1 /* $NetBSD: mux.c,v 1.15 2016/03/11 01:55:00 christos Exp $ */ 2 /* $OpenBSD: mux.c,v 1.58 2016/01/13 23:04:47 djm Exp $ */ 3 4 /* 5 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 /* ssh session multiplexing support */ 21 22 /* 23 * TODO: 24 * - Better signalling from master to slave, especially passing of 25 * error messages 26 * - Better fall-back from mux slave error to new connection. 27 * - ExitOnForwardingFailure 28 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 29 * - Support ~^Z in mux slaves. 30 * - Inspect or control sessions in master. 31 * - If we ever support the "signal" channel request, send signals on 32 * sessions in master. 33 */ 34 35 #include "includes.h" 36 __RCSID("$NetBSD: mux.c,v 1.15 2016/03/11 01:55:00 christos Exp $"); 37 #include <sys/types.h> 38 #include <sys/queue.h> 39 #include <sys/stat.h> 40 #include <sys/socket.h> 41 #include <sys/un.h> 42 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <poll.h> 46 #include <signal.h> 47 #include <stdarg.h> 48 #include <stddef.h> 49 #include <stdlib.h> 50 #include <stdio.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <util.h> 54 #include <paths.h> 55 56 #include "atomicio.h" 57 #include "xmalloc.h" 58 #include "log.h" 59 #include "ssh.h" 60 #include "ssh2.h" 61 #include "pathnames.h" 62 #include "misc.h" 63 #include "match.h" 64 #include "buffer.h" 65 #include "channels.h" 66 #include "msg.h" 67 #include "packet.h" 68 #include "monitor_fdpass.h" 69 #include "sshpty.h" 70 #include "key.h" 71 #include "readconf.h" 72 #include "clientloop.h" 73 74 /* from ssh.c */ 75 extern int tty_flag; 76 extern Options options; 77 extern int stdin_null_flag; 78 extern char *host; 79 extern int subsystem_flag; 80 extern Buffer command; 81 extern volatile sig_atomic_t quit_pending; 82 extern char *stdio_forward_host; 83 extern int stdio_forward_port; 84 85 /* Context for session open confirmation callback */ 86 struct mux_session_confirm_ctx { 87 u_int want_tty; 88 u_int want_subsys; 89 u_int want_x_fwd; 90 u_int want_agent_fwd; 91 Buffer cmd; 92 char *term; 93 struct termios tio; 94 char **env; 95 u_int rid; 96 }; 97 98 /* Context for stdio fwd open confirmation callback */ 99 struct mux_stdio_confirm_ctx { 100 u_int rid; 101 }; 102 103 /* Context for global channel callback */ 104 struct mux_channel_confirm_ctx { 105 u_int cid; /* channel id */ 106 u_int rid; /* request id */ 107 int fid; /* forward id */ 108 }; 109 110 /* fd to control socket */ 111 int muxserver_sock = -1; 112 113 /* client request id */ 114 u_int muxclient_request_id = 0; 115 116 /* Multiplexing control command */ 117 u_int muxclient_command = 0; 118 119 /* Set when signalled. */ 120 static volatile sig_atomic_t muxclient_terminate = 0; 121 122 /* PID of multiplex server */ 123 static u_int muxserver_pid = 0; 124 125 static Channel *mux_listener_channel = NULL; 126 127 struct mux_master_state { 128 int hello_rcvd; 129 }; 130 131 /* mux protocol messages */ 132 #define MUX_MSG_HELLO 0x00000001 133 #define MUX_C_NEW_SESSION 0x10000002 134 #define MUX_C_ALIVE_CHECK 0x10000004 135 #define MUX_C_TERMINATE 0x10000005 136 #define MUX_C_OPEN_FWD 0x10000006 137 #define MUX_C_CLOSE_FWD 0x10000007 138 #define MUX_C_NEW_STDIO_FWD 0x10000008 139 #define MUX_C_STOP_LISTENING 0x10000009 140 #define MUX_S_OK 0x80000001 141 #define MUX_S_PERMISSION_DENIED 0x80000002 142 #define MUX_S_FAILURE 0x80000003 143 #define MUX_S_EXIT_MESSAGE 0x80000004 144 #define MUX_S_ALIVE 0x80000005 145 #define MUX_S_SESSION_OPENED 0x80000006 146 #define MUX_S_REMOTE_PORT 0x80000007 147 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 148 149 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 150 #define MUX_FWD_LOCAL 1 151 #define MUX_FWD_REMOTE 2 152 #define MUX_FWD_DYNAMIC 3 153 154 static void mux_session_confirm(int, int, void *); 155 static void mux_stdio_confirm(int, int, void *); 156 157 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 158 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 159 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 160 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 161 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 162 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 163 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 164 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 165 166 static const struct { 167 u_int type; 168 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 169 } mux_master_handlers[] = { 170 { MUX_MSG_HELLO, process_mux_master_hello }, 171 { MUX_C_NEW_SESSION, process_mux_new_session }, 172 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 173 { MUX_C_TERMINATE, process_mux_terminate }, 174 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 175 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 176 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 177 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 178 { 0, NULL } 179 }; 180 181 /* Cleanup callback fired on closure of mux slave _session_ channel */ 182 /* ARGSUSED */ 183 static void 184 mux_master_session_cleanup_cb(int cid, void *unused) 185 { 186 Channel *cc, *c = channel_by_id(cid); 187 188 debug3("%s: entering for channel %d", __func__, cid); 189 if (c == NULL) 190 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 191 if (c->ctl_chan != -1) { 192 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 193 fatal("%s: channel %d missing control channel %d", 194 __func__, c->self, c->ctl_chan); 195 c->ctl_chan = -1; 196 cc->remote_id = -1; 197 chan_rcvd_oclose(cc); 198 } 199 channel_cancel_cleanup(c->self); 200 } 201 202 /* Cleanup callback fired on closure of mux slave _control_ channel */ 203 /* ARGSUSED */ 204 static void 205 mux_master_control_cleanup_cb(int cid, void *unused) 206 { 207 Channel *sc, *c = channel_by_id(cid); 208 209 debug3("%s: entering for channel %d", __func__, cid); 210 if (c == NULL) 211 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 212 if (c->remote_id != -1) { 213 if ((sc = channel_by_id(c->remote_id)) == NULL) 214 fatal("%s: channel %d missing session channel %d", 215 __func__, c->self, c->remote_id); 216 c->remote_id = -1; 217 sc->ctl_chan = -1; 218 if (sc->type != SSH_CHANNEL_OPEN && 219 sc->type != SSH_CHANNEL_OPENING) { 220 debug2("%s: channel %d: not open", __func__, sc->self); 221 chan_mark_dead(sc); 222 } else { 223 if (sc->istate == CHAN_INPUT_OPEN) 224 chan_read_failed(sc); 225 if (sc->ostate == CHAN_OUTPUT_OPEN) 226 chan_write_failed(sc); 227 } 228 } 229 channel_cancel_cleanup(c->self); 230 } 231 232 /* Check mux client environment variables before passing them to mux master. */ 233 static int 234 env_permitted(char *env) 235 { 236 int i, ret; 237 char name[1024], *cp; 238 239 if ((cp = strchr(env, '=')) == NULL || cp == env) 240 return 0; 241 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 242 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 243 error("env_permitted: name '%.100s...' too long", env); 244 return 0; 245 } 246 247 for (i = 0; i < options.num_send_env; i++) 248 if (match_pattern(name, options.send_env[i])) 249 return 1; 250 251 return 0; 252 } 253 254 /* Mux master protocol message handlers */ 255 256 static int 257 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 258 { 259 u_int ver; 260 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 261 262 if (state == NULL) 263 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 264 if (state->hello_rcvd) { 265 error("%s: HELLO received twice", __func__); 266 return -1; 267 } 268 if (buffer_get_int_ret(&ver, m) != 0) { 269 malf: 270 error("%s: malformed message", __func__); 271 return -1; 272 } 273 if (ver != SSHMUX_VER) { 274 error("Unsupported multiplexing protocol version %d " 275 "(expected %d)", ver, SSHMUX_VER); 276 return -1; 277 } 278 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 279 280 /* No extensions are presently defined */ 281 while (buffer_len(m) > 0) { 282 char *name = buffer_get_string_ret(m, NULL); 283 char *value = buffer_get_string_ret(m, NULL); 284 285 if (name == NULL || value == NULL) { 286 free(name); 287 free(value); 288 goto malf; 289 } 290 debug2("Unrecognised slave extension \"%s\"", name); 291 free(name); 292 free(value); 293 } 294 state->hello_rcvd = 1; 295 return 0; 296 } 297 298 static int 299 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 300 { 301 Channel *nc; 302 struct mux_session_confirm_ctx *cctx; 303 char *reserved, *cmd, *cp; 304 u_int i, j, len, env_len, escape_char, window, packetmax; 305 int new_fd[3]; 306 307 /* Reply for SSHMUX_COMMAND_OPEN */ 308 cctx = xcalloc(1, sizeof(*cctx)); 309 cctx->term = NULL; 310 cctx->rid = rid; 311 cmd = reserved = NULL; 312 cctx->env = NULL; 313 env_len = 0; 314 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 315 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 316 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 317 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 318 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 319 buffer_get_int_ret(&escape_char, m) != 0 || 320 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 321 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 322 malf: 323 free(cmd); 324 free(reserved); 325 for (j = 0; j < env_len; j++) 326 free(cctx->env[j]); 327 free(cctx->env); 328 free(cctx->term); 329 free(cctx); 330 error("%s: malformed message", __func__); 331 return -1; 332 } 333 free(reserved); 334 reserved = NULL; 335 336 while (buffer_len(m) > 0) { 337 #define MUX_MAX_ENV_VARS 4096 338 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 339 goto malf; 340 if (!env_permitted(cp)) { 341 free(cp); 342 continue; 343 } 344 cctx->env = xreallocarray(cctx->env, env_len + 2, 345 sizeof(*cctx->env)); 346 cctx->env[env_len++] = cp; 347 cctx->env[env_len] = NULL; 348 if (env_len > MUX_MAX_ENV_VARS) { 349 error(">%d environment variables received, ignoring " 350 "additional", MUX_MAX_ENV_VARS); 351 break; 352 } 353 } 354 355 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 356 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 357 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 358 cctx->want_subsys, cctx->term, cmd, env_len); 359 360 buffer_init(&cctx->cmd); 361 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 362 free(cmd); 363 cmd = NULL; 364 365 /* Gather fds from client */ 366 for(i = 0; i < 3; i++) { 367 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 368 error("%s: failed to receive fd %d from slave", 369 __func__, i); 370 for (j = 0; j < i; j++) 371 close(new_fd[j]); 372 for (j = 0; j < env_len; j++) 373 free(cctx->env[j]); 374 free(cctx->env); 375 free(cctx->term); 376 buffer_free(&cctx->cmd); 377 free(cctx); 378 379 /* prepare reply */ 380 buffer_put_int(r, MUX_S_FAILURE); 381 buffer_put_int(r, rid); 382 buffer_put_cstring(r, 383 "did not receive file descriptors"); 384 return -1; 385 } 386 } 387 388 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 389 new_fd[0], new_fd[1], new_fd[2]); 390 391 /* XXX support multiple child sessions in future */ 392 if (c->remote_id != -1) { 393 debug2("%s: session already open", __func__); 394 /* prepare reply */ 395 buffer_put_int(r, MUX_S_FAILURE); 396 buffer_put_int(r, rid); 397 buffer_put_cstring(r, "Multiple sessions not supported"); 398 cleanup: 399 close(new_fd[0]); 400 close(new_fd[1]); 401 close(new_fd[2]); 402 free(cctx->term); 403 if (env_len != 0) { 404 for (i = 0; i < env_len; i++) 405 free(cctx->env[i]); 406 free(cctx->env); 407 } 408 buffer_free(&cctx->cmd); 409 free(cctx); 410 return 0; 411 } 412 413 if (options.control_master == SSHCTL_MASTER_ASK || 414 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 415 if (!ask_permission("Allow shared connection to %s? ", host)) { 416 debug2("%s: session refused by user", __func__); 417 /* prepare reply */ 418 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 419 buffer_put_int(r, rid); 420 buffer_put_cstring(r, "Permission denied"); 421 goto cleanup; 422 } 423 } 424 425 /* Try to pick up ttymodes from client before it goes raw */ 426 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 427 error("%s: tcgetattr: %s", __func__, strerror(errno)); 428 429 /* enable nonblocking unless tty */ 430 if (!isatty(new_fd[0])) 431 set_nonblock(new_fd[0]); 432 if (!isatty(new_fd[1])) 433 set_nonblock(new_fd[1]); 434 if (!isatty(new_fd[2])) 435 set_nonblock(new_fd[2]); 436 437 window = CHAN_SES_WINDOW_DEFAULT; 438 packetmax = CHAN_SES_PACKET_DEFAULT; 439 if (cctx->want_tty) { 440 window >>= 1; 441 packetmax >>= 1; 442 } 443 444 nc = channel_new("session", SSH_CHANNEL_OPENING, 445 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 446 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 447 448 nc->ctl_chan = c->self; /* link session -> control channel */ 449 c->remote_id = nc->self; /* link control -> session channel */ 450 451 if (cctx->want_tty && escape_char != 0xffffffff) { 452 channel_register_filter(nc->self, 453 client_simple_escape_filter, NULL, 454 client_filter_cleanup, 455 client_new_escape_filter_ctx((int)escape_char)); 456 } 457 458 debug2("%s: channel_new: %d linked to control channel %d", 459 __func__, nc->self, nc->ctl_chan); 460 461 channel_send_open(nc->self); 462 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 463 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 464 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 465 466 /* reply is deferred, sent by mux_session_confirm */ 467 return 0; 468 } 469 470 static int 471 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 472 { 473 debug2("%s: channel %d: alive check", __func__, c->self); 474 475 /* prepare reply */ 476 buffer_put_int(r, MUX_S_ALIVE); 477 buffer_put_int(r, rid); 478 buffer_put_int(r, (u_int)getpid()); 479 480 return 0; 481 } 482 483 static int 484 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 485 { 486 debug2("%s: channel %d: terminate request", __func__, c->self); 487 488 if (options.control_master == SSHCTL_MASTER_ASK || 489 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 490 if (!ask_permission("Terminate shared connection to %s? ", 491 host)) { 492 debug2("%s: termination refused by user", __func__); 493 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 494 buffer_put_int(r, rid); 495 buffer_put_cstring(r, "Permission denied"); 496 return 0; 497 } 498 } 499 500 quit_pending = 1; 501 buffer_put_int(r, MUX_S_OK); 502 buffer_put_int(r, rid); 503 /* XXX exit happens too soon - message never makes it to client */ 504 return 0; 505 } 506 507 static char * 508 format_forward(u_int ftype, struct Forward *fwd) 509 { 510 char *ret; 511 512 switch (ftype) { 513 case MUX_FWD_LOCAL: 514 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 515 (fwd->listen_path != NULL) ? fwd->listen_path : 516 (fwd->listen_host == NULL) ? 517 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 518 fwd->listen_host, fwd->listen_port, 519 (fwd->connect_path != NULL) ? fwd->connect_path : 520 fwd->connect_host, fwd->connect_port); 521 break; 522 case MUX_FWD_DYNAMIC: 523 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 524 (fwd->listen_host == NULL) ? 525 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 526 fwd->listen_host, fwd->listen_port); 527 break; 528 case MUX_FWD_REMOTE: 529 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 530 (fwd->listen_path != NULL) ? fwd->listen_path : 531 (fwd->listen_host == NULL) ? 