1 /* $OpenBSD: mux.c,v 1.44 2013/07/12 00:19:58 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 <sys/types.h> 34 #include <sys/param.h> 35 #include <sys/queue.h> 36 #include <sys/stat.h> 37 #include <sys/socket.h> 38 #include <sys/un.h> 39 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <poll.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 #include <util.h> 51 #include <paths.h> 52 53 #include "atomicio.h" 54 #include "xmalloc.h" 55 #include "log.h" 56 #include "ssh.h" 57 #include "ssh2.h" 58 #include "pathnames.h" 59 #include "misc.h" 60 #include "match.h" 61 #include "buffer.h" 62 #include "channels.h" 63 #include "msg.h" 64 #include "packet.h" 65 #include "monitor_fdpass.h" 66 #include "sshpty.h" 67 #include "key.h" 68 #include "readconf.h" 69 #include "clientloop.h" 70 71 /* from ssh.c */ 72 extern int tty_flag; 73 extern Options options; 74 extern int stdin_null_flag; 75 extern char *host; 76 extern int subsystem_flag; 77 extern Buffer command; 78 extern volatile sig_atomic_t quit_pending; 79 extern char *stdio_forward_host; 80 extern int stdio_forward_port; 81 82 /* Context for session open confirmation callback */ 83 struct mux_session_confirm_ctx { 84 u_int want_tty; 85 u_int want_subsys; 86 u_int want_x_fwd; 87 u_int want_agent_fwd; 88 Buffer cmd; 89 char *term; 90 struct termios tio; 91 char **env; 92 u_int rid; 93 }; 94 95 /* Context for global channel callback */ 96 struct mux_channel_confirm_ctx { 97 u_int cid; /* channel id */ 98 u_int rid; /* request id */ 99 int fid; /* forward id */ 100 }; 101 102 /* fd to control socket */ 103 int muxserver_sock = -1; 104 105 /* client request id */ 106 u_int muxclient_request_id = 0; 107 108 /* Multiplexing control command */ 109 u_int muxclient_command = 0; 110 111 /* Set when signalled. */ 112 static volatile sig_atomic_t muxclient_terminate = 0; 113 114 /* PID of multiplex server */ 115 static u_int muxserver_pid = 0; 116 117 static Channel *mux_listener_channel = NULL; 118 119 struct mux_master_state { 120 int hello_rcvd; 121 }; 122 123 /* mux protocol messages */ 124 #define MUX_MSG_HELLO 0x00000001 125 #define MUX_C_NEW_SESSION 0x10000002 126 #define MUX_C_ALIVE_CHECK 0x10000004 127 #define MUX_C_TERMINATE 0x10000005 128 #define MUX_C_OPEN_FWD 0x10000006 129 #define MUX_C_CLOSE_FWD 0x10000007 130 #define MUX_C_NEW_STDIO_FWD 0x10000008 131 #define MUX_C_STOP_LISTENING 0x10000009 132 #define MUX_S_OK 0x80000001 133 #define MUX_S_PERMISSION_DENIED 0x80000002 134 #define MUX_S_FAILURE 0x80000003 135 #define MUX_S_EXIT_MESSAGE 0x80000004 136 #define MUX_S_ALIVE 0x80000005 137 #define MUX_S_SESSION_OPENED 0x80000006 138 #define MUX_S_REMOTE_PORT 0x80000007 139 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 140 141 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 142 #define MUX_FWD_LOCAL 1 143 #define MUX_FWD_REMOTE 2 144 #define MUX_FWD_DYNAMIC 3 145 146 static void mux_session_confirm(int, int, void *); 147 148 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 149 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 150 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 151 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 152 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 153 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 154 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 155 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 156 157 static const struct { 158 u_int type; 159 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 160 } mux_master_handlers[] = { 161 { MUX_MSG_HELLO, process_mux_master_hello }, 162 { MUX_C_NEW_SESSION, process_mux_new_session }, 163 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 164 { MUX_C_TERMINATE, process_mux_terminate }, 165 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 166 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 167 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 168 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 169 { 0, NULL } 170 }; 171 172 /* Cleanup callback fired on closure of mux slave _session_ channel */ 173 /* ARGSUSED */ 174 static void 175 mux_master_session_cleanup_cb(int cid, void *unused) 176 { 177 Channel *cc, *c = channel_by_id(cid); 178 179 debug3("%s: entering for channel %d", __func__, cid); 180 if (c == NULL) 181 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 182 if (c->ctl_chan != -1) { 183 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 184 fatal("%s: channel %d missing control channel %d", 185 __func__, c->self, c->ctl_chan); 186 c->ctl_chan = -1; 187 cc->remote_id = -1; 188 chan_rcvd_oclose(cc); 189 } 190 channel_cancel_cleanup(c->self); 191 } 192 193 /* Cleanup callback fired on closure of mux slave _control_ channel */ 194 /* ARGSUSED */ 195 static void 196 mux_master_control_cleanup_cb(int cid, void *unused) 197 { 198 Channel *sc, *c = channel_by_id(cid); 199 200 debug3("%s: entering for channel %d", __func__, cid); 201 if (c == NULL) 202 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 203 if (c->remote_id != -1) { 204 if ((sc = channel_by_id(c->remote_id)) == NULL) 205 fatal("%s: channel %d missing session channel %d", 206 __func__, c->self, c->remote_id); 207 c->remote_id = -1; 208 sc->ctl_chan = -1; 209 if (sc->type != SSH_CHANNEL_OPEN && 210 sc->type != SSH_CHANNEL_OPENING) { 211 debug2("%s: channel %d: not open", __func__, sc->self); 212 chan_mark_dead(sc); 213 } else { 214 if (sc->istate == CHAN_INPUT_OPEN) 215 chan_read_failed(sc); 216 if (sc->ostate == CHAN_OUTPUT_OPEN) 217 chan_write_failed(sc); 218 } 219 } 220 channel_cancel_cleanup(c->self); 221 } 222 223 /* Check mux client environment variables before passing them to mux master. */ 224 static int 225 env_permitted(char *env) 226 { 227 int i, ret; 228 char name[1024], *cp; 229 230 if ((cp = strchr(env, '=')) == NULL || cp == env) 231 return 0; 232 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 233 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 234 error("env_permitted: name '%.100s...' too long", env); 235 return 0; 236 } 237 238 for (i = 0; i < options.num_send_env; i++) 239 if (match_pattern(name, options.send_env[i])) 240 return 1; 241 242 return 0; 243 } 244 245 /* Mux master protocol message handlers */ 246 247 static int 248 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 249 { 250 u_int ver; 251 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 252 253 if (state == NULL) 254 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 255 if (state->hello_rcvd) { 256 error("%s: HELLO received twice", __func__); 257 return -1; 258 } 259 if (buffer_get_int_ret(&ver, m) != 0) { 260 malf: 261 error("%s: malformed message", __func__); 262 return -1; 263 } 264 if (ver != SSHMUX_VER) { 265 error("Unsupported multiplexing protocol version %d " 266 "(expected %d)", ver, SSHMUX_VER); 267 return -1; 268 } 269 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 270 271 /* No extensions are presently defined */ 272 while (buffer_len(m) > 0) { 273 char *name = buffer_get_string_ret(m, NULL); 274 char *value = buffer_get_string_ret(m, NULL); 275 276 if (name == NULL || value == NULL) { 277 free(name); 278 free(value); 279 goto malf; 280 } 281 debug2("Unrecognised slave extension \"%s\"", name); 282 free(name); 283 free(value); 284 } 285 state->hello_rcvd = 1; 286 return 0; 287 } 288 289 static int 290 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 291 { 292 Channel *nc; 