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1163 goto out; 1164 } 1165 if (buffer_get_int_ret(&rid, &in) != 0) 1166 goto malf; 1167 } 1168 1169 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1170 if (type == mux_master_handlers[i].type) { 1171 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1172 break; 1173 } 1174 } 1175 if (mux_master_handlers[i].handler == NULL) { 1176 error("%s: unsupported mux message 0x%08x", __func__, type); 1177 buffer_put_int(&out, MUX_S_FAILURE); 1178 buffer_put_int(&out, rid); 1179 buffer_put_cstring(&out, "unsupported request"); 1180 ret = 0; 1181 } 1182 /* Enqueue reply packet */ 1183 if (buffer_len(&out) != 0) { 1184 buffer_put_string(&c->output, buffer_ptr(&out), 1185 buffer_len(&out)); 1186 } 1187 out: 1188 buffer_free(&in); 1189 buffer_free(&out); 1190 return ret; 1191 } 1192 1193 void 1194 mux_exit_message(Channel *c, int exitval) 1195 { 1196 Buffer m; 1197 Channel *mux_chan; 1198 1199 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1200 exitval); 1201 1202 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1203 fatal("%s: channel %d missing mux channel %d", 1204 __func__, c->self, c->ctl_chan); 1205 1206 /* Append exit message packet to control socket output queue */ 1207 buffer_init(&m); 1208 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1209 buffer_put_int(&m, c->self); 1210 buffer_put_int(&m, exitval); 1211 1212 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1213 buffer_free(&m); 1214 } 1215 1216 void 1217 mux_tty_alloc_failed(Channel *c) 1218 { 1219 Buffer m; 1220 Channel *mux_chan; 1221 1222 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1223 1224 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1225 fatal("%s: channel %d missing mux channel %d", 1226 __func__, c->self, c->ctl_chan); 1227 1228 /* Append exit message packet to control socket output queue */ 1229 buffer_init(&m); 1230 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1231 buffer_put_int(&m, c->self); 1232 1233 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1234 buffer_free(&m); 1235 } 1236 1237 /* Prepare a mux master to listen on a Unix domain socket. */ 1238 void 1239 muxserver_listen(void) 1240 { 1241 mode_t old_umask; 1242 char *orig_control_path = options.control_path; 1243 char rbuf[16+1]; 1244 u_int i, r; 1245 int oerrno; 1246 1247 if (options.control_path == NULL || 1248 options.control_master == SSHCTL_MASTER_NO) 1249 return; 1250 1251 debug("setting up multiplex master socket"); 1252 1253 /* 1254 * Use a temporary path before listen so we can pseudo-atomically 1255 * establish the listening socket in its final location to avoid 1256 * other processes racing in between bind() and listen() and hitting 1257 * an unready socket. 1258 */ 1259 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1260 r = arc4random_uniform(26+26+10); 1261 rbuf[i] = (r < 26) ? 'a' + r : 1262 (r < 26*2) ? 'A' + r - 26 : 1263 '0' + r - 26 - 26; 1264 } 1265 rbuf[sizeof(rbuf) - 1] = '\0'; 1266 options.control_path = NULL; 1267 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1268 debug3("%s: temporary control path %s", __func__, options.control_path); 1269 1270 old_umask = umask(0177); 1271 muxserver_sock = unix_listener(options.control_path, 64, 0); 1272 oerrno = errno; 1273 umask(old_umask); 1274 if (muxserver_sock < 0) { 1275 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1276 error("ControlSocket %s already exists, " 1277 "disabling multiplexing", options.control_path); 1278 disable_mux_master: 1279 if (muxserver_sock != -1) { 1280 close(muxserver_sock); 1281 muxserver_sock = -1; 1282 } 1283 free(orig_control_path); 1284 free(options.control_path); 1285 options.control_path = NULL; 1286 options.control_master = SSHCTL_MASTER_NO; 1287 