532 "LOCALHOST" : fwd->listen_host, 533 fwd->listen_port, 534 (fwd->connect_path != NULL) ? fwd->connect_path : 535 fwd->connect_host, fwd->connect_port); 536 break; 537 default: 538 fatal("%s: unknown forward type %u", __func__, ftype); 539 } 540 return ret; 541 } 542 543 static int 544 compare_host(const char *a, const char *b) 545 { 546 if (a == NULL && b == NULL) 547 return 1; 548 if (a == NULL || b == NULL) 549 return 0; 550 return strcmp(a, b) == 0; 551 } 552 553 static int 554 compare_forward(struct Forward *a, struct Forward *b) 555 { 556 if (!compare_host(a->listen_host, b->listen_host)) 557 return 0; 558 if (!compare_host(a->listen_path, b->listen_path)) 559 return 0; 560 if (a->listen_port != b->listen_port) 561 return 0; 562 if (!compare_host(a->connect_host, b->connect_host)) 563 return 0; 564 if (!compare_host(a->connect_path, b->connect_path)) 565 return 0; 566 if (a->connect_port != b->connect_port) 567 return 0; 568 569 return 1; 570 } 571 572 static void 573 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 574 { 575 struct mux_channel_confirm_ctx *fctx = ctxt; 576 char *failmsg = NULL; 577 struct Forward *rfwd; 578 Channel *c; 579 Buffer out; 580 581 if ((c = channel_by_id(fctx->cid)) == NULL) { 582 /* no channel for reply */ 583 error("%s: unknown channel", __func__); 584 return; 585 } 586 buffer_init(&out); 587 if (fctx->fid >= options.num_remote_forwards || 588 (options.remote_forwards[fctx->fid].connect_path == NULL && 589 options.remote_forwards[fctx->fid].connect_host == NULL)) { 590 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 591 goto fail; 592 } 593 rfwd = &options.remote_forwards[fctx->fid]; 594 debug("%s: %s for: listen %d, connect %s:%d", __func__, 595 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 596 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 597 rfwd->connect_host, rfwd->connect_port); 598 if (type == SSH2_MSG_REQUEST_SUCCESS) { 599 if (rfwd->listen_port == 0) { 600 rfwd->allocated_port = packet_get_int(); 601 debug("Allocated port %u for mux remote forward" 602 " to %s:%d", rfwd->allocated_port, 603 rfwd->connect_host, rfwd->connect_port); 604 buffer_put_int(&out, MUX_S_REMOTE_PORT); 605 buffer_put_int(&out, fctx->rid); 606 buffer_put_int(&out, rfwd->allocated_port); 607 channel_update_permitted_opens(rfwd->handle, 608 rfwd->allocated_port); 609 } else { 610 buffer_put_int(&out, MUX_S_OK); 611 buffer_put_int(&out, fctx->rid); 612 } 613 goto out; 614 } else { 615 if (rfwd->listen_port == 0) 616 channel_update_permitted_opens(rfwd->handle, -1); 617 if (rfwd->listen_path != NULL) 618 xasprintf(&failmsg, "remote port forwarding failed for " 619 "listen path %s", rfwd->listen_path); 620 else 621 xasprintf(&failmsg, "remote port forwarding failed for " 622 "listen port %d", rfwd->listen_port); 623 624 debug2("%s: clearing registered forwarding for listen %d, " 625 "connect %s:%d", __func__, rfwd->listen_port, 626 rfwd->connect_path ? rfwd->connect_path : 627 rfwd->connect_host, rfwd->connect_port); 628 629 free(rfwd->listen_host); 630 free(rfwd->listen_path); 631 free(rfwd->connect_host); 632 free(rfwd->connect_path); 633 memset(rfwd, 0, sizeof(*rfwd)); 634 } 635 fail: 636 error("%s: %s", __func__, failmsg); 637 buffer_put_int(&out, MUX_S_FAILURE); 638 buffer_put_int(&out, fctx->rid); 639 buffer_put_cstring(&out, failmsg); 640 free(failmsg); 641 out: 642 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 643 buffer_free(&out); 644 if (c->mux_pause <= 0) 645 fatal("%s: mux_pause %d", __func__, c->mux_pause); 646 c->mux_pause = 0; /* start processing messages again */ 647 } 648 649 static int 650 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 651 { 652 struct Forward fwd; 653 char *fwd_desc = NULL; 654 char *listen_addr, *connect_addr; 655 u_int ftype; 656 u_int lport, cport; 657 int i, ret = 0, freefwd = 1; 658 659 memset(&fwd, 0, sizeof(fwd)); 660 661 /* XXX - lport/cport check redundant */ 662 if (buffer_get_int_ret(&ftype, m) != 0 || 663 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 664 buffer_get_int_ret(&lport, m) != 0 || 665 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 666 buffer_get_int_ret(&cport, m) != 0 || 667 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 668 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 669 error("%s: malformed message", __func__); 670 ret = -1; 671 goto out; 672 } 673 if (*listen_addr == '\0') { 674 free(listen_addr); 675 listen_addr = NULL; 676 } 677 if (*connect_addr == '\0') { 678 free(connect_addr); 679 connect_addr = NULL; 680 } 681 682 memset(&fwd, 0, sizeof(fwd)); 683 fwd.listen_port = lport; 684 if (fwd.listen_port == PORT_STREAMLOCAL) 685 fwd.listen_path = listen_addr; 686 else 687 fwd.listen_host = listen_addr; 688 fwd.connect_port = cport; 689 if (fwd.connect_port == PORT_STREAMLOCAL) 690 fwd.connect_path = connect_addr; 691 else 692 fwd.connect_host = connect_addr; 693 694 debug2("%s: channel %d: request %s", __func__, c->self, 695 (fwd_desc = format_forward(ftype, &fwd))); 696 697 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 698 ftype != MUX_FWD_DYNAMIC) { 699 logit("%s: invalid forwarding type %u", __func__, ftype); 700 invalid: 701 free(listen_addr); 702 free(connect_addr); 703 buffer_put_int(r, MUX_S_FAILURE); 704 buffer_put_int(r, rid); 705 buffer_put_cstring(r, "Invalid forwarding request"); 706 return 0; 707 } 708 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 709 logit("%s: streamlocal and dynamic forwards " 710 "are mutually exclusive", __func__); 711 goto invalid; 712 } 713 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 714 logit("%s: invalid listen port %u", __func__, 715 fwd.listen_port); 716 goto invalid; 717 } 718 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 719 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 720 logit("%s: invalid connect port %u", __func__, 721 fwd.connect_port); 722 goto invalid; 723 } 724 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 725 logit("%s: missing connect host", __func__); 726 goto invalid; 727 } 728 729 /* Skip forwards that have already been requested */ 730 switch (ftype) { 731 case MUX_FWD_LOCAL: 732 case MUX_FWD_DYNAMIC: 733 for (i = 0; i < options.num_local_forwards; i++) { 734 if (compare_forward(&fwd, 735 options.local_forwards + i)) { 736 exists: 737 debug2("%s: found existing forwarding", 738 __func__); 739 buffer_put_int(r, MUX_S_OK); 740 buffer_put_int(r, rid); 741 goto out; 742 } 743 } 744 break; 745 case MUX_FWD_REMOTE: 746 for (i = 0; i < options.num_remote_forwards; i++) { 747 if (compare_forward(&fwd, 748 options.remote_forwards + i)) { 749 if (fwd.listen_port != 0) 750 goto exists; 751 debug2("%s: found allocated port", 752 __func__); 753 buffer_put_int(r, MUX_S_REMOTE_PORT); 754 buffer_put_int(r, rid); 755 buffer_put_int(r, 756 options.remote_forwards[i].allocated_port); 757 goto out; 758 } 759 } 760 break; 761 } 762 763 if (options.control_master == SSHCTL_MASTER_ASK || 764 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 765 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 766 debug2("%s: forwarding refused by user", __func__); 767 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 768 buffer_put_int(r, rid); 769 buffer_put_cstring(r, "Permission denied"); 770 goto out; 771 } 772 } 773 774 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 775 if (!channel_setup_local_fwd_listener(&fwd, 776 &options.fwd_opts)) { 777 fail: 778 logit("slave-requested %s failed", fwd_desc); 779 buffer_put_int(r, MUX_S_FAILURE); 780 buffer_put_int(r, rid); 781 buffer_put_cstring(r, "Port forwarding failed"); 782 goto out; 783 } 784 add_local_forward(&options, &fwd); 785 freefwd = 0; 786 } else { 787 struct mux_channel_confirm_ctx *fctx; 788 789 fwd.handle = channel_request_remote_forwarding(&fwd); 790 if (fwd.handle < 0) 791 goto fail; 792 add_remote_forward(&options, &fwd); 793 fctx = xcalloc(1, sizeof(*fctx)); 794 fctx->cid = c->self; 795 fctx->rid = rid; 796 fctx->fid = options.num_remote_forwards - 1; 797 client_register_global_confirm(mux_confirm_remote_forward, 798 fctx); 799 freefwd = 0; 800 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 801 /* delayed reply in mux_confirm_remote_forward */ 802 goto out; 803 } 804 buffer_put_int(r, MUX_S_OK); 805 buffer_put_int(r, rid); 806 out: 807 free(fwd_desc); 808 if (freefwd) { 809 free(fwd.listen_host); 810 free(fwd.listen_path); 811 free(fwd.connect_host); 812 free(fwd.connect_path); 813 } 814 return ret; 815 } 816 817 static int 818 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 819 { 820 struct Forward fwd, *found_fwd; 821 char *fwd_desc = NULL; 822 const char *error_reason = NULL; 823 char *listen_addr = NULL, *connect_addr = NULL; 824 u_int ftype; 825 int i, ret = 0; 826 u_int lport, cport; 827 828 memset(&fwd, 0, sizeof(fwd)); 829 830 if (buffer_get_int_ret(&ftype, m) != 0 || 831 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 832 buffer_get_int_ret(&lport, m) != 0 || 833 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 834 buffer_get_int_ret(&cport, m) != 0 || 835 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 836 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 837 error("%s: malformed message", __func__); 838 ret = -1; 839 goto out; 840 } 841 842 if (*listen_addr == '\0') { 843 free(listen_addr); 844 listen_addr = NULL; 845 } 846 if (*connect_addr == '\0') { 847 free(connect_addr); 848 connect_addr = NULL; 849 } 850 851 memset(&fwd, 0, sizeof(fwd)); 852 fwd.listen_port = lport; 853 if (fwd.listen_port == PORT_STREAMLOCAL) 854 fwd.listen_path = listen_addr; 855 else 856 fwd.listen_host = listen_addr; 857 fwd.connect_port = cport; 858 if (fwd.connect_port == PORT_STREAMLOCAL) 859 fwd.connect_path = connect_addr; 860 else 861 fwd.connect_host = connect_addr; 862 863 debug2("%s: channel %d: request cancel %s", __func__, c->self, 864 (fwd_desc = format_forward(ftype, &fwd))); 865 866 /* make sure this has been requested */ 867 found_fwd = NULL; 868 switch (ftype) { 869 case MUX_FWD_LOCAL: 870 case MUX_FWD_DYNAMIC: 871 for (i = 0; i < options.num_local_forwards; i++) { 872 if (compare_forward(&fwd, 873 options.local_forwards + i)) { 874 found_fwd = options.local_forwards + i; 875 break; 876 } 877 } 878 break; 879 case MUX_FWD_REMOTE: 880 for (i = 0; i < options.num_remote_forwards; i++) { 881 if (compare_forward(&fwd, 882 options.remote_forwards + i)) { 883 found_fwd = options.remote_forwards + i; 884 break; 885 } 886 } 887 break; 888 } 889 890 if (found_fwd == NULL) 891 error_reason = "port not forwarded"; 892 else if (ftype == MUX_FWD_REMOTE) { 893 /* 894 * This shouldn't fail unless we confused the host/port 895 * between options.remote_forwards and permitted_opens. 896 * However, for dynamic allocated listen ports we need 897 * to use the actual listen port. 898 */ 899 if (channel_request_rforward_cancel(found_fwd) == -1) 900 error_reason = "port not in permitted opens"; 901 } else { /* local and dynamic forwards */ 902 /* Ditto */ 903 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 904 &options.fwd_opts) == -1) 905 error_reason = "port not found"; 906 } 907 908 if (error_reason == NULL) { 909 buffer_put_int(r, MUX_S_OK); 910 buffer_put_int(r, rid); 911 912 free(found_fwd->listen_host); 913 free(found_fwd->listen_path); 914 free(found_fwd->connect_host); 915 free(found_fwd->connect_path); 916 found_fwd->listen_host = found_fwd->connect_host = NULL; 917 found_fwd->listen_path = found_fwd->connect_path = NULL; 918 found_fwd->listen_port = found_fwd->connect_port = 0; 919 } else { 920 buffer_put_int(r, MUX_S_FAILURE); 921 buffer_put_int(r, rid); 922 buffer_put_cstring(r, error_reason); 923 } 924 out: 925 free(fwd_desc); 926 free(listen_addr); 927 free(connect_addr); 928 929 return ret; 930 } 931 932 static int 933 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 934 { 935 Channel *nc; 936 char *reserved, *chost; 937 u_int cport, i, j; 938 int new_fd[2]; 939 struct mux_stdio_confirm_ctx *cctx; 940 941 chost = reserved = NULL; 942 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 943 (chost = buffer_get_string_ret(m, NULL)) == NULL || 944 buffer_get_int_ret(&cport, m) != 0) { 945 free(reserved); 946 free(chost); 947 error("%s: malformed message", __func__); 948 return -1; 949 } 950 free(reserved); 951 952 debug2("%s: channel %d: request stdio fwd to %s:%u", 953 __func__, c->self, chost, cport); 954 955 /* Gather fds from client */ 956 for(i = 0; i < 2; i++) { 957 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 958 error("%s: failed to receive fd %d from slave", 959 __func__, i); 960 for (j = 0; j < i; j++) 961 close(new_fd[j]); 962 free(chost); 963 964 /* prepare reply */ 965 buffer_put_int(r, MUX_S_FAILURE); 966 buffer_put_int(r, rid); 967 buffer_put_cstring(r, 968 "did not receive file descriptors"); 969 return -1; 970 } 971 } 972 973 debug3("%s: got fds stdin %d, stdout %d", __func__, 974 new_fd[0], new_fd[1]); 975 976 /* XXX support multiple child sessions in future */ 977 if (c->remote_id != -1) { 978 debug2("%s: session already open", __func__); 979 /* prepare reply */ 980 buffer_put_int(r, MUX_S_FAILURE); 981 buffer_put_int(r, rid); 982 buffer_put_cstring(r, "Multiple sessions not supported"); 983 cleanup: 984 close(new_fd[0]); 985 close(new_fd[1]); 986 free(chost); 987 return 0; 988 } 989 990 if (options.control_master == SSHCTL_MASTER_ASK || 991 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 992 if (!ask_permission("Allow forward to %s:%u? ", 993 chost, cport)) { 994 debug2("%s: stdio fwd refused by user", __func__); 995 /* prepare reply */ 996 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 997 buffer_put_int(r, rid); 998 buffer_put_cstring(r, "Permission denied"); 999 goto cleanup; 1000 } 1001 } 1002 1003 /* enable nonblocking unless tty */ 1004 if (!isatty(new_fd[0])) 1005 set_nonblock(new_fd[0]); 1006 if (!isatty(new_fd[1])) 1007 set_nonblock(new_fd[1]); 1008 1009 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1010 1011 nc->ctl_chan = c->self; /* link session -> control channel */ 1012 c->remote_id = nc->self; /* link control -> session channel */ 1013 1014 debug2("%s: channel_new: %d linked to control channel %d", 1015 __func__, nc->self, nc->ctl_chan); 1016 1017 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1018 1019 cctx = xcalloc(1, sizeof(*cctx)); 1020 cctx->rid = rid; 1021 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1022 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1023 1024 /* reply is deferred, sent by mux_session_confirm */ 1025 return 0; 1026 } 1027 1028 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1029 static void 1030 mux_stdio_confirm(int id, int success, void *arg) 1031 { 1032 struct mux_stdio_confirm_ctx *cctx = arg; 1033 Channel *c, *cc; 1034 Buffer reply; 1035 1036 if (cctx == NULL) 1037 fatal("%s: cctx == NULL", __func__); 1038 if ((c = channel_by_id(id)) == NULL) 1039 fatal("%s: no channel for id %d", __func__, id); 1040 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1041 fatal("%s: channel %d lacks control channel %d", __func__, 1042 id, c->ctl_chan); 1043 1044 if (!success) { 1045 debug3("%s: sending failure reply", __func__); 1046 /* prepare reply */ 1047 buffer_init(&reply); 1048 buffer_put_int(&reply, MUX_S_FAILURE); 1049 buffer_put_int(&reply, cctx->rid); 1050 buffer_put_cstring(&reply, "Session open refused by peer"); 1051 goto done; 1052 } 1053 1054 debug3("%s: sending success reply", __func__); 1055 /* prepare reply */ 1056 buffer_init(&reply); 1057 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1058 buffer_put_int(&reply, cctx->rid); 1059 buffer_put_int(&reply, c->self); 1060 1061 done: 1062 /* Send reply */ 1063 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1064 buffer_free(&reply); 1065 1066 if (cc->mux_pause <= 0) 1067 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1068 cc->mux_pause = 0; /* start processing messages again */ 1069 c->open_confirm_ctx = NULL; 1070 free(cctx); 1071 } 1072 1073 static int 1074 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1075 { 1076 debug("%s: channel %d: stop listening", __func__, c->self); 1077 1078 if (options.control_master == SSHCTL_MASTER_ASK || 1079 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1080 if (!ask_permission("Disable further multiplexing on shared " 1081 "connection to %s? ", host)) { 1082 debug2("%s: stop listen refused by user", __func__); 1083 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1084 buffer_put_int(r, rid); 1085 buffer_put_cstring(r, "Permission denied"); 1086 return 0; 1087 } 1088 } 1089 1090 if (mux_listener_channel != NULL) { 