1 /* $NetBSD: mux.c,v 1.3 2010/11/21 18:29:49 adam Exp $ */ 2 /* $OpenBSD: mux.c,v 1.21 2010/06/25 23:15:36 djm Exp $ */ 3 /* 4 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 /* ssh session multiplexing support */ 20 21 /* 22 * TODO: 23 * - Better signalling from master to slave, especially passing of 24 * error messages 25 * - Better fall-back from mux slave error to new connection. 26 * - ExitOnForwardingFailure 27 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 28 * - Support ~^Z in mux slaves. 29 * - Inspect or control sessions in master. 30 * - If we ever support the "signal" channel request, send signals on 31 * sessions in master. 32 */ 33 34 #include "includes.h" 35 __RCSID("$NetBSD: mux.c,v 1.3 2010/11/21 18:29:49 adam Exp $"); 36 #include <sys/types.h> 37 #include <sys/param.h> 38 #include <sys/queue.h> 39 #include <sys/stat.h> 40 #include <sys/socket.h> 41 #include <sys/un.h> 42 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <poll.h> 46 #include <signal.h> 47 #include <stdarg.h> 48 #include <stddef.h> 49 #include <stdlib.h> 50 #include <stdio.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <util.h> 54 #include <paths.h> 55 56 #include "atomicio.h" 57 #include "xmalloc.h" 58 #include "log.h" 59 #include "ssh.h" 60 #include "ssh2.h" 61 #include "pathnames.h" 62 #include "misc.h" 63 #include "match.h" 64 #include "buffer.h" 65 #include "channels.h" 66 #include "msg.h" 67 #include "packet.h" 68 #include "monitor_fdpass.h" 69 #include "sshpty.h" 70 #include "key.h" 71 #include "readconf.h" 72 #include "clientloop.h" 73 74 /* from ssh.c */ 75 extern int tty_flag; 76 extern int force_tty_flag; 77 extern Options options; 78 extern int stdin_null_flag; 79 extern char *host; 80 extern int subsystem_flag; 81 extern Buffer command; 82 extern volatile sig_atomic_t quit_pending; 83 extern char *stdio_forward_host; 84 extern int stdio_forward_port; 85 86 /* Context for session open confirmation callback */ 87 struct mux_session_confirm_ctx { 88 u_int want_tty; 89 u_int want_subsys; 90 u_int want_x_fwd; 91 u_int want_agent_fwd; 92 Buffer cmd; 93 char *term; 94 struct termios tio; 95 char **env; 96 u_int rid; 97 }; 98 99 /* Context for global channel callback */ 100 struct mux_channel_confirm_ctx { 101 u_int cid; /* channel id */ 102 u_int rid; /* request id */ 103 int fid; /* forward id */ 104 }; 105 106 /* fd to control socket */ 107 int muxserver_sock = -1; 108 109 /* client request id */ 110 u_int muxclient_request_id = 0; 111 112 /* Multiplexing control command */ 113 u_int muxclient_command = 0; 114 115 /* Set when signalled. */ 116 static volatile sig_atomic_t muxclient_terminate = 0; 117 118 /* PID of multiplex server */ 119 static u_int muxserver_pid = 0; 120 121 static Channel *mux_listener_channel = NULL; 122 123 struct mux_master_state { 124 int hello_rcvd; 125 }; 126 127 /* mux protocol messages */ 128 #define MUX_MSG_HELLO 0x00000001 129 #define MUX_C_NEW_SESSION 0x10000002 130 #define MUX_C_ALIVE_CHECK 0x10000004 131 #define MUX_C_TERMINATE 0x10000005 132 #define MUX_C_OPEN_FWD 0x10000006 133 #define MUX_C_CLOSE_FWD 0x10000007 134 #define MUX_C_NEW_STDIO_FWD 0x10000008 135 #define MUX_S_OK 0x80000001 136 #define MUX_S_PERMISSION_DENIED 0x80000002 137 #define MUX_S_FAILURE 0x80000003 138 #define MUX_S_EXIT_MESSAGE 0x80000004 139 #define MUX_S_ALIVE 0x80000005 140 #define MUX_S_SESSION_OPENED 0x80000006 141 #define MUX_S_REMOTE_PORT 0x80000007 142 143 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 144 #define MUX_FWD_LOCAL 1 145 #define MUX_FWD_REMOTE 2 146 #define MUX_FWD_DYNAMIC 3 147 148 static void mux_session_confirm(int, int, void *); 149 150 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 151 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 152 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 153 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 154 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 155 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 156 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 157 158 static const struct { 159 u_int type; 160 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 161 } mux_master_handlers[] = { 162 { MUX_MSG_HELLO, process_mux_master_hello }, 163 { MUX_C_NEW_SESSION, process_mux_new_session }, 164 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 165 { MUX_C_TERMINATE, process_mux_terminate }, 