1 /* $OpenBSD: mux.c,v 1.64 2017/01/21 11:32:04 guenther Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm (at) openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 /* 21 * TODO: 22 * - Better signalling from master to slave, especially passing of 23 * error messages 24 * - Better fall-back from mux slave error to new connection. 25 * - ExitOnForwardingFailure 26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 27 * - Support ~^Z in mux slaves. 28 * - Inspect or control sessions in master. 29 * - If we ever support the "signal" channel request, send signals on 30 * sessions in master. 31 */ 32 33 #include "includes.h" 34 35 #include <sys/types.h> 36 #include <sys/stat.h> 37 #include <sys/socket.h> 38 #include <sys/un.h> 39 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <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 #ifdef HAVE_PATHS_H 50 #include <paths.h> 51 #endif 52 53 #ifdef HAVE_POLL_H 54 #include <poll.h> 55 #else 56 # ifdef HAVE_SYS_POLL_H 57 # include <sys/poll.h> 58 # endif 59 #endif 60 61 #ifdef HAVE_UTIL_H 62 # include <util.h> 63 #endif 64 65 #include "openbsd-compat/sys-queue.h" 66 #include "xmalloc.h" 67 #include "log.h" 68 #include "ssh.h" 69 #include "ssh2.h" 70 #include "pathnames.h" 71 #include "misc.h" 72 #include "match.h" 73 #include "buffer.h" 74 #include "channels.h" 75 #include "msg.h" 76 #include "packet.h" 77 #include "monitor_fdpass.h" 78 #include "sshpty.h" 79 #include "key.h" 80 #include "readconf.h" 81 #include "clientloop.h" 82 #include "ssherr.h" 83 84 /* from ssh.c */ 85 extern int tty_flag; 86 extern Options options; 87 extern int stdin_null_flag; 88 extern char *host; 89 extern int subsystem_flag; 90 extern Buffer command; 91 extern volatile sig_atomic_t quit_pending; 92 93 /* Context for session open confirmation callback */ 94 struct mux_session_confirm_ctx { 95 u_int want_tty; 96 u_int want_subsys; 97 u_int want_x_fwd; 98 u_int want_agent_fwd; 99 Buffer cmd; 100 char *term; 101 struct termios tio; 102 char **env; 103 u_int rid; 104 }; 105 106 /* Context for stdio fwd open confirmation callback */ 107 struct mux_stdio_confirm_ctx { 108 u_int rid; 109 }; 110 111 /* Context for global channel callback */ 112 struct mux_channel_confirm_ctx { 113 u_int cid; /* channel id */ 114 u_int rid; /* request id */ 115 int fid; /* forward id */ 116 }; 117 118 /* fd to control socket */ 119 int muxserver_sock = -1; 120 121 /* client request id */ 122 u_int muxclient_request_id = 0; 123 124 /* Multiplexing control command */ 125 u_int muxclient_command = 0; 126 127 /* Set when signalled. */ 128 static volatile sig_atomic_t muxclient_terminate = 0; 129 130 /* PID of multiplex server */ 131 static u_int muxserver_pid = 0; 132 133 static Channel *mux_listener_channel = NULL; 134 135 struct mux_master_state { 136 int hello_rcvd; 137 }; 138 139 /* mux protocol messages */ 140 #define MUX_MSG_HELLO 0x00000001 141 #define MUX_C_NEW_SESSION 0x10000002 142 #define MUX_C_ALIVE_CHECK 0x10000004 143 #define MUX_C_TERMINATE 0x10000005 144 #define MUX_C_OPEN_FWD 0x10000006 145 #define MUX_C_CLOSE_FWD 0x10000007 146 #define MUX_C_NEW_STDIO_FWD 0x10000008 147 #define MUX_C_STOP_LISTENING 0x10000009 148 #define MUX_C_PROXY 0x1000000f 149 #define MUX_S_OK 0x80000001 150 #define MUX_S_PERMISSION_DENIED 0x80000002 151 #define MUX_S_FAILURE 0x80000003 152 #define MUX_S_EXIT_MESSAGE 0x80000004 153 #define MUX_S_ALIVE 0x80000005 154 #define MUX_S_SESSION_OPENED 0x80000006 155 #define MUX_S_REMOTE_PORT 0x80000007 156 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 157 #define MUX_S_PROXY 0x8000000f 158 159 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 160 #define MUX_FWD_LOCAL 1 161 #define MUX_FWD_REMOTE 2 162 #define MUX_FWD_DYNAMIC 3 163 164 static void mux_session_confirm(int, int, void *); 165 static void mux_stdio_confirm(int, int, void *); 166 167 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 168 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 169 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 170 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 171 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 172 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 173 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 174 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 175 static int process_mux_proxy(u_int, Channel *, Buffer *, Buffer *); 176 177 static const struct { 178 u_int type; 179 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 180 } mux_master_handlers[] = { 181 { MUX_MSG_HELLO, process_mux_master_hello }, 182 { MUX_C_NEW_SESSION, process_mux_new_session }, 183 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 184 { MUX_C_TERMINATE, process_mux_terminate }, 185 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 186 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 187 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 188 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 189 { MUX_C_PROXY, process_mux_proxy }, 190 { 0, NULL } 191 }; 192 193 /* Cleanup callback fired on closure of mux slave _session_ channel */ 194 /* ARGSUSED */ 195 static void 196 mux_master_session_cleanup_cb(int cid, void *unused) 197 { 198 Channel *cc, *c = channel_by_id(cid); 199 200 debug3("%s: entering for channel %d", __func__, cid); 201 if (c == NULL) 202 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 203 if (c->ctl_chan != -1) { 204 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 205 fatal("%s: channel %d missing control channel %d", 206 __func__, c->self, c->ctl_chan); 207 c->ctl_chan = -1; 208 cc->remote_id = -1; 209 chan_rcvd_oclose(cc); 210 } 211 channel_cancel_cleanup(c->self); 212 } 213 214 /* Cleanup callback fired on closure of mux slave _control_ channel */ 215 /* ARGSUSED */ 216 static void 217 mux_master_control_cleanup_cb(int cid, void *unused) 218 { 219 Channel *sc, *c = channel_by_id(cid); 220 221 debug3("%s: entering for channel %d", __func__, cid); 222 if (c == NULL) 223 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 224 if (c->remote_id != -1) { 225 if ((sc = channel_by_id(c->remote_id)) == NULL) 226 fatal("%s: channel %d missing session channel %d", 227 __func__, c->self, c->remote_id); 228 c->remote_id = -1; 229 sc->ctl_chan = -1; 230 if (sc->type != SSH_CHANNEL_OPEN && 231 sc->type != SSH_CHANNEL_OPENING) { 232 debug2("%s: channel %d: not open", __func__, sc->self); 233 chan_mark_dead(sc); 234 } else { 235 if (sc->istate == CHAN_INPUT_OPEN) 236 chan_read_failed(sc); 237 if (sc->ostate == CHAN_OUTPUT_OPEN) 238 chan_write_failed(sc); 239 } 240 } 241 channel_cancel_cleanup(c->self); 242 } 243 244 /* Check mux client environment variables before passing them to mux master. */ 245 static int 246 env_permitted(char *env) 247 { 248 int i, ret; 249 char name[1024], *cp; 250 251 if ((cp = strchr(env, '=')) == NULL || cp == env) 252 return 0; 253 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 254 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 255 error("env_permitted: name '%.100s...' too long", env); 256 return 0; 257 } 258 259 for (i = 0; i < options.num_send_env; i++) 260 if (match_pattern(name, options.send_env[i])) 261 return 1; 262 263 return 0; 264 } 265 266 /* Mux master protocol message handlers */ 267 268 static int 269 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 270 { 271 u_int ver; 272 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 273 274 if (state == NULL) 275 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 276 if (state->hello_rcvd) { 277 error("%s: HELLO received twice", __func__); 278 return -1; 279 } 280 if (buffer_get_int_ret(&ver, m) != 0) { 281 malf: 282 error("%s: malformed message", __func__); 283 return -1; 284 } 285 if (ver != SSHMUX_VER) { 286 error("Unsupported multiplexing protocol version %d " 287 "(expected %d)", ver, SSHMUX_VER); 288 return -1; 289 } 290 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 291 292 /* No extensions are presently defined */ 293 while (buffer_len(m) > 0) { 294 char *name = buffer_get_string_ret(m, NULL); 295 char *value = buffer_get_string_ret(m, NULL); 296 297 if (name == NULL || value == NULL) { 298 free(name); 299 free(value); 300 goto malf; 