1 /* $OpenBSD: mux.c,v 1.48 2014/07/17 07:22:19 djm Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 /* 21 * TODO: 22 * - Better signalling from master to slave, especially passing of 23 * error messages 24 * - Better fall-back from mux slave error to new connection. 25 * - ExitOnForwardingFailure 26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 27 * - Support ~^Z in mux slaves. 28 * - Inspect or control sessions in master. 29 * - If we ever support the "signal" channel request, send signals on 30 * sessions in master. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/param.h> 35 #include <sys/queue.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 <poll.h> 43 #include <signal.h> 44 #include <stdarg.h> 45 #include <stddef.h> 46 #include <stdlib.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <unistd.h> 50 #include <util.h> 51 #include <paths.h> 52 53 #include "atomicio.h" 54 #include "xmalloc.h" 55 #include "log.h" 56 #include "ssh.h" 57 #include "ssh2.h" 58 #include "pathnames.h" 59 #include "misc.h" 60 #include "match.h" 61 #include "buffer.h" 62 #include "channels.h" 63 #include "msg.h" 64 #include "packet.h" 65 #include "monitor_fdpass.h" 66 #include "sshpty.h" 67 #include "key.h" 68 #include "readconf.h" 69 #include "clientloop.h" 70 71 /* from ssh.c */ 72 extern int tty_flag; 73 extern Options options; 74 extern int stdin_null_flag; 75 extern char *host; 76 extern int subsystem_flag; 77 extern Buffer command; 78 extern volatile sig_atomic_t quit_pending; 79 extern char *stdio_forward_host; 80 extern int stdio_forward_port; 81 82 /* Context for session open confirmation callback */ 83 struct mux_session_confirm_ctx { 84 u_int want_tty; 85 u_int want_subsys; 86 u_int want_x_fwd; 87 u_int want_agent_fwd; 88 Buffer cmd; 89 char *term; 90 struct termios tio; 91 char **env; 92 u_int rid; 93 }; 94 95 /* Context for stdio fwd open confirmation callback */ 96 struct mux_stdio_confirm_ctx { 97 u_int rid; 98 }; 99 100 /* Context for global channel callback */ 101 struct mux_channel_confirm_ctx { 102 u_int cid; /* channel id */ 103 u_int rid; /* request id */ 104 int fid; /* forward id */ 105 }; 106 107 /* fd to control socket */ 108 int muxserver_sock = -1; 109 110 /* client request id */ 111 u_int muxclient_request_id = 0; 112 113 /* Multiplexing control command */ 114 u_int muxclient_command = 0; 115 116 /* Set when signalled. */ 117 static volatile sig_atomic_t muxclient_terminate = 0; 118 119 /* PID of multiplex server */ 120 static u_int muxserver_pid = 0; 121 122 static Channel *mux_listener_channel = NULL; 123 124 struct mux_master_state { 125 int hello_rcvd; 126 }; 127 128 /* mux protocol messages */ 129 #define MUX_MSG_HELLO 0x00000001 130 #define MUX_C_NEW_SESSION 0x10000002 131 #define MUX_C_ALIVE_CHECK 0x10000004 132 #define MUX_C_TERMINATE 0x10000005 133 #define MUX_C_OPEN_FWD 0x10000006 134 #define MUX_C_CLOSE_FWD 0x10000007 135 #define MUX_C_NEW_STDIO_FWD 0x10000008 136 #define MUX_C_STOP_LISTENING 0x10000009 137 #define MUX_S_OK 0x80000001 138 #define MUX_S_PERMISSION_DENIED 0x80000002 139 #define MUX_S_FAILURE 0x80000003 140 #define MUX_S_EXIT_MESSAGE 0x80000004 141 #define MUX_S_ALIVE 0x80000005 142 #define MUX_S_SESSION_OPENED 0x80000006 143 #define MUX_S_REMOTE_PORT 0x80000007 144 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 145 146 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 147 #define MUX_FWD_LOCAL 1 148 #define MUX_FWD_REMOTE 2 149 #define MUX_FWD_DYNAMIC 3 150 151 static void mux_session_confirm(int, int, void *); 152 static void mux_stdio_confirm(int, int, void *); 153 154 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 155 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 156 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 157 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 158 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 159 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 160 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 161 static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *); 162 163 static const struct { 164 u_int type; 165 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 166 } mux_master_handlers[] = { 167 { MUX_MSG_HELLO, process_mux_master_hello }, 168 { MUX_C_NEW_SESSION, process_mux_new_session }, 169 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 170 { MUX_C_TERMINATE, process_mux_terminate }, 171 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 172 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 173 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 174 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 175 { 0, NULL } 176 }; 177 178 /* Cleanup callback fired on closure of mux slave _session_ channel */ 179 /* ARGSUSED */ 180 static void 181 mux_master_session_cleanup_cb(int cid, void *unused) 182 { 183 Channel *cc, *c = channel_by_id(cid); 184 185 debug3("%s: entering for channel %d", __func__, cid); 186 if (c == NULL) 187 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 188 if (c->ctl_chan != -1) { 189 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 190 fatal("%s: channel %d missing control channel %d", 191 __func__, c->self, c->ctl_chan); 192 c->ctl_chan = -1; 193 cc->remote_id = -1; 194 chan_rcvd_oclose(cc); 195 } 196 channel_cancel_cleanup(c->self); 197 } 198 199 /* Cleanup callback fired on closure of mux slave _control_ channel */ 200 /* ARGSUSED */ 201 static void 202 mux_master_control_cleanup_cb(int cid, void *unused) 203 { 204 Channel *sc, *c = channel_by_id(cid); 205 206 debug3("%s: entering for channel %d", __func__, cid); 207 if (c == NULL) 208 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 209 if (c->remote_id != -1) { 210 if ((sc = channel_by_id(c->remote_id)) == NULL) 211 fatal("%s: channel %d missing session channel %d", 212 __func__, c->self, c->remote_id); 213 c->remote_id = -1; 214 sc->ctl_chan = -1; 215 if (sc->type != SSH_CHANNEL_OPEN && 216 sc->type != SSH_CHANNEL_OPENING) { 217 debug2("%s: channel %d: not open", __func__, sc->self); 218 chan_mark_dead(sc); 219 } else { 220 if (sc->istate == CHAN_INPUT_OPEN) 221 chan_read_failed(sc); 222 if (sc->ostate == CHAN_OUTPUT_OPEN) 223 chan_write_failed(sc); 224 } 225 } 226 channel_cancel_cleanup(c->self); 227 } 228 229 /* Check mux client environment variables before passing them to mux master. */ 230 static int 231 env_permitted(char *env) 232 { 233 int i, ret; 234 char name[1024], *cp; 235 236 if ((cp = strchr(env, '=')) == NULL || cp == env) 237 return 0; 238 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 239 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 240 error("env_permitted: name '%.100s...' too long", env); 241 return 0; 242 } 243 244 for (i = 0; i < options.num_send_env; i++) 245 if (match_pattern(name, options.send_env[i])) 246 return 1; 247 248 return 0; 249 } 250 251 /* Mux master protocol message handlers */ 252 253 static int 254 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 255 { 256 u_int ver; 257 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 258 259 if (state == NULL) 260 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 261 if (state->hello_rcvd) { 262 error("%s: HELLO received twice", __func__); 263 return -1; 264 } 265 if (buffer_get_int_ret(&ver, m) != 0) { 266 malf: 267 error("%s: malformed message", __func__); 268 return -1; 269 } 270 if (ver != SSHMUX_VER) { 271 error("Unsupported multiplexing protocol version %d " 272 "(expected %d)", ver, SSHMUX_VER); 273 return -1; 274 } 275 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 276 277 /* No extensions are presently defined */ 278 while (buffer_len(m) > 0) { 279 char *name = buffer_get_string_ret(m, NULL); 280 char *value = buffer_get_string_ret(m, NULL); 281 282 if (name == NULL || value == NULL) { 283 free(name); 284 free(value); 285 goto malf; 