166 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 167 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 168 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 169 { 0, NULL } 170 }; 171 172 /* Cleanup callback fired on closure of mux slave _session_ channel */ 173 /* ARGSUSED */ 174 static void 175 mux_master_session_cleanup_cb(int cid, void *unused) 176 { 177 Channel *cc, *c = channel_by_id(cid); 178 179 debug3("%s: entering for channel %d", __func__, cid); 180 if (c == NULL) 181 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 182 if (c->ctl_chan != -1) { 183 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 184 fatal("%s: channel %d missing control channel %d", 185 __func__, c->self, c->ctl_chan); 186 c->ctl_chan = -1; 187 cc->remote_id = -1; 188 chan_rcvd_oclose(cc); 189 } 190 channel_cancel_cleanup(c->self); 191 } 192 193 /* Cleanup callback fired on closure of mux slave _control_ channel */ 194 /* ARGSUSED */ 195 static void 196 mux_master_control_cleanup_cb(int cid, void *unused) 197 { 198 Channel *sc, *c = channel_by_id(cid); 199 200 debug3("%s: entering for channel %d", __func__, cid); 201 if (c == NULL) 202 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 203 if (c->remote_id != -1) { 204 if ((sc = channel_by_id(c->remote_id)) == NULL) 205 fatal("%s: channel %d missing session channel %d", 206 __func__, c->self, c->remote_id); 207 c->remote_id = -1; 208 sc->ctl_chan = -1; 209 if (sc->type != SSH_CHANNEL_OPEN) { 210 debug2("%s: channel %d: not open", __func__, sc->self); 211 chan_mark_dead(sc); 212 } else { 213 if (sc->istate == CHAN_INPUT_OPEN) 214 chan_read_failed(sc); 215 if (sc->ostate == CHAN_OUTPUT_OPEN) 216 chan_write_failed(sc); 217 } 218 } 219 channel_cancel_cleanup(c->self); 220 } 221 222 /* Check mux client environment variables before passing them to mux master. */ 223 static int 224 env_permitted(char *env) 225 { 226 int i, ret; 227 char name[1024], *cp; 228 229 if ((cp = strchr(env, '=')) == NULL || cp == env) 230 return 0; 231 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 232 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 233 error("env_permitted: name '%.100s...' too long", env); 234 return 0; 235 } 236 237 for (i = 0; i < options.num_send_env; i++) 238 if (match_pattern(name, options.send_env[i])) 239 return 1; 240 241 return 0; 242 } 243 244 /* Mux master protocol message handlers */ 245 246 static int 247 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 248 { 249 u_int ver; 250 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 251 252 if (state == NULL) 253 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 254 if (state->hello_rcvd) { 255 error("%s: HELLO received twice", __func__); 256 return -1; 257 } 258 if (buffer_get_int_ret(&ver, m) != 0) { 259 malf: 260 error("%s: malformed message", __func__); 261 return -1; 262 } 263 if (ver != SSHMUX_VER) { 264 error("Unsupported multiplexing protocol version %d " 265 "(expected %d)", ver, SSHMUX_VER); 266 return -1; 267 } 268 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 269 270 /* No extensions are presently defined */ 271 while (buffer_len(m) > 0) { 272 char *name = buffer_get_string_ret(m, NULL); 273 char *value = buffer_get_string_ret(m, NULL); 274 275 if (name == NULL || value == NULL) { 276 if (name != NULL) 277 xfree(name); 278 goto malf; 279 } 280 debug2("Unrecognised slave extension \"%s\"", name); 281 xfree(name); 282 xfree(value); 283 } 284 state->hello_rcvd = 1; 285 return 0; 286 } 287 288 static int 289 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 290 { 291 Channel *nc; 292 struct mux_session_confirm_ctx *cctx; 293 char *reserved, *cmd, *cp; 294 u_int i, j, len, env_len, escape_char, window, packetmax; 295 int new_fd[3]; 296 297 /* Reply for SSHMUX_COMMAND_OPEN */ 298 cctx = xcalloc(1, sizeof(*cctx)); 299 cctx->term = NULL; 300 cctx->rid = rid; 301 cmd = reserved = NULL; 302 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 303 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 304 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 305 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 306 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 307 buffer_get_int_ret(&escape_char, m) != 0 || 308 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 309 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 310 malf: 311 if (cmd != NULL) 312 xfree(cmd); 