293 struct mux_session_confirm_ctx *cctx; 294 char *reserved, *cmd, *cp; 295 u_int i, j, len, env_len, escape_char, window, packetmax; 296 int new_fd[3]; 297 298 /* Reply for SSHMUX_COMMAND_OPEN */ 299 cctx = xcalloc(1, sizeof(*cctx)); 300 cctx->term = NULL; 301 cctx->rid = rid; 302 cmd = reserved = NULL; 303 cctx->env = NULL; 304 env_len = 0; 305 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 306 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 307 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 308 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 309 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 310 buffer_get_int_ret(&escape_char, m) != 0 || 311 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 312 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 313 malf: 314 free(cmd); 315 free(reserved); 316 for (j = 0; j < env_len; j++) 317 free(cctx->env[j]); 318 free(cctx->env); 319 free(cctx->term); 320 free(cctx); 321 error("%s: malformed message", __func__); 322 return -1; 323 } 324 free(reserved); 325 reserved = NULL; 326 327 while (buffer_len(m) > 0) { 328 #define MUX_MAX_ENV_VARS 4096 329 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 330 goto malf; 331 if (!env_permitted(cp)) { 332 free(cp); 333 continue; 334 } 335 cctx->env = xrealloc(cctx->env, env_len + 2, 336 sizeof(*cctx->env)); 337 cctx->env[env_len++] = cp; 338 cctx->env[env_len] = NULL; 339 if (env_len > MUX_MAX_ENV_VARS) { 340 error(">%d environment variables received, ignoring " 341 "additional", MUX_MAX_ENV_VARS); 342 break; 343 } 344 } 345 346 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 347 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 348 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 349 cctx->want_subsys, cctx->term, cmd, env_len); 350 351 buffer_init(&cctx->cmd); 352 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 353 free(cmd); 354 cmd = NULL; 355 356 /* Gather fds from client */ 357 for(i = 0; i < 3; i++) { 358 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 359 error("%s: failed to receive fd %d from slave", 360 __func__, i); 361 for (j = 0; j < i; j++) 362 close(new_fd[j]); 363 for (j = 0; j < env_len; j++) 364 free(cctx->env[j]); 365 free(cctx->env); 366 free(cctx->term); 367 buffer_free(&cctx->cmd); 368 free(cctx); 369 370 /* prepare reply */ 371 buffer_put_int(r, MUX_S_FAILURE); 372 buffer_put_int(r, rid); 373 buffer_put_cstring(r, 374 "did not receive file descriptors"); 375 return -1; 376 } 377 } 378 379 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 380 new_fd[0], new_fd[1], new_fd[2]); 381 382 /* XXX support multiple child sessions in future */ 383 if (c->remote_id != -1) { 384 debug2("%s: session already open", __func__); 385 /* prepare reply */ 386 buffer_put_int(r, MUX_S_FAILURE); 387 buffer_put_int(r, rid); 388 buffer_put_cstring(r, "Multiple sessions not supported"); 389 cleanup: 390 close(new_fd[0]); 391 close(new_fd[1]); 392 close(new_fd[2]); 393 free(cctx->term); 394 if (env_len != 0) { 395 for (i = 0; i < env_len; i++) 396 free(cctx->env[i]); 397 free(cctx->env); 398 } 399 buffer_free(&cctx->cmd); 400 free(cctx); 401 return 0; 402 } 403 404 if (options.control_master == SSHCTL_MASTER_ASK || 405 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 406 if (!ask_permission("Allow shared connection to %s? ", host)) { 407 debug2("%s: session refused by user", __func__); 408 /* prepare reply */ 409 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 410 buffer_put_int(r, rid); 411 buffer_put_cstring(r, "Permission denied"); 412 goto cleanup; 413 } 414 } 415 416 /* Try to pick up ttymodes from client before it goes raw */ 417 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 418 error("%s: tcgetattr: %s", __func__, strerror(errno)); 419 420 /* enable nonblocking unless tty */ 421 if (!isatty(new_fd[0])) 422 set_nonblock(new_fd[0]); 423 if (!isatty(new_fd[1])) 424 set_nonblock(new_fd[1]); 425 if (!isatty(new_fd[2])) 426 set_nonblock(new_fd[2]); 427 428 window = CHAN_SES_WINDOW_DEFAULT; 429 packetmax = CHAN_SES_PACKET_DEFAULT; 430 if (cctx->want_tty) { 431 window >>= 1; 432 packetmax >>= 1; 433 } 434 435 nc = channel_new("session", SSH_CHANNEL_OPENING, 436 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 437 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 438 439 nc->ctl_chan = c->self; /* link session -> control channel */ 440 c->remote_id = nc->self; /* link control -> session channel */ 441 442 if (cctx->want_tty && escape_char != 0xffffffff) { 443 channel_register_filter(nc->self, 444 client_simple_escape_filter, NULL, 445 client_filter_cleanup, 446 client_new_escape_filter_ctx((int)escape_char)); 447 } 448 449 debug2("%s: channel_new: %d linked to control channel %d", 450 __func__, nc->self, nc->ctl_chan); 451 452 channel_send_open(nc->self); 453 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 454 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 455 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 456 457 /* reply is deferred, sent by mux_session_confirm */ 458 return 0; 459 } 460 461 static int 462 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 463 { 464 debug2("%s: channel %d: alive check", __func__, c->self); 465 466 /* prepare reply */ 467 buffer_put_int(r, MUX_S_ALIVE); 468 buffer_put_int(r, rid); 469 buffer_put_int(r, (u_int)getpid()); 470 471 return 0; 472 } 473 474 static int 475 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 476 { 477 debug2("%s: channel %d: terminate request", __func__, c->self); 478 479 if (options.control_master == SSHCTL_MASTER_ASK || 480 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 481 if (!ask_permission("Terminate shared connection to %s? ", 482 host)) { 483 debug2("%s: termination refused by user", __func__); 484 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 485 buffer_put_int(r, rid); 486 buffer_put_cstring(r, "Permission denied"); 487 return 0; 488 } 489 } 490 491 quit_pending = 1; 492 buffer_put_int(r, MUX_S_OK); 493 buffer_put_int(r, rid); 494 /* XXX exit happens too soon - message never makes it to client */ 495 return 0; 496 } 497 498 static char * 499 format_forward(u_int ftype, Forward *fwd) 500 { 501 char *ret; 502 503 switch (ftype) { 504 case MUX_FWD_LOCAL: 505 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 506 (fwd->listen_host == NULL) ? 507 (options.gateway_ports ? "*" : "LOCALHOST") : 508 fwd->listen_host, fwd->listen_port, 509 fwd->connect_host, fwd->connect_port); 510 break; 511 case MUX_FWD_DYNAMIC: 512 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 513 (fwd->listen_host == NULL) ? 514 (options.gateway_ports ? "*" : "LOCALHOST") : 515 fwd->listen_host, fwd->listen_port); 516 break; 517 case MUX_FWD_REMOTE: 518 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 519 (fwd->listen_host == NULL) ? 