286 } 287 debug2("Unrecognised slave extension \"%s\"", name); 288 free(name); 289 free(value); 290 } 291 state->hello_rcvd = 1; 292 return 0; 293 } 294 295 static int 296 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 297 { 298 Channel *nc; 299 struct mux_session_confirm_ctx *cctx; 300 char *reserved, *cmd, *cp; 301 u_int i, j, len, env_len, escape_char, window, packetmax; 302 int new_fd[3]; 303 304 /* Reply for SSHMUX_COMMAND_OPEN */ 305 cctx = xcalloc(1, sizeof(*cctx)); 306 cctx->term = NULL; 307 cctx->rid = rid; 308 cmd = reserved = NULL; 309 cctx->env = NULL; 310 env_len = 0; 311 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 312 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 313 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 314 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 315 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 316 buffer_get_int_ret(&escape_char, m) != 0 || 317 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 318 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 319 malf: 320 free(cmd); 321 free(reserved); 322 for (j = 0; j < env_len; j++) 323 free(cctx->env[j]); 324 free(cctx->env); 325 free(cctx->term); 326 free(cctx); 327 error("%s: malformed message", __func__); 328 return -1; 329 } 330 free(reserved); 331 reserved = NULL; 332 333 while (buffer_len(m) > 0) { 334 #define MUX_MAX_ENV_VARS 4096 335 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 336 goto malf; 337 if (!env_permitted(cp)) { 338 free(cp); 339 continue; 340 } 341 cctx->env = xrealloc(cctx->env, env_len + 2, 342 sizeof(*cctx->env)); 343 cctx->env[env_len++] = cp; 344 cctx->env[env_len] = NULL; 345 if (env_len > MUX_MAX_ENV_VARS) { 346 error(">%d environment variables received, ignoring " 347 "additional", MUX_MAX_ENV_VARS); 348 break; 349 } 350 } 351 352 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 353 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 354 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 355 cctx->want_subsys, cctx->term, cmd, env_len); 356 357 buffer_init(&cctx->cmd); 358 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 359 free(cmd); 360 cmd = NULL; 361 362 /* Gather fds from client */ 363 for(i = 0; i < 3; i++) { 364 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 365 error("%s: failed to receive fd %d from slave", 366 __func__, i); 367 for (j = 0; j < i; j++) 368 close(new_fd[j]); 369 for (j = 0; j < env_len; j++) 370 free(cctx->env[j]); 371 free(cctx->env); 372 free(cctx->term); 373 buffer_free(&cctx->cmd); 374 free(cctx); 375 376 /* prepare reply */ 377 buffer_put_int(r, MUX_S_FAILURE); 378 buffer_put_int(r, rid); 379 buffer_put_cstring(r, 380 "did not receive file descriptors"); 381 return -1; 382 } 383 } 384 385 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 386 new_fd[0], new_fd[1], new_fd[2]); 387 388 /* XXX support multiple child sessions in future */ 389 if (c->remote_id != -1) { 390 debug2("%s: session already open", __func__); 391 /* prepare reply */ 392 buffer_put_int(r, MUX_S_FAILURE); 393 buffer_put_int(r, rid); 394 buffer_put_cstring(r, "Multiple sessions not supported"); 395 cleanup: 396 close(new_fd[0]); 397 close(new_fd[1]); 398 close(new_fd[2]); 399 free(cctx->term); 400 if (env_len != 0) { 401 for (i = 0; i < env_len; i++) 402 free(cctx->env[i]); 403 free(cctx->env); 404 } 405 buffer_free(&cctx->cmd); 406 free(cctx); 407 return 0; 408 } 409 410 if (options.control_master == SSHCTL_MASTER_ASK || 411 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 412 if (!ask_permission("Allow shared connection to %s? ", host)) { 413 debug2("%s: session refused by user", __func__); 414 /* prepare reply */ 415 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 416 buffer_put_int(r, rid); 417 buffer_put_cstring(r, "Permission denied"); 418 goto cleanup; 419 } 420 } 421 422 /* Try to pick up ttymodes from client before it goes raw */ 423 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 424 error("%s: tcgetattr: %s", __func__, strerror(errno)); 425 426 /* enable nonblocking unless tty */ 427 if (!isatty(new_fd[0])) 428 set_nonblock(new_fd[0]); 429 if (!isatty(new_fd[1])) 430 set_nonblock(new_fd[1]); 431 if (!isatty(new_fd[2])) 432 set_nonblock(new_fd[2]); 433 434 window = CHAN_SES_WINDOW_DEFAULT; 435 packetmax = CHAN_SES_PACKET_DEFAULT; 436 if (cctx->want_tty) { 437 window >>= 1; 438 packetmax >>= 1; 439 } 440 441 nc = channel_new("session", SSH_CHANNEL_OPENING, 442 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 443 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 444 445 nc->ctl_chan = c->self; /* link session -> control channel */ 446 c->remote_id = nc->self; /* link control -> session channel */ 447 448 if (cctx->want_tty && escape_char != 0xffffffff) { 449 channel_register_filter(nc->self, 450 client_simple_escape_filter, NULL, 451 client_filter_cleanup, 452 client_new_escape_filter_ctx((int)escape_char)); 453 } 454 455 debug2("%s: channel_new: %d linked to control channel %d", 456 __func__, nc->self, nc->ctl_chan); 457 458 channel_send_open(nc->self); 459 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 460 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 461 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 462 463 /* reply is deferred, sent by mux_session_confirm */ 464 return 0; 465 } 466 467 static int 468 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 469 { 470 debug2("%s: channel %d: alive check", __func__, c->self); 471 472 /* prepare reply */ 473 buffer_put_int(r, MUX_S_ALIVE); 474 buffer_put_int(r, rid); 475 buffer_put_int(r, (u_int)getpid()); 476 477 return 0; 478 } 479 480 static int 481 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 482 { 483 debug2("%s: channel %d: terminate request", __func__, c->self); 484 485 if (options.control_master == SSHCTL_MASTER_ASK || 486 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 487 if (!ask_permission("Terminate shared connection to %s? ", 488 host)) { 489 debug2("%s: termination refused by user", __func__); 490 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 491 buffer_put_int(r, rid); 492 buffer_put_cstring(r, "Permission denied"); 493 return 0; 494 } 495 } 496 497 quit_pending = 1; 498 buffer_put_int(r, MUX_S_OK); 499 buffer_put_int(r, rid); 500 /* XXX exit happens too soon - message never makes it to client */ 501 return 0; 502 } 503 504 static char * 505 format_forward(u_int ftype, struct Forward *fwd) 506 { 507 char *ret; 508 509 switch (ftype) { 510 case MUX_FWD_LOCAL: 511 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 512 (fwd->listen_path != NULL) ? fwd->listen_path : 513 (fwd->listen_host == NULL) ? 514 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 515 fwd->listen_host, fwd->listen_port, 516 (fwd->connect_path != NULL) ? fwd->connect_path : 517 fwd->connect_host, fwd->connect_port); 518 break; 519 case MUX_FWD_DYNAMIC: 520 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 521 (fwd->listen_host == NULL) ? 522 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 523 fwd->listen_host, fwd->listen_port); 524 break; 525 case MUX_FWD_REMOTE: 526 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 527 (fwd->listen_path != NULL) ? fwd->listen_path : 528 (fwd->listen_host == NULL) ? 