1 /* $OpenBSD: mux.c,v 1.48 2014/07/17 07:22:19 djm Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 /* 21 * TODO: 22 * - Better signalling from master to slave, especially passing of 23 * error messages 24 * - Better fall-back from mux slave error to new connection. 25 * - ExitOnForwardingFailure 26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 27 * - Support ~^Z in mux slaves. 28 * - Inspect or control sessions in master. 29 * - If we ever support the "signal" channel request, send signals on 30 * sessions in master. 31 */ 32 33 #include "includes.h" 34 35 #include <sys/types.h> 36 #include <sys/param.h> 37 #include <sys/stat.h> 38 #include <sys/socket.h> 39 #include <sys/un.h> 40 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <signal.h> 44 #include <stdarg.h> 45 #include <stddef.h> 46 #include <stdlib.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <unistd.h> 50 #ifdef HAVE_PATHS_H 51 #include <paths.h> 52 #endif 53 54 #ifdef HAVE_POLL_H 55 #include <poll.h> 56 #else 57 # ifdef HAVE_SYS_POLL_H 58 # include <sys/poll.h> 59 # endif 60 #endif 61 62 #ifdef HAVE_UTIL_H 63 # include <util.h> 64 #endif 65 66 #include "openbsd-compat/sys-queue.h" 67 #include "xmalloc.h" 68 #include "log.h" 69 #include "ssh.h" 70 #include "ssh2.h" 71 #include "pathnames.h" 72 #include "misc.h" 73 #include "match.h" 74 #include "buffer.h" 75 #include "channels.h" 76 #include "msg.h" 77 #include "packet.h" 78 #include "monitor_fdpass.h" 79 #include "sshpty.h" 80 #include "key.h" 81 #include "readconf.h" 82 #include "clientloop.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 extern char *stdio_forward_host; 93 extern int stdio_forward_port; 94 95 /* Context for session open confirmation callback */ 96 struct mux_session_confirm_ctx { 97 u_int want_tty; 98 u_int want_subsys; 99 u_int want_x_fwd; 100 u_int want_agent_fwd; 101 Buffer cmd; 102 char *term; 103 struct termios tio; 104 char **env; 105 u_int rid; 106 }; 107 108 /* Context for stdio fwd open confirmation callback */ 109 struct mux_stdio_confirm_ctx { 110 u_int rid; 111 }; 112 113 /* Context for global channel callback */ 114 struct mux_channel_confirm_ctx { 115 u_int cid; /* channel id */ 116 u_int rid; /* request id */ 117 int fid; /* forward id */ 118 }; 119 120 /* fd to control socket */ 121 int muxserver_sock = -1; 122 123 /* client request id */ 124 u_int muxclient_request_id = 0; 125 126 /* Multiplexing control command */ 127 u_int muxclient_command = 0; 128 129 /* Set when signalled. */ 130 static volatile sig_atomic_t muxclient_terminate = 0; 131 132 /* PID of multiplex server */ 133 static u_int muxserver_pid = 0; 134 135 static Channel *mux_listener_channel = NULL; 136 137 struct mux_master_state { 138 int hello_rcvd; 139 }; 140 141 /* mux protocol messages */ 142 #define MUX_MSG_HELLO 0x00000001 143 #define MUX_C_NEW_SESSION 0x10000002 144 #define MUX_C_ALIVE_CHECK 0x10000004 145 #define MUX_C_TERMINATE 0x10000005 146 #define MUX_C_OPEN_FWD 0x10000006 147 #define MUX_C_CLOSE_FWD 0x10000007 148 #define MUX_C_NEW_STDIO_FWD 0x10000008 149 #define MUX_C_STOP_LISTENING 0x10000009 150 #define MUX_S_OK 0x80000001 151 #define MUX_S_PERMISSION_DENIED 0x80000002 152 #define MUX_S_FAILURE 0x80000003 153 #define MUX_S_EXIT_MESSAGE 0x80000004 154 #define MUX_S_ALIVE 0x80000005 155 #define MUX_S_SESSION_OPENED 0x80000006 156 #define MUX_S_REMOTE_PORT 0x80000007 157 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 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 *); 175 176 static const struct { 177 u_int type; 178 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 179 } mux_master_handlers[] = { 180 { MUX_MSG_HELLO, process_mux_master_hello }, 181 { MUX_C_NEW_SESSION, process_mux_new_session }, 182 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 183 { MUX_C_TERMINATE, process_mux_terminate }, 184 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 185 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 186 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 187 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 188 { 0, NULL } 189 }; 190 191 /* Cleanup callback fired on closure of mux slave _session_ channel */ 192 /* ARGSUSED */ 193 static void 194 mux_master_session_cleanup_cb(int cid, void *unused) 195 { 196 Channel *cc, *c = channel_by_id(cid); 197 198 debug3("%s: entering for channel %d", __func__, cid); 199 if (c == NULL) 200 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 201 if (c->ctl_chan != -1) { 202 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 203 fatal("%s: channel %d missing control channel %d", 204 __func__, c->self, c->ctl_chan); 205 c->ctl_chan = -1; 206 cc->remote_id = -1; 207 chan_rcvd_oclose(cc); 208 } 209 channel_cancel_cleanup(c->self); 210 } 211 212 /* Cleanup callback fired on closure of mux slave _control_ channel */ 213 /* ARGSUSED */ 214 static void 215 mux_master_control_cleanup_cb(int cid, void *unused) 216 { 217 Channel *sc, *c = channel_by_id(cid); 218 219 debug3("%s: entering for channel %d", __func__, cid); 220 if (c == NULL) 221 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 222 if (c->remote_id != -1) { 223 if ((sc = channel_by_id(c->remote_id)) == NULL) 224 fatal("%s: channel %d missing session channel %d", 225 __func__, c->self, c->remote_id); 226 c->remote_id = -1; 227 sc->ctl_chan = -1; 228 if (sc->type != SSH_CHANNEL_OPEN && 229 sc->type != SSH_CHANNEL_OPENING) { 230 debug2("%s: channel %d: not open", __func__, sc->self); 231 chan_mark_dead(sc); 232 } else { 233 if (sc->istate == CHAN_INPUT_OPEN) 234 chan_read_failed(sc); 235 if (sc->ostate == CHAN_OUTPUT_OPEN) 236 chan_write_failed(sc); 237 } 238 } 239 channel_cancel_cleanup(c->self); 240 } 241 242 /* Check mux client environment variables before passing them to mux master. */ 243 static int 244 env_permitted(char *env) 245 { 246 int i, ret; 247 char name[1024], *cp; 248 249 if ((cp = strchr(env, '=')) == NULL || cp == env) 250 return 0; 251 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 252 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 253 error("env_permitted: name '%.100s...' too long", env); 254 return 0; 255 } 256 257 for (i = 0; i < options.num_send_env; i++) 258 if (match_pattern(name, options.send_env[i])) 259 return 1; 260 261 return 0; 262 } 263 264 /* Mux master protocol message handlers */ 265 266 static int 267 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 268 { 269 u_int ver; 270 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 271 272 if (state == NULL) 273 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 274 if (state->hello_rcvd) { 275 error("%s: HELLO received twice", __func__); 276 return -1; 277 } 278 if (buffer_get_int_ret(&ver, m) != 0) { 279 malf: 280 error("%s: malformed message", __func__); 281 return -1; 282 } 283 if (ver != SSHMUX_VER) { 284 error("Unsupported multiplexing protocol version %d " 285 "(expected %d)", ver, SSHMUX_VER); 286 return -1; 287 } 288 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 289 290 /* No extensions are presently defined */ 291 while (buffer_len(m) > 0) { 292 char *name = buffer_get_string_ret(m, NULL); 293 char *value = buffer_get_string_ret(m, NULL); 294 295 if (name == NULL || value == NULL) { 296 free(name); 297 free(value); 298 goto malf; 299 } 300 debug2("Unrecognised slave extension \"%s\"", name); 301 free(name); 302 free(value); 303 } 304 state->hello_rcvd = 1; 305 return 0; 306 } 307 308 static int 309 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 310 { 311 Channel *nc; 312 struct mux_session_confirm_ctx *cctx; 313 char *reserved, *cmd, *cp; 314 u_int i, j, len, env_len, escape_char, window, packetmax; 315 int new_fd[3]; 316 317 /* Reply