301 } 302 debug2("Unrecognised slave extension \"%s\"", name); 303 free(name); 304 free(value); 305 } 306 state->hello_rcvd = 1; 307 return 0; 308 } 309 310 static int 311 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 312 { 313 Channel *nc; 314 struct mux_session_confirm_ctx *cctx; 315 char *reserved, *cmd, *cp; 316 u_int i, j, len, env_len, escape_char, window, packetmax; 317 int new_fd[3]; 318 319 /* Reply for SSHMUX_COMMAND_OPEN */ 320 cctx = xcalloc(1, sizeof(*cctx)); 321 cctx->term = NULL; 322 cctx->rid = rid; 323 cmd = reserved = NULL; 324 cctx->env = NULL; 325 env_len = 0; 326 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 327 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 328 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 329 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 330 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 331 buffer_get_int_ret(&escape_char, m) != 0 || 332 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 333 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 334 malf: 335 free(cmd); 336 free(reserved); 337 for (j = 0; j < env_len; j++) 338 free(cctx->env[j]); 339 free(cctx->env); 340 free(cctx->term); 341 free(cctx); 342 error("%s: malformed message", __func__); 343 return -1; 344 } 345 free(reserved); 346 reserved = NULL; 347 348 while (buffer_len(m) > 0) { 349 #define MUX_MAX_ENV_VARS 4096 350 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 351 goto malf; 352 if (!env_permitted(cp)) { 353 free(cp); 354 continue; 355 } 356 cctx->env = xreallocarray(cctx->env, env_len + 2, 357 sizeof(*cctx->env)); 358 cctx->env[env_len++] = cp; 359 cctx->env[env_len] = NULL; 360 if (env_len > MUX_MAX_ENV_VARS) { 361 error(">%d environment variables received, ignoring " 362 "additional", MUX_MAX_ENV_VARS); 363 break; 364 } 365 } 366 367 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 368 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 369 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 370 cctx->want_subsys, cctx->term, cmd, env_len); 371 372 buffer_init(&cctx->cmd); 373 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 374 free(cmd); 375 cmd = NULL; 376 377 /* Gather fds from client */ 378 for(i = 0; i < 3; i++) { 379 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 380 error("%s: failed to receive fd %d from slave", 381 __func__, i); 382 for (j = 0; j < i; j++) 383 close(new_fd[j]); 384 for (j = 0; j < env_len; j++) 385 free(cctx->env[j]); 386 free(cctx->env); 387 free(cctx->term); 388 buffer_free(&cctx->cmd); 389 free(cctx); 390 391 /* prepare reply */ 392 buffer_put_int(r, MUX_S_FAILURE); 393 buffer_put_int(r, rid); 394 buffer_put_cstring(r, 395 "did not receive file descriptors"); 396 return -1; 397 } 398 } 399 400 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 401 new_fd[0], new_fd[1], new_fd[2]); 402 403 /* XXX support multiple child sessions in future */ 404 if (c->remote_id != -1) { 405 debug2("%s: session already open", __func__); 406 /* prepare reply */ 407 buffer_put_int(r, MUX_S_FAILURE); 408 buffer_put_int(r, rid); 409 buffer_put_cstring(r, "Multiple sessions not supported"); 410 cleanup: 411 close(new_fd[0]); 412 close(new_fd[1]); 413 close(new_fd[2]); 414 free(cctx->term); 415 if (env_len != 0) { 416 for (i = 0; i < env_len; i++) 417 free(cctx->env[i]); 418 free(cctx->env); 419 } 420 buffer_free(&cctx->cmd); 421 free(cctx); 422 return 0; 423 } 424 425 if (options.control_master == SSHCTL_MASTER_ASK || 426 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 427 if (!ask_permission("Allow shared connection to %s? ", host)) { 428 debug2("%s: session refused by user", __func__); 429 /* prepare reply */ 430 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 431 buffer_put_int(r, rid); 432 buffer_put_cstring(r, "Permission denied"); 433 goto cleanup; 434 } 435 } 436 437 /* Try to pick up ttymodes from client before it goes raw */ 438 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 439 error("%s: tcgetattr: %s", __func__, strerror(errno)); 440 441 /* enable nonblocking unless tty */ 442 if (!isatty(new_fd[0])) 443 set_nonblock(new_fd[0]); 444 if (!isatty(new_fd[1])) 445 set_nonblock(new_fd[1]); 446 if (!isatty(new_fd[2])) 447 set_nonblock(new_fd[2]); 448 449 window = CHAN_SES_WINDOW_DEFAULT; 450 packetmax = CHAN_SES_PACKET_DEFAULT; 451 if (cctx->want_tty) { 452 window >>= 1; 453 packetmax >>= 1; 454 } 455 456 nc = channel_new("session", SSH_CHANNEL_OPENING, 457 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 458 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 459 460 nc->ctl_chan = c->self; /* link session -> control channel */ 461 c->remote_id = nc->self; /* link control -> session channel */ 462 463 if (cctx->want_tty && escape_char != 0xffffffff) { 464 channel_register_filter(nc->self, 465 client_simple_escape_filter, NULL, 466 client_filter_cleanup, 467 client_new_escape_filter_ctx((int)escape_char)); 468 } 469 470 debug2("%s: channel_new: %d linked to control channel %d", 471 __func__, nc->self, nc->ctl_chan); 472 473 channel_send_open(nc->self); 474 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 475 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 476 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 477 478 /* reply is deferred, sent by mux_session_confirm */ 479 return 0; 480 } 481 482 static int 483 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 484 { 485 debug2("%s: channel %d: alive check", __func__, c->self); 486 487 /* prepare reply */ 488 buffer_put_int(r, MUX_S_ALIVE); 489 buffer_put_int(r, rid); 490 buffer_put_int(r, (u_int)getpid()); 491 492 return 0; 493 } 494 495 static int 496 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 497 { 498 debug2("%s: channel %d: terminate request", __func__, c->self); 499 500 if (options.control_master == SSHCTL_MASTER_ASK || 501 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 502 if (!ask_permission("Terminate shared connection to %s? ", 503 host)) { 504 debug2("%s: termination refused by user", __func__); 505 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 506 buffer_put_int(r, rid); 507 buffer_put_cstring(r, "Permission denied"); 508 return 0; 509 } 510 } 511 512 quit_pending = 1; 513 buffer_put_int(r, MUX_S_OK); 514 buffer_put_int(r, rid); 515 /* XXX exit happens too soon - message never makes it to client */ 516 return 0; 517 } 518 519 static char * 520 format_forward(u_int ftype, struct Forward *fwd) 521 { 522 char *ret; 523 524 switch (ftype) { 525 case MUX_FWD_LOCAL: 526 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 527 (fwd->listen_path != NULL) ? fwd->listen_path : 528 (fwd->listen_host == NULL) ? 529 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 530 fwd->listen_host, fwd->listen_port, 531 (fwd->connect_path != NULL) ? fwd->connect_path : 532 fwd->connect_host, fwd->connect_port); 533 break; 534 case MUX_FWD_DYNAMIC: 535 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 536 (fwd->listen_host == NULL) ? 537 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 538 fwd->listen_host, fwd->listen_port); 539 break; 540 case MUX_FWD_REMOTE: 541 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 542 (fwd->listen_path != NULL) ? fwd->listen_path : 543 (fwd->listen_host == NULL) ? 