1091 channel_free(mux_listener_channel); 1092 client_stop_mux(); 1093 free(options.control_path); 1094 options.control_path = NULL; 1095 mux_listener_channel = NULL; 1096 muxserver_sock = -1; 1097 } 1098 1099 /* prepare reply */ 1100 buffer_put_int(r, MUX_S_OK); 1101 buffer_put_int(r, rid); 1102 1103 return 0; 1104 } 1105 1106 /* Channel callbacks fired on read/write from mux slave fd */ 1107 static int 1108 mux_master_read_cb(Channel *c) 1109 { 1110 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1111 Buffer in, out; 1112 const u_char *ptr; 1113 u_int type, rid, have, i; 1114 int ret = -1; 1115 1116 /* Setup ctx and */ 1117 if (c->mux_ctx == NULL) { 1118 state = xcalloc(1, sizeof(*state)); 1119 c->mux_ctx = state; 1120 channel_register_cleanup(c->self, 1121 mux_master_control_cleanup_cb, 0); 1122 1123 /* Send hello */ 1124 buffer_init(&out); 1125 buffer_put_int(&out, MUX_MSG_HELLO); 1126 buffer_put_int(&out, SSHMUX_VER); 1127 /* no extensions */ 1128 buffer_put_string(&c->output, buffer_ptr(&out), 1129 buffer_len(&out)); 1130 buffer_free(&out); 1131 debug3("%s: channel %d: hello sent", __func__, c->self); 1132 return 0; 1133 } 1134 1135 buffer_init(&in); 1136 buffer_init(&out); 1137 1138 /* Channel code ensures that we receive whole packets */ 1139 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1140 malf: 1141 error("%s: malformed message", __func__); 1142 goto out; 1143 } 1144 buffer_append(&in, ptr, have); 1145 1146 if (buffer_get_int_ret(&type, &in) != 0) 1147 goto malf; 1148 debug3("%s: channel %d packet type 0x%08x len %u", 1149 __func__, c->self, type, buffer_len(&in)); 1150 1151 if (type == MUX_MSG_HELLO) 1152 rid = 0; 1153 else { 1154 if (!state->hello_rcvd) { 1155 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1156 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1157 goto out; 1158 } 1159 if (buffer_get_int_ret(&rid, &in) != 0) 1160 goto malf; 1161 } 1162 1163 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1164 if (type == mux_master_handlers[i].type) { 1165 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1166 break; 1167 } 1168 } 1169 if (mux_master_handlers[i].handler == NULL) { 1170 error("%s: unsupported mux message 0x%08x", __func__, type); 1171 buffer_put_int(&out, MUX_S_FAILURE); 1172 buffer_put_int(&out, rid); 1173 buffer_put_cstring(&out, "unsupported request"); 1174 ret = 0; 1175 } 1176 /* Enqueue reply packet */ 1177 if (buffer_len(&out) != 0) { 1178 buffer_put_string(&c->output, buffer_ptr(&out), 1179 buffer_len(&out)); 1180 } 1181 out: 1182 buffer_free(&in); 1183 buffer_free(&out); 1184 return ret; 1185 } 1186 1187 void 1188 mux_exit_message(Channel *c, int exitval) 1189 { 1190 Buffer m; 1191 Channel *mux_chan; 1192 1193 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1194 exitval); 1195 1196 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1197 fatal("%s: channel %d missing mux channel %d", 1198 __func__, c->self, c->ctl_chan); 1199 1200 /* Append exit message packet to control socket output queue */ 1201 buffer_init(&m); 1202 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1203 buffer_put_int(&m, c->self); 1204 buffer_put_int(&m, exitval); 1205 1206 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1207 buffer_free(&m); 1208 } 1209 1210 void 1211 mux_tty_alloc_failed(Channel *c) 1212 { 1213 Buffer m; 1214 Channel *mux_chan; 1215 1216 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1217 1218 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1219 fatal("%s: channel %d missing mux channel %d", 1220 __func__, c->self, c->ctl_chan); 1221 1222 /* Append exit message packet to control socket output queue */ 1223 buffer_init(&m); 1224 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1225 buffer_put_int(&m, c->self); 1226 1227 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1228 buffer_free(&m); 1229 } 1230 1231 /* Prepare a mux master to listen on a Unix domain socket. */ 1232 void 1233 muxserver_listen(void) 1234 { 1235 mode_t old_umask; 1236 char *orig_control_path = options.control_path; 1237 char rbuf[16+1]; 1238 u_int i, r; 1239 int oerrno; 1240 1241 if (options.control_path == NULL || 1242 options.control_master == SSHCTL_MASTER_NO) 1243 return; 1244 1245 debug("setting up multiplex master socket"); 1246 1247 /* 1248 * Use a temporary path before listen so we can pseudo-atomically 1249 * establish the listening socket in its final location to avoid 1250 * other processes racing in between bind() and listen() and hitting 1251 * an unready socket. 1252 */ 1253 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1254 r = arc4random_uniform(26+26+10); 1255 rbuf[i] = (r < 26) ? 'a' + r : 1256 (r < 26*2) ? 'A' + r - 26 : 1257 '0' + r - 26 - 26; 1258 } 1259 rbuf[sizeof(rbuf) - 1] = '\0'; 1260 options.control_path = NULL; 1261 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1262 debug3("%s: temporary control path %s", __func__, options.control_path); 1263 1264 old_umask = umask(0177); 1265 muxserver_sock = unix_listener(options.control_path, 64, 0); 1266 oerrno = errno; 1267 umask(old_umask); 1268 if (muxserver_sock < 0) { 1269 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1270 error("ControlSocket %s already exists, " 1271 "disabling multiplexing", options.control_path); 1272 disable_mux_master: 1273 if (muxserver_sock != -1) { 1274 close(muxserver_sock); 1275 muxserver_sock = -1; 1276 } 1277 free(orig_control_path); 1278 free(options.control_path); 1279 options.control_path = NULL; 1280 options.control_master = SSHCTL_MASTER_NO; 1281 return; 1282 } else { 1283 /* unix_listener() logs the error */ 1284 cleanup_exit(255); 1285 } 1286 } 1287 1288 /* Now atomically "move" the mux socket into position */ 1289 if (link(options.control_path, orig_control_path) != 0) { 1290 if (errno != EEXIST) { 1291 fatal("%s: link mux listener %s => %s: %s", __func__, 1292 options.control_path, orig_control_path, 1293 strerror(errno)); 1294 } 1295 error("ControlSocket %s already exists, disabling multiplexing", 1296 orig_control_path); 1297 unlink(options.control_path); 1298 goto disable_mux_master; 1299 } 1300 unlink(options.control_path); 1301 free(options.control_path); 1302 options.control_path = orig_control_path; 1303 1304 set_nonblock(muxserver_sock); 1305 1306 mux_listener_channel = channel_new("mux listener", 1307 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1308 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1309 0, options.control_path, 1); 1310 mux_listener_channel->mux_rcb = mux_master_read_cb; 1311 debug3("%s: mux listener channel %d fd %d", __func__, 1312 mux_listener_channel->self, mux_listener_channel->sock); 1313 } 1314 1315 /* Callback on open confirmation in mux master for a mux client session. */ 1316 static void 1317 mux_session_confirm(int id, int success, void *arg) 1318 { 1319 struct mux_session_confirm_ctx *cctx = arg; 1320 const char *display; 1321 Channel *c, *cc; 1322 int i; 1323 Buffer reply; 1324 1325 if (cctx == NULL) 1326 fatal("%s: cctx == NULL", __func__); 1327 if ((c = channel_by_id(id)) == NULL) 1328 fatal("%s: no channel for id %d", __func__, id); 1329 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1330 fatal("%s: channel %d lacks control channel %d", __func__, 1331 id, c->ctl_chan); 1332 1333 if (!success) { 1334 debug3("%s: sending failure reply", __func__); 1335 /* prepare reply */ 1336 buffer_init(&reply); 1337 buffer_put_int(&reply, MUX_S_FAILURE); 1338 buffer_put_int(&reply, cctx->rid); 1339 buffer_put_cstring(&reply, "Session open refused by peer"); 1340 goto done; 1341 } 1342 1343 display = getenv("DISPLAY"); 1344 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1345 char *proto, *data; 1346 1347 /* Get reasonable local authentication information. */ 1348 if (client_x11_get_proto(display, options.xauth_location, 1349 options.forward_x11_trusted, options.forward_x11_timeout, 1350 &proto, &data) == 0) { 1351 /* Request forwarding with authentication spoofing. */ 1352 debug("Requesting X11 forwarding