1 /* $OpenBSD: mux.c,v 1.50 2015/01/20 23:14:00 deraadt Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm (at) openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 /* 21 * TODO: 22 * - Better signalling from master to slave, especially passing of 23 * error messages 24 * - Better fall-back from mux slave error to new connection. 25 * - ExitOnForwardingFailure 26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 27 * - Support ~^Z in mux slaves. 28 * - Inspect or control sessions in master. 29 * - If we ever support the "signal" channel request, send signals on 30 * sessions in master. 31 */ 32 33 #include "includes.h" 34 35 #include <sys/types.h> 36 #include <sys/stat.h> 37 #include <sys/socket.h> 38 #include <sys/un.h> 39 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <signal.h> 43 #include <stdarg.h> 44 #include <stddef.h> 45 #include <stdlib.h> 46 #include <stdio.h> 47 #include <string.h> 48 #include <unistd.h> 49 #ifdef HAVE_PATHS_H 50 #include <paths.h> 51 #endif 52 53 #ifdef HAVE_POLL_H 54 #include <poll.h> 55 #else 56 # ifdef HAVE_SYS_POLL_H 57 # include <sys/poll.h> 58 # endif 59 #endif 60 61 #ifdef HAVE_UTIL_H 62 # include <util.h> 63 #endif 64 65 #include "openbsd-compat/sys-queue.h" 66 #include "xmalloc.h" 67 #include "log.h" 68 #include "ssh.h" 69 #include "ssh2.h" 70 #include "pathnames.h" 71 #include "misc.h" 72 #include "match.h" 73 #include "buffer.h" 74 #include "channels.h" 75 #include "msg.h" 76 #include "packet.h" 77 #include "monitor_fdpass.h" 78 #include "sshpty.h" 79 #include "key.h" 80 #include "readconf.h" 81 #include "clientloop.h" 82 83 /* from ssh.c */ 84 extern int tty_flag; 85 extern Options options; 86 extern int stdin_null_flag; 87 extern char *host; 88 extern int subsystem_flag; 89 extern Buffer command; 90 extern volatile sig_atomic_t quit_pending; 91 extern char *stdio_forward_host; 92 extern int stdio_forward_port; 93 94 /* Context for session open confirmation callback */ 95 struct mux_session_confirm_ctx { 96 u_int want_tty; 97 u_int want_subsys; 98 u_int want_x_fwd; 99 u_int want_agent_fwd; 100 Buffer cmd; 101 char *term; 102 struct termios tio; 103 char **env; 104 u_int rid; 105 }; 106 107 /* Context for stdio fwd open confirmation callback */ 108 struct mux_stdio_confirm_ctx { 109 u_int rid; 110 }; 111 112 /* Context for global channel callback */ 113 struct mux_channel_confirm_ctx { 114 u_int cid; /* channel id */ 115 u_int rid; /* request id */ 116 int fid; /* forward id */ 117 }; 118 119 /* fd to control socket */ 120 int muxserver_sock = -1; 121 122 /* client request id */ 123 u_int muxclient_request_id = 0; 124 125 /* Multiplexing control command */ 126 u_int muxclient_command = 0; 127 128 /* Set when signalled. */ 129 static volatile sig_atomic_t muxclient_terminate = 0; 130 131 /* PID of multiplex server */ 132 static u_int muxserver_pid = 0; 133 134 static Channel *mux_listener_channel = NULL; 135 136 struct mux_master_state { 137 int hello_rcvd; 138 }; 139 140 /* mux protocol messages */ 141 #define MUX_MSG_HELLO 0x00000001 142 #define MUX_C_NEW_SESSION 0x10000002 143 #define MUX_C_ALIVE_CHECK 0x10000004 144 #define MUX_C_TERMINATE 0x10000005 145 #define MUX_C_OPEN_FWD 0x10000006 146 #define MUX_C_CLOSE_FWD 0x10000007 147 #define MUX_C_NEW_STDIO_FWD 0x10000008 148 #define MUX_C_STOP_LISTENING 0x10000009 149 #define MUX_S_OK 0x80000001 150 #define MUX_S_PERMISSION_DENIED 0x80000002 151 #define MUX_S_FAILURE 0x80000003 152 #define MUX_S_EXIT_MESSAGE 0x80000004 153 #define MUX_S_ALIVE 0x80000005 154 #define MUX_S_SESSION_OPENED 0x80000006 155 #define MUX_S_REMOTE_PORT 0x80000007 156 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 157 158 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 159 #define MUX_FWD_LOCAL 1 160 #define MUX_FWD_REMOTE 2 161 #define MUX_FWD_DYNAMIC 3 162 163 static void mux_session_confirm(int, int, void *); 164 static void mux_stdio_confirm(int, int, void *); 165 166 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 167 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 168 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 169 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 170 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 171 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 172 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 173 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 174 175 static const struct { 176 u_int type; 177 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 178 } mux_master_handlers[] = { 179 { MUX_MSG_HELLO, process_mux_master_hello }, 180 { MUX_C_NEW_SESSION, process_mux_new_session }, 181 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 182 { MUX_C_TERMINATE, process_mux_terminate }, 183 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 184 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 185 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 186 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 187 { 0, NULL } 188 }; 189 190 /* Cleanup callback fired on closure of mux slave _session_ channel */ 191 /* ARGSUSED */ 192 static void 193 mux_master_session_cleanup_cb(int cid, void *unused) 194 { 195 Channel *cc, *c = channel_by_id(cid); 196 197 debug3("%s: entering for channel %d", __func__, cid); 198 if (c == NULL) 199 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 200 if (c->ctl_chan != -1) { 201 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 202 fatal("%s: channel %d missing control channel %d", 203 __func__, c->self, c->ctl_chan); 204 c->ctl_chan = -1; 205 cc->remote_id = -1; 206 chan_rcvd_oclose(cc); 207 } 208 channel_cancel_cleanup(c->self); 209 } 210 211 /* Cleanup callback fired on closure of mux slave _control_ channel */ 212 /* ARGSUSED */ 213 static void 214 mux_master_control_cleanup_cb(int cid, void *unused) 215 { 216 Channel *sc, *c = channel_by_id(cid); 217 218 debug3("%s: entering for channel %d", __func__, cid); 219 if (c == NULL) 220 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 221 if (c->remote_id != -1) { 222 if ((sc = channel_by_id(c->remote_id)) == NULL) 223 fatal("%s: channel %d missing session channel %d", 224 __func__, c->self, c->remote_id); 225 c->remote_id = -1; 226 sc->ctl_chan = -1; 227 if (sc->type != SSH_CHANNEL_OPEN && 228 sc->type != SSH_CHANNEL_OPENING) { 229 debug2("%s: channel %d: not open", __func__, sc->self); 230 chan_mark_dead(sc); 231 } else { 232 if (sc->istate == CHAN_INPUT_OPEN) 233 chan_read_failed(sc); 234 if (sc->ostate == CHAN_OUTPUT_OPEN) 235 chan_write_failed(sc); 236 } 237 } 238 channel_cancel_cleanup(c->self); 239 } 240 241 /* Check mux client environment variables before passing them to mux master. */ 242 static int 243 env_permitted(char *env) 244 { 245 int i, ret; 246 char name[1024], *cp; 247 248 if ((cp = strchr(env, '=')) == NULL || cp == env) 249 return 0; 250 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 251 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 252 error("env_permitted: name '%.100s...' too long", env); 253 return 0; 254 } 255 256 for (i = 0; i < options.num_send_env; i++) 257 if (match_pattern(name, options.send_env[i])) 258 return 1; 259 260 return 0; 261 } 262 263 /* Mux master protocol message handlers */ 264 265 static int 266 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 267 { 268 u_int ver; 269 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 270 271 if (state == NULL) 272 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 273 if (state->hello_rcvd) { 274 error("%s: HELLO received twice", __func__); 275 return -1; 276 } 277 if (buffer_get_int_ret(&ver, m) != 0) { 278 malf: 279 error("%s: malformed message", __func__); 280 return -1; 281 } 282 if (ver != SSHMUX_VER) { 283 error("Unsupported multiplexing protocol version %d " 284 "(expected %d)", ver, SSHMUX_VER); 285 return -1; 286 } 287 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 288 289 /* No