1 /* $NetBSD: mux.c,v 1.16 2016/08/02 13:45:12 christos Exp $ */ 2 /* $OpenBSD: mux.c,v 1.60 2016/06/03 03:14:41 dtucker Exp $ */ 3 /* 4 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 /* ssh session multiplexing support */ 20 21 /* 22 * TODO: 23 * - Better signalling from master to slave, especially passing of 24 * error messages 25 * - Better fall-back from mux slave error to new connection. 26 * - ExitOnForwardingFailure 27 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 28 * - Support ~^Z in mux slaves. 29 * - Inspect or control sessions in master. 30 * - If we ever support the "signal" channel request, send signals on 31 * sessions in master. 32 */ 33 34 #include "includes.h" 35 __RCSID("$NetBSD: mux.c,v 1.16 2016/08/02 13:45:12 christos Exp $"); 36 #include <sys/types.h> 37 #include <sys/queue.h> 38 #include <sys/stat.h> 39 #include <sys/socket.h> 40 #include <sys/un.h> 41 42 #include <errno.h> 43 #include <fcntl.h> 44 #include <poll.h> 45 #include <signal.h> 46 #include <stdarg.h> 47 #include <stddef.h> 48 #include <stdlib.h> 49 #include <stdio.h> 50 #include <string.h> 51 #include <unistd.h> 52 #include <util.h> 53 #include <paths.h> 54 55 #include "atomicio.h" 56 #include "xmalloc.h" 57 #include "log.h" 58 #include "ssh.h" 59 #include "ssh2.h" 60 #include "pathnames.h" 61 #include "misc.h" 62 #include "match.h" 63 #include "buffer.h" 64 #include "channels.h" 65 #include "msg.h" 66 #include "packet.h" 67 #include "monitor_fdpass.h" 68 #include "sshpty.h" 69 #include "key.h" 70 #include "readconf.h" 71 #include "clientloop.h" 72 73 /* from ssh.c */ 74 extern int tty_flag; 75 extern Options options; 76 extern int stdin_null_flag; 77 extern char *host; 78 extern int subsystem_flag; 79 extern Buffer command; 80 extern volatile sig_atomic_t quit_pending; 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 stdio fwd open confirmation callback */ 96 struct mux_stdio_confirm_ctx { 97 u_int rid; 98 }; 99 100 /* Context for global channel callback */ 101 struct mux_channel_confirm_ctx { 102 u_int cid; /* channel id */ 103 u_int rid; /* request id */ 104 int fid; /* forward id */ 105 }; 106 107 /* fd to control socket */ 108 int muxserver_sock = -1; 109 110 /* client request id */ 111 u_int muxclient_request_id = 0; 112 113 /* Multiplexing control command */ 114 u_int muxclient_command = 0; 115 116 /* Set when signalled. */ 117 static volatile sig_atomic_t muxclient_terminate = 0; 118 119 /* PID of multiplex server */ 120 static u_int muxserver_pid = 0; 121 122 static Channel *mux_listener_channel = NULL; 123 124 struct mux_master_state { 125 int hello_rcvd; 126 }; 127 128 /* mux protocol messages */ 129 #define MUX_MSG_HELLO 0x00000001 130 #define MUX_C_NEW_SESSION 0x10000002 131 #define MUX_C_ALIVE_CHECK 0x10000004 132 #define MUX_C_TERMINATE 0x10000005 133 #define MUX_C_OPEN_FWD 0x10000006 134 #define MUX_C_CLOSE_FWD 0x10000007 135 #define MUX_C_NEW_STDIO_FWD 0x10000008 136 #define MUX_C_STOP_LISTENING 0x10000009 137 #define MUX_S_OK 0x80000001 138 #define MUX_S_PERMISSION_DENIED 0x80000002 139 #define MUX_S_FAILURE 0x80000003 140 #define MUX_S_EXIT_MESSAGE 0x80000004 141 #define MUX_S_ALIVE 0x80000005 142 #define MUX_S_SESSION_OPENED 0x80000006 143 #define MUX_S_REMOTE_PORT 0x80000007 144 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 145 146 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 147 #define MUX_FWD_LOCAL 1 148 #define MUX_FWD_REMOTE 2 149 #define MUX_FWD_DYNAMIC 3 150 151 static void mux_session_confirm(int, int, void *); 152 static void mux_stdio_confirm(int, int, void *); 153 154 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 155 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 156 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 157 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 158 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 159 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 160 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 161 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 162 163 static const struct { 164 u_int type; 165 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 166 } mux_master_handlers[] = { 167 { MUX_MSG_HELLO, process_mux_master_hello }, 168 { MUX_C_NEW_SESSION, process_mux_new_session }, 169 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 170 { MUX_C_TERMINATE, process_mux_terminate }, 171 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 172 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 173 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 174 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 175 { 0, NULL } 176 }; 177 178 /* Cleanup callback fired on closure of mux slave _session_ channel */ 179 /* ARGSUSED */ 180 static void 181 mux_master_session_cleanup_cb(int cid, void *unused) 182 { 183 Channel *cc, *c = channel_by_id(cid); 184 185 debug3("%s: entering for channel %d", __func__, cid); 186 if (c == NULL) 187 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 188 if (c->ctl_chan != -1) { 189 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 190 fatal("%s: channel %d missing control channel %d", 191 __func__, c->self, c->ctl_chan); 192 c->ctl_chan = -1; 193 cc->remote_id = -1; 194 chan_rcvd_oclose(cc); 195 } 196 channel_cancel_cleanup(c->self); 197 } 198 199 /* Cleanup callback fired on closure of mux slave _control_ channel */ 200 /* ARGSUSED */ 201 static void 202 mux_master_control_cleanup_cb(int cid, void *unused) 203 { 204 Channel *sc, *c = channel_by_id(cid); 205 206 debug3("%s: entering for channel %d", __func__, cid); 207 if (c == NULL) 208 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 209 if (c->remote_id != -1) { 210 if ((sc = channel_by_id(c->remote_id)) == NULL) 211 fatal("%s: channel %d missing session channel %d", 212 __func__, c->self, c->remote_id); 213 c->remote_id = -1; 214 sc->ctl_chan = -1; 215 if (sc->type != SSH_CHANNEL_OPEN && 216 sc->type != SSH_CHANNEL_OPENING) { 217 debug2("%s: channel %d: not open", __func__, sc->self); 218 chan_mark_dead(sc); 219 } else { 220 if (sc->istate == CHAN_INPUT_OPEN) 221 chan_read_failed(sc); 222 if (sc->ostate == CHAN_OUTPUT_OPEN) 223 chan_write_failed(sc); 224 } 225 } 226 channel_cancel_cleanup(c->self); 227 } 228 229 /* Check mux client environment variables before passing them to mux master. */ 230 static int 231 env_permitted(char *env) 232 { 233 int i, ret; 234 char name[1024], *cp; 235 236 if ((cp = strchr(env, '=')) == NULL || cp == env) 237 return 0; 238 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 239 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 240 error("env_permitted: name '%.100s...' too long", env); 241 return 0; 242 } 243 244 for (i = 0; i < options.num_send_env; i++) 245 if (match_pattern(name, options.send_env[i])) 246 return 1; 247 248 return 0; 249 } 250 251 /* Mux master protocol message handlers */ 252 253 static int 254 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 255 { 256 u_int ver; 257 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 258 259 if (state == NULL) 260 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 261 if (state->hello_rcvd) { 262 error("%s: HELLO received twice", __func__); 263 return -1; 264 } 265 if (buffer_get_int_ret(&ver, m) != 0) { 266 malf: 267 error("%s: malformed message", __func__); 268 return -1; 269 } 270 if (ver != SSHMUX_VER) { 271 error("Unsupported multiplexing protocol version %d " 272 "(expected %d)", ver, SSHMUX_VER); 273 return -1; 274 } 275 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 276 277 /* No extensions are presently defined */ 278 while (buffer_len(m) > 0) { 279 char *name = buffer_get_string_ret(m, NULL); 280 char *value = buffer_get_string_ret(m, NULL); 281 282 if (name == NULL || value == NULL) { 283 free(name); 284 free(value); 285 goto malf; 286 } 287 debug2("Unrecognised slave extension \"%s\"", name); 288 free(name); 289 free(value); 290 } 291 state->hello_rcvd = 1; 292 return 