with authentication " 1353 "spoofing."); 1354 x11_request_forwarding_with_spoofing(id, display, proto, 1355 data, 1); 1356 /* XXX exit_on_forward_failure */ 1357 client_expect_confirm(id, "X11 forwarding", 1358 CONFIRM_WARN); 1359 } 1360 } 1361 1362 if (cctx->want_agent_fwd && options.forward_agent) { 1363 debug("Requesting authentication agent forwarding."); 1364 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1365 packet_send(); 1366 } 1367 1368 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1369 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1370 1371 debug3("%s: sending success reply", __func__); 1372 /* prepare reply */ 1373 buffer_init(&reply); 1374 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1375 buffer_put_int(&reply, cctx->rid); 1376 buffer_put_int(&reply, c->self); 1377 1378 done: 1379 /* Send reply */ 1380 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1381 buffer_free(&reply); 1382 1383 if (cc->mux_pause <= 0) 1384 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1385 cc->mux_pause = 0; /* start processing messages again */ 1386 c->open_confirm_ctx = NULL; 1387 buffer_free(&cctx->cmd); 1388 free(cctx->term); 1389 if (cctx->env != NULL) { 1390 for (i = 0; cctx->env[i] != NULL; i++) 1391 free(cctx->env[i]); 1392 free(cctx->env); 1393 } 1394 free(cctx); 1395 } 1396 1397 /* ** Multiplexing client support */ 1398 1399 /* Exit signal handler */ 1400 static void 1401 control_client_sighandler(int signo) 1402 { 1403 muxclient_terminate = signo; 1404 } 1405 1406 /* 1407 * Relay signal handler - used to pass some signals from mux client to 1408 * mux master. 1409 */ 1410 static void 1411 control_client_sigrelay(int signo) 1412 { 1413 int save_errno = errno; 1414 1415 if (muxserver_pid > 1) 1416 kill(muxserver_pid, signo); 1417 1418 errno = save_errno; 1419 } 1420 1421 static int 1422 mux_client_read(int fd, Buffer *b, u_int need) 1423 { 1424 u_int have; 1425 ssize_t len; 1426 u_char *p; 1427 struct pollfd pfd; 1428 1429 pfd.fd = fd; 1430 pfd.events = POLLIN; 1431 p = buffer_append_space(b, need); 1432 for (have = 0; have < need; ) { 1433 if (muxclient_terminate) { 1434 errno = EINTR; 1435 return -1; 1436 } 1437 len = read(fd, p + have, need - have); 1438 if (len < 0) { 1439 switch (errno) { 1440 case EAGAIN: 1441 (void)poll(&pfd, 1, -1); 1442 /* FALLTHROUGH */ 1443 case EINTR: 1444 continue; 1445 default: 1446 return -1; 1447 } 1448 } 1449 if (len == 0) { 1450 errno = EPIPE; 1451 return -1; 1452 } 1453 have += (u_int)len; 1454 } 1455 return 0; 1456 } 1457 1458 static int 1459 mux_client_write_packet(int fd, Buffer *m) 1460 { 1461 Buffer queue; 1462 u_int have, need; 1463 int oerrno, len; 1464 u_char *ptr; 1465 struct pollfd pfd; 1466 1467 pfd.fd = fd; 1468 pfd.events = POLLOUT; 1469 buffer_init(&queue); 1470 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1471 1472 need = buffer_len(&queue); 1473 ptr = buffer_ptr(&queue); 1474 1475 for (have = 0; have < need; ) { 1476 if (muxclient_terminate) { 1477 buffer_free(&queue); 1478 errno = EINTR; 1479 return -1; 1480 } 1481 len = write(fd, ptr + have, need - have); 1482 if (len < 0) { 1483 switch (errno) { 1484 case EAGAIN: 1485 (void)poll(&pfd, 1, -1); 1486 /* FALLTHROUGH */ 1487 case EINTR: 1488 continue; 1489 default: 1490 oerrno = errno; 1491 buffer_free(&queue); 1492 errno = oerrno; 1493 return -1; 1494 } 1495 } 1496 if (len == 0) { 1497 buffer_free(&queue); 1498 errno = EPIPE; 1499 return -1; 1500 } 1501 have += (u_int)len; 1502 } 1503 buffer_free(&queue); 1504 return 0; 1505 } 1506 1507 static int 1508 mux_client_read_packet(int fd, Buffer *m) 1509 { 1510 Buffer queue; 1511 u_int need, have; 1512 const u_char *ptr; 1513 int oerrno; 1514 1515 buffer_init(&queue); 1516 if (mux_client_read(fd, &queue, 4) != 0) { 1517 if ((oerrno = errno) == EPIPE) 1518 debug3("%s: read header failed: %s", __func__, 1519 strerror(errno)); 1520 buffer_free(&queue); 1521 errno = oerrno; 1522 return -1; 1523 } 1524 need = get_u32(buffer_ptr(&queue)); 1525 if (mux_client_read(fd, &queue, need) != 0) { 1526 oerrno = errno; 1527 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1528 buffer_free(&queue); 1529 errno = oerrno; 1530 return -1; 1531 } 1532 ptr = buffer_get_string_ptr(&queue, &have); 1533 buffer_append(m, ptr, have); 1534 buffer_free(&queue); 1535 return 0; 1536 } 1537 1538 static int 1539 mux_client_hello_exchange(int fd) 1540 { 1541 Buffer m; 1542 u_int type, ver; 1543 1544 buffer_init(&m); 1545 buffer_put_int(&m, MUX_MSG_HELLO); 1546 buffer_put_int(&m, SSHMUX_VER); 1547 /* no extensions */ 1548 1549 if (mux_client_write_packet(fd, &m) != 0) 1550 fatal("%s: write packet: %s", __func__, strerror(errno)); 1551 1552 buffer_clear(&m); 1553 1554 /* Read their HELLO */ 1555 if (mux_client_read_packet(fd, &m) != 0) { 1556 buffer_free(&m); 1557 return -1; 1558 } 1559 1560 type = buffer_get_int(&m); 1561 if (type != MUX_MSG_HELLO) 1562 fatal("%s: expected HELLO (%u) received %u", 1563 __func__, MUX_MSG_HELLO, type); 1564 ver = buffer_get_int(&m); 1565 if (ver != SSHMUX_VER) 1566 fatal("Unsupported multiplexing protocol version %d " 1567 "(expected %d)", ver, SSHMUX_VER); 1568 debug2("%s: master version %u", __func__, ver); 1569 /* No extensions are presently defined */ 1570 while (buffer_len(&m) > 0) { 1571 char *name = buffer_get_string(&m, NULL); 1572 char *value = buffer_get_string(&m, NULL); 1573 1574 debug2("Unrecognised master extension \"%s\"", name); 1575 free(name); 1576 free(value); 1577 } 1578 buffer_free(&m); 1579 return 0; 1580 } 1581 1582 static u_int 1583 mux_client_request_alive(int fd) 1584 { 1585 Buffer m; 1586 char *e; 1587 u_int pid, type, rid; 1588 1589 debug3("%s: entering", __func__); 1590 1591 buffer_init(&m); 1592 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1593 buffer_put_int(&m, muxclient_request_id); 1594 1595 if (mux_client_write_packet(fd, &m) != 0) 1596 fatal("%s: write packet: %s", __func__, strerror(errno)); 1597 1598 buffer_clear(&m); 1599 1600 /* Read their reply */ 1601 if (mux_client_read_packet(fd, &m) != 0) { 1602 buffer_free(&m); 1603 return 0; 1604 } 1605 1606 type = buffer_get_int(&m); 1607 if (type != MUX_S_ALIVE) { 1608 e = buffer_get_string(&m, NULL); 1609 fatal("%s: master returned error: %s", __func__, e); 1610 } 1611 1612 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1613 fatal("%s: out of sequence reply: my id %u theirs %u", 1614 __func__, muxclient_request_id, rid); 1615 pid = buffer_get_int(&m); 1616 buffer_free(&m); 1617 1618 debug3("%s: done pid = %u", __func__, pid); 1619 1620 muxclient_request_id++; 1621 1622 return pid; 1623 } 1624 1625 static void 1626 mux_client_request_terminate(int fd) 1627 { 1628 Buffer m; 1629 char *e; 1630 u_int type, rid; 1631 1632 debug3("%s: entering", __func__); 1633 1634 buffer_init(&m); 1635 buffer_put_int(&m, MUX_C_TERMINATE); 1636 buffer_put_int(&m, muxclient_request_id); 1637 1638 if (mux_client_write_packet(fd, &m) != 0) 1639 fatal("%s: write packet: %s", __func__, strerror(errno)); 1640 1641 buffer_clear(&m); 1642 1643 /* Read their reply */ 1644 if (mux_client_read_packet(fd, &m) != 0) { 1645 /* Remote end exited already */ 1646 if (errno == EPIPE) { 1647 buffer_free(&m); 1648 return; 1649 } 1650 fatal("%s: read from master failed: %s", 1651 __func__, strerror(errno)); 1652 } 1653 1654 type = buffer_get_int(&m); 1655 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1656 fatal("%s: out of sequence reply: my id %u theirs %u", 1657 __func__, muxclient_request_id, rid); 1658 switch (type) { 1659 case MUX_S_OK: 1660 break; 1661 case MUX_S_PERMISSION_DENIED: 1662 e = buffer_get_string(&m, NULL); 1663 fatal("Master refused termination request: %s", e); 1664 case MUX_S_FAILURE: 1665 e = buffer_get_string(&m, NULL); 1666 fatal("%s: termination request failed: %s", __func__, e); 1667 default: 1668 fatal("%s: unexpected response from master 0x%08x", 1669 __func__, type); 1670 } 1671 buffer_free(&m); 1672 muxclient_request_id++; 1673 } 1674 1675 static int 1676 