544 "LOCALHOST" : fwd->listen_host, 545 fwd->listen_port, 546 (fwd->connect_path != NULL) ? fwd->connect_path : 547 fwd->connect_host, fwd->connect_port); 548 break; 549 default: 550 fatal("%s: unknown forward type %u", __func__, ftype); 551 } 552 return ret; 553 } 554 555 static int 556 compare_host(const char *a, const char *b) 557 { 558 if (a == NULL && b == NULL) 559 return 1; 560 if (a == NULL || b == NULL) 561 return 0; 562 return strcmp(a, b) == 0; 563 } 564 565 static int 566 compare_forward(struct Forward *a, struct Forward *b) 567 { 568 if (!compare_host(a->listen_host, b->listen_host)) 569 return 0; 570 if (!compare_host(a->listen_path, b->listen_path)) 571 return 0; 572 if (a->listen_port != b->listen_port) 573 return 0; 574 if (!compare_host(a->connect_host, b->connect_host)) 575 return 0; 576 if (!compare_host(a->connect_path, b->connect_path)) 577 return 0; 578 if (a->connect_port != b->connect_port) 579 return 0; 580 581 return 1; 582 } 583 584 static void 585 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 586 { 587 struct mux_channel_confirm_ctx *fctx = ctxt; 588 char *failmsg = NULL; 589 struct Forward *rfwd; 590 Channel *c; 591 Buffer out; 592 593 if ((c = channel_by_id(fctx->cid)) == NULL) { 594 /* no channel for reply */ 595 error("%s: unknown channel", __func__); 596 return; 597 } 598 buffer_init(&out); 599 if (fctx->fid >= options.num_remote_forwards || 600 (options.remote_forwards[fctx->fid].connect_path == NULL && 601 options.remote_forwards[fctx->fid].connect_host == NULL)) { 602 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 603 goto fail; 604 } 605 rfwd = &options.remote_forwards[fctx->fid]; 606 debug("%s: %s for: listen %d, connect %s:%d", __func__, 607 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 608 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 609 rfwd->connect_host, rfwd->connect_port); 610 if (type == SSH2_MSG_REQUEST_SUCCESS) { 611 if (rfwd->listen_port == 0) { 612 rfwd->allocated_port = packet_get_int(); 613 debug("Allocated port %u for mux remote forward" 614 " to %s:%d", rfwd->allocated_port, 615 rfwd->connect_host, rfwd->connect_port); 616 buffer_put_int(&out, MUX_S_REMOTE_PORT); 617 buffer_put_int(&out, fctx->rid); 618 buffer_put_int(&out, rfwd->allocated_port); 619 channel_update_permitted_opens(rfwd->handle, 620 rfwd->allocated_port); 621 } else { 622 buffer_put_int(&out, MUX_S_OK); 623 buffer_put_int(&out, fctx->rid); 624 } 625 goto out; 626 } else { 627 if (rfwd->listen_port == 0) 628 channel_update_permitted_opens(rfwd->handle, -1); 629 if (rfwd->listen_path != NULL) 630 xasprintf(&failmsg, "remote port forwarding failed for " 631 "listen path %s", rfwd->listen_path); 632 else 633 xasprintf(&failmsg, "remote port forwarding failed for " 634 "listen port %d", rfwd->listen_port); 635 636 debug2("%s: clearing registered forwarding for listen %d, " 637 "connect %s:%d", __func__, rfwd->listen_port, 638 rfwd->connect_path ? rfwd->connect_path : 639 rfwd->connect_host, rfwd->connect_port); 640 641 free(rfwd->listen_host); 642 free(rfwd->listen_path); 643 free(rfwd->connect_host); 644 free(rfwd->connect_path); 645 memset(rfwd, 0, sizeof(*rfwd)); 646 } 647 fail: 648 error("%s: %s", __func__, failmsg); 649 buffer_put_int(&out, MUX_S_FAILURE); 650 buffer_put_int(&out, fctx->rid); 651 buffer_put_cstring(&out, failmsg); 652 free(failmsg); 653 out: 654 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 655 buffer_free(&out); 656 if (c->mux_pause <= 0) 657 fatal("%s: mux_pause %d", __func__, c->mux_pause); 658 c->mux_pause = 0; /* start processing messages again */ 659 } 660 661 static int 662 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 663 { 664 struct Forward fwd; 665 char *fwd_desc = NULL; 666 char *listen_addr, *connect_addr; 667 u_int ftype; 668 u_int lport, cport; 669 int i, ret = 0, freefwd = 1; 670 671 memset(&fwd, 0, sizeof(fwd)); 672 673 /* XXX - lport/cport check redundant */ 674 if (buffer_get_int_ret(&ftype, m) != 0 || 675 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 676 buffer_get_int_ret(&lport, m) != 0 || 677 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 678 buffer_get_int_ret(&cport, m) != 0 || 679 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 680 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 681 error("%s: malformed message", __func__); 682 ret = -1; 683 goto out; 684 } 685 if (*listen_addr == '\0') { 686 free(listen_addr); 687 listen_addr = NULL; 688 } 689 if (*connect_addr == '\0') { 690 free(connect_addr); 691 connect_addr = NULL; 692 } 693 694 memset(&fwd, 0, sizeof(fwd)); 695 fwd.listen_port = lport; 696 if (fwd.listen_port == PORT_STREAMLOCAL) 697 fwd.listen_path = listen_addr; 698 else 699 fwd.listen_host = listen_addr; 700 fwd.connect_port = cport; 701 if (fwd.connect_port == PORT_STREAMLOCAL) 702 fwd.connect_path = connect_addr; 703 else 704 fwd.connect_host = connect_addr; 705 706 debug2("%s: channel %d: request %s", __func__, c->self, 707 (fwd_desc = format_forward(ftype, &fwd))); 708 709 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 710 ftype != MUX_FWD_DYNAMIC) { 711 logit("%s: invalid forwarding type %u", __func__, ftype); 712 invalid: 713 free(listen_addr); 714 free(connect_addr); 715 buffer_put_int(r, MUX_S_FAILURE); 716 buffer_put_int(r, rid); 717 buffer_put_cstring(r, "Invalid forwarding request"); 718 return 0; 719 } 720 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 721 logit("%s: streamlocal and dynamic forwards " 722 "are mutually exclusive", __func__); 723 goto invalid; 724 } 725 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 726 logit("%s: invalid listen port %u", __func__, 727 fwd.listen_port); 728 goto invalid; 729 } 730 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 731 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 732 logit("%s: invalid connect port %u", __func__, 733 fwd.connect_port); 734 goto invalid; 735 } 736 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 737 logit("%s: missing connect host", __func__); 738 goto invalid; 739 } 740 741 /* Skip forwards that have already been requested */ 742 switch (ftype) { 743 case MUX_FWD_LOCAL: 744 case MUX_FWD_DYNAMIC: 745 for (i = 0; i < options.num_local_forwards; i++) { 746 if (compare_forward(&fwd, 747 options.local_forwards + i)) { 748 exists: 749 debug2("%s: found existing forwarding", 750 __func__); 751 buffer_put_int(r, MUX_S_OK); 752 buffer_put_int(r, rid); 753 goto out; 754 } 755 } 756 break; 757 case MUX_FWD_REMOTE: 758 for (i = 0; i < options.num_remote_forwards; i++) { 759 if (compare_forward(&fwd, 760 options.remote_forwards + i)) { 761 if (fwd.listen_port != 0) 762 goto exists; 763 debug2("%s: found allocated port", 764 __func__); 765 buffer_put_int(r, MUX_S_REMOTE_PORT); 766 buffer_put_int(r, rid); 767 buffer_put_int(r, 768 options.remote_forwards[i].allocated_port); 769 goto out; 770 } 771 } 772 break; 773 } 774 775 if (options.control_master == SSHCTL_MASTER_ASK || 776 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 777 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 778 debug2("%s: forwarding refused by user", __func__); 779 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 780 buffer_put_int(r, rid); 781 buffer_put_cstring(r, "Permission denied"); 782 goto out; 783 } 784 } 785 786 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 787 if (!channel_setup_local_fwd_listener(&fwd, 788 &options.fwd_opts)) { 789 fail: 790 logit("slave-requested %s failed", fwd_desc); 791 buffer_put_int(r, MUX_S_FAILURE); 792 buffer_put_int(r, rid); 793 buffer_put_cstring(r, "Port forwarding failed"); 794 goto out; 795 } 796 add_local_forward(&options, &fwd); 797 freefwd = 0; 798 } else { 799 struct mux_channel_confirm_ctx *fctx; 800 801 fwd.handle = channel_request_remote_forwarding(&fwd); 802 if (fwd.handle < 0) 803 goto fail; 804 add_remote_forward(&options, &fwd); 805 fctx = xcalloc(1, sizeof(*fctx)); 806 fctx->cid = c->self; 807 fctx->rid = rid; 808 fctx->fid = options.num_remote_forwards - 1; 809 client_register_global_confirm(mux_confirm_remote_forward, 810 fctx); 811 freefwd = 0; 812 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 813 /* delayed reply in mux_confirm_remote_forward */ 814 goto out; 815 } 816 buffer_put_int(r, MUX_S_OK); 817 buffer_put_int(r, rid); 818 out: 819 free(fwd_desc); 820 if (freefwd) { 821 free(fwd.listen_host); 822 free(fwd.listen_path); 823 free(fwd.connect_host); 824 free(fwd.connect_path); 825 } 826 return ret; 827 } 828 829 static int 830 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 831 { 832 struct Forward fwd, *found_fwd; 833 char *fwd_desc = NULL; 834 const char *error_reason = NULL; 835 char *listen_addr = NULL, *connect_addr = NULL; 836 u_int ftype; 837 int i, ret = 0; 838 u_int lport, cport; 839 840 memset(&fwd, 0, sizeof(fwd)); 841 842 if (buffer_get_int_ret(&ftype, m) != 0 || 843 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 844 buffer_get_int_ret(&lport, m) != 0 || 845 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 846 buffer_get_int_ret(&cport, m) != 0 || 847 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 848 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 