313 if (reserved != NULL) 314 xfree(reserved); 315 if (cctx->term != NULL) 316 xfree(cctx->term); 317 error("%s: malformed message", __func__); 318 return -1; 319 } 320 xfree(reserved); 321 reserved = NULL; 322 323 cctx->env = NULL; 324 env_len = 0; 325 while (buffer_len(m) > 0) { 326 #define MUX_MAX_ENV_VARS 4096 327 if ((cp = buffer_get_string_ret(m, &len)) == NULL) { 328 xfree(cmd); 329 goto malf; 330 } 331 if (!env_permitted(cp)) { 332 xfree(cp); 333 continue; 334 } 335 cctx->env = xrealloc(cctx->env, env_len + 2, 336 sizeof(*cctx->env)); 337 cctx->env[env_len++] = cp; 338 cctx->env[env_len] = NULL; 339 if (env_len > MUX_MAX_ENV_VARS) { 340 error(">%d environment variables received, ignoring " 341 "additional", MUX_MAX_ENV_VARS); 342 break; 343 } 344 } 345 346 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 347 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 348 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 349 cctx->want_subsys, cctx->term, cmd, env_len); 350 351 buffer_init(&cctx->cmd); 352 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 353 xfree(cmd); 354 cmd = NULL; 355 356 /* Gather fds from client */ 357 for(i = 0; i < 3; i++) { 358 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 359 error("%s: failed to receive fd %d from slave", 360 __func__, i); 361 for (j = 0; j < i; j++) 362 close(new_fd[j]); 363 for (j = 0; j < env_len; j++) 364 xfree(cctx->env[j]); 365 if (env_len > 0) 366 xfree(cctx->env); 367 xfree(cctx->term); 368 buffer_free(&cctx->cmd); 369 xfree(cctx); 370 371 /* prepare reply */ 372 buffer_put_int(r, MUX_S_FAILURE); 373 buffer_put_int(r, rid); 374 buffer_put_cstring(r, 375 "did not receive file descriptors"); 376 return -1; 377 } 378 } 379 380 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 381 new_fd[0], new_fd[1], new_fd[2]); 382 383 /* XXX support multiple child sessions in future */ 384 if (c->remote_id != -1) { 385 debug2("%s: session already open", __func__); 386 /* prepare reply */ 387 buffer_put_int(r, MUX_S_FAILURE); 388 buffer_put_int(r, rid); 389 buffer_put_cstring(r, "Multiple sessions not supported"); 390 cleanup: 391 close(new_fd[0]); 392 close(new_fd[1]); 393 close(new_fd[2]); 394 xfree(cctx->term); 395 if (env_len != 0) { 396 for (i = 0; i < env_len; i++) 397 xfree(cctx->env[i]); 398 xfree(cctx->env); 399 } 400 buffer_free(&cctx->cmd); 401 return 0; 402 } 403 404 if (options.control_master == SSHCTL_MASTER_ASK || 405 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 406 if (!ask_permission("Allow shared connection to %s? ", host)) { 407 debug2("%s: session refused by user", __func__); 408 /* prepare reply */ 409 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 410 buffer_put_int(r, rid); 411 buffer_put_cstring(r, "Permission denied"); 412 goto cleanup; 413 } 414 } 415 416 /* Try to pick up ttymodes from client before it goes raw */ 417 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 418 error("%s: tcgetattr: %s", __func__, strerror(errno)); 419 420 /* enable nonblocking unless tty */ 421 if (!isatty(new_fd[0])) 422 set_nonblock(new_fd[0]); 423 if (!isatty(new_fd[1])) 424 set_nonblock(new_fd[1]); 425 if (!isatty(new_fd[2])) 426 set_nonblock(new_fd[2]); 427 428 window = CHAN_SES_WINDOW_DEFAULT; 429 packetmax = CHAN_SES_PACKET_DEFAULT; 430 if (cctx->want_tty) { 431 window >>= 1; 432 packetmax >>= 1; 433 } 434 435 nc = channel_new("session", SSH_CHANNEL_OPENING, 436 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 437 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 438 439 nc->ctl_chan = c->self; /* link session -> control channel */ 440 c->remote_id = nc->self; /* link control -> session channel */ 441 442 if (cctx->want_tty && escape_char != 0xffffffff) { 443 channel_register_filter(nc->self, 444 client_simple_escape_filter, NULL, 445 client_filter_cleanup, 446 client_new_escape_filter_ctx((int)escape_char)); 447 } 448 449 debug2("%s: channel_new: %d linked to control channel %d", 450 __func__, nc->self, nc->ctl_chan); 451 452 channel_send_open(nc->self); 453 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 454 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 455 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 456 457 /* reply is deferred, sent by mux_session_confirm */ 458 return 0; 459 } 460 461 static int 462 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 463 { 464 debug2("%s: channel %d: alive