1 /* $NetBSD: mux.c,v 1.10 2014/10/19 16:30:58 christos Exp $ */ 2 /* $OpenBSD: mux.c,v 1.48 2014/07/17 07:22:19 djm Exp $ */ 3 /* 4 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 /* ssh session multiplexing support */ 20 21 /* 22 * TODO: 23 * - Better signalling from master to slave, especially passing of 24 * error messages 25 * - Better fall-back from mux slave error to new connection. 26 * - ExitOnForwardingFailure 27 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 28 * - Support ~^Z in mux slaves. 29 * - Inspect or control sessions in master. 30 * - If we ever support the "signal" channel request, send signals on 31 * sessions in master. 32 */ 33 34 #include "includes.h" 35 __RCSID("$NetBSD: mux.c,v 1.10 2014/10/19 16:30:58 christos Exp $"); 36 #include <sys/types.h> 37 #include <sys/param.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 = xrealloc(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 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 589 goto fail; 590 } 591 rfwd = &options.remote_forwards[fctx->fid]; 592 debug("%s: %s for: listen %d, connect %s:%d", __func__, 593 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 594 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 595 rfwd->connect_host, rfwd->connect_port); 596 if (type == SSH2_MSG_REQUEST_SUCCESS) { 597 if (rfwd->listen_port == 0) { 598 rfwd->allocated_port = packet_get_int(); 599 logit("Allocated port %u for mux remote forward" 600 " to %s:%d", rfwd->allocated_port, 601 rfwd->connect_host, rfwd->connect_port); 602 buffer_put_int(&out, MUX_S_REMOTE_PORT); 603 buffer_put_int(&out, fctx->rid); 604 buffer_put_int(&out, rfwd->allocated_port); 605 channel_update_permitted_opens(rfwd->handle, 606 rfwd->allocated_port); 607 } else { 608 buffer_put_int(&out, MUX_S_OK); 609 buffer_put_int(&out, fctx->rid); 610 } 611 goto out; 612 } else { 613 if (rfwd->listen_port == 0) 614 channel_update_permitted_opens(rfwd->handle, -1); 615 if (rfwd->listen_path != NULL) 616 xasprintf(&failmsg, "remote port forwarding failed for " 617 "listen path %s", rfwd->listen_path); 618 else 619 xasprintf(&failmsg, "remote port forwarding failed for " 620 "listen port %d", rfwd->listen_port); 621 } 622 fail: 623 error("%s: %s", __func__, failmsg); 624 buffer_put_int(&out, MUX_S_FAILURE); 625 buffer_put_int(&out, fctx->rid); 626 buffer_put_cstring(&out, failmsg); 627 free(failmsg); 628 out: 629 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 630 buffer_free(&out); 631 if (c->mux_pause <= 0) 632 fatal("%s: mux_pause %d", __func__, c->mux_pause); 633 c->mux_pause = 0; /* start processing messages again */ 634 } 635 636 static int 637 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 638 { 639 struct Forward fwd; 640 char *fwd_desc = NULL; 641 char *listen_addr, *connect_addr; 642 u_int ftype; 643 u_int lport, cport; 644 int i, ret = 0, freefwd = 1; 645 646 /* XXX - lport/cport check redundant */ 647 if (buffer_get_int_ret(&ftype, m) != 0 || 648 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 649 buffer_get_int_ret(&lport, m) != 0 || 650 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 651 buffer_get_int_ret(&cport, m) != 0 || 652 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 653 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 654 error("%s: malformed message", __func__); 655 ret = -1; 656 goto out; 657 } 658 if (*listen_addr == '\0') { 659 free(listen_addr); 660 listen_addr = NULL; 661 } 662 if (*connect_addr == '\0') { 663 free(connect_addr); 664 connect_addr = NULL; 665 } 666 667 memset(&fwd, 0, sizeof(fwd)); 668 fwd.listen_port = lport; 669 if (fwd.listen_port == PORT_STREAMLOCAL) 670 fwd.listen_path = listen_addr; 671 else 672 fwd.listen_host = listen_addr; 673 fwd.connect_port = cport; 674 if (fwd.connect_port == PORT_STREAMLOCAL) 675 fwd.connect_path = connect_addr; 676 else 677 fwd.connect_host = connect_addr; 678 679 debug2("%s: channel %d: request %s", __func__, c->self, 680 (fwd_desc = format_forward(ftype, &fwd))); 681 682 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 683 ftype != MUX_FWD_DYNAMIC) { 684 logit("%s: invalid forwarding type %u", __func__, ftype); 685 invalid: 686 free(listen_addr); 687 free(connect_addr); 688 buffer_put_int(r, MUX_S_FAILURE); 689 buffer_put_int(r, rid); 690 buffer_put_cstring(r, "Invalid forwarding request"); 691 return 0; 692 } 693 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 694 logit("%s: streamlocal and dynamic forwards " 695 "are mutually exclusive", __func__); 696 goto invalid; 697 } 698 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 699 logit("%s: invalid listen port %u", __func__, 700 fwd.listen_port); 701 goto invalid; 702 } 703 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 704 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 705 logit("%s: invalid connect port %u", __func__, 706 fwd.connect_port); 707 goto invalid; 708 } 709 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 710 logit("%s: missing connect host", __func__); 711 goto invalid; 712 } 713 714 /* Skip forwards that have already been requested */ 715 switch (ftype) { 716 case MUX_FWD_LOCAL: 717 case MUX_FWD_DYNAMIC: 718 for (i = 0; i < options.num_local_forwards; i++) { 719 if (compare_forward(&fwd, 720 options.local_forwards + i)) { 721 exists: 722 debug2("%s: found existing forwarding", 723 __func__); 724 buffer_put_int(r, MUX_S_OK); 725 buffer_put_int(r, rid); 726 goto out; 727 } 728 } 729 break; 730 case MUX_FWD_REMOTE: 731 for (i = 0; i < options.num_remote_forwards; i++) { 732 if (compare_forward(&fwd, 733 options.remote_forwards + i)) { 734 if (fwd.listen_port != 0) 735 goto exists; 736 debug2("%s: found allocated port", 737 __func__); 738 buffer_put_int(r, MUX_S_REMOTE_PORT); 739 buffer_put_int(r, rid); 740 buffer_put_int(r, 741 options.remote_forwards[i].allocated_port); 742 goto out; 743 } 744 } 745 break; 746 } 747 748 