849 error("%s: malformed message", __func__); 850 ret = -1; 851 goto out; 852 } 853 854 if (*listen_addr == '\0') { 855 free(listen_addr); 856 listen_addr = NULL; 857 } 858 if (*connect_addr == '\0') { 859 free(connect_addr); 860 connect_addr = NULL; 861 } 862 863 memset(&fwd, 0, sizeof(fwd)); 864 fwd.listen_port = lport; 865 if (fwd.listen_port == PORT_STREAMLOCAL) 866 fwd.listen_path = listen_addr; 867 else 868 fwd.listen_host = listen_addr; 869 fwd.connect_port = cport; 870 if (fwd.connect_port == PORT_STREAMLOCAL) 871 fwd.connect_path = connect_addr; 872 else 873 fwd.connect_host = connect_addr; 874 875 debug2("%s: channel %d: request cancel %s", __func__, c->self, 876 (fwd_desc = format_forward(ftype, &fwd))); 877 878 /* make sure this has been requested */ 879 found_fwd = NULL; 880 switch (ftype) { 881 case MUX_FWD_LOCAL: 882 case MUX_FWD_DYNAMIC: 883 for (i = 0; i < options.num_local_forwards; i++) { 884 if (compare_forward(&fwd, 885 options.local_forwards + i)) { 886 found_fwd = options.local_forwards + i; 887 break; 888 } 889 } 890 break; 891 case MUX_FWD_REMOTE: 892 for (i = 0; i < options.num_remote_forwards; i++) { 893 if (compare_forward(&fwd, 894 options.remote_forwards + i)) { 895 found_fwd = options.remote_forwards + i; 896 break; 897 } 898 } 899 break; 900 } 901 902 if (found_fwd == NULL) 903 error_reason = "port not forwarded"; 904 else if (ftype == MUX_FWD_REMOTE) { 905 /* 906 * This shouldn't fail unless we confused the host/port 907 * between options.remote_forwards and permitted_opens. 908 * However, for dynamic allocated listen ports we need 909 * to use the actual listen port. 910 */ 911 if (channel_request_rforward_cancel(found_fwd) == -1) 912 error_reason = "port not in permitted opens"; 913 } else { /* local and dynamic forwards */ 914 /* Ditto */ 915 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 916 &options.fwd_opts) == -1) 917 error_reason = "port not found"; 918 } 919 920 if (error_reason == NULL) { 921 buffer_put_int(r, MUX_S_OK); 922 buffer_put_int(r, rid); 923 924 free(found_fwd->listen_host); 925 free(found_fwd->listen_path); 926 free(found_fwd->connect_host); 927 free(found_fwd->connect_path); 928 found_fwd->listen_host = found_fwd->connect_host = NULL; 929 found_fwd->listen_path = found_fwd->connect_path = NULL; 930 found_fwd->listen_port = found_fwd->connect_port = 0; 931 } else { 932 buffer_put_int(r, MUX_S_FAILURE); 933 buffer_put_int(r, rid); 934 buffer_put_cstring(r, error_reason); 935 } 936 out: 937 free(fwd_desc); 938 free(listen_addr); 939 free(connect_addr); 940 941 return ret; 942 } 943 944 static int 945 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 946 { 947 Channel *nc; 948 char *reserved, *chost; 949 u_int cport, i, j; 950 int new_fd[2]; 951 struct mux_stdio_confirm_ctx *cctx; 952 953 chost = reserved = NULL; 954 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 955 (chost = buffer_get_string_ret(m, NULL)) == NULL || 956 buffer_get_int_ret(&cport, m) != 0) { 957 free(reserved); 958 free(chost); 959 error("%s: malformed message", __func__); 960 return -1; 961 } 962 free(reserved); 963 964 debug2("%s: channel %d: request stdio fwd to %s:%u", 965 __func__, c->self, chost, cport); 966 967 /* Gather fds from client */ 968 for(i = 0; i < 2; i++) { 969 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 970 error("%s: failed to receive fd %d from slave", 971 __func__, i); 972 for (j = 0; j < i; j++) 973 close(new_fd[j]); 974 free(chost); 975 976 /* prepare reply */ 977 buffer_put_int(r, MUX_S_FAILURE); 978 buffer_put_int(r, rid); 979 buffer_put_cstring(r, 980 "did not receive file descriptors"); 981 return -1; 982 } 983 } 984 985 debug3("%s: got fds stdin %d, stdout %d", __func__, 986 new_fd[0], new_fd[1]); 987 988 /* XXX support multiple child sessions in future */ 989 if (c->remote_id != -1) { 990 debug2("%s: session already open", __func__); 991 /* prepare reply */ 992 buffer_put_int(r, MUX_S_FAILURE); 993 buffer_put_int(r, rid); 994 buffer_put_cstring(r, "Multiple sessions not supported"); 995 cleanup: 996 close(new_fd[0]); 997 close(new_fd[1]); 998 free(chost); 999 return 0; 1000 } 1001 1002 if (options.control_master == SSHCTL_MASTER_ASK || 1003 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1004 if (!ask_permission("Allow forward to %s:%u? ", 1005 chost, cport)) { 1006 debug2("%s: stdio fwd refused by user", __func__); 1007 /* prepare reply */ 1008 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1009 buffer_put_int(r, rid); 1010 buffer_put_cstring(r, "Permission denied"); 1011 goto cleanup; 1012 } 1013 } 1014 1015 /* enable nonblocking unless tty */ 1016 if (!isatty(new_fd[0])) 1017 set_nonblock(new_fd[0]); 1018 if (!isatty(new_fd[1])) 1019 set_nonblock(new_fd[1]); 1020 1021 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1022 1023 nc->ctl_chan = c->self; /* link session -> control channel */ 1024 c->remote_id = nc->self; /* link control -> session channel */ 1025 1026 debug2("%s: channel_new: %d linked to control channel %d", 1027 __func__, nc->self, nc->ctl_chan); 1028 1029 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1030 1031 cctx = xcalloc(1, sizeof(*cctx)); 1032 cctx->rid = rid; 1033 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1034 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1035 1036 /* reply is deferred, sent by mux_session_confirm */ 1037 return 0; 1038 } 1039 1040 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1041 static void 1042 mux_stdio_confirm(int id, int success, void *arg) 1043 { 1044 struct mux_stdio_confirm_ctx *cctx = arg; 1045 Channel *c, *cc; 1046 Buffer reply; 1047 1048 if (cctx == NULL) 1049 fatal("%s: cctx == NULL", __func__); 1050 if ((c = channel_by_id(id)) == NULL) 1051 fatal("%s: no channel for id %d", __func__, id); 1052 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1053 fatal("%s: channel %d lacks control channel %d", __func__, 1054 id, c->ctl_chan); 1055 1056 if (!success) { 1057 debug3("%s: sending failure reply", __func__); 1058 /* prepare reply */ 1059 buffer_init(&reply); 1060 buffer_put_int(&reply, MUX_S_FAILURE); 1061 buffer_put_int(&reply, cctx->rid); 1062 buffer_put_cstring(&reply, "Session open refused by peer"); 1063 goto done; 1064 } 1065 1066 debug3("%s: sending success reply", __func__); 1067 /* prepare reply */ 1068 buffer_init(&reply); 1069 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1070 buffer_put_int(&reply, cctx->rid); 1071 buffer_put_int(&reply, c->self); 1072 1073 done: 1074 /* Send reply */ 1075 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1076 buffer_free(&reply); 1077 1078 if (cc->mux_pause <= 0) 1079 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1080 cc->mux_pause = 0; /* start processing messages again */ 1081 c->open_confirm_ctx = NULL; 1082 free(cctx); 1083 } 1084 1085 static int 1086 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1087 { 1088 debug("%s: channel %d: stop listening", __func__, c->self); 1089 1090 if (options.control_master == SSHCTL_MASTER_ASK || 1091 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1092 if (!ask_permission("Disable further multiplexing on shared " 1093 "connection to %s? ", host)) { 1094 debug2("%s: stop listen refused by user", __func__); 1095 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1096 buffer_put_int(r, rid); 1097 buffer_put_cstring(r, "Permission denied"); 1098 return 0; 1099 } 1100 } 1101 1102 if (mux_listener_channel != NULL) { 1103 channel_free(mux_listener_channel); 1104 client_stop_mux(); 1105 free(options.control_path); 1106 options.control_path = NULL; 1107 mux_listener_channel = NULL; 1108 muxserver_sock = -1; 1109 } 1110 1111 /* prepare reply */ 1112 buffer_put_int(r, MUX_S_OK); 1113 buffer_put_int(r, rid); 1114 1115 return 0; 1116 } 1117 1118 static int 1119 process_mux_proxy(u_int rid, Channel *c, Buffer *m, Buffer *r) 1120 { 1121 debug("%s: channel %d: proxy request", __func__, c->self); 1122 1123 c->mux_rcb = channel_proxy_downstream; 1124 buffer_put_int(r, MUX_S_PROXY); 1125 buffer_put_int(r, rid); 1126 1127 return 0; 1128 } 1129 1130 /* Channel callbacks fired on read/write from mux slave fd */ 1131 static int 1132 mux_master_read_cb(Channel *c) 1133 { 