return; 1288 } else { 1289 /* unix_listener() logs the error */ 1290 cleanup_exit(255); 1291 } 1292 } 1293 1294 /* Now atomically "move" the mux socket into position */ 1295 if (link(options.control_path, orig_control_path) != 0) { 1296 if (errno != EEXIST) { 1297 fatal("%s: link mux listener %s => %s: %s", __func__, 1298 options.control_path, orig_control_path, 1299 strerror(errno)); 1300 } 1301 error("ControlSocket %s already exists, disabling multiplexing", 1302 orig_control_path); 1303 unlink(options.control_path); 1304 goto disable_mux_master; 1305 } 1306 unlink(options.control_path); 1307 free(options.control_path); 1308 options.control_path = orig_control_path; 1309 1310 set_nonblock(muxserver_sock); 1311 1312 mux_listener_channel = channel_new("mux listener", 1313 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1314 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1315 0, options.control_path, 1); 1316 mux_listener_channel->mux_rcb = mux_master_read_cb; 1317 debug3("%s: mux listener channel %d fd %d", __func__, 1318 mux_listener_channel->self, mux_listener_channel->sock); 1319 } 1320 1321 /* Callback on open confirmation in mux master for a mux client session. */ 1322 static void 1323 mux_session_confirm(int id, int success, void *arg) 1324 { 1325 struct mux_session_confirm_ctx *cctx = arg; 1326 const char *display; 1327 Channel *c, *cc; 1328 int i; 1329 Buffer reply; 1330 1331 if (cctx == NULL) 1332 fatal("%s: cctx == NULL", __func__); 1333 if ((c = channel_by_id(id)) == NULL) 1334 fatal("%s: no channel for id %d", __func__, id); 1335 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1336 fatal("%s: channel %d lacks control channel %d", __func__, 1337 id, c->ctl_chan); 1338 1339 if (!success) { 1340 debug3("%s: sending failure reply", __func__); 1341 /* prepare reply */ 1342 buffer_init(&reply); 1343 buffer_put_int(&reply, MUX_S_FAILURE); 1344 buffer_put_int(&reply, cctx->rid); 1345 buffer_put_cstring(&reply, "Session open refused by peer"); 1346 goto done; 1347 } 1348 1349 display = getenv("DISPLAY"); 1350 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1351 char *proto, *data; 1352 1353 /* Get reasonable local authentication information. */ 1354 client_x11_get_proto(display, options.xauth_location, 1355 options.forward_x11_trusted, options.forward_x11_timeout, 1356 &proto, &data); 1357 /* Request forwarding with authentication spoofing. */ 1358 debug("Requesting X11 forwarding with authentication " 1359 "spoofing."); 1360 x11_request_forwarding_with_spoofing(id, display, proto, 1361 data, 1); 1362 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1363 /* XXX exit_on_forward_failure */ 1364 } 1365 1366 if (cctx->want_agent_fwd && options.forward_agent) { 1367 debug("Requesting authentication agent forwarding."); 1368 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1369 packet_send(); 1370 } 1371 1372 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1373 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1374 1375 debug3("%s: sending success reply", __func__); 1376 /* prepare reply */ 1377 buffer_init(&reply); 1378 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1379 buffer_put_int(&reply, cctx->rid); 1380 buffer_put_int(&reply, c->self); 1381 1382 done: 1383 /* Send reply */ 1384 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1385 buffer_free(&reply); 1386 1387 if (cc->mux_pause <= 0) 1388 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1389 cc->mux_pause = 0; /* start processing messages again */ 1390 c->open_confirm_ctx = NULL; 1391 buffer_free(&cctx->cmd); 1392 free(cctx->term); 1393 if (cctx->env != NULL) { 1394 for (i = 0; cctx->env[i] != NULL; i++) 1395 free(cctx->env[i]); 1396 free(cctx->env); 1397 } 1398 free(cctx); 1399 } 1400 1401 /* ** Multiplexing client support */ 1402 1403 /* Exit signal handler */ 1404 static void 1405 control_client_sighandler(int signo) 1406 { 1407 muxclient_terminate = signo; 1408 } 1409 1410 /* 1411 * Relay signal handler - used to pass some signals from mux client to 1412 * mux master. 