529 "LOCALHOST" : fwd->listen_host, 530 fwd->listen_port, 531 (fwd->connect_path != NULL) ? fwd->connect_path : 532 fwd->connect_host, fwd->connect_port); 533 break; 534 default: 535 fatal("%s: unknown forward type %u", __func__, ftype); 536 } 537 return ret; 538 } 539 540 static int 541 compare_host(const char *a, const char *b) 542 { 543 if (a == NULL && b == NULL) 544 return 1; 545 if (a == NULL || b == NULL) 546 return 0; 547 return strcmp(a, b) == 0; 548 } 549 550 static int 551 compare_forward(struct Forward *a, struct Forward *b) 552 { 553 if (!compare_host(a->listen_host, b->listen_host)) 554 return 0; 555 if (!compare_host(a->listen_path, b->listen_path)) 556 return 0; 557 if (a->listen_port != b->listen_port) 558 return 0; 559 if (!compare_host(a->connect_host, b->connect_host)) 560 return 0; 561 if (!compare_host(a->connect_path, b->connect_path)) 562 return 0; 563 if (a->connect_port != b->connect_port) 564 return 0; 565 566 return 1; 567 } 568 569 static void 570 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 571 { 572 struct mux_channel_confirm_ctx *fctx = ctxt; 573 char *failmsg = NULL; 574 struct Forward *rfwd; 575 Channel *c; 576 Buffer out; 577 578 if ((c = channel_by_id(fctx->cid)) == NULL) { 579 /* no channel for reply */ 580 error("%s: unknown channel", __func__); 581 return; 582 } 583 buffer_init(&out); 584 if (fctx->fid >= options.num_remote_forwards) { 585 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 586 goto fail; 587 } 588 rfwd = &options.remote_forwards[fctx->fid]; 589 debug("%s: %s for: listen %d, connect %s:%d", __func__, 590 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 591 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 592 rfwd->connect_host, rfwd->connect_port); 593 if (type == SSH2_MSG_REQUEST_SUCCESS) { 594 if (rfwd->listen_port == 0) { 595 rfwd->allocated_port = packet_get_int(); 596 logit("Allocated port %u for mux remote forward" 597 " to %s:%d", rfwd->allocated_port, 598 rfwd->connect_host, rfwd->connect_port); 599 buffer_put_int(&out, MUX_S_REMOTE_PORT); 600 buffer_put_int(&out, fctx->rid); 601 buffer_put_int(&out, rfwd->allocated_port); 602 channel_update_permitted_opens(rfwd->handle, 603 rfwd->allocated_port); 604 } else { 605 buffer_put_int(&out, MUX_S_OK); 606 buffer_put_int(&out, fctx->rid); 607 } 608 goto out; 609 } else { 610 if (rfwd->listen_port == 0) 611 channel_update_permitted_opens(rfwd->handle, -1); 612 if (rfwd->listen_path != NULL) 613 xasprintf(&failmsg, "remote port forwarding failed for " 614 "listen path %s", rfwd->listen_path); 615 else 616 xasprintf(&failmsg, "remote port forwarding failed for " 617 "listen port %d", rfwd->listen_port); 618 } 619 fail: 620 error("%s: %s", __func__, failmsg); 621 buffer_put_int(&out, MUX_S_FAILURE); 622 buffer_put_int(&out, fctx->rid); 623 buffer_put_cstring(&out, failmsg); 624 free(failmsg); 625 out: 626 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 627 buffer_free(&out); 628 if (c->mux_pause <= 0) 629 fatal("%s: mux_pause %d", __func__, c->mux_pause); 630 c->mux_pause = 0; /* start processing messages again */ 631 } 632 633 static int 634 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 635 { 636 struct Forward fwd; 637 char *fwd_desc = NULL; 638 char *listen_addr, *connect_addr; 639 u_int ftype; 640 u_int lport, cport; 641 int i, ret = 0, freefwd = 1; 642 643 /* XXX - lport/cport check redundant */ 644 if (buffer_get_int_ret(&ftype, m) != 0 || 645 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 646 buffer_get_int_ret(&lport, m) != 0 || 647 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 648 buffer_get_int_ret(&cport, m) != 0 || 649 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 650 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 651 error("%s: malformed message", __func__); 652 ret = -1; 653 goto out; 654 } 655 if (*listen_addr == '\0') { 656 free(listen_addr); 657 listen_addr = NULL; 658 } 659 if (*connect_addr == '\0') { 660 free(connect_addr); 661 connect_addr = NULL; 662 } 663 664 memset(&fwd, 0, sizeof(fwd)); 665 fwd.listen_port = lport; 666 if (fwd.listen_port == PORT_STREAMLOCAL) 667 fwd.listen_path = listen_addr; 668 else 669 fwd.listen_host = listen_addr; 670 fwd.connect_port = cport; 671 if (fwd.connect_port == PORT_STREAMLOCAL) 672 fwd.connect_path = connect_addr; 673 else 674 fwd.connect_host = connect_addr; 675 676 debug2("%s: channel %d: request %s", __func__, c->self, 677 (fwd_desc = format_forward(ftype, &fwd))); 678 679 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 680 ftype != MUX_FWD_DYNAMIC) { 681 logit("%s: invalid forwarding type %u", __func__, ftype); 682 invalid: 683 free(listen_addr); 684 free(connect_addr); 685 buffer_put_int(r, MUX_S_FAILURE); 686 buffer_put_int(r, rid); 687 buffer_put_cstring(r, "Invalid forwarding request"); 688 return 0; 689 } 690 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 691 logit("%s: streamlocal and dynamic forwards " 692 "are mutually exclusive", __func__); 693 goto invalid; 694 } 695 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 696 logit("%s: invalid listen port %u", __func__, 697 fwd.listen_port); 698 goto invalid; 699 } 700 if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) 701 || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 702 logit("%s: invalid connect port %u", __func__, 703 fwd.connect_port); 704 goto invalid; 705 } 706 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { 707 logit("%s: missing connect host", __func__); 708 goto invalid; 709 } 710 711 /* Skip forwards that have already been requested */ 712 switch (ftype) { 713 case MUX_FWD_LOCAL: 714 case MUX_FWD_DYNAMIC: 715 for (i = 0; i < options.num_local_forwards; i++) { 716 if (compare_forward(&fwd, 717 options.local_forwards + i)) { 718 exists: 719 debug2("%s: found existing forwarding", 720 __func__); 721 buffer_put_int(r, MUX_S_OK); 722 buffer_put_int(r, rid); 723 goto out; 724 } 725 } 726 break; 727 case MUX_FWD_REMOTE: 728 for (i = 0; i < options.num_remote_forwards; i++) { 729 if (compare_forward(&fwd, 730 options.remote_forwards + i)) { 731 if (fwd.listen_port != 0) 732 goto exists; 733 debug2("%s: found allocated port", 734 __func__); 735 buffer_put_int(r, MUX_S_REMOTE_PORT); 736 buffer_put_int(r, rid); 737 buffer_put_int(r, 738 options.remote_forwards[i].allocated_port); 739 goto out; 740 } 741 } 742 break; 743 } 744 745 if (options.control_master == SSHCTL_MASTER_ASK || 746 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 747 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 748 debug2("%s: forwarding refused by user", __func__); 749 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 750 buffer_put_int(r, rid); 751 buffer_put_cstring(r, "Permission denied"); 752 goto out; 753 } 754 } 755 756 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 757 if (!channel_setup_local_fwd_listener(&fwd, 758 &options.fwd_opts)) { 759 fail: 760 logit("slave-requested %s failed", fwd_desc); 761 buffer_put_int(r, MUX_S_FAILURE); 762 buffer_put_int(r, rid); 763 buffer_put_cstring(r, "Port forwarding failed"); 764 goto out; 765 } 766 add_local_forward(&options, &fwd); 767 freefwd = 0; 768 } else { 769 struct mux_channel_confirm_ctx *fctx; 770 771 fwd.handle = channel_request_remote_forwarding(&fwd); 772 if (fwd.handle < 0) 773 goto fail; 774 add_remote_forward(&options, &fwd); 775 fctx = xcalloc(1, sizeof(*fctx)); 776 fctx->cid = c->self; 777 fctx->rid = rid; 778 fctx->fid = options.num_remote_forwards - 1; 779 client_register_global_confirm(mux_confirm_remote_forward, 780 fctx); 781 freefwd = 0; 782 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 783 /* delayed reply in mux_confirm_remote_forward */ 784 goto out; 785 } 786 buffer_put_int(r, MUX_S_OK); 787 buffer_put_int(r, rid); 788 out: 789 free(fwd_desc); 790 if (freefwd) { 791 free(fwd.listen_host); 792 free(fwd.listen_path); 793 free(fwd.connect_host); 794 free(fwd.connect_path); 795 } 796 return ret; 797 } 798 799 static int 800 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 801 { 802 struct Forward fwd, *found_fwd; 803 char *fwd_desc = NULL; 804 const char *error_reason = NULL; 805 char *listen_addr = NULL, *connect_addr = NULL; 806 u_int ftype; 807 int i, ret = 0; 808 u_int lport, cport; 809 810 if (buffer_get_int_ret(&ftype, m) != 0 || 811 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 812 buffer_get_int_ret(&lport, m) != 0 || 813 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 