0; 293 } 294 295 static int 296 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 297 { 298 Channel *nc; 299 struct mux_session_confirm_ctx *cctx; 300 char *reserved, *cmd, *cp; 301 u_int i, j, len, env_len, escape_char, window, packetmax; 302 int new_fd[3]; 303 304 /* Reply for SSHMUX_COMMAND_OPEN */ 305 cctx = xcalloc(1, sizeof(*cctx)); 306 cctx->term = NULL; 307 cctx->rid = rid; 308 cmd = reserved = NULL; 309 cctx->env = NULL; 310 env_len = 0; 311 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 312 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 313 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 314 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 315 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 316 buffer_get_int_ret(&escape_char, m) != 0 || 317 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 318 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 319 malf: 320 free(cmd); 321 free(reserved); 322 for (j = 0; j < env_len; j++) 323 free(cctx->env[j]); 324 free(cctx->env); 325 free(cctx->term); 326 free(cctx); 327 error("%s: malformed message", __func__); 328 return -1; 329 } 330 free(reserved); 331 reserved = NULL; 332 333 while (buffer_len(m) > 0) { 334 #define MUX_MAX_ENV_VARS 4096 335 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 336 goto malf; 337 if (!env_permitted(cp)) { 338 free(cp); 339 continue; 340 } 341 cctx->env = xreallocarray(cctx->env, env_len + 2, 342 sizeof(*cctx->env)); 343 cctx->env[env_len++] = cp; 344 cctx->env[env_len] = NULL; 345 if (env_len > MUX_MAX_ENV_VARS) { 346 error(">%d environment variables received, ignoring " 347 "additional", MUX_MAX_ENV_VARS); 348 break; 349 } 350 } 351 352 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 353 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 354 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 355 cctx->want_subsys, cctx->term, cmd, env_len); 356 357 buffer_init(&cctx->cmd); 358 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 359 free(cmd); 360 cmd = NULL; 361 362 /* Gather fds from client */ 363 for(i = 0; i < 3; i++) { 364 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 365 error("%s: failed to receive fd %d from slave", 366 __func__, i); 367 for (j = 0; j < i; j++) 368 close(new_fd[j]); 369 for (j = 0; j < env_len; j++) 370 free(cctx->env[j]); 371 free(cctx->env); 372 free(cctx->term); 373 buffer_free(&cctx->cmd); 374 free(cctx); 375 376 /* prepare reply */ 377 buffer_put_int(r, MUX_S_FAILURE); 378 buffer_put_int(r, rid); 379 buffer_put_cstring(r, 380 "did not receive file descriptors"); 381 return -1; 382 } 383 } 384 385 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 386 new_fd[0], new_fd[1], new_fd[2]); 387 388 /* XXX support multiple child sessions in future */ 389 if (c->remote_id != -1) { 390 debug2("%s: session already open", __func__); 391 /* prepare reply */ 392 buffer_put_int(r, MUX_S_FAILURE); 393 buffer_put_int(r, rid); 394 buffer_put_cstring(r, "Multiple sessions not supported"); 395 cleanup: 396 close(new_fd[0]); 397 close(new_fd[1]); 398 close(new_fd[2]); 399 free(cctx->term); 400 if (env_len != 0) { 401 for (i = 0; i < env_len; i++) 402 free(cctx->env[i]); 403 free(cctx->env); 404 } 405 buffer_free(&cctx->cmd); 406 free(cctx); 407 return 0; 408 } 409 410 if (options.control_master == SSHCTL_MASTER_ASK || 411 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 412 if (!ask_permission("Allow shared connection to %s? ", host)) { 413 debug2("%s: session refused by user", __func__); 414 /* prepare reply */ 415 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 416 buffer_put_int(r, rid); 417 buffer_put_cstring(r, "Permission denied"); 418 goto cleanup; 419 } 420 } 421 422 /* Try to pick up ttymodes from client before it goes raw */ 423 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 424 error("%s: tcgetattr: %s", __func__, strerror(errno)); 425 426 /* enable nonblocking unless tty */ 427 if (!isatty(new_fd[0])) 428 set_nonblock(new_fd[0]); 429 if (!isatty(new_fd[1])) 430 set_nonblock(new_fd[1]); 431 if (!isatty(new_fd[2])) 432 set_nonblock(new_fd[2]); 433 434 window = CHAN_SES_WINDOW_DEFAULT; 435 packetmax = CHAN_SES_PACKET_DEFAULT; 436 if (cctx->want_tty) { 437 window >>= 1; 438 packetmax >>= 1; 439 } 440 441 nc = channel_new("session", SSH_CHANNEL_OPENING, 442 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 443 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 444 445 nc->ctl_chan = c->self; /* link session -> control channel */ 446 c->remote_id = nc->self; /* link control -> session channel */ 447 448 if (cctx->want_tty && escape_char != 0xffffffff) { 449 channel_register_filter(nc->self, 450 client_simple_escape_filter, NULL, 451 client_filter_cleanup, 452 client_new_escape_filter_ctx((int)escape_char)); 453 } 454 455 debug2("%s: channel_new: %d linked to control channel %d", 456 __func__, nc->self, nc->ctl_chan); 457 458 channel_send_open(nc->self); 459 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 460 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 461 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 462 463 /* reply is deferred, sent by mux_session_confirm */ 464 return 0; 465 } 466 467 static int 468 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 469 { 470 debug2("%s: channel %d: alive check", __func__, c->self); 471 472 /* prepare reply */ 473 buffer_put_int(r, MUX_S_ALIVE); 474 buffer_put_int(r, rid); 475 buffer_put_int(r, (u_int)getpid()); 476 477 return 0; 478 } 479 480 static int 481 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 482 { 483 debug2("%s: channel %d: terminate request", __func__, c->self); 484 485 if (options.control_master == SSHCTL_MASTER_ASK || 486 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 487 if (!ask_permission("Terminate shared connection to %s? ", 488 host)) { 489 debug2("%s: termination refused by user", __func__); 490 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 491 buffer_put_int(r, rid); 492 buffer_put_cstring(r, "Permission denied"); 493 return 0; 494 } 495 } 496 497 quit_pending = 1; 498 buffer_put_int(r, MUX_S_OK); 499 buffer_put_int(r, rid); 500 /* XXX exit happens too soon - message never makes it to client */ 501 return 0; 502 } 503 504 static char * 505 format_forward(u_int ftype, struct Forward *fwd) 506 { 507 char *ret; 508 509 switch (ftype) { 510 case MUX_FWD_LOCAL: 511 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 512 (fwd->listen_path != NULL) ? fwd->listen_path : 513 (fwd->listen_host == NULL) ? 514 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 515 fwd->listen_host, fwd->listen_port, 516 (fwd->connect_path != NULL) ? fwd->connect_path : 517 fwd->connect_host, fwd->connect_port); 518 break; 519 case MUX_FWD_DYNAMIC: 520 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 521 (fwd->listen_host == NULL) ? 522 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 523 fwd->listen_host, fwd->listen_port); 524 break; 525 case MUX_FWD_REMOTE: 526 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 527 (fwd->listen_path != NULL) ? fwd->listen_path : 528 (fwd->listen_host == NULL) ? 