1413 */ 1414 static void 1415 control_client_sigrelay(int signo) 1416 { 1417 int save_errno = errno; 1418 1419 if (muxserver_pid > 1) 1420 kill(muxserver_pid, signo); 1421 1422 errno = save_errno; 1423 } 1424 1425 static int 1426 mux_client_read(int fd, Buffer *b, u_int need) 1427 { 1428 u_int have; 1429 ssize_t len; 1430 u_char *p; 1431 struct pollfd pfd; 1432 1433 pfd.fd = fd; 1434 pfd.events = POLLIN; 1435 p = buffer_append_space(b, need); 1436 for (have = 0; have < need; ) { 1437 if (muxclient_terminate) { 1438 errno = EINTR; 1439 return -1; 1440 } 1441 len = read(fd, p + have, need - have); 1442 if (len < 0) { 1443 switch (errno) { 1444 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1445 case EWOULDBLOCK: 1446 #endif 1447 case EAGAIN: 1448 (void)poll(&pfd, 1, -1); 1449 /* FALLTHROUGH */ 1450 case EINTR: 1451 continue; 1452 default: 1453 return -1; 1454 } 1455 } 1456 if (len == 0) { 1457 errno = EPIPE; 1458 return -1; 1459 } 1460 have += (u_int)len; 1461 } 1462 return 0; 1463 } 1464 1465 static int 1466 mux_client_write_packet(int fd, Buffer *m) 1467 { 1468 Buffer queue; 1469 u_int have, need; 1470 int oerrno, len; 1471 u_char *ptr; 1472 struct pollfd pfd; 1473 1474 pfd.fd = fd; 1475 pfd.events = POLLOUT; 1476 buffer_init(&queue); 1477 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1478 1479 need = buffer_len(&queue); 1480 ptr = buffer_ptr(&queue); 1481 1482 for (have = 0; have < need; ) { 1483 if (muxclient_terminate) { 1484 buffer_free(&queue); 1485 errno = EINTR; 1486 return -1; 1487 } 1488 len = write(fd, ptr + have, need - have); 1489 if (len < 0) { 1490 switch (errno) { 1491 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1492 case EWOULDBLOCK: 1493 #endif 1494 case EAGAIN: 1495 (void)poll(&pfd, 1, -1); 1496 /* FALLTHROUGH */ 1497 case EINTR: 1498 continue; 1499 default: 1500 oerrno = errno; 1501 buffer_free(&queue); 1502 errno = oerrno; 1503 return -1; 1504 } 1505 } 1506 if (len == 0) { 1507 buffer_free(&queue); 1508 errno = EPIPE; 1509 return -1; 1510 } 1511 have += (u_int)len; 1512 } 1513 buffer_free(&queue); 1514 return 0; 1515 } 1516 1517 static int 1518 mux_client_read_packet(int fd, Buffer *m) 1519 { 1520 Buffer queue; 1521 u_int need, have; 1522 const u_char *ptr; 1523 int oerrno; 1524 1525 buffer_init(&queue); 1526 if (mux_client_read(fd, &queue, 4) != 0) { 1527 if ((oerrno = errno) == EPIPE) 1528 debug3("%s: read header failed: %s", __func__, 1529 strerror(errno)); 1530 buffer_free(&queue); 1531 errno = oerrno; 1532 return -1; 1533 } 1534 need = get_u32(buffer_ptr(&queue)); 1535 if (mux_client_read(fd, &queue, need) != 0) { 1536 oerrno = errno; 1537 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1538 buffer_free(&queue); 1539 errno = oerrno; 1540 return -1; 1541 } 1542 ptr = buffer_get_string_ptr(&queue, &have); 1543 buffer_append(m, ptr, have); 1544 buffer_free(&queue); 1545 return 0; 1546 } 1547 1548 static int 1549 mux_client_hello_exchange(int fd) 1550 { 1551 Buffer m; 1552 u_int type, ver; 1553 1554 buffer_init(&m); 1555 buffer_put_int(&m, MUX_MSG_HELLO); 1556 buffer_put_int(&m, SSHMUX_VER); 1557 /* no extensions */ 1558 1559 if (mux_client_write_packet(fd, &m) != 0) 1560 fatal("%s: write packet: %s", __func__, strerror(errno)); 1561 1562 buffer_clear(&m); 1563 1564 /* Read their HELLO */ 1565 if (mux_client_read_packet(fd, &m) != 0) { 1566 buffer_free(&m); 1567 return -1; 1568 } 1569 1570 type = buffer_get_int(&m); 1571 if (type != MUX_MSG_HELLO) 1572 fatal("%s: expected HELLO (%u) received %u", 1573 __func__, MUX_MSG_HELLO, type); 1574 ver = buffer_get_int(&m); 1575 if (ver != SSHMUX_VER) 1576 fatal("Unsupported multiplexing protocol version %d " 1577 "(expected %d)", ver, SSHMUX_VER); 1578 debug2("%s: master version %u", __func__, ver); 1579 /* No extensions are presently defined */ 1580 while (buffer_len(&m) > 0) { 1581 char *name = buffer_get_string(&m, NULL); 1582 char *value = buffer_get_string(&m, NULL); 1583 1584 debug2("Unrecognised master extension \"%s\"", name); 1585 free(name); 1586 free(value); 1587 } 1588 buffer_free(&m); 1589 return 0; 1590 } 1591 1592 static u_int 1593 mux_client_request_alive(int fd) 1594 { 1595 Buffer m; 1596 char *e; 1597 u_int pid, type, rid; 1598 1599 debug3("%s: entering", __func__); 1600 1601 buffer_init(&m); 1602 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1603 buffer_put_int(&m, muxclient_request_id); 1604 1605 if (mux_client_write_packet(fd, &m) != 0) 1606 fatal("%s: write packet: %s", __func__, strerror(errno)); 1607 1608 buffer_clear(&m); 1609 1610 /* Read their reply */ 1611 if (mux_client_read_packet(fd, &m) != 0) { 1612 buffer_free(&m); 1613 return 0; 1614 } 1615 1616 type = buffer_get_int(&m); 1617 if (type != MUX_S_ALIVE) { 1618 e = buffer_get_string(&m, NULL); 1619 fatal("%s: master returned error: %s", __func__, e); 1620 } 1621 1622 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1623 fatal("%s: out of sequence reply: my id %u theirs %u", 1624 __func__, muxclient_request_id, rid); 1625 pid = buffer_get_int(&m); 1626 buffer_free(&m); 1627 1628 debug3("%s: done pid = %u", __func__, pid); 1629 1630 muxclient_request_id++; 1631 1632 return pid; 1633 } 1634 1635 static void 1636 mux_client_request_terminate(int fd) 1637 { 1638 Buffer m; 1639 char *e; 1640 u_int type, rid; 1641 1642 debug3("%s: entering", __func__); 1643 1644 buffer_init(&m); 1645 buffer_put_int(&m, MUX_C_TERMINATE); 1646 buffer_put_int(&m, muxclient_request_id); 1647 1648 if (mux_client_write_packet(fd, &m) != 0) 1649 fatal("%s: write packet: %s", __func__, strerror(errno)); 1650 1651 buffer_clear(&m); 1652 1653 /* Read their reply */ 1654 if (mux_client_read_packet(fd, &m) != 0) { 1655 /* Remote end exited already */ 1656 if (errno == EPIPE) { 1657 buffer_free(&m); 1658 return; 1659 } 1660 fatal("%s: read from master failed: %s", 1661 __func__, strerror(errno)); 1662 } 1663 1664 type = buffer_get_int(&m); 1665 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1666 fatal("%s: out of sequence reply: my id %u theirs %u", 1667 __func__, muxclient_request_id, rid); 1668 switch (type) { 1669 case MUX_S_OK: 1670 break; 1671 case MUX_S_PERMISSION_DENIED: 1672 e = buffer_get_string(&m, NULL); 1673 fatal("Master refused termination request: %s", e); 1674 case MUX_S_FAILURE: 1675 e = buffer_get_string(&m, NULL); 1676 fatal("%s: termination request failed: %s", __func__, e); 1677 default: 1678 fatal("%s: unexpected response from master 0x%08x", 1679 __func__, type); 1680 } 1681 buffer_free(&m); 1682 muxclient_request_id++; 1683 } 1684 1685 static int 1686 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1687 { 1688 Buffer m; 1689 char *e, *fwd_desc; 1690 u_int type, rid; 1691 1692 fwd_desc = format_forward(ftype, fwd); 1693 debug("Requesting %s %s", 1694 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1695 free(fwd_desc); 1696 1697 buffer_init(&m); 1698 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1699 buffer_put_int(&m, muxclient_request_id); 1700 buffer_put_int(&m, ftype); 1701 if (fwd->listen_path != NULL) { 1702 buffer_put_cstring(&m, fwd->listen_path); 1703 } else { 1704 buffer_put_cstring(&m, 1705 fwd->listen_host == NULL ? "" : 1706 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1707 } 1708 