814 buffer_get_int_ret(&cport, m) != 0 || 815 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 816 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 817 error("%s: malformed message", __func__); 818 ret = -1; 819 goto out; 820 } 821 822 if (*listen_addr == '\0') { 823 free(listen_addr); 824 listen_addr = NULL; 825 } 826 if (*connect_addr == '\0') { 827 free(connect_addr); 828 connect_addr = NULL; 829 } 830 831 memset(&fwd, 0, sizeof(fwd)); 832 fwd.listen_port = lport; 833 if (fwd.listen_port == PORT_STREAMLOCAL) 834 fwd.listen_path = listen_addr; 835 else 836 fwd.listen_host = listen_addr; 837 fwd.connect_port = cport; 838 if (fwd.connect_port == PORT_STREAMLOCAL) 839 fwd.connect_path = connect_addr; 840 else 841 fwd.connect_host = connect_addr; 842 843 debug2("%s: channel %d: request cancel %s", __func__, c->self, 844 (fwd_desc = format_forward(ftype, &fwd))); 845 846 /* make sure this has been requested */ 847 found_fwd = NULL; 848 switch (ftype) { 849 case MUX_FWD_LOCAL: 850 case MUX_FWD_DYNAMIC: 851 for (i = 0; i < options.num_local_forwards; i++) { 852 if (compare_forward(&fwd, 853 options.local_forwards + i)) { 854 found_fwd = options.local_forwards + i; 855 break; 856 } 857 } 858 break; 859 case MUX_FWD_REMOTE: 860 for (i = 0; i < options.num_remote_forwards; i++) { 861 if (compare_forward(&fwd, 862 options.remote_forwards + i)) { 863 found_fwd = options.remote_forwards + i; 864 break; 865 } 866 } 867 break; 868 } 869 870 if (found_fwd == NULL) 871 error_reason = "port not forwarded"; 872 else if (ftype == MUX_FWD_REMOTE) { 873 /* 874 * This shouldn't fail unless we confused the host/port 875 * between options.remote_forwards and permitted_opens. 876 * However, for dynamic allocated listen ports we need 877 * to use the actual listen port. 878 */ 879 if (channel_request_rforward_cancel(found_fwd) == -1) 880 error_reason = "port not in permitted opens"; 881 } else { /* local and dynamic forwards */ 882 /* Ditto */ 883 if (channel_cancel_lport_listener(&fwd, fwd.connect_port, 884 &options.fwd_opts) == -1) 885 error_reason = "port not found"; 886 } 887 888 if (error_reason == NULL) { 889 buffer_put_int(r, MUX_S_OK); 890 buffer_put_int(r, rid); 891 892 free(found_fwd->listen_host); 893 free(found_fwd->listen_path); 894 free(found_fwd->connect_host); 895 free(found_fwd->connect_path); 896 found_fwd->listen_host = found_fwd->connect_host = NULL; 897 found_fwd->listen_path = found_fwd->connect_path = NULL; 898 found_fwd->listen_port = found_fwd->connect_port = 0; 899 } else { 900 buffer_put_int(r, MUX_S_FAILURE); 901 buffer_put_int(r, rid); 902 buffer_put_cstring(r, error_reason); 903 } 904 out: 905 free(fwd_desc); 906 free(listen_addr); 907 free(connect_addr); 908 909 return ret; 910 } 911 912 static int 913 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 914 { 915 Channel *nc; 916 char *reserved, *chost; 917 u_int cport, i, j; 918 int new_fd[2]; 919 struct mux_stdio_confirm_ctx *cctx; 920 921 chost = reserved = NULL; 922 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 923 (chost = buffer_get_string_ret(m, NULL)) == NULL || 924 buffer_get_int_ret(&cport, m) != 0) { 925 free(reserved); 926 free(chost); 927 error("%s: malformed message", __func__); 928 return -1; 929 } 930 free(reserved); 931 932 debug2("%s: channel %d: request stdio fwd to %s:%u", 933 __func__, c->self, chost, cport); 934 935 /* Gather fds from client */ 936 for(i = 0; i < 2; i++) { 937 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 938 error("%s: failed to receive fd %d from slave", 939 __func__, i); 940 for (j = 0; j < i; j++) 941 close(new_fd[j]); 942 free(chost); 943 944 /* prepare reply */ 945 buffer_put_int(r, MUX_S_FAILURE); 946 buffer_put_int(r, rid); 947 buffer_put_cstring(r, 948 "did not receive file descriptors"); 949 return -1; 950 } 951 } 952 953 debug3("%s: got fds stdin %d, stdout %d", __func__, 954 new_fd[0], new_fd[1]); 955 956 /* XXX support multiple child sessions in future */ 957 if (c->remote_id != -1) { 958 debug2("%s: session already open", __func__); 959 /* prepare reply */ 960 buffer_put_int(r, MUX_S_FAILURE); 961 buffer_put_int(r, rid); 962 buffer_put_cstring(r, "Multiple sessions not supported"); 963 cleanup: 964 close(new_fd[0]); 965 close(new_fd[1]); 966 free(chost); 967 return 0; 968 } 969 970 if (options.control_master == SSHCTL_MASTER_ASK || 971 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 972 if (!ask_permission("Allow forward to %s:%u? ", 973 chost, cport)) { 974 debug2("%s: stdio fwd refused by user", __func__); 975 /* prepare reply */ 976 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 977 buffer_put_int(r, rid); 978 buffer_put_cstring(r, "Permission denied"); 979 goto cleanup; 980 } 981 } 982 983 /* enable nonblocking unless tty */ 984 if (!isatty(new_fd[0])) 985 set_nonblock(new_fd[0]); 986 if (!isatty(new_fd[1])) 987 set_nonblock(new_fd[1]); 988 989 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 990 991 nc->ctl_chan = c->self; /* link session -> control channel */ 992 c->remote_id = nc->self; /* link control -> session channel */ 993 994 debug2("%s: channel_new: %d linked to control channel %d", 995 __func__, nc->self, nc->ctl_chan); 996 997 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 998 999 cctx = xcalloc(1, sizeof(*cctx)); 1000 cctx->rid = rid; 1001 channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx); 1002 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1003 1004 /* reply is deferred, sent by mux_session_confirm */ 1005 return 0; 1006 } 1007 1008 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1009 static void 1010 mux_stdio_confirm(int id, int success, void *arg) 1011 { 1012 struct mux_stdio_confirm_ctx *cctx = arg; 1013 Channel *c, *cc; 1014 Buffer reply; 1015 1016 if (cctx == NULL) 1017 fatal("%s: cctx == NULL", __func__); 1018 if ((c = channel_by_id(id)) == NULL) 1019 fatal("%s: no channel for id %d", __func__, id); 1020 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1021 fatal("%s: channel %d lacks control channel %d", __func__, 1022 id, c->ctl_chan); 1023 1024 if (!success) { 1025 debug3("%s: sending failure reply", __func__); 1026 /* prepare reply */ 1027 buffer_init(&reply); 1028 buffer_put_int(&reply, MUX_S_FAILURE); 1029 buffer_put_int(&reply, cctx->rid); 1030 buffer_put_cstring(&reply, "Session open refused by peer"); 1031 goto done; 1032 } 1033 1034 debug3("%s: sending success reply", __func__); 1035 /* prepare reply */ 1036 buffer_init(&reply); 1037 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1038 buffer_put_int(&reply, cctx->rid); 1039 buffer_put_int(&reply, c->self); 1040 1041 done: 1042 /* Send reply */ 1043 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1044 buffer_free(&reply); 1045 1046 if (cc->mux_pause <= 0) 1047 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1048 cc->mux_pause = 0; /* start processing messages again */ 1049 c->open_confirm_ctx = NULL; 1050 free(cctx); 1051 } 1052 1053 static int 1054 process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) 1055 { 1056 debug("%s: channel %d: stop listening", __func__, c->self); 1057 1058 if (options.control_master == SSHCTL_MASTER_ASK || 1059 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1060 if (!ask_permission("Disable further multiplexing on shared " 1061 "connection to %s? ", host)) { 1062 debug2("%s: stop listen refused by user", __func__); 1063 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1064 buffer_put_int(r, rid); 1065 buffer_put_cstring(r, "Permission denied"); 1066 return 0; 1067 } 1068 } 1069 1070 if (mux_listener_channel != NULL) { 1071 channel_free(mux_listener_channel); 1072 client_stop_mux(); 1073 free(options.control_path); 1074 options.control_path = NULL; 1075 mux_listener_channel = NULL; 1076 muxserver_sock = -1; 1077 } 1078 1079 /* prepare reply */ 1080 