check", __func__, c->self); 465 466 /* prepare reply */ 467 buffer_put_int(r, MUX_S_ALIVE); 468 buffer_put_int(r, rid); 469 buffer_put_int(r, (u_int)getpid()); 470 471 return 0; 472 } 473 474 static int 475 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 476 { 477 debug2("%s: channel %d: terminate request", __func__, c->self); 478 479 if (options.control_master == SSHCTL_MASTER_ASK || 480 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 481 if (!ask_permission("Terminate shared connection to %s? ", 482 host)) { 483 debug2("%s: termination refused by user", __func__); 484 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 485 buffer_put_int(r, rid); 486 buffer_put_cstring(r, "Permission denied"); 487 return 0; 488 } 489 } 490 491 quit_pending = 1; 492 buffer_put_int(r, MUX_S_OK); 493 buffer_put_int(r, rid); 494 /* XXX exit happens too soon - message never makes it to client */ 495 return 0; 496 } 497 498 static char * 499 format_forward(u_int ftype, Forward *fwd) 500 { 501 char *ret; 502 503 switch (ftype) { 504 case MUX_FWD_LOCAL: 505 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 506 (fwd->listen_host == NULL) ? 507 (options.gateway_ports ? "*" : "LOCALHOST") : 508 fwd->listen_host, fwd->listen_port, 509 fwd->connect_host, fwd->connect_port); 510 break; 511 case MUX_FWD_DYNAMIC: 512 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 513 (fwd->listen_host == NULL) ? 514 (options.gateway_ports ? "*" : "LOCALHOST") : 515 fwd->listen_host, fwd->listen_port); 516 break; 517 case MUX_FWD_REMOTE: 518 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 519 (fwd->listen_host == NULL) ? 520 "LOCALHOST" : fwd->listen_host, 521 fwd->listen_port, 522 fwd->connect_host, fwd->connect_port); 523 break; 524 default: 525 fatal("%s: unknown forward type %u", __func__, ftype); 526 } 527 return ret; 528 } 529 530 static int 531 compare_host(const char *a, const char *b) 532 { 533 if (a == NULL && b == NULL) 534 return 1; 535 if (a == NULL || b == NULL) 536 return 0; 537 return strcmp(a, b) == 0; 538 } 539 540 static int 541 compare_forward(Forward *a, Forward *b) 542 { 543 if (!compare_host(a->listen_host, b->listen_host)) 544 return 0; 545 if (a->listen_port != b->listen_port) 546 return 0; 547 if (!compare_host(a->connect_host, b->connect_host)) 548 return 0; 549 if (a->connect_port != b->connect_port) 550 return 0; 551 552 return 1; 553 } 554 555 static void 556 mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 557 { 558 struct mux_channel_confirm_ctx *fctx = ctxt; 559 char *failmsg = NULL; 560 Forward *rfwd; 561 Channel *c; 562 Buffer out; 563 564 if ((c = channel_by_id(fctx->cid)) == NULL) { 565 /* no channel for reply */ 566 error("%s: unknown channel", __func__); 567 return; 568 } 569 buffer_init(&out); 570 if (fctx->fid >= options.num_remote_forwards) { 571 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 572 goto fail; 573 } 574 rfwd = &options.remote_forwards[fctx->fid]; 575 debug("%s: %s for: listen %d, connect %s:%d", __func__, 576 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 577 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); 578 if (type == SSH2_MSG_REQUEST_SUCCESS) { 579 if (rfwd->listen_port == 0) { 580 rfwd->allocated_port = packet_get_int(); 581 logit("Allocated port %u for mux remote forward" 582 " to %s:%d", rfwd->allocated_port, 583 rfwd->connect_host, rfwd->connect_port); 584 buffer_put_int(&out, MUX_S_REMOTE_PORT); 585 buffer_put_int(&out, fctx->rid); 586 buffer_put_int(&out, rfwd->allocated_port); 587 } else { 588 buffer_put_int(&out, MUX_S_OK); 589 buffer_put_int(&out, fctx->rid); 590 } 591 goto out; 592 } else { 593 xasprintf(&failmsg, "remote port forwarding failed for " 594 "listen port %d", rfwd->listen_port); 595 } 596 fail: 597 error("%s: %s", __func__, failmsg); 598 buffer_put_int(&out, MUX_S_FAILURE); 599 buffer_put_int(&out, fctx->rid); 600 buffer_put_cstring(&out, failmsg); 601 xfree(failmsg); 602 out: 603 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 604 buffer_free(&out); 605 if (c->mux_pause <= 0) 606 fatal("%s: mux_pause %d", __func__, c->mux_pause); 607 c->mux_pause = 0; /* start processing messages again */ 608 } 609 610 static int 611 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 612 { 613 Forward fwd; 614 char *fwd_desc = NULL; 615 u_int ftype; 616 int i, ret = 0, freefwd = 1; 617 618 fwd.listen_host = fwd.connect_host = NULL; 