extensions are presently defined */ 290 while (buffer_len(m) > 0) { 291 char *name = buffer_get_string_ret(m, NULL); 292 char *value = buffer_get_string_ret(m, NULL); 293 294 if (name == NULL || value == NULL) { 295 free(name); 296 free(value); 297 goto malf; 298 } 299 debug2("Unrecognised slave extension \"%s\"", name); 300 free(name); 301 free(value); 302 } 303 state->hello_rcvd = 1; 304 return 0; 305 } 306 307 static int 308 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 309 { 310 Channel *nc; 311 struct mux_session_confirm_ctx *cctx; 312 char *reserved, *cmd, *cp; 313 u_int i, j, len, env_len, escape_char, window, packetmax; 314 int new_fd[3]; 315 316 /* Reply for SSHMUX_COMMAND_OPEN */ 317 cctx = xcalloc(1, sizeof(*cctx)); 318 cctx->term = NULL; 319 cctx->rid = rid; 320 cmd = reserved = NULL; 321 cctx->env = NULL; 322 env_len = 0; 323 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 324 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 325 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 326 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 327 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 328 buffer_get_int_ret(&escape_char, m) != 0 || 329 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 330 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 331 malf: 332 free(cmd); 333 free(reserved); 334 for (j = 0; j < env_len; j++) 335 free(cctx->env[j]); 336 free(cctx->env); 337 free(cctx->term); 338 free(cctx); 339 error("%s: malformed message", __func__); 340 return -1; 341 } 342 free(reserved); 343 reserved = NULL; 344 345 while (buffer_len(m) > 0) { 346 #define MUX_MAX_ENV_VARS 4096 347 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 348 goto malf; 349 if (!env_permitted(cp)) { 350 free(cp); 351 continue; 352 } 353 cctx->env = xrealloc(cctx->env, env_len + 2, 354 sizeof(*cctx->env)); 355 cctx->env[env_len++] = cp; 356 cctx->env[env_len] = NULL; 357 if (env_len > MUX_MAX_ENV_VARS) { 358 error(">%d environment variables received, ignoring " 359 "additional", MUX_MAX_ENV_VARS); 360 break; 361 } 362 } 363 364 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 365 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 366 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 367 cctx->want_subsys, cctx->term, cmd, env_len); 368 369 buffer_init(&cctx->cmd); 370 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 371 free(cmd); 372 cmd = NULL; 373 374 /* Gather fds from client */ 375 for(i = 0; i < 3; i++) { 376 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 377 error("%s: failed to receive fd %d from slave", 378 __func__, i); 379 for (j = 0; j < i; j++) 380 close(new_fd[j]); 381 for (j = 0; j < env_len; j++) 382 free(cctx->env[j]); 383 free(cctx->env); 384 free(cctx->term); 385 buffer_free(&cctx->cmd); 386 free(cctx); 387 388 /* prepare reply */ 389 buffer_put_int(r, MUX_S_FAILURE); 390 buffer_put_int(r, rid); 391 buffer_put_cstring(r, 392 "did not receive file descriptors"); 393 return -1; 394 } 395 } 396 397 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 398 new_fd[0], new_fd[1], new_fd[2]); 399 400 /* XXX support multiple child sessions in future */ 401 if (c->remote_id != -1) { 402 debug2("%s: session already open", __func__); 403 /* prepare reply */ 404 buffer_put_int(r, MUX_S_FAILURE); 405 buffer_put_int(r, rid); 406 buffer_put_cstring(r, "Multiple sessions not supported"); 407 cleanup: 408 close(new_fd[0]); 409 close(new_fd[1]); 410 close(new_fd[2]); 411 free(cctx->term); 412 if (env_len != 0) { 413 for (i = 0; i < env_len; i++) 414 free(cctx->env[i]); 415 free(cctx->env); 416 } 417 buffer_free(&cctx->cmd); 418 free(cctx); 419 return 0; 420 } 421 422 if (options.control_master == SSHCTL_MASTER_ASK || 423 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 424 if (!ask_permission("Allow shared connection to %s? ", host)) { 425 debug2("%s: session refused by user", __func__); 426 /* prepare reply */ 427 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 428 buffer_put_int(r, rid); 429 buffer_put_cstring(r, "Permission denied"); 430 goto cleanup; 431 } 432 } 433 434 /* Try to pick up ttymodes from client before it goes raw */ 435 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 436 error("%s: tcgetattr: %s", __func__, strerror(errno)); 437 438 /* enable nonblocking unless tty */ 439 if (!isatty(new_fd[0])) 440 set_nonblock(new_fd[0]); 441 if (!isatty(new_fd[1])) 442 set_nonblock(new_fd[1]); 443 if (!isatty(new_fd[2])) 444 set_nonblock(new_fd[2]); 445 446 window = CHAN_SES_WINDOW_DEFAULT; 447 packetmax = CHAN_SES_PACKET_DEFAULT; 448 if (cctx->want_tty) { 449 window >>= 1; 450 packetmax >>= 1; 451 } 452 453 nc = channel_new("session", SSH_CHANNEL_OPENING, 454 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 455 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 456 457 nc->ctl_chan = c->self; /* link session -> control channel */ 458 c->remote_id = nc->self; /* link control -> session channel */ 459 460 if (cctx->want_tty && escape_char != 0xffffffff) { 461 channel_register_filter(nc->self, 462 client_simple_escape_filter, NULL, 463 client_filter_cleanup, 464 client_new_escape_filter_ctx((int)escape_char)); 465 } 466 467 debug2("%s: channel_new: %d linked to control channel %d", 468 __func__, nc->self, nc->ctl_chan); 469 470 channel_send_open(nc->self); 471 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 472 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 473 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 474 475 /* reply is deferred, sent by mux_session_confirm */ 476 return 0; 477 } 478 479 static int 480 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 481 { 482 debug2("%s: channel %d: alive check", __func__, c->self); 483 484 /* prepare reply */ 485 buffer_put_int(r, MUX_S_ALIVE); 486 buffer_put_int(r, rid); 487 buffer_put_int(r, (u_int)getpid()); 488 489 return 0; 490 } 491 492 static int 493 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 494 { 495 debug2("%s: channel %d: terminate request", __func__, c->self); 496 497 if (options.control_master == SSHCTL_MASTER_ASK || 498 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 499 if (!ask_permission("Terminate shared connection to %s? ", 500 host)) { 501 debug2("%s: termination refused by user", __func__); 502 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 503 buffer_put_int(r, rid); 504 buffer_put_cstring(r, "Permission denied"); 505 return 0; 506 } 507 } 508 509 quit_pending = 1; 510 buffer_put_int(r, MUX_S_OK); 511 buffer_put_int(r, rid); 512 /* XXX exit happens too soon - message never makes it to client */ 513 return 0; 514 } 515 516 static char * 517 format_forward(u_int ftype, struct Forward *fwd) 518 { 519 char *ret; 520 521 switch (ftype) { 522 case MUX_FWD_LOCAL: 523 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 524 (fwd->listen_path != NULL) ? fwd->listen_path : 525 (fwd->listen_host == NULL) ? 526 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 527 fwd->listen_host, fwd->listen_port, 528 (fwd->connect_path != NULL) ? fwd->connect_path : 529 fwd->connect_host, fwd->connect_port); 530 break; 531 case MUX_FWD_DYNAMIC: 532 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 533 (fwd->listen_host == NULL) ? 534 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 535 fwd->listen_host, fwd->listen_port); 536 break; 537 case MUX_FWD_REMOTE: 538 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 539 (fwd->listen_path != NULL) ? fwd->listen_path : 540 (fwd->listen_host == NULL) ? 