buffer_put_int(r, MUX_S_OK); 1081 buffer_put_int(r, rid); 1082 1083 return 0; 1084 } 1085 1086 /* Channel callbacks fired on read/write from mux slave fd */ 1087 static int 1088 mux_master_read_cb(Channel *c) 1089 { 1090 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1091 Buffer in, out; 1092 const u_char *ptr; 1093 u_int type, rid, have, i; 1094 int ret = -1; 1095 1096 /* Setup ctx and */ 1097 if (c->mux_ctx == NULL) { 1098 state = xcalloc(1, sizeof(*state)); 1099 c->mux_ctx = state; 1100 channel_register_cleanup(c->self, 1101 mux_master_control_cleanup_cb, 0); 1102 1103 /* Send hello */ 1104 buffer_init(&out); 1105 buffer_put_int(&out, MUX_MSG_HELLO); 1106 buffer_put_int(&out, SSHMUX_VER); 1107 /* no extensions */ 1108 buffer_put_string(&c->output, buffer_ptr(&out), 1109 buffer_len(&out)); 1110 buffer_free(&out); 1111 debug3("%s: channel %d: hello sent", __func__, c->self); 1112 return 0; 1113 } 1114 1115 buffer_init(&in); 1116 buffer_init(&out); 1117 1118 /* Channel code ensures that we receive whole packets */ 1119 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 1120 malf: 1121 error("%s: malformed message", __func__); 1122 goto out; 1123 } 1124 buffer_append(&in, ptr, have); 1125 1126 if (buffer_get_int_ret(&type, &in) != 0) 1127 goto malf; 1128 debug3("%s: channel %d packet type 0x%08x len %u", 1129 __func__, c->self, type, buffer_len(&in)); 1130 1131 if (type == MUX_MSG_HELLO) 1132 rid = 0; 1133 else { 1134 if (!state->hello_rcvd) { 1135 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1136 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1137 goto out; 1138 } 1139 if (buffer_get_int_ret(&rid, &in) != 0) 1140 goto malf; 1141 } 1142 1143 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1144 if (type == mux_master_handlers[i].type) { 1145 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 1146 break; 1147 } 1148 } 1149 if (mux_master_handlers[i].handler == NULL) { 1150 error("%s: unsupported mux message 0x%08x", __func__, type); 1151 buffer_put_int(&out, MUX_S_FAILURE); 1152 buffer_put_int(&out, rid); 1153 buffer_put_cstring(&out, "unsupported request"); 1154 ret = 0; 1155 } 1156 /* Enqueue reply packet */ 1157 if (buffer_len(&out) != 0) { 1158 buffer_put_string(&c->output, buffer_ptr(&out), 1159 buffer_len(&out)); 1160 } 1161 out: 1162 buffer_free(&in); 1163 buffer_free(&out); 1164 return ret; 1165 } 1166 1167 void 1168 mux_exit_message(Channel *c, int exitval) 1169 { 1170 Buffer m; 1171 Channel *mux_chan; 1172 1173 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1174 exitval); 1175 1176 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1177 fatal("%s: channel %d missing mux channel %d", 1178 __func__, c->self, c->ctl_chan); 1179 1180 /* Append exit message packet to control socket output queue */ 1181 buffer_init(&m); 1182 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1183 buffer_put_int(&m, c->self); 1184 buffer_put_int(&m, exitval); 1185 1186 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1187 buffer_free(&m); 1188 } 1189 1190 void 1191 mux_tty_alloc_failed(Channel *c) 1192 { 1193 Buffer m; 1194 Channel *mux_chan; 1195 1196 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1197 1198 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1199 fatal("%s: channel %d missing mux channel %d", 1200 __func__, c->self, c->ctl_chan); 1201 1202 /* Append exit message packet to control socket output queue */ 1203 buffer_init(&m); 1204 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1205 buffer_put_int(&m, c->self); 1206 1207 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1208 buffer_free(&m); 1209 } 1210 1211 /* Prepare a mux master to listen on a Unix domain socket. */ 1212 void 1213 muxserver_listen(void) 1214 { 1215 mode_t old_umask; 1216 char *orig_control_path = options.control_path; 1217 char rbuf[16+1]; 1218 u_int i, r; 1219 int oerrno; 1220 1221 if (options.control_path == NULL || 1222 options.control_master == SSHCTL_MASTER_NO) 1223 return; 1224 1225 debug("setting up multiplex master socket"); 1226 1227 /* 1228 * Use a temporary path before listen so we can pseudo-atomically 1229 * establish the listening socket in its final location to avoid 1230 * other processes racing in between bind() and listen() and hitting 1231 * an unready socket. 1232 */ 1233 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1234 r = arc4random_uniform(26+26+10); 1235 rbuf[i] = (r < 26) ? 'a' + r : 1236 (r < 26*2) ? 'A' + r - 26 : 1237 '0' + r - 26 - 26; 1238 } 1239 rbuf[sizeof(rbuf) - 1] = '\0'; 1240 options.control_path = NULL; 1241 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1242 debug3("%s: temporary control path %s", __func__, options.control_path); 1243 1244 old_umask = umask(0177); 1245 muxserver_sock = unix_listener(options.control_path, 64, 0); 1246 oerrno = errno; 1247 umask(old_umask); 1248 if (muxserver_sock < 0) { 1249 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1250 error("ControlSocket %s already exists, " 1251 "disabling multiplexing", options.control_path); 1252 disable_mux_master: 1253 if (muxserver_sock != -1) { 1254 close(muxserver_sock); 1255 muxserver_sock = -1; 1256 } 1257 free(orig_control_path); 1258 free(options.control_path); 1259 options.control_path = NULL; 1260 options.control_master = SSHCTL_MASTER_NO; 1261 return; 1262 } else { 1263 /* unix_listener() logs the error */ 1264 cleanup_exit(255); 1265 } 1266 } 1267 1268 /* Now atomically "move" the mux socket into position */ 1269 if (link(options.control_path, orig_control_path) != 0) { 1270 if (errno != EEXIST) { 1271 fatal("%s: link mux listener %s => %s: %s", __func__, 1272 options.control_path, orig_control_path, 1273 strerror(errno)); 1274 } 1275 error("ControlSocket %s already exists, disabling multiplexing", 1276 orig_control_path); 1277 unlink(options.control_path); 1278 goto disable_mux_master; 1279 } 1280 unlink(options.control_path); 1281 free(options.control_path); 1282 options.control_path = orig_control_path; 1283 1284 set_nonblock(muxserver_sock); 1285 1286 mux_listener_channel = channel_new("mux listener", 1287 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1288 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1289 0, options.control_path, 1); 1290 mux_listener_channel->mux_rcb = mux_master_read_cb; 1291 debug3("%s: mux listener channel %d fd %d", __func__, 1292 mux_listener_channel->self, mux_listener_channel->sock); 1293 } 1294 1295 /* Callback on open confirmation in mux master for a mux client session. */ 1296 static void 1297 mux_session_confirm(int id, int success, void *arg) 1298 { 1299 struct mux_session_confirm_ctx *cctx = arg; 1300 const char *display; 1301 Channel *c, *cc; 1302 int i; 1303 Buffer reply; 1304 1305 if (cctx == NULL) 1306 fatal("%s: cctx == NULL", __func__); 1307 if ((c = channel_by_id(id)) == NULL) 1308 fatal("%s: no channel for id %d", __func__, id); 1309 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1310 fatal("%s: channel %d lacks control channel %d", __func__, 1311 id, c->ctl_chan); 1312 1313 if (!success) { 1314 debug3("%s: sending failure reply", __func__); 1315 /* prepare reply */ 1316 buffer_init(&reply); 1317 buffer_put_int(&reply, MUX_S_FAILURE); 1318 buffer_put_int(&reply, cctx->rid); 1319 buffer_put_cstring(&reply, "Session open refused by peer"); 1320 goto done; 1321 } 1322 1323 display = getenv("DISPLAY"); 1324 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1325 char *proto, *data; 1326 1327 /* Get reasonable local authentication information. */ 1328 client_x11_get_proto(display, options.xauth_location, 1329 options.forward_x11_trusted, options.forward_x11_timeout, 1330 &proto, &data); 1331 /* Request forwarding with authentication spoofing. */ 1332 debug("Requesting X11 forwarding with authentication " 1333 "spoofing."); 1334 x11_request_forwarding_with_spoofing(id, display, proto, 