buffer_put_int(&m, fwd->listen_port); 1709 if (fwd->connect_path != NULL) { 1710 buffer_put_cstring(&m, fwd->connect_path); 1711 } else { 1712 buffer_put_cstring(&m, 1713 fwd->connect_host == NULL ? "" : fwd->connect_host); 1714 } 1715 buffer_put_int(&m, fwd->connect_port); 1716 1717 if (mux_client_write_packet(fd, &m) != 0) 1718 fatal("%s: write packet: %s", __func__, strerror(errno)); 1719 1720 buffer_clear(&m); 1721 1722 /* Read their reply */ 1723 if (mux_client_read_packet(fd, &m) != 0) { 1724 buffer_free(&m); 1725 return -1; 1726 } 1727 1728 type = buffer_get_int(&m); 1729 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1730 fatal("%s: out of sequence reply: my id %u theirs %u", 1731 __func__, muxclient_request_id, rid); 1732 switch (type) { 1733 case MUX_S_OK: 1734 break; 1735 case MUX_S_REMOTE_PORT: 1736 if (cancel_flag) 1737 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1738 fwd->allocated_port = buffer_get_int(&m); 1739 verbose("Allocated port %u for remote forward to %s:%d", 1740 fwd->allocated_port, 1741 fwd->connect_host ? fwd->connect_host : "", 1742 fwd->connect_port); 1743 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1744 fprintf(stdout, "%u\n", fwd->allocated_port); 1745 break; 1746 case MUX_S_PERMISSION_DENIED: 1747 e = buffer_get_string(&m, NULL); 1748 buffer_free(&m); 1749 error("Master refused forwarding request: %s", e); 1750 return -1; 1751 case MUX_S_FAILURE: 1752 e = buffer_get_string(&m, NULL); 1753 buffer_free(&m); 1754 error("%s: forwarding request failed: %s", __func__, e); 1755 return -1; 1756 default: 1757 fatal("%s: unexpected response from master 0x%08x", 1758 __func__, type); 1759 } 1760 buffer_free(&m); 1761 1762 muxclient_request_id++; 1763 return 0; 1764 } 1765 1766 static int 1767 mux_client_forwards(int fd, int cancel_flag) 1768 { 1769 int i, ret = 0; 1770 1771 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1772 cancel_flag ? "cancel" : "request", 1773 options.num_local_forwards, options.num_remote_forwards); 1774 1775 /* XXX ExitOnForwardingFailure */ 1776 for (i = 0; i < options.num_local_forwards; i++) { 1777 if (mux_client_forward(fd, cancel_flag, 1778 options.local_forwards[i].connect_port == 0 ? 1779 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1780 options.local_forwards + i) != 0) 1781 ret = -1; 1782 } 1783 for (i = 0; i < options.num_remote_forwards; i++) { 1784 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1785 options.remote_forwards + i) != 0) 1786 ret = -1; 1787 } 1788 return ret; 1789 } 1790 1791 static int 1792 mux_client_request_session(int fd) 1793 { 1794 Buffer m; 1795 char *e, *term; 1796 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1797 extern char **environ; 1798 int devnull, rawmode; 1799 1800 debug3("%s: entering", __func__); 1801 1802 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1803 error("%s: master alive request failed", __func__); 1804 return -1; 1805 } 1806 1807 signal(SIGPIPE, SIG_IGN); 1808 1809 if (stdin_null_flag) { 1810 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1811 fatal("open(/dev/null): %s", strerror(errno)); 1812 if (dup2(devnull, STDIN_FILENO) == -1) 1813 fatal("dup2: %s", strerror(errno)); 1814 if (devnull > STDERR_FILENO) 1815 close(devnull); 1816 } 1817 1818 term = getenv("TERM"); 1819 1820 buffer_init(&m); 1821 buffer_put_int(&m, MUX_C_NEW_SESSION); 1822 buffer_put_int(&m, muxclient_request_id); 1823 buffer_put_cstring(&m, ""); /* reserved */ 1824 buffer_put_int(&m, tty_flag); 1825 buffer_put_int(&m, options.forward_x11); 1826 buffer_put_int(&m, options.forward_agent); 1827 buffer_put_int(&m, subsystem_flag); 1828 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1829 0xffffffff : (u_int)options.escape_char); 1830 buffer_put_cstring(&m, term == NULL ? "" : term); 1831 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1832 1833 if (options.num_send_env > 0 && environ != NULL) { 1834 /* Pass environment */ 1835 for (i = 0; environ[i] != NULL; i++) { 1836 if (env_permitted(environ[i])) { 1837 buffer_put_cstring(&m, environ[i]); 1838 } 1839 } 1840 } 1841 1842 if (mux_client_write_packet(fd, &m) != 0) 1843 fatal("%s: write packet: %s", __func__, strerror(errno)); 1844 1845 /* Send the stdio file descriptors */ 1846 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1847 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1848 mm_send_fd(fd, STDERR_FILENO) == -1) 1849 fatal("%s: send fds failed", __func__); 1850 1851 debug3("%s: session request sent", __func__); 1852 1853 /* Read their reply */ 1854 buffer_clear(&m); 1855 if (mux_client_read_packet(fd, &m) != 0) { 1856 error("%s: read from master failed: %s", 1857 __func__, strerror(errno)); 1858 buffer_free(&m); 1859 return -1; 1860 } 1861 1862 type = buffer_get_int(&m); 1863 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1864 fatal("%s: out of sequence reply: my id %u theirs %u", 1865 __func__, muxclient_request_id, rid); 1866 switch (type) { 1867 case MUX_S_SESSION_OPENED: 1868 sid = buffer_get_int(&m); 1869 debug("%s: master session id: %u", __func__, sid); 1870 break; 1871 case MUX_S_PERMISSION_DENIED: 1872 e = buffer_get_string(&m, NULL); 1873 buffer_free(&m); 1874 error("Master refused session request: %s", e); 1875 return -1; 1876 case MUX_S_FAILURE: 1877 e = buffer_get_string(&m, NULL); 1878 buffer_free(&m); 1879 error("%s: session request failed: %s", __func__, e); 1880 return -1; 1881 default: 1882 buffer_free(&m); 1883 error("%s: unexpected response from master 0x%08x", 1884 __func__, type); 1885 return -1; 1886 } 1887 muxclient_request_id++; 1888 1889 signal(SIGHUP, control_client_sighandler); 1890 signal(SIGINT, control_client_sighandler); 1891 signal(SIGTERM, control_client_sighandler); 1892 signal(SIGWINCH, control_client_sigrelay); 1893 1894 rawmode = tty_flag; 1895 if (tty_flag) 1896 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1897 1898 /* 1899 * Stick around until the controlee closes the client_fd. 1900 * Before it does, it is expected to write an exit message. 1901 * This process must read the value and wait for the closure of 1902 * the client_fd; if this one closes early, the multiplex master will 1903 * terminate early too (possibly losing data). 1904 */ 1905 for (exitval = 255, exitval_seen = 0;;) { 1906 buffer_clear(&m); 1907 if (mux_client_read_packet(fd, &m) != 0) 1908 break; 1909 type = buffer_get_int(&m); 1910 switch (type) { 1911 case MUX_S_TTY_ALLOC_FAIL: 1912 if ((esid = buffer_get_int(&m)) != sid) 1913 fatal("%s: tty alloc fail on unknown session: " 1914 "my id %u theirs %u", 1915 __func__, sid, esid); 1916 leave_raw_mode(options.request_tty == 1917 REQUEST_TTY_FORCE); 1918 rawmode = 0; 1919 continue; 1920 case MUX_S_EXIT_MESSAGE: 1921 if ((esid = buffer_get_int(&m)) != sid) 1922 fatal("%s: exit on unknown session: " 1923 "my id %u theirs %u", 1924 __func__, sid, esid); 1925 if (exitval_seen) 1926 fatal("%s: exitval sent twice", __func__); 1927 exitval = buffer_get_int(&m); 1928 exitval_seen = 1; 1929 continue; 1930 default: 1931 e = buffer_get_string(&m, NULL); 1932 fatal("%s: master returned error: %s", __func__, e); 1933 } 1934 } 1935 1936 close(fd); 1937 if (rawmode) 1938 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1939 1940 if (muxclient_terminate) { 1941 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1942 exitval = 255; 1943 } else if (!exitval_seen) { 1944 debug2("Control master terminated unexpectedly"); 1945 exitval = 255; 1946 } else 1947 debug2("Received exit status from master %d", exitval); 1948 1949 