619 if (buffer_get_int_ret(&ftype, m) != 0 || 620 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 621 buffer_get_int_ret(&fwd.listen_port, m) != 0 || 622 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 623 buffer_get_int_ret(&fwd.connect_port, m) != 0) { 624 error("%s: malformed message", __func__); 625 ret = -1; 626 goto out; 627 } 628 629 if (*fwd.listen_host == '\0') { 630 xfree(fwd.listen_host); 631 fwd.listen_host = NULL; 632 } 633 if (*fwd.connect_host == '\0') { 634 xfree(fwd.connect_host); 635 fwd.connect_host = NULL; 636 } 637 638 debug2("%s: channel %d: request %s", __func__, c->self, 639 (fwd_desc = format_forward(ftype, &fwd))); 640 641 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 642 ftype != MUX_FWD_DYNAMIC) { 643 logit("%s: invalid forwarding type %u", __func__, ftype); 644 invalid: 645 if (fwd.listen_host) 646 xfree(fwd.listen_host); 647 if (fwd.connect_host) 648 xfree(fwd.connect_host); 649 buffer_put_int(r, MUX_S_FAILURE); 650 buffer_put_int(r, rid); 651 buffer_put_cstring(r, "Invalid forwarding request"); 652 return 0; 653 } 654 if (fwd.listen_port >= 65536) { 655 logit("%s: invalid listen port %u", __func__, 656 fwd.listen_port); 657 goto invalid; 658 } 659 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC && 660 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 661 logit("%s: invalid connect port %u", __func__, 662 fwd.connect_port); 663 goto invalid; 664 } 665 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) { 666 logit("%s: missing connect host", __func__); 667 goto invalid; 668 } 669 670 /* Skip forwards that have already been requested */ 671 switch (ftype) { 672 case MUX_FWD_LOCAL: 673 case MUX_FWD_DYNAMIC: 674 for (i = 0; i < options.num_local_forwards; i++) { 675 if (compare_forward(&fwd, 676 options.local_forwards + i)) { 677 exists: 678 debug2("%s: found existing forwarding", 679 __func__); 680 buffer_put_int(r, MUX_S_OK); 681 buffer_put_int(r, rid); 682 goto out; 683 } 684 } 685 break; 686 case MUX_FWD_REMOTE: 687 for (i = 0; i < options.num_remote_forwards; i++) { 688 if (compare_forward(&fwd, 689 options.remote_forwards + i)) { 690 if (fwd.listen_port != 0) 691 goto exists; 692 debug2("%s: found allocated port", 693 __func__); 694 buffer_put_int(r, MUX_S_REMOTE_PORT); 695 buffer_put_int(r, rid); 696 buffer_put_int(r, 697 options.remote_forwards[i].allocated_port); 698 goto out; 699 } 700 } 701 break; 702 } 703 704 if (options.control_master == SSHCTL_MASTER_ASK || 705 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 706 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 707 debug2("%s: forwarding refused by user", __func__); 708 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 709 buffer_put_int(r, rid); 710 buffer_put_cstring(r, "Permission denied"); 711 goto out; 712 } 713 } 714 715 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 716 if (channel_setup_local_fwd_listener(fwd.listen_host, 717 fwd.listen_port, fwd.connect_host, fwd.connect_port, 718 options.gateway_ports) < 0) { 719 fail: 720 logit("slave-requested %s failed", fwd_desc); 721 buffer_put_int(r, MUX_S_FAILURE); 722 buffer_put_int(r, rid); 723 buffer_put_cstring(r, "Port forwarding failed"); 724 goto out; 725 } 726 add_local_forward(&options, &fwd); 727 freefwd = 0; 728 } else { 729 struct mux_channel_confirm_ctx *fctx; 730 731 if (channel_request_remote_forwarding(fwd.listen_host, 732 fwd.listen_port, fwd.connect_host, fwd.connect_port) < 0) 733 goto fail; 734 add_remote_forward(&options, &fwd); 735 fctx = xcalloc(1, sizeof(*fctx)); 736 fctx->cid = c->self; 737 fctx->rid = rid; 738 fctx->fid = options.num_remote_forwards - 1; 739 client_register_global_confirm(mux_confirm_remote_forward, 740 fctx); 741 freefwd = 0; 742 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 743 /* delayed reply in mux_confirm_remote_forward */ 744 goto out; 745 } 746 buffer_put_int(r, MUX_S_OK); 747 buffer_put_int(r, rid); 748 out: 749 if (fwd_desc != NULL) 750 xfree(fwd_desc); 751 if (freefwd) { 752 if (fwd.listen_host != NULL) 753 xfree(fwd.listen_host); 754 if (fwd.connect_host != NULL) 755 xfree(fwd.connect_host); 756 } 757 return ret; 758 } 759 760 static int 761 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 762 { 763 Forward fwd; 764 char *fwd_desc = NULL; 765 u_int ftype; 766 int ret = 0; 767 768 fwd.listen_host = fwd.connect_host = NULL; 769 if (buffer_get_int_ret(&ftype, m) != 