1335 data, 1); 1336 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); 1337 /* XXX exit_on_forward_failure */ 1338 } 1339 1340 if (cctx->want_agent_fwd && options.forward_agent) { 1341 debug("Requesting authentication agent forwarding."); 1342 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1343 packet_send(); 1344 } 1345 1346 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1347 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1348 1349 debug3("%s: sending success reply", __func__); 1350 /* prepare reply */ 1351 buffer_init(&reply); 1352 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1353 buffer_put_int(&reply, cctx->rid); 1354 buffer_put_int(&reply, c->self); 1355 1356 done: 1357 /* Send reply */ 1358 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1359 buffer_free(&reply); 1360 1361 if (cc->mux_pause <= 0) 1362 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1363 cc->mux_pause = 0; /* start processing messages again */ 1364 c->open_confirm_ctx = NULL; 1365 buffer_free(&cctx->cmd); 1366 free(cctx->term); 1367 if (cctx->env != NULL) { 1368 for (i = 0; cctx->env[i] != NULL; i++) 1369 free(cctx->env[i]); 1370 free(cctx->env); 1371 } 1372 free(cctx); 1373 } 1374 1375 /* ** Multiplexing client support */ 1376 1377 /* Exit signal handler */ 1378 static void 1379 control_client_sighandler(int signo) 1380 { 1381 muxclient_terminate = signo; 1382 } 1383 1384 /* 1385 * Relay signal handler - used to pass some signals from mux client to 1386 * mux master. 1387 */ 1388 static void 1389 control_client_sigrelay(int signo) 1390 { 1391 int save_errno = errno; 1392 1393 if (muxserver_pid > 1) 1394 kill(muxserver_pid, signo); 1395 1396 errno = save_errno; 1397 } 1398 1399 static int 1400 mux_client_read(int fd, Buffer *b, u_int need) 1401 { 1402 u_int have; 1403 ssize_t len; 1404 u_char *p; 1405 struct pollfd pfd; 1406 1407 pfd.fd = fd; 1408 pfd.events = POLLIN; 1409 p = buffer_append_space(b, need); 1410 for (have = 0; have < need; ) { 1411 if (muxclient_terminate) { 1412 errno = EINTR; 1413 return -1; 1414 } 1415 len = read(fd, p + have, need - have); 1416 if (len < 0) { 1417 switch (errno) { 1418 case EAGAIN: 1419 (void)poll(&pfd, 1, -1); 1420 /* FALLTHROUGH */ 1421 case EINTR: 1422 continue; 1423 default: 1424 return -1; 1425 } 1426 } 1427 if (len == 0) { 1428 errno = EPIPE; 1429 return -1; 1430 } 1431 have += (u_int)len; 1432 } 1433 return 0; 1434 } 1435 1436 static int 1437 mux_client_write_packet(int fd, Buffer *m) 1438 { 1439 Buffer queue; 1440 u_int have, need; 1441 int oerrno, len; 1442 u_char *ptr; 1443 struct pollfd pfd; 1444 1445 pfd.fd = fd; 1446 pfd.events = POLLOUT; 1447 buffer_init(&queue); 1448 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1449 1450 need = buffer_len(&queue); 1451 ptr = buffer_ptr(&queue); 1452 1453 for (have = 0; have < need; ) { 1454 if (muxclient_terminate) { 1455 buffer_free(&queue); 1456 errno = EINTR; 1457 return -1; 1458 } 1459 len = write(fd, ptr + have, need - have); 1460 if (len < 0) { 1461 switch (errno) { 1462 case EAGAIN: 1463 (void)poll(&pfd, 1, -1); 1464 /* FALLTHROUGH */ 1465 case EINTR: 1466 continue; 1467 default: 1468 oerrno = errno; 1469 buffer_free(&queue); 1470 errno = oerrno; 1471 return -1; 1472 } 1473 } 1474 if (len == 0) { 1475 buffer_free(&queue); 1476 errno = EPIPE; 1477 return -1; 1478 } 1479 have += (u_int)len; 1480 } 1481 buffer_free(&queue); 1482 return 0; 1483 } 1484 1485 static int 1486 mux_client_read_packet(int fd, Buffer *m) 1487 { 1488 Buffer queue; 1489 u_int need, have; 1490 const u_char *ptr; 1491 int oerrno; 1492 1493 buffer_init(&queue); 1494 if (mux_client_read(fd, &queue, 4) != 0) { 1495 if ((oerrno = errno) == EPIPE) 1496 debug3("%s: read header failed: %s", __func__, 1497 strerror(errno)); 1498 buffer_free(&queue); 1499 errno = oerrno; 1500 return -1; 1501 } 1502 need = get_u32(buffer_ptr(&queue)); 1503 if (mux_client_read(fd, &queue, need) != 0) { 1504 oerrno = errno; 1505 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1506 buffer_free(&queue); 1507 errno = oerrno; 1508 return -1; 1509 } 1510 ptr = buffer_get_string_ptr(&queue, &have); 1511 buffer_append(m, ptr, have); 1512 buffer_free(&queue); 1513 return 0; 1514 } 1515 1516 static int 1517 mux_client_hello_exchange(int fd) 1518 { 1519 Buffer m; 1520 u_int type, ver; 1521 1522 buffer_init(&m); 1523 buffer_put_int(&m, MUX_MSG_HELLO); 1524 buffer_put_int(&m, SSHMUX_VER); 1525 /* no extensions */ 1526 1527 if (mux_client_write_packet(fd, &m) != 0) 1528 fatal("%s: write packet: %s", __func__, strerror(errno)); 1529 1530 buffer_clear(&m); 1531 1532 /* Read their HELLO */ 1533 if (mux_client_read_packet(fd, &m) != 0) { 1534 buffer_free(&m); 1535 return -1; 1536 } 1537 1538 type = buffer_get_int(&m); 1539 if (type != MUX_MSG_HELLO) 1540 fatal("%s: expected HELLO (%u) received %u", 1541 __func__, MUX_MSG_HELLO, type); 1542 ver = buffer_get_int(&m); 1543 if (ver != SSHMUX_VER) 1544 fatal("Unsupported multiplexing protocol version %d " 1545 "(expected %d)", ver, SSHMUX_VER); 1546 debug2("%s: master version %u", __func__, ver); 1547 /* No extensions are presently defined */ 1548 while (buffer_len(&m) > 0) { 1549 char *name = buffer_get_string(&m, NULL); 1550 char *value = buffer_get_string(&m, NULL); 1551 1552 debug2("Unrecognised master extension \"%s\"", name); 1553 free(name); 1554 free(value); 1555 } 1556 buffer_free(&m); 1557 return 0; 1558 } 1559 1560 static u_int 1561 mux_client_request_alive(int fd) 1562 { 1563 Buffer m; 1564 char *e; 1565 u_int pid, type, rid; 1566 1567 debug3("%s: entering", __func__); 1568 1569 buffer_init(&m); 1570 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1571 buffer_put_int(&m, muxclient_request_id); 1572 1573 if (mux_client_write_packet(fd, &m) != 0) 1574 fatal("%s: write packet: %s", __func__, strerror(errno)); 1575 1576 buffer_clear(&m); 1577 1578 /* Read their reply */ 1579 if (mux_client_read_packet(fd, &m) != 0) { 1580 buffer_free(&m); 1581 return 0; 1582 } 1583 1584 type = buffer_get_int(&m); 1585 if (type != MUX_S_ALIVE) { 1586 e = buffer_get_string(&m, NULL); 1587 fatal("%s: master returned error: %s", __func__, e); 1588 } 1589 1590 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1591 fatal("%s: out of sequence reply: my id %u theirs %u", 1592 __func__, muxclient_request_id, rid); 1593 pid = buffer_get_int(&m); 1594 buffer_free(&m); 1595 1596 debug3("%s: done pid = %u", __func__, pid); 1597 1598 muxclient_request_id++; 1599 1600 return pid; 1601 } 1602 1603 static void 1604 mux_client_request_terminate(int fd) 1605 { 1606 Buffer m; 1607 char *e; 1608 u_int type, rid; 1609 1610 debug3("%s: entering", __func__); 1611 1612 buffer_init(&m); 1613 buffer_put_int(&m, MUX_C_TERMINATE); 1614 buffer_put_int(&m, muxclient_request_id); 1615 1616 if (mux_client_write_packet(fd, &m) != 0) 1617 fatal("%s: write packet: %s", __func__, strerror(errno)); 1618 1619 buffer_clear(&m); 1620 1621 /* Read their reply */ 1622 if (mux_client_read_packet(fd, &m) != 0) { 1623 /* Remote end exited already */ 1624 if (errno == EPIPE) { 1625 buffer_free(&m); 1626 return; 1627 } 1628 fatal("%s: read from master failed: %s", 1629 __func__, strerror(errno)); 1630 } 1631 1632 type = buffer_get_int(&m); 1633 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1634 fatal("%s: out of sequence reply: my id %u theirs %u", 1635 __func__, muxclient_request_id, rid); 1636 switch (type) { 1637 case MUX_S_OK: 1638 break; 1639 case MUX_S_PERMISSION_DENIED: 1640 e = buffer_get_string(&m, NULL); 1641 fatal("Master refused termination request: %s", e); 1642 case MUX_S_FAILURE: 1643 e = buffer_get_string(&m, NULL); 1644 fatal("%s: termination request failed: %s", __func__, e); 1645 default: 1646 fatal("%s: unexpected response from master 0x%08x", 1647 __func__, type); 1648 } 1649 buffer_free(&m); 1650 muxclient_request_id++; 1651 } 1652 