520 "LOCALHOST" : fwd->listen_host, 521 fwd->listen_port, 522 fwd->connect_host, fwd->connect_port); 523 break; 524 default: 525 fatal("%s: unknown forward type %u", __func__, ftype); 526 } 527 return ret; 528 } 529 530 static int 531 compare_host(const char *a, const char *b) 532 { 533 if (a == NULL && b == NULL) 534 return 1; 535 if (a == NULL || b == NULL) 536 return 0; 537 return strcmp(a, b) == 0; 538 } 539 540 static int 541 compare_forward(Forward *a, Forward *b) 542 { 543 if (!compare_host(a->listen_host, b->listen_host)) 544 return 0; 545 if (a->listen_port != b->listen_port) 546 return 0; 547 if (!compare_host(a->connect_host, b->connect_host)) 548 return 0; 549 if (a->connect_port != b->connect_port) 550 return 0; 551 552 return 1; 553 } 554 555 static void 556 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 557 { 558 struct mux_channel_confirm_ctx *fctx = ctxt; 559 char *failmsg = NULL; 560 Forward *rfwd; 561 Channel *c; 562 Buffer out; 563 564 if ((c = channel_by_id(fctx->cid)) == NULL) { 565 /* no channel for reply */ 566 error("%s: unknown channel", __func__); 567 return; 568 } 569 buffer_init(&out); 570 if (fctx->fid >= options.num_remote_forwards) { 571 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 572 goto fail; 573 } 574 rfwd = &options.remote_forwards[fctx->fid]; 575 debug("%s: %s for: listen %d, connect %s:%d", __func__, 576 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 577 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); 578 if (type == SSH2_MSG_REQUEST_SUCCESS) { 579 if (rfwd->listen_port == 0) { 580 rfwd->allocated_port = packet_get_int(); 581 logit("Allocated port %u for mux remote forward" 582 " to %s:%d", rfwd->allocated_port, 583 rfwd->connect_host, rfwd->connect_port); 584 buffer_put_int(&out, MUX_S_REMOTE_PORT); 585 buffer_put_int(&out, fctx->rid); 586 buffer_put_int(&out, rfwd->allocated_port); 587 channel_update_permitted_opens(rfwd->handle, 588 rfwd->allocated_port); 589 } else { 590 buffer_put_int(&out, MUX_S_OK); 591 buffer_put_int(&out, fctx->rid); 592 } 593 goto out; 594 } else { 595 if (rfwd->listen_port == 0) 596 channel_update_permitted_opens(rfwd->handle, -1); 597 xasprintf(&failmsg, "remote port forwarding failed for " 598 "listen port %d", rfwd->listen_port); 599 } 600 fail: 601 error("%s: %s", __func__, failmsg); 602 buffer_put_int(&out, MUX_S_FAILURE); 603 buffer_put_int(&out, fctx->rid); 604 buffer_put_cstring(&out, failmsg); 605 free(failmsg); 606 out: 607 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 608 buffer_free(&out); 609 if (c->mux_pause <= 0) 610 fatal("%s: mux_pause %d", __func__, c->mux_pause); 611 c->mux_pause = 0; /* start processing messages again */ 612 } 613 614 static int 615 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 616 { 617 Forward fwd; 618 char *fwd_desc = NULL; 619 u_int ftype; 620 u_int lport, cport; 621 int i, ret = 0, freefwd = 1; 622 623 fwd.listen_host = fwd.connect_host = NULL; 624 if (buffer_get_int_ret(&ftype, m) != 0 || 625 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 626 buffer_get_int_ret(&lport, m) != 0 || 627 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 628 buffer_get_int_ret(&cport, m) != 0 || 629 lport > 65535 || cport > 65535) { 630 error("%s: malformed message", __func__); 631 ret = -1; 632 goto out; 633 } 634 fwd.listen_port = lport; 635 fwd.connect_port = cport; 636 if (*fwd.listen_host == '\0') { 637 free(fwd.listen_host); 638 fwd.listen_host = NULL; 639 } 640 if (*fwd.connect_host == '\0') { 641 free(fwd.connect_host); 642 fwd.connect_host = NULL; 643 } 644 645 debug2("%s: channel %d: request %s", __func__, c->self, 646 (fwd_desc = format_forward(ftype, &fwd))); 647 648 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 649 ftype != MUX_FWD_DYNAMIC) { 650 logit("%s: invalid forwarding type %u", __func__, ftype); 651 invalid: 652 free(fwd.listen_host); 653 free(fwd.connect_host); 654 buffer_put_int(r, MUX_S_FAILURE); 655 buffer_put_int(r, rid); 656 buffer_put_cstring(r, "Invalid forwarding request"); 657 return 0; 658 } 659 if (fwd.listen_port >= 65536) { 660 logit("%s: invalid listen port %u", __func__, 661 fwd.listen_port); 662 goto invalid; 663 } 664 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC && 665 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 666 logit("%s: invalid connect port %u", __func__, 667 fwd.connect_port); 668 goto invalid; 669 } 670 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) { 671 logit("%s: missing connect host", __func__); 672 goto invalid; 673 } 674 675 /* Skip forwards that have already been requested */ 676 switch (ftype) { 677 case MUX_FWD_LOCAL: 678 case MUX_FWD_DYNAMIC: 679 for (i = 0; i < options.num_local_forwards; i++) { 680 if (compare_forward(&fwd, 681 options.local_forwards + i)) { 682 exists: 683 debug2("%s: found existing forwarding", 684 __func__); 685 buffer_put_int(r, MUX_S_OK); 686 buffer_put_int(r, rid); 687 goto out; 688 } 689 } 690 break; 691 case MUX_FWD_REMOTE: 692 for (i = 0; i < options.num_remote_forwards; i++) { 693 if (compare_forward(&fwd, 694 options.remote_forwards + i)) { 695 if (fwd.listen_port != 0) 696 goto exists; 697 debug2("%s: found allocated port", 698 __func__); 699 buffer_put_int(r, MUX_S_REMOTE_PORT); 700 buffer_put_int(r, rid); 701 buffer_put_int(r, 702 options.remote_forwards[i].allocated_port); 703 goto out; 704 } 705 } 706 break; 707 } 708 709 if (options.control_master == SSHCTL_MASTER_ASK || 710 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 711 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 712 debug2("%s: forwarding refused by user", __func__); 713 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 714 buffer_put_int(r, rid); 715 buffer_put_cstring(r, "Permission denied"); 716 goto out; 717 } 718 } 719 720 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 721 if (!channel_setup_local_fwd_listener(fwd.listen_host, 722 fwd.listen_port, fwd.connect_host, fwd.connect_port, 723 options.gateway_ports)) { 724 fail: 725 logit("slave-requested %s failed", fwd_desc); 726 buffer_put_int(r, MUX_S_FAILURE); 727 buffer_put_int(r, rid); 728 buffer_put_cstring(r, "Port forwarding failed"); 729 goto out; 730 } 731 add_local_forward(&options, &fwd); 732 freefwd = 0; 733 } else { 734 struct mux_channel_confirm_ctx *fctx; 735 736 fwd.handle = channel_request_remote_forwarding(fwd.listen_host, 737 fwd.listen_port, fwd.connect_host, fwd.connect_port); 738 if (fwd.handle < 0) 739 goto fail; 740 add_remote_forward(&options, &fwd); 741 fctx = xcalloc(1, sizeof(*fctx)); 742 fctx->cid = c->self; 743 fctx->rid = rid; 744 fctx->fid = options.num_remote_forwards - 1; 745 client_register_global_confirm(mux_confirm_remote_forward, 746 fctx); 747 freefwd = 0; 748 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 749 /* delayed reply in mux_confirm_remote_forward */ 750 goto out; 751 } 752 buffer_put_int(r, MUX_S_OK); 753 buffer_put_int(r, rid); 754 out: 755 free(fwd_desc); 756 if (freefwd) { 757 free(fwd.listen_host); 758 free(fwd.connect_host); 759 } 760 return ret; 761 } 762 763 static int 764 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 765 { 766 Forward fwd, *found_fwd; 767 char *fwd_desc = NULL; 768 const char *error_reason = NULL; 769 u_int ftype; 770 int i, listen_port, ret = 0; 771 u_int lport, cport; 772 773 fwd.listen_host = fwd.connect_host = NULL; 774 if (buffer_get_int_ret(&ftype, m) != 0 || 775 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 776 buffer_get_int_ret(&lport, m) != 0 || 777 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 778 buffer_get_int_ret(&cport, m) != 0 || 779 lport > 65535 || cport > 65535) { 780 error("%s: malformed message", __func__); 781 ret = -1; 782 goto out; 783 } 784 fwd.listen_port = lport; 785 fwd.connect_port = cport; 786 787 if (*fwd.listen_host == '\0') { 788 free(fwd.listen_host); 789 fwd.listen_host = NULL; 790 } 791 if (*fwd.connect_host == '\0') { 792 free(fwd.connect_host); 793 fwd.connect_host = NULL; 794 } 795 796 debug2("%s: channel %d: request cancel %s", __func__, c->self, 797 (fwd_desc = format_forward(ftype, &fwd))); 798 799 /* make sure this has been requested */ 800 found_fwd = NULL; 801 switch (ftype) { 802 case MUX_FWD_LOCAL: 803 case MUX_FWD_DYNAMIC: 804 for (i = 0; i < options.num_local_forwards; i++) { 805 if (compare_forward(&fwd, 806 options.local_forwards + i)) { 807 found_fwd = options.local_forwards + i; 808 break; 809 } 810 } 811 break; 812 case MUX_FWD_REMOTE: 813 for (i = 0; i < options.num_remote_forwards; i++) { 814 if (compare_forward(&fwd, 815 options.remote_forwards + i)) { 816 found_fwd = options.remote_forwards + i; 817 break; 818 } 819 } 820 break; 821 } 822 823 if (found_fwd == NULL) 824 error_reason = "port not forwarded"; 825 else if (ftype == MUX_FWD_REMOTE) { 826 /* 827 * This shouldn't fail unless we confused the host/port 828 * between options.remote_forwards and permitted_opens. 