1 /* $NetBSD: mux.c,v 1.17 2016/12/25 00:07:47 christos Exp $ */ 2 /* $OpenBSD: mux.c,v 1.63 2016/10/19 23:21:56 dtucker 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 1.17 2016/12/25 00:07:47 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 #include "ssherr.h" 74 75 /* from ssh.c */ 76 extern int tty_flag; 77 extern Options options; 78 extern int stdin_null_flag; 79 extern char *host; 80 extern int subsystem_flag; 81 extern Buffer command; 82 extern volatile sig_atomic_t quit_pending; 83 84 /* Context for session open confirmation callback */ 85 struct mux_session_confirm_ctx { 86 u_int want_tty; 87 u_int want_subsys; 88 u_int want_x_fwd; 89 u_int want_agent_fwd; 90 Buffer cmd; 91 char *term; 92 struct termios tio; 93 char **env; 94 u_int rid; 95 }; 96 97 /* Context for stdio fwd open confirmation callback */ 98 struct mux_stdio_confirm_ctx { 99 u_int rid; 100 }; 101 102 /* Context for global channel callback */ 103 struct mux_channel_confirm_ctx { 104 u_int cid; /* channel id */ 105 u_int rid; /* request id */ 106 int fid; /* forward id */ 107 }; 108 109 /* fd to control socket */ 110 int muxserver_sock = -1; 111 112 /* client request id */ 113 u_int muxclient_request_id = 0; 114 115 /* Multiplexing control command */ 116 u_int muxclient_command = 0; 117 118 /* Set when signalled. */ 119 static volatile sig_atomic_t muxclient_terminate = 0; 120 121 /* PID of multiplex server */ 122 static u_int muxserver_pid = 0; 123 124 static Channel *mux_listener_channel = NULL; 125 126 struct mux_master_state { 127 int hello_rcvd; 128 }; 129 130 /* mux protocol messages */ 131 #define MUX_MSG_HELLO 0x00000001 132 #define MUX_C_NEW_SESSION 0x10000002 133 #define MUX_C_ALIVE_CHECK 0x10000004 134 #define MUX_C_TERMINATE 0x10000005 135 #define MUX_C_OPEN_FWD 0x10000006 136 #define MUX_C_CLOSE_FWD 0x10000007 137 #define MUX_C_NEW_STDIO_FWD 0x10000008 138 #define MUX_C_STOP_LISTENING 0x10000009 139 #define MUX_C_PROXY 0x1000000f 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 #define MUX_S_PROXY 0x8000000f 149 150 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 151 #define MUX_FWD_LOCAL 1 152 #define MUX_FWD_REMOTE 2 153 #define MUX_FWD_DYNAMIC 3 154 155 static void mux_session_confirm(int, int, void *); 156 static void mux_stdio_confirm(int, int, void *); 157 158 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 159 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 160 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 161 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 162 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 163 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 164 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 165 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 166 static int process_mux_proxy(u_int, Channel *, Buffer *, Buffer *); 167 168 static const struct { 169 u_int type; 170 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 171 } mux_master_handlers[] = { 172 { MUX_MSG_HELLO, process_mux_master_hello }, 173 { MUX_C_NEW_SESSION, process_mux_new_session }, 174 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 175 { MUX_C_TERMINATE, process_mux_terminate }, 176 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 177 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 178 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 179 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 180 { MUX_C_PROXY, process_mux_proxy }, 181 { 0, NULL } 182 }; 183 184 /* Cleanup callback fired on closure of mux slave _session_ channel */ 185 /* ARGSUSED */ 186 static void 187 mux_master_session_cleanup_cb(int cid, void *unused) 188 { 189 Channel *cc, *c = channel_by_id(cid); 190 191 debug3("%s: entering for channel %d", __func__, cid); 192 if (c == NULL) 193 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 194 if (c->ctl_chan != -1) { 195 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 196 fatal("%s: channel %d missing control channel %d", 197 __func__, c->self, c->ctl_chan); 198 c->ctl_chan = -1; 199 cc->remote_id = -1; 200 chan_rcvd_oclose(cc); 201 } 202 channel_cancel_cleanup(c->self); 203 } 204 205 /* Cleanup callback fired on closure of mux slave _control_ channel */ 206 /* ARGSUSED */ 207 static void 208 mux_master_control_cleanup_cb(int cid, void *unused) 209 { 210 Channel *sc, *c = channel_by_id(cid); 211 212 debug3("%s: entering for channel %d", __func__, cid); 213 if (c == NULL) 214 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 215 if (c->remote_id != -1) { 216 if ((sc = channel_by_id(c->remote_id)) == NULL) 217 fatal("%s: channel %d missing session channel %d", 218 __func__, c->self, c->remote_id); 219 c->remote_id = -1; 220 sc->ctl_chan = -1; 221 if (sc->type != SSH_CHANNEL_OPEN && 222 sc->type != SSH_CHANNEL_OPENING) { 223 debug2("%s: channel %d: not open", __func__, sc->self); 224 chan_mark_dead(sc); 225 } else { 226 if (sc->istate == CHAN_INPUT_OPEN) 227 chan_read_failed(sc); 228 if (sc->ostate == CHAN_OUTPUT_OPEN) 229 chan_write_failed(sc); 230 } 231 } 232 channel_cancel_cleanup(c->self); 233 } 234 235 /* Check mux client environment variables before passing them to mux master. */ 236 static int 237 env_permitted(char *env) 238 { 239 int i, ret; 240 char name[1024], *cp; 241 242 if ((cp = strchr(env, '=')) == NULL || cp == env) 243 return 0; 244 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 245 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 246 error("env_permitted: name '%.100s...' too long", env); 247 return 0; 248 } 249 250 for (i = 0; i < options.num_send_env; i++) 251 if (match_pattern(name, options.send_env[i])) 252 return 1; 253 254 return 0; 255 } 256 257 /* Mux master protocol message handlers */ 258 259 static int 260 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 261 { 262 u_int ver; 263 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 264 265 if (state == NULL) 266 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 267 if (state->hello_rcvd) { 268 error("%s: HELLO received twice", __func__); 269 return -1; 270 } 271 if (buffer_get_int_ret(&ver, m) != 0) { 272 malf: 273 error("%s: malformed message", __func__); 274 return -1; 275 } 276 if (ver != SSHMUX_VER) { 277 error("Unsupported multiplexing protocol version %d " 278 "(expected %d)", ver, SSHMUX_VER); 279 return -1; 280 } 281 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 282 283 /* No extensions are presently defined */ 284 while (buffer_len(m) > 0) { 285 char *name = buffer_get_string_ret(m, NULL); 286 char *value = buffer_get_string_ret(m, NULL); 287 288 if (name == NULL || value == NULL) { 289 free(name); 290 free(value); 291 goto malf; 292 } 293 debug2("Unrecognised slave extension \"%s\"", name); 294 free(name); 295 free(value); 296 } 297 state->hello_rcvd = 1; 298 return 0; 299 } 300 301 static int 302 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 303 { 304 Channel *nc; 305 struct mux_session_confirm_ctx *cctx; 306 char *reserved, *cmd, *cp; 307 u_int i, j, len, env_len, escape_char, window, packetmax; 308 int new_fd[3]; 309 310 /* Reply for SSHMUX_COMMAND_OPEN */ 311 cctx = xcalloc(1, sizeof(*cctx)); 312 cctx->term = NULL; 313 cctx->rid = rid; 314 cmd = reserved = NULL; 315 cctx->env = NULL; 316 env_len = 0; 317 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 318 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 319 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 320 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 321 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 322 buffer_get_int_ret(&escape_char, m) != 0 || 323 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 324 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 325 malf: 326 free(cmd); 327 free(reserved); 328 for (j = 0; j < env_len; j++) 329 free(cctx->env[j]); 330 free(cctx->env); 331 free(cctx->term); 332 free(cctx); 333 error("%s: malformed message", __func__); 334 return -1; 335 } 336 free(reserved); 337 reserved = NULL; 338 339 while (buffer_len(m) > 0) { 340 #define MUX_MAX_ENV_VARS 4096 341 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 342 goto malf; 343 if (!env_permitted(cp)) { 344 free(cp); 345 continue; 346 } 347 cctx->env = xreallocarray(cctx->env, env_len + 2, 348 sizeof(*cctx->env)); 349 cctx->env[env_len++] = cp; 350 cctx->env[env_len] = NULL; 351 if (env_len > MUX_MAX_ENV_VARS) { 352 error(">%d environment variables received, ignoring " 353 "additional", MUX_MAX_ENV_VARS); 354 break; 355 } 356 } 357 358 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 359 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 360 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 361 cctx->want_subsys, cctx->term, cmd, env_len); 362 363 buffer_init(&cctx->cmd); 364 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 365 free(cmd); 366 cmd = NULL; 367 368 /* Gather fds from client */ 369 for(i = 0; i < 3; i++) { 370 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 371 error("%s: failed to receive fd %d from slave", 372 __func__, i); 373 for (j = 0; j < i; j++) 374 close(new_fd[j]); 375 for (j = 0; j < env_len; j++) 376 free(cctx->env[j]); 377 free(cctx->env); 378 free(cctx->term); 379 buffer_free(&cctx->cmd); 380 free(cctx); 381 382 /* prepare reply */ 383 buffer_put_int(r, MUX_S_FAILURE); 384 buffer_put_int(r, rid); 385 buffer_put_cstring(r, 386 "did not receive file descriptors"); 387 return -1; 388 } 389 } 390 391 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 392 new_fd[0], new_fd[1], new_fd[2]); 393 394 /* XXX support multiple child sessions in future */ 395 if (c->remote_id != -1) { 396 debug2("%s: session already open", __func__); 397 /* prepare reply */ 398 buffer_put_int(r, MUX_S_FAILURE); 399 buffer_put_int(r, rid); 400 buffer_put_cstring(r, "Multiple sessions not supported"); 401 cleanup: 402 close(new_fd[0]); 403 close(new_fd[1]); 404 close(new_fd[2]); 405 free(cctx->term); 406 if (env_len != 0) { 407 for (i = 0; i < env_len; i++) 408 free(cctx->env[i]); 409 free(cctx->env); 410 } 411 buffer_free(&cctx->cmd); 412 free(cctx); 413 return 0; 414 } 415 416 if (options.control_master == SSHCTL_MASTER_ASK || 417 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 418 if (!ask_permission("Allow shared connection to %s? ", host)) { 419 debug2("%s: session refused by user", __func__); 420 /* prepare reply */ 421 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 422 buffer_put_int(r, rid); 423 buffer_put_cstring(r, "Permission denied"); 424 goto cleanup; 425 } 426 } 427 428 /* Try to pick up ttymodes from client before it goes raw */ 429 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 430 error("%s: tcgetattr: %s", __func__, strerror(errno)); 431 432 /* enable nonblocking unless tty */ 433 if (!isatty(new_fd[0])) 434 set_nonblock(new_fd[0]); 435 if (!isatty(new_fd[1])) 436 set_nonblock(new_fd[1]); 437 if (!isatty(new_fd[2])) 438 set_nonblock(new_fd[2]); 439 440 window = CHAN_SES_WINDOW_DEFAULT; 441 packetmax = CHAN_SES_PACKET_DEFAULT; 442 if (cctx->want_tty) { 443 window >>= 1; 444 packetmax >>= 1; 445 } 446 447 nc = channel_new("session", SSH_CHANNEL_OPENING, 448 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 449 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 450 451 nc->ctl_chan = c->self; /* link session -> control channel */ 452 c->remote_id = nc->self; /* link control -> session channel */ 453 454 if (cctx->want_tty && escape_char != 0xffffffff) { 455 channel_register_filter(nc->self, 456 client_simple_escape_filter, NULL, 457 client_filter_cleanup, 458 client_new_escape_filter_ctx((int)escape_char)); 459 } 460 461 debug2("%s: channel_new: %d linked to control channel %d", 462 __func__, nc->self, nc->ctl_chan); 463 464 channel_send_open(nc->self); 465 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 466 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 467 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 468 469 /* reply is deferred, sent by mux_session_confirm */ 470 return 0; 471 } 472 473 static int 474 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 475 { 476 debug2("%s: channel %d: alive check", __func__, c->self); 477 478 /* prepare reply */ 479 buffer_put_int(r, MUX_S_ALIVE); 480 buffer_put_int(r, rid); 481 buffer_put_int(r, (u_int)getpid()); 482 483 return 0; 484 } 485 486 static int 487 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 488 { 489 debug2("%s: channel %d: terminate request", __func__, c->self); 490 491 if (options.control_master == SSHCTL_MASTER_ASK || 492 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 493 if (!ask_permission("Terminate shared connection to %s? ", 494 host)) { 495 debug2("%s: termination refused by user", __func__); 496 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 497 buffer_put_int(r, rid); 498 buffer_put_cstring(r, "Permission denied"); 499 return 0; 500 } 501 } 502 503 quit_pending = 1; 504 buffer_put_int(r, MUX_S_OK); 505 buffer_put_int(r, rid); 506 /* XXX exit happens too soon - message never makes it to client */ 507 return 0; 508 } 509 510 static char * 511 format_forward(u_int ftype, struct Forward *fwd) 512 { 513 char *ret; 514 515 switch (ftype) { 516 case MUX_FWD_LOCAL: 517 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 518 (fwd->listen_path != NULL) ? fwd->listen_path : 519 (fwd->listen_host == NULL) ? 520 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 521 fwd->listen_host, fwd->listen_port, 522 (fwd->connect_path != NULL) ? fwd->connect_path : 523 fwd->connect_host, fwd->connect_port); 524 break; 525 case MUX_FWD_DYNAMIC: 526 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 527 (fwd->listen_host == NULL) ? 528 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 529 fwd->listen_host, fwd->listen_port); 530 break; 531 case MUX_FWD_REMOTE: 532 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 533 (fwd->listen_path != NULL) ? fwd->listen_path : 534 (fwd->listen_host == NULL) ? 535 "LOCALHOST" : fwd->listen_host, 536 fwd->listen_port, 537 (fwd->connect_path != NULL) ? fwd->connect_path : 538 fwd->connect_host, fwd->connect_port); 539 break; 540 default: 541 fatal("%s: unknown forward type %u", __func__, ftype); 542 } 543 return ret; 544 } 545 546 static int 547 compare_host(const char *a, const char *b) 548 { 549 if (a == NULL && b == NULL) 550 return 1; 551 if (a == NULL || b == NULL) 552 return 0; 553 return strcmp(a, b) == 0; 554 } 555 556 static int 557 compare_forward(struct Forward *a, struct Forward *b) 558 { 559 if (!compare_host(a->listen_host, b->listen_host)) 560 return 0; 561 if (!compare_host(a->listen_path, b->listen_path)) 562 return 0; 563 if (a->listen_port != b->listen_port) 564 return 0; 565 if (!compare_host(a->connect_host, b->connect_host)) 566 return 0; 567 if (!compare_host(a->connect_path, b->connect_path)) 568 return 0; 569 if (a->connect_port != b->connect_port) 570 return 0; 571 572 return 1; 573 } 574 575 static void 576 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 577 { 578 struct mux_channel_confirm_ctx *fctx = ctxt; 579 char *failmsg = NULL; 580 struct Forward *rfwd; 581 Channel *c; 582 Buffer out; 583 584 if ((c = channel_by_id(fctx->cid)) == NULL) { 585 /* no channel for reply */ 586 error("%s: unknown channel", __func__); 587 return; 588 } 589 buffer_init(&out); 590 if (fctx->fid >= options.num_remote_forwards || 591 (options.remote_forwards[fctx->fid].connect_path == NULL && 592 options.remote_forwards[fctx->fid].connect_host == NULL)) { 593 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 594 goto fail; 595 } 596 rfwd = &options.remote_forwards[fctx->fid]; 597 debug("%s: %s for: listen %d, connect %s:%d", __func__, 598 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 599 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 600 rfwd->connect_host, rfwd->connect_port); 601 if (type == SSH2_MSG_REQUEST_SUCCESS) { 602 if (rfwd->listen_port == 0) { 603 rfwd->allocated_port = packet_get_int(); 604 debug("Allocated