541 "LOCALHOST" : fwd->listen_host, 542 fwd->listen_port, 543 (fwd->connect_path != NULL) ? fwd->connect_path : 544 fwd->connect_host, fwd->connect_port); 545 break; 546 default: 547 fatal("%s: unknown forward type %u", __func__, ftype); 548 } 549 return ret; 550 } 551 552 static int 553 compare_host(const char *a, const char *b) 554 { 555 if (a == NULL && b == NULL) 556 return 1; 557 if (a == NULL || b == NULL) 558 return 0; 559 return strcmp(a, b) == 0; 560 } 561 562 static int 563 compare_forward(struct Forward *a, struct Forward *b) 564 { 565 if (!compare_host(a->listen_host, b->listen_host)) 566 return 0; 567 if (!compare_host(a->listen_path, b->listen_path)) 568 return 0; 569 if (a->listen_port != b->listen_port) 570 return 0; 571 if (!compare_host(a->connect_host, b->connect_host)) 572 return 0; 573 if (!compare_host(a->connect_path, b->connect_path)) 574 return 0; 575 if (a->connect_port != b->connect_port) 576 return 0; 577 578 return 1; 579 } 580 581 static void 582 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 583 { 584 struct mux_channel_confirm_ctx *fctx = ctxt; 585 char *failmsg = NULL; 586 struct Forward *rfwd; 587 Channel *c; 588 Buffer out; 589 590 if ((c = channel_by_id(fctx->cid)) == NULL) { 591 /* no channel for reply */ 592 error("%s: unknown channel", __func__); 593 return; 594 } 595 buffer_init(&out); 596 if (fctx->fid >= options.num_remote_forwards) { 597 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 598 goto fail; 599 } 600 rfwd = &options.remote_forwards[fctx->fid]; 601 debug("%s: %s for: listen %d, connect %s:%d", __func__, 602 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 603 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 604 rfwd->connect_host, rfwd->connect_port); 605 if (type == SSH2_MSG_REQUEST_SUCCESS) { 606 if (rfwd->listen_port == 0) { 607 rfwd->allocated_port = packet_get_int(); 608 logit("Allocated port %u for mux remote forward" 609 " to %s:%d", rfwd->allocated_port, 610 rfwd->connect_host, rfwd->connect_port); 611 buffer_put_int(&out, MUX_S_REMOTE_PORT); 612 buffer_put_int(&out, fctx->rid); 613 buffer_put_int(&out, rfwd->allocated_port); 614 channel_update_permitted_opens(rfwd->handle, 615 rfwd->allocated_port); 616 } else { 617 buffer_put_int(&out, MUX_S_OK); 618 buffer_put_int(&out, fctx->rid); 619 } 620 goto out; 621 } else { 622 if (rfwd->listen_port == 0) 623 channel_update_permitted_opens(rfwd->handle, -1); 624 if (rfwd->listen_path != NULL) 625 xasprintf(&failmsg, "remote port forwarding failed for " 626 "listen path %s", rfwd->listen_path); 627 else 628 xasprintf(&failmsg, "remote port forwarding failed for " 629 "listen port %d", rfwd->listen_port); 630 } 631 fail: 632 error("%s: %s", __func__, failmsg); 633 buffer_put_int(&out, MUX_S_FAILURE); 634 buffer_put_int(&out, fctx->rid); 635 buffer_put_cstring(&out, failmsg); 636 free(failmsg); 637 out: 638 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 639 buffer_free(&out); 640 if (c->mux_pause <= 0) 641 fatal("%s: mux_pause %d", __func__, c->mux_pause); 642 c->mux_pause = 0; /* start processing messages again */ 643 } 644 645 static int 646 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 647 { 648 struct Forward fwd; 649 char *fwd_desc = NULL; 650 char *listen_addr, *connect_addr; 651 u_int ftype; 652 u_int lport, cport; 653 int i, ret = 0, freefwd = 1; 654 655 /* XXX - lport/cport check redundant */ 656 if (buffer_get_int_ret(&ftype, m) != 0 || 657 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 658 buffer_get_int_ret(&lport, m) != 0 || 659 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 660 buffer_get_int_ret(&cport, m) != 0 || 661 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 662 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 663 error("%s: malformed message", __func__); 664 ret = -1; 665 goto out; 666 } 667 if (*listen_addr == '\0') { 668 free(listen_addr); 669 listen_addr = NULL; 670 } 671 if (*connect_addr == '\0') { 672 free(connect_addr); 673 connect_addr = NULL; 674 } 675 676 memset(&fwd, 0, sizeof(fwd)); 677 fwd.listen_port = lport; 678 if (fwd.listen_port == PORT_STREAMLOCAL) 679 fwd.listen_path = listen_addr; 680 else 681 fwd.listen_host = listen_addr; 682 fwd.connect_port = cport; 683 if (fwd.connect_port == PORT_STREAMLOCAL) 684 fwd.connect_path = connect_addr; 685 else 686 fwd.connect_host = connect_addr; 687 688 debug2("%s: channel %d: request %s", __func__, c->self, 689 (fwd_desc = format_forward(ftype, &fwd))); 690 691 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 692 ftype != MUX_FWD_DYNAMIC) { 693 logit("%s: invalid forwarding type %u", __func__, ftype); 694 invalid: 695 free(listen_addr); 696 free(connect_addr); 697 buffer_put_int(r, MUX_S_FAILURE); 698 buffer_put_int(r, rid); 699 buffer_put_cstring(r, "Invalid forwarding request"); 700 return 0; 701 } 702 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 703 logit("%s: streamlocal and dynamic forwards " 704 "are mutually exclusive", __func__); 705 goto invalid; 706 } 707 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 708 logit("%s: invalid listen port %u", __func__, 709 fwd.listen_port); 710 goto invalid; 711 } 712 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 713 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 714 logit("%s: invalid connect port %u", __func__, 715 fwd.connect_port); 716 goto invalid; 717 } 718 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 719 logit("%s: missing connect host", __func__); 720 goto invalid; 721 } 722 723 /* Skip forwards that have already been requested */ 724 switch (ftype) { 725 case MUX_FWD_LOCAL: 726 case MUX_FWD_DYNAMIC: 727 for (i = 0; i < options.num_local_forwards; i++) { 728 if (compare_forward(&fwd, 729 options.local_forwards + i)) { 730 exists: 731 debug2("%s: found existing forwarding", 732 __func__); 733 buffer_put_int(r, MUX_S_OK); 734 buffer_put_int(r, rid); 735 goto out; 736 } 737 } 738 break; 739 case MUX_FWD_REMOTE: 740 for (i = 0; i < options.num_remote_forwards; i++) { 741 if (compare_forward(&fwd, 742 options.remote_forwards + i)) { 743 if (fwd.listen_port != 0) 744 goto exists; 745 debug2("%s: found allocated port", 746 __func__); 747 buffer_put_int(r, MUX_S_REMOTE_PORT); 748 buffer_put_int(r, rid); 749 buffer_put_int(r, 750 options.remote_forwards[i].allocated_port); 751 goto out; 752 } 753 } 754 break; 755 } 756 757 if (options.control_master == SSHCTL_MASTER_ASK || 758 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 759 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 760 debug2("%s: forwarding refused by user", __func__); 761 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 762 buffer_put_int(r, rid); 763 buffer_put_cstring(r, "Permission denied"); 764 goto out; 765 } 766 } 767 768 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 769 if (!channel_setup_local_fwd_listener(&fwd, 770 &options.fwd_opts)) { 771 fail: 772 logit("slave-requested %s failed", fwd_desc); 773 buffer_put_int(r, MUX_S_FAILURE); 774 buffer_put_int(r, rid); 775 buffer_put_cstring(r, "Port forwarding failed"); 776 goto out; 777 } 778 add_local_forward(&options, &fwd); 779 freefwd = 0; 780 } else { 781 struct mux_channel_confirm_ctx *fctx; 782 783 fwd.handle = channel_request_remote_forwarding(&fwd); 784 if (fwd.handle < 0) 785 goto fail; 786 add_remote_forward(&options, &fwd); 787 fctx = xcalloc(1, sizeof(*fctx)); 788 fctx->cid = c->self; 789 fctx->rid = rid; 790 fctx->fid = options.num_remote_forwards - 1; 791 client_register_global_confirm(mux_confirm_remote_forward, 792 fctx); 793 freefwd = 0; 794 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 795 /* delayed reply in mux_confirm_remote_forward */ 796 goto out; 797 } 798 buffer_put_int(r, MUX_S_OK); 799 buffer_put_int(r, rid); 800 out: 801 free(fwd_desc); 802 if (freefwd) { 803 free(fwd.listen_host); 804 free(fwd.listen_path); 805 free(fwd.connect_host); 806 free(fwd.connect_path); 807 } 808 return ret; 809 } 810 811 static int 812 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 813 { 814 struct Forward fwd, *found_fwd; 815 char *fwd_desc = NULL; 816 const char *error_reason = NULL; 817 char *listen_addr = NULL, *connect_addr = NULL; 818 u_int ftype; 819 int i, ret = 0; 820 u_int lport, cport; 821 822 if (buffer_get_int_ret(&ftype, m) != 0 || 823 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 