529 "LOCALHOST" : fwd->listen_host, 530 fwd->listen_port, 531 (fwd->connect_path != NULL) ? fwd->connect_path : 532 fwd->connect_host, fwd->connect_port); 533 break; 534 default: 535 fatal("%s: unknown forward type %u", __func__, ftype); 536 } 537 return ret; 538 } 539 540 static int 541 compare_host(const char *a, const char *b) 542 { 543 if (a == NULL && b == NULL) 544 return 1; 545 if (a == NULL || b == NULL) 546 return 0; 547 return strcmp(a, b) == 0; 548 } 549 550 static int 551 compare_forward(struct Forward *a, struct Forward *b) 552 { 553 if (!compare_host(a->listen_host, b->listen_host)) 554 return 0; 555 if (!compare_host(a->listen_path, b->listen_path)) 556 return 0; 557 if (a->listen_port != b->listen_port) 558 return 0; 559 if (!compare_host(a->connect_host, b->connect_host)) 560 return 0; 561 if (!compare_host(a->connect_path, b->connect_path)) 562 return 0; 563 if (a->connect_port != b->connect_port) 564 return 0; 565 566 return 1; 567 } 568 569 static void 570 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 571 { 572 struct mux_channel_confirm_ctx *fctx = ctxt; 573 char *failmsg = NULL; 574 struct Forward *rfwd; 575 Channel *c; 576 Buffer out; 577 578 if ((c = channel_by_id(fctx->cid)) == NULL) { 579 /* no channel for reply */ 580 error("%s: unknown channel", __func__); 581 return; 582 } 583 buffer_init(&out); 584 if (fctx->fid >= options.num_remote_forwards || 585 (options.remote_forwards[fctx->fid].connect_path == NULL && 586 options.remote_forwards[fctx->fid].connect_host == NULL)) { 587 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 588 goto fail; 589 } 590 rfwd = &options.remote_forwards[fctx->fid]; 591 debug("%s: %s for: listen %d, connect %s:%d", __func__, 592 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 593 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 594 rfwd->connect_host, rfwd->connect_port); 595 if (type == SSH2_MSG_REQUEST_SUCCESS) { 596 if (rfwd->listen_port == 0) { 597 rfwd->allocated_port = packet_get_int(); 598 debug("Allocated port %u for mux remote forward" 599 " to %s:%d", rfwd->allocated_port, 600 rfwd->connect_host, rfwd->connect_port); 601 buffer_put_int(&out, MUX_S_REMOTE_PORT); 602 buffer_put_int(&out, fctx->rid); 603 buffer_put_int(&out, rfwd->allocated_port); 604 channel_update_permitted_opens(rfwd->handle, 605 rfwd->allocated_port); 606 } else { 607 buffer_put_int(&out, MUX_S_OK); 608 buffer_put_int(&out, fctx->rid); 609 } 610 goto out; 611 } else { 612 if (rfwd->listen_port == 0) 613 channel_update_permitted_opens(rfwd->handle, -1); 614 if (rfwd->listen_path != NULL) 615 xasprintf(&failmsg, "remote port forwarding failed for " 616 "listen path %s", rfwd->listen_path); 617 else 618 xasprintf(&failmsg, "remote port forwarding failed for " 619 "listen port %d", rfwd->listen_port); 620 621 debug2("%s: clearing registered forwarding for listen %d, " 622 "connect %s:%d", __func__, rfwd->listen_port, 623 rfwd->connect_path ? rfwd->connect_path : 624 rfwd->connect_host, rfwd->connect_port); 625 626 free(rfwd->listen_host); 627 free(rfwd->listen_path); 628 free(rfwd->connect_host); 629 free(rfwd->connect_path); 630 memset(rfwd, 0, sizeof(*rfwd)); 631 } 632 fail: 633 error("%s: %s", __func__, failmsg); 634 buffer_put_int(&out, MUX_S_FAILURE); 635 buffer_put_int(&out, fctx->rid); 636 buffer_put_cstring(&out, failmsg); 637 free(failmsg); 638 out: 639 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 640 buffer_free(&out); 641 if (c->mux_pause <= 0) 642 fatal("%s: mux_pause %d", __func__, c->mux_pause); 643 c->mux_pause = 0; /* start processing messages again */ 644 } 645 646 static int 647 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 648 { 649 struct Forward fwd; 650 char *fwd_desc = NULL; 651 char *listen_addr, *connect_addr; 652 u_int ftype; 653 u_int lport, cport; 654 int i, ret = 0, freefwd = 1; 655 656 memset(&fwd, 0, sizeof(fwd)); 657 658 /* XXX - lport/cport check redundant */ 659 if (buffer_get_int_ret(&ftype, m) != 0 || 660 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 661 buffer_get_int_ret(&lport, m) != 0 || 662 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 663 buffer_get_int_ret(&cport, m) != 0 || 664 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 665 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 666 error("%s: malformed message", __func__); 667 ret = -1; 668 goto out; 669 } 670 if (*listen_addr == '\0') { 671 free(listen_addr); 672 listen_addr = NULL; 673 } 674 if (*connect_addr == '\0') { 675 free(connect_addr); 676 connect_addr = NULL; 677 } 678 679 memset(&fwd, 0, sizeof(fwd)); 680 fwd.listen_port = lport; 681 if (fwd.listen_port == PORT_STREAMLOCAL) 682 fwd.listen_path = listen_addr; 683 else 684 fwd.listen_host = listen_addr; 685 fwd.connect_port = cport; 686 if (fwd.connect_port == PORT_STREAMLOCAL) 687 fwd.connect_path = connect_addr; 688 else 689 fwd.connect_host = connect_addr; 690 691 debug2("%s: channel %d: request %s", __func__, c->self, 692 (fwd_desc = format_forward(ftype, &fwd))); 693 694 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 695 ftype != MUX_FWD_DYNAMIC) { 696 logit("%s: invalid forwarding type %u", __func__, ftype); 697 invalid: 698 free(listen_addr); 699 free(connect_addr); 700 buffer_put_int(r, MUX_S_FAILURE); 701 buffer_put_int(r, rid); 702 buffer_put_cstring(r, "Invalid forwarding request"); 703 return 0; 704 } 705 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 706 logit("%s: streamlocal and dynamic forwards " 707 "are mutually exclusive", __func__); 708 goto invalid; 709 } 710 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 711 logit("%s: invalid listen port %u", __func__, 712 fwd.listen_port); 713 goto invalid; 714 } 715 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 716 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 717 logit("%s: invalid connect port %u", __func__, 718 fwd.connect_port); 719 goto invalid; 720 } 721 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 722 logit("%s: missing connect host", __func__); 723 goto invalid; 724 } 725 726 /* Skip forwards that have already been requested */ 727 switch (ftype) { 728 case MUX_FWD_LOCAL: 729 case MUX_FWD_DYNAMIC: 730 for (i = 0; i < options.num_local_forwards; i++) { 731 if (compare_forward(&fwd, 732 options.local_forwards + i)) { 733 exists: 734 debug2("%s: found existing forwarding", 735 __func__); 736 buffer_put_int(r, MUX_S_OK); 737 buffer_put_int(r, rid); 738 goto out; 739 } 740 } 741 break; 742 case MUX_FWD_REMOTE: 743 for (i = 0; i < options.num_remote_forwards; i++) { 744 if (compare_forward(&fwd, 745 options.remote_forwards + i)) { 746 if (fwd.listen_port != 0) 747 goto exists; 748 debug2("%s: found allocated port", 749 __func__); 750 buffer_put_int(r, MUX_S_REMOTE_PORT); 751 buffer_put_int(r, rid); 752 buffer_put_int(r, 753 options.remote_forwards[i].allocated_port); 754 goto out; 755 } 756 } 757 break; 758 } 759 760 if (options.control_master == SSHCTL_MASTER_ASK || 761 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 762 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 763 debug2("%s: forwarding refused by user", __func__); 764 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 765 buffer_put_int(r, rid); 766 buffer_put_cstring(r, "Permission denied"); 767 goto out; 768 } 769 } 770 771 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 772 if (!channel_setup_local_fwd_listener(&fwd, 773 &options.fwd_opts)) { 774 fail: 775 logit("slave-requested %s failed", fwd_desc); 776 buffer_put_int(r, MUX_S_FAILURE); 777 buffer_put_int(r, rid); 778 buffer_put_cstring(r, "Port forwarding failed"); 779 goto out; 780 } 781 add_local_forward(&options, &fwd); 782 freefwd = 0; 783 } else { 784 struct mux_channel_confirm_ctx *fctx; 785 786 fwd.handle = channel_request_remote_forwarding(&fwd); 787 if (fwd.handle < 0) 788 goto fail; 789 add_remote_forward(&options, &fwd); 790 fctx = xcalloc(1, sizeof(*fctx)); 791 fctx->cid = c->self; 792 fctx->rid = rid; 793 fctx->fid = options.num_remote_forwards - 1; 794 client_register_global_confirm(mux_confirm_remote_forward, 795 fctx); 796 freefwd = 0; 797 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 798 /* delayed reply in mux_confirm_remote_forward */ 799 goto out; 800 } 801 buffer_put_int(r, MUX_S_OK); 802 buffer_put_int(r, rid); 803 out: 804 free(fwd_desc); 805 if (freefwd) { 806 free(fwd.listen_host); 807 free(fwd.listen_path); 808 free(fwd.connect_host); 809 free(fwd.connect_path); 810 } 811 return ret; 812 } 813 814 static int 815 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 816 { 817 struct Forward fwd, *found_fwd; 818 char *fwd_desc = NULL; 819 const char *error_reason = NULL; 820 char *listen_addr = NULL, *connect_addr = NULL; 821 u_int ftype; 822 int i, ret = 0; 823 u_int lport, cport; 824 825 memset(&fwd, 0, sizeof(fwd)); 