port %u for mux remote forward" 605 " to %s:%d", rfwd->allocated_port, 606 rfwd->connect_host, rfwd->connect_port); 607 buffer_put_int(&out, MUX_S_REMOTE_PORT); 608 buffer_put_int(&out, fctx->rid); 609 buffer_put_int(&out, rfwd->allocated_port); 610 channel_update_permitted_opens(rfwd->handle, 611 rfwd->allocated_port); 612 } else { 613 buffer_put_int(&out, MUX_S_OK); 614 buffer_put_int(&out, fctx->rid); 615 } 616 goto out; 617 } else { 618 if (rfwd->listen_port == 0) 619 channel_update_permitted_opens(rfwd->handle, -1); 620 if (rfwd->listen_path != NULL) 621 xasprintf(&failmsg, "remote port forwarding failed for " 622 "listen path %s", rfwd->listen_path); 623 else 624 xasprintf(&failmsg, "remote port forwarding failed for " 625 "listen port %d", rfwd->listen_port); 626 627 debug2("%s: clearing registered forwarding for listen %d, " 628 "connect %s:%d", __func__, rfwd->listen_port, 629 rfwd->connect_path ? rfwd->connect_path : 630 rfwd->connect_host, rfwd->connect_port); 631 632 free(rfwd->listen_host); 633 free(rfwd->listen_path); 634 free(rfwd->connect_host); 635 free(rfwd->connect_path); 636 memset(rfwd, 0, sizeof(*rfwd)); 637 } 638 fail: 639 error("%s: %s", __func__, failmsg); 640 buffer_put_int(&out, MUX_S_FAILURE); 641 buffer_put_int(&out, fctx->rid); 642 buffer_put_cstring(&out, failmsg); 643 free(failmsg); 644 out: 645 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 646 buffer_free(&out); 647 if (c->mux_pause <= 0) 648 fatal("%s: mux_pause %d", __func__, c->mux_pause); 649 c->mux_pause = 0; /* start processing messages again */ 650 } 651 652 static int 653 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 654 { 655 struct Forward fwd; 656 char *fwd_desc = NULL; 657 char *listen_addr, *connect_addr; 658 u_int ftype; 659 u_int lport, cport; 660 int i, ret = 0, freefwd = 1; 661 662 memset(&fwd, 0, sizeof(fwd)); 663 664 /* XXX - lport/cport check redundant */ 665 if (buffer_get_int_ret(&ftype, m) != 0 || 666 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 667 buffer_get_int_ret(&lport, m) != 0 || 668 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 669 buffer_get_int_ret(&cport, m) != 0 || 670 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 671 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 672 error("%s: malformed message", __func__); 673 ret = -1; 674 goto out; 675 } 676 if (*listen_addr == '\0') { 677 free(listen_addr); 678 listen_addr = NULL; 679 } 680 if (*connect_addr == '\0') { 681 free(connect_addr); 682 connect_addr = NULL; 683 } 684 685 memset(&fwd, 0, sizeof(fwd)); 686 fwd.listen_port = lport; 687 if (fwd.listen_port == PORT_STREAMLOCAL) 688 fwd.listen_path = listen_addr; 689 else 690 fwd.listen_host = listen_addr; 691 fwd.connect_port = cport; 692 if (fwd.connect_port == PORT_STREAMLOCAL) 693 fwd.connect_path = connect_addr; 694 else 695 fwd.connect_host = connect_addr; 696 697 debug2("%s: channel %d: request %s", __func__, c->self, 698 (fwd_desc = format_forward(ftype, &fwd))); 699 700 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 701 ftype != MUX_FWD_DYNAMIC) { 702 logit("%s: invalid forwarding type %u", __func__, ftype); 703 invalid: 704 free(listen_addr); 705 free(connect_addr); 706 buffer_put_int(r, MUX_S_FAILURE); 707 buffer_put_int(r, rid); 708 buffer_put_cstring(r, "Invalid forwarding request"); 709 return 0; 710 } 711 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 712 logit("%s: streamlocal and dynamic forwards " 713 "are mutually exclusive", __func__); 714 goto invalid; 715 } 716 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 717 logit("%s: invalid listen port %u", __func__, 718 fwd.listen_port); 719 goto invalid; 720 } 721 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 722 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 723 logit("%s: invalid connect port %u", __func__, 724 fwd.connect_port); 725 goto invalid; 726 } 727 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 728 logit("%s: missing connect host", __func__); 729 goto invalid; 730 } 731 732 /* Skip forwards that have already been requested */ 733 switch (ftype) { 734 case MUX_FWD_LOCAL: 735 case MUX_FWD_DYNAMIC: 736 for (i = 0; i < options.num_local_forwards; i++) { 737 if (compare_forward(&fwd, 738 options.local_forwards + i)) { 739 exists: 740 debug2("%s: found existing forwarding", 741 __func__); 742 buffer_put_int(r, MUX_S_OK); 743 buffer_put_int(r, rid); 744 goto out; 745 } 746 } 747 break; 748 case MUX_FWD_REMOTE: 749 for (i = 0; i < options.num_remote_forwards; i++) { 750 if (compare_forward(&fwd, 751 options.remote_forwards + i)) { 752 if (fwd.listen_port != 0) 753 goto exists; 754 debug2("%s: found allocated port", 755 __func__); 756 buffer_put_int(r, MUX_S_REMOTE_PORT); 757 buffer_put_int(r, rid); 758 buffer_put_int(r, 759 options.remote_forwards[i].allocated_port); 760 goto out; 761 } 762 } 763 break; 764 } 765 766 if (options.control_master == SSHCTL_MASTER_ASK || 767 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 768 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 769 debug2("%s: forwarding refused by user", __func__); 770 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 771 buffer_put_int(r, rid); 772 buffer_put_cstring(r, "Permission denied"); 773 goto out; 774 } 775 } 776 777 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 778 if (!channel_setup_local_fwd_listener(&fwd, 779 &options.fwd_opts)) { 780 fail: 781 logit("slave-requested %s failed", fwd_desc); 782 buffer_put_int(r, MUX_S_FAILURE); 783 buffer_put_int(r, rid); 784 buffer_put_cstring(r, "Port forwarding failed"); 785 goto out; 786 } 787 add_local_forward(&options, &fwd); 788 freefwd = 0; 789 } else { 790 struct mux_channel_confirm_ctx *fctx; 791 792 fwd.handle = channel_request_remote_forwarding(&fwd); 793 if (fwd.handle < 0) 794 goto fail; 795 add_remote_forward(&options, &fwd); 796 fctx = xcalloc(1, sizeof(*fctx)); 797 fctx->cid = c->self; 798 fctx->rid = rid; 799 fctx->fid = options.num_remote_forwards - 1; 800 client_register_global_confirm(mux_confirm_remote_forward, 801 fctx); 802 freefwd = 0; 803 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 804 /* delayed reply in mux_confirm_remote_forward */ 805 goto out; 806 } 807 buffer_put_int(r, MUX_S_OK); 808 buffer_put_int(r, rid); 809 out: 810 free(fwd_desc); 811 if (freefwd) { 812 free(fwd.listen_host); 813 free(fwd.listen_path); 814 free(fwd.connect_host); 815 free(fwd.connect_path); 816 } 817 return ret; 818 } 819 820 static int 821 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 822 { 823 struct Forward fwd, *found_fwd; 824 char *fwd_desc = NULL; 825 const char *error_reason = NULL; 826 char *listen_addr = NULL, *connect_addr = NULL; 827 u_int ftype; 828 int i, ret = 0; 829 u_int lport, cport; 830 831 memset(&fwd, 0, sizeof(fwd)); 832 833 if (buffer_get_int_ret(&ftype, m) != 0 || 834 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 835 buffer_get_int_ret(&lport, m) != 0 || 836 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 837 buffer_get_int_ret(&cport, m) != 0 || 838 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 839 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 840 error("%s: malformed message", __func__); 841 ret = -1; 842 goto out; 843 } 844 845 if (*listen_addr == '\0') { 846 free(listen_addr); 847 listen_addr = NULL; 848 } 849 if (*connect_addr == '\0') { 850 free(connect_addr); 851 connect_addr = NULL; 852 } 853 854 memset(&fwd, 0, sizeof(fwd)); 855 fwd.listen_port = lport; 856 if (fwd.listen_port == PORT_STREAMLOCAL) 857 fwd.listen_path = listen_addr; 858 else 859 fwd.listen_host = listen_addr; 860 fwd.connect_port = cport; 861 if (fwd.connect_port == PORT_STREAMLOCAL) 862 fwd.connect_path = connect_addr; 863 else 864 fwd.connect_host = connect_addr; 865 866 debug2("%s: channel %d: request cancel %s", __func__, c->self, 867 (fwd_desc = format_forward(ftype, &fwd))); 868 869 /* make sure this has been requested */ 870 found_fwd = NULL; 871 switch (ftype) { 872 case MUX_FWD_LOCAL: 873 case MUX_FWD_DYNAMIC: 874 for (i = 0; i < options.num_local_forwards; i++) { 875 if (compare_forward(&fwd, 876 options.local_forwards + i)) { 877 found_fwd = options.local_forwards + i; 878 break; 879 } 880 } 881 break; 882 case MUX_FWD_REMOTE: 883 for (i = 0; i < options.num_remote_forwards; i++) { 884 if (compare_forward(&fwd, 885 options.remote_forwards + i)) { 886 found_fwd = options.remote_forwards + i; 887 break; 888 } 889 } 890 break; 891 } 892 893 if (found_fwd == NULL) 894 error_reason = "port not forwarded"; 895 else if (ftype == MUX_FWD_REMOTE) { 896 /* 897 * This shouldn't fail unless we confused the host/port 898 * between options.remote_forwards and permitted_opens. 