for SSHMUX_COMMAND_OPEN */ 318 cctx = xcalloc(1, sizeof(*cctx)); 319 cctx->term = NULL; 320 cctx->rid = rid; 321 cmd = reserved = NULL; 322 cctx->env = NULL; 323 env_len = 0; 324 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 325 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 326 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 327 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 328 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 329 buffer_get_int_ret(&escape_char, m) != 0 || 330 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 331 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 332 malf: 333 free(cmd); 334 free(reserved); 335 for (j = 0; j < env_len; j++) 336 free(cctx->env[j]); 337 free(cctx->env); 338 free(cctx->term); 339 free(cctx); 340 error("%s: malformed message", __func__); 341 return -1; 342 } 343 free(reserved); 344 reserved = NULL; 345 346 while (buffer_len(m) > 0) { 347 #define MUX_MAX_ENV_VARS 4096 348 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 349 goto malf; 350 if (!env_permitted(cp)) { 351 free(cp); 352 continue; 353 } 354 cctx->env = xrealloc(cctx->env, env_len + 2, 355 sizeof(*cctx->env)); 356 cctx->env[env_len++] = cp; 357 cctx->env[env_len] = NULL; 358 if (env_len > MUX_MAX_ENV_VARS) { 359 error(">%d environment variables received, ignoring " 360 "additional", MUX_MAX_ENV_VARS); 361 break; 362 } 363 } 364 365 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 366 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 367 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 368 cctx->want_subsys, cctx->term, cmd, env_len); 369 370 buffer_init(&cctx->cmd); 371 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 372 free(cmd); 373 cmd = NULL; 374 375 /* Gather fds from client */ 376 for(i = 0; i < 3; i++) { 377 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 378 error("%s: failed to receive fd %d from slave", 379 __func__, i); 380 for (j = 0; j < i; j++) 381 close(new_fd[j]); 382 for (j = 0; j < env_len; j++) 383 free(cctx->env[j]); 384 free(cctx->env); 385 free(cctx->term); 386 buffer_free(&cctx->cmd); 387 free(cctx); 388 389 /* prepare reply */ 390 buffer_put_int(r, MUX_S_FAILURE); 391 buffer_put_int(r, rid); 392 buffer_put_cstring(r, 393 "did not receive file descriptors"); 394 return -1; 395 } 396 } 397 398 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 399 new_fd[0], new_fd[1], new_fd[2]); 400 401 /* XXX support multiple child sessions in future */ 402 if (c->remote_id != -1) { 403 debug2("%s: session already open", __func__); 404 /* prepare reply */ 405 buffer_put_int(r, MUX_S_FAILURE); 406 buffer_put_int(r, rid); 407 buffer_put_cstring(r, "Multiple sessions not supported"); 408 cleanup: 409 close(new_fd[0]); 410 close(new_fd[1]); 411 close(new_fd[2]); 412 free(cctx->term); 413 if (env_len != 0) { 414 for (i = 0; i < env_len; i++) 415 free(cctx->env[i]); 416 free(cctx->env); 417 } 418 buffer_free(&cctx->cmd); 419 free(cctx); 420 return 0; 421 } 422 423 if (options.control_master == SSHCTL_MASTER_ASK || 424 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 425 if (!ask_permission("Allow shared connection to %s? ", host)) { 426 debug2("%s: session refused by user", __func__); 427 /* prepare reply */ 428 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 429 buffer_put_int(r, rid); 430 buffer_put_cstring(r, "Permission denied"); 431 goto cleanup; 432 } 433 } 434 435 /* Try to pick up ttymodes from client before it goes raw */ 436 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 437 error("%s: tcgetattr: %s", __func__, strerror(errno)); 438 439 /* enable nonblocking unless tty */ 440 if (!isatty(new_fd[0])) 441 set_nonblock(new_fd[0]); 442 if (!isatty(new_fd[1])) 443 set_nonblock(new_fd[1]); 444 if (!isatty(new_fd[2])) 445 set_nonblock(new_fd[2]); 446 447 window = CHAN_SES_WINDOW_DEFAULT; 448 packetmax = CHAN_SES_PACKET_DEFAULT; 449 if (cctx->want_tty) { 450 window >>= 1; 451 packetmax >>= 1; 452 } 453 454 nc = channel_new("session", SSH_CHANNEL_OPENING, 455 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 456 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 457 458 nc->ctl_chan = c->self; /* link session -> control channel */ 459 c->remote_id = nc->self; /* link control -> session channel */ 460 461 if (cctx->want_tty && escape_char != 0xffffffff) { 462 channel_register_filter(nc->self, 463 client_simple_escape_filter, NULL, 464 client_filter_cleanup, 465 client_new_escape_filter_ctx((int)escape_char)); 466 } 467 468 debug2("%s: channel_new: %d linked to control channel %d", 469 __func__, nc->self, nc->ctl_chan); 470 471 channel_send_open(nc->self); 472 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 473 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 474 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 475 476 /* reply is deferred, sent by mux_session_confirm */ 477 return 0; 478 } 479 480 static int 481 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 482 { 483 debug2("%s: channel %d: alive check", __func__, c->self); 484 485 /* prepare reply */ 486 buffer_put_int(r, MUX_S_ALIVE); 487 buffer_put_int(r, rid); 488 buffer_put_int(r, (u_int)getpid()); 489 490 return 0; 491 } 492 493 static int 494 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 495 { 496 debug2("%s: channel %d: terminate request", __func__, c->self); 497 498 if (options.control_master == SSHCTL_MASTER_ASK || 499 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 500 if (!ask_permission("Terminate shared connection to %s? ", 501 host)) { 502 debug2("%s: termination refused by user", __func__); 503 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 504 buffer_put_int(r, rid); 505 buffer_put_cstring(r, "Permission denied"); 506 return 0; 507 } 508 } 509 510 quit_pending = 1; 511 buffer_put_int(r, MUX_S_OK); 512 buffer_put_int(r, rid); 513 /* XXX exit happens too soon - message never makes it to client */ 514 return 0; 515 } 516 517 static char * 518 format_forward(u_int ftype, struct Forward *fwd) 519 { 520 char *ret; 521 522 switch (ftype) { 523 case MUX_FWD_LOCAL: 524 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 525 (fwd->listen_path != NULL) ? fwd->listen_path : 526 (fwd->listen_host == NULL) ? 527 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 528 fwd->listen_host, fwd->listen_port, 529 (fwd->connect_path != NULL) ? fwd->connect_path : 530 fwd->connect_host, fwd->connect_port); 531 break; 532 case MUX_FWD_DYNAMIC: 533 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 534 (fwd->listen_host == NULL) ? 535 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 536 fwd->listen_host, fwd->listen_port); 537 break; 538 case MUX_FWD_REMOTE: 539 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 540 (fwd->listen_path != NULL) ? fwd->listen_path : 541 (fwd->listen_host == NULL) ? 