if (options.control_master == SSHCTL_MASTER_ASK || 749 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 750 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 751 debug2("%s: forwarding refused by user", __func__); 752 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 753 buffer_put_int(r, rid); 754 buffer_put_cstring(r, "Permission denied"); 755 goto out; 756 } 757 } 758 759 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 760 if (!channel_setup_local_fwd_listener(&fwd, 761 &options.fwd_opts)) { 762 fail: 763 logit("slave-requested %s failed", fwd_desc); 764 buffer_put_int(r, MUX_S_FAILURE); 765 buffer_put_int(r, rid); 766 buffer_put_cstring(r, "Port forwarding failed"); 767 goto out; 768 } 769 add_local_forward(&options, &fwd); 770 freefwd = 0; 771 } else { 772 struct mux_channel_confirm_ctx *fctx; 773 774 fwd.handle = channel_request_remote_forwarding(&fwd); 775 if (fwd.handle < 0) 776 goto fail; 777 add_remote_forward(&options, &fwd); 778 fctx = xcalloc(1, sizeof(*fctx)); 779 fctx->cid = c->self; 780 fctx->rid = rid; 781 fctx->fid = options.num_remote_forwards - 1; 782 client_register_global_confirm(mux_confirm_remote_forward, 783 fctx); 784 freefwd = 0; 785 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 786 /* delayed reply in mux_confirm_remote_forward */ 787 goto out; 788 } 789 buffer_put_int(r, MUX_S_OK); 790 buffer_put_int(r, rid); 791 out: 792 free(fwd_desc); 793 if (freefwd) { 794 free(fwd.listen_host); 795 free(fwd.listen_path); 796 free(fwd.connect_host); 797 free(fwd.connect_path); 798 } 799 return ret; 800 } 801 802 static int 803 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 804 { 805 struct Forward fwd, *found_fwd; 806 char *fwd_desc = NULL; 807 const char *error_reason = NULL; 808 char *listen_addr = NULL, *connect_addr = NULL; 809 u_int ftype; 810 int i, ret = 0; 811 u_int lport, cport; 812 813 if (buffer_get_int_ret(&ftype, m) != 0 || 814 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 815 buffer_get_int_ret(&lport, m) != 0 || 816 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 817 buffer_get_int_ret(&cport, m) != 0 || 818 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 819 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 820 error("%s: malformed message", __func__); 821 ret = -1; 822 goto out; 823 } 824 825 if (*listen_addr == '\0') { 826 free(listen_addr); 827 listen_addr = NULL; 828 } 829 if (*connect_addr == '\0') { 830 free(connect_addr); 831 connect_addr = NULL; 832 } 833 834 memset(&fwd, 0, sizeof(fwd)); 835 fwd.listen_port = lport; 836 if (fwd.listen_port == PORT_STREAMLOCAL) 837 fwd.listen_path = listen_addr; 838 else 839 fwd.listen_host = listen_addr; 840 fwd.connect_port = cport; 841 if (fwd.connect_port == PORT_STREAMLOCAL) 842 fwd.connect_path = connect_addr; 843 else 844 fwd.connect_host = connect_addr; 845 846 debug2("%s: channel %d: request cancel %s", __func__, c->self, 847 (fwd_desc = format_forward(ftype, &fwd))); 848 849 /* make sure this has been requested */ 850 found_fwd = NULL; 851 switch (ftype) { 852 case MUX_FWD_LOCAL: 853 case MUX_FWD_DYNAMIC: 854 for (i = 0; i < options.num_local_forwards; i++) { 855 if (compare_forward(&fwd, 856 options.local_forwards + i)) { 857 found_fwd = options.local_forwards + i; 858 break; 859 } 860 } 861 break; 862 case MUX_FWD_REMOTE: 863 for (i = 0; i < options.num_remote_forwards; i++) { 864 if (compare_forward(&fwd, 865 options.remote_forwards + i)) { 866 found_fwd = options.remote_forwards + i; 867 break; 868 } 869 } 870 break; 871 } 872 873 if (found_fwd == NULL) 874 error_reason = "port not forwarded"; 875 else if (ftype == MUX_FWD_REMOTE) { 876 /* 877 * This shouldn't fail unless we confused the host/port 878 * between options.remote_forwards and permitted_opens. 879 * However, for dynamic allocated listen ports we need 880 * to use the actual listen port. 881 */ 882 if (channel_request_rforward_cancel(found_fwd) == -1) 883 error_reason = "port not in permitted opens"; 884 } else { /* local and dynamic forwards */ 885 /* Ditto */ 886 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 887 &options.fwd_opts) == -1) 888 error_reason = "port not found"; 889 } 890 891 if (error_reason == NULL) { 892 buffer_put_int(r, MUX_S_OK); 893 buffer_put_int(r, rid); 894 895 free(found_fwd->listen_host); 896 free(found_fwd->listen_path); 897 free(found_fwd->connect_host); 898 free(found_fwd->connect_path); 899 found_fwd->listen_host = found_fwd->connect_host = NULL; 900 found_fwd->listen_path = found_fwd->connect_path = NULL; 901 found_fwd->listen_port = found_fwd->connect_port = 0; 902 } else { 903 buffer_put_int(r, MUX_S_FAILURE); 904 buffer_put_int(r, rid); 905 buffer_put_cstring(r, error_reason); 906 } 907 out: 908 free(fwd_desc); 909 free(listen_addr); 910 free(connect_addr); 911 912 return ret; 913 } 914 915 static int 916 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 917 { 918 Channel *nc; 919 char *reserved, *chost; 920 u_int cport, i, j; 921 int new_fd[2]; 922 struct mux_stdio_confirm_ctx *cctx; 923 924 chost = reserved = NULL; 925 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 926 (chost = buffer_get_string_ret(m, NULL)) == NULL || 927 buffer_get_int_ret(&cport, m) != 0) { 928 free(reserved); 929 free(chost); 930 error("%s: malformed message", __func__); 931 return -1; 932 } 933 free(reserved); 934 935 debug2("%s: channel %d: request stdio fwd to %s:%u", 936 __func__, c->self, chost, cport); 937 938 /* Gather fds from client */ 939 for(i = 0; i < 2; i++) { 940 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 941 error("%s: failed to receive fd %d from slave", 942 __func__, i); 943 for (j = 0; j < i; j++) 944 close(new_fd[j]); 945 free(chost); 946 947 /* prepare reply */ 948 buffer_put_int(r, MUX_S_FAILURE); 949 buffer_put_int(r, rid); 950 buffer_put_cstring(r, 951 "did not receive file descriptors"); 952 return -1; 953 } 954 } 955 