899 * However, for dynamic allocated listen ports we need 900 * to use the actual listen port. 901 */ 902 if (channel_request_rforward_cancel(found_fwd) == -1) 903 error_reason = "port not in permitted opens"; 904 } else { /* local and dynamic forwards */ 905 /* Ditto */ 906 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 907 &options.fwd_opts) == -1) 908 error_reason = "port not found"; 909 } 910 911 if (error_reason == NULL) { 912 buffer_put_int(r, MUX_S_OK); 913 buffer_put_int(r, rid); 914 915 free(found_fwd->listen_host); 916 free(found_fwd->listen_path); 917 free(found_fwd->connect_host); 918 free(found_fwd->connect_path); 919 found_fwd->listen_host = found_fwd->connect_host = NULL; 920 found_fwd->listen_path = found_fwd->connect_path = NULL; 921 found_fwd->listen_port = found_fwd->connect_port = 0; 922 } else { 923 buffer_put_int(r, MUX_S_FAILURE); 924 buffer_put_int(r, rid); 925 buffer_put_cstring(r, error_reason); 926 } 927 out: 928 free(fwd_desc); 929 free(listen_addr); 930 free(connect_addr); 931 932 return ret; 933 } 934 935 static int 936 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 937 { 938 Channel *nc; 939 char *reserved, *chost; 940 u_int cport, i, j; 941 int new_fd[2]; 942 struct mux_stdio_confirm_ctx *cctx; 943 944 chost = reserved = NULL; 945 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 946 (chost = buffer_get_string_ret(m, NULL)) == NULL || 947 buffer_get_int_ret(&cport, m) != 0) { 948 free(reserved); 949 free(chost); 950 error("%s: malformed message", __func__); 951 return -1; 952 } 953 free(reserved); 954 955 debug2("%s: channel %d: request stdio fwd to %s:%u", 956 __func__, c->self, chost, cport); 957 958 /* Gather fds from client */ 959 for(i = 0; i < 2; i++) { 960 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 961 error("%s: failed to receive fd %d from slave", 962 __func__, i); 963 for (j = 0; j < i; j++) 964 close(new_fd[j]); 965 free(chost); 966 967 /* prepare reply */ 968 buffer_put_int(r, MUX_S_FAILURE); 969 buffer_put_int(r, rid); 970 buffer_put_cstring(r, 971 "did not receive file descriptors"); 972 return -1; 973 } 974 } 975 976 debug3("%s: got fds stdin %d, stdout %d", __func__, 977 new_fd[0], new_fd[1]); 978 979 /* XXX support multiple child sessions in future */ 980 if (c->remote_id != -1) { 981 debug2("%s: session already open", __func__); 982 /* prepare reply */ 983 buffer_put_int(r, MUX_S_FAILURE); 984 buffer_put_int(r, rid); 985 buffer_put_cstring(r, "Multiple sessions not supported"); 986 cleanup: 987 close(new_fd[0]); 988 close(new_fd[1]); 989 free(chost); 990 return 0; 991 } 992 993 if (options.control_master == SSHCTL_MASTER_ASK || 994 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 995 if (!ask_permission("Allow forward to %s:%u? ", 996 chost, cport)) { 997 debug2("%s: stdio fwd refused by user", __func__); 998 /* prepare reply */ 999 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1000 buffer_put_int(r, rid); 1001 buffer_put_cstring(r, "Permission denied"); 1002 goto cleanup; 1003 } 1004 } 1005 1006 /* enable nonblocking unless tty */ 1007 if (!isatty(new_fd[0])) 1008 set_nonblock(new_fd[0]); 1009 if (!isatty(new_fd[1])) 1010 set_nonblock(new_fd[1]); 1011 1012 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1013 1014 nc->ctl_chan = c->self; /* link session -> control channel */ 1015 c->remote_id = nc->self; /* link control -> session channel */ 1016 1017 debug2("%s: channel_new: %d linked to control channel %d", 1018 __func__, nc->self, nc->ctl_chan); 1019 1020 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1021 1022 cctx = xcalloc(1, sizeof(*cctx)); 1023 cctx->rid = rid; 1024 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1025 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1026 1027 /* reply is deferred, sent by mux_session_confirm */ 1028 return 0; 1029 } 1030 1031 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1032 static void 1033 mux_stdio_confirm(int id, int success, void *arg) 1034 { 1035 struct mux_stdio_confirm_ctx *cctx = arg; 1036 Channel *c, *cc; 1037 Buffer reply; 1038 1039 if (cctx == NULL) 1040 fatal("%s: cctx == NULL", __func__); 1041 if ((c = channel_by_id(id)) == NULL) 1042 fatal("%s: no channel for id %d", __func__, id); 1043 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1044 fatal("%s: channel %d lacks control channel %d", __func__, 1045 id, c->ctl_chan); 1046 1047 if (!success) { 1048 debug3("%s: sending failure reply", __func__); 1049 /* prepare reply */ 1050 buffer_init(&reply); 1051 buffer_put_int(&reply, MUX_S_FAILURE); 1052 buffer_put_int(&reply, cctx->rid); 1053 buffer_put_cstring(&reply, "Session open refused by peer"); 1054 goto done; 1055 } 1056 1057 debug3("%s: sending success reply", __func__); 1058 /* prepare reply */ 1059 buffer_init(&reply); 1060 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1061 buffer_put_int(&reply, cctx->rid); 1062 buffer_put_int(&reply, c->self); 1063 1064 done: 1065 /* Send reply */ 1066 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1067 buffer_free(&reply); 1068 1069 if (cc->mux_pause <= 0) 1070 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1071 cc->mux_pause = 0; /* start processing messages again */ 1072 c->open_confirm_ctx = NULL; 1073 free(cctx); 1074 } 1075 1076 static int 1077 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1078 { 1079 debug("%s: channel %d: stop listening", __func__, c->self); 1080 1081 if (options.control_master == SSHCTL_MASTER_ASK || 1082 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1083 if (!ask_permission("Disable further multiplexing on shared " 1084 "connection to %s? ", host)) { 1085 debug2("%s: stop listen refused by user", __func__); 1086 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1087 buffer_put_int(r, rid); 1088 buffer_put_cstring(r, "Permission denied"); 1089 return 0; 1090 } 1091 } 1092 1093 if (mux_listener_channel != NULL) { 1094 channel_free(mux_listener_channel); 1095 client_stop_mux(); 1096 free(options.control_path); 1097 options.control_path = NULL; 1098 mux_listener_channel = NULL; 1099 muxserver_sock = -1; 1100 } 1101 1102 /* prepare reply */ 1103 buffer_put_int(r, MUX_S_OK); 1104 buffer_put_int(r, rid); 1105 1106 return 0; 1107 } 1108 1109 static int 1110 process_mux_proxy(u_int rid, Channel *c, Buffer *m, Buffer *r) 1111 { 1112 debug("%s: channel %d: proxy request", __func__, c->self); 1113 1114 c->mux_rcb = channel_proxy_downstream; 1115 buffer_put_int(r, MUX_S_PROXY); 1116 buffer_put_int(r, rid); 1117 1118 return 0; 1119 } 1120 1121 /* Channel callbacks fired on read/write from mux slave fd */ 1122 static int 1123 mux_master_read_cb(Channel *c) 1124 { 1125 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1126 Buffer in, out; 1127 const u_char *ptr; 1128 u_int type, rid, have, i; 1129 int ret = -1; 1130 1131 /* Setup ctx and */ 1132 if (c->mux_ctx == NULL) { 1133 state = xcalloc(1, sizeof(*state)); 1134 c->mux_ctx = state; 1135 channel_register_cleanup(c->self, 1136 mux_master_control_cleanup_cb, 0); 1137 1138 /* Send hello */ 1139 buffer_init(&out); 1140 buffer_put_int(&out, MUX_MSG_HELLO); 1141 buffer_put_int(&out, SSHMUX_VER); 1142 /* no extensions */ 1143 buffer_put_string(&c->output, buffer_ptr(&out), 1144 buffer_len(&out)); 1145 buffer_free(&out); 