1653 static int 1654 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1655 { 1656 Buffer m; 1657 char *e, *fwd_desc; 1658 u_int type, rid; 1659 1660 fwd_desc = format_forward(ftype, fwd); 1661 debug("Requesting %s %s", 1662 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1663 free(fwd_desc); 1664 1665 buffer_init(&m); 1666 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1667 buffer_put_int(&m, muxclient_request_id); 1668 buffer_put_int(&m, ftype); 1669 if (fwd->listen_path != NULL) { 1670 buffer_put_cstring(&m, fwd->listen_path); 1671 } else { 1672 buffer_put_cstring(&m, 1673 fwd->listen_host == NULL ? "" : fwd->listen_host); 1674 } 1675 buffer_put_int(&m, fwd->listen_port); 1676 if (fwd->connect_path != NULL) { 1677 buffer_put_cstring(&m, fwd->connect_path); 1678 } else { 1679 buffer_put_cstring(&m, 1680 fwd->connect_host == NULL ? "" : fwd->connect_host); 1681 } 1682 buffer_put_int(&m, fwd->connect_port); 1683 1684 if (mux_client_write_packet(fd, &m) != 0) 1685 fatal("%s: write packet: %s", __func__, strerror(errno)); 1686 1687 buffer_clear(&m); 1688 1689 /* Read their reply */ 1690 if (mux_client_read_packet(fd, &m) != 0) { 1691 buffer_free(&m); 1692 return -1; 1693 } 1694 1695 type = buffer_get_int(&m); 1696 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1697 fatal("%s: out of sequence reply: my id %u theirs %u", 1698 __func__, muxclient_request_id, rid); 1699 switch (type) { 1700 case MUX_S_OK: 1701 break; 1702 case MUX_S_REMOTE_PORT: 1703 if (cancel_flag) 1704 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1705 fwd->allocated_port = buffer_get_int(&m); 1706 logit("Allocated port %u for remote forward to %s:%d", 1707 fwd->allocated_port, 1708 fwd->connect_host ? fwd->connect_host : "", 1709 fwd->connect_port); 1710 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1711 fprintf(stdout, "%u\n", fwd->allocated_port); 1712 break; 1713 case MUX_S_PERMISSION_DENIED: 1714 e = buffer_get_string(&m, NULL); 1715 buffer_free(&m); 1716 error("Master refused forwarding request: %s", e); 1717 return -1; 1718 case MUX_S_FAILURE: 1719 e = buffer_get_string(&m, NULL); 1720 buffer_free(&m); 1721 error("%s: forwarding request failed: %s", __func__, e); 1722 return -1; 1723 default: 1724 fatal("%s: unexpected response from master 0x%08x", 1725 __func__, type); 1726 } 1727 buffer_free(&m); 1728 1729 muxclient_request_id++; 1730 return 0; 1731 } 1732 1733 static int 1734 mux_client_forwards(int fd, int cancel_flag) 1735 { 1736 int i, ret = 0; 1737 1738 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1739 cancel_flag ? "cancel" : "request", 1740 options.num_local_forwards, options.num_remote_forwards); 1741 1742 /* XXX ExitOnForwardingFailure */ 1743 for (i = 0; i < options.num_local_forwards; i++) { 1744 if (mux_client_forward(fd, cancel_flag, 1745 options.local_forwards[i].connect_port == 0 ? 1746 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1747 options.local_forwards + i) != 0) 1748 ret = -1; 1749 } 1750 for (i = 0; i < options.num_remote_forwards; i++) { 1751 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1752 options.remote_forwards + i) != 0) 1753 ret = -1; 1754 } 1755 return ret; 1756 } 1757 1758 static int 1759 mux_client_request_session(int fd) 1760 { 1761 Buffer m; 1762 char *e, *term; 1763 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1764 extern char **environ; 1765 int devnull, rawmode; 1766 1767 debug3("%s: entering", __func__); 1768 1769 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1770 error("%s: master alive request failed", __func__); 1771 return -1; 1772 } 1773 1774 signal(SIGPIPE, SIG_IGN); 1775 1776 if (stdin_null_flag) { 1777 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1778 fatal("open(/dev/null): %s", strerror(errno)); 1779 if (dup2(devnull, STDIN_FILENO) == -1) 1780 fatal("dup2: %s", strerror(errno)); 1781 if (devnull > STDERR_FILENO) 1782 close(devnull); 1783 } 1784 1785 term = getenv("TERM"); 1786 1787 buffer_init(&m); 1788 buffer_put_int(&m, MUX_C_NEW_SESSION); 1789 buffer_put_int(&m, muxclient_request_id); 1790 buffer_put_cstring(&m, ""); /* reserved */ 1791 buffer_put_int(&m, tty_flag); 1792 buffer_put_int(&m, options.forward_x11); 1793 buffer_put_int(&m, options.forward_agent); 1794 buffer_put_int(&m, subsystem_flag); 1795 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1796 0xffffffff : (u_int)options.escape_char); 1797 buffer_put_cstring(&m, term == NULL ? "" : term); 1798 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1799 1800 if (options.num_send_env > 0 && environ != NULL) { 1801 /* Pass environment */ 1802 for (i = 0; environ[i] != NULL; i++) { 1803 if (env_permitted(environ[i])) { 1804 buffer_put_cstring(&m, environ[i]); 1805 } 1806 } 1807 } 1808 1809 if (mux_client_write_packet(fd, &m) != 0) 1810 fatal("%s: write packet: %s", __func__, strerror(errno)); 1811 1812 /* Send the stdio file descriptors */ 1813 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1814 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1815 mm_send_fd(fd, STDERR_FILENO) == -1) 1816 fatal("%s: send fds failed", __func__); 1817 1818 debug3("%s: session request sent", __func__); 1819 1820 /* Read their reply */ 1821 buffer_clear(&m); 1822 if (mux_client_read_packet(fd, &m) != 0) { 1823 error("%s: read from master failed: %s", 1824 __func__, strerror(errno)); 1825 buffer_free(&m); 1826 return -1; 1827 } 1828 1829 type = buffer_get_int(&m); 1830 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1831 fatal("%s: out of sequence reply: my id %u theirs %u", 1832 __func__, muxclient_request_id, rid); 1833 switch (type) { 1834 case MUX_S_SESSION_OPENED: 1835 sid = buffer_get_int(&m); 1836 debug("%s: master session id: %u", __func__, sid); 1837 break; 1838 case MUX_S_PERMISSION_DENIED: 1839 e = buffer_get_string(&m, NULL); 1840 buffer_free(&m); 1841 error("Master refused session request: %s", e); 1842 return -1; 1843 case MUX_S_FAILURE: 1844 e = buffer_get_string(&m, NULL); 1845 buffer_free(&m); 1846 error("%s: session request failed: %s", __func__, e); 1847 return -1; 1848 default: 1849 buffer_free(&m); 1850 error("%s: unexpected response from master 0x%08x", 1851 __func__, type); 1852 return -1; 1853 } 1854 muxclient_request_id++; 1855 1856 signal(SIGHUP, control_client_sighandler); 1857 signal(SIGINT, control_client_sighandler); 1858 signal(SIGTERM, control_client_sighandler); 1859 signal(SIGWINCH, control_client_sigrelay); 1860 1861 rawmode = tty_flag; 1862 if (tty_flag) 1863 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1864 1865 /* 1866 * Stick around until the controlee closes the client_fd. 1867 * Before it does, it is expected to write an exit message. 1868 * This process must read the value and wait for the closure of 1869 * the client_fd; if this one closes early, the multiplex master will 1870 * terminate early too (possibly losing data). 