1134 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1135 Buffer in, out; 1136 const u_char *ptr; 1137 u_int type, rid, have, i; 1138 int ret = -1; 1139 1140 /* Setup ctx and */ 1141 if (c->mux_ctx == NULL) { 1142 state = xcalloc(1, sizeof(*state)); 1143 c->mux_ctx = state; 1144 channel_register_cleanup(c->self, 1145 mux_master_control_cleanup_cb, 0); 1146 1147 /* Send hello */ 1148 buffer_init(&out); 1149 buffer_put_int(&out, MUX_MSG_HELLO); 1150 buffer_put_int(&out, SSHMUX_VER); 1151 /* no extensions */ 1152 buffer_put_string(&c->output, buffer_ptr(&out), 1153 buffer_len(&out)); 1154 buffer_free(&out); 1155 debug3("%s: channel %d: hello sent", __func__, c->self); 1156 return 0; 1157 } 1158 1159 buffer_init(&in); 1160 buffer_init(&out); 1161 1162 /* Channel code ensures that we receive whole packets */ 1163 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1164 malf: 1165 error("%s: malformed message", __func__); 1166 goto out; 1167 } 1168 buffer_append(&in, ptr, have); 1169 1170 if (buffer_get_int_ret(&type, &in) != 0) 1171 goto malf; 1172 debug3("%s: channel %d packet type 0x%08x len %u", 1173 __func__, c->self, type, buffer_len(&in)); 1174 1175 if (type == MUX_MSG_HELLO) 1176 rid = 0; 1177 else { 1178 if (!state->hello_rcvd) { 1179 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1180 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1181 goto out; 1182 } 1183 if (buffer_get_int_ret(&rid, &in) != 0) 1184 goto malf; 1185 } 1186 1187 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1188 if (type == mux_master_handlers[i].type) { 1189 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1190 break; 1191 } 1192 } 1193 if (mux_master_handlers[i].handler == NULL) { 1194 error("%s: unsupported mux message 0x%08x", __func__, type); 1195 buffer_put_int(&out, MUX_S_FAILURE); 1196 buffer_put_int(&out, rid); 1197 buffer_put_cstring(&out, "unsupported request"); 1198 ret = 0; 1199 } 1200 /* Enqueue reply packet */ 1201 if (buffer_len(&out) != 0) { 1202 buffer_put_string(&c->output, buffer_ptr(&out), 1203 buffer_len(&out)); 1204 } 1205 out: 1206 buffer_free(&in); 1207 buffer_free(&out); 1208 return ret; 1209 } 1210 1211 void 1212 mux_exit_message(Channel *c, int exitval) 1213 { 1214 Buffer m; 1215 Channel *mux_chan; 1216 1217 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1218 exitval); 1219 1220 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1221 fatal("%s: channel %d missing mux channel %d", 1222 __func__, c->self, c->ctl_chan); 1223 1224 /* Append exit message packet to control socket output queue */ 1225 buffer_init(&m); 1226 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1227 buffer_put_int(&m, c->self); 1228 buffer_put_int(&m, exitval); 1229 1230 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1231 buffer_free(&m); 1232 } 1233 1234 void 1235 mux_tty_alloc_failed(Channel *c) 1236 { 1237 Buffer m; 1238 Channel *mux_chan; 1239 1240 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1241 1242 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1243 fatal("%s: channel %d missing mux channel %d", 1244 __func__, c->self, c->ctl_chan); 1245 1246 /* Append exit message packet to control socket output queue */ 1247 buffer_init(&m); 1248 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1249 buffer_put_int(&m, c->self); 1250 1251 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1252 buffer_free(&m); 1253 } 1254 1255 /* Prepare a mux master to listen on a Unix domain socket. */ 1256 void 1257 muxserver_listen(void) 1258 { 1259 mode_t old_umask; 1260 char *orig_control_path = options.control_path; 1261 char rbuf[16+1]; 1262 u_int i, r; 1263 int oerrno; 1264 1265 if (options.control_path == NULL || 1266 options.control_master == SSHCTL_MASTER_NO) 1267 return; 1268 1269 debug("setting up multiplex master socket"); 1270 1271 /* 1272 * Use a temporary path before listen so we can pseudo-atomically 1273 * establish the listening socket in its final location to avoid 1274 * other processes racing in between bind() and listen() and hitting 1275 * an unready socket. 1276 */ 1277 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1278 r = arc4random_uniform(26+26+10); 1279 rbuf[i] = (r < 26) ? 'a' + r : 1280 (r < 26*2) ? 'A' + r - 26 : 1281 '0' + r - 26 - 26; 1282 } 1283 rbuf[sizeof(rbuf) - 1] = '\0'; 1284 options.control_path = NULL; 1285 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1286 debug3("%s: temporary control path %s", __func__, options.control_path); 1287 1288 old_umask = umask(0177); 1289 muxserver_sock = unix_listener(options.control_path, 64, 0); 1290 oerrno = errno; 1291 umask(old_umask); 1292 if (muxserver_sock < 0) { 1293 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1294 error("ControlSocket %s already exists, " 1295 "disabling multiplexing", options.control_path); 1296 disable_mux_master: 1297 if (muxserver_sock != -1) { 1298 close(muxserver_sock); 1299 muxserver_sock = -1; 1300 } 1301 free(orig_control_path); 1302 free(options.control_path); 1303 options.control_path = NULL; 1304 options.control_master = SSHCTL_MASTER_NO; 1305 return; 1306 } else { 1307 /* unix_listener() logs the error */ 1308 cleanup_exit(255); 1309 } 1310 } 1311 1312 /* Now atomically "move" the mux socket into position */ 1313 if (link(options.control_path, orig_control_path) != 0) { 1314 if (errno != EEXIST) { 1315 fatal("%s: link mux listener %s => %s: %s", __func__, 1316 options.control_path, orig_control_path, 1317 strerror(errno)); 1318 } 1319 error("ControlSocket %s already exists, disabling multiplexing", 1320 orig_control_path); 1321 unlink(options.control_path); 1322 goto disable_mux_master; 1323 } 1324 unlink(options.control_path); 1325 free(options.control_path); 1326 options.control_path = orig_control_path; 1327 1328 set_nonblock(muxserver_sock); 1329 1330 mux_listener_channel = channel_new("mux listener", 1331 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1332 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1333 0, options.control_path, 1); 1334 mux_listener_channel->mux_rcb = mux_master_read_cb; 1335 debug3("%s: mux listener channel %d fd %d", __func__, 1336 mux_listener_channel->self, mux_listener_channel->sock); 1337 } 1338 1339 /* Callback on open confirmation in mux master for a mux client session. */ 1340 static void 1341 mux_session_confirm(int id, int success, void *arg) 1342 { 1343 struct mux_session_confirm_ctx *cctx = arg; 1344 const char *display; 1345 Channel *c, *cc; 1346 int i; 1347 Buffer reply; 1348 1349 if (cctx == NULL) 1350 fatal("%s: cctx == NULL", __func__); 1351 if ((c = channel_by_id(id)) == NULL) 1352 fatal("%s: no channel for id %d", __func__, id); 1353 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1354 fatal("%s: channel %d lacks control channel %d", __func__, 1355 id, c->ctl_chan); 1356 1357 if (!success) { 1358 debug3("%s: sending failure reply", __func__); 1359 /* prepare reply */ 1360 buffer_init(&reply); 1361 buffer_put_int(&reply, MUX_S_FAILURE); 1362 buffer_put_int(&reply, cctx->rid); 1363 buffer_put_cstring(&reply, "Session open refused by peer"); 1364 goto done; 1365 } 1366 1367 display = getenv("DISPLAY"); 1368 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1369 char *proto, *data; 1370 1371 /* Get reasonable local authentication information. */ 1372 if (client_x11_get_proto(display, options.xauth_location, 1373 options.forward_x11_trusted, options.forward_x11_timeout, 1374 &proto, &data) == 0) { 1375 /* Request forwarding with authentication spoofing. */ 1376 debug("Requesting X11 forwarding with authentication " 1377 "spoofing."); 1378 x11_request_forwarding_with_spoofing(id, display, proto, 1379 data, 1); 1380 /* XXX exit_on_forward_failure */ 1381 client_expect_confirm(id, "X11 forwarding", 1382 CONFIRM_WARN); 1383 } 1384 } 1385 1386 if (cctx->want_agent_fwd && options.forward_agent) { 1387 debug("Requesting authentication agent forwarding."); 1388 channel_request_start(id, "auth-agent-req (at) openssh.com", 0); 1389 packet_send(); 1390 } 1391 1392 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1393 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1394 1395 debug3("%s: sending success reply", __func__); 1396 /* prepare reply */ 1397 buffer_init(&reply); 1398 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1399 buffer_put_int(&reply, cctx->rid); 1400 buffer_put_int(&reply, c->self); 1401 1402 done: 1403 /* Send reply */ 1404 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1405 buffer_free(&reply); 1406 1407 if (cc->mux_pause <= 0) 1408 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1409 cc->mux_pause = 0; /* start processing messages again */ 1410 c->open_confirm_ctx = NULL; 1411 buffer_free(&cctx->cmd); 1412 free(cctx->term); 1413 if (cctx->env != NULL) { 1414 for (i = 0; cctx->env[i] != NULL; i++) 1415 free(cctx->env[i]); 1416 free(cctx->env); 1417 } 1418 free(cctx); 1419 } 1420 1421 /* ** Multiplexing client support */ 1422 1423 /* Exit signal handler */ 1424 static void 1425 control_client_sighandler(int signo) 1426 { 1427 muxclient_terminate = signo; 1428 } 1429 1430 /* 1431 * Relay signal handler - used to pass some signals from mux client to 1432 * mux master. 