1146 debug3("%s: channel %d: hello sent", __func__, c->self); 1147 return 0; 1148 } 1149 1150 buffer_init(&in); 1151 buffer_init(&out); 1152 1153 /* Channel code ensures that we receive whole packets */ 1154 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1155 malf: 1156 error("%s: malformed message", __func__); 1157 goto out; 1158 } 1159 buffer_append(&in, ptr, have); 1160 1161 if (buffer_get_int_ret(&type, &in) != 0) 1162 goto malf; 1163 debug3("%s: channel %d packet type 0x%08x len %u", 1164 __func__, c->self, type, buffer_len(&in)); 1165 1166 if (type == MUX_MSG_HELLO) 1167 rid = 0; 1168 else { 1169 if (!state->hello_rcvd) { 1170 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1171 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1172 goto out; 1173 } 1174 if (buffer_get_int_ret(&rid, &in) != 0) 1175 goto malf; 1176 } 1177 1178 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1179 if (type == mux_master_handlers[i].type) { 1180 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1181 break; 1182 } 1183 } 1184 if (mux_master_handlers[i].handler == NULL) { 1185 error("%s: unsupported mux message 0x%08x", __func__, type); 1186 buffer_put_int(&out, MUX_S_FAILURE); 1187 buffer_put_int(&out, rid); 1188 buffer_put_cstring(&out, "unsupported request"); 1189 ret = 0; 1190 } 1191 /* Enqueue reply packet */ 1192 if (buffer_len(&out) != 0) { 1193 buffer_put_string(&c->output, buffer_ptr(&out), 1194 buffer_len(&out)); 1195 } 1196 out: 1197 buffer_free(&in); 1198 buffer_free(&out); 1199 return ret; 1200 } 1201 1202 void 1203 mux_exit_message(Channel *c, int exitval) 1204 { 1205 Buffer m; 1206 Channel *mux_chan; 1207 1208 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1209 exitval); 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_EXIT_MESSAGE); 1218 buffer_put_int(&m, c->self); 1219 buffer_put_int(&m, exitval); 1220 1221 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1222 buffer_free(&m); 1223 } 1224 1225 void 1226 mux_tty_alloc_failed(Channel *c) 1227 { 1228 Buffer m; 1229 Channel *mux_chan; 1230 1231 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1232 1233 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1234 fatal("%s: channel %d missing mux channel %d", 1235 __func__, c->self, c->ctl_chan); 1236 1237 /* Append exit message packet to control socket output queue */ 1238 buffer_init(&m); 1239 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1240 buffer_put_int(&m, c->self); 1241 1242 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1243 buffer_free(&m); 1244 } 1245 1246 /* Prepare a mux master to listen on a Unix domain socket. */ 1247 void 1248 muxserver_listen(void) 1249 { 1250 mode_t old_umask; 1251 char *orig_control_path = options.control_path; 1252 char rbuf[16+1]; 1253 u_int i, r; 1254 int oerrno; 1255 1256 if (options.control_path == NULL || 1257 options.control_master == SSHCTL_MASTER_NO) 1258 return; 1259 1260 debug("setting up multiplex master socket"); 1261 1262 /* 1263 * Use a temporary path before listen so we can pseudo-atomically 1264 * establish the listening socket in its final location to avoid 1265 * other processes racing in between bind() and listen() and hitting 1266 * an unready socket. 1267 */ 1268 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1269 r = arc4random_uniform(26+26+10); 1270 rbuf[i] = (r < 26) ? 'a' + r : 1271 (r < 26*2) ? 'A' + r - 26 : 1272 '0' + r - 26 - 26; 1273 } 1274 rbuf[sizeof(rbuf) - 1] = '\0'; 1275 options.control_path = NULL; 1276 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1277 debug3("%s: temporary control path %s", __func__, options.control_path); 1278 1279 old_umask = umask(0177); 1280 muxserver_sock = unix_listener(options.control_path, 64, 0); 1281 oerrno = errno; 1282 umask(old_umask); 1283 if (muxserver_sock < 0) { 1284 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1285 error("ControlSocket %s already exists, " 1286 "disabling multiplexing", options.control_path); 1287 disable_mux_master: 1288 if (muxserver_sock != -1) { 1289 close(muxserver_sock); 1290 muxserver_sock = -1; 1291 } 1292 free(orig_control_path); 1293 free(options.control_path); 1294 options.control_path = NULL; 1295 options.control_master = SSHCTL_MASTER_NO; 1296 return; 1297 } else { 1298 /* unix_listener() logs the error */ 1299 cleanup_exit(255); 1300 } 1301 } 1302 1303 /* Now atomically "move" the mux socket into position */ 1304 if (link(options.control_path, orig_control_path) != 0) { 1305 if (errno != EEXIST) { 1306 fatal("%s: link mux listener %s => %s: %s", __func__, 1307 options.control_path, orig_control_path, 1308 strerror(errno)); 1309 } 1310 error("ControlSocket %s already exists, disabling multiplexing", 1311 orig_control_path); 1312 unlink(options.control_path); 1313 goto disable_mux_master; 1314 } 1315 unlink(options.control_path); 1316 free(options.control_path); 1317 options.control_path = orig_control_path; 1318 1319 set_nonblock(muxserver_sock); 1320 1321 mux_listener_channel = channel_new("mux listener", 1322 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1323 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1324 0, options.control_path, 1); 1325 mux_listener_channel->mux_rcb = mux_master_read_cb; 1326 debug3("%s: mux listener channel %d fd %d", __func__, 1327 mux_listener_channel->self, mux_listener_channel->sock); 1328 } 1329 1330 /* Callback on open confirmation in mux master for a mux client session. */ 1331 static void 1332 mux_session_confirm(int id, int success, void *arg) 1333 { 1334 struct mux_session_confirm_ctx *cctx = arg; 1335 const char *display; 1336 Channel *c, *cc; 1337 int i; 1338 Buffer reply; 1339 1340 if (cctx == NULL) 1341 fatal("%s: cctx == NULL", __func__); 1342 if ((c = channel_by_id(id)) == NULL) 1343 fatal("%s: no channel for id %d", __func__, id); 1344 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1345 fatal("%s: channel %d lacks control channel %d", __func__, 1346 id, c->ctl_chan); 1347 1348 if (!success) { 1349 debug3("%s: sending failure reply", __func__); 1350 /* prepare reply */ 1351 buffer_init(&reply); 1352 buffer_put_int(&reply, MUX_S_FAILURE); 1353 buffer_put_int(&reply, cctx->rid); 1354 buffer_put_cstring(&reply, "Session open refused by peer"); 1355 goto done; 1356 } 1357 1358 display = getenv("DISPLAY"); 1359 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1360 char *proto, *data; 1361 1362 /* Get reasonable local authentication information. */ 1363 if (client_x11_get_proto(display, options.xauth_location, 1364 options.forward_x11_trusted, options.forward_x11_timeout, 1365 &proto, &data) == 0) { 1366 /* Request forwarding with authentication spoofing. */ 1367 debug("Requesting X11 forwarding with authentication " 1368 "spoofing."); 1369 x11_request_forwarding_with_spoofing(id, display, proto, 1370 data, 1); 1371 /* XXX exit_on_forward_failure */ 1372 client_expect_confirm(id, "X11 forwarding", 1373 CONFIRM_WARN); 1374 } 1375 } 1376 1377 if (cctx->want_agent_fwd && options.forward_agent) { 1378 debug("Requesting authentication agent forwarding."); 1379 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1380 packet_send(); 1381 } 1382 1383 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1384 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1385 1386 debug3("%s: sending success reply", __func__); 1387 /* prepare reply */ 1388 buffer_init(&reply); 1389 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1390 buffer_put_int(&reply, cctx->rid); 1391 buffer_put_int(&reply, c->self); 1392 1393 done: 1394 /* Send reply */ 1395 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1396 buffer_free(&reply); 1397 1398 if (cc->mux_pause <= 0) 1399 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1400 cc->mux_pause = 0; /* start processing messages again */ 1401 c->open_confirm_ctx = NULL; 1402 buffer_free(&cctx->cmd); 1403 free(cctx->term); 1404 if (cctx->env != NULL) { 1405 for (i = 0; cctx->env[i] != NULL; i++) 1406 free(cctx->env[i]); 1407 free(cctx->env); 1408 } 1409 free(cctx); 1410 } 1411 1412 /* ** Multiplexing client support */ 1413 1414 /* Exit signal handler */ 1415 static void 1416 control_client_sighandler(int signo) 1417 { 1418 muxclient_terminate = signo; 1419 } 1420 1421 /* 1422 * Relay signal handler - used to pass some signals from mux client to 1423 * mux master. 