1871 */ 1872 for (exitval = 255, exitval_seen = 0;;) { 1873 buffer_clear(&m); 1874 if (mux_client_read_packet(fd, &m) != 0) 1875 break; 1876 type = buffer_get_int(&m); 1877 switch (type) { 1878 case MUX_S_TTY_ALLOC_FAIL: 1879 if ((esid = buffer_get_int(&m)) != sid) 1880 fatal("%s: tty alloc fail on unknown session: " 1881 "my id %u theirs %u", 1882 __func__, sid, esid); 1883 leave_raw_mode(options.request_tty == 1884 REQUEST_TTY_FORCE); 1885 rawmode = 0; 1886 continue; 1887 case MUX_S_EXIT_MESSAGE: 1888 if ((esid = buffer_get_int(&m)) != sid) 1889 fatal("%s: exit on unknown session: " 1890 "my id %u theirs %u", 1891 __func__, sid, esid); 1892 if (exitval_seen) 1893 fatal("%s: exitval sent twice", __func__); 1894 exitval = buffer_get_int(&m); 1895 exitval_seen = 1; 1896 continue; 1897 default: 1898 e = buffer_get_string(&m, NULL); 1899 fatal("%s: master returned error: %s", __func__, e); 1900 } 1901 } 1902 1903 close(fd); 1904 if (rawmode) 1905 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1906 1907 if (muxclient_terminate) { 1908 debug2("Exiting on signal %d", muxclient_terminate); 1909 exitval = 255; 1910 } else if (!exitval_seen) { 1911 debug2("Control master terminated unexpectedly"); 1912 exitval = 255; 1913 } else 1914 debug2("Received exit status from master %d", exitval); 1915 1916 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1917 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1918 1919 exit(exitval); 1920 } 1921 1922 static int 1923 mux_client_request_stdio_fwd(int fd) 1924 { 1925 Buffer m; 1926 char *e; 1927 u_int type, rid, sid; 1928 int devnull; 1929 1930 debug3("%s: entering", __func__); 1931 1932 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1933 error("%s: master alive request failed", __func__); 1934 return -1; 1935 } 1936 1937 signal(SIGPIPE, SIG_IGN); 1938 1939 if (stdin_null_flag) { 1940 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1941 fatal("open(/dev/null): %s", strerror(errno)); 1942 if (dup2(devnull, STDIN_FILENO) == -1) 1943 fatal("dup2: %s", strerror(errno)); 1944 if (devnull > STDERR_FILENO) 1945 close(devnull); 1946 } 1947 1948 buffer_init(&m); 1949 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1950 buffer_put_int(&m, muxclient_request_id); 1951 buffer_put_cstring(&m, ""); /* reserved */ 1952 buffer_put_cstring(&m, stdio_forward_host); 1953 buffer_put_int(&m, stdio_forward_port); 1954 1955 if (mux_client_write_packet(fd, &m) != 0) 1956 fatal("%s: write packet: %s", __func__, strerror(errno)); 1957 1958 /* Send the stdio file descriptors */ 1959 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1960 mm_send_fd(fd, STDOUT_FILENO) == -1) 1961 fatal("%s: send fds failed", __func__); 1962 1963 debug3("%s: stdio forward request sent", __func__); 1964 1965 /* Read their reply */ 1966 buffer_clear(&m); 1967 1968 if (mux_client_read_packet(fd, &m) != 0) { 1969 error("%s: read from master failed: %s", 1970 __func__, strerror(errno)); 1971 buffer_free(&m); 1972 return -1; 1973 } 1974 1975 type = buffer_get_int(&m); 1976 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1977 fatal("%s: out of sequence reply: my id %u theirs %u", 1978 __func__, muxclient_request_id, rid); 1979 switch (type) { 1980 case MUX_S_SESSION_OPENED: 1981 sid = buffer_get_int(&m); 1982 debug("%s: master session id: %u", __func__, sid); 1983 break; 1984 case MUX_S_PERMISSION_DENIED: 1985 e = buffer_get_string(&m, NULL); 1986 buffer_free(&m); 1987 fatal("Master refused stdio forwarding request: %s", e); 1988 case MUX_S_FAILURE: 1989 e = buffer_get_string(&m, NULL); 1990 buffer_free(&m); 1991 fatal("Stdio forwarding request failed: %s", e); 1992 default: 1993 buffer_free(&m); 1994 error("%s: unexpected response from master 0x%08x", 1995 __func__, type); 1996 return -1; 1997 } 1998 muxclient_request_id++; 1999 2000 signal(SIGHUP, control_client_sighandler); 2001 signal(SIGINT, control_client_sighandler); 2002 signal(SIGTERM, control_client_sighandler); 2003 signal(SIGWINCH, control_client_sigrelay); 2004 2005 /* 2006 * Stick around until the controlee closes the client_fd. 2007 */ 2008 buffer_clear(&m); 2009 if (mux_client_read_packet(fd, &m) != 0) { 2010 if (errno == EPIPE || 2011 (errno == EINTR && muxclient_terminate != 0)) 2012 return 0; 2013 fatal("%s: mux_client_read_packet: %s", 2014 __func__, strerror(errno)); 2015 } 2016 fatal("%s: master returned unexpected message %u", __func__, type); 2017 } 2018 2019 static void 2020 mux_client_request_stop_listening(int fd) 2021 { 2022 Buffer m; 2023 char *e; 2024 u_int type, rid; 2025 2026 debug3("%s: entering", __func__); 2027 2028 buffer_init(&m); 2029 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2030 buffer_put_int(&m, muxclient_request_id); 2031 2032 if (mux_client_write_packet(fd, &m) != 0) 2033 fatal("%s: write packet: %s", __func__, strerror(errno)); 2034 2035 buffer_clear(&m); 2036 2037 /* Read their reply */ 2038 if (mux_client_read_packet(fd, &m) != 0) 2039 fatal("%s: read from master failed: %s", 2040 __func__, strerror(errno)); 2041 2042 type = buffer_get_int(&m); 2043 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2044 fatal("%s: out of sequence reply: my id %u theirs %u", 2045 __func__, muxclient_request_id, rid); 2046 switch (type) { 2047 case MUX_S_OK: 2048 break; 2049 case MUX_S_PERMISSION_DENIED: 2050 e = buffer_get_string(&m, NULL); 2051 fatal("Master refused stop listening request: %s", e); 2052 case MUX_S_FAILURE: 2053 e = buffer_get_string(&m, NULL); 2054 fatal("%s: stop listening request failed: %s", __func__, e); 2055 default: 2056 fatal("%s: unexpected response from master 0x%08x", 2057 __func__, type); 2058 } 2059 buffer_free(&m); 2060 muxclient_request_id++; 2061 } 2062 2063 /* Multiplex client main loop. */ 2064 void 2065 muxclient(const char *path) 2066 { 2067 struct sockaddr_un addr; 2068 int sock; 2069 u_int pid; 2070 2071 if (muxclient_command == 0) { 2072 if (stdio_forward_host != NULL) 2073 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2074 else 2075 muxclient_command = SSHMUX_COMMAND_OPEN; 2076 } 2077 2078 switch (options.control_master) { 2079 case SSHCTL_MASTER_AUTO: 2080 case SSHCTL_MASTER_AUTO_ASK: 2081 debug("auto-mux: Trying existing master"); 2082 /* FALLTHROUGH */ 2083 case SSHCTL_MASTER_NO: 2084 break; 2085 default: 2086 return; 2087 } 2088 2089 memset(&addr, '\0', sizeof(addr)); 2090 addr.sun_family = AF_UNIX; 2091 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 2092 strlen(path) + 1; 2093 2094 if (strlcpy(addr.sun_path, path, 2095 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2096 fatal("ControlPath too long"); 2097 2098 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2099 fatal("%s socket(): %s", __func__, strerror(errno)); 2100 2101 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 2102 switch (muxclient_command) { 2103 case SSHMUX_COMMAND_OPEN: 2104 case SSHMUX_COMMAND_STDIO_FWD: 2105 break; 2106 default: 2107 fatal("Control socket connect(%.100s): %s", path, 2108 strerror(errno)); 2109 } 2110 if (errno == ECONNREFUSED && 2111 options.control_master != SSHCTL_MASTER_NO) { 2112 debug("Stale control socket %.100s, unlinking", path); 2113 unlink(path); 2114 } else if (errno == ENOENT) { 2115 debug("Control socket \"%.100s\" does not exist", path); 2116 } else { 2117 error("Control socket connect(%.100s): %s", path, 2118 strerror(errno)); 2119 } 2120 close(sock); 2121 return; 2122 } 2123 set_nonblock(sock); 2124 2125 if (mux_client_hello_exchange(sock) != 0) { 2126 error("%s: master hello exchange failed", __func__); 2127 close(sock); 2128 return; 2129 } 2130 2131 switch (muxclient_command) { 2132 case SSHMUX_COMMAND_ALIVE_CHECK: 2133 if ((pid = mux_client_request_alive(sock)) == 0) 2134 fatal("%s: master alive check failed", __func__); 2135 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 2136 exit(0); 2137 case SSHMUX_COMMAND_TERMINATE: 2138 mux_client_request_terminate(sock); 2139 fprintf(stderr, "Exit request sent.\r\n"); 2140 exit(0); 2141 case SSHMUX_COMMAND_FORWARD: 2142 if (mux_client_forwards(sock, 0) != 0) 2143 fatal("%s: master forward request failed", __func__); 2144 exit(0); 2145 case SSHMUX_COMMAND_OPEN: 2146 if (mux_client_forwards(sock, 0) != 0) { 2147 error("%s: master forward request failed", __func__); 2148 return; 2149 } 2150 mux_client_request_session(sock); 2151 return; 2152 case SSHMUX_COMMAND_STDIO_FWD: 2153 mux_client_request_stdio_fwd(sock); 2154 exit(0); 2155 case SSHMUX_COMMAND_STOP: 2156 mux_client_request_stop_listening(sock); 2157 fprintf(stderr, "Stop listening request sent.\r\n"); 2158 exit(0); 2159 case SSHMUX_COMMAND_CANCEL_FWD: 2160 if (mux_client_forwards(sock, 1) != 0) 2161 error("%s: master cancel forward request failed", 2162 __func__); 2163 exit(0); 2164 default: 2165 fatal("unrecognised muxclient_command %d", muxclient_command); 2166 } 2167 } 2168