1 /* $OpenBSD: mux.c,v 1.60 2016/06/03 03:14:41 dtucker 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 79 /* Context for session open confirmation callback */ 80 struct mux_session_confirm_ctx { 81 u_int want_tty; 82 u_int want_subsys; 83 u_int want_x_fwd; 84 u_int want_agent_fwd; 85 Buffer cmd; 86 char *term; 87 struct termios tio; 88 char **env; 89 u_int rid; 90 }; 91 92 /* Context for stdio fwd open confirmation callback */ 93 struct mux_stdio_confirm_ctx { 94 u_int rid; 95 }; 96 97 /* Context for global channel callback */ 98 struct mux_channel_confirm_ctx { 99 u_int cid; /* channel id */ 100 u_int rid; /* request id */ 101 int fid; /* forward id */ 102 }; 103 104 /* fd to control socket */ 105 int muxserver_sock = -1; 106 107 /* client request id */ 108 u_int muxclient_request_id = 0; 109 110 /* Multiplexing control command */ 111 u_int muxclient_command = 0; 112 113 /* Set when signalled. */ 114 static volatile sig_atomic_t muxclient_terminate = 0; 115 116 /* PID of multiplex server */ 117 static u_int muxserver_pid = 0; 118 119 static Channel *mux_listener_channel = NULL; 120 121 struct mux_master_state { 122 int hello_rcvd; 123 }; 124 125 /* mux protocol messages */ 126 #define MUX_MSG_HELLO 0x00000001 127 #define MUX_C_NEW_SESSION 0x10000002 128 #define MUX_C_ALIVE_CHECK 0x10000004 129 #define MUX_C_TERMINATE 0x10000005 130 #define MUX_C_OPEN_FWD 0x10000006 131 #define MUX_C_CLOSE_FWD 0x10000007 132 #define MUX_C_NEW_STDIO_FWD 0x10000008 133 #define MUX_C_STOP_LISTENING 0x10000009 134 #define MUX_S_OK 0x80000001 135 #define MUX_S_PERMISSION_DENIED 0x80000002 136 #define MUX_S_FAILURE 0x80000003 137 #define MUX_S_EXIT_MESSAGE 0x80000004 138 #define MUX_S_ALIVE 0x80000005 139 #define MUX_S_SESSION_OPENED 0x80000006 140 #define MUX_S_REMOTE_PORT 0x80000007 141 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 142 143 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 144 #define MUX_FWD_LOCAL 1 145 #define MUX_FWD_REMOTE 2 146 #define MUX_FWD_DYNAMIC 3 147 148 static void mux_session_confirm(int, int, void *); 149 static void mux_stdio_confirm(int, int, void *); 150 151 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 152 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 153 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 154 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 155 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 156 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 157 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 158 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 159 160 static const struct { 161 u_int type; 162 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 163 } mux_master_handlers[] = { 164 { MUX_MSG_HELLO, process_mux_master_hello }, 165 { MUX_C_NEW_SESSION, process_mux_new_session }, 166 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 167 { MUX_C_TERMINATE, process_mux_terminate }, 168 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 169 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 170 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 171 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 172 { 0, NULL } 173 }; 174 175 /* Cleanup callback fired on closure of mux slave _session_ channel */ 176 /* ARGSUSED */ 177 static void 178 mux_master_session_cleanup_cb(int cid, void *unused) 179 { 180 Channel *cc, *c = channel_by_id(cid); 181 182 debug3("%s: entering for channel %d", __func__, cid); 183 if (c == NULL) 184 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 185 if (c->ctl_chan != -1) { 186 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 187 fatal("%s: channel %d missing control channel %d", 188 __func__, c->self, c->ctl_chan); 189 c->ctl_chan = -1; 190 cc->remote_id = -1; 191 chan_rcvd_oclose(cc); 192 } 193 channel_cancel_cleanup(c->self); 194 } 195 196 /* Cleanup callback fired on closure of mux slave _control_ channel */ 197 /* ARGSUSED */ 198 static void 199 mux_master_control_cleanup_cb(int cid, void *unused) 200 { 201 Channel *sc, *c = channel_by_id(cid); 202 203 debug3("%s: entering for channel %d", __func__, cid); 204 if (c == NULL) 205 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 206 if (c->remote_id != -1) { 207 if ((sc = channel_by_id(c->remote_id)) == NULL) 208 fatal("%s: channel %d missing session channel %d", 209 __func__, c->self, c->remote_id); 210 c->remote_id = -1; 211 sc->ctl_chan = -1; 212 if (sc->type != SSH_CHANNEL_OPEN && 213 sc->type != SSH_CHANNEL_OPENING) { 214 debug2("%s: channel %d: not open", __func__, sc->self); 215 chan_mark_dead(sc); 216 } else { 217 if (sc->istate == CHAN_INPUT_OPEN) 218 chan_read_failed(sc); 219 if (sc->ostate == CHAN_OUTPUT_OPEN) 220 chan_write_failed(sc); 221 } 222 } 223 channel_cancel_cleanup(c->self); 224 } 225 226 /* Check mux client environment variables before passing them to mux master. */ 227 static int 228 env_permitted(char *env) 229 { 230 int i, ret; 231 char name[1024], *cp; 232 233 if ((cp = strchr(env, '=')) == NULL || cp == env) 234 return 0; 235 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 236 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 237 error("env_permitted: name '%.100s...' too long", env); 238 return 0; 239 } 240 241 for (i = 0; i < options.num_send_env; i++) 242 if (match_pattern(name, options.send_env[i])) 243 return 1; 244 245 return 0; 246 } 247 248 /* Mux master protocol message handlers */ 249 250 static int 251 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 252 { 253 u_int ver; 254 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 255 256 if (state == NULL) 257 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 258 if (state->hello_rcvd) { 259 error("%s: HELLO received twice", __func__); 260 return -1; 261 } 262 if (buffer_get_int_ret(&ver, m) != 0) { 263 malf: 264 error("%s: malformed message", __func__); 265 return -1; 266 } 267 if (ver != SSHMUX_VER) { 268 error("Unsupported multiplexing protocol version %d " 269 "(expected %d)", ver, SSHMUX_VER); 270 return -1; 271 } 272 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 273 274 /* No extensions are presently defined */ 275 while (buffer_len(m) > 0) { 276 char *name = buffer_get_string_ret(m, NULL); 277 char *value = buffer_get_string_ret(m, NULL); 278 279 if (name == NULL || value == NULL) { 280 free(name); 281 free(value); 282 goto malf; 283 } 284 debug2("Unrecognised slave extension \"%s\"", name); 285 free(name); 286 free(value); 287 } 288 state->hello_rcvd = 1; 289 return 0; 290 } 291 292 static int 293 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 294 { 295 Channel *nc; 296 struct mux_session_confirm_ctx *cctx; 297 char *reserved, *cmd, *cp; 298 u_int i, j, len, env_len, escape_char, window, packetmax; 299 int new_fd[3]; 300 301 /* Reply for SSHMUX_COMMAND_OPEN */ 302 cctx = xcalloc(1, sizeof(*cctx)); 303 cctx->term = NULL; 304 cctx->rid = rid; 305 cmd = reserved = NULL; 306 cctx->env = NULL; 307 env_len = 0; 308 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 309 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 310 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 311 