1433 */ 1434 static void 1435 control_client_sigrelay(int signo) 1436 { 1437 int save_errno = errno; 1438 1439 if (muxserver_pid > 1) 1440 kill(muxserver_pid, signo); 1441 1442 errno = save_errno; 1443 } 1444 1445 static int 1446 mux_client_read(int fd, Buffer *b, u_int need) 1447 { 1448 u_int have; 1449 ssize_t len; 1450 u_char *p; 1451 struct pollfd pfd; 1452 1453 pfd.fd = fd; 1454 pfd.events = POLLIN; 1455 p = buffer_append_space(b, need); 1456 for (have = 0; have < need; ) { 1457 if (muxclient_terminate) { 1458 errno = EINTR; 1459 return -1; 1460 } 1461 len = read(fd, p + have, need - have); 1462 if (len < 0) { 1463 switch (errno) { 1464 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1465 case EWOULDBLOCK: 1466 #endif 1467 case EAGAIN: 1468 (void)poll(&pfd, 1, -1); 1469 /* FALLTHROUGH */ 1470 case EINTR: 1471 continue; 1472 default: 1473 return -1; 1474 } 1475 } 1476 if (len == 0) { 1477 errno = EPIPE; 1478 return -1; 1479 } 1480 have += (u_int)len; 1481 } 1482 return 0; 1483 } 1484 1485 static int 1486 mux_client_write_packet(int fd, Buffer *m) 1487 { 1488 Buffer queue; 1489 u_int have, need; 1490 int oerrno, len; 1491 u_char *ptr; 1492 struct pollfd pfd; 1493 1494 pfd.fd = fd; 1495 pfd.events = POLLOUT; 1496 buffer_init(&queue); 1497 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1498 1499 need = buffer_len(&queue); 1500 ptr = buffer_ptr(&queue); 1501 1502 for (have = 0; have < need; ) { 1503 if (muxclient_terminate) { 1504 buffer_free(&queue); 1505 errno = EINTR; 1506 return -1; 1507 } 1508 len = write(fd, ptr + have, need - have); 1509 if (len < 0) { 1510 switch (errno) { 1511 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1512 case EWOULDBLOCK: 1513 #endif 1514 case EAGAIN: 1515 (void)poll(&pfd, 1, -1); 1516 /* FALLTHROUGH */ 1517 case EINTR: 1518 continue; 1519 default: 1520 oerrno = errno; 1521 buffer_free(&queue); 1522 errno = oerrno; 1523 return -1; 1524 } 1525 } 1526 if (len == 0) { 1527 buffer_free(&queue); 1528 errno = EPIPE; 1529 return -1; 1530 } 1531 have += (u_int)len; 1532 } 1533 buffer_free(&queue); 1534 return 0; 1535 } 1536 1537 static int 1538 mux_client_read_packet(int fd, Buffer *m) 1539 { 1540 Buffer queue; 1541 u_int need, have; 1542 const u_char *ptr; 1543 int oerrno; 1544 1545 buffer_init(&queue); 1546 if (mux_client_read(fd, &queue, 4) != 0) { 1547 if ((oerrno = errno) == EPIPE) 1548 debug3("%s: read header failed: %s", __func__, 1549 strerror(errno)); 1550 buffer_free(&queue); 1551 errno = oerrno; 1552 return -1; 1553 } 1554 need = get_u32(buffer_ptr(&queue)); 1555 if (mux_client_read(fd, &queue, need) != 0) { 1556 oerrno = errno; 1557 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1558 buffer_free(&queue); 1559 errno = oerrno; 1560 return -1; 1561 } 1562 ptr = buffer_get_string_ptr(&queue, &have); 1563 buffer_append(m, ptr, have); 1564 buffer_free(&queue); 1565 return 0; 1566 } 1567 1568 static int 1569 mux_client_hello_exchange(int fd) 1570 { 1571 Buffer m; 1572 u_int type, ver; 1573 1574 buffer_init(&m); 1575 buffer_put_int(&m, MUX_MSG_HELLO); 1576 buffer_put_int(&m, SSHMUX_VER); 1577 /* no extensions */ 1578 1579 if (mux_client_write_packet(fd, &m) != 0) 1580 fatal("%s: write packet: %s", __func__, strerror(errno)); 1581 1582 buffer_clear(&m); 1583 1584 /* Read their HELLO */ 1585 if (mux_client_read_packet(fd, &m) != 0) { 1586 buffer_free(&m); 1587 return -1; 1588 } 1589 1590 type = buffer_get_int(&m); 1591 if (type != MUX_MSG_HELLO) 1592 fatal("%s: expected HELLO (%u) received %u", 1593 __func__, MUX_MSG_HELLO, type); 1594 ver = buffer_get_int(&m); 1595 if (ver != SSHMUX_VER) 1596 fatal("Unsupported multiplexing protocol version %d " 1597 "(expected %d)", ver, SSHMUX_VER); 1598 debug2("%s: master version %u", __func__, ver); 1599 /* No extensions are presently defined */ 1600 while (buffer_len(&m) > 0) { 1601 char *name = buffer_get_string(&m, NULL); 1602 char *value = buffer_get_string(&m, NULL); 1603 1604 debug2("Unrecognised master extension \"%s\"", name); 1605 free(name); 1606 free(value); 1607 } 1608 buffer_free(&m); 1609 return 0; 1610 } 1611 1612 static u_int 1613 mux_client_request_alive(int fd) 1614 { 1615 Buffer m; 1616 char *e; 1617 u_int pid, type, rid; 1618 1619 debug3("%s: entering", __func__); 1620 1621 buffer_init(&m); 1622 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1623 buffer_put_int(&m, muxclient_request_id); 1624 1625 if (mux_client_write_packet(fd, &m) != 0) 1626 fatal("%s: write packet: %s", __func__, strerror(errno)); 1627 1628 buffer_clear(&m); 1629 1630 /* Read their reply */ 1631 if (mux_client_read_packet(fd, &m) != 0) { 1632 buffer_free(&m); 1633 return 0; 1634 } 1635 1636 type = buffer_get_int(&m); 1637 if (type != MUX_S_ALIVE) { 1638 e = buffer_get_string(&m, NULL); 1639 fatal("%s: master returned error: %s", __func__, e); 1640 } 1641 1642 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1643 fatal("%s: out of sequence reply: my id %u theirs %u", 1644 __func__, muxclient_request_id, rid); 1645 pid = buffer_get_int(&m); 1646 buffer_free(&m); 1647 1648 debug3("%s: done pid = %u", __func__, pid); 1649 1650 muxclient_request_id++; 1651 1652 return pid; 1653 } 1654 1655 static void 1656 mux_client_request_terminate(int fd) 1657 { 1658 Buffer m; 1659 char *e; 1660 u_int type, rid; 1661 1662 debug3("%s: entering", __func__); 1663 1664 buffer_init(&m); 1665 buffer_put_int(&m, MUX_C_TERMINATE); 1666 buffer_put_int(&m, muxclient_request_id); 1667 1668 if (mux_client_write_packet(fd, &m) != 0) 1669 fatal("%s: write packet: %s", __func__, strerror(errno)); 1670 1671 buffer_clear(&m); 1672 1673 /* Read their reply */ 1674 if (mux_client_read_packet(fd, &m) != 0) { 1675 /* Remote end exited already */ 1676 if (errno == EPIPE) { 1677 buffer_free(&m); 1678 return; 1679 } 1680 fatal("%s: read from master failed: %s", 1681 __func__, strerror(errno)); 1682 } 1683 1684 type = buffer_get_int(&m); 1685 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1686 fatal("%s: out of sequence reply: my id %u theirs %u", 1687 __func__, muxclient_request_id, rid); 1688 switch (type) { 1689 case MUX_S_OK: 1690 break; 1691 case MUX_S_PERMISSION_DENIED: 1692 e = buffer_get_string(&m, NULL); 1693 fatal("Master refused termination request: %s", e); 1694 case MUX_S_FAILURE: 1695 e = buffer_get_string(&m, NULL); 1696 fatal("%s: termination request failed: %s", __func__, e); 1697 default: 1698 fatal("%s: unexpected response from master 0x%08x", 1699 __func__, type); 1700 } 1701 buffer_free(&m); 1702 muxclient_request_id++; 1703 } 1704 1705 static int 1706 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1707 { 1708 Buffer m; 1709 char *e, *fwd_desc; 1710 u_int type, rid; 1711 1712 fwd_desc = format_forward(ftype, fwd); 1713 debug("Requesting %s %s", 1714 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1715 free(fwd_desc); 1716 1717 buffer_init(&m); 1718 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1719 buffer_put_int(&m, muxclient_request_id); 1720 buffer_put_int(&m, ftype); 1721 if (fwd->listen_path != NULL) { 1722 buffer_put_cstring(&m, fwd->listen_path); 1723 } else { 1724 buffer_put_cstring(&m, 1725 fwd->listen_host == NULL ? "" : 1726 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1727 } 1728 