829 * However, for dynamic allocated listen ports we need 830 * to lookup the actual listen port. 831 */ 832 listen_port = (fwd.listen_port == 0) ? 833 found_fwd->allocated_port : fwd.listen_port; 834 if (channel_request_rforward_cancel(fwd.listen_host, 835 listen_port) == -1) 836 error_reason = "port not in permitted opens"; 837 } else { /* local and dynamic forwards */ 838 /* Ditto */ 839 if (channel_cancel_lport_listener(fwd.listen_host, 840 fwd.listen_port, fwd.connect_port, 841 options.gateway_ports) == -1) 842 error_reason = "port not found"; 843 } 844 845 if (error_reason == NULL) { 846 buffer_put_int(r, MUX_S_OK); 847 buffer_put_int(r, rid); 848 849 free(found_fwd->listen_host); 850 free(found_fwd->connect_host); 851 found_fwd->listen_host = found_fwd->connect_host = NULL; 852 found_fwd->listen_port = found_fwd->connect_port = 0; 853 } else { 854 buffer_put_int(r, MUX_S_FAILURE); 855 buffer_put_int(r, rid); 856 buffer_put_cstring(r, error_reason); 857 } 858 out: 859 free(fwd_desc); 860 free(fwd.listen_host); 861 free(fwd.connect_host); 862 863 return ret; 864 } 865 866 static int 867 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 868 { 869 Channel *nc; 870 char *reserved, *chost; 871 u_int cport, i, j; 872 int new_fd[2]; 873 874 chost = reserved = NULL; 875 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 876 (chost = buffer_get_string_ret(m, NULL)) == NULL || 877 buffer_get_int_ret(&cport, m) != 0) { 878 free(reserved); 879 free(chost); 880 error("%s: malformed message", __func__); 881 return -1; 882 } 883 free(reserved); 884 885 debug2("%s: channel %d: request stdio fwd to %s:%u", 886 __func__, c->self, chost, cport); 887 888 /* Gather fds from client */ 889 for(i = 0; i < 2; i++) { 890 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 891 error("%s: failed to receive fd %d from slave", 892 __func__, i); 893 for (j = 0; j < i; j++) 894 close(new_fd[j]); 895 free(chost); 896 897 /* prepare reply */ 898 buffer_put_int(r, MUX_S_FAILURE); 899 buffer_put_int(r, rid); 900 buffer_put_cstring(r, 901 "did not receive file descriptors"); 902 return -1; 903 } 904 } 905 906 debug3("%s: got fds stdin %d, stdout %d", __func__, 907 new_fd[0], new_fd[1]); 908 909 /* XXX support multiple child sessions in future */ 910 if (c->remote_id != -1) { 911 debug2("%s: session already open", __func__); 912 /* prepare reply */ 913 buffer_put_int(r, MUX_S_FAILURE); 914 buffer_put_int(r, rid); 915 buffer_put_cstring(r, "Multiple sessions not supported"); 916 cleanup: 917 close(new_fd[0]); 918 close(new_fd[1]); 919 free(chost); 920 return 0; 921 } 922 923 if (options.control_master == SSHCTL_MASTER_ASK || 924 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 925 if (!ask_permission("Allow forward to %s:%u? ", 926 chost, cport)) { 927 debug2("%s: stdio fwd refused by user", __func__); 928 /* prepare reply */ 929 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 930 buffer_put_int(r, rid); 931 buffer_put_cstring(r, "Permission denied"); 932 goto cleanup; 933 } 934 } 935 936 /* enable nonblocking unless tty */ 937 if (!isatty(new_fd[0])) 938 set_nonblock(new_fd[0]); 939 if (!isatty(new_fd[1])) 940 set_nonblock(new_fd[1]); 941 942 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 943 944 nc->ctl_chan = c->self; /* link session -> control channel */ 945 c->remote_id = nc->self; /* link control -> session channel */ 946 947 debug2("%s: channel_new: %d linked to control channel %d", 948 __func__, nc->self, nc->ctl_chan); 949 950 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 951 952 /* prepare reply */ 953 /* XXX defer until channel confirmed */ 954 buffer_put_int(r, MUX_S_SESSION_OPENED); 955 buffer_put_int(r, rid); 956 buffer_put_int(r, nc->self); 957 958 return 0; 959 } 960 961 static int 962 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 963 { 964 debug("%s: channel %d: stop listening", __func__, c->self); 965 966 if (options.control_master == SSHCTL_MASTER_ASK || 967 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 968 if (!ask_permission("Disable further multiplexing on shared " 969 "connection to %s? ", host)) { 970 debug2("%s: stop listen refused by user", __func__); 971 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 972 buffer_put_int(r, rid); 973 buffer_put_cstring(r, "Permission denied"); 974 return 0; 975 } 976 } 977 978 if (mux_listener_channel != NULL) { 979 channel_free(mux_listener_channel); 980 client_stop_mux(); 981 free(options.control_path); 982 options.control_path = NULL; 983 mux_listener_channel = NULL; 984 muxserver_sock = -1; 985 } 986 987 /* prepare reply */ 988 buffer_put_int(r, MUX_S_OK); 989 buffer_put_int(r, rid); 990 991 return 0; 992 } 993 994 /* Channel callbacks fired on read/write from mux slave fd */ 995 static int 996 mux_master_read_cb(Channel *c) 997 { 998 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 999 Buffer in, out; 1000 void *ptr; 1001 u_int type, rid, have, i; 1002 int ret = -1; 1003 1004 /* Setup ctx and */ 1005 if (c->mux_ctx == NULL) { 1006 state = xcalloc(1, sizeof(*state)); 1007 c->mux_ctx = state; 1008 channel_register_cleanup(c->self, 1009 mux_master_control_cleanup_cb, 0); 1010 1011 /* Send hello */ 1012 buffer_init(&out); 1013 buffer_put_int(&out, MUX_MSG_HELLO); 1014 buffer_put_int(&out, SSHMUX_VER); 1015 /* no extensions */ 1016 buffer_put_string(&c->output, buffer_ptr(&out), 1017 buffer_len(&out)); 1018 buffer_free(&out); 1019 debug3("%s: channel %d: hello sent", __func__, c->self); 1020 return 0; 1021 } 1022 1023 buffer_init(&in); 1024 buffer_init(&out); 1025 1026 /* Channel code ensures that we receive whole packets */ 1027 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1028 malf: 1029 error("%s: malformed message", __func__); 1030 goto out; 1031 } 1032 buffer_append(&in, ptr, have); 1033 1034 if (buffer_get_int_ret(&type, &in) != 0) 1035 goto malf; 1036 debug3("%s: channel %d packet type 0x%08x len %u", 1037 __func__, c->self, type, buffer_len(&in)); 1038 1039 if (type == MUX_MSG_HELLO) 1040 rid = 0; 1041 else { 1042 if (!state->hello_rcvd) { 1043 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1044 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1045 goto out; 1046 } 1047 if (buffer_get_int_ret(&rid, &in) != 0) 1048 goto malf; 1049 } 1050 1051 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1052 if (type == mux_master_handlers[i].type) { 1053 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1054 break; 1055 } 1056 } 1057 if (mux_master_handlers[i].handler == NULL) { 1058 error("%s: unsupported mux message 0x%08x", __func__, type); 