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 312 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 313 buffer_get_int_ret(&escape_char, m) != 0 || 314 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 315 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 316 malf: 317 free(cmd); 318 free(reserved); 319 for (j = 0; j < env_len; j++) 320 free(cctx->env[j]); 321 free(cctx->env); 322 free(cctx->term); 323 free(cctx); 324 error("%s: malformed message", __func__); 325 return -1; 326 } 327 free(reserved); 328 reserved = NULL; 329 330 while (buffer_len(m) > 0) { 331 #define MUX_MAX_ENV_VARS 4096 332 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 333 goto malf; 334 if (!env_permitted(cp)) { 335 free(cp); 336 continue; 337 } 338 cctx->env = xreallocarray(cctx->env, env_len + 2, 339 sizeof(*cctx->env)); 340 cctx->env[env_len++] = cp; 341 cctx->env[env_len] = NULL; 342 if (env_len > MUX_MAX_ENV_VARS) { 343 error(">%d environment variables received, ignoring " 344 "additional", MUX_MAX_ENV_VARS); 345 break; 346 } 347 } 348 349 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 350 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 351 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 352 cctx->want_subsys, cctx->term, cmd, env_len); 353 354 buffer_init(&cctx->cmd); 355 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 356 free(cmd); 357 cmd = NULL; 358 359 /* Gather fds from client */ 360 for(i = 0; i < 3; i++) { 361 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 362 error("%s: failed to receive fd %d from slave", 363 __func__, i); 364 for (j = 0; j < i; j++) 365 close(new_fd[j]); 366 for (j = 0; j < env_len; j++) 367 free(cctx->env[j]); 368 free(cctx->env); 369 free(cctx->term); 370 buffer_free(&cctx->cmd); 371 free(cctx); 372 373 /* prepare reply */ 374 buffer_put_int(r, MUX_S_FAILURE); 375 buffer_put_int(r, rid); 376 buffer_put_cstring(r, 377 "did not receive file descriptors"); 378 return -1; 379 } 380 } 381 382 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 383 new_fd[0], new_fd[1], new_fd[2]); 384 385 /* XXX support multiple child sessions in future */ 386 if (c->remote_id != -1) { 387 debug2("%s: session already open", __func__); 388 /* prepare reply */ 389 buffer_put_int(r, MUX_S_FAILURE); 390 buffer_put_int(r, rid); 391 buffer_put_cstring(r, "Multiple sessions not supported"); 392 cleanup: 393 close(new_fd[0]); 394 close(new_fd[1]); 395 close(new_fd[2]); 396 free(cctx->term); 397 if (env_len != 0) { 398 for (i = 0; i < env_len; i++) 399 free(cctx->env[i]); 400 free(cctx->env); 401 } 402 buffer_free(&cctx->cmd); 403 free(cctx); 404 return 0; 405 } 406 407 if (options.control_master == SSHCTL_MASTER_ASK || 408 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 409 if (!ask_permission("Allow shared connection to %s? ", host)) { 410 debug2("%s: session refused by user", __func__); 411 /* prepare reply */ 412 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 413 buffer_put_int(r, rid); 414 buffer_put_cstring(r, "Permission denied"); 415 goto cleanup; 416 } 417 } 418 419 /* Try to pick up ttymodes from client before it goes raw */ 420 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 421 error("%s: tcgetattr: %s", __func__, strerror(errno)); 422 423 /* enable nonblocking unless tty */ 424 if (!isatty(new_fd[0])) 425 set_nonblock(new_fd[0]); 426 if (!isatty(new_fd[1])) 427 set_nonblock(new_fd[1]); 428 if (!isatty(new_fd[2])) 429 set_nonblock(new_fd[2]); 430 431 window = CHAN_SES_WINDOW_DEFAULT; 432 packetmax = CHAN_SES_PACKET_DEFAULT; 433 if (cctx->want_tty) { 434 window >>= 1; 435 packetmax >>= 1; 436 } 437 438 nc = channel_new("session", SSH_CHANNEL_OPENING, 439 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 440 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 441 442 nc->ctl_chan = c->self; /* link session -> control channel */ 443 c->remote_id = nc->self; /* link control -> session channel */ 444 445 if (cctx->want_tty && escape_char != 0xffffffff) { 446 channel_register_filter(nc->self, 447 client_simple_escape_filter, NULL, 448 client_filter_cleanup, 449 client_new_escape_filter_ctx((int)escape_char)); 450 } 451 452 debug2("%s: channel_new: %d linked to control channel %d", 453 __func__, nc->self, nc->ctl_chan); 454 455 channel_send_open(nc->self); 456 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 457 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 458 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 459 460 /* reply is deferred, sent by mux_session_confirm */ 461 return 0; 462 } 463 464 static int 465 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 466 { 467 debug2("%s: channel %d: alive check", __func__, c->self); 468 469 /* prepare reply */ 470 buffer_put_int(r, MUX_S_ALIVE); 471 buffer_put_int(r, rid); 472 buffer_put_int(r, (u_int)getpid()); 473 474 return 0; 475 } 476 477 static int 478 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 479 { 480 debug2("%s: channel %d: terminate request", __func__, c->self); 481 482 if (options.control_master == SSHCTL_MASTER_ASK || 483 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 484 if (!ask_permission("Terminate shared connection to %s? ", 485 host)) { 486 debug2("%s: termination refused by user", __func__); 487 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 488 buffer_put_int(r, rid); 489 buffer_put_cstring(r, "Permission denied"); 490 return 0; 491 } 492 } 493 494 quit_pending = 1; 495 buffer_put_int(r, MUX_S_OK); 496 buffer_put_int(r, rid); 497 /* XXX exit happens too soon - message never makes it to client */ 498 return 0; 499 } 500 501 static char * 502 format_forward(u_int ftype, struct Forward *fwd) 503 { 504 char *ret; 505 506 switch (ftype) { 507 case MUX_FWD_LOCAL: 508 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 509 (fwd->listen_path != NULL) ? fwd->listen_path : 510 (fwd->listen_host == NULL) ? 511 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 512 fwd->listen_host, fwd->listen_port, 513 (fwd->connect_path != NULL) ? fwd->connect_path : 514 fwd->connect_host, fwd->connect_port); 515 break; 516 case MUX_FWD_DYNAMIC: 517 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 518 (fwd->listen_host == NULL) ? 519 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 520 fwd->listen_host, fwd->listen_port); 521 break; 522 case MUX_FWD_REMOTE: 523 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 524 (fwd->listen_path != NULL) ? fwd->listen_path : 525 (fwd->listen_host == NULL) ? 