826 827 if (buffer_get_int_ret(&ftype, m) != 0 || 828 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 829 buffer_get_int_ret(&lport, m) != 0 || 830 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 831 buffer_get_int_ret(&cport, m) != 0 || 832 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 833 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 834 error("%s: malformed message", __func__); 835 ret = -1; 836 goto out; 837 } 838 839 if (*listen_addr == '\0') { 840 free(listen_addr); 841 listen_addr = NULL; 842 } 843 if (*connect_addr == '\0') { 844 free(connect_addr); 845 connect_addr = NULL; 846 } 847 848 memset(&fwd, 0, sizeof(fwd)); 849 fwd.listen_port = lport; 850 if (fwd.listen_port == PORT_STREAMLOCAL) 851 fwd.listen_path = listen_addr; 852 else 853 fwd.listen_host = listen_addr; 854 fwd.connect_port = cport; 855 if (fwd.connect_port == PORT_STREAMLOCAL) 856 fwd.connect_path = connect_addr; 857 else 858 fwd.connect_host = connect_addr; 859 860 debug2("%s: channel %d: request cancel %s", __func__, c->self, 861 (fwd_desc = format_forward(ftype, &fwd))); 862 863 /* make sure this has been requested */ 864 found_fwd = NULL; 865 switch (ftype) { 866 case MUX_FWD_LOCAL: 867 case MUX_FWD_DYNAMIC: 868 for (i = 0; i < options.num_local_forwards; i++) { 869 if (compare_forward(&fwd, 870 options.local_forwards + i)) { 871 found_fwd = options.local_forwards + i; 872 break; 873 } 874 } 875 break; 876 case MUX_FWD_REMOTE: 877 for (i = 0; i < options.num_remote_forwards; i++) { 878 if (compare_forward(&fwd, 879 options.remote_forwards + i)) { 880 found_fwd = options.remote_forwards + i; 881 break; 882 } 883 } 884 break; 885 } 886 887 if (found_fwd == NULL) 888 error_reason = "port not forwarded"; 889 else if (ftype == MUX_FWD_REMOTE) { 890 /* 891 * This shouldn't fail unless we confused the host/port 892 * between options.remote_forwards and permitted_opens. 893 * However, for dynamic allocated listen ports we need 894 * to use the actual listen port. 895 */ 896 if (channel_request_rforward_cancel(found_fwd) == -1) 897 error_reason = "port not in permitted opens"; 898 } else { /* local and dynamic forwards */ 899 /* Ditto */ 900 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 901 &options.fwd_opts) == -1) 902 error_reason = "port not found"; 903 } 904 905 if (error_reason == NULL) { 906 buffer_put_int(r, MUX_S_OK); 907 buffer_put_int(r, rid); 908 909 free(found_fwd->listen_host); 910 free(found_fwd->listen_path); 911 free(found_fwd->connect_host); 912 free(found_fwd->connect_path); 913 found_fwd->listen_host = found_fwd->connect_host = NULL; 914 found_fwd->listen_path = found_fwd->connect_path = NULL; 915 found_fwd->listen_port = found_fwd->connect_port = 0; 916 } else { 917 buffer_put_int(r, MUX_S_FAILURE); 918 buffer_put_int(r, rid); 919 buffer_put_cstring(r, error_reason); 920 } 921 out: 922 free(fwd_desc); 923 free(listen_addr); 924 free(connect_addr); 925 926 return ret; 927 } 928 929 static int 930 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 931 { 932 Channel *nc; 933 char *reserved, *chost; 934 u_int cport, i, j; 935 int new_fd[2]; 936 struct mux_stdio_confirm_ctx *cctx; 937 938 chost = reserved = NULL; 939 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 940 (chost = buffer_get_string_ret(m, NULL)) == NULL || 941 buffer_get_int_ret(&cport, m) != 0) { 942 free(reserved); 943 free(chost); 944 error("%s: malformed message", __func__); 945 return -1; 946 } 947 free(reserved); 948 949 debug2("%s: channel %d: request stdio fwd to %s:%u", 950 __func__, c->self, chost, cport); 951 952 /* Gather fds from client */ 953 for(i = 0; i < 2; i++) { 954 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 955 error("%s: failed to receive fd %d from slave", 956 __func__, i); 957 for (j = 0; j < i; j++) 958 close(new_fd[j]); 959 free(chost); 960 961 /* prepare reply */ 962 buffer_put_int(r, MUX_S_FAILURE); 963 buffer_put_int(r, rid); 964 buffer_put_cstring(r, 965 "did not receive file descriptors"); 966 return -1; 967 } 968 } 969 970 debug3("%s: got fds stdin %d, stdout %d", __func__, 971 new_fd[0], new_fd[1]); 972 973 /* XXX support multiple child sessions in future */ 974 if (c->remote_id != -1) { 975 debug2("%s: session already open", __func__); 976 /* prepare reply */ 977 buffer_put_int(r, MUX_S_FAILURE); 978 buffer_put_int(r, rid); 979 buffer_put_cstring(r, "Multiple sessions not supported"); 980 cleanup: 981 close(new_fd[0]); 982 close(new_fd[1]); 983 free(chost); 984 return 0; 985 } 986 987 if (options.control_master == SSHCTL_MASTER_ASK || 988 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 989 if (!ask_permission("Allow forward to %s:%u? ", 990 chost, cport)) { 991 debug2("%s: stdio fwd refused by user", __func__); 992 /* prepare reply */ 993 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 994 buffer_put_int(r, rid); 995 buffer_put_cstring(r, "Permission denied"); 996 goto cleanup; 997 } 998 } 999 1000 /* enable nonblocking unless tty */ 1001 if (!isatty(new_fd[0])) 1002 set_nonblock(new_fd[0]); 1003 if (!isatty(new_fd[1])) 1004 set_nonblock(new_fd[1]); 1005 1006 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1007 1008 nc->ctl_chan = c->self; /* link session -> control channel */ 1009 c->remote_id = nc->self; /* link control -> session channel */ 1010 1011 debug2("%s: channel_new: %d linked to control channel %d", 1012 __func__, nc->self, nc->ctl_chan); 1013 1014 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1015 1016 cctx = xcalloc(1, sizeof(*cctx)); 1017 cctx->rid = rid; 1018 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1019 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1020 1021 /* reply is deferred, sent by mux_session_confirm */ 1022 return 0; 1023 } 1024 1025 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1026 static void 1027 mux_stdio_confirm(int id, int success, void *arg) 1028 { 1029 struct mux_stdio_confirm_ctx *cctx = arg; 1030 Channel *c, *cc; 1031 Buffer reply; 1032 1033 if (cctx == NULL) 1034 fatal("%s: cctx == NULL", __func__); 1035 if ((c = channel_by_id(id)) == NULL) 1036 fatal("%s: no channel for id %d", __func__, id); 1037 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1038 fatal("%s: channel %d lacks control channel %d", __func__, 1039 id, c->ctl_chan); 1040 1041 if (!success) { 1042 debug3("%s: sending failure reply", __func__); 1043 /* prepare reply */ 1044 buffer_init(&reply); 1045 buffer_put_int(&reply, MUX_S_FAILURE); 1046 buffer_put_int(&reply, cctx->rid); 1047 buffer_put_cstring(&reply, "Session open refused by peer"); 1048 goto done; 1049 } 1050 1051 debug3("%s: sending success reply", __func__); 1052 /* prepare reply */ 1053 buffer_init(&reply); 1054 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1055 buffer_put_int(&reply, cctx->rid); 1056 buffer_put_int(&reply, c->self); 1057 1058 done: 1059 /* Send reply */ 1060 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1061 buffer_free(&reply); 1062 1063 if (cc->mux_pause <= 0) 1064 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1065 cc->mux_pause = 0; /* start processing messages again */ 1066 c->open_confirm_ctx = NULL; 1067 free(cctx); 1068 } 1069 1070 static int 1071 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1072 { 1073 debug("%s: channel %d: stop listening", __func__, c->self); 1074 1075 if (options.control_master == SSHCTL_MASTER_ASK || 1076 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1077 if (!ask_permission("Disable further multiplexing on shared " 1078 "connection to %s? ", host)) { 1079 debug2("%s: stop listen refused by user", __func__); 1080 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1081 buffer_put_int(r, rid); 1082 buffer_put_cstring(r, "Permission denied"); 1083 return 0; 1084 } 1085 } 1086 1087 if (mux_listener_channel != NULL) { 1088 channel_free(mux_listener_channel); 1089 client_stop_mux(); 1090 free(options.control_path); 1091 options.control_path = NULL; 1092 mux_listener_channel = NULL; 1093 muxserver_sock = -1; 1094 } 1095 1096 /* prepare reply */ 1097 buffer_put_int(r, MUX_S_OK); 1098 buffer_put_int(r, rid); 1099 1100 return 0; 1101 } 1102 1103 /* Channel callbacks fired on read/write from mux slave fd */ 1104 static int 1105 mux_master_read_cb(Channel *c) 1106 { 1107 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1108 Buffer in, out; 1109 const u_char *ptr; 1110 u_int type, rid, have, i; 1111 int ret = -1; 1112 1113 /* Setup ctx and */ 1114 if (c->mux_ctx == NULL) { 1115 state = xcalloc(1, sizeof(*state)); 1116 c->mux_ctx = state; 1117 channel_register_cleanup(c->self, 1118 mux_master_control_cleanup_cb, 0); 1119 1120 /* Send hello */ 1121 buffer_init(&out); 1122 buffer_put_int(&out, MUX_MSG_HELLO); 1123 buffer_put_int(&out, SSHMUX_VER); 1124 /* no extensions */ 1125 buffer_put_string(&c->output, buffer_ptr(&out), 1126 buffer_len(&out)); 1127 buffer_free(&out); 1128 debug3("%s: channel %d: hello sent", __func__, c->self); 1129 return 0; 1130 } 1131 1132 buffer_init(&in); 1133 buffer_init(&out); 1134 1135 /* Channel code ensures that we receive whole packets */ 1136 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1137 malf: 1138 error("%s: malformed message", __func__); 1139 goto out; 1140 } 1141 buffer_append(&in, ptr, have); 1142 1143 if (buffer_get_int_ret(&type, &in) != 0) 1144 goto malf; 1145 debug3("%s: channel %d packet type 0x%08x len %u", 1146 __func__, c->self, type, buffer_len(&in)); 1147 1148 if (type == MUX_MSG_HELLO) 1149 rid = 0; 1150 else { 1151 if (!state->hello_rcvd) { 1152 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1153 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1154 goto out; 1155 } 1156 if (buffer_get_int_ret(&rid, &in) != 0) 1157 goto malf; 1158 } 1159 1160 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1161 if (type == mux_master_handlers[i].type) { 1162 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1163 break; 1164 } 1165 } 1166 if (mux_master_handlers[i].handler == NULL) { 1167 error("%s: unsupported mux message 0x%08x", __func__, type); 1168 buffer_put_int(&out, MUX_S_FAILURE); 1169 buffer_put_int(&out, rid); 1170 buffer_put_cstring(&out, "unsupported request"); 1171 ret = 0; 1172 } 1173 /* Enqueue reply packet */ 1174 if (buffer_len(&out) != 0) { 1175 buffer_put_string(&c->output, buffer_ptr(&out), 1176 buffer_len(&out)); 1177 } 1178 out: 1179 buffer_free(&in); 1180 buffer_free(&out); 1181 return ret; 1182 } 1183 1184 void 1185 mux_exit_message(Channel *c, int exitval) 1186 { 1187 Buffer m; 1188 Channel *mux_chan; 1189 1190 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1191 exitval); 1192 1193 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1194 fatal("%s: channel %d missing mux channel %d", 1195 __func__, c->self, c->ctl_chan); 1196 1197 /* Append exit message packet to control socket output queue */ 1198 buffer_init(&m); 1199 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1200 buffer_put_int(&m, c->self); 1201 buffer_put_int(&m, exitval); 1202 1203 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1204 buffer_free(&m); 1205 } 1206 1207 void 1208 mux_tty_alloc_failed(Channel *c) 1209 { 1210 Buffer m; 1211 Channel *mux_chan; 1212 1213 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1214 1215 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1216 fatal("%s: channel %d missing mux channel %d", 1217 __func__, c->self, c->ctl_chan); 1218 1219 /* Append exit message packet to control socket output queue */ 1220 buffer_init(&m); 1221 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1222 buffer_put_int(&m, c->self); 1223 1224 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1225 buffer_free(&m); 1226 } 1227 1228 /* Prepare a mux master to listen on a Unix domain socket. */ 1229 void 1230 muxserver_listen(void) 1231 { 1232 mode_t old_umask; 1233 char *orig_control_path = options.control_path; 1234 char rbuf[16+1]; 1235 u_int i, r; 1236 int oerrno; 1237 1238 if (options.control_path == NULL || 1239 options.control_master == SSHCTL_MASTER_NO) 1240 return; 1241 1242 debug("setting up multiplex master socket"); 1243 1244 /* 1245 * Use a temporary path before listen so we can pseudo-atomically 1246 * establish the listening socket in its final location to avoid 1247 * other processes racing in between bind() and listen() and hitting 1248 * an unready socket. 1249 */ 1250 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1251 r = arc4random_uniform(26+26+10); 1252 rbuf[i] = (r < 26) ? 'a' + r : 1253 (r < 26*2) ? 'A' + r - 26 : 1254 '0' + r - 26 - 26; 1255 } 1256 rbuf[sizeof(rbuf) - 1] = '\0'; 1257 options.control_path = NULL; 1258 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1259 debug3("%s: temporary control path %s", __func__, options.control_path); 1260 1261 old_umask = umask(0177); 1262 muxserver_sock = unix_listener(options.control_path, 64, 0); 1263 oerrno = errno; 1264 umask(old_umask); 1265 if (muxserver_sock < 0) { 1266 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1267 error("ControlSocket %s already exists, " 1268 "disabling multiplexing", options.control_path); 1269 disable_mux_master: 1270 if (muxserver_sock != -1) { 1271 close(muxserver_sock); 1272 muxserver_sock = -1; 1273 } 1274 free(orig_control_path); 1275 free(options.control_path); 1276 options.control_path = NULL; 1277 options.control_master = SSHCTL_MASTER_NO; 1278 return; 1279 } else { 1280 /* unix_listener() logs the error */ 1281 cleanup_exit(255); 1282 } 1283 } 1284 1285 /* Now atomically "move" the mux socket into position */ 1286 if (link(options.control_path, orig_control_path) != 0) { 1287 if (errno != EEXIST) { 1288 fatal("%s: link mux listener %s => %s: %s", __func__, 1289 options.control_path, orig_control_path, 1290 strerror(errno)); 1291 } 1292 error("ControlSocket %s already exists, disabling multiplexing", 1293 orig_control_path); 1294 unlink(options.control_path); 1295 goto disable_mux_master; 1296 } 1297 unlink(options.control_path); 1298 free(options.control_path); 1299 options.control_path = orig_control_path; 1300 1301 set_nonblock(muxserver_sock); 1302 1303 mux_listener_channel = channel_new("mux listener", 1304 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1305 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1306 0, options.control_path, 1); 1307 mux_listener_channel->mux_rcb = mux_master_read_cb; 1308 debug3("%s: mux listener channel %d fd %d", __func__, 1309 mux_listener_channel->self, mux_listener_channel->sock); 1310 } 1311 1312 /* Callback on open confirmation in mux master for a mux client session. */ 1313 static void 1314 mux_session_confirm(int id, int success, void *arg) 1315 { 1316 struct mux_session_confirm_ctx *cctx = arg; 1317 const char *display; 1318 Channel *c, *cc; 1319 int i; 1320 Buffer reply; 1321 1322 if (cctx == NULL) 1323 fatal("%s: cctx == NULL", __func__); 1324 if ((c = channel_by_id(id)) == NULL) 1325 fatal("%s: no channel for id %d", __func__, id); 1326 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1327 fatal("%s: channel %d lacks control channel %d", __func__, 1328 id, c->ctl_chan); 1329 1330 if (!success) { 1331 debug3("%s: sending failure reply", __func__); 1332 /* prepare reply */ 1333 buffer_init(&reply); 1334 buffer_put_int(&reply, MUX_S_FAILURE); 1335 buffer_put_int(&reply, cctx->rid); 1336 buffer_put_cstring(&reply, "Session open refused by peer"); 1337 goto done; 1338 } 1339 1340 display = getenv("DISPLAY"); 1341 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1342 char *proto, *data; 1343 1344 /* Get reasonable local authentication information. */ 1345 if (client_x11_get_proto(display, options.xauth_location, 1346 options.forward_x11_trusted, options.forward_x11_timeout, 1347 &proto, &data) == 0) { 1348 /* Request forwarding with authentication spoofing. */ 1349 debug("Requesting X11 forwarding with authentication " 1350 "spoofing."); 1351 x11_request_forwarding_with_spoofing(id, display, proto, 1352 data, 1); 1353 /* XXX