542 "LOCALHOST" : fwd->listen_host, 543 fwd->listen_port, 544 (fwd->connect_path != NULL) ? fwd->connect_path : 545 fwd->connect_host, fwd->connect_port); 546 break; 547 default: 548 fatal("%s: unknown forward type %u", __func__, ftype); 549 } 550 return ret; 551 } 552 553 static int 554 compare_host(const char *a, const char *b) 555 { 556 if (a == NULL && b == NULL) 557 return 1; 558 if (a == NULL || b == NULL) 559 return 0; 560 return strcmp(a, b) == 0; 561 } 562 563 static int 564 compare_forward(struct Forward *a, struct Forward *b) 565 { 566 if (!compare_host(a->listen_host, b->listen_host)) 567 return 0; 568 if (!compare_host(a->listen_path, b->listen_path)) 569 return 0; 570 if (a->listen_port != b->listen_port) 571 return 0; 572 if (!compare_host(a->connect_host, b->connect_host)) 573 return 0; 574 if (!compare_host(a->connect_path, b->connect_path)) 575 return 0; 576 if (a->connect_port != b->connect_port) 577 return 0; 578 579 return 1; 580 } 581 582 static void 583 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 584 { 585 struct mux_channel_confirm_ctx *fctx = ctxt; 586 char *failmsg = NULL; 587 struct Forward *rfwd; 588 Channel *c; 589 Buffer out; 590 591 if ((c = channel_by_id(fctx->cid)) == NULL) { 592 /* no channel for reply */ 593 error("%s: unknown channel", __func__); 594 return; 595 } 596 buffer_init(&out); 597 if (fctx->fid >= options.num_remote_forwards) { 598 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 599 goto fail; 600 } 601 rfwd = &options.remote_forwards[fctx->fid]; 602 debug("%s: %s for: listen %d, connect %s:%d", __func__, 603 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 604 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 605 rfwd->connect_host, rfwd->connect_port); 606 if (type == SSH2_MSG_REQUEST_SUCCESS) { 607 if (rfwd->listen_port == 0) { 608 rfwd->allocated_port = packet_get_int(); 609 logit("Allocated port %u for mux remote forward" 610 " to %s:%d", rfwd->allocated_port, 611 rfwd->connect_host, rfwd->connect_port); 612 buffer_put_int(&out, MUX_S_REMOTE_PORT); 613 buffer_put_int(&out, fctx->rid); 614 buffer_put_int(&out, rfwd->allocated_port); 615 channel_update_permitted_opens(rfwd->handle, 616 rfwd->allocated_port); 617 } else { 618 buffer_put_int(&out, MUX_S_OK); 619 buffer_put_int(&out, fctx->rid); 620 } 621 goto out; 622 } else { 623 if (rfwd->listen_port == 0) 624 channel_update_permitted_opens(rfwd->handle, -1); 625 if (rfwd->listen_path != NULL) 626 xasprintf(&failmsg, "remote port forwarding failed for " 627 "listen path %s", rfwd->listen_path); 628 else 629 xasprintf(&failmsg, "remote port forwarding failed for " 630 "listen port %d", rfwd->listen_port); 631 } 632 fail: 633 error("%s: %s", __func__, failmsg); 634 buffer_put_int(&out, MUX_S_FAILURE); 635 buffer_put_int(&out, fctx->rid); 636 buffer_put_cstring(&out, failmsg); 637 free(failmsg); 638 out: 639 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 640 buffer_free(&out); 641 if (c->mux_pause <= 0) 642 fatal("%s: mux_pause %d", __func__, c->mux_pause); 643 c->mux_pause = 0; /* start processing messages again */ 644 } 645 646 static int 647 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 648 { 649 struct Forward fwd; 650 char *fwd_desc = NULL; 651 char *listen_addr, *connect_addr; 652 u_int ftype; 653 u_int lport, cport; 654 int i, ret = 0, freefwd = 1; 655 656 /* XXX - lport/cport check redundant */ 657 if (buffer_get_int_ret(&ftype, m) != 0 || 658 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 659 buffer_get_int_ret(&lport, m) != 0 || 660 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 661 buffer_get_int_ret(&cport, m) != 0 || 662 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 663 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 664 error("%s: malformed message", __func__); 665 ret = -1; 666 goto out; 667 } 668 if (*listen_addr == '\0') { 669 free(listen_addr); 670 listen_addr = NULL; 671 } 672 if (*connect_addr == '\0') { 673 free(connect_addr); 674 connect_addr = NULL; 675 } 676 677 memset(&fwd, 0, sizeof(fwd)); 678 fwd.listen_port = lport; 679 if (fwd.listen_port == PORT_STREAMLOCAL) 680 fwd.listen_path = listen_addr; 681 else 682 fwd.listen_host = listen_addr; 683 fwd.connect_port = cport; 684 if (fwd.connect_port == PORT_STREAMLOCAL) 685 fwd.connect_path = connect_addr; 686 else 687 fwd.connect_host = connect_addr; 688 689 debug2("%s: channel %d: request %s", __func__, c->self, 690 (fwd_desc = format_forward(ftype, &fwd))); 691 692 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 693 ftype != MUX_FWD_DYNAMIC) { 694 logit("%s: invalid forwarding type %u", __func__, ftype); 695 invalid: 696 free(listen_addr); 697 free(connect_addr); 698 buffer_put_int(r, MUX_S_FAILURE); 699 buffer_put_int(r, rid); 700 buffer_put_cstring(r, "Invalid forwarding request"); 701 return 0; 702 } 703 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 704 logit("%s: streamlocal and dynamic forwards " 705 "are mutually exclusive", __func__); 706 goto invalid; 707 } 708 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 709 logit("%s: invalid listen port %u", __func__, 710 fwd.listen_port); 711 goto invalid; 712 } 713 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 714 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 715 logit("%s: invalid connect port %u", __func__, 716 fwd.connect_port); 717 goto invalid; 718 } 719 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 720 logit("%s: missing connect host", __func__); 721 goto invalid; 722 } 723 724 /* Skip forwards that have already been requested */ 725 switch (ftype) { 726 case MUX_FWD_LOCAL: 727 case MUX_FWD_DYNAMIC: 728 for (i = 0; i < options.num_local_forwards; i++) { 729 if (compare_forward(&fwd, 730 options.local_forwards + i)) { 731 exists: 732 debug2("%s: found existing forwarding", 733 __func__); 734 buffer_put_int(r, MUX_S_OK); 735 buffer_put_int(r, rid); 736 goto out; 737 } 738 } 739 break; 740 case MUX_FWD_REMOTE: 741 for (i = 0; i < options.num_remote_forwards; i++) { 742 if (compare_forward(&fwd, 743 options.remote_forwards + i)) { 744 if (fwd.listen_port != 0) 745 goto exists; 746 debug2("%s: found allocated port", 747 __func__); 748 buffer_put_int(r, MUX_S_REMOTE_PORT); 749 buffer_put_int(r, rid); 750 buffer_put_int(r, 751 options.remote_forwards[i].allocated_port); 752 goto out; 753 } 754 } 755 break; 756 } 757 758 if (options.control_master == SSHCTL_MASTER_ASK || 759 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 760 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 761 debug2("%s: forwarding refused by user", __func__); 762 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 763 buffer_put_int(r, rid); 764 buffer_put_cstring(r, "Permission denied"); 765 goto out; 766 } 767 } 768 769 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 770 if (!channel_setup_local_fwd_listener(&fwd, 771 &options.fwd_opts)) { 772 fail: 773 logit("slave-requested %s failed", fwd_desc); 774 buffer_put_int(r, MUX_S_FAILURE); 775 buffer_put_int(r, rid); 776 buffer_put_cstring(r, "Port forwarding failed"); 777 goto out; 778 } 779 add_local_forward(&options, &fwd); 780 freefwd = 0; 781 } else { 782 struct mux_channel_confirm_ctx *fctx; 783 784 fwd.handle = channel_request_remote_forwarding(&fwd); 785 if (fwd.handle < 0) 786 goto fail; 787 add_remote_forward(&options, &fwd); 788 fctx = xcalloc(1, sizeof(*fctx)); 789 fctx->cid = c->self; 790 fctx->rid = rid; 791 fctx->fid = options.num_remote_forwards - 1; 792 client_register_global_confirm(mux_confirm_remote_forward, 793 fctx); 794 freefwd = 0; 795 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 796 /* delayed reply in mux_confirm_remote_forward */ 797 goto out; 798 } 799 buffer_put_int(r, MUX_S_OK); 800 buffer_put_int(r, rid); 801 out: 802 free(fwd_desc); 803 if (freefwd) { 804 free(fwd.listen_host); 805 free(fwd.listen_path); 806 free(fwd.connect_host); 807 free(fwd.connect_path); 808 } 809 return ret; 810 } 811 812 static int 813 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 814 { 815 struct Forward fwd, *found_fwd; 816 char *fwd_desc = NULL; 817 const char *error_reason = NULL; 818 char *listen_addr = NULL, *connect_addr = NULL; 819 u_int ftype; 820 int i, ret = 0; 821 u_int lport, cport; 822 823 if (buffer_get_int_ret(&ftype, m) != 0 || 824 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 825 buffer_get_int_ret(&lport, m) != 0 || 826 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 827 buffer_get_int_ret(&cport, m) != 0 || 828 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 829 