1424 */ 1425 static void 1426 control_client_sigrelay(int signo) 1427 { 1428 int save_errno = errno; 1429 1430 if (muxserver_pid > 1) 1431 kill(muxserver_pid, signo); 1432 1433 errno = save_errno; 1434 } 1435 1436 static int 1437 mux_client_read(int fd, Buffer *b, u_int need) 1438 { 1439 u_int have; 1440 ssize_t len; 1441 u_char *p; 1442 struct pollfd pfd; 1443 1444 pfd.fd = fd; 1445 pfd.events = POLLIN; 1446 p = buffer_append_space(b, need); 1447 for (have = 0; have < need; ) { 1448 if (muxclient_terminate) { 1449 errno = EINTR; 1450 return -1; 1451 } 1452 len = read(fd, p + have, need - have); 1453 if (len < 0) { 1454 switch (errno) { 1455 case EAGAIN: 1456 (void)poll(&pfd, 1, -1); 1457 /* FALLTHROUGH */ 1458 case EINTR: 1459 continue; 1460 default: 1461 return -1; 1462 } 1463 } 1464 if (len == 0) { 1465 errno = EPIPE; 1466 return -1; 1467 } 1468 have += (u_int)len; 1469 } 1470 return 0; 1471 } 1472 1473 static int 1474 mux_client_write_packet(int fd, Buffer *m) 1475 { 1476 Buffer queue; 1477 u_int have, need; 1478 int oerrno, len; 1479 u_char *ptr; 1480 struct pollfd pfd; 1481 1482 pfd.fd = fd; 1483 pfd.events = POLLOUT; 1484 buffer_init(&queue); 1485 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1486 1487 need = buffer_len(&queue); 1488 ptr = buffer_ptr(&queue); 1489 1490 for (have = 0; have < need; ) { 1491 if (muxclient_terminate) { 1492 buffer_free(&queue); 1493 errno = EINTR; 1494 return -1; 1495 } 1496 len = write(fd, ptr + have, need - have); 1497 if (len < 0) { 1498 switch (errno) { 1499 case EAGAIN: 1500 (void)poll(&pfd, 1, -1); 1501 /* FALLTHROUGH */ 1502 case EINTR: 1503 continue; 1504 default: 1505 oerrno = errno; 1506 buffer_free(&queue); 1507 errno = oerrno; 1508 return -1; 1509 } 1510 } 1511 if (len == 0) { 1512 buffer_free(&queue); 1513 errno = EPIPE; 1514 return -1; 1515 } 1516 have += (u_int)len; 1517 } 1518 buffer_free(&queue); 1519 return 0; 1520 } 1521 1522 static int 1523 mux_client_read_packet(int fd, Buffer *m) 1524 { 1525 Buffer queue; 1526 u_int need, have; 1527 const u_char *ptr; 1528 int oerrno; 1529 1530 buffer_init(&queue); 1531 if (mux_client_read(fd, &queue, 4) != 0) { 1532 if ((oerrno = errno) == EPIPE) 1533 debug3("%s: read header failed: %s", __func__, 1534 strerror(errno)); 1535 buffer_free(&queue); 1536 errno = oerrno; 1537 return -1; 1538 } 1539 need = get_u32(buffer_ptr(&queue)); 1540 if (mux_client_read(fd, &queue, need) != 0) { 1541 oerrno = errno; 1542 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1543 buffer_free(&queue); 1544 errno = oerrno; 1545 return -1; 1546 } 1547 ptr = buffer_get_string_ptr(&queue, &have); 1548 buffer_append(m, ptr, have); 1549 buffer_free(&queue); 1550 return 0; 1551 } 1552 1553 static int 1554 mux_client_hello_exchange(int fd) 1555 { 1556 Buffer m; 1557 u_int type, ver; 1558 1559 buffer_init(&m); 1560 buffer_put_int(&m, MUX_MSG_HELLO); 1561 buffer_put_int(&m, SSHMUX_VER); 1562 /* no extensions */ 1563 1564 if (mux_client_write_packet(fd, &m) != 0) 1565 fatal("%s: write packet: %s", __func__, strerror(errno)); 1566 1567 buffer_clear(&m); 1568 1569 /* Read their HELLO */ 1570 if (mux_client_read_packet(fd, &m) != 0) { 1571 buffer_free(&m); 1572 return -1; 1573 } 1574 1575 type = buffer_get_int(&m); 1576 if (type != MUX_MSG_HELLO) 1577 fatal("%s: expected HELLO (%u) received %u", 1578 __func__, MUX_MSG_HELLO, type); 1579 ver = buffer_get_int(&m); 1580 if (ver != SSHMUX_VER) 1581 fatal("Unsupported multiplexing protocol version %d " 1582 "(expected %d)", ver, SSHMUX_VER); 1583 debug2("%s: master version %u", __func__, ver); 1584 /* No extensions are presently defined */ 1585 while (buffer_len(&m) > 0) { 1586 char *name = buffer_get_string(&m, NULL); 1587 char *value = buffer_get_string(&m, NULL); 1588 1589 debug2("Unrecognised master extension \"%s\"", name); 1590 free(name); 1591 free(value); 1592 } 1593 buffer_free(&m); 1594 return 0; 1595 } 1596 1597 static u_int 1598 mux_client_request_alive(int fd) 1599 { 1600 Buffer m; 1601 char *e; 1602 u_int pid, type, rid; 1603 1604 debug3("%s: entering", __func__); 1605 1606 buffer_init(&m); 1607 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1608 buffer_put_int(&m, muxclient_request_id); 1609 1610 if (mux_client_write_packet(fd, &m) != 0) 1611 fatal("%s: write packet: %s", __func__, strerror(errno)); 1612 1613 buffer_clear(&m); 1614 1615 /* Read their reply */ 1616 if (mux_client_read_packet(fd, &m) != 0) { 1617 buffer_free(&m); 1618 return 0; 1619 } 1620 1621 type = buffer_get_int(&m); 1622 if (type != MUX_S_ALIVE) { 1623 e = buffer_get_string(&m, NULL); 1624 fatal("%s: master returned error: %s", __func__, e); 1625 } 1626 1627 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1628 fatal("%s: out of sequence reply: my id %u theirs %u", 1629 __func__, muxclient_request_id, rid); 1630 pid = buffer_get_int(&m); 1631 buffer_free(&m); 1632 1633 debug3("%s: done pid = %u", __func__, pid); 1634 1635 muxclient_request_id++; 1636 1637 return pid; 1638 } 1639 1640 static void 1641 mux_client_request_terminate(int fd) 1642 { 1643 Buffer m; 1644 char *e; 1645 u_int type, rid; 1646 1647 debug3("%s: entering", __func__); 1648 1649 buffer_init(&m); 1650 buffer_put_int(&m, MUX_C_TERMINATE); 1651 buffer_put_int(&m, muxclient_request_id); 1652 1653 if (mux_client_write_packet(fd, &m) != 0) 1654 fatal("%s: write packet: %s", __func__, strerror(errno)); 1655 1656 buffer_clear(&m); 1657 1658 /* Read their reply */ 1659 if (mux_client_read_packet(fd, &m) != 0) { 1660 /* Remote end exited already */ 1661 if (errno == EPIPE) { 1662 buffer_free(&m); 1663 return; 1664 } 1665 fatal("%s: read from master failed: %s", 1666 __func__, strerror(errno)); 1667 } 1668 1669 type = buffer_get_int(&m); 1670 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1671 fatal("%s: out of sequence reply: my id %u theirs %u", 1672 __func__, muxclient_request_id, rid); 1673 switch (type) { 1674 case MUX_S_OK: 1675 break; 1676 case MUX_S_PERMISSION_DENIED: 1677 e = buffer_get_string(&m, NULL); 1678 fatal("Master refused termination request: %s", e); 1679 case MUX_S_FAILURE: 1680 e = buffer_get_string(&m, NULL); 1681 fatal("%s: termination request failed: %s", __func__, e); 1682 default: 1683 fatal("%s: unexpected response from master 0x%08x", 1684 __func__, type); 1685 } 1686 buffer_free(&m); 1687 muxclient_request_id++; 1688 } 1689 1690 static int 1691 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1692 { 1693 Buffer m; 1694 char *e, *fwd_desc; 1695 u_int type, rid; 1696 1697 fwd_desc = format_forward(ftype, fwd); 1698 debug("Requesting %s %s", 1699 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1700 free(fwd_desc); 1701 1702 buffer_init(&m); 1703 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1704 buffer_put_int(&m, muxclient_request_id); 1705 buffer_put_int(&m, ftype); 1706 if (fwd->listen_path != NULL) { 1707 buffer_put_cstring(&m, fwd->listen_path); 1708 } else { 1709 buffer_put_cstring(&m, 1710 fwd->listen_host == NULL ? "" : 1711 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1712 } 1713 buffer_put_int(&m, fwd->listen_port); 1714 if (fwd->connect_path != NULL) { 1715 buffer_put_cstring(&m, fwd->connect_path); 1716 } else { 1717 buffer_put_cstring(&m, 1718 fwd->connect_host == NULL ? "" : fwd->connect_host); 1719 } 1720 buffer_put_int(&m, fwd->connect_port); 1721 1722 if (mux_client_write_packet(fd, &m) != 0) 1723 fatal("%s: write packet: %s", __func__, strerror(errno)); 1724 1725 buffer_clear(&m); 1726 1727 /* Read their reply */ 1728 if (mux_client_read_packet(fd, &m) != 0) { 1729 buffer_free(&m); 1730 return -1; 1731 } 1732 1733 type = buffer_get_int(&m); 1734 