exit_on_forward_failure */ 1354 client_expect_confirm(id, "X11 forwarding", 1355 CONFIRM_WARN); 1356 } 1357 } 1358 1359 if (cctx->want_agent_fwd && options.forward_agent) { 1360 debug("Requesting authentication agent forwarding."); 1361 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1362 packet_send(); 1363 } 1364 1365 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1366 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1367 1368 debug3("%s: sending success reply", __func__); 1369 /* prepare reply */ 1370 buffer_init(&reply); 1371 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1372 buffer_put_int(&reply, cctx->rid); 1373 buffer_put_int(&reply, c->self); 1374 1375 done: 1376 /* Send reply */ 1377 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1378 buffer_free(&reply); 1379 1380 if (cc->mux_pause <= 0) 1381 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1382 cc->mux_pause = 0; /* start processing messages again */ 1383 c->open_confirm_ctx = NULL; 1384 buffer_free(&cctx->cmd); 1385 free(cctx->term); 1386 if (cctx->env != NULL) { 1387 for (i = 0; cctx->env[i] != NULL; i++) 1388 free(cctx->env[i]); 1389 free(cctx->env); 1390 } 1391 free(cctx); 1392 } 1393 1394 /* ** Multiplexing client support */ 1395 1396 /* Exit signal handler */ 1397 static void 1398 control_client_sighandler(int signo) 1399 { 1400 muxclient_terminate = signo; 1401 } 1402 1403 /* 1404 * Relay signal handler - used to pass some signals from mux client to 1405 * mux master. 1406 */ 1407 static void 1408 control_client_sigrelay(int signo) 1409 { 1410 int save_errno = errno; 1411 1412 if (muxserver_pid > 1) 1413 kill(muxserver_pid, signo); 1414 1415 errno = save_errno; 1416 } 1417 1418 static int 1419 mux_client_read(int fd, Buffer *b, u_int need) 1420 { 1421 u_int have; 1422 ssize_t len; 1423 u_char *p; 1424 struct pollfd pfd; 1425 1426 pfd.fd = fd; 1427 pfd.events = POLLIN; 1428 p = buffer_append_space(b, need); 1429 for (have = 0; have < need; ) { 1430 if (muxclient_terminate) { 1431 errno = EINTR; 1432 return -1; 1433 } 1434 len = read(fd, p + have, need - have); 1435 if (len < 0) { 1436 switch (errno) { 1437 case EAGAIN: 1438 (void)poll(&pfd, 1, -1); 1439 /* FALLTHROUGH */ 1440 case EINTR: 1441 continue; 1442 default: 1443 return -1; 1444 } 1445 } 1446 if (len == 0) { 1447 errno = EPIPE; 1448 return -1; 1449 } 1450 have += (u_int)len; 1451 } 1452 return 0; 1453 } 1454 1455 static int 1456 mux_client_write_packet(int fd, Buffer *m) 1457 { 1458 Buffer queue; 1459 u_int have, need; 1460 int oerrno, len; 1461 u_char *ptr; 1462 struct pollfd pfd; 1463 1464 pfd.fd = fd; 1465 pfd.events = POLLOUT; 1466 buffer_init(&queue); 1467 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1468 1469 need = buffer_len(&queue); 1470 ptr = buffer_ptr(&queue); 1471 1472 for (have = 0; have < need; ) { 1473 if (muxclient_terminate) { 1474 buffer_free(&queue); 1475 errno = EINTR; 1476 return -1; 1477 } 1478 len = write(fd, ptr + have, need - have); 1479 if (len < 0) { 1480 switch (errno) { 1481 case EAGAIN: 1482 (void)poll(&pfd, 1, -1); 1483 /* FALLTHROUGH */ 1484 case EINTR: 1485 continue; 1486 default: 1487 oerrno = errno; 1488 buffer_free(&queue); 1489 errno = oerrno; 1490 return -1; 1491 } 1492 } 1493 if (len == 0) { 1494 buffer_free(&queue); 1495 errno = EPIPE; 1496 return -1; 1497 } 1498 have += (u_int)len; 1499 } 1500 buffer_free(&queue); 1501 return 0; 1502 } 1503 1504 static int 1505 mux_client_read_packet(int fd, Buffer *m) 1506 { 1507 Buffer queue; 1508 u_int need, have; 1509 const u_char *ptr; 1510 int oerrno; 1511 1512 buffer_init(&queue); 1513 if (mux_client_read(fd, &queue, 4) != 0) { 1514 if ((oerrno = errno) == EPIPE) 1515 debug3("%s: read header failed: %s", __func__, 1516 strerror(errno)); 1517 buffer_free(&queue); 1518 errno = oerrno; 1519 return -1; 1520 } 1521 need = get_u32(buffer_ptr(&queue)); 1522 if (mux_client_read(fd, &queue, need) != 0) { 1523 oerrno = errno; 1524 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1525 buffer_free(&queue); 1526 errno = oerrno; 1527 return -1; 1528 } 1529 ptr = buffer_get_string_ptr(&queue, &have); 1530 buffer_append(m, ptr, have); 1531 buffer_free(&queue); 1532 return 0; 1533 } 1534 1535 static int 1536 mux_client_hello_exchange(int fd) 1537 { 1538 Buffer m; 1539 u_int type, ver; 1540 1541 buffer_init(&m); 1542 buffer_put_int(&m, MUX_MSG_HELLO); 1543 buffer_put_int(&m, SSHMUX_VER); 1544 /* no extensions */ 1545 1546 if (mux_client_write_packet(fd, &m) != 0) 1547 fatal("%s: write packet: %s", __func__, strerror(errno)); 1548 1549 buffer_clear(&m); 1550 1551 /* Read their HELLO */ 1552 if (mux_client_read_packet(fd, &m) != 0) { 1553 buffer_free(&m); 1554 return -1; 1555 } 1556 1557 type = buffer_get_int(&m); 1558 if (type != MUX_MSG_HELLO) 1559 fatal("%s: expected HELLO (%u) received %u", 1560 __func__, MUX_MSG_HELLO, type); 1561 ver = buffer_get_int(&m); 1562 if (ver != SSHMUX_VER) 1563 fatal("Unsupported multiplexing protocol version %d " 1564 "(expected %d)", ver, SSHMUX_VER); 1565 debug2("%s: master version %u", __func__, ver); 1566 /* No extensions are presently defined */ 1567 while (buffer_len(&m) > 0) { 1568 char *name = buffer_get_string(&m, NULL); 1569 char *value = buffer_get_string(&m, NULL); 1570 1571 debug2("Unrecognised master extension \"%s\"", name); 1572 free(name); 1573 free(value); 1574 } 1575 buffer_free(&m); 1576 return 0; 1577 } 1578 1579 static u_int 1580 mux_client_request_alive(int fd) 1581 { 1582 Buffer m; 1583 char *e; 1584 u_int pid, type, rid; 1585 1586 debug3("%s: entering", __func__); 1587 1588 buffer_init(&m); 1589 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1590 buffer_put_int(&m, muxclient_request_id); 1591 1592 if (mux_client_write_packet(fd, &m) != 0) 1593 fatal("%s: write packet: %s", __func__, strerror(errno)); 1594 1595 buffer_clear(&m); 1596 1597 /* Read their reply */ 1598 if (mux_client_read_packet(fd, &m) != 0) { 1599 buffer_free(&m); 1600 return 0; 1601 } 1602 1603 type = buffer_get_int(&m); 1604 if (type != MUX_S_ALIVE) { 1605 e = buffer_get_string(&m, NULL); 1606 fatal("%s: master returned error: %s", __func__, e); 1607 } 1608 1609 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1610 fatal("%s: out of sequence reply: my id %u theirs %u", 1611 __func__, muxclient_request_id, rid); 1612 pid = buffer_get_int(&m); 1613 buffer_free(&m); 1614 1615 debug3("%s: done pid = %u", __func__, pid); 1616 1617 muxclient_request_id++; 1618 1619 return pid; 1620 } 1621 1622 static void 1623 mux_client_request_terminate(int fd) 1624 { 1625 Buffer m; 1626 char *e; 1627 u_int type, rid; 1628 1629 debug3("%s: entering", __func__); 1630 1631 buffer_init(&m); 1632 buffer_put_int(&m, MUX_C_TERMINATE); 1633 buffer_put_int(&m, muxclient_request_id); 1634 1635 if (mux_client_write_packet(fd, &m) != 0) 1636 fatal("%s: write packet: %s", __func__, strerror(errno)); 1637 1638 buffer_clear(&m); 1639 1640 /* Read their reply */ 1641 if (mux_client_read_packet(fd, &m) != 0) { 1642 /* Remote end exited already */ 1643 if (errno == EPIPE) { 1644 buffer_free(&m); 1645 return; 1646 } 1647 fatal("%s: read from master failed: %s", 1648 __func__, strerror(errno)); 1649 } 1650 1651 type = buffer_get_int(&m); 1652 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1653 fatal("%s: out of sequence reply: my id %u theirs %u", 1654 __func__, muxclient_request_id, rid); 1655 switch (type) { 1656 case MUX_S_OK: 1657 break; 1658 case MUX_S_PERMISSION_DENIED: 1659 e = buffer_get_string(&m, NULL); 1660 fatal("Master refused termination request: %s", e); 1661 case MUX_S_FAILURE: 1662 e = buffer_get_string(&m, NULL); 1663 fatal("%s: termination request failed: %s", __func__, e); 1664 default: 1665 fatal("%s: unexpected response from master 0x%08x", 1666 __func__, type); 1667 } 1668 buffer_free(&m); 1669 muxclient_request_id++; 1670 } 1671 1672 static int 1673 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1674 { 1675 Buffer m; 1676 char *e, *fwd_desc; 1677 