buffer_put_int(&m, fwd->listen_port); 1729 if (fwd->connect_path != NULL) { 1730 buffer_put_cstring(&m, fwd->connect_path); 1731 } else { 1732 buffer_put_cstring(&m, 1733 fwd->connect_host == NULL ? "" : fwd->connect_host); 1734 } 1735 buffer_put_int(&m, fwd->connect_port); 1736 1737 if (mux_client_write_packet(fd, &m) != 0) 1738 fatal("%s: write packet: %s", __func__, strerror(errno)); 1739 1740 buffer_clear(&m); 1741 1742 /* Read their reply */ 1743 if (mux_client_read_packet(fd, &m) != 0) { 1744 buffer_free(&m); 1745 return -1; 1746 } 1747 1748 type = buffer_get_int(&m); 1749 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1750 fatal("%s: out of sequence reply: my id %u theirs %u", 1751 __func__, muxclient_request_id, rid); 1752 switch (type) { 1753 case MUX_S_OK: 1754 break; 1755 case MUX_S_REMOTE_PORT: 1756 if (cancel_flag) 1757 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1758 fwd->allocated_port = buffer_get_int(&m); 1759 verbose("Allocated port %u for remote forward to %s:%d", 1760 fwd->allocated_port, 1761 fwd->connect_host ? fwd->connect_host : "", 1762 fwd->connect_port); 1763 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1764 fprintf(stdout, "%i\n", fwd->allocated_port); 1765 break; 1766 case MUX_S_PERMISSION_DENIED: 1767 e = buffer_get_string(&m, NULL); 1768 buffer_free(&m); 1769 error("Master refused forwarding request: %s", e); 1770 return -1; 1771 case MUX_S_FAILURE: 1772 e = buffer_get_string(&m, NULL); 1773 buffer_free(&m); 1774 error("%s: forwarding request failed: %s", __func__, e); 1775 return -1; 1776 default: 1777 fatal("%s: unexpected response from master 0x%08x", 1778 __func__, type); 1779 } 1780 buffer_free(&m); 1781 1782 muxclient_request_id++; 1783 return 0; 1784 } 1785 1786 static int 1787 mux_client_forwards(int fd, int cancel_flag) 1788 { 1789 int i, ret = 0; 1790 1791 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1792 cancel_flag ? "cancel" : "request", 1793 options.num_local_forwards, options.num_remote_forwards); 1794 1795 /* XXX ExitOnForwardingFailure */ 1796 for (i = 0; i < options.num_local_forwards; i++) { 1797 if (mux_client_forward(fd, cancel_flag, 1798 options.local_forwards[i].connect_port == 0 ? 1799 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1800 options.local_forwards + i) != 0) 1801 ret = -1; 1802 } 1803 for (i = 0; i < options.num_remote_forwards; i++) { 1804 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1805 options.remote_forwards + i) != 0) 1806 ret = -1; 1807 } 1808 return ret; 1809 } 1810 1811 static int 1812 mux_client_request_session(int fd) 1813 { 1814 Buffer m; 1815 char *e, *term; 1816 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1817 extern char **environ; 1818 int devnull, rawmode; 1819 1820 debug3("%s: entering", __func__); 1821 1822 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1823 error("%s: master alive request failed", __func__); 1824 return -1; 1825 } 1826 1827 signal(SIGPIPE, SIG_IGN); 1828 1829 if (stdin_null_flag) { 1830 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1831 fatal("open(/dev/null): %s", strerror(errno)); 1832 if (dup2(devnull, STDIN_FILENO) == -1) 1833 fatal("dup2: %s", strerror(errno)); 1834 if (devnull > STDERR_FILENO) 1835 close(devnull); 1836 } 1837 1838 term = getenv("TERM"); 1839 1840 buffer_init(&m); 1841 buffer_put_int(&m, MUX_C_NEW_SESSION); 1842 buffer_put_int(&m, muxclient_request_id); 1843 buffer_put_cstring(&m, ""); /* reserved */ 1844 buffer_put_int(&m, tty_flag); 1845 buffer_put_int(&m, options.forward_x11); 1846 buffer_put_int(&m, options.forward_agent); 1847 buffer_put_int(&m, subsystem_flag); 1848 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1849 0xffffffff : (u_int)options.escape_char); 1850 buffer_put_cstring(&m, term == NULL ? "" : term); 1851 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1852 1853 if (options.num_send_env > 0 && environ != NULL) { 1854 /* Pass environment */ 1855 for (i = 0; environ[i] != NULL; i++) { 1856 if (env_permitted(environ[i])) { 1857 buffer_put_cstring(&m, environ[i]); 1858 } 1859 } 1860 } 1861 1862 if (mux_client_write_packet(fd, &m) != 0) 1863 fatal("%s: write packet: %s", __func__, strerror(errno)); 1864 1865 /* Send the stdio file descriptors */ 1866 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1867 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1868 mm_send_fd(fd, STDERR_FILENO) == -1) 1869 fatal("%s: send fds failed", __func__); 1870 1871 debug3("%s: session request sent", __func__); 1872 1873 /* Read their reply */ 1874 buffer_clear(&m); 1875 if (mux_client_read_packet(fd, &m) != 0) { 1876 error("%s: read from master failed: %s", 1877 __func__, strerror(errno)); 1878 buffer_free(&m); 1879 return -1; 1880 } 1881 1882 type = buffer_get_int(&m); 1883 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1884 fatal("%s: out of sequence reply: my id %u theirs %u", 1885 __func__, muxclient_request_id, rid); 1886 switch (type) { 1887 case MUX_S_SESSION_OPENED: 1888 sid = buffer_get_int(&m); 1889 debug("%s: master session id: %u", __func__, sid); 1890 break; 1891 case MUX_S_PERMISSION_DENIED: 1892 e = buffer_get_string(&m, NULL); 1893 buffer_free(&m); 1894 error("Master refused session request: %s", e); 1895 return -1; 1896 case MUX_S_FAILURE: 1897 e = buffer_get_string(&m, NULL); 1898 buffer_free(&m); 1899 error("%s: session request failed: %s", __func__, e); 1900 return -1; 1901 default: 1902 buffer_free(&m); 1903 error("%s: unexpected response from master 0x%08x", 1904 __func__, type); 1905 return -1; 1906 } 1907 muxclient_request_id++; 1908 1909 if (pledge("stdio proc tty", NULL) == -1) 1910 fatal("%s pledge(): %s", __func__, strerror(errno)); 1911 platform_pledge_mux(); 1912 1913 signal(SIGHUP, control_client_sighandler); 1914 signal(SIGINT, control_client_sighandler); 1915 signal(SIGTERM, control_client_sighandler); 1916 signal(SIGWINCH, control_client_sigrelay); 1917 1918 rawmode = tty_flag; 1919 if (tty_flag) 1920 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1921 1922 /* 1923 * Stick around until the controlee closes the client_fd. 1924 * Before it does, it is expected to write an exit message. 1925 * This process must read the value and wait for the closure of 1926 * the client_fd; if this one closes early, the multiplex master will 1927 * terminate early too (possibly losing data). 1928 */ 1929 for (exitval = 255, exitval_seen = 0;;) { 1930 buffer_clear(&m); 1931 if (mux_client_read_packet(fd, &m) != 0) 1932 break; 1933 type = buffer_get_int(&m); 1934 switch (type) { 1935 case MUX_S_TTY_ALLOC_FAIL: 1936 if ((esid = buffer_get_int(&m)) != sid) 1937 fatal("%s: tty alloc fail on unknown session: " 1938 "my id %u theirs %u", 1939 __func__, sid, esid); 1940 leave_raw_mode(options.request_tty == 1941 REQUEST_TTY_FORCE); 1942 rawmode = 0; 1943 continue; 1944 case MUX_S_EXIT_MESSAGE: 1945 if ((esid = buffer_get_int(&m)) != sid) 1946 fatal("%s: exit on unknown session: " 1947 "my id %u theirs %u", 1948 __func__, sid, esid); 1949 if (exitval_seen) 1950 fatal("%s: exitval sent twice", __func__); 1951 exitval = buffer_get_int(&m); 1952 exitval_seen = 1; 1953 continue; 1954 default: 1955 e = buffer_get_string(&m, NULL); 1956 fatal("%s: master returned error: %s", __func__, e); 1957 } 1958 } 1959 1960 close(fd); 1961 if (rawmode) 1962 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1963 1964 if (muxclient_terminate) { 1965 debug2("Exiting on signal %d", muxclient_terminate); 1966 exitval = 255; 1967 } else if (!exitval_seen) { 1968 debug2("Control master terminated unexpectedly"); 1969 exitval = 255; 1970 } else 1971 debug2("Received exit status from master %d", exitval); 1972 1973 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1974 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1975 1976 exit(exitval); 1977 } 1978 1979 static int 1980 mux_client_proxy(int fd) 1981 { 1982 Buffer m; 1983 char *e; 1984 u_int type, rid; 1985 1986 buffer_init(&m); 1987 buffer_put_int(&m, MUX_C_PROXY); 1988 buffer_put_int(&m, muxclient_request_id); 1989 if (mux_client_write_packet(fd, &m) != 0) 1990 fatal("%s: write packet: %s", __func__, strerror(errno)); 1991 1992 buffer_clear(&m); 1993 1994 /* Read their reply */ 1995 if (mux_client_read_packet(fd, &m) != 