1059 buffer_put_int(&out, MUX_S_FAILURE); 1060 buffer_put_int(&out, rid); 1061 buffer_put_cstring(&out, "unsupported request"); 1062 ret = 0; 1063 } 1064 /* Enqueue reply packet */ 1065 if (buffer_len(&out) != 0) { 1066 buffer_put_string(&c->output, buffer_ptr(&out), 1067 buffer_len(&out)); 1068 } 1069 out: 1070 buffer_free(&in); 1071 buffer_free(&out); 1072 return ret; 1073 } 1074 1075 void 1076 mux_exit_message(Channel *c, int exitval) 1077 { 1078 Buffer m; 1079 Channel *mux_chan; 1080 1081 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1082 exitval); 1083 1084 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1085 fatal("%s: channel %d missing mux channel %d", 1086 __func__, c->self, c->ctl_chan); 1087 1088 /* Append exit message packet to control socket output queue */ 1089 buffer_init(&m); 1090 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1091 buffer_put_int(&m, c->self); 1092 buffer_put_int(&m, exitval); 1093 1094 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1095 buffer_free(&m); 1096 } 1097 1098 void 1099 mux_tty_alloc_failed(Channel *c) 1100 { 1101 Buffer m; 1102 Channel *mux_chan; 1103 1104 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1105 1106 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1107 fatal("%s: channel %d missing mux channel %d", 1108 __func__, c->self, c->ctl_chan); 1109 1110 /* Append exit message packet to control socket output queue */ 1111 buffer_init(&m); 1112 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1113 buffer_put_int(&m, c->self); 1114 1115 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1116 buffer_free(&m); 1117 } 1118 1119 /* Prepare a mux master to listen on a Unix domain socket. */ 1120 void 1121 muxserver_listen(void) 1122 { 1123 struct sockaddr_un addr; 1124 mode_t old_umask; 1125 char *orig_control_path = options.control_path; 1126 char rbuf[16+1]; 1127 u_int i, r; 1128 1129 if (options.control_path == NULL || 1130 options.control_master == SSHCTL_MASTER_NO) 1131 return; 1132 1133 debug("setting up multiplex master socket"); 1134 1135 /* 1136 * Use a temporary path before listen so we can pseudo-atomically 1137 * establish the listening socket in its final location to avoid 1138 * other processes racing in between bind() and listen() and hitting 1139 * an unready socket. 1140 */ 1141 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1142 r = arc4random_uniform(26+26+10); 1143 rbuf[i] = (r < 26) ? 'a' + r : 1144 (r < 26*2) ? 'A' + r - 26 : 1145 '0' + r - 26 - 26; 1146 } 1147 rbuf[sizeof(rbuf) - 1] = '\0'; 1148 options.control_path = NULL; 1149 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1150 debug3("%s: temporary control path %s", __func__, options.control_path); 1151 1152 memset(&addr, '\0', sizeof(addr)); 1153 addr.sun_family = AF_UNIX; 1154 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 1155 strlen(options.control_path) + 1; 1156 1157 if (strlcpy(addr.sun_path, options.control_path, 1158 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) { 1159 error("ControlPath \"%s\" too long for Unix domain socket", 1160 options.control_path); 1161 goto disable_mux_master; 1162 } 1163 1164 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1165 fatal("%s socket(): %s", __func__, strerror(errno)); 1166 1167 old_umask = umask(0177); 1168 if (bind(muxserver_sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 1169 if (errno == EINVAL || errno == EADDRINUSE) { 1170 error("ControlSocket %s already exists, " 1171 "disabling multiplexing", options.control_path); 1172 disable_mux_master: 1173 if (muxserver_sock != -1) { 1174 close(muxserver_sock); 1175 muxserver_sock = -1; 1176 } 1177 free(orig_control_path); 1178 free(options.control_path); 1179 options.control_path = NULL; 1180 options.control_master = SSHCTL_MASTER_NO; 1181 return; 1182 } else 1183 fatal("%s bind(): %s", __func__, strerror(errno)); 1184 } 1185 umask(old_umask); 1186 1187 if (listen(muxserver_sock, 64) == -1) 1188 fatal("%s listen(): %s", __func__, strerror(errno)); 1189 1190 /* Now atomically "move" the mux socket into position */ 1191 if (link(options.control_path, orig_control_path) != 0) { 1192 if (errno != EEXIST) { 1193 fatal("%s: link mux listener %s => %s: %s", __func__, 1194 options.control_path, orig_control_path, 1195 strerror(errno)); 1196 } 1197 error("ControlSocket %s already exists, disabling multiplexing", 1198 orig_control_path); 1199 unlink(options.control_path); 1200 goto disable_mux_master; 1201 } 1202 unlink(options.control_path); 1203 free(options.control_path); 1204 options.control_path = orig_control_path; 1205 1206 set_nonblock(muxserver_sock); 1207 1208 mux_listener_channel = channel_new("mux listener", 1209 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1210 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1211 0, options.control_path, 1); 1212 mux_listener_channel->mux_rcb = mux_master_read_cb; 1213 debug3("%s: mux listener channel %d fd %d", __func__, 1214 mux_listener_channel->self, mux_listener_channel->sock); 1215 } 1216 1217 /* Callback on open confirmation in mux master for a mux client session. */ 1218 static void 1219 mux_session_confirm(int id, int success, void *arg) 1220 { 1221 struct mux_session_confirm_ctx *cctx = arg; 1222 const char *display; 1223 Channel *c, *cc; 1224 int i; 1225 Buffer reply; 1226 1227 if (cctx == NULL) 1228 fatal("%s: cctx == NULL", __func__); 1229 if ((c = channel_by_id(id)) == NULL) 1230 fatal("%s: no channel for id %d", __func__, id); 1231 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1232 fatal("%s: channel %d lacks control channel %d", __func__, 1233 id, c->ctl_chan); 1234 1235 if (!success) { 1236 debug3("%s: sending failure reply", __func__); 1237 /* prepare reply */ 1238 buffer_init(&reply); 1239 buffer_put_int(&reply, MUX_S_FAILURE); 1240 buffer_put_int(&reply, cctx->rid); 1241 buffer_put_cstring(&reply, "Session open refused by peer"); 1242 goto done; 1243 } 1244 1245 display = getenv("DISPLAY"); 1246 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1247 char *proto, *data; 1248 1249 /* Get reasonable local authentication information. */ 1250 client_x11_get_proto(display, options.xauth_location, 1251 options.forward_x11_trusted, options.forward_x11_timeout, 1252 &proto, &data); 1253 /* Request forwarding with authentication spoofing. */ 1254 debug("Requesting X11 forwarding with authentication " 1255 "spoofing."); 1256 x11_request_forwarding_with_spoofing(id, display, proto, 1257 data, 1); 1258 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1259 /* XXX exit_on_forward_failure */ 1260 } 1261 1262 if (cctx->want_agent_fwd && options.forward_agent) { 1263 debug("Requesting authentication agent forwarding."); 1264 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1265 packet_send(); 1266 } 1267 1268 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1269 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1270 1271 debug3("%s: sending success reply", __func__); 1272 /* prepare reply */ 1273 buffer_init(&reply); 1274 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1275 buffer_put_int(&reply, cctx->rid); 1276 buffer_put_int(&reply, c->self); 1277 1278 done: 1279 /* Send reply */ 1280 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1281 buffer_free(&reply); 1282 1283 if (cc->mux_pause <= 0) 1284 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1285 cc->mux_pause = 0; /* start processing messages again */ 1286 c->open_confirm_ctx = NULL; 1287 buffer_free(&cctx->cmd); 1288 free(cctx->term); 1289 if (cctx->env != NULL) { 1290 for (i = 0; cctx->env[i] != NULL; i++) 1291 free(cctx->env[i]); 1292 free(cctx->env); 1293 } 1294 free(cctx); 1295 } 1296 1297 /* ** Multiplexing client support */ 1298 1299 /* Exit signal handler */ 1300 static void 1301 control_client_sighandler(int signo) 1302 { 1303 muxclient_terminate = signo; 1304 } 1305 1306 /* 1307 * Relay signal handler - used to pass some signals from mux client to 1308 * mux master. 