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1950 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1951 1952 exit(exitval); 1953 } 1954 1955 static int 1956 mux_client_request_stdio_fwd(int fd) 1957 { 1958 Buffer m; 1959 char *e; 1960 u_int type, rid, sid; 1961 int devnull; 1962 1963 debug3("%s: entering", __func__); 1964 1965 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1966 error("%s: master alive request failed", __func__); 1967 return -1; 1968 } 1969 1970 signal(SIGPIPE, SIG_IGN); 1971 1972 if (stdin_null_flag) { 1973 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1974 fatal("open(/dev/null): %s", strerror(errno)); 1975 if (dup2(devnull, STDIN_FILENO) == -1) 1976 fatal("dup2: %s", strerror(errno)); 1977 if (devnull > STDERR_FILENO) 1978 close(devnull); 1979 } 1980 1981 buffer_init(&m); 1982 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1983 buffer_put_int(&m, muxclient_request_id); 1984 buffer_put_cstring(&m, ""); /* reserved */ 1985 buffer_put_cstring(&m, stdio_forward_host); 1986 buffer_put_int(&m, stdio_forward_port); 1987 1988 if (mux_client_write_packet(fd, &m) != 0) 1989 fatal("%s: write packet: %s", __func__, strerror(errno)); 1990 1991 /* Send the stdio file descriptors */ 1992 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1993 mm_send_fd(fd, STDOUT_FILENO) == -1) 1994 fatal("%s: send fds failed", __func__); 1995 1996 debug3("%s: stdio forward request sent", __func__); 1997 1998 /* Read their reply */ 1999 buffer_clear(&m); 2000 2001 if (mux_client_read_packet(fd, &m) != 0) { 2002 error("%s: read from master failed: %s", 2003 __func__, strerror(errno)); 2004 buffer_free(&m); 2005 return -1; 2006 } 2007 2008 type = buffer_get_int(&m); 2009 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2010 fatal("%s: out of sequence reply: my id %u theirs %u", 2011 __func__, muxclient_request_id, rid); 2012 switch (type) { 2013 case MUX_S_SESSION_OPENED: 2014 sid = buffer_get_int(&m); 2015 debug("%s: master session id: %u", __func__, sid); 2016 break; 2017 case MUX_S_PERMISSION_DENIED: 2018 e = buffer_get_string(&m, NULL); 2019 buffer_free(&m); 2020 fatal("Master refused stdio forwarding request: %s", e); 2021 case MUX_S_FAILURE: 2022 e = buffer_get_string(&m, NULL); 2023 buffer_free(&m); 2024 fatal("Stdio forwarding request failed: %s", e); 2025 default: 2026 buffer_free(&m); 2027 error("%s: unexpected response from master 0x%08x", 2028 __func__, type); 2029 return -1; 2030 } 2031 muxclient_request_id++; 2032 2033 signal(SIGHUP, control_client_sighandler); 2034 signal(SIGINT, control_client_sighandler); 2035 signal(SIGTERM, control_client_sighandler); 2036 signal(SIGWINCH, control_client_sigrelay); 2037 2038 /* 2039 * Stick around until the controlee closes the client_fd. 2040 */ 2041 buffer_clear(&m); 2042 if (mux_client_read_packet(fd, &m) != 0) { 2043 if (errno == EPIPE || 2044 (errno == EINTR && muxclient_terminate != 0)) 2045 return 0; 2046 fatal("%s: mux_client_read_packet: %s", 2047 __func__, strerror(errno)); 2048 } 2049 fatal("%s: master returned unexpected message %u", __func__, type); 2050 } 2051 2052 static void 2053 mux_client_request_stop_listening(int fd) 2054 { 2055 Buffer m; 2056 char *e; 2057 u_int type, rid; 2058 2059 debug3("%s: entering", __func__); 2060 2061 buffer_init(&m); 2062 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2063 buffer_put_int(&m, muxclient_request_id); 2064 2065 if (mux_client_write_packet(fd, &m) != 0) 2066 fatal("%s: write packet: %s", __func__, strerror(errno)); 2067 2068 buffer_clear(&m); 2069 2070 /* Read their reply */ 2071 if (mux_client_read_packet(fd, &m) != 0) 2072 fatal("%s: read from master failed: %s", 2073 __func__, strerror(errno)); 2074 2075 type = buffer_get_int(&m); 2076 