u_int type, rid; 1678 1679 fwd_desc = format_forward(ftype, fwd); 1680 debug("Requesting %s %s", 1681 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1682 free(fwd_desc); 1683 1684 buffer_init(&m); 1685 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1686 buffer_put_int(&m, muxclient_request_id); 1687 buffer_put_int(&m, ftype); 1688 if (fwd->listen_path != NULL) { 1689 buffer_put_cstring(&m, fwd->listen_path); 1690 } else { 1691 buffer_put_cstring(&m, 1692 fwd->listen_host == NULL ? "" : 1693 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1694 } 1695 buffer_put_int(&m, fwd->listen_port); 1696 if (fwd->connect_path != NULL) { 1697 buffer_put_cstring(&m, fwd->connect_path); 1698 } else { 1699 buffer_put_cstring(&m, 1700 fwd->connect_host == NULL ? "" : fwd->connect_host); 1701 } 1702 buffer_put_int(&m, fwd->connect_port); 1703 1704 if (mux_client_write_packet(fd, &m) != 0) 1705 fatal("%s: write packet: %s", __func__, strerror(errno)); 1706 1707 buffer_clear(&m); 1708 1709 /* Read their reply */ 1710 if (mux_client_read_packet(fd, &m) != 0) { 1711 buffer_free(&m); 1712 return -1; 1713 } 1714 1715 type = buffer_get_int(&m); 1716 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1717 fatal("%s: out of sequence reply: my id %u theirs %u", 1718 __func__, muxclient_request_id, rid); 1719 switch (type) { 1720 case MUX_S_OK: 1721 break; 1722 case MUX_S_REMOTE_PORT: 1723 if (cancel_flag) 1724 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1725 fwd->allocated_port = buffer_get_int(&m); 1726 verbose("Allocated port %u for remote forward to %s:%d", 1727 fwd->allocated_port, 1728 fwd->connect_host ? fwd->connect_host : "", 1729 fwd->connect_port); 1730 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1731 fprintf(stdout, "%i\n", fwd->allocated_port); 1732 break; 1733 case MUX_S_PERMISSION_DENIED: 1734 e = buffer_get_string(&m, NULL); 1735 buffer_free(&m); 1736 error("Master refused forwarding request: %s", e); 1737 return -1; 1738 case MUX_S_FAILURE: 1739 e = buffer_get_string(&m, NULL); 1740 buffer_free(&m); 1741 error("%s: forwarding request failed: %s", __func__, e); 1742 return -1; 1743 default: 1744 fatal("%s: unexpected response from master 0x%08x", 1745 __func__, type); 1746 } 1747 buffer_free(&m); 1748 1749 muxclient_request_id++; 1750 return 0; 1751 } 1752 1753 static int 1754 mux_client_forwards(int fd, int cancel_flag) 1755 { 1756 int i, ret = 0; 1757 1758 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1759 cancel_flag ? "cancel" : "request", 1760 options.num_local_forwards, options.num_remote_forwards); 1761 1762 /* XXX ExitOnForwardingFailure */ 1763 for (i = 0; i < options.num_local_forwards; i++) { 1764 if (mux_client_forward(fd, cancel_flag, 1765 options.local_forwards[i].connect_port == 0 ? 1766 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1767 options.local_forwards + i) != 0) 1768 ret = -1; 1769 } 1770 for (i = 0; i < options.num_remote_forwards; i++) { 1771 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1772 options.remote_forwards + i) != 0) 1773 ret = -1; 1774 } 1775 return ret; 1776 } 1777 1778 static int 1779 mux_client_request_session(int fd) 1780 { 1781 Buffer m; 1782 char *e, *term; 1783 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1784 extern char **environ; 1785 int devnull, rawmode; 1786 1787 debug3("%s: entering", __func__); 1788 1789 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1790 error("%s: master alive request failed", __func__); 1791 return -1; 1792 } 1793 1794 signal(SIGPIPE, SIG_IGN); 1795 1796 if (stdin_null_flag) { 1797 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1798 fatal("open(/dev/null): %s", strerror(errno)); 1799 if (dup2(devnull, STDIN_FILENO) == -1) 1800 fatal("dup2: %s", strerror(errno)); 1801 if (devnull > STDERR_FILENO) 1802 close(devnull); 1803 } 1804 1805 term = getenv("TERM"); 1806 1807 buffer_init(&m); 1808 buffer_put_int(&m, MUX_C_NEW_SESSION); 1809 buffer_put_int(&m, muxclient_request_id); 1810 buffer_put_cstring(&m, ""); /* reserved */ 1811 buffer_put_int(&m, tty_flag); 1812 buffer_put_int(&m, options.forward_x11); 1813 buffer_put_int(&m, options.forward_agent); 1814 buffer_put_int(&m, subsystem_flag); 1815 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1816 0xffffffff : (u_int)options.escape_char); 1817 buffer_put_cstring(&m, term == NULL ? "" : term); 1818 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1819 1820 if (options.num_send_env > 0 && environ != NULL) { 1821 /* Pass environment */ 1822 for (i = 0; environ[i] != NULL; i++) { 1823 if (env_permitted(environ[i])) { 1824 buffer_put_cstring(&m, environ[i]); 1825 } 1826 } 1827 } 1828 1829 if (mux_client_write_packet(fd, &m) != 0) 1830 fatal("%s: write packet: %s", __func__, strerror(errno)); 1831 1832 /* Send the stdio file descriptors */ 1833 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1834 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1835 mm_send_fd(fd, STDERR_FILENO) == -1) 1836 fatal("%s: send fds failed", __func__); 1837 1838 debug3("%s: session request sent", __func__); 1839 1840 /* Read their reply */ 1841 buffer_clear(&m); 1842 if (mux_client_read_packet(fd, &m) != 0) { 1843 error("%s: read from master failed: %s", 1844 __func__, strerror(errno)); 1845 buffer_free(&m); 1846 return -1; 1847 } 1848 1849 type = buffer_get_int(&m); 1850 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1851 fatal("%s: out of sequence reply: my id %u theirs %u", 1852 __func__, muxclient_request_id, rid); 1853 switch (type) { 1854 case MUX_S_SESSION_OPENED: 1855 sid = buffer_get_int(&m); 1856 debug("%s: master session id: %u", __func__, sid); 1857 break; 1858 case MUX_S_PERMISSION_DENIED: 1859 e = buffer_get_string(&m, NULL); 1860 buffer_free(&m); 1861 error("Master refused session request: %s", e); 1862 return -1; 1863 case MUX_S_FAILURE: 1864 e = buffer_get_string(&m, NULL); 1865 buffer_free(&m); 1866 error("%s: session request failed: %s", __func__, e); 1867 return -1; 1868 default: 1869 buffer_free(&m); 1870 error("%s: unexpected response from master 0x%08x", 1871 __func__, type); 1872 return -1; 1873 } 1874 muxclient_request_id++; 1875 1876 #ifdef __OpenBSD__ 1877 if (pledge("stdio proc tty", NULL) == -1) 1878 fatal("%s pledge(): %s", __func__, strerror(errno)); 1879 #endif 1880 1881 signal(SIGHUP, control_client_sighandler); 1882 signal(SIGINT, control_client_sighandler); 1883 signal(SIGTERM, control_client_sighandler); 1884 signal(SIGWINCH, control_client_sigrelay); 1885 1886 rawmode = tty_flag; 1887 if (tty_flag) 1888 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1889 1890 /* 1891 * Stick around until the controlee closes the client_fd. 1892 * Before it does, it is expected to write an exit message. 1893 * This process must read the value and wait for the closure of 1894 * the client_fd; if this one closes early, the multiplex master will 1895 * terminate early too (possibly losing data). 