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 830 error("%s: malformed message", __func__); 831 ret = -1; 832 goto out; 833 } 834 835 if (*listen_addr == '\0') { 836 free(listen_addr); 837 listen_addr = NULL; 838 } 839 if (*connect_addr == '\0') { 840 free(connect_addr); 841 connect_addr = NULL; 842 } 843 844 memset(&fwd, 0, sizeof(fwd)); 845 fwd.listen_port = lport; 846 if (fwd.listen_port == PORT_STREAMLOCAL) 847 fwd.listen_path = listen_addr; 848 else 849 fwd.listen_host = listen_addr; 850 fwd.connect_port = cport; 851 if (fwd.connect_port == PORT_STREAMLOCAL) 852 fwd.connect_path = connect_addr; 853 else 854 fwd.connect_host = connect_addr; 855 856 debug2("%s: channel %d: request cancel %s", __func__, c->self, 857 (fwd_desc = format_forward(ftype, &fwd))); 858 859 /* make sure this has been requested */ 860 found_fwd = NULL; 861 switch (ftype) { 862 case MUX_FWD_LOCAL: 863 case MUX_FWD_DYNAMIC: 864 for (i = 0; i < options.num_local_forwards; i++) { 865 if (compare_forward(&fwd, 866 options.local_forwards + i)) { 867 found_fwd = options.local_forwards + i; 868 break; 869 } 870 } 871 break; 872 case MUX_FWD_REMOTE: 873 for (i = 0; i < options.num_remote_forwards; i++) { 874 if (compare_forward(&fwd, 875 options.remote_forwards + i)) { 876 found_fwd = options.remote_forwards + i; 877 break; 878 } 879 } 880 break; 881 } 882 883 if (found_fwd == NULL) 884 error_reason = "port not forwarded"; 885 else if (ftype == MUX_FWD_REMOTE) { 886 /* 887 * This shouldn't fail unless we confused the host/port 888 * between options.remote_forwards and permitted_opens. 889 * However, for dynamic allocated listen ports we need 890 * to use the actual listen port. 891 */ 892 if (channel_request_rforward_cancel(found_fwd) == -1) 893 error_reason = "port not in permitted opens"; 894 } else { /* local and dynamic forwards */ 895 /* Ditto */ 896 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 897 &options.fwd_opts) == -1) 898 error_reason = "port not found"; 899 } 900 901 if (error_reason == NULL) { 902 buffer_put_int(r, MUX_S_OK); 903 buffer_put_int(r, rid); 904 905 free(found_fwd->listen_host); 906 free(found_fwd->listen_path); 907 free(found_fwd->connect_host); 908 free(found_fwd->connect_path); 909 found_fwd->listen_host = found_fwd->connect_host = NULL; 910 found_fwd->listen_path = found_fwd->connect_path = NULL; 911 found_fwd->listen_port = found_fwd->connect_port = 0; 912 } else { 913 buffer_put_int(r, MUX_S_FAILURE); 914 buffer_put_int(r, rid); 915 buffer_put_cstring(r, error_reason); 916 } 917 out: 918 free(fwd_desc); 919 free(listen_addr); 920 free(connect_addr); 921 922 return ret; 923 } 924 925 static int 926 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 927 { 928 Channel *nc; 929 char *reserved, *chost; 930 u_int cport, i, j; 931 int new_fd[2]; 932 struct mux_stdio_confirm_ctx *cctx; 933 934 chost = reserved = NULL; 935 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 936 (chost = buffer_get_string_ret(m, NULL)) == NULL || 937 buffer_get_int_ret(&cport, m) != 0) { 938 free(reserved); 939 free(chost); 940 error("%s: malformed message", __func__); 941 return -1; 942 } 943 free(reserved); 944 945 debug2("%s: channel %d: request stdio fwd to %s:%u", 946 __func__, c->self, chost, cport); 947 948 /* Gather fds from client */ 949 for(i = 0; i < 2; i++) { 950 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 951 error("%s: failed to receive fd %d from slave", 952 __func__, i); 953 for (j = 0; j < i; j++) 954 close(new_fd[j]); 955 free(chost); 956 957 /* prepare reply */ 958 buffer_put_int(r, MUX_S_FAILURE); 959 buffer_put_int(r, rid); 960 buffer_put_cstring(r, 961 "did not receive file descriptors"); 962 return -1; 963 } 964 } 965 966 debug3("%s: got fds stdin %d, stdout %d", __func__, 967 new_fd[0], new_fd[1]); 968 969 /* XXX support multiple child sessions in future */ 970 if (c->remote_id != -1) { 971 debug2("%s: session already open", __func__); 972 /* prepare reply */ 973 buffer_put_int(r, MUX_S_FAILURE); 974 buffer_put_int(r, rid); 975 buffer_put_cstring(r, "Multiple sessions not supported"); 976 cleanup: 977 close(new_fd[0]); 978 close(new_fd[1]); 979 free(chost); 980 return 0; 981 } 982 983 if (options.control_master == SSHCTL_MASTER_ASK || 984 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 985 if (!ask_permission("Allow forward to %s:%u? ", 986 chost, cport)) { 987 debug2("%s: stdio fwd refused by user", __func__); 988 /* prepare reply */ 989 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 990 buffer_put_int(r, rid); 991 buffer_put_cstring(r, "Permission denied"); 992 goto cleanup; 993 } 994 } 995 996 /* enable nonblocking unless tty */ 997 if (!isatty(new_fd[0])) 998 set_nonblock(new_fd[0]); 999 if (!isatty(new_fd[1])) 1000 set_nonblock(new_fd[1]); 1001 1002 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1003 1004 nc->ctl_chan = c->self; /* link session -> control channel */ 1005 c->remote_id = nc->self; /* link control -> session channel */ 1006 1007 debug2("%s: channel_new: %d linked to control channel %d", 1008 __func__, nc->self, nc->ctl_chan); 1009 1010 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1011 1012 cctx = xcalloc(1, sizeof(*cctx)); 1013 cctx->rid = rid; 1014 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1015 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1016 1017 /* reply is deferred, sent by mux_session_confirm */ 1018 return 0; 1019 } 1020 1021 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1022 static void 1023 mux_stdio_confirm(int id, int success, void *arg) 1024 { 1025 struct mux_stdio_confirm_ctx *cctx = arg; 1026 Channel *c, *cc; 1027 Buffer reply; 1028 1029 if (cctx == NULL) 1030 fatal("%s: cctx == NULL", __func__); 1031 if ((c = channel_by_id(id)) == NULL) 1032 fatal("%s: no channel for id %d", __func__, id); 1033 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1034 fatal("%s: channel %d lacks control channel %d", __func__, 1035 id, c->ctl_chan); 1036 1037 if (!success) { 1038 debug3("%s: sending failure reply", __func__); 1039 /* prepare reply */ 1040 buffer_init(&reply); 1041 buffer_put_int(&reply, MUX_S_FAILURE); 1042 buffer_put_int(&reply, cctx->rid); 1043 buffer_put_cstring(&reply, "Session open refused by peer"); 1044 goto done; 1045 } 1046 1047 debug3("%s: sending success reply", __func__); 1048 /* prepare reply */ 1049 buffer_init(&reply); 1050 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1051 buffer_put_int(&reply, cctx->rid); 1052 buffer_put_int(&reply, c->self); 1053 1054 done: 1055 /* Send reply */ 1056 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1057 buffer_free(&reply); 1058 1059 if (cc->mux_pause <= 0) 1060 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1061 cc->mux_pause = 0; /* start processing messages again */ 1062 c->open_confirm_ctx = NULL; 1063 free(cctx); 1064 } 1065 1066 static int 1067 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1068 { 1069 debug("%s: channel %d: stop listening", __func__, c->self); 1070 1071 if (options.control_master == SSHCTL_MASTER_ASK || 1072 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1073 if (!ask_permission("Disable further multiplexing on shared " 1074 "connection to %s? ", host)) { 1075 debug2("%s: stop listen refused by user", __func__); 1076 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1077 buffer_put_int(r, rid); 1078 buffer_put_cstring(r, "Permission denied"); 1079 return 0; 1080 } 1081 } 1082 1083 if (mux_listener_channel != NULL) { 1084 channel_free(mux_listener_channel); 1085 client_stop_mux(); 1086 free(options.control_path); 1087 options.control_path = NULL; 1088 mux_listener_channel = NULL; 1089 muxserver_sock = -1; 1090 } 1091 1092 /* prepare