0 || 770 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 771 buffer_get_int_ret(&fwd.listen_port, m) != 0 || 772 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 773 buffer_get_int_ret(&fwd.connect_port, m) != 0) { 774 error("%s: malformed message", __func__); 775 ret = -1; 776 goto out; 777 } 778 779 if (*fwd.listen_host == '\0') { 780 xfree(fwd.listen_host); 781 fwd.listen_host = NULL; 782 } 783 if (*fwd.connect_host == '\0') { 784 xfree(fwd.connect_host); 785 fwd.connect_host = NULL; 786 } 787 788 debug2("%s: channel %d: request %s", __func__, c->self, 789 (fwd_desc = format_forward(ftype, &fwd))); 790 791 /* XXX implement this */ 792 buffer_put_int(r, MUX_S_FAILURE); 793 buffer_put_int(r, rid); 794 buffer_put_cstring(r, "unimplemented"); 795 796 out: 797 if (fwd_desc != NULL) 798 xfree(fwd_desc); 799 if (fwd.listen_host != NULL) 800 xfree(fwd.listen_host); 801 if (fwd.connect_host != NULL) 802 xfree(fwd.connect_host); 803 804 return ret; 805 } 806 807 static int 808 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 809 { 810 Channel *nc; 811 char *reserved, *chost; 812 u_int cport, i, j; 813 int new_fd[2]; 814 815 chost = reserved = NULL; 816 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 817 (chost = buffer_get_string_ret(m, NULL)) == NULL || 818 buffer_get_int_ret(&cport, m) != 0) { 819 if (reserved != NULL) 820 xfree(reserved); 821 if (chost != NULL) 822 xfree(chost); 823 error("%s: malformed message", __func__); 824 return -1; 825 } 826 xfree(reserved); 827 828 debug2("%s: channel %d: request stdio fwd to %s:%u", 829 __func__, c->self, chost, cport); 830 831 /* Gather fds from client */ 832 for(i = 0; i < 2; i++) { 833 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 834 error("%s: failed to receive fd %d from slave", 835 __func__, i); 836 for (j = 0; j < i; j++) 837 close(new_fd[j]); 838 xfree(chost); 839 840 /* prepare reply */ 841 buffer_put_int(r, MUX_S_FAILURE); 842 buffer_put_int(r, rid); 843 buffer_put_cstring(r, 844 "did not receive file descriptors"); 845 return -1; 846 } 847 } 848 849 debug3("%s: got fds stdin %d, stdout %d", __func__, 850 new_fd[0], new_fd[1]); 851 852 /* XXX support multiple child sessions in future */ 853 if (c->remote_id != -1) { 854 debug2("%s: session already open", __func__); 855 /* prepare reply */ 856 buffer_put_int(r, MUX_S_FAILURE); 857 buffer_put_int(r, rid); 858 buffer_put_cstring(r, "Multiple sessions not supported"); 859 cleanup: 860 close(new_fd[0]); 861 close(new_fd[1]); 862 xfree(chost); 863 return 0; 864 } 865 866 if (options.control_master == SSHCTL_MASTER_ASK || 867 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 868 if (!ask_permission("Allow forward to to %s:%u? ", 869 chost, cport)) { 870 debug2("%s: stdio fwd refused by user", __func__); 871 /* prepare reply */ 872 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 873 buffer_put_int(r, rid); 874 buffer_put_cstring(r, "Permission denied"); 875 goto cleanup; 876 } 877 } 878 879 /* enable nonblocking unless tty */ 880 if (!isatty(new_fd[0])) 881 set_nonblock(new_fd[0]); 882 if (!isatty(new_fd[1])) 883 set_nonblock(new_fd[1]); 884 885 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 886 887 nc->ctl_chan = c->self; /* link session -> control channel */ 888 c->remote_id = nc->self; /* link control -> session channel */ 889 890 debug2("%s: channel_new: %d linked to control channel %d", 891 __func__, nc->self, nc->ctl_chan); 892 893 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 894 895 /* prepare reply */ 896 /* XXX defer until channel confirmed */ 897 buffer_put_int(r, MUX_S_SESSION_OPENED); 898 buffer_put_int(r, rid); 899 buffer_put_int(r, nc->self); 900 901 return 0; 902 } 903 904 /* Channel callbacks fired on read/write from mux slave fd */ 905 static int 906 mux_master_read_cb(Channel *c) 907 { 908 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 909 Buffer in, out; 910 void *ptr; 911 u_int type, rid, have, i; 912 int ret = -1; 913 914 /* Setup ctx and */ 915 if (c->mux_ctx == NULL) { 916 state = xcalloc(1, sizeof(*state)); 917 c->mux_ctx = state; 918 channel_register_cleanup(c->self, 919 mux_master_control_cleanup_cb, 0); 920 921 /* Send hello */ 922 buffer_init(&out); 923 buffer_put_int(&out, MUX_MSG_HELLO); 924 buffer_put_int(&out, SSHMUX_VER); 925 /* no extensions */ 926 buffer_put_string(&c->output, buffer_ptr(&out), 927 buffer_len(&out)); 928 