526 "LOCALHOST" : fwd->listen_host, 527 fwd->listen_port, 528 (fwd->connect_path != NULL) ? fwd->connect_path : 529 fwd->connect_host, fwd->connect_port); 530 break; 531 default: 532 fatal("%s: unknown forward type %u", __func__, ftype); 533 } 534 return ret; 535 } 536 537 static int 538 compare_host(const char *a, const char *b) 539 { 540 if (a == NULL && b == NULL) 541 return 1; 542 if (a == NULL || b == NULL) 543 return 0; 544 return strcmp(a, b) == 0; 545 } 546 547 static int 548 compare_forward(struct Forward *a, struct Forward *b) 549 { 550 if (!compare_host(a->listen_host, b->listen_host)) 551 return 0; 552 if (!compare_host(a->listen_path, b->listen_path)) 553 return 0; 554 if (a->listen_port != b->listen_port) 555 return 0; 556 if (!compare_host(a->connect_host, b->connect_host)) 557 return 0; 558 if (!compare_host(a->connect_path, b->connect_path)) 559 return 0; 560 if (a->connect_port != b->connect_port) 561 return 0; 562 563 return 1; 564 } 565 566 static void 567 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 568 { 569 struct mux_channel_confirm_ctx *fctx = ctxt; 570 char *failmsg = NULL; 571 struct Forward *rfwd; 572 Channel *c; 573 Buffer out; 574 575 if ((c = channel_by_id(fctx->cid)) == NULL) { 576 /* no channel for reply */ 577 error("%s: unknown channel", __func__); 578 return; 579 } 580 buffer_init(&out); 581 if (fctx->fid >= options.num_remote_forwards || 582 (options.remote_forwards[fctx->fid].connect_path == NULL && 583 options.remote_forwards[fctx->fid].connect_host == NULL)) { 584 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 585 goto fail; 586 } 587 rfwd = &options.remote_forwards[fctx->fid]; 588 debug("%s: %s for: listen %d, connect %s:%d", __func__, 589 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 590 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 591 rfwd->connect_host, rfwd->connect_port); 592 if (type == SSH2_MSG_REQUEST_SUCCESS) { 593 if (rfwd->listen_port == 0) { 594 rfwd->allocated_port = packet_get_int(); 595 debug("Allocated port %u for mux remote forward" 596 " to %s:%d", rfwd->allocated_port, 597 rfwd->connect_host, rfwd->connect_port); 598 buffer_put_int(&out, MUX_S_REMOTE_PORT); 599 buffer_put_int(&out, fctx->rid); 600 buffer_put_int(&out, rfwd->allocated_port); 601 channel_update_permitted_opens(rfwd->handle, 602 rfwd->allocated_port); 603 } else { 604 buffer_put_int(&out, MUX_S_OK); 605 buffer_put_int(&out, fctx->rid); 606 } 607 goto out; 608 } else { 609 if (rfwd->listen_port == 0) 610 channel_update_permitted_opens(rfwd->handle, -1); 611 if (rfwd->listen_path != NULL) 612 xasprintf(&failmsg, "remote port forwarding failed for " 613 "listen path %s", rfwd->listen_path); 614 else 615 xasprintf(&failmsg, "remote port forwarding failed for " 616 "listen port %d", rfwd->listen_port); 617 618 debug2("%s: clearing registered forwarding for listen %d, " 619 "connect %s:%d", __func__, rfwd->listen_port, 620 rfwd->connect_path ? rfwd->connect_path : 621 rfwd->connect_host, rfwd->connect_port); 622 623 free(rfwd->listen_host); 624 free(rfwd->listen_path); 625 free(rfwd->connect_host); 626 free(rfwd->connect_path); 627 memset(rfwd, 0, sizeof(*rfwd)); 628 } 629 fail: 630 error("%s: %s", __func__, failmsg); 631 buffer_put_int(&out, MUX_S_FAILURE); 632 buffer_put_int(&out, fctx->rid); 633 buffer_put_cstring(&out, failmsg); 634 free(failmsg); 635 out: 636 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 637 buffer_free(&out); 638 if (c->mux_pause <= 0) 639 fatal("%s: mux_pause %d", __func__, c->mux_pause); 640 c->mux_pause = 0; /* start processing messages again */ 641 } 642 643 static int 644 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 645 { 646 struct Forward fwd; 647 char *fwd_desc = NULL; 648 char *listen_addr, *connect_addr; 649 u_int ftype; 650 u_int lport, cport; 651 int i, ret = 0, freefwd = 1; 652 653 memset(&fwd, 0, sizeof(fwd)); 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 memset(&fwd, 0, sizeof(fwd)); 823 824 if (buffer_get_int_ret(&ftype, m) != 0 || 825 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 826 buffer_get_int_ret(&lport, m) != 0 || 827 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 828 buffer_get_int_ret(&cport, m) != 0 || 829 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 830 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 831 error("%s: malformed message", __func__); 832 ret = -1; 833 goto out; 834 } 835 836 if (*listen_addr == '\0') { 837 free(listen_addr); 838 listen_addr = NULL; 839 } 840 if (*connect_addr == '\0') { 841 free(connect_addr); 842 connect_addr = NULL; 843 } 844 845 memset(&fwd, 0, sizeof(fwd)); 846 fwd.listen_port = lport; 847 if (fwd.listen_port == PORT_STREAMLOCAL) 848 fwd.listen_path = listen_addr; 849 else 850 fwd.listen_host = listen_addr; 851 fwd.connect_port = cport; 852 if (fwd.connect_port == PORT_STREAMLOCAL) 853 fwd.connect_path = connect_addr; 854 else 855 fwd.connect_host = connect_addr; 856 857 debug2("%s: channel %d: request cancel %s", __func__, c->self, 858 (fwd_desc = format_forward(ftype, &fwd))); 859 860 /* make sure this has been requested */ 861 found_fwd = NULL; 862 switch (ftype) { 863 case MUX_FWD_LOCAL: 864 case MUX_FWD_DYNAMIC: 865 for (i = 0; i < options.num_local_forwards; i++) { 866 if (compare_forward(&fwd, 867 options.local_forwards + i)) { 868 found_fwd = options.local_forwards + i; 869 break; 870 } 871 } 872 break; 873 case MUX_FWD_REMOTE: 874 for (i = 0; i < options.num_remote_forwards; i++) { 875 if (compare_forward(&fwd, 876 options.remote_forwards + i)) { 877 found_fwd = options.remote_forwards + i; 878 break; 879 } 880 } 881 break; 882 } 883 884 if (found_fwd == NULL) 885 error_reason = "port not forwarded"; 886 else if (ftype == MUX_FWD_REMOTE) { 887 /* 888 * This shouldn't fail unless we confused the host/port 889 * between options.remote_forwards and permitted_opens. 890 * However, for dynamic allocated listen ports we need 891 * to use the actual listen port. 892 */ 893 if (channel_request_rforward_cancel(found_fwd) == -1) 894 error_reason = "port not in permitted opens"; 895 } else { /* local and dynamic forwards */ 896 /* Ditto */ 897 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 898 &options.fwd_opts) == -1) 899 error_reason = "port not found"; 900 } 901 902 if (error_reason == NULL) { 903 buffer_put_int(r, MUX_S_OK); 904 buffer_put_int(r, rid); 905 906 free(found_fwd->listen_host); 907 free(found_fwd->listen_path); 908 free(found_fwd->connect_host); 909 free(found_fwd->connect_path); 910 found_fwd->listen_host = found_fwd->connect_host = NULL; 911 found_fwd->listen_path = found_fwd->connect_path = NULL; 912 found_fwd->listen_port = found_fwd->connect_port = 0; 913 } else { 914 buffer_put_int(r, MUX_S_FAILURE); 915 buffer_put_int(r, rid); 916 buffer_put_cstring(r, error_reason); 917 } 918 out: 919 free(fwd_desc); 920 free(listen_addr); 921 free(connect_addr); 922 923 return ret; 924 } 925 926 static int 927 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 928 { 929 Channel *nc; 930 char *reserved, *chost; 931 u_int cport, i, j; 932 int new_fd[2]; 933 struct mux_stdio_confirm_ctx *cctx; 934 935 chost = reserved = NULL; 936 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 937 (chost = buffer_get_string_ret(m, NULL)) == NULL || 938 buffer_get_int_ret(&cport, m) != 0) { 939 free(reserved); 940 free(chost); 941 error("%s: malformed message", __func__); 942 return -1; 943 } 944 free(reserved); 945 946 debug2("%s: channel %d: request stdio fwd to %s:%u", 947 __func__, c->self, chost, cport); 948 949 /* Gather fds from client */ 950 for(i = 0; i < 2; i++) { 951 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 952 error("%s: failed to receive fd %d from slave", 953 __func__, i); 954 for (j = 0; j < i; j++) 955 close(new_fd[j]); 956 free(chost); 957 958 /* prepare reply */ 959 buffer_put_int(r, MUX_S_FAILURE); 