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2077 fatal("%s: out of sequence reply: my id %u theirs %u", 2078 __func__, muxclient_request_id, rid); 2079 switch (type) { 2080 case MUX_S_OK: 2081 break; 2082 case MUX_S_PERMISSION_DENIED: 2083 e = buffer_get_string(&m, NULL); 2084 fatal("Master refused stop listening request: %s", e); 2085 case MUX_S_FAILURE: 2086 e = buffer_get_string(&m, NULL); 2087 fatal("%s: stop listening request failed: %s", __func__, e); 2088 default: 2089 fatal("%s: unexpected response from master 0x%08x", 2090 __func__, type); 2091 } 2092 buffer_free(&m); 2093 muxclient_request_id++; 2094 } 2095 2096 /* Multiplex client main loop. */ 2097 void 2098 muxclient(const char *path) 2099 { 2100 struct sockaddr_un addr; 2101 socklen_t sun_len; 2102 int sock; 2103 u_int pid; 2104 2105 if (muxclient_command == 0) { 2106 if (stdio_forward_host != NULL) 2107 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2108 else 2109 muxclient_command = SSHMUX_COMMAND_OPEN; 2110 } 2111 2112 switch (options.control_master) { 2113 case SSHCTL_MASTER_AUTO: 2114 case SSHCTL_MASTER_AUTO_ASK: 2115 debug("auto-mux: Trying existing master"); 2116 /* FALLTHROUGH */ 2117 case SSHCTL_MASTER_NO: 2118 break; 2119 default: 2120 return; 2121 } 2122 2123 memset(&addr, '\0', sizeof(addr)); 2124 addr.sun_family = AF_UNIX; 2125 sun_len = offsetof(struct sockaddr_un, sun_path) + 2126 strlen(path) + 1; 2127 2128 if (strlcpy(addr.sun_path, path, 2129 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2130 fatal("ControlPath too long"); 2131 2132 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2133 fatal("%s socket(): %s", __func__, strerror(errno)); 2134 2135 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2136 switch (muxclient_command) { 2137 case SSHMUX_COMMAND_OPEN: 2138 case SSHMUX_COMMAND_STDIO_FWD: 2139 break; 2140 default: 2141 fatal("Control socket connect(%.100s): %s", path, 2142 strerror(errno)); 2143 } 2144 if (errno == ECONNREFUSED && 2145 options.control_master != SSHCTL_MASTER_NO) { 2146 debug("Stale control socket %.100s, unlinking", path); 2147 unlink(path); 2148 } else if (errno == ENOENT) { 2149 debug("Control socket \"%.100s\" does not exist", path); 2150 } else { 2151 error("Control socket connect(%.100s): %s", path, 2152 strerror(errno)); 2153 } 2154 close(sock); 2155 return; 2156 } 2157 set_nonblock(sock); 2158 2159 if (mux_client_hello_exchange(sock) != 0) { 2160 error("%s: master hello exchange failed", __func__); 2161 close(sock); 2162 return; 2163 } 2164 2165 switch (muxclient_command) { 2166 case SSHMUX_COMMAND_ALIVE_CHECK: 2167 if ((pid = mux_client_request_alive(sock)) == 0) 2168 fatal("%s: master alive check failed", __func__); 2169 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2170 exit(0); 2171 case SSHMUX_COMMAND_TERMINATE: 2172 mux_client_request_terminate(sock); 2173 fprintf(stderr, "Exit request sent.\r\n"); 2174 exit(0); 2175 case SSHMUX_COMMAND_FORWARD: 2176 if (mux_client_forwards(sock, 0) != 0) 2177 fatal("%s: master forward request failed", __func__); 2178 exit(0); 2179 case SSHMUX_COMMAND_OPEN: 2180 if (mux_client_forwards(sock, 0) != 0) { 2181 error("%s: master forward request failed", __func__); 2182 return; 2183 } 2184 mux_client_request_session(sock); 2185 return; 2186 case SSHMUX_COMMAND_STDIO_FWD: 2187 mux_client_request_stdio_fwd(sock); 2188 exit(0); 2189 case SSHMUX_COMMAND_STOP: 2190 mux_client_request_stop_listening(sock); 2191 fprintf(stderr, "Stop listening request sent.\r\n"); 2192 exit(0); 2193 case SSHMUX_COMMAND_CANCEL_FWD: 2194 if (mux_client_forwards(sock, 1) != 0) 2195 error("%s: master cancel forward request failed", 2196 __func__); 2197 exit(0); 2198 default: 2199 fatal("unrecognised muxclient_command %d", muxclient_command); 2200 } 2201 } 2202