buffer_free(&out); 929 debug3("%s: channel %d: hello sent", __func__, c->self); 930 return 0; 931 } 932 933 buffer_init(&in); 934 buffer_init(&out); 935 936 /* Channel code ensures that we receive whole packets */ 937 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 938 malf: 939 error("%s: malformed message", __func__); 940 goto out; 941 } 942 buffer_append(&in, ptr, have); 943 944 if (buffer_get_int_ret(&type, &in) != 0) 945 goto malf; 946 debug3("%s: channel %d packet type 0x%08x len %u", 947 __func__, c->self, type, buffer_len(&in)); 948 949 if (type == MUX_MSG_HELLO) 950 rid = 0; 951 else { 952 if (!state->hello_rcvd) { 953 error("%s: expected MUX_MSG_HELLO(0x%08x), " 954 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 955 goto out; 956 } 957 if (buffer_get_int_ret(&rid, &in) != 0) 958 goto malf; 959 } 960 961 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 962 if (type == mux_master_handlers[i].type) { 963 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 964 break; 965 } 966 } 967 if (mux_master_handlers[i].handler == NULL) { 968 error("%s: unsupported mux message 0x%08x", __func__, type); 969 buffer_put_int(&out, MUX_S_FAILURE); 970 buffer_put_int(&out, rid); 971 buffer_put_cstring(&out, "unsupported request"); 972 ret = 0; 973 } 974 /* Enqueue reply packet */ 975 if (buffer_len(&out) != 0) { 976 buffer_put_string(&c->output, buffer_ptr(&out), 977 buffer_len(&out)); 978 } 979 out: 980 buffer_free(&in); 981 buffer_free(&out); 982 return ret; 983 } 984 985 void 986 mux_exit_message(Channel *c, int exitval) 987 { 988 Buffer m; 989 Channel *mux_chan; 990 991 debug3("%s: channel %d: exit message, evitval %d", __func__, c->self, 992 exitval); 993 994 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 995 fatal("%s: channel %d missing mux channel %d", 996 __func__, c->self, c->ctl_chan); 997 998 /* Append exit message packet to control socket output queue */ 999 buffer_init(&m); 1000 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1001 buffer_put_int(&m, c->self); 1002 buffer_put_int(&m, exitval); 1003 1004 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1005 buffer_free(&m); 1006 } 1007 1008 /* Prepare a mux master to listen on a Unix domain socket. */ 1009 void 1010 muxserver_listen(void) 1011 { 1012 struct sockaddr_un addr; 1013 mode_t old_umask; 1014 1015 if (options.control_path == NULL || 1016 options.control_master == SSHCTL_MASTER_NO) 1017 return; 1018 1019 debug("setting up multiplex master socket"); 1020 1021 memset(&addr, '\0', sizeof(addr)); 1022 addr.sun_family = AF_UNIX; 1023 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 1024 strlen(options.control_path) + 1; 1025 1026 if (strlcpy(addr.sun_path, options.control_path, 1027 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 1028 fatal("ControlPath too long"); 1029 1030 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1031 fatal("%s socket(): %s", __func__, strerror(errno)); 1032 1033 old_umask = umask(0177); 1034 if (bind(muxserver_sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 1035 muxserver_sock = -1; 1036 if (errno == EINVAL || errno == EADDRINUSE) { 1037 error("ControlSocket %s already exists, " 1038 "disabling multiplexing", options.control_path); 1039 close(muxserver_sock); 1040 muxserver_sock = -1; 1041 xfree(options.control_path); 1042 options.control_path = NULL; 1043 options.control_master = SSHCTL_MASTER_NO; 1044 return; 1045 } else 1046 fatal("%s bind(): %s", __func__, strerror(errno)); 1047 } 1048 umask(old_umask); 1049 1050 if (listen(muxserver_sock, 64) == -1) 1051 fatal("%s listen(): %s", __func__, strerror(errno)); 1052 1053 set_nonblock(muxserver_sock); 1054 1055 mux_listener_channel = channel_new("mux listener", 1056 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1057 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1058 0, addr.sun_path, 1); 1059 mux_listener_channel->mux_rcb = mux_master_read_cb; 1060 debug3("%s: mux listener channel %d fd %d", __func__, 1061 mux_listener_channel->self, mux_listener_channel->sock); 1062 } 1063 1064 /* Callback on open confirmation in mux master for a mux client session. */ 1065 static void 1066 mux_session_confirm(int id, int success, void *arg) 1067 { 1068 struct mux_session_confirm_ctx *cctx = arg; 1069 const char *display; 1070 Channel *c, *cc; 1071 int i; 1072 Buffer reply; 1073 1074 if (cctx == NULL) 1075 fatal("%s: cctx == NULL", __func__); 