960 buffer_put_int(r, rid); 961 buffer_put_cstring(r, 962 "did not receive file descriptors"); 963 return -1; 964 } 965 } 966 967 debug3("%s: got fds stdin %d, stdout %d", __func__, 968 new_fd[0], new_fd[1]); 969 970 /* XXX support multiple child sessions in future */ 971 if (c->remote_id != -1) { 972 debug2("%s: session already open", __func__); 973 /* prepare reply */ 974 buffer_put_int(r, MUX_S_FAILURE); 975 buffer_put_int(r, rid); 976 buffer_put_cstring(r, "Multiple sessions not supported"); 977 cleanup: 978 close(new_fd[0]); 979 close(new_fd[1]); 980 free(chost); 981 return 0; 982 } 983 984 if (options.control_master == SSHCTL_MASTER_ASK || 985 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 986 if (!ask_permission("Allow forward to %s:%u? ", 987 chost, cport)) { 988 debug2("%s: stdio fwd refused by user", __func__); 989 /* prepare reply */ 990 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 991 buffer_put_int(r, rid); 992 buffer_put_cstring(r, "Permission denied"); 993 goto cleanup; 994 } 995 } 996 997 /* enable nonblocking unless tty */ 998 if (!isatty(new_fd[0])) 999 set_nonblock(new_fd[0]); 1000 if (!isatty(new_fd[1])) 1001 set_nonblock(new_fd[1]); 1002 1003 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1004 1005 nc->ctl_chan = c->self; /* link session -> control channel */ 1006 c->remote_id = nc->self; /* link control -> session channel */ 1007 1008 debug2("%s: channel_new: %d linked to control channel %d", 1009 __func__, nc->self, nc->ctl_chan); 1010 1011 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1012 1013 cctx = xcalloc(1, sizeof(*cctx)); 1014 cctx->rid = rid; 1015 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1016 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1017 1018 /* reply is deferred, sent by mux_session_confirm */ 1019 return 0; 1020 } 1021 1022 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1023 static void 1024 mux_stdio_confirm(int id, int success, void *arg) 1025 { 1026 struct mux_stdio_confirm_ctx *cctx = arg; 1027 Channel *c, *cc; 1028 Buffer reply; 1029 1030 if (cctx == NULL) 1031 fatal("%s: cctx == NULL", __func__); 1032 if ((c = channel_by_id(id)) == NULL) 1033 fatal("%s: no channel for id %d", __func__, id); 1034 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1035 fatal("%s: channel %d lacks control channel %d", __func__, 1036 id, c->ctl_chan); 1037 1038 if (!success) { 1039 debug3("%s: sending failure reply", __func__); 1040 /* prepare reply */ 1041 buffer_init(&reply); 1042 buffer_put_int(&reply, MUX_S_FAILURE); 1043 buffer_put_int(&reply, cctx->rid); 1044 buffer_put_cstring(&reply, "Session open refused by peer"); 1045 goto done; 1046 } 1047 1048 debug3("%s: sending success reply", __func__); 1049 /* prepare reply */ 1050 buffer_init(&reply); 1051 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1052 buffer_put_int(&reply, cctx->rid); 1053 buffer_put_int(&reply, c->self); 1054 1055 done: 1056 /* Send reply */ 1057 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1058 buffer_free(&reply); 1059 1060 if (cc->mux_pause <= 0) 1061 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1062 cc->mux_pause = 0; /* start processing messages again */ 1063 c->open_confirm_ctx = NULL; 1064 free(cctx); 1065 } 1066 1067 static int 1068 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1069 { 1070 debug("%s: channel %d: stop listening", __func__, c->self); 1071 1072 if (options.control_master == SSHCTL_MASTER_ASK || 1073 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1074 if (!ask_permission("Disable further multiplexing on shared " 1075 "connection to %s? ", host)) { 1076 debug2("%s: stop listen refused by user", __func__); 1077 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1078 buffer_put_int(r, rid); 1079 buffer_put_cstring(r, "Permission denied"); 1080 return 0; 1081 } 1082 } 1083 1084 if (mux_listener_channel != NULL) { 1085 channel_free(mux_listener_channel); 1086 client_stop_mux(); 1087 free(options.control_path); 1088 options.control_path = NULL; 1089 mux_listener_channel = NULL; 1090 muxserver_sock = -1; 1091 } 1092 1093 /* prepare reply */ 1094 buffer_put_int(r, MUX_S_OK); 1095 buffer_put_int(r, rid); 1096 1097 return 0; 1098 } 1099 1100 /* Channel callbacks fired on read/write from mux slave fd */ 1101 static int 1102 mux_master_read_cb(Channel *c) 1103 { 1104 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1105 Buffer in, out; 1106 const u_char *ptr; 1107 u_int type, rid, have, i; 1108 int ret = -1; 1109 1110 /* Setup ctx and */ 1111 if (c->mux_ctx == NULL) { 1112 state = xcalloc(1, sizeof(*state)); 1113 c->mux_ctx = state; 1114 channel_register_cleanup(c->self, 1115 mux_master_control_cleanup_cb, 0); 1116 1117 /* Send hello */ 1118 buffer_init(&out); 1119 buffer_put_int(&out, MUX_MSG_HELLO); 1120 buffer_put_int(&out, SSHMUX_VER); 1121 /* no extensions */ 1122 buffer_put_string(&c->output, buffer_ptr(&out), 1123 buffer_len(&out)); 1124 buffer_free(&out); 1125 debug3("%s: channel %d: hello sent", __func__, c->self); 1126 return 0; 1127 } 1128 1129 buffer_init(&in); 1130 buffer_init(&out); 1131 1132 /* Channel code ensures that we receive whole packets */ 1133 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1134 malf: 1135 error("%s: malformed message", __func__); 1136 goto out; 1137 } 1138 buffer_append(&in, ptr, have); 1139 1140 if (buffer_get_int_ret(&type, &in) != 0) 1141 goto malf; 1142 debug3("%s: channel %d packet type 0x%08x len %u", 1143 __func__, c->self, type, buffer_len(&in)); 1144 1145 if (type == MUX_MSG_HELLO) 1146 rid = 0; 1147 else { 1148 if (!state->hello_rcvd) { 1149 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1150 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1151 goto out; 1152 } 1153 if (buffer_get_int_ret(&rid, &in) != 0) 1154 goto malf; 1155 } 1156 1157 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1158 if (type == mux_master_handlers[i].type) { 1159 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1160 break; 1161 } 1162 } 1163 if (mux_master_handlers[i].handler == NULL) { 1164 error("%s: unsupported mux message 0x%08x", __func__, type); 1165 buffer_put_int(&out, MUX_S_FAILURE); 1166 buffer_put_int(&out, rid); 1167 buffer_put_cstring(&out, "unsupported request"); 1168 ret = 0; 1169 } 1170 /* Enqueue reply packet */ 1171 if (buffer_len(&out) != 0) { 1172 buffer_put_string(&c->output, buffer_ptr(&out), 1173 buffer_len(&out)); 1174 } 1175 out: 1176 buffer_free(&in); 1177 buffer_free(&out); 1178 return ret; 1179 } 1180 1181 void 1182 mux_exit_message(Channel *c, int exitval) 1183 { 1184 Buffer m; 1185 Channel *mux_chan; 1186 1187 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1188 exitval); 1189 1190 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1191 fatal("%s: channel %d missing mux channel %d", 1192 __func__, c->self, c->ctl_chan); 1193 1194 /* Append exit message packet to control socket output queue */ 1195 buffer_init(&m); 1196 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1197 buffer_put_int(&m, c->self); 1198 buffer_put_int(&m, exitval); 1199 1200 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1201 buffer_free(&m); 1202 } 1203 1204 void 