1309 */ 1310 static void 1311 control_client_sigrelay(int signo) 1312 { 1313 int save_errno = errno; 1314 1315 if (muxserver_pid > 1) 1316 kill(muxserver_pid, signo); 1317 1318 errno = save_errno; 1319 } 1320 1321 static int 1322 mux_client_read(int fd, Buffer *b, u_int need) 1323 { 1324 u_int have; 1325 ssize_t len; 1326 u_char *p; 1327 struct pollfd pfd; 1328 1329 pfd.fd = fd; 1330 pfd.events = POLLIN; 1331 p = buffer_append_space(b, need); 1332 for (have = 0; have < need; ) { 1333 if (muxclient_terminate) { 1334 errno = EINTR; 1335 return -1; 1336 } 1337 len = read(fd, p + have, need - have); 1338 if (len < 0) { 1339 switch (errno) { 1340 case EAGAIN: 1341 (void)poll(&pfd, 1, -1); 1342 /* FALLTHROUGH */ 1343 case EINTR: 1344 continue; 1345 default: 1346 return -1; 1347 } 1348 } 1349 if (len == 0) { 1350 errno = EPIPE; 1351 return -1; 1352 } 1353 have += (u_int)len; 1354 } 1355 return 0; 1356 } 1357 1358 static int 1359 mux_client_write_packet(int fd, Buffer *m) 1360 { 1361 Buffer queue; 1362 u_int have, need; 1363 int oerrno, len; 1364 u_char *ptr; 1365 struct pollfd pfd; 1366 1367 pfd.fd = fd; 1368 pfd.events = POLLOUT; 1369 buffer_init(&queue); 1370 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1371 1372 need = buffer_len(&queue); 1373 ptr = buffer_ptr(&queue); 1374 1375 for (have = 0; have < need; ) { 1376 if (muxclient_terminate) { 1377 buffer_free(&queue); 1378 errno = EINTR; 1379 return -1; 1380 } 1381 len = write(fd, ptr + have, need - have); 1382 if (len < 0) { 1383 switch (errno) { 1384 case EAGAIN: 1385 (void)poll(&pfd, 1, -1); 1386 /* FALLTHROUGH */ 1387 case EINTR: 1388 continue; 1389 default: 1390 oerrno = errno; 1391 buffer_free(&queue); 1392 errno = oerrno; 1393 return -1; 1394 } 1395 } 1396 if (len == 0) { 1397 buffer_free(&queue); 1398 errno = EPIPE; 1399 return -1; 1400 } 1401 have += (u_int)len; 1402 } 1403 buffer_free(&queue); 1404 return 0; 1405 } 1406 1407 static int 1408 mux_client_read_packet(int fd, Buffer *m) 1409 { 1410 Buffer queue; 1411 u_int need, have; 1412 void *ptr; 1413 int oerrno; 1414 1415 buffer_init(&queue); 1416 if (mux_client_read(fd, &queue, 4) != 0) { 1417 if ((oerrno = errno) == EPIPE) 1418 debug3("%s: read header failed: %s", __func__, 1419 strerror(errno)); 1420 buffer_free(&queue); 1421 errno = oerrno; 1422 return -1; 1423 } 1424 need = get_u32(buffer_ptr(&queue)); 1425 if (mux_client_read(fd, &queue, need) != 0) { 1426 oerrno = errno; 1427 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1428 buffer_free(&queue); 1429 errno = oerrno; 1430 return -1; 1431 } 1432 ptr = buffer_get_string_ptr(&queue, &have); 1433 buffer_append(m, ptr, have); 1434 buffer_free(&queue); 1435 return 0; 1436 } 1437 1438 static int 1439 mux_client_hello_exchange(int fd) 1440 { 1441 Buffer m; 1442 u_int type, ver; 1443 1444 buffer_init(&m); 1445 buffer_put_int(&m, MUX_MSG_HELLO); 1446 buffer_put_int(&m, SSHMUX_VER); 1447 /* no extensions */ 1448 1449 if (mux_client_write_packet(fd, &m) != 0) 1450 fatal("%s: write packet: %s", __func__, strerror(errno)); 1451 1452 buffer_clear(&m); 1453 1454 /* Read their HELLO */ 1455 if (mux_client_read_packet(fd, &m) != 0) { 1456 buffer_free(&m); 1457 return -1; 1458 } 1459 1460 type = buffer_get_int(&m); 1461 if (type != MUX_MSG_HELLO) 1462 fatal("%s: expected HELLO (%u) received %u", 1463 __func__, MUX_MSG_HELLO, type); 1464 ver = buffer_get_int(&m); 1465 if (ver != SSHMUX_VER) 1466 fatal("Unsupported multiplexing protocol version %d " 1467 "(expected %d)", ver, SSHMUX_VER); 1468 debug2("%s: master version %u", __func__, ver); 1469 /* No extensions are presently defined */ 1470 while (buffer_len(&m) > 0) { 1471 char *name = buffer_get_string(&m, NULL); 1472 char *value = buffer_get_string(&m, NULL); 1473 1474 debug2("Unrecognised master extension \"%s\"", name); 1475 free(name); 1476 free(value); 1477 } 1478 buffer_free(&m); 1479 return 0; 1480 } 1481 1482 static u_int 1483 mux_client_request_alive(int fd) 1484 { 1485 Buffer m; 1486 char *e; 1487 u_int pid, type, rid; 1488 1489 debug3("%s: entering", __func__); 1490 1491 buffer_init(&m); 1492 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1493 buffer_put_int(&m, muxclient_request_id); 1494 1495 if (mux_client_write_packet(fd, &m) != 0) 1496 fatal("%s: write packet: %s", __func__, strerror(errno)); 1497 1498 buffer_clear(&m); 1499 1500 /* Read their reply */ 1501 if (mux_client_read_packet(fd, &m) != 0) { 1502 buffer_free(&m); 1503 return 0; 1504 } 1505 1506 type = buffer_get_int(&m); 1507 if (type != MUX_S_ALIVE) { 1508 e = buffer_get_string(&m, NULL); 1509 fatal("%s: master returned error: %s", __func__, e); 1510 } 1511 1512 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1513 fatal("%s: out of sequence reply: my id %u theirs %u", 1514 __func__, muxclient_request_id, rid); 1515 pid = buffer_get_int(&m); 1516 buffer_free(&m); 1517 1518 debug3("%s: done pid = %u", __func__, pid); 1519 1520 muxclient_request_id++; 1521 1522 return pid; 1523 } 1524 1525 static void 1526 mux_client_request_terminate(int fd) 1527 { 1528 Buffer m; 1529 char *e; 1530 u_int type, rid; 1531 1532 debug3("%s: entering", __func__); 1533 1534 buffer_init(&m); 1535 buffer_put_int(&m, MUX_C_TERMINATE); 1536 buffer_put_int(&m, muxclient_request_id); 1537 1538 if (mux_client_write_packet(fd, &m) != 0) 1539 fatal("%s: write packet: %s", __func__, strerror(errno)); 1540 1541 buffer_clear(&m); 1542 1543 /* Read their reply */ 1544 if (mux_client_read_packet(fd, &m) != 0) { 1545 /* Remote end exited already */ 1546 if (errno == EPIPE) { 1547 buffer_free(&m); 1548 return; 1549 } 1550 fatal("%s: read from master failed: %s", 1551 __func__, strerror(errno)); 1552 } 1553 1554 type = buffer_get_int(&m); 1555 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1556 fatal("%s: out of sequence reply: my id %u theirs %u", 1557 __func__, muxclient_request_id, rid); 1558 switch (type) { 1559 case MUX_S_OK: 1560 break; 1561 case MUX_S_PERMISSION_DENIED: 1562 e = buffer_get_string(&m, NULL); 1563 fatal("Master refused termination request: %s", e); 1564 case MUX_S_FAILURE: 1565 e = buffer_get_string(&m, NULL); 1566 fatal("%s: termination request failed: %s", __func__, e); 1567 default: 1568 fatal("%s: unexpected response from master 0x%08x", 1569 __func__, type); 1570 } 1571 buffer_free(&m); 1572 muxclient_request_id++; 1573 } 1574 1575 static int 1576 mux_client_forward(int fd, int cancel_flag, u_int ftype, Forward *fwd) 1577 { 1578 Buffer m; 1579 char *e, *fwd_desc; 1580 u_int type, rid; 1581 1582 fwd_desc = format_forward(ftype, fwd); 1583 debug("Requesting %s %s", 1584 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1585 free(fwd_desc); 1586 1587 buffer_init(&m); 1588 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1589 buffer_put_int(&m, muxclient_request_id); 1590 buffer_put_int(&m, ftype); 1591 buffer_put_cstring(&m, 1592 fwd->listen_host == NULL ? "" : fwd->listen_host); 