956 debug3("%s: got fds stdin %d, stdout %d", __func__, 957 new_fd[0], new_fd[1]); 958 959 /* XXX support multiple child sessions in future */ 960 if (c->remote_id != -1) { 961 debug2("%s: session already open", __func__); 962 /* prepare reply */ 963 buffer_put_int(r, MUX_S_FAILURE); 964 buffer_put_int(r, rid); 965 buffer_put_cstring(r, "Multiple sessions not supported"); 966 cleanup: 967 close(new_fd[0]); 968 close(new_fd[1]); 969 free(chost); 970 return 0; 971 } 972 973 if (options.control_master == SSHCTL_MASTER_ASK || 974 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 975 if (!ask_permission("Allow forward to %s:%u? ", 976 chost, cport)) { 977 debug2("%s: stdio fwd refused by user", __func__); 978 /* prepare reply */ 979 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 980 buffer_put_int(r, rid); 981 buffer_put_cstring(r, "Permission denied"); 982 goto cleanup; 983 } 984 } 985 986 /* enable nonblocking unless tty */ 987 if (!isatty(new_fd[0])) 988 set_nonblock(new_fd[0]); 989 if (!isatty(new_fd[1])) 990 set_nonblock(new_fd[1]); 991 992 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 993 994 nc->ctl_chan = c->self; /* link session -> control channel */ 995 c->remote_id = nc->self; /* link control -> session channel */ 996 997 debug2("%s: channel_new: %d linked to control channel %d", 998 __func__, nc->self, nc->ctl_chan); 999 1000 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1001 1002 cctx = xcalloc(1, sizeof(*cctx)); 1003 cctx->rid = rid; 1004 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1005 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1006 1007 /* reply is deferred, sent by mux_session_confirm */ 1008 return 0; 1009 } 1010 1011 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1012 static void 1013 mux_stdio_confirm(int id, int success, void *arg) 1014 { 1015 struct mux_stdio_confirm_ctx *cctx = arg; 1016 Channel *c, *cc; 1017 Buffer reply; 1018 1019 if (cctx == NULL) 1020 fatal("%s: cctx == NULL", __func__); 1021 if ((c = channel_by_id(id)) == NULL) 1022 fatal("%s: no channel for id %d", __func__, id); 1023 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1024 fatal("%s: channel %d lacks control channel %d", __func__, 1025 id, c->ctl_chan); 1026 1027 if (!success) { 1028 debug3("%s: sending failure reply", __func__); 1029 /* prepare reply */ 1030 buffer_init(&reply); 1031 buffer_put_int(&reply, MUX_S_FAILURE); 1032 buffer_put_int(&reply, cctx->rid); 1033 buffer_put_cstring(&reply, "Session open refused by peer"); 1034 goto done; 1035 } 1036 1037 debug3("%s: sending success reply", __func__); 1038 /* prepare reply */ 1039 buffer_init(&reply); 1040 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1041 buffer_put_int(&reply, cctx->rid); 1042 buffer_put_int(&reply, c->self); 1043 1044 done: 1045 /* Send reply */ 1046 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1047 buffer_free(&reply); 1048 1049 if (cc->mux_pause <= 0) 1050 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1051 cc->mux_pause = 0; /* start processing messages again */ 1052 c->open_confirm_ctx = NULL; 1053 free(cctx); 1054 } 1055 1056 static int 1057 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1058 { 1059 debug("%s: channel %d: stop listening", __func__, c->self); 1060 1061 if (options.control_master == SSHCTL_MASTER_ASK || 1062 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1063 if (!ask_permission("Disable further multiplexing on shared " 1064 "connection to %s? ", host)) { 1065 debug2("%s: stop listen refused by user", __func__); 1066 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1067 buffer_put_int(r, rid); 1068 buffer_put_cstring(r, "Permission denied"); 1069 return 0; 1070 } 1071 } 1072 1073 if (mux_listener_channel != NULL) { 1074 channel_free(mux_listener_channel); 1075 client_stop_mux(); 1076 free(options.control_path); 1077 options.control_path = NULL; 1078 mux_listener_channel = NULL; 1079 muxserver_sock = -1; 1080 } 1081 1082 /* prepare reply */ 1083 buffer_put_int(r, MUX_S_OK); 1084 buffer_put_int(r, rid); 1085 1086 return 0; 1087 } 1088 1089 /* Channel callbacks fired on read/write from mux slave fd */ 1090 static int 1091 mux_master_read_cb(Channel *c) 1092 { 1093 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1094 Buffer in, out; 1095 const u_char *ptr; 1096 u_int type, rid, have, i; 1097 int ret = -1; 1098 1099 /* Setup ctx and */ 1100 if (c->mux_ctx == NULL) { 1101 state = xcalloc(1, sizeof(*state)); 1102 c->mux_ctx = state; 1103 channel_register_cleanup(c->self, 1104 mux_master_control_cleanup_cb, 0); 1105 1106 /* Send hello */ 1107 buffer_init(&out); 1108 buffer_put_int(&out, MUX_MSG_HELLO); 1109 buffer_put_int(&out, SSHMUX_VER); 1110 /* no extensions */ 1111 buffer_put_string(&c->output, buffer_ptr(&out), 1112 buffer_len(&out)); 1113 buffer_free(&out); 1114 debug3("%s: channel %d: hello sent", __func__, c->self); 1115 return 0; 1116 } 1117 1118 buffer_init(&in); 1119 buffer_init(&out); 1120 1121 /* Channel code ensures that we receive whole packets */ 1122 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1123 malf: 1124 error("%s: malformed message", __func__); 1125 goto out; 1126 } 1127 buffer_append(&in, ptr, have); 1128 1129 if (buffer_get_int_ret(&type, &in) != 0) 1130 goto malf; 1131 debug3("%s: channel %d packet type 0x%08x len %u", 1132 __func__, c->self, type, buffer_len(&in)); 1133 1134 if (type == MUX_MSG_HELLO) 1135 rid = 0; 1136 else { 1137 if (!state->hello_rcvd) { 1138 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1139 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1140 goto out; 1141 } 1142 if (buffer_get_int_ret(&rid, &in) != 0) 1143 goto malf; 1144 } 1145 1146 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1147 if (type == mux_master_handlers[i].type) { 1148 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1149 break; 1150 } 1151 } 1152 if (mux_master_handlers[i].handler == NULL) { 1153 error("%s: unsupported mux message 0x%08x", __func__, type); 1154 buffer_put_int(&out, MUX_S_FAILURE); 1155 buffer_put_int(&out, rid); 1156 buffer_put_cstring(&out, "unsupported request"); 1157 ret = 0; 1158 } 1159 /* Enqueue reply packet */ 1160 if (buffer_len(&out) != 0) { 1161 buffer_put_string(&c->output, buffer_ptr(&out), 1162 buffer_len(&out)); 1163 } 1164 out: 1165 buffer_free(&in); 1166 buffer_free(&out); 1167 return ret; 1168 } 1169 1170 void 1171 mux_exit_message(Channel *c, int exitval) 1172 { 1173 Buffer m; 1174 Channel *mux_chan; 1175 1176 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1177 exitval); 1178 1179 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1180 fatal("%s: channel %d missing mux channel %d", 1181 __func__, c->self, c->ctl_chan); 1182 1183 /* Append exit message packet to control socket output queue */ 1184 buffer_init(&m); 1185 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1186 buffer_put_int(&m, c->self); 1187 buffer_put_int(&m, exitval); 1188 1189 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1190 buffer_free(&m); 1191 } 1192 1193 void 1194 mux_tty_alloc_failed(Channel *c) 1195 { 1196 Buffer m; 1197 Channel *mux_chan; 1198 1199 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1200 1201 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1202 fatal("%s: channel %d missing mux channel %d", 1203 __func__, c->self, c->ctl_chan); 1204 1205 /* Append exit message packet to control socket output queue */ 1206 buffer_init(&m); 1207 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1208 buffer_put_int(&m, c->self); 1209 1210 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1211 buffer_free(&m); 1212 } 1213 1214 /* Prepare a mux master to listen on a Unix domain socket. */ 1215 void 1216 muxserver_listen(void) 1217 { 1218 mode_t old_umask; 1219 char *orig_control_path = options.control_path; 1220 char rbuf[16+1]; 1221 u_int i, r; 1222 int oerrno; 1223 1224 if (options.control_path == NULL || 1225 options.control_master == SSHCTL_MASTER_NO) 1226 return; 1227 1228 debug("setting up multiplex master socket"); 1229 1230 /* 1231 * Use a temporary path before listen so we can pseudo-atomically 1232 * establish the listening socket in its final location to avoid 1233 * other processes racing in between bind() and listen() and hitting 1234 * an unready socket. 1235 */ 1236 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1237 r = arc4random_uniform(26+26+10); 1238 rbuf[i] = (r < 26) ? 'a' + r : 1239 (r < 26*2) ? 'A' + r - 26 : 1240 '0' + r - 26 - 26; 1241 } 1242 rbuf[sizeof(rbuf) - 1] = '\0'; 1243 options.control_path = NULL; 1244 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1245 debug3("%s: temporary control path %s", __func__, options.control_path); 1246 1247 old_umask = umask(0177); 1248 muxserver_sock = unix_listener(options.control_path, 64, 0); 1249 oerrno = errno; 1250 umask(old_umask); 1251 if (muxserver_sock < 0) { 1252 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1253 error("ControlSocket %s already exists, " 1254 "disabling multiplexing", options.control_path); 1255 disable_mux_master: 1256 if (muxserver_sock != -1) { 1257 close(muxserver_sock); 1258 muxserver_sock = -1; 1259 } 1260 free(orig_control_path); 1261 free(options.control_path); 1262 options.control_path = NULL; 1263 options.control_master = SSHCTL_MASTER_NO; 1264 return; 1265 } else { 1266 /* unix_listener() logs the error */ 1267 cleanup_exit(255); 1268 } 1269 } 1270 1271 /* Now atomically "move" the mux socket into position */ 1272 if (link(options.control_path, orig_control_path) != 0) { 1273 if (errno != EEXIST) { 1274 fatal("%s: link mux listener %s => %s: %s", __func__, 1275 options.control_path, orig_control_path, 1276 strerror(errno)); 1277 } 1278 error("ControlSocket %s already exists, disabling multiplexing", 1279 orig_control_path); 1280 unlink(options.control_path); 1281 goto disable_mux_master; 1282 } 1283 unlink(options.control_path); 1284 free(options.control_path); 1285 options.control_path = orig_control_path; 1286 1287 set_nonblock(muxserver_sock); 1288 1289 mux_listener_channel = channel_new("mux listener", 1290 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1291 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1292 0, options.control_path, 1); 1293 mux_listener_channel->mux_rcb = mux_master_read_cb; 1294 debug3("%s: mux listener channel %d fd %d", __func__, 1295 mux_listener_channel->self, mux_listener_channel->sock); 1296 } 1297 1298 /* Callback on open confirmation in mux master for a mux client session. */ 1299 static void 1300 mux_session_confirm(int id, int success, void *arg) 1301 { 1302 struct mux_session_confirm_ctx *cctx = arg; 1303 const char *display; 1304 Channel *c, *cc; 1305 int i; 1306 Buffer reply; 1307 1308 if (cctx == NULL) 1309 fatal("%s: cctx == NULL", __func__); 1310 if ((c = channel_by_id(id)) == NULL) 1311 fatal("%s: no channel for id %d", __func__, id); 1312 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1313 fatal("%s: channel %d lacks control channel %d", __func__, 1314 id, c->ctl_chan); 1315 1316 if (!success) { 1317 debug3("%s: sending failure reply", __func__); 1318 /* prepare reply */ 1319 buffer_init(&reply); 1320 buffer_put_int(&reply, MUX_S_FAILURE); 1321 buffer_put_int(&reply, cctx->rid); 1322 buffer_put_cstring(&reply, "Session open refused by peer"); 1323 goto done; 1324 } 1325 1326 display = getenv("DISPLAY"); 1327 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1328 char *proto, *data; 1329 1330 /* Get reasonable local authentication information. */ 1331 client_x11_get_proto(display, options.xauth_location, 1332 options.forward_x11_trusted, options.forward_x11_timeout, 1333 &proto, &data); 1334 /* Request forwarding with authentication spoofing. */ 1335 debug("Requesting X11 forwarding with authentication " 1336 "spoofing."); 1337 