reply */ 1093 buffer_put_int(r, MUX_S_OK); 1094 buffer_put_int(r, rid); 1095 1096 return 0; 1097 } 1098 1099 /* Channel callbacks fired on read/write from mux slave fd */ 1100 static int 1101 mux_master_read_cb(Channel *c) 1102 { 1103 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1104 Buffer in, out; 1105 const u_char *ptr; 1106 u_int type, rid, have, i; 1107 int ret = -1; 1108 1109 /* Setup ctx and */ 1110 if (c->mux_ctx == NULL) { 1111 state = xcalloc(1, sizeof(*state)); 1112 c->mux_ctx = state; 1113 channel_register_cleanup(c->self, 1114 mux_master_control_cleanup_cb, 0); 1115 1116 /* Send hello */ 1117 buffer_init(&out); 1118 buffer_put_int(&out, MUX_MSG_HELLO); 1119 buffer_put_int(&out, SSHMUX_VER); 1120 /* no extensions */ 1121 buffer_put_string(&c->output, buffer_ptr(&out), 1122 buffer_len(&out)); 1123 buffer_free(&out); 1124 debug3("%s: channel %d: hello sent", __func__, c->self); 1125 return 0; 1126 } 1127 1128 buffer_init(&in); 1129 buffer_init(&out); 1130 1131 /* Channel code ensures that we receive whole packets */ 1132 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1133 malf: 1134 error("%s: malformed message", __func__); 1135 goto out; 1136 } 1137 buffer_append(&in, ptr, have); 1138 1139 if (buffer_get_int_ret(&type, &in) != 0) 1140 goto malf; 1141 debug3("%s: channel %d packet type 0x%08x len %u", 1142 __func__, c->self, type, buffer_len(&in)); 1143 1144 if (type == MUX_MSG_HELLO) 1145 rid = 0; 1146 else { 1147 if (!state->hello_rcvd) { 1148 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1149 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1150 goto out; 1151 } 1152 if (buffer_get_int_ret(&rid, &in) != 0) 1153 goto malf; 1154 } 1155 1156 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1157 if (type == mux_master_handlers[i].type) { 1158 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1159 break; 1160 } 1161 } 1162 if (mux_master_handlers[i].handler == NULL) { 1163 error("%s: unsupported mux message 0x%08x", __func__, type); 1164 buffer_put_int(&out, MUX_S_FAILURE); 1165 buffer_put_int(&out, rid); 1166 buffer_put_cstring(&out, "unsupported request"); 1167 ret = 0; 1168 } 1169 /* Enqueue reply packet */ 1170 if (buffer_len(&out) != 0) { 1171 buffer_put_string(&c->output, buffer_ptr(&out), 1172 buffer_len(&out)); 1173 } 1174 out: 1175 buffer_free(&in); 1176 buffer_free(&out); 1177 return ret; 1178 } 1179 1180 void 1181 mux_exit_message(Channel *c, int exitval) 1182 { 1183 Buffer m; 1184 Channel *mux_chan; 1185 1186 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1187 exitval); 1188 1189 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1190 fatal("%s: channel %d missing mux channel %d", 1191 __func__, c->self, c->ctl_chan); 1192 1193 /* Append exit message packet to control socket output queue */ 1194 buffer_init(&m); 1195 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1196 buffer_put_int(&m, c->self); 1197 buffer_put_int(&m, exitval); 1198 1199 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1200 buffer_free(&m); 1201 } 1202 1203 void 1204 mux_tty_alloc_failed(Channel *c) 1205 { 1206 Buffer m; 1207 Channel *mux_chan; 1208 1209 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1210 1211 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1212 fatal("%s: channel %d missing mux channel %d", 1213 __func__, c->self, c->ctl_chan); 1214 1215 /* Append exit message packet to control socket output queue */ 1216 buffer_init(&m); 1217 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1218 buffer_put_int(&m, c->self); 1219 1220 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1221 buffer_free(&m); 1222 } 1223 1224 /* Prepare a mux master to listen on a Unix domain socket. */ 1225 void 1226 muxserver_listen(void) 1227 { 1228 mode_t old_umask; 1229 char *orig_control_path = options.control_path; 1230 char rbuf[16+1]; 1231 u_int i, r; 1232 int oerrno; 1233 1234 if (options.control_path == NULL || 1235 options.control_master == SSHCTL_MASTER_NO) 1236 return; 1237 1238 debug("setting up multiplex master socket"); 1239 1240 /* 1241 * Use a temporary path before listen so we can pseudo-atomically 1242 * establish the listening socket in its final location to avoid 1243 * other processes racing in between bind() and listen() and hitting 1244 * an unready socket. 1245 */ 1246 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1247 r = arc4random_uniform(26+26+10); 1248 rbuf[i] = (r < 26) ? 'a' + r : 1249 (r < 26*2) ? 'A' + r - 26 : 1250 '0' + r - 26 - 26; 1251 } 1252 rbuf[sizeof(rbuf) - 1] = '\0'; 1253 options.control_path = NULL; 1254 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1255 debug3("%s: temporary control path %s", __func__, options.control_path); 1256 1257 old_umask = umask(0177); 1258 muxserver_sock = unix_listener(options.control_path, 64, 0); 1259 oerrno = errno; 1260 umask(old_umask); 1261 if (muxserver_sock < 0) { 1262 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1263 error("ControlSocket %s already exists, " 1264 "disabling multiplexing", options.control_path); 1265 disable_mux_master: 1266 if (muxserver_sock != -1) { 1267 close(muxserver_sock); 1268 muxserver_sock = -1; 1269 } 1270 free(orig_control_path); 1271 free(options.control_path); 1272 options.control_path = NULL; 1273 options.control_master = SSHCTL_MASTER_NO; 1274 return; 1275 } else { 1276 /* unix_listener() logs the error */ 1277 cleanup_exit(255); 1278 } 1279 } 1280 1281 /* Now atomically "move" the mux socket into position */ 1282 if (link(options.control_path, orig_control_path) != 0) { 1283 if (errno != EEXIST) { 1284 fatal("%s: link mux listener %s => %s: %s", __func__, 1285 options.control_path, orig_control_path, 1286 strerror(errno)); 1287 } 1288 error("ControlSocket %s already exists, disabling multiplexing", 1289 orig_control_path); 1290 unlink(options.control_path); 1291 goto disable_mux_master; 1292 } 1293 unlink(options.control_path); 1294 free(options.control_path); 1295 options.control_path = orig_control_path; 1296 1297 set_nonblock(muxserver_sock); 1298 1299 mux_listener_channel = channel_new("mux listener", 1300 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1301 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1302 0, options.control_path, 1); 1303 mux_listener_channel->mux_rcb = mux_master_read_cb; 1304 debug3("%s: mux listener channel %d fd %d", __func__, 1305 mux_listener_channel->self, mux_listener_channel->sock); 1306 } 1307 1308 /* Callback on open confirmation in mux master for a mux client session. */ 1309 static void 1310 mux_session_confirm(int id, int success, void *arg) 1311 { 1312 struct mux_session_confirm_ctx *cctx = arg; 1313 const char *display; 1314 Channel *c, *cc; 1315 int i; 1316 Buffer reply; 1317 1318 if (cctx == NULL) 1319 fatal("%s: cctx == NULL", __func__); 1320 if ((c = channel_by_id(id)) == NULL) 1321 fatal("%s: no channel for id %d", __func__, id); 1322 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1323 fatal("%s: channel %d lacks control channel %d", __func__, 1324 id, c->ctl_chan); 1325 1326 if (!success) { 1327 debug3("%s: sending failure reply", __func__); 1328 /* prepare reply */ 1329 buffer_init(&reply); 1330 buffer_put_int(&reply, MUX_S_FAILURE); 1331 buffer_put_int(&reply, cctx->rid); 1332 buffer_put_cstring(&reply, "Session open refused by peer"); 1333 goto done; 1334 } 1335 1336 display = getenv("DISPLAY"); 1337 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1338 char *proto, *data; 1339 1340 /* Get reasonable local authentication information. */ 1341 client_x11_get_proto(display, options.xauth_location, 1342 options.forward_x11_trusted, options.forward_x11_timeout, 1343 &proto, &data); 1344 /* Request forwarding