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1735 fatal("%s: out of sequence reply: my id %u theirs %u", 1736 __func__, muxclient_request_id, rid); 1737 switch (type) { 1738 case MUX_S_OK: 1739 break; 1740 case MUX_S_REMOTE_PORT: 1741 if (cancel_flag) 1742 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1743 fwd->allocated_port = buffer_get_int(&m); 1744 verbose("Allocated port %u for remote forward to %s:%d", 1745 fwd->allocated_port, 1746 fwd->connect_host ? fwd->connect_host : "", 1747 fwd->connect_port); 1748 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1749 fprintf(stdout, "%i\n", fwd->allocated_port); 1750 break; 1751 case MUX_S_PERMISSION_DENIED: 1752 e = buffer_get_string(&m, NULL); 1753 buffer_free(&m); 1754 error("Master refused forwarding request: %s", e); 1755 return -1; 1756 case MUX_S_FAILURE: 1757 e = buffer_get_string(&m, NULL); 1758 buffer_free(&m); 1759 error("%s: forwarding request failed: %s", __func__, e); 1760 return -1; 1761 default: 1762 fatal("%s: unexpected response from master 0x%08x", 1763 __func__, type); 1764 } 1765 buffer_free(&m); 1766 1767 muxclient_request_id++; 1768 return 0; 1769 } 1770 1771 static int 1772 mux_client_forwards(int fd, int cancel_flag) 1773 { 1774 int i, ret = 0; 1775 1776 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1777 cancel_flag ? "cancel" : "request", 1778 options.num_local_forwards, options.num_remote_forwards); 1779 1780 /* XXX ExitOnForwardingFailure */ 1781 for (i = 0; i < options.num_local_forwards; i++) { 1782 if (mux_client_forward(fd, cancel_flag, 1783 options.local_forwards[i].connect_port == 0 ? 1784 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1785 options.local_forwards + i) != 0) 1786 ret = -1; 1787 } 1788 for (i = 0; i < options.num_remote_forwards; i++) { 1789 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1790 options.remote_forwards + i) != 0) 1791 ret = -1; 1792 } 1793 return ret; 1794 } 1795 1796 static int 1797 mux_client_request_session(int fd) 1798 { 1799 Buffer m; 1800 char *e, *term; 1801 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1802 extern char **environ; 1803 int devnull, rawmode; 1804 1805 debug3("%s: entering", __func__); 1806 1807 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1808 error("%s: master alive request failed", __func__); 1809 return -1; 1810 } 1811 1812 signal(SIGPIPE, SIG_IGN); 1813 1814 if (stdin_null_flag) { 1815 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1816 fatal("open(/dev/null): %s", strerror(errno)); 1817 if (dup2(devnull, STDIN_FILENO) == -1) 1818 fatal("dup2: %s", strerror(errno)); 1819 if (devnull > STDERR_FILENO) 1820 close(devnull); 1821 } 1822 1823 term = getenv("TERM"); 1824 1825 buffer_init(&m); 1826 buffer_put_int(&m, MUX_C_NEW_SESSION); 1827 buffer_put_int(&m, muxclient_request_id); 1828 buffer_put_cstring(&m, ""); /* reserved */ 1829 buffer_put_int(&m, tty_flag); 1830 buffer_put_int(&m, options.forward_x11); 1831 buffer_put_int(&m, options.forward_agent); 1832 buffer_put_int(&m, subsystem_flag); 1833 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1834 0xffffffff : (u_int)options.escape_char); 1835 buffer_put_cstring(&m, term == NULL ? "" : term); 1836 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1837 1838 if (options.num_send_env > 0 && environ != NULL) { 1839 /* Pass environment */ 1840 for (i = 0; environ[i] != NULL; i++) { 1841 if (env_permitted(environ[i])) { 1842 buffer_put_cstring(&m, environ[i]); 1843 } 1844 } 1845 } 1846 1847 if (mux_client_write_packet(fd, &m) != 0) 1848 fatal("%s: write packet: %s", __func__, strerror(errno)); 1849 1850 /* Send the stdio file descriptors */ 1851 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1852 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1853 mm_send_fd(fd, STDERR_FILENO) == -1) 1854 fatal("%s: send fds failed", __func__); 1855 1856 debug3("%s: session request sent", __func__); 1857 1858 /* Read their reply */ 1859 buffer_clear(&m); 1860 if (mux_client_read_packet(fd, &m) != 0) { 1861 error("%s: read from master failed: %s", 1862 __func__, strerror(errno)); 1863 buffer_free(&m); 1864 return -1; 1865 } 1866 1867 type = buffer_get_int(&m); 1868 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1869 fatal("%s: out of sequence reply: my id %u theirs %u", 1870 __func__, muxclient_request_id, rid); 1871 switch (type) { 1872 case MUX_S_SESSION_OPENED: 1873 sid = buffer_get_int(&m); 1874 debug("%s: master session id: %u", __func__, sid); 1875 break; 1876 case MUX_S_PERMISSION_DENIED: 1877 e = buffer_get_string(&m, NULL); 1878 buffer_free(&m); 1879 error("Master refused session request: %s", e); 1880 return -1; 1881 case MUX_S_FAILURE: 1882 e = buffer_get_string(&m, NULL); 1883 buffer_free(&m); 1884 error("%s: session request failed: %s", __func__, e); 1885 return -1; 1886 default: 1887 buffer_free(&m); 1888 error("%s: unexpected response from master 0x%08x", 1889 __func__, type); 1890 return -1; 1891 } 1892 muxclient_request_id++; 1893 1894 #ifdef __OpenBSD__ 1895 if (pledge("stdio proc tty", NULL) == -1) 1896 fatal("%s pledge(): %s", __func__, strerror(errno)); 1897 #endif 1898 1899 signal(SIGHUP, control_client_sighandler); 1900 signal(SIGINT, control_client_sighandler); 1901 signal(SIGTERM, control_client_sighandler); 1902 signal(SIGWINCH, control_client_sigrelay); 1903 1904 rawmode = tty_flag; 1905 if (tty_flag) 1906 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1907 1908 /* 1909 * Stick around until the controlee closes the client_fd. 1910 * Before it does, it is expected to write an exit message. 1911 * This process must read the value and wait for the closure of 1912 * the client_fd; if this one closes early, the multiplex master will 1913 * terminate early too (possibly losing data). 1914 */ 1915 for (exitval = 255, exitval_seen = 0;;) { 1916 buffer_clear(&m); 1917 if (mux_client_read_packet(fd, &m) != 0) 1918 break; 1919 type = buffer_get_int(&m); 1920 switch (type) { 1921 case MUX_S_TTY_ALLOC_FAIL: 1922 if ((esid = buffer_get_int(&m)) != sid) 1923 fatal("%s: tty alloc fail on unknown session: " 1924 "my id %u theirs %u", 1925 __func__, sid, esid); 1926 leave_raw_mode(options.request_tty == 1927 REQUEST_TTY_FORCE); 1928 rawmode = 0; 1929 continue; 1930 case MUX_S_EXIT_MESSAGE: 1931 if ((esid = buffer_get_int(&m)) != sid) 1932 fatal("%s: exit on unknown session: " 1933 "my id %u theirs %u", 1934 __func__, sid, esid); 1935 if (exitval_seen) 1936 fatal("%s: exitval sent twice", __func__); 1937 exitval = buffer_get_int(&m); 1938 exitval_seen = 1; 1939 continue; 1940 default: 1941 e = buffer_get_string(&m, NULL); 1942 fatal("%s: master returned error: %s", __func__, e); 1943 } 1944 } 1945 1946 close(fd); 1947 if (rawmode) 1948 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1949 1950 if (muxclient_terminate) { 1951 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1952 exitval = 255; 1953 } else if (!exitval_seen) { 1954 debug2("Control master terminated unexpectedly"); 1955 exitval = 255; 1956 } else 1957 debug2("Received exit status from master %d", exitval); 1958 1959 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1960 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1961 1962 exit(exitval); 1963 } 1964 1965 static int 1966 mux_client_proxy(int fd) 1967 { 1968 Buffer m; 1969 char *e; 1970 u_int type, rid; 1971 1972 buffer_init(&m); 1973 buffer_put_int(&m, MUX_C_PROXY); 1974 buffer_put_int(&m, muxclient_request_id); 1975 if (mux_client_write_packet(fd, &m) != 0) 1976 fatal("%s: write packet: %s", __func__, strerror(errno)); 1977 1978 buffer_clear(&m); 1979 1980 /* Read their reply */ 1981 if (mux_client_read_packet(fd, &m) != 0) { 1982 buffer_free(&m); 1983 return 0; 1984 } 1985 type = buffer_get_int(&m); 1986 if (type != MUX_S_PROXY) { 1987 e = buffer_get_string(&m, NULL); 1988 fatal("%s: master returned error: %s", __func__, e); 1989 } 1990 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1991 fatal("%s: out of sequence reply: my