x11_request_forwarding_with_spoofing(id, display, proto, 1338 data, 1); 1339 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1340 /* XXX exit_on_forward_failure */ 1341 } 1342 1343 if (cctx->want_agent_fwd && options.forward_agent) { 1344 debug("Requesting authentication agent forwarding."); 1345 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1346 packet_send(); 1347 } 1348 1349 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1350 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1351 1352 debug3("%s: sending success reply", __func__); 1353 /* prepare reply */ 1354 buffer_init(&reply); 1355 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1356 buffer_put_int(&reply, cctx->rid); 1357 buffer_put_int(&reply, c->self); 1358 1359 done: 1360 /* Send reply */ 1361 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1362 buffer_free(&reply); 1363 1364 if (cc->mux_pause <= 0) 1365 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1366 cc->mux_pause = 0; /* start processing messages again */ 1367 c->open_confirm_ctx = NULL; 1368 buffer_free(&cctx->cmd); 1369 free(cctx->term); 1370 if (cctx->env != NULL) { 1371 for (i = 0; cctx->env[i] != NULL; i++) 1372 free(cctx->env[i]); 1373 free(cctx->env); 1374 } 1375 free(cctx); 1376 } 1377 1378 /* ** Multiplexing client support */ 1379 1380 /* Exit signal handler */ 1381 static void 1382 control_client_sighandler(int signo) 1383 { 1384 muxclient_terminate = signo; 1385 } 1386 1387 /* 1388 * Relay signal handler - used to pass some signals from mux client to 1389 * mux master. 1390 */ 1391 static void 1392 control_client_sigrelay(int signo) 1393 { 1394 int save_errno = errno; 1395 1396 if (muxserver_pid > 1) 1397 kill(muxserver_pid, signo); 1398 1399 errno = save_errno; 1400 } 1401 1402 static int 1403 mux_client_read(int fd, Buffer *b, u_int need) 1404 { 1405 u_int have; 1406 ssize_t len; 1407 u_char *p; 1408 struct pollfd pfd; 1409 1410 pfd.fd = fd; 1411 pfd.events = POLLIN; 1412 p = buffer_append_space(b, need); 1413 for (have = 0; have < need; ) { 1414 if (muxclient_terminate) { 1415 errno = EINTR; 1416 return -1; 1417 } 1418 len = read(fd, p + have, need - have); 1419 if (len < 0) { 1420 switch (errno) { 1421 case EAGAIN: 1422 (void)poll(&pfd, 1, -1); 1423 /* FALLTHROUGH */ 1424 case EINTR: 1425 continue; 1426 default: 1427 return -1; 1428 } 1429 } 1430 if (len == 0) { 1431 errno = EPIPE; 1432 return -1; 1433 } 1434 have += (u_int)len; 1435 } 1436 return 0; 1437 } 1438 1439 static int 1440 mux_client_write_packet(int fd, Buffer *m) 1441 { 1442 Buffer queue; 1443 u_int have, need; 1444 int oerrno, len; 1445 u_char *ptr; 1446 struct pollfd pfd; 1447 1448 pfd.fd = fd; 1449 pfd.events = POLLOUT; 1450 buffer_init(&queue); 1451 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1452 1453 need = buffer_len(&queue); 1454 ptr = buffer_ptr(&queue); 1455 1456 for (have = 0; have < need; ) { 1457 if (muxclient_terminate) { 1458 buffer_free(&queue); 1459 errno = EINTR; 1460 return -1; 1461 } 1462 len = write(fd, ptr + have, need - have); 1463 if (len < 0) { 1464 switch (errno) { 1465 case EAGAIN: 1466 (void)poll(&pfd, 1, -1); 1467 /* FALLTHROUGH */ 1468 case EINTR: 1469 continue; 1470 default: 1471 oerrno = errno; 1472 buffer_free(&queue); 1473 errno = oerrno; 1474 return -1; 1475 } 1476 } 1477 if (len == 0) { 1478 buffer_free(&queue); 1479 errno = EPIPE; 1480 return -1; 1481 } 1482 have += (u_int)len; 1483 } 1484 buffer_free(&queue); 1485 return 0; 1486 } 1487 1488 static int 1489 mux_client_read_packet(int fd, Buffer *m) 1490 { 1491 Buffer queue; 1492 u_int need, have; 1493 const u_char *ptr; 1494 int oerrno; 1495 1496 buffer_init(&queue); 1497 if (mux_client_read(fd, &queue, 4) != 0) { 1498 if ((oerrno = errno) == EPIPE) 1499 debug3("%s: read header failed: %s", __func__, 1500 strerror(errno)); 1501 buffer_free(&queue); 1502 errno = oerrno; 1503 return -1; 1504 } 1505 need = get_u32(buffer_ptr(&queue)); 1506 if (mux_client_read(fd, &queue, need) != 0) { 1507 oerrno = errno; 1508 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1509 buffer_free(&queue); 1510 errno = oerrno; 1511 return -1; 1512 } 1513 ptr = buffer_get_string_ptr(&queue, &have); 1514 buffer_append(m, ptr, have); 1515 buffer_free(&queue); 1516 return 0; 1517 } 1518 1519 static int 1520 mux_client_hello_exchange(int fd) 1521 { 1522 Buffer m; 1523 u_int type, ver; 1524 1525 buffer_init(&m); 1526 buffer_put_int(&m, MUX_MSG_HELLO); 1527 buffer_put_int(&m, SSHMUX_VER); 1528 /* no extensions */ 1529 1530 if (mux_client_write_packet(fd, &m) != 0) 1531 fatal("%s: write packet: %s", __func__, strerror(errno)); 1532 1533 buffer_clear(&m); 1534 1535 /* Read their HELLO */ 1536 if (mux_client_read_packet(fd, &m) != 0) { 1537 buffer_free(&m); 1538 return -1; 1539 } 1540 1541 type = buffer_get_int(&m); 1542 if (type != MUX_MSG_HELLO) 1543 fatal("%s: expected HELLO (%u) received %u", 1544 __func__, MUX_MSG_HELLO, type); 1545 ver = buffer_get_int(&m); 1546 if (ver != SSHMUX_VER) 1547 fatal("Unsupported multiplexing protocol version %d " 1548 "(expected %d)", ver, SSHMUX_VER); 1549 debug2("%s: master version %u", __func__, ver); 1550 /* No extensions are presently defined */ 1551 while (buffer_len(&m) > 0) { 1552 char *name = buffer_get_string(&m, NULL); 1553 char *value = buffer_get_string(&m, NULL); 1554 1555 debug2("Unrecognised master extension \"%s\"", name); 1556 free(name); 1557 free(value); 1558 } 1559 buffer_free(&m); 1560 return 0; 1561 } 1562 1563 static u_int 1564 mux_client_request_alive(int fd) 1565 { 1566 Buffer m; 1567 char *e; 1568 u_int pid, type, rid; 1569 1570 debug3("%s: entering", __func__); 1571 1572 buffer_init(&m); 1573 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1574 buffer_put_int(&m, muxclient_request_id); 1575 1576 if (mux_client_write_packet(fd, &m) != 0) 1577 fatal("%s: write packet: %s", __func__, strerror(errno)); 1578 1579 buffer_clear(&m); 1580 