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