with authentication spoofing. */ 1345 debug("Requesting X11 forwarding with authentication " 1346 "spoofing."); 1347 x11_request_forwarding_with_spoofing(id, display, proto, 1348 data, 1); 1349 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1350 /* XXX exit_on_forward_failure */ 1351 } 1352 1353 if (cctx->want_agent_fwd && options.forward_agent) { 1354 debug("Requesting authentication agent forwarding."); 1355 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1356 packet_send(); 1357 } 1358 1359 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1360 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1361 1362 debug3("%s: sending success reply", __func__); 1363 /* prepare reply */ 1364 buffer_init(&reply); 1365 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1366 buffer_put_int(&reply, cctx->rid); 1367 buffer_put_int(&reply, c->self); 1368 1369 done: 1370 /* Send reply */ 1371 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1372 buffer_free(&reply); 1373 1374 if (cc->mux_pause <= 0) 1375 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1376 cc->mux_pause = 0; /* start processing messages again */ 1377 c->open_confirm_ctx = NULL; 1378 buffer_free(&cctx->cmd); 1379 free(cctx->term); 1380 if (cctx->env != NULL) { 1381 for (i = 0; cctx->env[i] != NULL; i++) 1382 free(cctx->env[i]); 1383 free(cctx->env); 1384 } 1385 free(cctx); 1386 } 1387 1388 /* ** Multiplexing client support */ 1389 1390 /* Exit signal handler */ 1391 static void 1392 control_client_sighandler(int signo) 1393 { 1394 muxclient_terminate = signo; 1395 } 1396 1397 /* 1398 * Relay signal handler - used to pass some signals from mux client to 1399 * mux master. 1400 */ 1401 static void 1402 control_client_sigrelay(int signo) 1403 { 1404 int save_errno = errno; 1405 1406 if (muxserver_pid > 1) 1407 kill(muxserver_pid, signo); 1408 1409 errno = save_errno; 1410 } 1411 1412 static int 1413 mux_client_read(int fd, Buffer *b, u_int need) 1414 { 1415 u_int have; 1416 ssize_t len; 1417 u_char *p; 1418 struct pollfd pfd; 1419 1420 pfd.fd = fd; 1421 pfd.events = POLLIN; 1422 p = buffer_append_space(b, need); 1423 for (have = 0; have < need; ) { 1424 if (muxclient_terminate) { 1425 errno = EINTR; 1426 return -1; 1427 } 1428 len = read(fd, p + have, need - have); 1429 if (len < 0) { 1430 switch (errno) { 1431 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1432 case EWOULDBLOCK: 1433 #endif 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 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1479 case EWOULDBLOCK: 1480 #endif 1481 case EAGAIN: 1482 (void)poll(&pfd, 1, -1); 1483 /* FALLTHROUGH */ 1484 case EINTR: 1485 continue; 1486 default: 1487 oerrno = errno; 1488 buffer_free(&queue); 1489 errno = oerrno; 1490 return -1; 1491 } 1492 } 1493 if (len == 0) { 1494 buffer_free(&queue); 1495 errno = EPIPE; 1496 return -1; 1497 } 1498 have += (u_int)len; 1499 } 1500 buffer_free(&queue); 1501 return 0; 1502 } 1503 1504 static int 1505 mux_client_read_packet(int fd, Buffer *m) 1506 { 1507 Buffer queue; 1508 u_int need, have; 1509 const u_char *ptr; 1510 int oerrno; 1511 1512 buffer_init(&queue); 1513 if (mux_client_read(fd, &queue, 4) != 0) { 1514 if ((oerrno = errno) == EPIPE) 1515 debug3("%s: read header failed: %s", __func__, 1516 strerror(errno)); 1517 buffer_free(&queue); 1518 errno = oerrno; 1519 return -1; 1520 } 1521 need = get_u32(buffer_ptr(&queue)); 1522 if (mux_client_read(fd, &queue, need) != 0) { 1523 oerrno = errno; 1524 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1525 buffer_free(&queue); 1526 errno = oerrno; 1527 return -1; 1528 } 1529 ptr = buffer_get_string_ptr(&queue, &have); 1530 buffer_append(m, ptr, have); 1531 buffer_free(&queue); 1532 return 0; 1533 } 1534 1535 static int 1536 mux_client_hello_exchange(int fd) 1537 { 1538 Buffer m; 1539 u_int type, ver; 1540 1541 buffer_init(&m); 1542 buffer_put_int(&m, MUX_MSG_HELLO); 1543 buffer_put_int(&m, SSHMUX_VER); 1544 /* no extensions */ 1545 1546 if (mux_client_write_packet(fd, &m) != 0) 1547 fatal("%s: write packet: %s", __func__, strerror(errno)); 1548 1549 buffer_clear(&m); 1550 1551 /* Read their HELLO */ 1552 if (mux_client_read_packet(fd, &m) != 0) { 1553 buffer_free(&m); 1554 return -1; 1555 } 1556 1557 type = buffer_get_int(&m); 1558 if (type != MUX_MSG_HELLO) 1559 fatal("%s: expected HELLO (%u) received %u", 1560 __func__, MUX_MSG_HELLO, type); 1561 ver = buffer_get_int(&m); 1562 if (ver != SSHMUX_VER) 1563 fatal("Unsupported multiplexing protocol version %d " 1564 "(expected %d)", ver, SSHMUX_VER); 1565 debug2("%s: master version %u", __func__, ver); 1566 /* No extensions are presently defined */ 1567 while (buffer_len(&m) > 0) { 1568 char *name = buffer_get_string(&m, NULL); 1569 char *value = buffer_get_string(&m, NULL); 1570 1571 debug2("Unrecognised master extension \"%s\"", name); 1572 free(name); 1573 free(value); 1574 } 1575 buffer_free(&m); 1576 return 0; 1577 } 1578 1579 static u_int 1580 mux_client_request_alive(int fd) 1581 { 1582 Buffer m; 1583 char *e; 1584 u_int pid, type, rid; 1585 1586 debug3("%s: entering", __func__); 1587 1588 buffer_init(&m); 1589 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1590 buffer_put_int(&m, muxclient_request_id); 1591 1592 if (mux_client_write_packet(fd, &m) != 0) 1593 fatal("%s: write packet: %s", __func__, strerror(errno)); 1594 1595 buffer_clear(&m); 1596 1597 /* Read their reply */ 1598 if (mux_client_read_packet(fd, &m) != 0) { 1599 buffer_free(&m); 1600 return 0; 1601 } 1602 1603 type = buffer_get_int(&m); 1604 if (type != MUX_S_ALIVE) { 1605 e = buffer_get_string(&m, NULL); 1606 fatal("%s: master returned error: %s", __func__, e); 1607 } 1608 1609 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1610 fatal("%s: out of sequence reply: my id %u theirs %u", 1611 __func__, muxclient_request_id, rid); 1612 pid = buffer_get_int(&m); 1613 buffer_free(&m); 1614 1615 debug3("%s: done pid = %u", __func__, pid); 1616 1617 muxclient_request_id++; 1618 1619 return pid; 1620 } 1621 1622 static void 1623 mux_client_request_terminate(int fd) 1624 { 1625 Buffer m; 1626 char *e; 1627 u_int type, rid; 1628 1629 debug3("%s: entering", __func__); 1630 1631 buffer_init(&m); 1632 buffer_put_int(&m, MUX_C_TERMINATE); 1633 buffer_put_int(&m, muxclient_request_id); 1634 1635 if (mux_client_write_packet(fd, &m) != 0) 1636 fatal("%s: write packet: %s", __func__, strerror(errno)); 1637 1638 buffer_clear(&m); 1639 1640 /* Read their reply */ 1641 if (mux_client_read_packet(fd, &m) != 0) { 1642 /* Remote end exited already */ 1643 if (errno == EPIPE) { 1644 buffer_free(&m); 1645 return; 1646 } 1647 fatal("%s: read from master failed: %s", 1648 __func__, strerror(errno)); 1649 } 1650 1651 type = buffer_get_int(&m); 1652 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1653 fatal("%s: out of sequence reply: my id %u theirs %u", 1654 __func__, muxclient_request_id, rid); 1655 switch (type) { 1656 case MUX_S_OK: 1657 break; 1658 case MUX_S_PERMISSION_DENIED: 1659 e = buffer_get_string(&m, NULL); 1660 fatal("Master refused termination request: %s", e); 1661 case MUX_S_FAILURE: 1662 e = buffer_get_string(&m, NULL); 1663 fatal("%s: termination request failed: %s", __func__, e); 1664 default: 1665 fatal("%s: unexpected response from master 0x%08x", 1666 __func__, type); 1667 } 1668 buffer_free(&m); 1669 muxclient_request_id++; 1670 } 1671 1672 static int 1673 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1674 { 1675 Buffer m; 1676 char *e, *fwd_desc; 1677 u_int type, rid; 1678 1679 fwd_desc = format_forward(ftype, fwd); 1680 debug("Requesting %s %s", 1681 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1682 free(fwd_desc); 1683 1684 buffer_init(&m); 