1593 buffer_put_int(&m, fwd->listen_port); 1594 buffer_put_cstring(&m, 1595 fwd->connect_host == NULL ? "" : fwd->connect_host); 1596 buffer_put_int(&m, fwd->connect_port); 1597 1598 if (mux_client_write_packet(fd, &m) != 0) 1599 fatal("%s: write packet: %s", __func__, strerror(errno)); 1600 1601 buffer_clear(&m); 1602 1603 /* Read their reply */ 1604 if (mux_client_read_packet(fd, &m) != 0) { 1605 buffer_free(&m); 1606 return -1; 1607 } 1608 1609 type = buffer_get_int(&m); 1610 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1611 fatal("%s: out of sequence reply: my id %u theirs %u", 1612 __func__, muxclient_request_id, rid); 1613 switch (type) { 1614 case MUX_S_OK: 1615 break; 1616 case MUX_S_REMOTE_PORT: 1617 if (cancel_flag) 1618 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1619 fwd->allocated_port = buffer_get_int(&m); 1620 logit("Allocated port %u for remote forward to %s:%d", 1621 fwd->allocated_port, 1622 fwd->connect_host ? fwd->connect_host : "", 1623 fwd->connect_port); 1624 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1625 fprintf(stdout, "%u\n", fwd->allocated_port); 1626 break; 1627 case MUX_S_PERMISSION_DENIED: 1628 e = buffer_get_string(&m, NULL); 1629 buffer_free(&m); 1630 error("Master refused forwarding request: %s", e); 1631 return -1; 1632 case MUX_S_FAILURE: 1633 e = buffer_get_string(&m, NULL); 1634 buffer_free(&m); 1635 error("%s: forwarding request failed: %s", __func__, e); 1636 return -1; 1637 default: 1638 fatal("%s: unexpected response from master 0x%08x", 1639 __func__, type); 1640 } 1641 buffer_free(&m); 1642 1643 muxclient_request_id++; 1644 return 0; 1645 } 1646 1647 static int 1648 mux_client_forwards(int fd, int cancel_flag) 1649 { 1650 int i, ret = 0; 1651 1652 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1653 cancel_flag ? "cancel" : "request", 1654 options.num_local_forwards, options.num_remote_forwards); 1655 1656 /* XXX ExitOnForwardingFailure */ 1657 for (i = 0; i < options.num_local_forwards; i++) { 1658 if (mux_client_forward(fd, cancel_flag, 1659 options.local_forwards[i].connect_port == 0 ? 1660 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1661 options.local_forwards + i) != 0) 1662 ret = -1; 1663 } 1664 for (i = 0; i < options.num_remote_forwards; i++) { 1665 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1666 options.remote_forwards + i) != 0) 1667 ret = -1; 1668 } 1669 return ret; 1670 } 1671 1672 static int 1673 mux_client_request_session(int fd) 1674 { 1675 Buffer m; 1676 char *e, *term; 1677 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1678 extern char **environ; 1679 int devnull, rawmode; 1680 1681 debug3("%s: entering", __func__); 1682 1683 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1684 error("%s: master alive request failed", __func__); 1685 return -1; 1686 } 1687 1688 signal(SIGPIPE, SIG_IGN); 1689 1690 if (stdin_null_flag) { 1691 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1692 fatal("open(/dev/null): %s", strerror(errno)); 1693 if (dup2(devnull, STDIN_FILENO) == -1) 1694 fatal("dup2: %s", strerror(errno)); 1695 if (devnull > STDERR_FILENO) 1696 close(devnull); 1697 } 1698 1699 term = getenv("TERM"); 1700 1701 buffer_init(&m); 1702 buffer_put_int(&m, MUX_C_NEW_SESSION); 1703 buffer_put_int(&m, muxclient_request_id); 1704 buffer_put_cstring(&m, ""); /* reserved */ 1705 buffer_put_int(&m, tty_flag); 1706 buffer_put_int(&m, options.forward_x11); 1707 buffer_put_int(&m, options.forward_agent); 1708 buffer_put_int(&m, subsystem_flag); 1709 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1710 0xffffffff : (u_int)options.escape_char); 1711 buffer_put_cstring(&m, term == NULL ? "" : term); 1712 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1713 1714 if (options.num_send_env > 0 && environ != NULL) { 1715 /* Pass environment */ 1716 for (i = 0; environ[i] != NULL; i++) { 1717 if (env_permitted(environ[i])) { 1718 buffer_put_cstring(&m, environ[i]); 1719 } 1720 } 1721 } 1722 1723 if (mux_client_write_packet(fd, &m) != 0) 1724 fatal("%s: write packet: %s", __func__, strerror(errno)); 1725 1726 /* Send the stdio file descriptors */ 1727 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1728 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1729 mm_send_fd(fd, STDERR_FILENO) == -1) 1730 fatal("%s: send fds failed", __func__); 1731 1732 debug3("%s: session request sent", __func__); 1733 1734 /* Read their reply */ 1735 buffer_clear(&m); 1736 if (mux_client_read_packet(fd, &m) != 0) { 1737 error("%s: read from master failed: %s", 1738 __func__, strerror(errno)); 1739 buffer_free(&m); 1740 return -1; 1741 } 1742 1743 type = buffer_get_int(&m); 1744 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1745 fatal("%s: out of sequence reply: my id %u theirs %u", 1746 __func__, muxclient_request_id, rid); 1747 switch (type) { 1748 case MUX_S_SESSION_OPENED: 1749 sid = buffer_get_int(&m); 1750 debug("%s: master session id: %u", __func__, sid); 1751 break; 1752 case MUX_S_PERMISSION_DENIED: 1753 e = buffer_get_string(&m, NULL); 1754 buffer_free(&m); 1755 error("Master refused session 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: session request failed: %s", __func__, e); 1761 return -1; 1762 default: 1763 buffer_free(&m); 1764 error("%s: unexpected response from master 0x%08x", 1765 __func__, type); 1766 return -1; 1767 } 1768 muxclient_request_id++; 1769 1770 signal(SIGHUP, control_client_sighandler); 1771 signal(SIGINT, control_client_sighandler); 1772 signal(SIGTERM, control_client_sighandler); 1773 signal(SIGWINCH, control_client_sigrelay); 1774 1775 rawmode = tty_flag; 1776 if (tty_flag) 1777 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1778 1779 /* 1780 * Stick around until the controlee closes the client_fd. 1781 * Before it does, it is expected to write an exit message. 1782 * This process must read the value and wait for the closure of 1783 * the client_fd; if this one closes early, the multiplex master will 1784 * terminate early too (possibly losing data). 1785 */ 1786 for (exitval = 255, exitval_seen = 0;;) { 1787 buffer_clear(&m); 1788 if (mux_client_read_packet(fd, &m) != 0) 1789 break; 1790 type = buffer_get_int(&m); 1791 switch (type) { 1792 case MUX_S_TTY_ALLOC_FAIL: 1793 if ((esid = buffer_get_int(&m)) != sid) 1794 fatal("%s: tty alloc fail on unknown session: " 1795 "my id %u theirs %u", 1796 __func__, sid, esid); 1797 leave_raw_mode(options.request_tty == 1798 REQUEST_TTY_FORCE); 1799 rawmode = 0; 1800 continue; 1801 case MUX_S_EXIT_MESSAGE: 1802 if ((esid = buffer_get_int(&m)) != sid) 1803 fatal("%s: exit on unknown session: " 1804 "my id %u theirs %u", 1805 __func__, sid, esid); 1806 if (exitval_seen) 1807 fatal("%s: exitval sent twice", __func__); 1808 exitval = buffer_get_int(&m); 1809 exitval_seen = 1; 1810 continue; 1811 default: 1812 e = buffer_get_string(&m, NULL); 1813 fatal("%s: master returned error: %s", __func__, e); 1814 } 1815 } 1816 1817 close(fd); 1818 if (rawmode) 1819 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1820 1821 if (muxclient_terminate) { 1822 debug2("Exiting on signal %d", muxclient_terminate); 1823 exitval = 255; 1824 } else if (!exitval_seen) { 1825 debug2("Control master terminated unexpectedly"); 1826 exitval = 255; 1827 } else 1828 debug2("Received exit status from master %d", exitval); 1829 1830 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1831 