1896 */ 1897 for (exitval = 255, exitval_seen = 0;;) { 1898 buffer_clear(&m); 1899 if (mux_client_read_packet(fd, &m) != 0) 1900 break; 1901 type = buffer_get_int(&m); 1902 switch (type) { 1903 case MUX_S_TTY_ALLOC_FAIL: 1904 if ((esid = buffer_get_int(&m)) != sid) 1905 fatal("%s: tty alloc fail on unknown session: " 1906 "my id %u theirs %u", 1907 __func__, sid, esid); 1908 leave_raw_mode(options.request_tty == 1909 REQUEST_TTY_FORCE); 1910 rawmode = 0; 1911 continue; 1912 case MUX_S_EXIT_MESSAGE: 1913 if ((esid = buffer_get_int(&m)) != sid) 1914 fatal("%s: exit on unknown session: " 1915 "my id %u theirs %u", 1916 __func__, sid, esid); 1917 if (exitval_seen) 1918 fatal("%s: exitval sent twice", __func__); 1919 exitval = buffer_get_int(&m); 1920 exitval_seen = 1; 1921 continue; 1922 default: 1923 e = buffer_get_string(&m, NULL); 1924 fatal("%s: master returned error: %s", __func__, e); 1925 } 1926 } 1927 1928 close(fd); 1929 if (rawmode) 1930 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1931 1932 if (muxclient_terminate) { 1933 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1934 exitval = 255; 1935 } else if (!exitval_seen) { 1936 debug2("Control master terminated unexpectedly"); 1937 exitval = 255; 1938 } else 1939 debug2("Received exit status from master %d", exitval); 1940 1941 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1942 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1943 1944 exit(exitval); 1945 } 1946 1947 static int 1948 mux_client_request_stdio_fwd(int fd) 1949 { 1950 Buffer m; 1951 char *e; 1952 u_int type, rid, sid; 1953 int devnull; 1954 1955 debug3("%s: entering", __func__); 1956 1957 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1958 error("%s: master alive request failed", __func__); 1959 return -1; 1960 } 1961 1962 signal(SIGPIPE, SIG_IGN); 1963 1964 if (stdin_null_flag) { 1965 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1966 fatal("open(/dev/null): %s", strerror(errno)); 1967 if (dup2(devnull, STDIN_FILENO) == -1) 1968 fatal("dup2: %s", strerror(errno)); 1969 if (devnull > STDERR_FILENO) 1970 close(devnull); 1971 } 1972 1973 buffer_init(&m); 1974 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1975 buffer_put_int(&m, muxclient_request_id); 1976 buffer_put_cstring(&m, ""); /* reserved */ 1977 buffer_put_cstring(&m, options.stdio_forward_host); 1978 buffer_put_int(&m, options.stdio_forward_port); 1979 1980 if (mux_client_write_packet(fd, &m) != 0) 1981 fatal("%s: write packet: %s", __func__, strerror(errno)); 1982 1983 /* Send the stdio file descriptors */ 1984 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1985 mm_send_fd(fd, STDOUT_FILENO) == -1) 1986 fatal("%s: send fds failed", __func__); 1987 1988 #ifdef __OpenBSD__ 1989 if (pledge("stdio proc tty", NULL) == -1) 1990 fatal("%s pledge(): %s", __func__, strerror(errno)); 1991 #endif 1992 1993 debug3("%s: stdio forward request sent", __func__); 1994 1995 /* Read their reply */ 1996 buffer_clear(&m); 1997 1998 if (mux_client_read_packet(fd, &m) != 0) { 1999 error("%s: read from master failed: %s", 2000 __func__, strerror(errno)); 2001 buffer_free(&m); 2002 return -1; 2003 } 2004 2005 type = buffer_get_int(&m); 2006 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2007 fatal("%s: out of sequence reply: my id %u theirs %u", 2008 __func__, muxclient_request_id, rid); 2009 switch (type) { 2010 case MUX_S_SESSION_OPENED: 2011 sid = buffer_get_int(&m); 2012 debug("%s: master session id: %u", __func__, sid); 2013 break; 2014 case MUX_S_PERMISSION_DENIED: 2015 e = buffer_get_string(&m, NULL); 2016 buffer_free(&m); 2017 fatal("Master refused stdio forwarding request: %s", e); 2018 case MUX_S_FAILURE: 2019 e = buffer_get_string(&m, NULL); 2020 buffer_free(&m); 2021 fatal("Stdio forwarding request failed: %s", e); 2022 default: 2023 buffer_free(&m); 2024 error("%s: unexpected response from master 0x%08x", 2025 __func__, type); 2026 return -1; 2027 } 2028 muxclient_request_id++; 2029 2030 signal(SIGHUP, control_client_sighandler); 2031 signal(SIGINT, control_client_sighandler); 2032 signal(SIGTERM, control_client_sighandler); 2033 signal(SIGWINCH, control_client_sigrelay); 2034 2035 /* 2036 * Stick around until the controlee closes the client_fd. 2037 */ 2038 buffer_clear(&m); 2039 if (mux_client_read_packet(fd, &m) != 0) { 2040 if (errno == EPIPE || 2041 (errno == EINTR && muxclient_terminate != 0)) 2042 return 0; 2043 fatal("%s: mux_client_read_packet: %s", 2044 __func__, strerror(errno)); 2045 } 2046 fatal("%s: master returned unexpected message %u", __func__, type); 2047 } 2048 2049 static void 2050 mux_client_request_stop_listening(int fd) 2051 { 2052 Buffer m; 2053 char *e; 2054 u_int type, rid; 2055 2056 debug3("%s: entering", __func__); 2057 2058 buffer_init(&m); 2059 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2060 buffer_put_int(&m, muxclient_request_id); 2061 2062 if (mux_client_write_packet(fd, &m) != 0) 2063 fatal("%s: write packet: %s", __func__, strerror(errno)); 2064 2065 buffer_clear(&m); 2066 2067 /* Read their reply */ 2068 if (mux_client_read_packet(fd, &m) != 0) 2069 fatal("%s: read from master failed: %s", 2070 __func__, strerror(errno)); 2071 2072 type = buffer_get_int(&m); 2073 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2074 fatal("%s: out of sequence reply: my id %u theirs %u", 2075 __func__, muxclient_request_id, rid); 2076 switch (type) { 2077 case MUX_S_OK: 2078 break; 2079 case MUX_S_PERMISSION_DENIED: 2080 e = buffer_get_string(&m, NULL); 2081 fatal("Master refused stop listening request: %s", e); 2082 case MUX_S_FAILURE: 2083 e = buffer_get_string(&m, NULL); 2084 fatal("%s: stop listening request failed: %s", __func__, e); 2085 default: 2086 fatal("%s: unexpected response from master 0x%08x", 2087 __func__, type); 2088 } 2089 buffer_free(&m); 2090 muxclient_request_id++; 2091 } 2092 2093 /* Multiplex client main loop. */ 2094 void 2095 muxclient(const char *path) 2096 { 2097 struct sockaddr_un addr; 2098 int sock; 2099 u_int pid; 2100 2101 if (muxclient_command == 0) { 2102 if (options.stdio_forward_host != NULL) 2103 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2104 else 2105 muxclient_command = SSHMUX_COMMAND_OPEN; 2106 } 2107 2108 switch (options.control_master) { 2109 case SSHCTL_MASTER_AUTO: 2110 case SSHCTL_MASTER_AUTO_ASK: 2111 debug("auto-mux: Trying existing master"); 2112 /* FALLTHROUGH */ 2113 case SSHCTL_MASTER_NO: 2114 break; 2115 default: 2116 return; 2117 } 2118 2119 memset(&addr, '\0', sizeof(addr)); 2120 addr.sun_family = AF_UNIX; 2121 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 2122 strlen(path) + 1; 2123 2124 if (strlcpy(addr.sun_path, path, 2125 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2126 fatal("ControlPath too long"); 2127 2128 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2129 fatal("%s socket(): %s", __func__, strerror(errno)); 2130 2131 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 2132 switch (muxclient_command) { 2133 case SSHMUX_COMMAND_OPEN: 2134 case SSHMUX_COMMAND_STDIO_FWD: 2135 break; 2136 default: 2137 fatal("Control socket connect(%.100s): %s", path, 2138 strerror(errno)); 2139 } 2140 if (errno == ECONNREFUSED && 2141 options.control_master != SSHCTL_MASTER_NO) { 2142 debug("Stale control socket %.100s, unlinking", path); 2143 unlink(path); 2144 } else if (errno == ENOENT) { 2145 debug("Control socket \"%.100s\" does not exist", path); 2146 } else { 2147 error("Control socket connect(%.100s): %s", path, 2148 strerror(errno)); 2149 } 2150 close(sock); 2151 return; 2152 } 2153 set_nonblock(sock); 2154 2155 if (mux_client_hello_exchange(sock) != 0) { 2156 error("%s: master hello exchange failed", __func__); 2157 close(sock); 2158 return; 2159 } 2160 2161 switch (muxclient_command) { 2162 case SSHMUX_COMMAND_ALIVE_CHECK: 2163 if ((pid = mux_client_request_alive(sock)) == 0) 2164 fatal("%s: master alive check failed", __func__); 2165 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2166 exit(0); 2167 case SSHMUX_COMMAND_TERMINATE: 2168 mux_client_request_terminate(sock); 2169 fprintf(stderr, "Exit request sent.\r\n"); 2170 exit(0); 2171 case SSHMUX_COMMAND_FORWARD: 2172 if (mux_client_forwards(sock, 0) != 0) 2173 fatal("%s: master forward request failed", __func__); 2174 exit(0); 2175 case SSHMUX_COMMAND_OPEN: 2176 if (mux_client_forwards(sock, 0) != 0) { 2177 error("%s: master forward request failed", __func__); 2178 return; 2179 } 2180 mux_client_request_session(sock); 2181 return; 2182 case SSHMUX_COMMAND_STDIO_FWD: 2183 mux_client_request_stdio_fwd(sock); 2184 exit(0); 2185 case SSHMUX_COMMAND_STOP: 2186 mux_client_request_stop_listening(sock); 2187 fprintf(stderr, "Stop listening request sent.\r\n"); 2188 exit(0); 2189 case SSHMUX_COMMAND_CANCEL_FWD: 2190 if (mux_client_forwards(sock, 1) != 0) 2191 error("%s: master cancel forward request failed", 2192 __func__); 2193 exit(0); 2194 default: 2195 fatal("unrecognised muxclient_command %d", muxclient_command); 2196 } 2197 } 2198