1685 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1686 buffer_put_int(&m, muxclient_request_id); 1687 buffer_put_int(&m, ftype); 1688 if (fwd->listen_path != NULL) { 1689 buffer_put_cstring(&m, fwd->listen_path); 1690 } else { 1691 buffer_put_cstring(&m, 1692 fwd->listen_host == NULL ? "" : fwd->listen_host); 1693 } 1694 buffer_put_int(&m, fwd->listen_port); 1695 if (fwd->connect_path != NULL) { 1696 buffer_put_cstring(&m, fwd->connect_path); 1697 } else { 1698 buffer_put_cstring(&m, 1699 fwd->connect_host == NULL ? "" : fwd->connect_host); 1700 } 1701 buffer_put_int(&m, fwd->connect_port); 1702 1703 if (mux_client_write_packet(fd, &m) != 0) 1704 fatal("%s: write packet: %s", __func__, strerror(errno)); 1705 1706 buffer_clear(&m); 1707 1708 /* Read their reply */ 1709 if (mux_client_read_packet(fd, &m) != 0) { 1710 buffer_free(&m); 1711 return -1; 1712 } 1713 1714 type = buffer_get_int(&m); 1715 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1716 fatal("%s: out of sequence reply: my id %u theirs %u", 1717 __func__, muxclient_request_id, rid); 1718 switch (type) { 1719 case MUX_S_OK: 1720 break; 1721 case MUX_S_REMOTE_PORT: 1722 if (cancel_flag) 1723 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1724 fwd->allocated_port = buffer_get_int(&m); 1725 logit("Allocated port %u for remote forward to %s:%d", 1726 fwd->allocated_port, 1727 fwd->connect_host ? fwd->connect_host : "", 1728 fwd->connect_port); 1729 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1730 fprintf(stdout, "%u\n", fwd->allocated_port); 1731 break; 1732 case MUX_S_PERMISSION_DENIED: 1733 e = buffer_get_string(&m, NULL); 1734 buffer_free(&m); 1735 error("Master refused forwarding request: %s", e); 1736 return -1; 1737 case MUX_S_FAILURE: 1738 e = buffer_get_string(&m, NULL); 1739 buffer_free(&m); 1740 error("%s: forwarding request failed: %s", __func__, e); 1741 return -1; 1742 default: 1743 fatal("%s: unexpected response from master 0x%08x", 1744 __func__, type); 1745 } 1746 buffer_free(&m); 1747 1748 muxclient_request_id++; 1749 return 0; 1750 } 1751 1752 static int 1753 mux_client_forwards(int fd, int cancel_flag) 1754 { 1755 int i, ret = 0; 1756 1757 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1758 cancel_flag ? "cancel" : "request", 1759 options.num_local_forwards, options.num_remote_forwards); 1760 1761 /* XXX ExitOnForwardingFailure */ 1762 for (i = 0; i < options.num_local_forwards; i++) { 1763 if (mux_client_forward(fd, cancel_flag, 1764 options.local_forwards[i].connect_port == 0 ? 1765 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1766 options.local_forwards + i) != 0) 1767 ret = -1; 1768 } 1769 for (i = 0; i < options.num_remote_forwards; i++) { 1770 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1771 options.remote_forwards + i) != 0) 1772 ret = -1; 1773 } 1774 return ret; 1775 } 1776 1777 static int 1778 mux_client_request_session(int fd) 1779 { 1780 Buffer m; 1781 char *e, *term; 1782 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1783 extern char **environ; 1784 int devnull, rawmode; 1785 1786 debug3("%s: entering", __func__); 1787 1788 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1789 error("%s: master alive request failed", __func__); 1790 return -1; 1791 } 1792 1793 signal(SIGPIPE, SIG_IGN); 1794 1795 if (stdin_null_flag) { 1796 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1797 fatal("open(/dev/null): %s", strerror(errno)); 1798 if (dup2(devnull, STDIN_FILENO) == -1) 1799 fatal("dup2: %s", strerror(errno)); 1800 if (devnull > STDERR_FILENO) 1801 close(devnull); 1802 } 1803 1804 term = getenv("TERM"); 1805 1806 buffer_init(&m); 1807 buffer_put_int(&m, MUX_C_NEW_SESSION); 1808 buffer_put_int(&m, muxclient_request_id); 1809 buffer_put_cstring(&m, ""); /* reserved */ 1810 buffer_put_int(&m, tty_flag); 1811 buffer_put_int(&m, options.forward_x11); 1812 buffer_put_int(&m, options.forward_agent); 1813 buffer_put_int(&m, subsystem_flag); 1814 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1815 0xffffffff : (u_int)options.escape_char); 1816 buffer_put_cstring(&m, term == NULL ? "" : term); 1817 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1818 1819 if (options.num_send_env > 0 && environ != NULL) { 1820 /* Pass environment */ 1821 for (i = 0; environ[i] != NULL; i++) { 1822 if (env_permitted(environ[i])) { 1823 buffer_put_cstring(&m, environ[i]); 1824 } 1825 } 1826 } 1827 1828 if (mux_client_write_packet(fd, &m) != 0) 1829 fatal("%s: write packet: %s", __func__, strerror(errno)); 1830 1831 /* Send the stdio file descriptors */ 1832 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1833 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1834 mm_send_fd(fd, STDERR_FILENO) == -1) 1835 fatal("%s: send fds failed", __func__); 1836 1837 debug3("%s: session request sent", __func__); 1838 1839 /* Read their reply */ 1840 buffer_clear(&m); 1841 if (mux_client_read_packet(fd, &m) != 0) { 1842 error("%s: read from master failed: %s", 1843 __func__, strerror(errno)); 1844 buffer_free(&m); 1845 return -1; 1846 } 1847 1848 type = buffer_get_int(&m); 1849 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1850 fatal("%s: out of sequence reply: my id %u theirs %u", 1851 __func__, muxclient_request_id, rid); 1852 switch (type) { 1853 case MUX_S_SESSION_OPENED: 1854 sid = buffer_get_int(&m); 1855 debug("%s: master session id: %u", __func__, sid); 1856 break; 1857 case MUX_S_PERMISSION_DENIED: 1858 e = buffer_get_string(&m, NULL); 1859 buffer_free(&m); 1860 error("Master refused session request: %s", e); 1861 return -1; 1862 case MUX_S_FAILURE: 1863 e = buffer_get_string(&m, NULL); 1864 buffer_free(&m); 1865 error("%s: session request failed: %s", __func__, e); 1866 return -1; 1867 default: 1868 buffer_free(&m); 1869 error("%s: unexpected response from master 0x%08x", 1870 __func__, type); 1871 return -1; 1872 } 1873 muxclient_request_id++; 1874 1875 signal(SIGHUP, control_client_sighandler); 1876 signal(SIGINT, control_client_sighandler); 1877 signal(SIGTERM, control_client_sighandler); 1878 signal(SIGWINCH, control_client_sigrelay); 1879 1880 rawmode = tty_flag; 1881 if (tty_flag) 1882 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1883 1884 /* 1885 * Stick around until the controlee closes the client_fd. 1886 * Before it does, it is expected to write an exit message. 1887 * This process must read the value and wait for the closure of 1888 * the client_fd; if this one closes early, the multiplex master will 1889 * terminate early too (possibly losing data). 1890 */ 1891 for (exitval = 255, exitval_seen = 0;;) { 1892 buffer_clear(&m); 1893 if (mux_client_read_packet(fd, &m) != 0) 1894 break; 1895 type = buffer_get_int(&m); 1896 switch (type) { 1897 case MUX_S_TTY_ALLOC_FAIL: 1898 if ((esid = buffer_get_int(&m)) != sid) 1899 fatal("%s: tty alloc fail on unknown session: " 1900 "my id %u theirs %u", 1901 __func__, sid, esid); 1902 leave_raw_mode(options.request_tty == 1903 REQUEST_TTY_FORCE); 1904 rawmode = 0; 1905 continue; 1906 case MUX_S_EXIT_MESSAGE: 1907 if ((esid = buffer_get_int(&m)) != sid) 1908 fatal("%s: exit on unknown session: " 1909 "my id %u theirs %u", 1910 __func__, sid, esid); 1911 if (exitval_seen) 1912 fatal("%s: exitval sent twice", __func__); 1913 exitval = buffer_get_int(&m); 1914 exitval_seen = 1; 1915 continue; 1916 default: 1917 e = buffer_get_string(&m, NULL); 1918 fatal("%s: master returned error: %s", __func__, e); 1919 } 1920 } 1921 1922 close(fd); 1923 if (rawmode) 1924 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1925 1926 if (muxclient_terminate) { 1927 debug2("Exiting on signal %d", muxclient_terminate); 1928 exitval = 255; 1929 } else if (!exitval_seen) { 