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1677 { 1678 Buffer m; 1679 char *e, *fwd_desc; 1680 u_int type, rid; 1681 1682 fwd_desc = format_forward(ftype, fwd); 1683 debug("Requesting %s %s", 1684 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1685 free(fwd_desc); 1686 1687 buffer_init(&m); 1688 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1689 buffer_put_int(&m, muxclient_request_id); 1690 buffer_put_int(&m, ftype); 1691 if (fwd->listen_path != NULL) { 1692 buffer_put_cstring(&m, fwd->listen_path); 1693 } else { 1694 buffer_put_cstring(&m, 1695 fwd->listen_host == NULL ? "" : 1696 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1697 } 1698 buffer_put_int(&m, fwd->listen_port); 1699 if (fwd->connect_path != NULL) { 1700 buffer_put_cstring(&m, fwd->connect_path); 1701 } else { 1702 buffer_put_cstring(&m, 1703 fwd->connect_host == NULL ? "" : fwd->connect_host); 1704 } 1705 buffer_put_int(&m, fwd->connect_port); 1706 1707 if (mux_client_write_packet(fd, &m) != 0) 1708 fatal("%s: write packet: %s", __func__, strerror(errno)); 1709 1710 buffer_clear(&m); 1711 1712 /* Read their reply */ 1713 if (mux_client_read_packet(fd, &m) != 0) { 1714 buffer_free(&m); 1715 return -1; 1716 } 1717 1718 type = buffer_get_int(&m); 1719 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1720 fatal("%s: out of sequence reply: my id %u theirs %u", 1721 __func__, muxclient_request_id, rid); 1722 switch (type) { 1723 case MUX_S_OK: 1724 break; 1725 case MUX_S_REMOTE_PORT: 1726 if (cancel_flag) 1727 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1728 fwd->allocated_port = buffer_get_int(&m); 1729 verbose("Allocated port %u for remote forward to %s:%d", 1730 fwd->allocated_port, 1731 fwd->connect_host ? fwd->connect_host : "", 1732 fwd->connect_port); 1733 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1734 fprintf(stdout, "%i\n", fwd->allocated_port); 1735 break; 1736 case MUX_S_PERMISSION_DENIED: 1737 e = buffer_get_string(&m, NULL); 1738 buffer_free(&m); 1739 error("Master refused forwarding request: %s", e); 1740 return -1; 1741 case MUX_S_FAILURE: 1742 e = buffer_get_string(&m, NULL); 1743 buffer_free(&m); 1744 error("%s: forwarding request failed: %s", __func__, e); 1745 return -1; 1746 default: 1747 fatal("%s: unexpected response from master 0x%08x", 1748 __func__, type); 1749 } 1750 buffer_free(&m); 1751 1752 muxclient_request_id++; 1753 return 0; 1754 } 1755 1756 static int 1757 mux_client_forwards(int fd, int cancel_flag) 1758 { 1759 int i, ret = 0; 1760 1761 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1762 cancel_flag ? "cancel" : "request", 1763 options.num_local_forwards, options.num_remote_forwards); 1764 1765 /* XXX ExitOnForwardingFailure */ 1766 for (i = 0; i < options.num_local_forwards; i++) { 1767 if (mux_client_forward(fd, cancel_flag, 1768 options.local_forwards[i].connect_port == 0 ? 1769 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1770 options.local_forwards + i) != 0) 1771 ret = -1; 1772 } 1773 for (i = 0; i < options.num_remote_forwards; i++) { 1774 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1775 options.remote_forwards + i) != 0) 1776 ret = -1; 1777 } 1778 return ret; 1779 } 1780 1781 static int 1782 mux_client_request_session(int fd) 1783 { 1784 Buffer m; 1785 char *e, *term; 1786 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1787 extern char **environ; 1788 int devnull, rawmode; 1789 1790 debug3("%s: entering", __func__); 1791 1792 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1793 error("%s: master alive request failed", __func__); 1794 return -1; 1795 } 1796 1797 signal(SIGPIPE, SIG_IGN); 1798 1799 if (stdin_null_flag) { 1800 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1801 fatal("open(/dev/null): %s", strerror(errno)); 1802 if (dup2(devnull, STDIN_FILENO) == -1) 1803 fatal("dup2: %s", strerror(errno)); 1804 if (devnull > STDERR_FILENO) 1805 close(devnull); 1806 } 1807 1808 term = getenv("TERM"); 1809 1810 buffer_init(&m); 1811 buffer_put_int(&m, MUX_C_NEW_SESSION); 1812 buffer_put_int(&m, muxclient_request_id); 1813 buffer_put_cstring(&m, ""); /* reserved */ 1814 buffer_put_int(&m, tty_flag); 1815 buffer_put_int(&m, options.forward_x11); 1816 buffer_put_int(&m, options.forward_agent); 1817 buffer_put_int(&m, subsystem_flag); 1818 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1819 0xffffffff : (u_int)options.escape_char); 1820 buffer_put_cstring(&m, term == NULL ? "" : term); 1821 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1822 1823 if (options.num_send_env > 0 && environ != NULL) { 1824 /* Pass environment */ 1825 for (i = 0; environ[i] != NULL; i++) { 1826 if (env_permitted(environ[i])) { 1827 buffer_put_cstring(&m, environ[i]); 1828 } 1829 } 1830 } 1831 1832 if (mux_client_write_packet(fd, &m) != 0) 1833 fatal("%s: write packet: %s", __func__, strerror(errno)); 1834 1835 /* Send the stdio file descriptors */ 1836 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1837 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1838 mm_send_fd(fd, STDERR_FILENO) == -1) 1839 fatal("%s: send fds failed", __func__); 1840 1841 debug3("%s: session request sent", __func__); 1842 1843 /* Read their reply */ 1844 buffer_clear(&m); 1845 if (mux_client_read_packet(fd, &m) != 0) { 1846 error("%s: read from master failed: %s", 1847 __func__, strerror(errno)); 1848 buffer_free(&m); 1849 return -1; 1850 } 1851 1852 type = buffer_get_int(&m); 1853 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1854 fatal("%s: out of sequence reply: my id %u theirs %u", 1855 __func__, muxclient_request_id, rid); 1856 switch (type) { 1857 case MUX_S_SESSION_OPENED: 1858 sid = buffer_get_int(&m); 1859 debug("%s: master session id: %u", __func__, sid); 1860 break; 1861 case MUX_S_PERMISSION_DENIED: 1862 e = buffer_get_string(&m, NULL); 1863 buffer_free(&m); 1864 error("Master refused session request: %s", e); 1865 return -1; 1866 case MUX_S_FAILURE: 1867 e = buffer_get_string(&m, NULL); 1868 buffer_free(&m); 1869 error("%s: session request failed: %s", __func__, e); 1870 return -1; 1871 default: 1872 buffer_free(&m); 1873 error("%s: unexpected response from master 0x%08x", 1874 __func__, type); 1875 return -1; 1876 } 1877 muxclient_request_id++; 1878 1879 #ifdef __OpenBSD__ 1880 if (pledge("stdio proc tty", NULL) == -1) 1881 fatal("%s pledge(): %s", __func__, strerror(errno)); 1882 #endif 1883 1884 signal(SIGHUP, control_client_sighandler); 1885 signal(SIGINT, control_client_sighandler); 1886 signal(SIGTERM, control_client_sighandler); 1887 signal(SIGWINCH, control_client_sigrelay); 1888 1889 rawmode = tty_flag; 1890 if (tty_flag) 1891 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1892 1893 /* 1894 * Stick around until the controlee closes the client_fd. 1895 * Before it does, it is expected to write an exit message. 1896 * This process must read the value and wait for the closure of 1897 * the client_fd; if this one closes early, the multiplex master will 1898 * terminate early too (possibly losing data). 