824 buffer_get_int_ret(&lport, m) != 0 || 825 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 826 buffer_get_int_ret(&cport, m) != 0 || 827 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 828 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 829 error("%s: malformed message", __func__); 830 ret = -1; 831 goto out; 832 } 833 834 if (*listen_addr == '\0') { 835 free(listen_addr); 836 listen_addr = NULL; 837 } 838 if (*connect_addr == '\0') { 839 free(connect_addr); 840 connect_addr = NULL; 841 } 842 843 memset(&fwd, 0, sizeof(fwd)); 844 fwd.listen_port = lport; 845 if (fwd.listen_port == PORT_STREAMLOCAL) 846 fwd.listen_path = listen_addr; 847 else 848 fwd.listen_host = listen_addr; 849 fwd.connect_port = cport; 850 if (fwd.connect_port == PORT_STREAMLOCAL) 851 fwd.connect_path = connect_addr; 852 else 853 fwd.connect_host = connect_addr; 854 855 debug2("%s: channel %d: request cancel %s", __func__, c->self, 856 (fwd_desc = format_forward(ftype, &fwd))); 857 858 /* make sure this has been requested */ 859 found_fwd = NULL; 860 switch (ftype) { 861 case MUX_FWD_LOCAL: 862 case MUX_FWD_DYNAMIC: 863 for (i = 0; i < options.num_local_forwards; i++) { 864 if (compare_forward(&fwd, 865 options.local_forwards + i)) { 866 found_fwd = options.local_forwards + i; 867 break; 868 } 869 } 870 break; 871 case MUX_FWD_REMOTE: 872 for (i = 0; i < options.num_remote_forwards; i++) { 873 if (compare_forward(&fwd, 874 options.remote_forwards + i)) { 875 found_fwd = options.remote_forwards + i; 876 break; 877 } 878 } 879 break; 880 } 881 882 if (found_fwd == NULL) 883 error_reason = "port not forwarded"; 884 else if (ftype == MUX_FWD_REMOTE) { 885 /* 886 * This shouldn't fail unless we confused the host/port 887 * between options.remote_forwards and permitted_opens. 888 * However, for dynamic allocated listen ports we need 889 * to use the actual listen port. 890 */ 891 if (channel_request_rforward_cancel(found_fwd) == -1) 892 error_reason = "port not in permitted opens"; 893 } else { /* local and dynamic forwards */ 894 /* Ditto */ 895 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 896 &options.fwd_opts) == -1) 897 error_reason = "port not found"; 898 } 899 900 if (error_reason == NULL) { 901 buffer_put_int(r, MUX_S_OK); 902 buffer_put_int(r, rid); 903 904 free(found_fwd->listen_host); 905 free(found_fwd->listen_path); 906 free(found_fwd->connect_host); 907 free(found_fwd->connect_path); 908 found_fwd->listen_host = found_fwd->connect_host = NULL; 909 found_fwd->listen_path = found_fwd->connect_path = NULL; 910 found_fwd->listen_port = found_fwd->connect_port = 0; 911 } else { 912 buffer_put_int(r, MUX_S_FAILURE); 913 buffer_put_int(r, rid); 914 buffer_put_cstring(r, error_reason); 915 } 916 out: 917 free(fwd_desc); 918 free(listen_addr); 919 free(connect_addr); 920 921 return ret; 922 } 923 924 static int 925 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 926 { 927 Channel *nc; 928 char *reserved, *chost; 929 u_int cport, i, j; 930 int new_fd[2]; 931 struct mux_stdio_confirm_ctx *cctx; 932 933 chost = reserved = NULL; 934 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 935 (chost = buffer_get_string_ret(m, NULL)) == NULL || 936 buffer_get_int_ret(&cport, m) != 0) { 937 free(reserved); 938 free(chost); 939 error("%s: malformed message", __func__); 940 return -1; 941 } 942 free(reserved); 943 944 debug2("%s: channel %d: request stdio fwd to %s:%u", 945 __func__, c->self, chost, cport); 946 947 /* Gather fds from client */ 948 for(i = 0; i < 2; i++) { 949 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 950 error("%s: failed to receive fd %d from slave", 951 __func__, i); 952 for (j = 0; j < i; j++) 953 close(new_fd[j]); 954 free(chost); 955 956 /* prepare reply */ 957 buffer_put_int(r, MUX_S_FAILURE); 958 buffer_put_int(r, rid); 959 buffer_put_cstring(r, 960 "did not receive file descriptors"); 961 return -1; 962 } 963 } 964 965 debug3("%s: got fds stdin %d, stdout %d", __func__, 966 new_fd[0], new_fd[1]); 967 968 /* XXX support multiple child sessions in future */ 969 if (c->remote_id != -1) { 970 debug2("%s: session already open", __func__); 971 /* prepare reply */ 972 buffer_put_int(r, MUX_S_FAILURE); 973 buffer_put_int(r, rid); 974 buffer_put_cstring(r, "Multiple sessions not supported"); 975 cleanup: 976 close(new_fd[0]); 977 close(new_fd[1]); 978 free(chost); 979 return 0; 980 } 981 982 if (options.control_master == SSHCTL_MASTER_ASK || 983 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 984 if (!ask_permission("Allow forward to %s:%u? ", 985 chost, cport)) { 986 debug2("%s: stdio fwd refused by user", __func__); 987 /* prepare reply */ 988 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 989 buffer_put_int(r, rid); 990 buffer_put_cstring(r, "Permission denied"); 991 goto cleanup; 992 } 993 } 994 995 /* enable nonblocking unless tty */ 996 if (!isatty(new_fd[0])) 997 set_nonblock(new_fd[0]); 998 if (!isatty(new_fd[1])) 999 set_nonblock(new_fd[1]); 1000 1001 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 1002 1003 nc->ctl_chan = c->self; /* link session -> control channel */ 1004 c->remote_id = nc->self; /* link control -> session channel */ 1005 1006 debug2("%s: channel_new: %d linked to control channel %d", 1007 __func__, nc->self, nc->ctl_chan); 1008 1009 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 1010 1011 cctx = xcalloc(1, sizeof(*cctx)); 1012 cctx->rid = rid; 1013 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1014 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1015 1016 /* reply is deferred, sent by mux_session_confirm */ 1017 return 0; 1018 } 1019 1020 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1021 static void 1022 mux_stdio_confirm(int id, int success, void *arg) 1023 { 1024 struct mux_stdio_confirm_ctx *cctx = arg; 1025 Channel *c, *cc; 1026 Buffer reply; 1027 1028 if (cctx == NULL) 1029 fatal("%s: cctx == NULL", __func__); 1030 if ((c = channel_by_id(id)) == NULL) 1031 fatal("%s: no channel for id %d", __func__, id); 1032 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1033 fatal("%s: channel %d lacks control channel %d", __func__, 1034 id, c->ctl_chan); 1035 1036 if (!success) { 1037 debug3("%s: sending failure reply", __func__); 1038 /* prepare reply */ 1039 buffer_init(&reply); 1040 buffer_put_int(&reply, MUX_S_FAILURE); 1041 buffer_put_int(&reply, cctx->rid); 1042 buffer_put_cstring(&reply, "Session open refused by peer"); 1043 goto done; 1044 } 1045 1046 debug3("%s: sending success reply", __func__); 1047 /* prepare reply */ 1048 buffer_init(&reply); 1049 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1050 buffer_put_int(&reply, cctx->rid); 1051 buffer_put_int(&reply, c->self); 1052 1053 done: 1054 /* Send reply */ 1055 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1056 buffer_free(&reply); 1057 1058 if (cc->mux_pause <= 0) 1059 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1060 cc->mux_pause = 0; /* start processing messages again */ 1061 c->open_confirm_ctx = NULL; 1062 free(cctx); 1063 } 1064 1065 static int 1066 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1067 { 1068 debug("%s: channel %d: stop listening", __func__, c->self); 1069 1070 if (options.control_master == SSHCTL_MASTER_ASK || 1071 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1072 if (!ask_permission("Disable further multiplexing on shared " 1073 "connection to %s? ", host)) { 1074 debug2("%s: stop listen refused by user", __func__); 1075 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1076 buffer_put_int(r, rid); 1077 buffer_put_cstring(r, "Permission denied"); 1078 return 0; 1079 } 1080 } 1081 1082 if (mux_listener_channel != NULL) { 1083 channel_free(mux_listener_channel); 1084 client_stop_mux(); 1085 free(options.control_path); 1086 options.control_path = NULL; 1087 mux_listener_channel = NULL; 1088 muxserver_sock = -1; 1089 } 1090 1091 /* prepare reply */ 1092 buffer_put_int(r, MUX_S_OK); 1093 buffer_put_int(r, rid); 1094 1095 return 0; 1096 } 1097 1098 /* Channel callbacks fired on read/write from mux slave fd */ 1099 static int 1100 mux_master_read_cb(Channel *c) 1101 { 1102 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1103 Buffer in, out; 1104 const u_char *ptr; 1105 u_int type, rid, have, i; 1106 int ret = -1; 1107 1108 /* Setup ctx and */ 1109 if (c->mux_ctx == NULL) { 1110 state = xcalloc(1, sizeof(*state)); 1111 c->mux_ctx = state; 1112 channel_register_cleanup(c->self, 1113 mux_master_control_cleanup_cb, 0); 1114 1115 /* Send hello */ 1116 buffer_init(&out); 1117 buffer_put_int(&out, MUX_MSG_HELLO); 1118 buffer_put_int(&out, SSHMUX_VER); 1119 /* no extensions */ 1120 buffer_put_string(&c->output, buffer_ptr(&out), 1121 buffer_len(&out)); 1122 buffer_free(&out); 1123 debug3("%s: channel %d: hello sent", __func__, c->self); 1124 return 0; 1125 } 1126 1127 buffer_init(&in); 1128 buffer_init(&out); 1129 1130 /* Channel code ensures that we receive whole packets */ 1131 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1132 malf: 1133 error("%s: malformed message", __func__); 1134 goto out; 1135 } 1136 buffer_append(&in, ptr, have); 1137 1138 if (buffer_get_int_ret(&type, &in) != 0) 1139 goto malf; 1140 debug3("%s: channel %d packet type 0x%08x len %u", 1141 __func__, c->self, type, buffer_len(&in)); 1142 1143 if (type == MUX_MSG_HELLO) 1144 rid = 0; 1145 else { 1146 if (!state->hello_rcvd) { 1147 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1148 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1149 goto out; 1150 } 1151 if (buffer_get_int_ret(&rid, &in) != 0) 1152 goto malf; 1153 } 1154 1155 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1156 if (type == mux_master_handlers[i].type) { 1157 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1158 break; 1159 } 1160 } 1161 if (mux_master_handlers[i].handler == NULL) { 1162 error("%s: unsupported mux message 0x%08x", __func__, type); 1163 buffer_put_int(&out, MUX_S_FAILURE); 1164 buffer_put_int(&out, rid); 1165 buffer_put_cstring(&out, "unsupported request"); 1166 ret = 0; 1167 } 1168 /* Enqueue reply packet */ 1169 if (buffer_len(&out) != 0) { 1170 buffer_put_string(&c->output, buffer_ptr(&out), 1171 buffer_len(&out)); 1172 } 1173 out: 1174 buffer_free(&in); 1175 buffer_free(&out); 1176 return ret; 1177 } 1178 1179 void 1180 mux_exit_message(Channel *c, int exitval) 1181 { 1182 Buffer m; 1183 Channel *mux_chan; 1184 1185 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1186 exitval); 1187 1188 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1189 fatal("%s: channel %d missing mux channel %d", 1190 __func__, c->self, c->ctl_chan); 1191 1192 /* Append exit message packet to control socket output queue */ 1193 buffer_init(&m); 1194 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1195 buffer_put_int(&m, c->self); 1196 buffer_put_int(&m, exitval); 1197 1198 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1199 buffer_free(&m); 1200 } 1201 1202 void 1203 mux_tty_alloc_failed(Channel *c) 1204 { 1205 Buffer m; 1206 Channel *mux_chan; 1207 1208 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1209 1210 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1211 fatal("%s: channel %d missing mux channel %d", 1212 __func__, c->self, c->ctl_chan); 1213 1214 /* Append exit message packet to control socket output queue */ 1215 buffer_init(&m); 1216 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1217 buffer_put_int(&m, c->self); 1218 1219 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1220 buffer_free(&m); 1221 } 1222 1223 /* Prepare a mux master to listen on a Unix domain socket. */ 1224 void 1225 muxserver_listen(void) 1226 { 1227 mode_t old_umask; 1228 char *orig_control_path = options.control_path; 1229 char rbuf[16+1]; 1230 u_int i, r; 1231 int oerrno; 1232 1233 if (options.control_path == NULL || 1234 options.control_master == SSHCTL_MASTER_NO) 1235 return; 1236 1237 debug("setting up multiplex master socket"); 1238 1239 /* 1240 * Use a temporary path before listen so we can pseudo-atomically 1241 * establish the listening socket in its final location to avoid 1242 * other processes racing in between bind() and listen() and hitting 1243 * an unready socket. 1244 */ 1245 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1246 r = arc4random_uniform(26+26+10); 1247 rbuf[i] = (r < 26) ? 'a' + r : 1248 (r < 26*2) ? 'A' + r - 26 : 1249 '0' + r - 26 - 26; 1250 } 1251 rbuf[sizeof(rbuf) - 1] = '\0'; 1252 options.control_path = NULL; 1253 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1254 debug3("%s: temporary control path %s", __func__, options.control_path); 1255 1256 old_umask = umask(0177); 1257 muxserver_sock = unix_listener(options.control_path, 64, 0); 1258 oerrno = errno; 1259 umask(old_umask); 1260 if (muxserver_sock < 0) { 1261 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1262 error("ControlSocket %s already exists, " 1263 "disabling multiplexing", options.control_path); 1264 disable_mux_master: 1265 if (muxserver_sock != -1) { 1266 close(muxserver_sock); 1267 muxserver_sock = -1; 1268 } 1269 free(orig_control_path); 1270 free(options.control_path); 1271 options.control_path = NULL; 1272 options.control_master = SSHCTL_MASTER_NO; 1273 return; 1274 } else { 1275 /* unix_listener() logs the error */ 1276 cleanup_exit(255); 1277 } 1278 } 1279 1280 /* Now atomically "move" the mux socket into position */ 1281 if (link(options.control_path, orig_control_path) != 0) { 1282 if (errno != EEXIST) { 1283 fatal("%s: link mux listener %s => %s: %s", __func__, 1284 options.control_path, orig_control_path, 1285 strerror(errno)); 1286 } 1287 error("ControlSocket %s already exists, disabling multiplexing", 1288 orig_control_path); 1289 unlink(options.control_path); 1290 goto disable_mux_master; 1291 } 1292 unlink(options.control_path); 1293 free(options.control_path); 1294 options.control_path = orig_control_path; 1295 1296 set_nonblock(muxserver_sock); 1297 1298 mux_listener_channel = channel_new("mux listener", 1299 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1300 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1301 0, options.control_path, 1); 1302 mux_listener_channel->mux_rcb = mux_master_read_cb; 1303 debug3("%s: mux listener channel %d fd %d", __func__, 1304 mux_listener_channel->self, mux_listener_channel->sock); 1305 } 1306 1307 /* Callback on open confirmation in mux master for a mux client session. */ 1308 static void 1309 mux_session_confirm(int id, int success, void *arg) 1310 { 1311 struct mux_session_confirm_ctx *cctx = arg; 1312 const char *display; 1313 Channel *c, *cc; 1314 int i; 1315 Buffer reply; 1316 1317 if (cctx == NULL) 1318 fatal("%s: cctx == NULL", __func__); 1319 if ((c = channel_by_id(id)) == NULL) 1320 fatal("%s: no channel for id %d", __func__, id); 1321 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1322 fatal("%s: channel %d lacks control channel %d", __func__, 1323 id, c->ctl_chan); 1324 1325 if (!success) { 1326 debug3("%s: sending failure reply", __func__); 1327 /* prepare reply */ 1328 buffer_init(&reply); 1329 buffer_put_int(&reply, MUX_S_FAILURE); 1330 buffer_put_int(&reply, cctx->rid); 1331 buffer_put_cstring(&reply, "Session open refused by peer"); 1332 goto done; 1333 } 1334 1335 display = getenv("DISPLAY"); 1336 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1337 char *proto, *data; 1338 1339 /* Get reasonable local authentication information. */ 1340 client_x11_get_proto(display, options.xauth_location, 1341 options.forward_x11_trusted, options.forward_x11_timeout, 1342 &proto, &data); 1343 /* Request forwarding with authentication spoofing. */ 1344 debug("Requesting X11 forwarding with authentication " 1345 "spoofing."); 1346 x11_request_forwarding_with_spoofing(id, display, proto, 1347 data, 1); 1348 