1205 mux_tty_alloc_failed(Channel *c) 1206 { 1207 Buffer m; 1208 Channel *mux_chan; 1209 1210 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1211 1212 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1213 fatal("%s: channel %d missing mux channel %d", 1214 __func__, c->self, c->ctl_chan); 1215 1216 /* Append exit message packet to control socket output queue */ 1217 buffer_init(&m); 1218 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1219 buffer_put_int(&m, c->self); 1220 1221 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1222 buffer_free(&m); 1223 } 1224 1225 /* Prepare a mux master to listen on a Unix domain socket. */ 1226 void 1227 muxserver_listen(void) 1228 { 1229 mode_t old_umask; 1230 char *orig_control_path = options.control_path; 1231 char rbuf[16+1]; 1232 u_int i, r; 1233 int oerrno; 1234 1235 if (options.control_path == NULL || 1236 options.control_master == SSHCTL_MASTER_NO) 1237 return; 1238 1239 debug("setting up multiplex master socket"); 1240 1241 /* 1242 * Use a temporary path before listen so we can pseudo-atomically 1243 * establish the listening socket in its final location to avoid 1244 * other processes racing in between bind() and listen() and hitting 1245 * an unready socket. 1246 */ 1247 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1248 r = arc4random_uniform(26+26+10); 1249 rbuf[i] = (r < 26) ? 'a' + r : 1250 (r < 26*2) ? 'A' + r - 26 : 1251 '0' + r - 26 - 26; 1252 } 1253 rbuf[sizeof(rbuf) - 1] = '\0'; 1254 options.control_path = NULL; 1255 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1256 debug3("%s: temporary control path %s", __func__, options.control_path); 1257 1258 old_umask = umask(0177); 1259 muxserver_sock = unix_listener(options.control_path, 64, 0); 1260 oerrno = errno; 1261 umask(old_umask); 1262 if (muxserver_sock < 0) { 1263 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1264 error("ControlSocket %s already exists, " 1265 "disabling multiplexing", options.control_path); 1266 disable_mux_master: 1267 if (muxserver_sock != -1) { 1268 close(muxserver_sock); 1269 muxserver_sock = -1; 1270 } 1271 free(orig_control_path); 1272 free(options.control_path); 1273 options.control_path = NULL; 1274 options.control_master = SSHCTL_MASTER_NO; 1275 return; 1276 } else { 1277 /* unix_listener() logs the error */ 1278 cleanup_exit(255); 1279 } 1280 } 1281 1282 /* Now atomically "move" the mux socket into position */ 1283 if (link(options.control_path, orig_control_path) != 0) { 1284 if (errno != EEXIST) { 1285 fatal("%s: link mux listener %s => %s: %s", __func__, 1286 options.control_path, orig_control_path, 1287 strerror(errno)); 1288 } 1289 error("ControlSocket %s already exists, disabling multiplexing", 1290 orig_control_path); 1291 unlink(options.control_path); 1292 goto disable_mux_master; 1293 } 1294 unlink(options.control_path); 1295 free(options.control_path); 1296 options.control_path = orig_control_path; 1297 1298 set_nonblock(muxserver_sock); 1299 1300 mux_listener_channel = channel_new("mux listener", 1301 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1302 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1303 0, options.control_path, 1); 1304 mux_listener_channel->mux_rcb = mux_master_read_cb; 1305 debug3("%s: mux listener channel %d fd %d", __func__, 1306 mux_listener_channel->self, mux_listener_channel->sock); 1307 } 1308 1309 /* Callback on open confirmation in mux master for a mux client session. */ 1310 static void 1311 mux_session_confirm(int id, int success, void *arg) 1312 { 1313 struct mux_session_confirm_ctx *cctx = arg; 1314 const char *display; 1315 Channel *c, *cc; 1316 int i; 1317 Buffer reply; 1318 1319 if (cctx == NULL) 1320 fatal("%s: cctx == NULL", __func__); 1321 if ((c = channel_by_id(id)) == NULL) 1322 fatal("%s: no channel for id %d", __func__, id); 1323 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1324 fatal("%s: channel %d lacks control channel %d", __func__, 1325 id, c->ctl_chan); 1326 1327 if (!success) { 1328 debug3("%s: sending failure reply", __func__); 1329 /* prepare reply */ 1330 buffer_init(&reply); 1331 buffer_put_int(&reply, MUX_S_FAILURE); 1332 buffer_put_int(&reply, cctx->rid); 1333 buffer_put_cstring(&reply, "Session open refused by peer"); 1334 goto done; 1335 } 1336 1337 display = getenv("DISPLAY"); 1338 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1339 char *proto, *data; 1340 1341 /* Get reasonable local authentication information. */ 1342 if (client_x11_get_proto(display, options.xauth_location, 1343 options.forward_x11_trusted, options.forward_x11_timeout, 1344 &proto, &data) == 0) { 1345 /* Request forwarding with authentication spoofing. */ 1346 debug("Requesting X11 forwarding with authentication " 1347 "spoofing."); 1348 x11_request_forwarding_with_spoofing(id, display, proto, 1349 data, 1); 1350 /* XXX exit_on_forward_failure */ 1351 client_expect_confirm(id, "X11 forwarding", 1352 CONFIRM_WARN); 1353 } 1354 } 1355 1356 if (cctx->want_agent_fwd && options.forward_agent) { 1357 debug("Requesting authentication agent forwarding."); 1358 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1359 packet_send(); 1360 } 1361 1362 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1363 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1364 1365 debug3("%s: sending success reply", __func__); 1366 /* prepare reply */ 1367 buffer_init(&reply); 1368 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1369 buffer_put_int(&reply, cctx->rid); 1370 buffer_put_int(&reply, c->self); 1371 1372 done: 1373 /* Send reply */ 1374 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1375 buffer_free(&reply); 1376 1377 if (cc->mux_pause <= 0) 1378 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1379 cc->mux_pause = 0; /* start processing messages again */ 1380 c->open_confirm_ctx = NULL; 1381 buffer_free(&cctx->cmd); 1382 free(cctx->term); 1383 if (cctx->env != NULL) { 1384 for (i = 0; cctx->env[i] != NULL; i++) 1385 free(cctx->env[i]); 1386 free(cctx->env); 1387 } 1388 free(cctx); 1389 } 1390 1391 /* ** Multiplexing client support */ 1392 1393 /* Exit signal handler */ 1394 static void 1395 control_client_sighandler(int signo) 1396 { 1397 muxclient_terminate = signo; 1398 } 1399 1400 /* 1401 * Relay signal handler - used to pass some signals from mux client to 1402 * mux master. 