1899 */ 1900 for (exitval = 255, exitval_seen = 0;;) { 1901 buffer_clear(&m); 1902 if (mux_client_read_packet(fd, &m) != 0) 1903 break; 1904 type = buffer_get_int(&m); 1905 switch (type) { 1906 case MUX_S_TTY_ALLOC_FAIL: 1907 if ((esid = buffer_get_int(&m)) != sid) 1908 fatal("%s: tty alloc fail on unknown session: " 1909 "my id %u theirs %u", 1910 __func__, sid, esid); 1911 leave_raw_mode(options.request_tty == 1912 REQUEST_TTY_FORCE); 1913 rawmode = 0; 1914 continue; 1915 case MUX_S_EXIT_MESSAGE: 1916 if ((esid = buffer_get_int(&m)) != sid) 1917 fatal("%s: exit on unknown session: " 1918 "my id %u theirs %u", 1919 __func__, sid, esid); 1920 if (exitval_seen) 1921 fatal("%s: exitval sent twice", __func__); 1922 exitval = buffer_get_int(&m); 1923 exitval_seen = 1; 1924 continue; 1925 default: 1926 e = buffer_get_string(&m, NULL); 1927 fatal("%s: master returned error: %s", __func__, e); 1928 } 1929 } 1930 1931 close(fd); 1932 if (rawmode) 1933 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1934 1935 if (muxclient_terminate) { 1936 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1937 exitval = 255; 1938 } else if (!exitval_seen) { 1939 debug2("Control master terminated unexpectedly"); 1940 exitval = 255; 1941 } else 1942 debug2("Received exit status from master %d", exitval); 1943 1944 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1945 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1946 1947 exit(exitval); 1948 } 1949 1950 static int 1951 mux_client_request_stdio_fwd(int fd) 1952 { 1953 Buffer m; 1954 char *e; 1955 u_int type, rid, sid; 1956 int devnull; 1957 1958 debug3("%s: entering", __func__); 1959 1960 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1961 error("%s: master alive request failed", __func__); 1962 return -1; 1963 } 1964 1965 signal(SIGPIPE, SIG_IGN); 1966 1967 if (stdin_null_flag) { 1968 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1969 fatal("open(/dev/null): %s", strerror(errno)); 1970 if (dup2(devnull, STDIN_FILENO) == -1) 1971 fatal("dup2: %s", strerror(errno)); 1972 if (devnull > STDERR_FILENO) 1973 close(devnull); 1974 } 1975 1976 buffer_init(&m); 1977 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1978 buffer_put_int(&m, muxclient_request_id); 1979 buffer_put_cstring(&m, ""); /* reserved */ 1980 buffer_put_cstring(&m, stdio_forward_host); 1981 buffer_put_int(&m, stdio_forward_port); 1982 1983 if (mux_client_write_packet(fd, &m) != 0) 1984 fatal("%s: write packet: %s", __func__, strerror(errno)); 1985 1986 /* Send the stdio file descriptors */ 1987 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1988 mm_send_fd(fd, STDOUT_FILENO) == -1) 1989 fatal("%s: send fds failed", __func__); 1990 1991 #ifdef __OpenBSD__ 1992 if (pledge("stdio proc tty", NULL) == -1) 1993 fatal("%s pledge(): %s", __func__, strerror(errno)); 1994 #endif 1995 1996 debug3("%s: stdio forward request sent", __func__); 1997 1998 /* Read their reply */ 1999 buffer_clear(&m); 2000 2001 if (mux_client_read_packet(fd, &m) != 0) { 2002 error("%s: read from master failed: %s", 2003 __func__, strerror(errno)); 2004 buffer_free(&m); 2005 return -1; 2006 } 2007 2008 type = buffer_get_int(&m); 2009 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2010 fatal("%s: out of sequence reply: my id %u theirs %u", 2011 __func__, muxclient_request_id, rid); 2012 switch (type) { 2013 case MUX_S_SESSION_OPENED: 2014 sid = buffer_get_int(&m); 2015 debug("%s: master session id: %u", __func__, sid); 2016 break; 2017 case MUX_S_PERMISSION_DENIED: 2018 e = buffer_get_string(&m, NULL); 2019 buffer_free(&m); 2020 fatal("Master refused stdio forwarding request: %s", e); 2021 case MUX_S_FAILURE: 2022 e = buffer_get_string(&m, NULL); 2023 buffer_free(&m); 2024 fatal("Stdio forwarding request failed: %s", e); 2025 default: 2026 buffer_free(&m); 2027 error("%s: unexpected response from master 0x%08x", 2028 __func__, type); 2029 return -1; 2030 } 2031 muxclient_request_id++; 2032 2033 signal(SIGHUP, control_client_sighandler); 2034 signal(SIGINT, control_client_sighandler); 2035 signal(SIGTERM, control_client_sighandler); 2036 signal(SIGWINCH, control_client_sigrelay); 2037 2038 /* 2039 * Stick around until the controlee closes the client_fd. 2040 */ 2041 buffer_clear(&m); 2042 if (mux_client_read_packet(fd, &m) != 0) { 2043 if (errno == EPIPE || 2044 (errno == EINTR && muxclient_terminate != 0)) 2045 return 0; 2046 fatal("%s: mux_client_read_packet: %s", 2047 __func__, strerror(errno)); 2048 } 2049 fatal("%s: master returned unexpected message %u", __func__, type); 2050 } 2051 2052 static void 2053 mux_client_request_stop_listening(int fd) 2054 { 2055 Buffer m; 2056 char *e; 2057 u_int type, rid; 2058 2059 debug3("%s: entering", __func__); 2060 2061 buffer_init(&m); 2062 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2063 buffer_put_int(&m, muxclient_request_id); 2064 2065 if (mux_client_write_packet(fd, &m) != 0) 2066 fatal("%s: write packet: %s", __func__, strerror(errno)); 2067 2068 buffer_clear(&m); 2069 2070 /* Read their reply */ 2071 if (mux_client_read_packet(fd, &m) != 0) 2072 fatal("%s: read from master failed: %s", 2073 __func__, strerror(errno)); 2074 2075 type = buffer_get_int(&m); 2076 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2077 fatal("%s: out of sequence reply: my id %u theirs %u", 2078 __func__, muxclient_request_id, rid); 2079 switch (type) { 2080 case MUX_S_OK: 2081 break; 2082 case MUX_S_PERMISSION_DENIED: 2083 e = buffer_get_string(&m, NULL); 2084 fatal("Master refused stop listening request: %s", e); 2085 case MUX_S_FAILURE: 2086 e = buffer_get_string(&m, NULL); 2087 fatal("%s: stop listening request failed: %s", __func__, e); 2088 default: 2089 fatal("%s: unexpected response from master 0x%08x", 2090 __func__, type); 2091 } 2092 buffer_free(&m); 2093 muxclient_request_id++; 2094 } 2095 2096 /* Multiplex client main loop. */ 2097 void 2098 muxclient(const char *path) 2099 { 2100 struct sockaddr_un addr; 2101 int sock; 2102 u_int pid; 2103 2104 if (muxclient_command == 0) { 2105 if (stdio_forward_host != NULL) 2106 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2107 else 2108 muxclient_command = SSHMUX_COMMAND_OPEN; 2109 } 2110 2111 switch (options.control_master) { 2112 case SSHCTL_MASTER_AUTO: 2113 case SSHCTL_MASTER_AUTO_ASK: 2114 debug("auto-mux: Trying existing master"); 2115 /* FALLTHROUGH */ 2116 case SSHCTL_MASTER_NO: 2117 break; 2118 default: 2119 return; 2120 } 2121 2122 memset(&addr, '\0', sizeof(addr)); 2123 addr.sun_family = AF_UNIX; 2124 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 2125 strlen(path) + 1; 2126 2127 if (strlcpy(addr.sun_path, path, 2128 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2129 fatal("ControlPath too long"); 2130 2131 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2132 fatal("%s socket(): %s", __func__, strerror(errno)); 2133 2134 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 2135 switch (muxclient_command) { 2136 case SSHMUX_COMMAND_OPEN: 2137 case SSHMUX_COMMAND_STDIO_FWD: 2138 break; 2139 default: 2140 fatal("Control socket connect(%.100s): %s", path, 2141 strerror(errno)); 2142 } 2143 if (errno == ECONNREFUSED && 2144 options.control_master != SSHCTL_MASTER_NO) { 2145 debug("Stale control socket %.100s, unlinking", path); 2146 unlink(path); 2147 } else if (errno == ENOENT) { 2148 debug("Control socket \"%.100s\" does not exist", path); 2149 } else { 2150 error("Control socket connect(%.100s): %s", path, 2151 strerror(errno)); 2152 } 2153 close(sock); 2154 return; 2155 } 2156 set_nonblock(sock); 2157 2158 if (mux_client_hello_exchange(sock) != 0) { 2159 error("%s: master hello exchange failed", __func__); 2160 close(sock); 2161 return; 2162 } 2163 2164 switch (muxclient_command) { 2165 case SSHMUX_COMMAND_ALIVE_CHECK: 2166 if ((pid = mux_client_request_alive(sock)) == 0) 2167 fatal("%s: master alive check failed", __func__); 2168 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2169 exit(0); 2170 case SSHMUX_COMMAND_TERMINATE: 2171 mux_client_request_terminate(sock); 2172 fprintf(stderr, "Exit request sent.\r\n"); 2173 exit(0); 2174 case SSHMUX_COMMAND_FORWARD: 2175 if (mux_client_forwards(sock, 0) != 0) 2176 fatal("%s: master forward request failed", __func__); 2177 exit(0); 2178 case SSHMUX_COMMAND_OPEN: 2179 if (mux_client_forwards(sock, 0) != 0) { 2180 error("%s: master forward request failed", __func__); 2181 return; 2182 } 2183 mux_client_request_session(sock); 2184 return; 2185 case SSHMUX_COMMAND_STDIO_FWD: 2186 mux_client_request_stdio_fwd(sock); 2187 exit(0); 2188 case SSHMUX_COMMAND_STOP: 2189 mux_client_request_stop_listening(sock); 2190 fprintf(stderr, "Stop listening request sent.\r\n"); 2191 exit(0); 2192 case SSHMUX_COMMAND_CANCEL_FWD: 2193 if (mux_client_forwards(sock, 1) != 0) 2194 error("%s: master cancel forward request failed", 2195 __func__); 2196 exit(0); 2197 default: 2198 fatal("unrecognised muxclient_command %d", muxclient_command); 2199 } 2200 } 2201