1581 /* Read their reply */ 1582 if (mux_client_read_packet(fd, &m) != 0) { 1583 buffer_free(&m); 1584 return 0; 1585 } 1586 1587 type = buffer_get_int(&m); 1588 if (type != MUX_S_ALIVE) { 1589 e = buffer_get_string(&m, NULL); 1590 fatal("%s: master returned error: %s", __func__, e); 1591 } 1592 1593 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1594 fatal("%s: out of sequence reply: my id %u theirs %u", 1595 __func__, muxclient_request_id, rid); 1596 pid = buffer_get_int(&m); 1597 buffer_free(&m); 1598 1599 debug3("%s: done pid = %u", __func__, pid); 1600 1601 muxclient_request_id++; 1602 1603 return pid; 1604 } 1605 1606 static void 1607 mux_client_request_terminate(int fd) 1608 { 1609 Buffer m; 1610 char *e; 1611 u_int type, rid; 1612 1613 debug3("%s: entering", __func__); 1614 1615 buffer_init(&m); 1616 buffer_put_int(&m, MUX_C_TERMINATE); 1617 buffer_put_int(&m, muxclient_request_id); 1618 1619 if (mux_client_write_packet(fd, &m) != 0) 1620 fatal("%s: write packet: %s", __func__, strerror(errno)); 1621 1622 buffer_clear(&m); 1623 1624 /* Read their reply */ 1625 if (mux_client_read_packet(fd, &m) != 0) { 1626 /* Remote end exited already */ 1627 if (errno == EPIPE) { 1628 buffer_free(&m); 1629 return; 1630 } 1631 fatal("%s: read from master failed: %s", 1632 __func__, strerror(errno)); 1633 } 1634 1635 type = buffer_get_int(&m); 1636 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1637 fatal("%s: out of sequence reply: my id %u theirs %u", 1638 __func__, muxclient_request_id, rid); 1639 switch (type) { 1640 case MUX_S_OK: 1641 break; 1642 case MUX_S_PERMISSION_DENIED: 1643 e = buffer_get_string(&m, NULL); 1644 fatal("Master refused termination request: %s", e); 1645 case MUX_S_FAILURE: 1646 e = buffer_get_string(&m, NULL); 1647 fatal("%s: termination request failed: %s", __func__, e); 1648 default: 1649 fatal("%s: unexpected response from master 0x%08x", 1650 __func__, type); 1651 } 1652 buffer_free(&m); 1653 muxclient_request_id++; 1654 } 1655 1656 static int 1657 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1658 { 1659 Buffer m; 1660 char *e, *fwd_desc; 1661 u_int type, rid; 1662 1663 fwd_desc = format_forward(ftype, fwd); 1664 debug("Requesting %s %s", 1665 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1666 free(fwd_desc); 1667 1668 buffer_init(&m); 1669 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1670 buffer_put_int(&m, muxclient_request_id); 1671 buffer_put_int(&m, ftype); 1672 if (fwd->listen_path != NULL) { 1673 buffer_put_cstring(&m, fwd->listen_path); 1674 } else { 1675 buffer_put_cstring(&m, 1676 fwd->listen_host == NULL ? "" : fwd->listen_host); 1677 } 1678 buffer_put_int(&m, fwd->listen_port); 1679 if (fwd->connect_path != NULL) { 1680 buffer_put_cstring(&m, fwd->connect_path); 1681 } else { 1682 buffer_put_cstring(&m, 1683 fwd->connect_host == NULL ? "" : fwd->connect_host); 1684 } 1685 buffer_put_int(&m, fwd->connect_port); 1686 1687 if (mux_client_write_packet(fd, &m) != 0) 1688 fatal("%s: write packet: %s", __func__, strerror(errno)); 1689 1690 buffer_clear(&m); 1691 1692 /* Read their reply */ 1693 if (mux_client_read_packet(fd, &m) != 0) { 1694 buffer_free(&m); 1695 return -1; 1696 } 1697 1698 type = buffer_get_int(&m); 1699 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1700 fatal("%s: out of sequence reply: my id %u theirs %u", 1701 __func__, muxclient_request_id, rid); 1702 switch (type) { 1703 case MUX_S_OK: 1704 break; 1705 case MUX_S_REMOTE_PORT: 1706 if (cancel_flag) 1707 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1708 fwd->allocated_port = buffer_get_int(&m); 1709 logit("Allocated port %u for remote forward to %s:%d", 1710 fwd->allocated_port, 1711 fwd->connect_host ? fwd->connect_host : "", 1712 fwd->connect_port); 1713 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1714 fprintf(stdout, "%u\n", fwd->allocated_port); 1715 break; 1716 case MUX_S_PERMISSION_DENIED: 1717 e = buffer_get_string(&m, NULL); 1718 buffer_free(&m); 1719 error("Master refused forwarding request: %s", e); 1720 return -1; 1721 case MUX_S_FAILURE: 1722 e = buffer_get_string(&m, NULL); 1723 buffer_free(&m); 1724 error("%s: forwarding request failed: %s", __func__, e); 1725 return -1; 1726 default: 1727 fatal("%s: unexpected response from master 0x%08x", 1728 __func__, type); 1729 } 1730 buffer_free(&m); 1731 1732 muxclient_request_id++; 1733 return 0; 1734 } 1735 1736 static int 1737 mux_client_forwards(int fd, int cancel_flag) 1738 { 1739 int i, ret = 0; 1740 1741 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1742 cancel_flag ? "cancel" : "request", 1743 options.num_local_forwards, options.num_remote_forwards); 1744 1745 /* XXX ExitOnForwardingFailure */ 1746 for (i = 0; i < options.num_local_forwards; i++) { 1747 if (mux_client_forward(fd, cancel_flag, 1748 options.local_forwards[i].connect_port == 0 ? 1749 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1750 options.local_forwards + i) != 0) 1751 ret = -1; 1752 } 1753 for (i = 0; i < options.num_remote_forwards; i++) { 1754 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1755 options.remote_forwards + i) != 0) 1756 ret = -1; 1757 } 1758 return ret; 1759 } 1760 1761 static int 1762 mux_client_request_session(int fd) 1763 { 1764 Buffer m; 1765 char *e, *term; 1766 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1767 extern char **environ; 1768 int devnull, rawmode; 1769 1770 debug3("%s: entering", __func__); 1771 1772 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1773 error("%s: master alive request failed", __func__); 1774 return -1; 1775 } 1776 1777 signal(SIGPIPE, SIG_IGN); 1778 1779 if (stdin_null_flag) { 1780 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1781 fatal("open(/dev/null): %s", strerror(errno)); 1782 if (dup2(devnull, STDIN_FILENO) == -1) 1783 fatal("dup2: %s", strerror(errno)); 1784 if (devnull > STDERR_FILENO) 1785 close(devnull); 