1930 debug2("Control master terminated unexpectedly"); 1931 exitval = 255; 1932 } else 1933 debug2("Received exit status from master %d", exitval); 1934 1935 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1936 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1937 1938 exit(exitval); 1939 } 1940 1941 static int 1942 mux_client_request_stdio_fwd(int fd) 1943 { 1944 Buffer m; 1945 char *e; 1946 u_int type, rid, sid; 1947 int devnull; 1948 1949 debug3("%s: entering", __func__); 1950 1951 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1952 error("%s: master alive request failed", __func__); 1953 return -1; 1954 } 1955 1956 signal(SIGPIPE, SIG_IGN); 1957 1958 if (stdin_null_flag) { 1959 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1960 fatal("open(/dev/null): %s", strerror(errno)); 1961 if (dup2(devnull, STDIN_FILENO) == -1) 1962 fatal("dup2: %s", strerror(errno)); 1963 if (devnull > STDERR_FILENO) 1964 close(devnull); 1965 } 1966 1967 buffer_init(&m); 1968 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1969 buffer_put_int(&m, muxclient_request_id); 1970 buffer_put_cstring(&m, ""); /* reserved */ 1971 buffer_put_cstring(&m, stdio_forward_host); 1972 buffer_put_int(&m, stdio_forward_port); 1973 1974 if (mux_client_write_packet(fd, &m) != 0) 1975 fatal("%s: write packet: %s", __func__, strerror(errno)); 1976 1977 /* Send the stdio file descriptors */ 1978 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1979 mm_send_fd(fd, STDOUT_FILENO) == -1) 1980 fatal("%s: send fds failed", __func__); 1981 1982 debug3("%s: stdio forward request sent", __func__); 1983 1984 /* Read their reply */ 1985 buffer_clear(&m); 1986 1987 if (mux_client_read_packet(fd, &m) != 0) { 1988 error("%s: read from master failed: %s", 1989 __func__, strerror(errno)); 1990 buffer_free(&m); 1991 return -1; 1992 } 1993 1994 type = buffer_get_int(&m); 1995 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1996 fatal("%s: out of sequence reply: my id %u theirs %u", 1997 __func__, muxclient_request_id, rid); 1998 switch (type) { 1999 case MUX_S_SESSION_OPENED: 2000 sid = buffer_get_int(&m); 2001 debug("%s: master session id: %u", __func__, sid); 2002 break; 2003 case MUX_S_PERMISSION_DENIED: 2004 e = buffer_get_string(&m, NULL); 2005 buffer_free(&m); 2006 fatal("Master refused stdio forwarding request: %s", e); 2007 case MUX_S_FAILURE: 2008 e = buffer_get_string(&m, NULL); 2009 buffer_free(&m); 2010 fatal("Stdio forwarding request failed: %s", e); 2011 default: 2012 buffer_free(&m); 2013 error("%s: unexpected response from master 0x%08x", 2014 __func__, type); 2015 return -1; 2016 } 2017 muxclient_request_id++; 2018 2019 signal(SIGHUP, control_client_sighandler); 2020 signal(SIGINT, control_client_sighandler); 2021 signal(SIGTERM, control_client_sighandler); 2022 signal(SIGWINCH, control_client_sigrelay); 2023 2024 /* 2025 * Stick around until the controlee closes the client_fd. 2026 */ 2027 buffer_clear(&m); 2028 if (mux_client_read_packet(fd, &m) != 0) { 2029 if (errno == EPIPE || 2030 (errno == EINTR && muxclient_terminate != 0)) 2031 return 0; 2032 fatal("%s: mux_client_read_packet: %s", 2033 __func__, strerror(errno)); 2034 } 2035 fatal("%s: master returned unexpected message %u", __func__, type); 2036 } 2037 2038 static void 2039 mux_client_request_stop_listening(int fd) 2040 { 2041 Buffer m; 2042 char *e; 2043 u_int type, rid; 2044 2045 debug3("%s: entering", __func__); 2046 2047 buffer_init(&m); 2048 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2049 buffer_put_int(&m, muxclient_request_id); 2050 2051 if (mux_client_write_packet(fd, &m) != 0) 2052 fatal("%s: write packet: %s", __func__, strerror(errno)); 2053 2054 buffer_clear(&m); 2055 2056 /* Read their reply */ 2057 if (mux_client_read_packet(fd, &m) != 0) 2058 fatal("%s: read from master failed: %s", 2059 __func__, strerror(errno)); 2060 2061 type = buffer_get_int(&m); 2062 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2063 fatal("%s: out of sequence reply: my id %u theirs %u", 2064 __func__, muxclient_request_id, rid); 2065 switch (type) { 2066 case MUX_S_OK: 2067 break; 2068 case MUX_S_PERMISSION_DENIED: 2069 e = buffer_get_string(&m, NULL); 2070 fatal("Master refused stop listening request: %s", e); 2071 case MUX_S_FAILURE: 2072 e = buffer_get_string(&m, NULL); 2073 fatal("%s: stop listening request failed: %s", __func__, e); 2074 default: 2075 fatal("%s: unexpected response from master 0x%08x", 2076 __func__, type); 2077 } 2078 buffer_free(&m); 2079 muxclient_request_id++; 2080 } 2081 2082 /* Multiplex client main loop. */ 2083 void 2084 muxclient(const char *path) 2085 { 2086 struct sockaddr_un addr; 2087 socklen_t sun_len; 2088 int sock; 2089 u_int pid; 2090 2091 if (muxclient_command == 0) { 2092 if (stdio_forward_host != NULL) 2093 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2094 else 2095 muxclient_command = SSHMUX_COMMAND_OPEN; 2096 } 2097 2098 switch (options.control_master) { 2099 case SSHCTL_MASTER_AUTO: 2100 case SSHCTL_MASTER_AUTO_ASK: 2101 debug("auto-mux: Trying existing master"); 2102 /* FALLTHROUGH */ 2103 case SSHCTL_MASTER_NO: 2104 break; 2105 default: 2106 return; 2107 } 2108 2109 memset(&addr, '\0', sizeof(addr)); 2110 addr.sun_family = AF_UNIX; 2111 sun_len = offsetof(struct sockaddr_un, sun_path) + 2112 strlen(path) + 1; 2113 2114 if (strlcpy(addr.sun_path, path, 2115 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2116 fatal("ControlPath too long"); 2117 2118 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2119 fatal("%s socket(): %s", __func__, strerror(errno)); 2120 2121 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2122 switch (muxclient_command) { 2123 case SSHMUX_COMMAND_OPEN: 2124 case SSHMUX_COMMAND_STDIO_FWD: 2125 break; 2126 default: 2127 fatal("Control socket connect(%.100s): %s", path, 2128 strerror(errno)); 2129 } 2130 if (errno == ECONNREFUSED && 2131 options.control_master != SSHCTL_MASTER_NO) { 2132 debug("Stale control socket %.100s, unlinking", path); 2133 unlink(path); 2134 } else if (errno == ENOENT) { 2135 debug("Control socket \"%.100s\" does not exist", path); 2136 } else { 2137 error("Control socket connect(%.100s): %s", path, 2138 strerror(errno)); 2139 } 2140 close(sock); 2141 return; 2142 } 2143 set_nonblock(sock); 2144 2145 if (mux_client_hello_exchange(sock) != 0) { 2146 error("%s: master hello exchange failed", __func__); 2147 close(sock); 2148 return; 2149 } 2150 2151 switch (muxclient_command) { 2152 case SSHMUX_COMMAND_ALIVE_CHECK: 2153 if ((pid = mux_client_request_alive(sock)) == 0) 2154 fatal("%s: master alive check failed", __func__); 2155 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2156 exit(0); 2157 case SSHMUX_COMMAND_TERMINATE: 2158 mux_client_request_terminate(sock); 2159 fprintf(stderr, "Exit request sent.\r\n"); 2160 exit(0); 2161 case SSHMUX_COMMAND_FORWARD: 2162 if (mux_client_forwards(sock, 0) != 0) 2163 fatal("%s: master forward request failed", __func__); 2164 exit(0); 2165 case SSHMUX_COMMAND_OPEN: 2166 if (mux_client_forwards(sock, 0) != 0) { 2167 error("%s: master forward request failed", __func__); 2168 return; 2169 } 2170 mux_client_request_session(sock); 2171 return; 2172 case SSHMUX_COMMAND_STDIO_FWD: 2173 mux_client_request_stdio_fwd(sock); 2174 exit(0); 2175 case SSHMUX_COMMAND_STOP: 2176 mux_client_request_stop_listening(sock); 2177 fprintf(stderr, "Stop listening request sent.\r\n"); 2178 exit(0); 2179 case SSHMUX_COMMAND_CANCEL_FWD: 2180 if (mux_client_forwards(sock, 1) != 0) 2181 error("%s: master cancel forward request failed", 2182 __func__); 2183 exit(0); 2184 default: 2185 fatal("unrecognised muxclient_command %d", muxclient_command); 2186 } 2187 } 2188