1403 */ 1404 static void 1405 control_client_sigrelay(int signo) 1406 { 1407 int save_errno = errno; 1408 1409 if (muxserver_pid > 1) 1410 kill(muxserver_pid, signo); 1411 1412 errno = save_errno; 1413 } 1414 1415 static int 1416 mux_client_read(int fd, Buffer *b, u_int need) 1417 { 1418 u_int have; 1419 ssize_t len; 1420 u_char *p; 1421 struct pollfd pfd; 1422 1423 pfd.fd = fd; 1424 pfd.events = POLLIN; 1425 p = buffer_append_space(b, need); 1426 for (have = 0; have < need; ) { 1427 if (muxclient_terminate) { 1428 errno = EINTR; 1429 return -1; 1430 } 1431 len = read(fd, p + have, need - have); 1432 if (len < 0) { 1433 switch (errno) { 1434 case EAGAIN: 1435 (void)poll(&pfd, 1, -1); 1436 /* FALLTHROUGH */ 1437 case EINTR: 1438 continue; 1439 default: 1440 return -1; 1441 } 1442 } 1443 if (len == 0) { 1444 errno = EPIPE; 1445 return -1; 1446 } 1447 have += (u_int)len; 1448 } 1449 return 0; 1450 } 1451 1452 static int 1453 mux_client_write_packet(int fd, Buffer *m) 1454 { 1455 Buffer queue; 1456 u_int have, need; 1457 int oerrno, len; 1458 u_char *ptr; 1459 struct pollfd pfd; 1460 1461 pfd.fd = fd; 1462 pfd.events = POLLOUT; 1463 buffer_init(&queue); 1464 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1465 1466 need = buffer_len(&queue); 1467 ptr = buffer_ptr(&queue); 1468 1469 for (have = 0; have < need; ) { 1470 if (muxclient_terminate) { 1471 buffer_free(&queue); 1472 errno = EINTR; 1473 return -1; 1474 } 1475 len = write(fd, ptr + have, need - have); 1476 if (len < 0) { 1477 switch (errno) { 1478 case EAGAIN: 1479 (void)poll(&pfd, 1, -1); 1480 /* FALLTHROUGH */ 1481 case EINTR: 1482 continue; 1483 default: 1484 oerrno = errno; 1485 buffer_free(&queue); 1486 errno = oerrno; 1487 return -1; 1488 } 1489 } 1490 if (len == 0) { 1491 buffer_free(&queue); 1492 errno = EPIPE; 1493 return -1; 1494 } 1495 have += (u_int)len; 1496 } 1497 buffer_free(&queue); 1498 return 0; 1499 } 1500 1501 static int 1502 mux_client_read_packet(int fd, Buffer *m) 1503 { 1504 Buffer queue; 1505 u_int need, have; 1506 const u_char *ptr; 1507 int oerrno; 1508 1509 buffer_init(&queue); 1510 if (mux_client_read(fd, &queue, 4) != 0) { 1511 if ((oerrno = errno) == EPIPE) 1512 debug3("%s: read header failed: %s", __func__, 1513 strerror(errno)); 1514 buffer_free(&queue); 1515 errno = oerrno; 1516 return -1; 1517 } 1518 need = get_u32(buffer_ptr(&queue)); 1519 if (mux_client_read(fd, &queue, need) != 0) { 1520 oerrno = errno; 1521 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1522 buffer_free(&queue); 1523 errno = oerrno; 1524 return -1; 1525 } 1526 ptr = buffer_get_string_ptr(&queue, &have); 1527 buffer_append(m, ptr, have); 1528 buffer_free(&queue); 1529 return 0; 1530 } 1531 1532 static int 1533 mux_client_hello_exchange(int fd) 1534 { 1535 Buffer m; 1536 u_int type, ver; 1537 1538 buffer_init(&m); 1539 buffer_put_int(&m, MUX_MSG_HELLO); 1540 buffer_put_int(&m, SSHMUX_VER); 1541 /* no extensions */ 1542 1543 if (mux_client_write_packet(fd, &m) != 0) 1544 fatal("%s: write packet: %s", __func__, strerror(errno)); 1545 1546 buffer_clear(&m); 1547 1548 /* Read their HELLO */ 1549 if (mux_client_read_packet(fd, &m) != 0) { 1550 buffer_free(&m); 1551 return -1; 1552 } 1553 1554 type = buffer_get_int(&m); 1555 if (type != MUX_MSG_HELLO) 1556 fatal("%s: expected HELLO (%u) received %u", 1557 __func__, MUX_MSG_HELLO, type); 1558 ver = buffer_get_int(&m); 1559 if (ver != SSHMUX_VER) 1560 fatal("Unsupported multiplexing protocol version %d " 1561 "(expected %d)", ver, SSHMUX_VER); 1562 debug2("%s: master version %u", __func__, ver); 1563 /* No extensions are presently defined */ 1564 while (buffer_len(&m) > 0) { 1565 char *name = buffer_get_string(&m, NULL); 1566 char *value = buffer_get_string(&m, NULL); 1567 1568 debug2("Unrecognised master extension \"%s\"", name); 1569 free(name); 1570 free(value); 1571 } 1572 buffer_free(&m); 1573 return 0; 1574 } 1575 1576 static u_int 1577 mux_client_request_alive(int fd) 1578 { 1579 Buffer m; 1580 char *e; 1581 u_int pid, type, rid; 1582 1583 debug3("%s: entering", __func__); 1584 1585 buffer_init(&m); 1586 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1587 buffer_put_int(&m, muxclient_request_id); 1588 1589 if (mux_client_write_packet(fd, &m) != 0) 1590 fatal("%s: write packet: %s", __func__, strerror(errno)); 1591 1592 buffer_clear(&m); 1593 1594 /* Read their reply */ 1595 if (mux_client_read_packet(fd, &m) != 0) { 1596 buffer_free(&m); 1597 return 0; 1598 } 1599 1600 type = buffer_get_int(&m); 1601 if (type != MUX_S_ALIVE) { 1602 e = buffer_get_string(&m, NULL); 1603 fatal("%s: master returned error: %s", __func__, e); 1604 } 1605 1606 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1607 fatal("%s: out of sequence reply: my id %u theirs %u", 1608 __func__, muxclient_request_id, rid); 1609 pid = buffer_get_int(&m); 1610 buffer_free(&m); 1611 1612 debug3("%s: done pid = %u", __func__, pid); 1613 1614 muxclient_request_id++; 1615 1616 return pid; 1617 } 1618 1619 static void 1620 mux_client_request_terminate(int fd) 1621 { 1622 Buffer m; 1623 char *e; 1624 u_int type, rid; 1625 1626 debug3("%s: entering", __func__); 1627 1628 buffer_init(&m); 1629 buffer_put_int(&m, MUX_C_TERMINATE); 1630 buffer_put_int(&m, muxclient_request_id); 1631 1632 if (mux_client_write_packet(fd, &m) != 0) 1633 fatal("%s: write packet: %s", __func__, strerror(errno)); 1634 1635 buffer_clear(&m); 1636 1637 /* Read their reply */ 1638 if (mux_client_read_packet(fd, &m) != 0) { 1639 /* Remote end exited already */ 1640 if (errno == EPIPE) { 1641 buffer_free(&m); 1642 return; 1643 } 1644 fatal("%s: read from master failed: %s", 1645 __func__, strerror(errno)); 1646 } 1647 1648 type = buffer_get_int(&m); 1649 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1650 fatal("%s: out of sequence reply: my id %u theirs %u", 1651 __func__, muxclient_request_id, rid); 1652 switch (type) { 1653 case MUX_S_OK: 1654 break; 1655 case MUX_S_PERMISSION_DENIED: 1656 e = buffer_get_string(&m, NULL); 1657 fatal("Master refused termination request: %s", e); 1658 case MUX_S_FAILURE: 1659 e = buffer_get_string(&m, NULL); 1660 fatal("%s: termination request failed: %s", __func__, e); 1661 default: 1662 fatal("%s: unexpected response from master 0x%08x", 1663 __func__, type); 1664 } 1665 buffer_free(&m); 1666 muxclient_request_id++; 1667 } 1668 1669 static int 1670 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1671 { 1672 Buffer m; 1673 char *e, *fwd_desc; 1674 u_int type, rid; 1675 1676 fwd_desc = format_forward(ftype, fwd); 1677 debug("Requesting %s %s", 1678 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1679 free(fwd_desc); 1680 1681 buffer_init(&m); 1682 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1683 buffer_put_int(&m, muxclient_request_id); 1684 buffer_put_int(&m, ftype); 1685 if (fwd->listen_path != NULL) { 1686 buffer_put_cstring(&m, fwd->listen_path); 1687 } else { 1688 buffer_put_cstring(&m, 1689 fwd->listen_host == NULL ? "" : 1690 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1691 } 1692 buffer_put_int(&m, fwd->listen_port); 1693 if (fwd->connect_path != NULL) { 1694 buffer_put_cstring(&m, fwd->connect_path); 1695 } else { 1696 buffer_put_cstring(&m, 1697 fwd->connect_host == NULL ? "" : fwd->connect_host); 1698 } 1699 buffer_put_int(&m, fwd->connect_port); 1700 1701 if (mux_client_write_packet(fd, &m) != 0) 1702 fatal("%s: write packet: %s", __func__, strerror(errno)); 1703 1704 buffer_clear(&m); 1705 1706 /* Read their reply */ 1707 if (mux_client_read_packet(fd, &m) != 0) { 1708 buffer_free(&m); 1709 return -1; 1710 } 1711 1712 type = buffer_get_int(&m); 1713 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1714 fatal("%s: out of sequence reply: my id %u theirs %u", 1715 __func__, muxclient_request_id, rid); 1716 switch (type) { 1717 case MUX_S_OK: 1718 break; 1719 case MUX_S_REMOTE_PORT: 1720 if (cancel_flag) 1721 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1722 fwd->allocated_port = buffer_get_int(&m); 