1786 } 1787 1788 term = getenv("TERM"); 1789 1790 buffer_init(&m); 1791 buffer_put_int(&m, MUX_C_NEW_SESSION); 1792 buffer_put_int(&m, muxclient_request_id); 1793 buffer_put_cstring(&m, ""); /* reserved */ 1794 buffer_put_int(&m, tty_flag); 1795 buffer_put_int(&m, options.forward_x11); 1796 buffer_put_int(&m, options.forward_agent); 1797 buffer_put_int(&m, subsystem_flag); 1798 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1799 0xffffffff : (u_int)options.escape_char); 1800 buffer_put_cstring(&m, term == NULL ? "" : term); 1801 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1802 1803 if (options.num_send_env > 0 && environ != NULL) { 1804 /* Pass environment */ 1805 for (i = 0; environ[i] != NULL; i++) { 1806 if (env_permitted(environ[i])) { 1807 buffer_put_cstring(&m, environ[i]); 1808 } 1809 } 1810 } 1811 1812 if (mux_client_write_packet(fd, &m) != 0) 1813 fatal("%s: write packet: %s", __func__, strerror(errno)); 1814 1815 /* Send the stdio file descriptors */ 1816 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1817 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1818 mm_send_fd(fd, STDERR_FILENO) == -1) 1819 fatal("%s: send fds failed", __func__); 1820 1821 debug3("%s: session request sent", __func__); 1822 1823 /* Read their reply */ 1824 buffer_clear(&m); 1825 if (mux_client_read_packet(fd, &m) != 0) { 1826 error("%s: read from master failed: %s", 1827 __func__, strerror(errno)); 1828 buffer_free(&m); 1829 return -1; 1830 } 1831 1832 type = buffer_get_int(&m); 1833 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1834 fatal("%s: out of sequence reply: my id %u theirs %u", 1835 __func__, muxclient_request_id, rid); 1836 switch (type) { 1837 case MUX_S_SESSION_OPENED: 1838 sid = buffer_get_int(&m); 1839 debug("%s: master session id: %u", __func__, sid); 1840 break; 1841 case MUX_S_PERMISSION_DENIED: 1842 e = buffer_get_string(&m, NULL); 1843 buffer_free(&m); 1844 error("Master refused session request: %s", e); 1845 return -1; 1846 case MUX_S_FAILURE: 1847 e = buffer_get_string(&m, NULL); 1848 buffer_free(&m); 1849 error("%s: session request failed: %s", __func__, e); 1850 return -1; 1851 default: 1852 buffer_free(&m); 1853 error("%s: unexpected response from master 0x%08x", 1854 __func__, type); 1855 return -1; 1856 } 1857 muxclient_request_id++; 1858 1859 signal(SIGHUP, control_client_sighandler); 1860 signal(SIGINT, control_client_sighandler); 1861 signal(SIGTERM, control_client_sighandler); 1862 signal(SIGWINCH, control_client_sigrelay); 1863 1864 rawmode = tty_flag; 1865 if (tty_flag) 1866 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1867 1868 /* 1869 * Stick around until the controlee closes the client_fd. 1870 * Before it does, it is expected to write an exit message. 1871 * This process must read the value and wait for the closure of 1872 * the client_fd; if this one closes early, the multiplex master will 1873 * terminate early too (possibly losing data). 1874 */ 1875 for (exitval = 255, exitval_seen = 0;;) { 1876 buffer_clear(&m); 1877 if (mux_client_read_packet(fd, &m) != 0) 1878 break; 1879 type = buffer_get_int(&m); 1880 switch (type) { 1881 case MUX_S_TTY_ALLOC_FAIL: 1882 if ((esid = buffer_get_int(&m)) != sid) 1883 fatal("%s: tty alloc fail on unknown session: " 1884 "my id %u theirs %u", 1885 __func__, sid, esid); 1886 leave_raw_mode(options.request_tty == 1887 REQUEST_TTY_FORCE); 1888 rawmode = 0; 1889 continue; 1890 case MUX_S_EXIT_MESSAGE: 1891 if ((esid = buffer_get_int(&m)) != sid) 1892 fatal("%s: exit on unknown session: " 1893 "my id %u theirs %u", 1894 __func__, sid, esid); 1895 if (exitval_seen) 1896 fatal("%s: exitval sent twice", __func__); 1897 exitval = buffer_get_int(&m); 1898 exitval_seen = 1; 1899 continue; 1900 default: 1901 e = buffer_get_string(&m, NULL); 1902 fatal("%s: master returned error: %s", __func__, e); 1903 } 1904 } 1905 1906 close(fd); 1907 if (rawmode) 1908 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1909 1910 if (muxclient_terminate) { 1911 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1912 exitval = 255; 1913 } else if (!exitval_seen) { 1914 debug2("Control master terminated unexpectedly"); 1915 exitval = 255; 1916 } else 1917 debug2("Received exit status from master %d", exitval); 1918 1919 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1920 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1921 1922 exit(exitval); 1923 } 1924 1925 static int 1926 mux_client_request_stdio_fwd(int fd) 1927 { 1928 Buffer m; 1929 char *e; 1930 u_int type, rid, sid; 1931 int devnull; 1932 1933 debug3("%s: entering", __func__); 1934 1935 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1936 error("%s: master alive request failed", __func__); 1937 return -1; 1938 } 1939 1940 signal(SIGPIPE, SIG_IGN); 1941 1942 if (stdin_null_flag) { 1943 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1944 fatal("open(/dev/null): %s", strerror(errno)); 1945 if (dup2(devnull, STDIN_FILENO) == -1) 1946 fatal("dup2: %s", strerror(errno)); 1947 if (devnull > STDERR_FILENO) 1948 close(devnull); 1949 } 1950 1951 buffer_init(&m); 1952 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1953 buffer_put_int(&m, muxclient_request_id); 1954 buffer_put_cstring(&m, ""); /* reserved */ 1955 buffer_put_cstring(&m, stdio_forward_host); 1956 buffer_put_int(&m, stdio_forward_port); 1957 1958 if (mux_client_write_packet(fd, &m) != 0) 1959 fatal("%s: write packet: %s", __func__, strerror(errno)); 1960 1961 /* Send the stdio file descriptors */ 1962 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1963 mm_send_fd(fd, STDOUT_FILENO) == -1) 1964 fatal("%s: send fds failed", __func__); 1965 1966 debug3("%s: stdio forward request sent", __func__); 1967 1968 /* Read their reply */ 1969 buffer_clear(&m); 1970 1971 if (mux_client_read_packet(fd, &m) != 0) { 1972 error("%s: read from master failed: %s", 1973 __func__, strerror(errno)); 1974 buffer_free(&m); 1975 return -1; 1976 } 1977 1978 type = buffer_get_int(&m); 1979 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1980 fatal("%s: out of sequence reply: my id %u theirs %u", 1981 __func__, muxclient_request_id, rid); 1982 switch (type) { 1983 case MUX_S_SESSION_OPENED: 1984 sid = buffer_get_int(&m); 1985 debug("%s: master session id: %u", __func__, sid); 1986 break; 1987 case MUX_S_PERMISSION_DENIED: 1988 e = buffer_get_string(&m, NULL); 1989 buffer_free(&m); 1990 fatal("Master refused stdio forwarding request: %s", e); 1991 case MUX_S_FAILURE: 1992 e = buffer_get_string(&m, NULL); 1993 buffer_free(&m); 1994 fatal("Stdio forwarding request failed: %s", e); 1995 default: 1996 buffer_free(&m); 1997 error("%s: unexpected response from master 0x%08x", 1998 __func__, type); 1999 return -1; 2000 } 2001 muxclient_request_id++; 2002 2003 signal(SIGHUP, control_client_sighandler); 2004 signal(SIGINT, control_client_sighandler); 2005 signal(SIGTERM, control_client_sighandler); 2006 signal(SIGWINCH, control_client_sigrelay); 2007 2008 /* 2009 * Stick around until the controlee closes the client_fd. 2010 */ 2011 buffer_clear(&m); 2012 if (mux_client_read_packet(fd, &m) != 0) { 2013 if (errno == EPIPE || 2014 (errno == EINTR && muxclient_terminate != 0)) 2015 return 0; 2016 fatal("%s: mux_client_read_packet: %s", 2017 __func__, strerror(errno)); 2018 } 2019 fatal("%s: master returned unexpected message %u", __func__, type); 2020 } 2021 2022 static void 2023 mux_client_request_stop_listening(int fd) 2024 { 2025 Buffer m; 2026 char *e; 2027 u_int type, rid; 2028 2029 debug3("%s: entering", __func__); 2030 2031 buffer_init(&m); 2032 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2033 buffer_put_int(&m, muxclient_request_id); 2034 2035 if (mux_client_write_packet(fd, &m) != 0) 2036 fatal("%s: write packet: %s", __func__, strerror(errno)); 2037 2038 buffer_clear(&m); 2039 2040 /* Read their reply */ 2041 if (mux_client_read_packet(fd, &m) != 0) 2042 fatal("%s: read from master failed: %s", 2043 __func__, strerror(errno)); 2044 2045 type = buffer_get_int(&m); 2046 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2047 fatal("%s: out of sequence reply: my id %u theirs %u", 2048 __func__, muxclient_request_id, rid); 2049 switch (type) { 2050 case MUX_S_OK: 2051 break; 2052 case MUX_S_PERMISSION_DENIED: 2053 e = buffer_get_string(&m, NULL); 2054 fatal("Master refused stop listening request: %s", e); 2055 case MUX_S_FAILURE: 2056 e = buffer_get_string(&m, NULL); 2057 fatal("%s: stop listening request failed: %s", __func__, e); 2058 default: 2059 fatal("%s: unexpected response from master 0x%08x", 2060 __func__, type); 2061 } 2062 buffer_free(&m); 2063 muxclient_request_id++; 2064 } 2065 2066 /* Multiplex client main loop. */ 2067 void 2068 muxclient(const char *path) 2069 { 2070 struct sockaddr_un addr; 2071 int sock; 2072 u_int pid; 2073 2074 if (muxclient_command == 0) { 2075 if (stdio_forward_host != NULL) 2076 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2077 else 2078 muxclient_command = SSHMUX_COMMAND_OPEN; 2079 } 2080 2081 switch (options.control_master) { 2082 case SSHCTL_MASTER_AUTO: 2083 case SSHCTL_MASTER_AUTO_ASK: 2084 debug("auto-mux: Trying existing master"); 2085 /* FALLTHROUGH */ 2086 case SSHCTL_MASTER_NO: 2087 break; 2088 default: 2089 return; 2090 } 2091 2092 memset(&addr, '\0', sizeof(addr)); 2093 addr.sun_family = AF_UNIX; 2094 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 2095 strlen(path) + 1; 2096 2097 if (strlcpy(addr.sun_path, path, 2098 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2099 fatal("ControlPath too long"); 2100 2101 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2102 fatal("%s socket(): %s", __func__, strerror(errno)); 2103 2104 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 2105 switch (muxclient_command) { 2106 case SSHMUX_COMMAND_OPEN: 2107 case SSHMUX_COMMAND_STDIO_FWD: 2108 break; 2109 default: 2110 fatal("Control socket connect(%.100s): %s", path, 2111 strerror(errno)); 2112 } 2113 if (errno == ECONNREFUSED && 2114 options.control_master != SSHCTL_MASTER_NO) { 2115 debug("Stale control socket %.100s, unlinking", path); 2116 unlink(path); 2117 } else if (errno == ENOENT) { 2118 debug("Control socket \"%.100s\" does not exist", path); 2119 } else { 2120 error("Control socket connect(%.100s): %s", path, 2121 strerror(errno)); 2122 } 2123 close(sock); 2124 return; 2125 } 2126 set_nonblock(sock); 2127 2128 if (mux_client_hello_exchange(sock) != 0) { 2129 error("%s: master hello exchange failed", __func__); 2130 close(sock); 2131 return; 2132 } 2133 2134 switch (muxclient_command) { 2135 case SSHMUX_COMMAND_ALIVE_CHECK: 2136 if ((pid = mux_client_request_alive(sock)) == 0) 2137 fatal("%s: master alive check failed", __func__); 2138 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2139 exit(0); 2140 case SSHMUX_COMMAND_TERMINATE: 2141 mux_client_request_terminate(sock); 2142 fprintf(stderr, "Exit request sent.\r\n"); 2143 exit(0); 2144 case SSHMUX_COMMAND_FORWARD: 2145 if (mux_client_forwards(sock, 0) != 0) 2146 fatal("%s: master forward request failed", __func__); 2147 exit(0); 2148 case SSHMUX_COMMAND_OPEN: 2149 if (mux_client_forwards(sock, 0) != 0) { 2150 error("%s: master forward request failed", __func__); 2151 return; 2152 } 2153 mux_client_request_session(sock); 2154 return; 2155 case SSHMUX_COMMAND_STDIO_FWD: 2156 mux_client_request_stdio_fwd(sock); 2157 exit(0); 2158 case SSHMUX_COMMAND_STOP: 2159 mux_client_request_stop_listening(sock); 2160 fprintf(stderr, "Stop listening request sent.\r\n"); 2161 exit(0); 2162 case SSHMUX_COMMAND_CANCEL_FWD: 2163 if (mux_client_forwards(sock, 1) != 0) 2164 error("%s: master cancel forward request failed", 2165 __func__); 2166 exit(0); 2167 default: 2168 fatal("unrecognised muxclient_command %d", muxclient_command); 2169 } 2170 } 2171