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1832 1833 exit(exitval); 1834 } 1835 1836 static int 1837 mux_client_request_stdio_fwd(int fd) 1838 { 1839 Buffer m; 1840 char *e; 1841 u_int type, rid, sid; 1842 int devnull; 1843 1844 debug3("%s: entering", __func__); 1845 1846 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1847 error("%s: master alive request failed", __func__); 1848 return -1; 1849 } 1850 1851 signal(SIGPIPE, SIG_IGN); 1852 1853 if (stdin_null_flag) { 1854 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1855 fatal("open(/dev/null): %s", strerror(errno)); 1856 if (dup2(devnull, STDIN_FILENO) == -1) 1857 fatal("dup2: %s", strerror(errno)); 1858 if (devnull > STDERR_FILENO) 1859 close(devnull); 1860 } 1861 1862 buffer_init(&m); 1863 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1864 buffer_put_int(&m, muxclient_request_id); 1865 buffer_put_cstring(&m, ""); /* reserved */ 1866 buffer_put_cstring(&m, stdio_forward_host); 1867 buffer_put_int(&m, stdio_forward_port); 1868 1869 if (mux_client_write_packet(fd, &m) != 0) 1870 fatal("%s: write packet: %s", __func__, strerror(errno)); 1871 1872 /* Send the stdio file descriptors */ 1873 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1874 mm_send_fd(fd, STDOUT_FILENO) == -1) 1875 fatal("%s: send fds failed", __func__); 1876 1877 debug3("%s: stdio forward request sent", __func__); 1878 1879 /* Read their reply */ 1880 buffer_clear(&m); 1881 1882 if (mux_client_read_packet(fd, &m) != 0) { 1883 error("%s: read from master failed: %s", 1884 __func__, strerror(errno)); 1885 buffer_free(&m); 1886 return -1; 1887 } 1888 1889 type = buffer_get_int(&m); 1890 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1891 fatal("%s: out of sequence reply: my id %u theirs %u", 1892 __func__, muxclient_request_id, rid); 1893 switch (type) { 1894 case MUX_S_SESSION_OPENED: 1895 sid = buffer_get_int(&m); 1896 debug("%s: master session id: %u", __func__, sid); 1897 break; 1898 case MUX_S_PERMISSION_DENIED: 1899 e = buffer_get_string(&m, NULL); 1900 buffer_free(&m); 1901 fatal("Master refused stdio forwarding request: %s", e); 1902 case MUX_S_FAILURE: 1903 e = buffer_get_string(&m, NULL); 1904 buffer_free(&m); 1905 fatal("%s: stdio forwarding request failed: %s", __func__, e); 1906 default: 1907 buffer_free(&m); 1908 error("%s: unexpected response from master 0x%08x", 1909 __func__, type); 1910 return -1; 1911 } 1912 muxclient_request_id++; 1913 1914 signal(SIGHUP, control_client_sighandler); 1915 signal(SIGINT, control_client_sighandler); 1916 signal(SIGTERM, control_client_sighandler); 1917 signal(SIGWINCH, control_client_sigrelay); 1918 1919 /* 1920 * Stick around until the controlee closes the client_fd. 1921 */ 1922 buffer_clear(&m); 1923 if (mux_client_read_packet(fd, &m) != 0) { 1924 if (errno == EPIPE || 1925 (errno == EINTR && muxclient_terminate != 0)) 1926 return 0; 1927 fatal("%s: mux_client_read_packet: %s", 1928 __func__, strerror(errno)); 1929 } 1930 fatal("%s: master returned unexpected message %u", __func__, type); 1931 } 1932 1933 static void 1934 mux_client_request_stop_listening(int fd) 1935 { 1936 Buffer m; 1937 char *e; 1938 u_int type, rid; 1939 1940 debug3("%s: entering", __func__); 1941 1942 buffer_init(&m); 1943 buffer_put_int(&m, MUX_C_STOP_LISTENING); 1944 buffer_put_int(&m, muxclient_request_id); 1945 1946 if (mux_client_write_packet(fd, &m) != 0) 1947 fatal("%s: write packet: %s", __func__, strerror(errno)); 1948 1949 buffer_clear(&m); 1950 1951 /* Read their reply */ 1952 if (mux_client_read_packet(fd, &m) != 0) 1953 fatal("%s: read from master failed: %s", 1954 __func__, strerror(errno)); 1955 1956 type = buffer_get_int(&m); 1957 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1958 fatal("%s: out of sequence reply: my id %u theirs %u", 1959 __func__, muxclient_request_id, rid); 1960 switch (type) { 1961 case MUX_S_OK: 1962 break; 1963 case MUX_S_PERMISSION_DENIED: 1964 e = buffer_get_string(&m, NULL); 1965 fatal("Master refused stop listening request: %s", e); 1966 case MUX_S_FAILURE: 1967 e = buffer_get_string(&m, NULL); 1968 fatal("%s: stop listening request failed: %s", __func__, e); 1969 default: 1970 fatal("%s: unexpected response from master 0x%08x", 1971 __func__, type); 1972 } 1973 buffer_free(&m); 1974 muxclient_request_id++; 1975 } 1976 1977 /* Multiplex client main loop. */ 1978 void 1979 muxclient(const char *path) 1980 { 1981 struct sockaddr_un addr; 1982 int sock; 1983 u_int pid; 1984 1985 if (muxclient_command == 0) { 1986 if (stdio_forward_host != NULL) 1987 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 1988 else 1989 muxclient_command = SSHMUX_COMMAND_OPEN; 1990 } 1991 1992 switch (options.control_master) { 1993 case SSHCTL_MASTER_AUTO: 1994 case SSHCTL_MASTER_AUTO_ASK: 1995 debug("auto-mux: Trying existing master"); 1996 /* FALLTHROUGH */ 1997 case SSHCTL_MASTER_NO: 1998 break; 1999 default: 2000 return; 2001 } 2002 2003 memset(&addr, '\0', sizeof(addr)); 2004 addr.sun_family = AF_UNIX; 2005 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 2006 strlen(path) + 1; 2007 2008 if (strlcpy(addr.sun_path, path, 2009 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2010 fatal("ControlPath too long"); 2011 2012 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2013 fatal("%s socket(): %s", __func__, strerror(errno)); 2014 2015 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 2016 switch (muxclient_command) { 2017 case SSHMUX_COMMAND_OPEN: 2018 case SSHMUX_COMMAND_STDIO_FWD: 2019 break; 2020 default: 2021 fatal("Control socket connect(%.100s): %s", path, 2022 strerror(errno)); 2023 } 2024 if (errno == ECONNREFUSED && 2025 options.control_master != SSHCTL_MASTER_NO) { 2026 debug("Stale control socket %.100s, unlinking", path); 2027 unlink(path); 2028 } else if (errno == ENOENT) { 2029 debug("Control socket \"%.100s\" does not exist", path); 2030 } else { 2031 error("Control socket connect(%.100s): %s", path, 2032 strerror(errno)); 2033 } 2034 close(sock); 2035 return; 2036 } 2037 set_nonblock(sock); 2038 2039 if (mux_client_hello_exchange(sock) != 0) { 2040 error("%s: master hello exchange failed", __func__); 2041 close(sock); 2042 return; 2043 } 2044 2045 switch (muxclient_command) { 2046 case SSHMUX_COMMAND_ALIVE_CHECK: 2047 if ((pid = mux_client_request_alive(sock)) == 0) 2048 fatal("%s: master alive check failed", __func__); 2049 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2050 exit(0); 2051 case SSHMUX_COMMAND_TERMINATE: 2052 mux_client_request_terminate(sock); 2053 fprintf(stderr, "Exit request sent.\r\n"); 2054 exit(0); 2055 case SSHMUX_COMMAND_FORWARD: 2056 if (mux_client_forwards(sock, 0) != 0) 2057 fatal("%s: master forward request failed", __func__); 2058 exit(0); 2059 case SSHMUX_COMMAND_OPEN: 2060 if (mux_client_forwards(sock, 0) != 0) { 2061 error("%s: master forward request failed", __func__); 2062 return; 2063 } 2064 mux_client_request_session(sock); 2065 return; 2066 case SSHMUX_COMMAND_STDIO_FWD: 2067 mux_client_request_stdio_fwd(sock); 2068 exit(0); 2069 case SSHMUX_COMMAND_STOP: 2070 mux_client_request_stop_listening(sock); 2071 fprintf(stderr, "Stop listening request sent.\r\n"); 2072 exit(0); 2073 case SSHMUX_COMMAND_CANCEL_FWD: 2074 if (mux_client_forwards(sock, 1) != 0) 2075 error("%s: master cancel forward request failed", 2076 __func__); 2077 exit(0); 2078 default: 2079 fatal("unrecognised muxclient_command %d", muxclient_command); 2080 } 2081 } 2082