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1349 /* XXX exit_on_forward_failure */ 1350 } 1351 1352 if (cctx->want_agent_fwd && options.forward_agent) { 1353 debug("Requesting authentication agent forwarding."); 1354 channel_request_start(id, "auth-agent-req (at) openssh.com", 0); 1355 packet_send(); 1356 } 1357 1358 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1359 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1360 1361 debug3("%s: sending success reply", __func__); 1362 /* prepare reply */ 1363 buffer_init(&reply); 1364 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1365 buffer_put_int(&reply, cctx->rid); 1366 buffer_put_int(&reply, c->self); 1367 1368 done: 1369 /* Send reply */ 1370 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1371 buffer_free(&reply); 1372 1373 if (cc->mux_pause <= 0) 1374 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1375 cc->mux_pause = 0; /* start processing messages again */ 1376 c->open_confirm_ctx = NULL; 1377 buffer_free(&cctx->cmd); 1378 free(cctx->term); 1379 if (cctx->env != NULL) { 1380 for (i = 0; cctx->env[i] != NULL; i++) 1381 free(cctx->env[i]); 1382 free(cctx->env); 1383 } 1384 free(cctx); 1385 } 1386 1387 /* ** Multiplexing client support */ 1388 1389 /* Exit signal handler */ 1390 static void 1391 control_client_sighandler(int signo) 1392 { 1393 muxclient_terminate = signo; 1394 } 1395 1396 /* 1397 * Relay signal handler - used to pass some signals from mux client to 1398 * mux master. 1399 */ 1400 static void 1401 control_client_sigrelay(int signo) 1402 { 1403 int save_errno = errno; 1404 1405 if (muxserver_pid > 1) 1406 kill(muxserver_pid, signo); 1407 1408 errno = save_errno; 1409 } 1410 1411 static int 1412 mux_client_read(int fd, Buffer *b, u_int need) 1413 { 1414 u_int have; 1415 ssize_t len; 1416 u_char *p; 1417 struct pollfd pfd; 1418 1419 pfd.fd = fd; 1420 pfd.events = POLLIN; 1421 p = buffer_append_space(b, need); 1422 for (have = 0; have < need; ) { 1423 if (muxclient_terminate) { 1424 errno = EINTR; 1425 return -1; 1426 } 1427 len = read(fd, p + have, need - have); 1428 if (len < 0) { 1429 switch (errno) { 1430 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1431 case EWOULDBLOCK: 1432 #endif 1433 case EAGAIN: 1434 (void)poll(&pfd, 1, -1); 1435 /* FALLTHROUGH */ 1436 case EINTR: 1437 continue; 1438 default: 1439 return -1; 1440 } 1441 } 1442 if (len == 0) { 1443 errno = EPIPE; 1444 return -1; 1445 } 1446 have += (u_int)len; 1447 } 1448 return 0; 1449 } 1450 1451 static int 1452 mux_client_write_packet(int fd, Buffer *m) 1453 { 1454 Buffer queue; 1455 u_int have, need; 1456 int oerrno, len; 1457 u_char *ptr; 1458 struct pollfd pfd; 1459 1460 pfd.fd = fd; 1461 pfd.events = POLLOUT; 1462 buffer_init(&queue); 1463 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1464 1465 need = buffer_len(&queue); 1466 ptr = buffer_ptr(&queue); 1467 1468 for (have = 0; have < need; ) { 1469 if (muxclient_terminate) { 1470 buffer_free(&queue); 1471 errno = EINTR; 1472 return -1; 1473 } 1474 len = write(fd, ptr + have, need - have); 1475 if (len < 0) { 1476 switch (errno) { 1477 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1478 case EWOULDBLOCK: 1479 #endif 1480 case EAGAIN: 1481 (void)poll(&pfd, 1, -1); 1482 /* FALLTHROUGH */ 1483 case EINTR: 1484 continue; 1485 default: 1486 oerrno = errno; 1487 buffer_free(&queue); 1488 errno = oerrno; 1489 return -1; 1490 } 1491 } 1492 if (len == 0) { 1493 buffer_free(&queue); 1494 errno = EPIPE; 1495 return -1; 1496 } 1497 have += (u_int)len; 1498 } 1499 buffer_free(&queue); 1500 return 0; 1501 } 1502 1503 static int 1504 mux_client_read_packet(int fd, Buffer *m) 1505 { 1506 Buffer queue; 1507 u_int need, have; 1508 const u_char *ptr; 1509 int oerrno; 1510 1511 buffer_init(&queue); 1512 if (mux_client_read(fd, &queue, 4) != 0) { 1513 if ((oerrno = errno) == EPIPE) 1514 debug3("%s: read header failed: %s", __func__, 1515 strerror(errno)); 1516 buffer_free(&queue); 1517 errno = oerrno; 1518 return -1; 1519 } 1520 need = get_u32(buffer_ptr(&queue)); 1521 if (mux_client_read(fd, &queue, need) != 0) { 1522 oerrno = errno; 1523 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1524 buffer_free(&queue); 1525 errno = oerrno; 1526 return -1; 1527 } 1528 ptr = buffer_get_string_ptr(&queue, &have); 1529 buffer_append(m, ptr, have); 1530 buffer_free(&queue); 1531 return 0; 1532 } 1533 1534 static int 1535 mux_client_hello_exchange(int fd) 1536 { 1537 Buffer m; 1538 u_int type, ver; 1539 1540 buffer_init(&m); 1541 buffer_put_int(&m, MUX_MSG_HELLO); 1542 buffer_put_int(&m, SSHMUX_VER); 1543 /* no extensions */ 1544 1545 if (mux_client_write_packet(fd, &m) != 0) 1546 fatal("%s: write packet: %s", __func__, strerror(errno)); 1547 1548 buffer_clear(&m); 1549 1550 /* Read their HELLO */ 1551 if (mux_client_read_packet(fd, &m) != 0) { 1552 buffer_free(&m); 1553 return -1; 1554 } 1555 1556 type = buffer_get_int(&m); 1557 if (type != MUX_MSG_HELLO) 1558 fatal("%s: expected HELLO (%u) received %u", 1559 __func__, MUX_MSG_HELLO, type); 1560 ver = buffer_get_int(&m); 1561 if (ver != SSHMUX_VER) 1562 fatal("Unsupported multiplexing protocol version %d " 1563 "(expected %d)", ver, SSHMUX_VER); 1564 debug2("%s: master version %u", __func__, ver); 1565 /* No extensions are presently defined */ 1566 while (buffer_len(&m) > 0) { 1567 char *name = buffer_get_string(&m, NULL); 1568 char *value = buffer_get_string(&m, NULL); 1569 1570 debug2("Unrecognised master extension \"%s\"", name); 1571 free(name); 1572 free(value); 1573 } 1574 buffer_free(&m); 1575 return 0; 1576 } 1577 1578 static u_int 1579 mux_client_request_alive(int fd) 1580 { 1581 Buffer m; 1582 char *e; 1583 u_int pid, type, rid; 1584 1585 debug3("%s: entering", __func__); 1586 1587 buffer_init(&m); 1588 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1589 buffer_put_int(&m, muxclient_request_id); 1590 1591 if (mux_client_write_packet(fd, &m) != 0) 1592 fatal("%s: write packet: %s", __func__, strerror(errno)); 1593 1594 buffer_clear(&m); 1595 1596 /* Read their reply */ 1597 if (mux_client_read_packet(fd, &m) != 0) { 1598 buffer_free(&m); 1599 return 0; 1600 } 1601 1602 type = buffer_get_int(&m); 1603 if (type != MUX_S_ALIVE) { 1604 e = buffer_get_string(&m, NULL); 1605 fatal("%s: master returned error: %s", __func__, e); 1606 } 1607 1608 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1609 fatal("%s: out of sequence reply: my id %u theirs %u", 1610 __func__, muxclient_request_id, rid); 1611 pid = buffer_get_int(&m); 1612 buffer_free(&m); 1613 1614 debug3("%s: done pid = %u", __func__, pid); 1615 1616 muxclient_request_id++; 1617 1618 return pid; 1619 } 1620 1621 static void 1622 mux_client_request_terminate(int fd) 1623 { 1624 Buffer m; 1625 char *e; 1626 u_int type, rid; 1627 1628 debug3("%s: entering", __func__); 1629 1630 buffer_init(&m); 1631 buffer_put_int(&m, MUX_C_TERMINATE); 1632 buffer_put_int(&m, muxclient_request_id); 1633 1634 if (mux_client_write_packet(fd, &m) != 0) 1635 fatal("%s: write packet: %s", __func__, strerror(errno)); 1636 1637 buffer_clear(&m); 1638 1639 /* Read their reply */ 1640 if (mux_client_read_packet(fd, &m) != 0) { 1641 /* Remote end exited already */ 1642 if (errno == EPIPE) { 1643 buffer_free(&m); 1644 return; 1645 } 1646 fatal("%s: read from master failed: %s", 1647 __func__, strerror(errno)); 1648 } 1649 1650 type = buffer_get_int(&m); 1651 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1652 fatal("%s: out of sequence reply: my id %u theirs %u", 1653 __func__, muxclient_request_id, rid); 1654 switch (type) { 1655 case MUX_S_OK: 1656 break; 1657 case MUX_S_PERMISSION_DENIED: 1658 e = buffer_get_string(&m, NULL); 1659 fatal("Master refused termination request: %s", e); 1660 case MUX_S_FAILURE: 1661 e = buffer_get_string(&m, NULL); 1662 fatal("%s: termination request failed: %s", __func__, e); 1663 default: 1664 fatal("%s: unexpected response from master 0x%08x", 1665 __func__, type); 1666 } 1667 buffer_free(&m); 1668 muxclient_request_id++; 1669 } 1670 1671 static int 1672 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1673 { 1674 Buffer m; 1675 char *e, *fwd_desc; 1676 u_int type, rid; 1677 1678 fwd_desc = format_forward(ftype, fwd); 1679 debug("Requesting %s %s", 1680 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1681 free(fwd_desc); 1682 1683 buffer_init(&m); 1684 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1685 buffer_put_int(&m, muxclient_request_id); 1686 buffer_put_int(&m, ftype); 1687 if (fwd->listen_path != NULL) { 1688 buffer_put_cstring(&m, fwd->listen_path); 1689 } else { 1690 buffer_put_cstring(&m, 1691 fwd->listen_host == NULL ? "" : 1692 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1693 } 1694 buffer_put_int(&m, fwd->listen_port); 1695 if (fwd->connect_path != NULL) { 1696 buffer_put_cstring(&m, fwd->connect_path); 1697 } else { 1698 buffer_put_cstring(&m, 1699 fwd->connect_host == NULL ? "" : fwd->connect_host); 1700 } 1701 buffer_put_int(&m, fwd->connect_port); 1702 1703 if (mux_client_write_packet(fd, &m) != 0) 1704 fatal("%s: write packet: %s", __func__, strerror(errno)); 1705 1706 buffer_clear(&m); 1707 1708 /* Read their reply */ 1709 if (mux_client_read_packet(fd, &m) != 0) { 1710 buffer_free(&m); 1711 return -1; 1712 } 1713 1714 type = buffer_get_int(&m); 1715 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1716 fatal("%s: out of sequence reply: my id %u theirs %u", 1717 __func__, muxclient_request_id, rid); 1718 switch (type) { 1719 case MUX_S_OK: 1720 break; 1721 case MUX_S_REMOTE_PORT: 1722 if (cancel_flag) 1723 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1724 fwd->allocated_port = buffer_get_int(&m); 1725 logit("Allocated port %u for remote forward to %s:%d", 1726 fwd->allocated_port, 1727 fwd->connect_host ? fwd->connect_host : "", 1728 fwd->connect_port); 1729 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1730 fprintf(stdout, "%u\n", fwd->allocated_port); 1731 break; 1732 case MUX_S_PERMISSION_DENIED: 1733 e = buffer_get_string(&m, NULL); 1734 buffer_free(&m); 1735 error("Master refused forwarding request: %s", e); 1736 return -1; 1737 case MUX_S_FAILURE: 1738 e = buffer_get_string(&m, NULL); 1739 buffer_free(&m); 1740 error("%s: forwarding request failed: %s", __func__, e); 1741 return -1; 1742 default: 1743 fatal("%s: unexpected response from master 0x%08x", 1744 __func__, type); 1745 } 1746 buffer_free(&m); 1747 1748 muxclient_request_id++; 1749 return 0; 1750 } 1751 1752 static int 1753 mux_client_forwards(int fd, int cancel_flag) 1754 { 1755 int i, ret = 0; 1756 1757 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1758 cancel_flag ? "cancel" : "request", 1759 options.num_local_forwards, options.num_remote_forwards); 1760 1761 /* XXX ExitOnForwardingFailure */ 1762 for (i = 0; i < options.num_local_forwards; i++) { 1763 if (mux_client_forward(fd, cancel_flag, 1764 options.local_forwards[i].connect_port == 0 ? 1765 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1766 options.local_forwards + i) != 0) 1767 ret = -1; 1768 } 1769 for (i = 0; i < options.num_remote_forwards; i++) { 1770 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1771 options.remote_forwards + i) != 0) 1772 ret = -1; 1773 } 1774 return ret; 1775 } 1776 1777 static int 1778 mux_client_request_session(int fd) 1779 { 1780 Buffer m; 1781 char *e, *term; 1782 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1783 extern char **environ; 1784 int devnull, rawmode; 1785 1786 debug3("%s: entering", __func__); 1787 1788 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1789 error("%s: master alive request failed", __func__); 1790 return -1; 1791 } 1792 1793 signal(SIGPIPE, SIG_IGN); 1794 1795 if (stdin_null_flag) { 1796 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1797 fatal("open(/dev/null): %s", strerror(errno)); 1798 if (dup2(devnull, STDIN_FILENO) == -1) 1799 fatal("dup2: %s", strerror(errno)); 1800 if (devnull > STDERR_FILENO) 1801 close(devnull); 1802 } 1803 1804 term = getenv("TERM"); 1805 1806 buffer_init(&m); 1807 buffer_put_int(&m, MUX_C_NEW_SESSION); 1808 buffer_put_int(&m, muxclient_request_id); 1809 buffer_put_cstring(&m, ""); /* reserved */ 1810 buffer_put_int(&m, tty_flag); 1811 buffer_put_int(&m, options.forward_x11); 1812 buffer_put_int(&m, options.forward_agent); 1813 buffer_put_int(&m, subsystem_flag); 1814 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1815 0xffffffff : (u_int)options.escape_char); 1816 buffer_put_cstring(&m, term == NULL ? "" : term); 1817 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1818 1819 if (options.num_send_env > 0 && environ != NULL) { 1820 /* Pass environment */ 1821 for (i = 0; environ[i] != NULL; i++) { 1822 if (env_permitted(environ[i])) { 1823 buffer_put_cstring(&m, environ[i]); 1824 } 1825 } 1826 } 1827 1828 if (mux_client_write_packet(fd, &m) != 0) 1829 fatal("%s: write packet: %s", __func__, strerror(errno)); 1830 1831 /* Send the stdio file descriptors */ 1832 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1833 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1834 mm_send_fd(fd, STDERR_FILENO) == -1) 1835 fatal("%s: send fds failed", __func__); 1836 1837 debug3("%s: session request sent", __func__); 1838 1839 /* Read their reply */ 1840 buffer_clear(&m); 1841 if (mux_client_read_packet(fd, &m) != 0) { 1842 error("%s: read from master failed: %s", 1843 __func__, strerror(errno)); 1844 buffer_free(&m); 1845 return -1; 1846 } 1847 1848 type = buffer_get_int(&m); 1849 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1850 fatal("%s: out of sequence reply: my id %u theirs %u", 1851 __func__, muxclient_request_id, rid); 1852 switch (type) { 1853 case MUX_S_SESSION_OPENED: 1854 sid = buffer_get_int(&m); 1855 debug("%s: master session id: %u", __func__, sid); 1856 break; 1857 case MUX_S_PERMISSION_DENIED: 1858 e = buffer_get_string(&m, NULL); 1859 buffer_free(&m); 1860 error("Master refused session request: %s", e); 1861 return -1; 1862 case MUX_S_FAILURE: 1863 e = buffer_get_string(&m, NULL); 1864 buffer_free(&m); 1865 error("%s: session request failed: %s", __func__, e); 1866 return -1; 1867 default: 1868 buffer_free(&m); 1869 error("%s: unexpected response from master 0x%08x", 1870 __func__, type); 1871 return -1; 1872 } 1873 muxclient_request_id++; 1874 1875 signal(SIGHUP, control_client_sighandler); 1876 signal(SIGINT, control_client_sighandler); 1877 signal(SIGTERM, control_client_sighandler); 1878 signal(SIGWINCH, control_client_sigrelay); 1879 1880 rawmode = tty_flag; 1881 if (tty_flag) 1882 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1883 1884 /* 1885 * Stick around until the controlee closes the client_fd. 1886 * Before it does, it is expected to write an exit message. 1887 * This process must read the value and wait for the closure of 1888 * the client_fd; if this one closes early, the multiplex master will 1889 * terminate early too (possibly losing data). 