1723 verbose("Allocated port %u for remote forward to %s:%d", 1724 fwd->allocated_port, 1725 fwd->connect_host ? fwd->connect_host : "", 1726 fwd->connect_port); 1727 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1728 fprintf(stdout, "%i\n", fwd->allocated_port); 1729 break; 1730 case MUX_S_PERMISSION_DENIED: 1731 e = buffer_get_string(&m, NULL); 1732 buffer_free(&m); 1733 error("Master refused forwarding request: %s", e); 1734 return -1; 1735 case MUX_S_FAILURE: 1736 e = buffer_get_string(&m, NULL); 1737 buffer_free(&m); 1738 error("%s: forwarding request failed: %s", __func__, e); 1739 return -1; 1740 default: 1741 fatal("%s: unexpected response from master 0x%08x", 1742 __func__, type); 1743 } 1744 buffer_free(&m); 1745 1746 muxclient_request_id++; 1747 return 0; 1748 } 1749 1750 static int 1751 mux_client_forwards(int fd, int cancel_flag) 1752 { 1753 int i, ret = 0; 1754 1755 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1756 cancel_flag ? "cancel" : "request", 1757 options.num_local_forwards, options.num_remote_forwards); 1758 1759 /* XXX ExitOnForwardingFailure */ 1760 for (i = 0; i < options.num_local_forwards; i++) { 1761 if (mux_client_forward(fd, cancel_flag, 1762 options.local_forwards[i].connect_port == 0 ? 1763 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1764 options.local_forwards + i) != 0) 1765 ret = -1; 1766 } 1767 for (i = 0; i < options.num_remote_forwards; i++) { 1768 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1769 options.remote_forwards + i) != 0) 1770 ret = -1; 1771 } 1772 return ret; 1773 } 1774 1775 static int 1776 mux_client_request_session(int fd) 1777 { 1778 Buffer m; 1779 char *e, *term; 1780 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1781 extern char **environ; 1782 int devnull, rawmode; 1783 1784 debug3("%s: entering", __func__); 1785 1786 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1787 error("%s: master alive request failed", __func__); 1788 return -1; 1789 } 1790 1791 signal(SIGPIPE, SIG_IGN); 1792 1793 if (stdin_null_flag) { 1794 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1795 fatal("open(/dev/null): %s", strerror(errno)); 1796 if (dup2(devnull, STDIN_FILENO) == -1) 1797 fatal("dup2: %s", strerror(errno)); 1798 if (devnull > STDERR_FILENO) 1799 close(devnull); 1800 } 1801 1802 term = getenv("TERM"); 1803 1804 buffer_init(&m); 1805 buffer_put_int(&m, MUX_C_NEW_SESSION); 1806 buffer_put_int(&m, muxclient_request_id); 1807 buffer_put_cstring(&m, ""); /* reserved */ 1808 buffer_put_int(&m, tty_flag); 1809 buffer_put_int(&m, options.forward_x11); 1810 buffer_put_int(&m, options.forward_agent); 1811 buffer_put_int(&m, subsystem_flag); 1812 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1813 0xffffffff : (u_int)options.escape_char); 1814 buffer_put_cstring(&m, term == NULL ? "" : term); 1815 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1816 1817 if (options.num_send_env > 0 && environ != NULL) { 1818 /* Pass environment */ 1819 for (i = 0; environ[i] != NULL; i++) { 1820 if (env_permitted(environ[i])) { 1821 buffer_put_cstring(&m, environ[i]); 1822 } 1823 } 1824 } 1825 1826 if (mux_client_write_packet(fd, &m) != 0) 1827 fatal("%s: write packet: %s", __func__, strerror(errno)); 1828 1829 /* Send the stdio file descriptors */ 1830 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1831 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1832 mm_send_fd(fd, STDERR_FILENO) == -1) 1833 fatal("%s: send fds failed", __func__); 1834 1835 debug3("%s: session request sent", __func__); 1836 1837 /* Read their reply */ 1838 buffer_clear(&m); 1839 if (mux_client_read_packet(fd, &m) != 0) { 1840 error("%s: read from master failed: %s", 1841 __func__, strerror(errno)); 1842 buffer_free(&m); 1843 return -1; 1844 } 1845 1846 type = buffer_get_int(&m); 1847 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1848 fatal("%s: out of sequence reply: my id %u theirs %u", 1849 __func__, muxclient_request_id, rid); 1850 switch (type) { 1851 case MUX_S_SESSION_OPENED: 1852 sid = buffer_get_int(&m); 1853 debug("%s: master session id: %u", __func__, sid); 1854 break; 1855 case MUX_S_PERMISSION_DENIED: 1856 e = buffer_get_string(&m, NULL); 1857 buffer_free(&m); 1858 error("Master refused session request: %s", e); 1859 return -1; 1860 case MUX_S_FAILURE: 1861 e = buffer_get_string(&m, NULL); 1862 buffer_free(&m); 1863 error("%s: session request failed: %s", __func__, e); 1864 return -1; 1865 default: 1866 buffer_free(&m); 1867 error("%s: unexpected response from master 0x%08x", 1868 __func__, type); 1869 return -1; 1870 } 1871 muxclient_request_id++; 1872 1873 if (pledge("stdio proc tty", NULL) == -1) 1874 fatal("%s pledge(): %s", __func__, strerror(errno)); 1875 1876 signal(SIGHUP, control_client_sighandler); 1877 signal(SIGINT, control_client_sighandler); 1878 signal(SIGTERM, control_client_sighandler); 1879 signal(SIGWINCH, control_client_sigrelay); 1880 1881 rawmode = tty_flag; 1882 if (tty_flag) 1883 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1884 1885 /* 1886 * Stick around until the controlee closes the client_fd. 1887 * Before it does, it is expected to write an exit message. 1888 * This process must read the value and wait for the closure of 1889 * the client_fd; if this one closes early, the multiplex master will 1890 * terminate early too (possibly losing data). 1891 */ 1892 for (exitval = 255, exitval_seen = 0;;) { 1893 buffer_clear(&m); 1894 if (mux_client_read_packet(fd, &m) != 0) 1895 break; 1896 type = buffer_get_int(&m); 1897 switch (type) { 1898 case MUX_S_TTY_ALLOC_FAIL: 1899 if ((esid = buffer_get_int(&m)) != sid) 1900 fatal("%s: tty alloc fail on unknown session: " 1901 "my id %u theirs %u", 1902 __func__, sid, esid); 1903 leave_raw_mode(options.request_tty == 1904 REQUEST_TTY_FORCE); 1905 rawmode = 0; 1906 continue; 1907 case MUX_S_EXIT_MESSAGE: 1908 if ((esid = buffer_get_int(&m)) != sid) 1909 fatal("%s: exit on unknown session: " 1910 "my id %u theirs %u", 1911 __func__, sid, esid); 1912 if (exitval_seen) 1913 fatal("%s: exitval sent twice", __func__); 1914 exitval = buffer_get_int(&m); 1915 exitval_seen = 1; 1916 continue; 1917 default: 1918 e = buffer_get_string(&m, NULL); 1919 fatal("%s: master returned error: %s", __func__, e); 1920 } 1921 } 1922 1923 close(fd); 1924 if (rawmode) 1925 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1926 1927 if (muxclient_terminate) { 1928 debug2("Exiting on signal %d", muxclient_terminate); 1929 exitval = 255; 1930 } else if (!exitval_seen) { 1931 debug2("Control master terminated unexpectedly"); 1932 exitval = 255; 1933 } else 1934 debug2("Received exit status from master %d", exitval); 1935 1936 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1937 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1938 1939 exit(exitval); 1940 } 1941 1942 static int 1943 mux_client_request_stdio_fwd(int fd) 1944 { 1945 Buffer m; 1946 char *e; 1947 u_int type, rid, sid; 1948 int devnull; 1949 1950 debug3("%s: entering", __func__); 1951 1952 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1953 error("%s: master alive request failed", __func__); 1954 return -1; 1955 } 1956 