id %u theirs %u", 1992 __func__, muxclient_request_id, rid); 1993 buffer_free(&m); 1994 1995 debug3("%s: done", __func__); 1996 muxclient_request_id++; 1997 return 0; 1998 } 1999 2000 static int 2001 mux_client_request_stdio_fwd(int fd) 2002 { 2003 Buffer m; 2004 char *e; 2005 u_int type, rid, sid; 2006 int devnull; 2007 2008 debug3("%s: entering", __func__); 2009 2010 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2011 error("%s: master alive request failed", __func__); 2012 return -1; 2013 } 2014 2015 signal(SIGPIPE, SIG_IGN); 2016 2017 if (stdin_null_flag) { 2018 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 2019 fatal("open(/dev/null): %s", strerror(errno)); 2020 if (dup2(devnull, STDIN_FILENO) == -1) 2021 fatal("dup2: %s", strerror(errno)); 2022 if (devnull > STDERR_FILENO) 2023 close(devnull); 2024 } 2025 2026 buffer_init(&m); 2027 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 2028 buffer_put_int(&m, muxclient_request_id); 2029 buffer_put_cstring(&m, ""); /* reserved */ 2030 buffer_put_cstring(&m, options.stdio_forward_host); 2031 buffer_put_int(&m, options.stdio_forward_port); 2032 2033 if (mux_client_write_packet(fd, &m) != 0) 2034 fatal("%s: write packet: %s", __func__, strerror(errno)); 2035 2036 /* Send the stdio file descriptors */ 2037 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2038 mm_send_fd(fd, STDOUT_FILENO) == -1) 2039 fatal("%s: send fds failed", __func__); 2040 2041 #ifdef __OpenBSD__ 2042 if (pledge("stdio proc tty", NULL) == -1) 2043 fatal("%s pledge(): %s", __func__, strerror(errno)); 2044 #endif 2045 2046 debug3("%s: stdio forward request sent", __func__); 2047 2048 /* Read their reply */ 2049 buffer_clear(&m); 2050 2051 if (mux_client_read_packet(fd, &m) != 0) { 2052 error("%s: read from master failed: %s", 2053 __func__, strerror(errno)); 2054 buffer_free(&m); 2055 return -1; 2056 } 2057 2058 type = buffer_get_int(&m); 2059 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2060 fatal("%s: out of sequence reply: my id %u theirs %u", 2061 __func__, muxclient_request_id, rid); 2062 switch (type) { 2063 case MUX_S_SESSION_OPENED: 2064 sid = buffer_get_int(&m); 2065 debug("%s: master session id: %u", __func__, sid); 2066 break; 2067 case MUX_S_PERMISSION_DENIED: 2068 e = buffer_get_string(&m, NULL); 2069 buffer_free(&m); 2070 fatal("Master refused stdio forwarding request: %s", e); 2071 case MUX_S_FAILURE: 2072 e = buffer_get_string(&m, NULL); 2073 buffer_free(&m); 2074 fatal("Stdio forwarding request failed: %s", e); 2075 default: 2076 buffer_free(&m); 2077 error("%s: unexpected response from master 0x%08x", 2078 __func__, type); 2079 return -1; 2080 } 2081 muxclient_request_id++; 2082 2083 signal(SIGHUP, control_client_sighandler); 2084 signal(SIGINT, control_client_sighandler); 2085 signal(SIGTERM, control_client_sighandler); 2086 signal(SIGWINCH, control_client_sigrelay); 2087 2088 /* 2089 * Stick around until the controlee closes the client_fd. 2090 */ 2091 buffer_clear(&m); 2092 if (mux_client_read_packet(fd, &m) != 0) { 2093 if (errno == EPIPE || 2094 (errno == EINTR && muxclient_terminate != 0)) 2095 return 0; 2096 fatal("%s: mux_client_read_packet: %s", 2097 __func__, strerror(errno)); 2098 } 2099 fatal("%s: master returned unexpected message %u", __func__, type); 2100 } 2101 2102 static void 2103 mux_client_request_stop_listening(int fd) 2104 { 2105 Buffer m; 2106 char *e; 2107 u_int type, rid; 2108 2109 debug3("%s: entering", __func__); 2110 2111 buffer_init(&m); 2112 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2113 buffer_put_int(&m, muxclient_request_id); 2114 2115 if (mux_client_write_packet(fd, &m) != 0) 2116 fatal("%s: write packet: %s", __func__, strerror(errno)); 2117 2118 buffer_clear(&m); 2119 2120 /* Read their reply */ 2121 if (mux_client_read_packet(fd, &m) != 0) 2122 fatal("%s: read from master failed: %s", 2123 __func__, strerror(errno)); 2124 2125 type = buffer_get_int(&m); 2126 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2127 fatal("%s: out of sequence reply: my id %u theirs %u", 2128 __func__, muxclient_request_id, rid); 2129 switch (type) { 2130 case MUX_S_OK: 2131 break; 2132 case MUX_S_PERMISSION_DENIED: 2133 e = buffer_get_string(&m, NULL); 2134 fatal("Master refused stop listening request: %s", e); 2135 case MUX_S_FAILURE: 2136 e = buffer_get_string(&m, NULL); 2137 fatal("%s: stop listening request failed: %s", __func__, e); 2138 default: 2139 fatal("%s: unexpected response from master 0x%08x", 2140 __func__, type); 2141 } 2142 buffer_free(&m); 2143 muxclient_request_id++; 2144 } 2145 2146 /* Multiplex client main loop. */ 2147 int 2148 muxclient(const char *path) 2149 { 2150 struct sockaddr_un addr; 2151 int sock; 2152 u_int pid; 2153 2154 if (muxclient_command == 0) { 2155 if (options.stdio_forward_host != NULL) 2156 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2157 else 2158 muxclient_command = SSHMUX_COMMAND_OPEN; 2159 } 2160 2161 switch (options.control_master) { 2162 case SSHCTL_MASTER_AUTO: 2163 case SSHCTL_MASTER_AUTO_ASK: 2164 debug("auto-mux: Trying existing master"); 2165 /* FALLTHROUGH */ 2166 case SSHCTL_MASTER_NO: 2167 break; 2168 default: 2169 return -1; 2170 } 2171 2172 memset(&addr, '\0', sizeof(addr)); 2173 addr.sun_family = AF_UNIX; 2174 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 2175 strlen(path) + 1; 2176 2177 if (strlcpy(addr.sun_path, path, 2178 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2179 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2180 (unsigned int)sizeof(addr.sun_path)); 2181 2182 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2183 fatal("%s socket(): %s", __func__, strerror(errno)); 2184 2185 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 2186 switch (muxclient_command) { 2187 case SSHMUX_COMMAND_OPEN: 2188 case SSHMUX_COMMAND_STDIO_FWD: 2189 break; 2190 default: 2191 fatal("Control socket connect(%.100s): %s", path, 2192 strerror(errno)); 2193 } 2194 if (errno == ECONNREFUSED && 2195 options.control_master != SSHCTL_MASTER_NO) { 2196 debug("Stale control socket %.100s, unlinking", path); 2197 unlink(path); 2198 } else if (errno == ENOENT) { 2199 debug("Control socket \"%.100s\" does not exist", path); 2200 } else { 2201 error("Control socket connect(%.100s): %s", path, 2202 strerror(errno)); 2203 } 2204 close(sock); 2205 return -1; 2206 } 2207 set_nonblock(sock); 2208 2209 if (mux_client_hello_exchange(sock) != 0) { 2210 error("%s: master hello exchange failed", __func__); 2211 close(sock); 2212 return -1; 2213 } 2214 2215 switch (muxclient_command) { 2216 case SSHMUX_COMMAND_ALIVE_CHECK: 2217 if ((pid = mux_client_request_alive(sock)) == 0) 2218 fatal("%s: master alive check failed", __func__); 2219 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2220 exit(0); 2221 case SSHMUX_COMMAND_TERMINATE: 2222 mux_client_request_terminate(sock); 2223 if (options.log_level != SYSLOG_LEVEL_QUIET) 2224 fprintf(stderr, "Exit request sent.\r\n"); 2225 exit(0); 2226 case SSHMUX_COMMAND_FORWARD: 2227 if (mux_client_forwards(sock, 0) != 0) 2228 fatal("%s: master forward request failed", __func__); 2229 exit(0); 2230 case SSHMUX_COMMAND_OPEN: 2231 if (mux_client_forwards(sock, 0) != 0) { 2232 error("%s: master forward request failed", __func__); 2233 return -1; 2234 } 2235 mux_client_request_session(sock); 2236 return -1; 2237 case SSHMUX_COMMAND_STDIO_FWD: 2238 mux_client_request_stdio_fwd(sock); 2239 exit(0); 2240 case SSHMUX_COMMAND_STOP: 2241 mux_client_request_stop_listening(sock); 2242 if (options.log_level != SYSLOG_LEVEL_QUIET) 2243 fprintf(stderr, "Stop listening request sent.\r\n"); 2244 exit(0); 2245 case SSHMUX_COMMAND_CANCEL_FWD: 2246 if (mux_client_forwards(sock, 1) != 0) 2247 error("%s: master cancel forward request failed", 2248 __func__); 2249 exit(0); 2250 case SSHMUX_COMMAND_PROXY: 2251 mux_client_proxy(sock); 2252 return (sock); 2253 default: 2254 fatal("unrecognised muxclient_command %d", muxclient_command); 2255 } 2256 } 2257