1890 */ 1891 for (exitval = 255, exitval_seen = 0;;) { 1892 buffer_clear(&m); 1893 if (mux_client_read_packet(fd, &m) != 0) 1894 break; 1895 type = buffer_get_int(&m); 1896 switch (type) { 1897 case MUX_S_TTY_ALLOC_FAIL: 1898 if ((esid = buffer_get_int(&m)) != sid) 1899 fatal("%s: tty alloc fail on unknown session: " 1900 "my id %u theirs %u", 1901 __func__, sid, esid); 1902 leave_raw_mode(options.request_tty == 1903 REQUEST_TTY_FORCE); 1904 rawmode = 0; 1905 continue; 1906 case MUX_S_EXIT_MESSAGE: 1907 if ((esid = buffer_get_int(&m)) != sid) 1908 fatal("%s: exit on unknown session: " 1909 "my id %u theirs %u", 1910 __func__, sid, esid); 1911 if (exitval_seen) 1912 fatal("%s: exitval sent twice", __func__); 1913 exitval = buffer_get_int(&m); 1914 exitval_seen = 1; 1915 continue; 1916 default: 1917 e = buffer_get_string(&m, NULL); 1918 fatal("%s: master returned error: %s", __func__, e); 1919 } 1920 } 1921 1922 close(fd); 1923 if (rawmode) 1924 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1925 1926 if (muxclient_terminate) { 1927 debug2("Exiting on signal %d", muxclient_terminate); 1928 exitval = 255; 1929 } else if (!exitval_seen) { 1930 debug2("Control master terminated unexpectedly"); 1931 exitval = 255; 1932 } else 1933 debug2("Received exit status from master %d", exitval); 1934 1935 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1936 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1937 1938 exit(exitval); 1939 } 1940 1941 static int 1942 mux_client_request_stdio_fwd(int fd) 1943 { 1944 Buffer m; 1945 char *e; 1946 u_int type, rid, sid; 1947 int devnull; 1948 1949 debug3("%s: entering", __func__); 1950 1951 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1952 error("%s: master alive request failed", __func__); 1953 return -1; 1954 } 1955 1956 signal(SIGPIPE, SIG_IGN); 1957 1958 if (stdin_null_flag) { 1959 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1960 fatal("open(/dev/null): %s", strerror(errno)); 1961 if (dup2(devnull, STDIN_FILENO) == -1) 1962 fatal("dup2: %s", strerror(errno)); 1963 if (devnull > STDERR_FILENO) 1964 close(devnull); 1965 } 1966 1967 buffer_init(&m); 1968 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1969 buffer_put_int(&m, muxclient_request_id); 1970 buffer_put_cstring(&m, ""); /* reserved */ 1971 buffer_put_cstring(&m, stdio_forward_host); 1972 buffer_put_int(&m, stdio_forward_port); 1973 1974 if (mux_client_write_packet(fd, &m) != 0) 1975 fatal("%s: write packet: %s", __func__, strerror(errno)); 1976 1977 /* Send the stdio file descriptors */ 1978 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1979 mm_send_fd(fd, STDOUT_FILENO) == -1) 1980 fatal("%s: send fds failed", __func__); 1981 1982 debug3("%s: stdio forward request sent", __func__); 1983 1984 /* Read their reply */ 1985 buffer_clear(&m); 1986 1987 if (mux_client_read_packet(fd, &m) != 0) { 1988 error("%s: read from master failed: %s", 1989 __func__, strerror(errno)); 1990 buffer_free(&m); 1991 return -1; 1992 } 1993 1994 type = buffer_get_int(&m); 1995 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1996 fatal("%s: out of sequence reply: my id %u theirs %u", 1997 __func__, muxclient_request_id, rid); 1998 switch (type) { 1999 case MUX_S_SESSION_OPENED: 2000 sid = buffer_get_int(&m); 2001 debug("%s: master session id: %u", __func__, sid); 2002 break; 2003 case MUX_S_PERMISSION_DENIED: 2004 e = buffer_get_string(&m, NULL); 2005 buffer_free(&m); 2006 fatal("Master refused stdio forwarding request: %s", e); 2007 case MUX_S_FAILURE: 2008 e = buffer_get_string(&m, NULL); 2009 buffer_free(&m); 2010 fatal("Stdio forwarding request failed: %s", e); 2011 default: 2012 buffer_free(&m); 2013 error("%s: unexpected response from master 0x%08x", 2014 __func__, type); 2015 return -1; 2016 } 2017 muxclient_request_id++; 2018 2019 signal(SIGHUP, control_client_sighandler); 2020 signal(SIGINT, control_client_sighandler); 2021 signal(SIGTERM, control_client_sighandler); 2022 signal(SIGWINCH, control_client_sigrelay); 2023 2024 /* 2025 * Stick around until the controlee closes the client_fd. 2026 */ 2027 buffer_clear(&m); 2028 if (mux_client_read_packet(fd, &m) != 0) { 2029 if (errno == EPIPE || 2030 (errno == EINTR && muxclient_terminate != 0)) 2031 return 0; 2032 fatal("%s: mux_client_read_packet: %s", 2033 __func__, strerror(errno)); 2034 } 2035 fatal("%s: master returned unexpected message %u", __func__, type); 2036 } 2037 2038 static void 2039 mux_client_request_stop_listening(int fd) 2040 { 2041 Buffer m; 2042 char *e; 2043 u_int type, rid; 2044 2045 debug3("%s: entering", __func__); 2046 2047 buffer_init(&m); 2048 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2049 buffer_put_int(&m, muxclient_request_id); 2050 2051 if (mux_client_write_packet(fd, &m) != 0) 2052 fatal("%s: write packet: %s", __func__, strerror(errno)); 2053 2054 buffer_clear(&m); 2055 2056 /* Read their reply */ 2057 if (mux_client_read_packet(fd, &m) != 0) 2058 fatal("%s: read from master failed: %s", 2059 __func__, strerror(errno)); 2060 2061 type = buffer_get_int(&m); 2062 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2063 fatal("%s: out of sequence reply: my id %u theirs %u", 2064 __func__, muxclient_request_id, rid); 2065 switch (type) { 2066 case MUX_S_OK: 2067 break; 2068 case MUX_S_PERMISSION_DENIED: 2069 e = buffer_get_string(&m, NULL); 2070 fatal("Master refused stop listening request: %s", e); 2071 case MUX_S_FAILURE: 2072 e = buffer_get_string(&m, NULL); 2073 fatal("%s: stop listening request failed: %s", __func__, e); 2074 default: 2075 fatal("%s: unexpected response from master 0x%08x", 2076 __func__, type); 2077 } 2078 buffer_free(&m); 2079 muxclient_request_id++; 2080 } 2081 2082 /* Multiplex client main loop. */ 2083 void 2084 muxclient(const char *path) 2085 { 2086 struct sockaddr_un addr; 2087 socklen_t sun_len; 2088 int sock; 2089 u_int pid; 2090 2091 if (muxclient_command == 0) { 2092 if (stdio_forward_host != NULL) 2093 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2094 else 2095 muxclient_command = SSHMUX_COMMAND_OPEN; 2096 } 2097 2098 switch (options.control_master) { 2099 case SSHCTL_MASTER_AUTO: 2100 case SSHCTL_MASTER_AUTO_ASK: 2101 debug("auto-mux: Trying existing master"); 2102 /* FALLTHROUGH */ 2103 case SSHCTL_MASTER_NO: 2104 break; 2105 default: 2106 return; 2107 } 2108 2109 memset(&addr, '\0', sizeof(addr)); 2110 addr.sun_family = AF_UNIX; 2111 sun_len = offsetof(struct sockaddr_un, sun_path) + 2112 strlen(path) + 1; 2113 2114 if (strlcpy(addr.sun_path, path, 2115 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2116 fatal("ControlPath too long"); 2117 2118 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2119 fatal("%s socket(): %s", __func__, strerror(errno)); 2120 2121 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 2122 switch (muxclient_command) { 2123 case SSHMUX_COMMAND_OPEN: 2124 case SSHMUX_COMMAND_STDIO_FWD: 2125 break; 2126 default: 2127 fatal("Control socket connect(%.100s): %s", path, 2128 strerror(errno)); 2129 } 2130 if (errno == ECONNREFUSED && 2131 options.control_master != SSHCTL_MASTER_NO) { 2132 debug("Stale control socket %.100s, unlinking", path); 2133 unlink(path); 2134 } else if (errno == ENOENT) { 2135 debug("Control socket \"%.100s\" does not exist", path); 2136 } else { 2137 error("Control socket connect(%.100s): %s", path, 2138 strerror(errno)); 2139 } 2140 close(sock); 2141 return; 2142 } 2143 set_nonblock(sock); 2144 2145 if (mux_client_hello_exchange(sock) != 0) { 2146 error("%s: master hello exchange failed", __func__); 2147 close(sock); 2148 return; 2149 } 2150 2151 switch (muxclient_command) { 2152 case SSHMUX_COMMAND_ALIVE_CHECK: 2153 if ((pid = mux_client_request_alive(sock)) == 0) 2154 fatal("%s: master alive check failed", __func__); 2155 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2156 exit(0); 2157 case SSHMUX_COMMAND_TERMINATE: 2158 mux_client_request_terminate(sock); 2159 fprintf(stderr, "Exit request sent.\r\n"); 2160 exit(0); 2161 case SSHMUX_COMMAND_FORWARD: 2162 if (mux_client_forwards(sock, 0) != 0) 2163 fatal("%s: master forward request failed", __func__); 2164 exit(0); 2165 case SSHMUX_COMMAND_OPEN: 2166 if (mux_client_forwards(sock, 0) != 0) { 2167 error("%s: master forward request failed", __func__); 2168 return; 2169 } 2170 mux_client_request_session(sock); 2171 return; 2172 case SSHMUX_COMMAND_STDIO_FWD: 2173 mux_client_request_stdio_fwd(sock); 2174 exit(0); 2175 case SSHMUX_COMMAND_STOP: 2176 mux_client_request_stop_listening(sock); 2177 fprintf(stderr, "Stop listening request sent.\r\n"); 2178 exit(0); 2179 case SSHMUX_COMMAND_CANCEL_FWD: 2180 if (mux_client_forwards(sock, 1) != 0) 2181 error("%s: master cancel forward request failed", 2182 __func__); 2183 exit(0); 2184 default: 2185 fatal("unrecognised muxclient_command %d", muxclient_command); 2186 } 2187 } 2188