0) { 1996 buffer_free(&m); 1997 return 0; 1998 } 1999 type = buffer_get_int(&m); 2000 if (type != MUX_S_PROXY) { 2001 e = buffer_get_string(&m, NULL); 2002 fatal("%s: master returned error: %s", __func__, e); 2003 } 2004 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2005 fatal("%s: out of sequence reply: my id %u theirs %u", 2006 __func__, muxclient_request_id, rid); 2007 buffer_free(&m); 2008 2009 debug3("%s: done", __func__); 2010 muxclient_request_id++; 2011 return 0; 2012 } 2013 2014 static int 2015 mux_client_request_stdio_fwd(int fd) 2016 { 2017 Buffer m; 2018 char *e; 2019 u_int type, rid, sid; 2020 int devnull; 2021 2022 debug3("%s: entering", __func__); 2023 2024 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2025 error("%s: master alive request failed", __func__); 2026 return -1; 2027 } 2028 2029 signal(SIGPIPE, SIG_IGN); 2030 2031 if (stdin_null_flag) { 2032 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 2033 fatal("open(/dev/null): %s", strerror(errno)); 2034 if (dup2(devnull, STDIN_FILENO) == -1) 2035 fatal("dup2: %s", strerror(errno)); 2036 if (devnull > STDERR_FILENO) 2037 close(devnull); 2038 } 2039 2040 buffer_init(&m); 2041 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 2042 buffer_put_int(&m, muxclient_request_id); 2043 buffer_put_cstring(&m, ""); /* reserved */ 2044 buffer_put_cstring(&m, options.stdio_forward_host); 2045 buffer_put_int(&m, options.stdio_forward_port); 2046 2047 if (mux_client_write_packet(fd, &m) != 0) 2048 fatal("%s: write packet: %s", __func__, strerror(errno)); 2049 2050 /* Send the stdio file descriptors */ 2051 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2052 mm_send_fd(fd, STDOUT_FILENO) == -1) 2053 fatal("%s: send fds failed", __func__); 2054 2055 if (pledge("stdio proc tty", NULL) == -1) 2056 fatal("%s pledge(): %s", __func__, strerror(errno)); 2057 platform_pledge_mux(); 2058 2059 debug3("%s: stdio forward request sent", __func__); 2060 2061 /* Read their reply */ 2062 buffer_clear(&m); 2063 2064 if (mux_client_read_packet(fd, &m) != 0) { 2065 error("%s: read from master failed: %s", 2066 __func__, strerror(errno)); 2067 buffer_free(&m); 2068 return -1; 2069 } 2070 2071 type = buffer_get_int(&m); 2072 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2073 fatal("%s: out of sequence reply: my id %u theirs %u", 2074 __func__, muxclient_request_id, rid); 2075 switch (type) { 2076 case MUX_S_SESSION_OPENED: 2077 sid = buffer_get_int(&m); 2078 debug("%s: master session id: %u", __func__, sid); 2079 break; 2080 case MUX_S_PERMISSION_DENIED: 2081 e = buffer_get_string(&m, NULL); 2082 buffer_free(&m); 2083 fatal("Master refused stdio forwarding request: %s", e); 2084 case MUX_S_FAILURE: 2085 e = buffer_get_string(&m, NULL); 2086 buffer_free(&m); 2087 fatal("Stdio forwarding request failed: %s", e); 2088 default: 2089 buffer_free(&m); 2090 error("%s: unexpected response from master 0x%08x", 2091 __func__, type); 2092 return -1; 2093 } 2094 muxclient_request_id++; 2095 2096 signal(SIGHUP, control_client_sighandler); 2097 signal(SIGINT, control_client_sighandler); 2098 signal(SIGTERM, control_client_sighandler); 2099 signal(SIGWINCH, control_client_sigrelay); 2100 2101 /* 2102 * Stick around until the controlee closes the client_fd. 2103 */ 2104 buffer_clear(&m); 2105 if (mux_client_read_packet(fd, &m) != 0) { 2106 if (errno == EPIPE || 2107 (errno == EINTR && muxclient_terminate != 0)) 2108 return 0; 2109 fatal("%s: mux_client_read_packet: %s", 2110 __func__, strerror(errno)); 2111 } 2112 fatal("%s: master returned unexpected message %u", __func__, type); 2113 } 2114 2115 static void 2116 mux_client_request_stop_listening(int fd) 2117 { 2118 Buffer m; 2119 char *e; 2120 u_int type, rid; 2121 2122 debug3("%s: entering", __func__); 2123 2124 buffer_init(&m); 2125 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2126 buffer_put_int(&m, muxclient_request_id); 2127 2128 if (mux_client_write_packet(fd, &m) != 0) 2129 fatal("%s: write packet: %s", __func__, strerror(errno)); 2130 2131 buffer_clear(&m); 2132 2133 /* Read their reply */ 2134 if (mux_client_read_packet(fd, &m) != 0) 2135 fatal("%s: read from master failed: %s", 2136 __func__, strerror(errno)); 2137 2138 type = buffer_get_int(&m); 2139 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2140 fatal("%s: out of sequence reply: my id %u theirs %u", 2141 __func__, muxclient_request_id, rid); 2142 switch (type) { 2143 case MUX_S_OK: 2144 break; 2145 case MUX_S_PERMISSION_DENIED: 2146 e = buffer_get_string(&m, NULL); 2147 fatal("Master refused stop listening request: %s", e); 2148 case MUX_S_FAILURE: 2149 e = buffer_get_string(&m, NULL); 2150 fatal("%s: stop listening request failed: %s", __func__, e); 2151 default: 2152 fatal("%s: unexpected response from master 0x%08x", 2153 __func__, type); 2154 } 2155 buffer_free(&m); 2156 muxclient_request_id++; 2157 } 2158 2159 /* Multiplex client main loop. */ 2160 int 2161 muxclient(const char *path) 2162 { 2163 struct sockaddr_un addr; 2164 int sock; 2165 u_int pid; 2166 2167 if (muxclient_command == 0) { 2168 if (options.stdio_forward_host != NULL) 2169 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2170 else 2171 muxclient_command = SSHMUX_COMMAND_OPEN; 2172 } 2173 2174 switch (options.control_master) { 2175 case SSHCTL_MASTER_AUTO: 2176 case SSHCTL_MASTER_AUTO_ASK: 2177 debug("auto-mux: Trying existing master"); 2178 /* FALLTHROUGH */ 2179 case SSHCTL_MASTER_NO: 2180 break; 2181 default: 2182 return -1; 2183 } 2184 2185 memset(&addr, '\0', sizeof(addr)); 2186 addr.sun_family = AF_UNIX; 2187 2188 if (strlcpy(addr.sun_path, path, 2189 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2190 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2191 (unsigned int)sizeof(addr.sun_path)); 2192 2193 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2194 fatal("%s socket(): %s", __func__, strerror(errno)); 2195 2196 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2197 switch (muxclient_command) { 2198 case SSHMUX_COMMAND_OPEN: 2199 case SSHMUX_COMMAND_STDIO_FWD: 2200 break; 2201 default: 2202 fatal("Control socket connect(%.100s): %s", path, 2203 strerror(errno)); 2204 } 2205 if (errno == ECONNREFUSED && 2206 options.control_master != SSHCTL_MASTER_NO) { 2207 debug("Stale control socket %.100s, unlinking", path); 2208 unlink(path); 2209 } else if (errno == ENOENT) { 2210 debug("Control socket \"%.100s\" does not exist", path); 2211 } else { 2212 error("Control socket connect(%.100s): %s", path, 2213 strerror(errno)); 2214 } 2215 close(sock); 2216 return -1; 2217 } 2218 set_nonblock(sock); 2219 2220 if (mux_client_hello_exchange(sock) != 0) { 2221 error("%s: master hello exchange failed", __func__); 2222 close(sock); 2223 return -1; 2224 } 2225 2226 switch (muxclient_command) { 2227 case SSHMUX_COMMAND_ALIVE_CHECK: 2228 if ((pid = mux_client_request_alive(sock)) == 0) 2229 fatal("%s: master alive check failed", __func__); 2230 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2231 exit(0); 2232 case SSHMUX_COMMAND_TERMINATE: 2233 mux_client_request_terminate(sock); 2234 if (options.log_level != SYSLOG_LEVEL_QUIET) 2235 fprintf(stderr, "Exit request sent.\r\n"); 2236 exit(0); 2237 case SSHMUX_COMMAND_FORWARD: 2238 if (mux_client_forwards(sock, 0) != 0) 2239 fatal("%s: master forward request failed", __func__); 2240 exit(0); 2241 case SSHMUX_COMMAND_OPEN: 2242 if (mux_client_forwards(sock, 0) != 0) { 2243 error("%s: master forward request failed", __func__); 2244 return -1; 2245 } 2246 mux_client_request_session(sock); 2247 return -1; 2248 case SSHMUX_COMMAND_STDIO_FWD: 2249 mux_client_request_stdio_fwd(sock); 2250 exit(0); 2251 case SSHMUX_COMMAND_STOP: 2252 mux_client_request_stop_listening(sock); 2253 if (options.log_level != SYSLOG_LEVEL_QUIET) 2254 fprintf(stderr, "Stop listening request sent.\r\n"); 2255 exit(0); 2256 case SSHMUX_COMMAND_CANCEL_FWD: 2257 if (mux_client_forwards(sock, 1) != 0) 2258 error("%s: master cancel forward request failed", 2259 __func__); 2260 exit(0); 2261 case SSHMUX_COMMAND_PROXY: 2262 mux_client_proxy(sock); 2263 return (sock); 2264 default: 2265 fatal("unrecognised muxclient_command %d", muxclient_command); 2266 } 2267 } 2268