1957 signal(SIGPIPE, SIG_IGN); 1958 1959 if (stdin_null_flag) { 1960 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1961 fatal("open(/dev/null): %s", strerror(errno)); 1962 if (dup2(devnull, STDIN_FILENO) == -1) 1963 fatal("dup2: %s", strerror(errno)); 1964 if (devnull > STDERR_FILENO) 1965 close(devnull); 1966 } 1967 1968 buffer_init(&m); 1969 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1970 buffer_put_int(&m, muxclient_request_id); 1971 buffer_put_cstring(&m, ""); /* reserved */ 1972 buffer_put_cstring(&m, options.stdio_forward_host); 1973 buffer_put_int(&m, options.stdio_forward_port); 1974 1975 if (mux_client_write_packet(fd, &m) != 0) 1976 fatal("%s: write packet: %s", __func__, strerror(errno)); 1977 1978 /* Send the stdio file descriptors */ 1979 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1980 mm_send_fd(fd, STDOUT_FILENO) == -1) 1981 fatal("%s: send fds failed", __func__); 1982 1983 if (pledge("stdio proc tty", NULL) == -1) 1984 fatal("%s pledge(): %s", __func__, strerror(errno)); 1985 1986 debug3("%s: stdio forward request sent", __func__); 1987 1988 /* Read their reply */ 1989 buffer_clear(&m); 1990 1991 if (mux_client_read_packet(fd, &m) != 0) { 1992 error("%s: read from master failed: %s", 1993 __func__, strerror(errno)); 1994 buffer_free(&m); 1995 return -1; 1996 } 1997 1998 type = buffer_get_int(&m); 1999 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2000 fatal("%s: out of sequence reply: my id %u theirs %u", 2001 __func__, muxclient_request_id, rid); 2002 switch (type) { 2003 case MUX_S_SESSION_OPENED: 2004 sid = buffer_get_int(&m); 2005 debug("%s: master session id: %u", __func__, sid); 2006 break; 2007 case MUX_S_PERMISSION_DENIED: 2008 e = buffer_get_string(&m, NULL); 2009 buffer_free(&m); 2010 fatal("Master refused stdio forwarding request: %s", e); 2011 case MUX_S_FAILURE: 2012 e = buffer_get_string(&m, NULL); 2013 buffer_free(&m); 2014 fatal("Stdio forwarding request failed: %s", e); 2015 default: 2016 buffer_free(&m); 2017 error("%s: unexpected response from master 0x%08x", 2018 __func__, type); 2019 return -1; 2020 } 2021 muxclient_request_id++; 2022 2023 signal(SIGHUP, control_client_sighandler); 2024 signal(SIGINT, control_client_sighandler); 2025 signal(SIGTERM, control_client_sighandler); 2026 signal(SIGWINCH, control_client_sigrelay); 2027 2028 /* 2029 * Stick around until the controlee closes the client_fd. 2030 */ 2031 buffer_clear(&m); 2032 if (mux_client_read_packet(fd, &m) != 0) { 2033 if (errno == EPIPE || 2034 (errno == EINTR && muxclient_terminate != 0)) 2035 return 0; 2036 fatal("%s: mux_client_read_packet: %s", 2037 __func__, strerror(errno)); 2038 } 2039 fatal("%s: master returned unexpected message %u", __func__, type); 2040 } 2041 2042 static void 2043 mux_client_request_stop_listening(int fd) 2044 { 2045 Buffer m; 2046 char *e; 2047 u_int type, rid; 2048 2049 debug3("%s: entering", __func__); 2050 2051 buffer_init(&m); 2052 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2053 buffer_put_int(&m, muxclient_request_id); 2054 2055 if (mux_client_write_packet(fd, &m) != 0) 2056 fatal("%s: write packet: %s", __func__, strerror(errno)); 2057 2058 buffer_clear(&m); 2059 2060 /* Read their reply */ 2061 if (mux_client_read_packet(fd, &m) != 0) 2062 fatal("%s: read from master failed: %s", 2063 __func__, strerror(errno)); 2064 2065 type = buffer_get_int(&m); 2066 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2067 fatal("%s: out of sequence reply: my id %u theirs %u", 2068 __func__, muxclient_request_id, rid); 2069 switch (type) { 2070 case MUX_S_OK: 2071 break; 2072 case MUX_S_PERMISSION_DENIED: 2073 e = buffer_get_string(&m, NULL); 2074 fatal("Master refused stop listening request: %s", e); 2075 case MUX_S_FAILURE: 2076 e = buffer_get_string(&m, NULL); 2077 fatal("%s: stop listening request failed: %s", __func__, e); 2078 default: 2079 fatal("%s: unexpected response from master 0x%08x", 2080 __func__, type); 2081 } 2082 buffer_free(&m); 2083 muxclient_request_id++; 2084 } 2085 2086 /* Multiplex client main loop. */ 2087 void 2088 muxclient(const char *path) 2089 { 2090 struct sockaddr_un addr; 2091 int sock; 2092 u_int pid; 2093 2094 if (muxclient_command == 0) { 2095 if (options.stdio_forward_host != NULL) 2096 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2097 else 2098 muxclient_command = SSHMUX_COMMAND_OPEN; 2099 } 2100 2101 switch (options.control_master) { 2102 case SSHCTL_MASTER_AUTO: 2103 case SSHCTL_MASTER_AUTO_ASK: 2104 debug("auto-mux: Trying existing master"); 2105 /* FALLTHROUGH */ 2106 case SSHCTL_MASTER_NO: 2107 break; 2108 default: 2109 return; 2110 } 2111 2112 memset(&addr, '\0', sizeof(addr)); 2113 addr.sun_family = AF_UNIX; 2114 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 2115 strlen(path) + 1; 2116 2117 if (strlcpy(addr.sun_path, path, 2118 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2119 fatal("ControlPath too long"); 2120 2121 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2122 fatal("%s socket(): %s", __func__, strerror(errno)); 2123 2124 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 2125 switch (muxclient_command) { 2126 case SSHMUX_COMMAND_OPEN: 2127 case SSHMUX_COMMAND_STDIO_FWD: 2128 break; 2129 default: 2130 fatal("Control socket connect(%.100s): %s", path, 2131 strerror(errno)); 2132 } 2133 if (errno == ECONNREFUSED && 2134 options.control_master != SSHCTL_MASTER_NO) { 2135 debug("Stale control socket %.100s, unlinking", path); 2136 unlink(path); 2137 } else if (errno == ENOENT) { 2138 debug("Control socket \"%.100s\" does not exist", path); 2139 } else { 2140 error("Control socket connect(%.100s): %s", path, 2141 strerror(errno)); 2142 } 2143 close(sock); 2144 return; 2145 } 2146 set_nonblock(sock); 2147 2148 if (mux_client_hello_exchange(sock) != 0) { 2149 error("%s: master hello exchange failed", __func__); 2150 close(sock); 2151 return; 2152 } 2153 2154 switch (muxclient_command) { 2155 case SSHMUX_COMMAND_ALIVE_CHECK: 2156 if ((pid = mux_client_request_alive(sock)) == 0) 2157 fatal("%s: master alive check failed", __func__); 2158 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2159 exit(0); 2160 case SSHMUX_COMMAND_TERMINATE: 2161 mux_client_request_terminate(sock); 2162 fprintf(stderr, "Exit request sent.\r\n"); 2163 exit(0); 2164 case SSHMUX_COMMAND_FORWARD: 2165 if (mux_client_forwards(sock, 0) != 0) 2166 fatal("%s: master forward request failed", __func__); 2167 exit(0); 2168 case SSHMUX_COMMAND_OPEN: 2169 if (mux_client_forwards(sock, 0) != 0) { 2170 error("%s: master forward request failed", __func__); 2171 return; 2172 } 2173 mux_client_request_session(sock); 2174 return; 2175 case SSHMUX_COMMAND_STDIO_FWD: 2176 mux_client_request_stdio_fwd(sock); 2177 exit(0); 2178 case SSHMUX_COMMAND_STOP: 2179 mux_client_request_stop_listening(sock); 2180 fprintf(stderr, "Stop listening request sent.\r\n"); 2181 exit(0); 2182 case SSHMUX_COMMAND_CANCEL_FWD: 2183 if (mux_client_forwards(sock, 1) != 0) 2184 error("%s: master cancel forward request failed", 2185 __func__); 2186 exit(0); 2187 default: 2188 fatal("unrecognised muxclient_command %d", muxclient_command); 2189 } 2190 } 2191