1076 if ((c = channel_by_id(id)) == NULL) 1077 fatal("%s: no channel for id %d", __func__, id); 1078 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1079 fatal("%s: channel %d lacks control channel %d", __func__, 1080 id, c->ctl_chan); 1081 1082 if (!success) { 1083 debug3("%s: sending failure reply", __func__); 1084 /* prepare reply */ 1085 buffer_init(&reply); 1086 buffer_put_int(&reply, MUX_S_FAILURE); 1087 buffer_put_int(&reply, cctx->rid); 1088 buffer_put_cstring(&reply, "Session open refused by peer"); 1089 goto done; 1090 } 1091 1092 display = getenv("DISPLAY"); 1093 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1094 char *proto, *data; 1095 1096 /* Get reasonable local authentication information. */ 1097 client_x11_get_proto(display, options.xauth_location, 1098 options.forward_x11_trusted, options.forward_x11_timeout, 1099 &proto, &data); 1100 /* Request forwarding with authentication spoofing. */ 1101 debug("Requesting X11 forwarding with authentication " 1102 "spoofing."); 1103 x11_request_forwarding_with_spoofing(id, display, proto, data); 1104 /* XXX wait for reply */ 1105 } 1106 1107 if (cctx->want_agent_fwd && options.forward_agent) { 1108 debug("Requesting authentication agent forwarding."); 1109 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1110 packet_send(); 1111 } 1112 1113 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1114 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1115 1116 debug3("%s: sending success reply", __func__); 1117 /* prepare reply */ 1118 buffer_init(&reply); 1119 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1120 buffer_put_int(&reply, cctx->rid); 1121 buffer_put_int(&reply, c->self); 1122 1123 done: 1124 /* Send reply */ 1125 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1126 buffer_free(&reply); 1127 1128 if (cc->mux_pause <= 0) 1129 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1130 cc->mux_pause = 0; /* start processing messages again */ 1131 c->open_confirm_ctx = NULL; 1132 buffer_free(&cctx->cmd); 1133 xfree(cctx->term); 1134 if (cctx->env != NULL) { 1135 for (i = 0; cctx->env[i] != NULL; i++) 1136 xfree(cctx->env[i]); 1137 xfree(cctx->env); 1138 } 1139 xfree(cctx); 1140 } 1141 1142 /* ** Multiplexing client support */ 1143 1144 /* Exit signal handler */ 1145 static void 1146 control_client_sighandler(int signo) 1147 { 1148 muxclient_terminate = signo; 1149 } 1150 1151 /* 1152 * Relay signal handler - used to pass some signals from mux client to 1153 * mux master. 1154 */ 1155 static void 1156 control_client_sigrelay(int signo) 1157 { 1158 int save_errno = errno; 1159 1160 if (muxserver_pid > 1) 1161 kill(muxserver_pid, signo); 1162 1163 errno = save_errno; 1164 } 1165 1166 static int 1167 mux_client_read(int fd, Buffer *b, u_int need) 1168 { 1169 u_int have; 1170 ssize_t len; 1171 u_char *p; 1172 struct pollfd pfd; 1173 1174 pfd.fd = fd; 1175 pfd.events = POLLIN; 1176 p = buffer_append_space(b, need); 1177 for (have = 0; have < need; ) { 1178 if (muxclient_terminate) { 1179 errno = EINTR; 1180 return -1; 1181 } 1182 len = read(fd, p + have, need - have); 1183 if (len < 0) { 1184 switch (errno) { 1185 case EAGAIN: 1186 (void)poll(&pfd, 1, -1); 1187 /* FALLTHROUGH */ 1188 case EINTR: 1189 continue; 1190 default: 1191 return -1; 1192 } 1193 } 1194 if (len == 0) { 1195 errno = EPIPE; 1196 return -1; 1197 } 1198 have += (u_int)len; 1199 } 1200 return 0; 1201 } 1202 1203 static int 1204 mux_client_write_packet(int fd, Buffer *m) 1205 { 1206 Buffer queue; 1207 u_int have, need; 1208 int oerrno, len; 1209 u_char *ptr; 1210 struct pollfd pfd; 1211 1212 pfd.fd = fd; 1213 pfd.events = POLLOUT; 1214 buffer_init(&queue); 1215 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1216 1217 need = buffer_len(&queue); 1218 ptr = buffer_ptr(&queue); 1219 1220 for (have = 0; have < need; ) { 1221 if (muxclient_terminate) { 1222 buffer_free(&queue); 1223 errno = EINTR; 1224 return -1; 1225 } 1226 len = write(fd, ptr + have, need - have); 1227 if (len < 0) { 1228 switch (errno) { 1229 case EAGAIN: 1230 (void)poll(&pfd, 1, -1); 1231 /* FALLTHROUGH */ 1232 case EINTR: 1233 continue; 1234 default: 1235 oerrno = errno; 1236 buffer_free(&queue); 1237 errno = oerrno; 1238 return -1; 1239 } 1240 } 1241 if (len == 0) { 1242 buffer_free(&queue); 1243 errno = EPIPE; 1244 return -1; 1245 } 1246 have += (u_int)len; 1247 } 1248 buffer_free(&queue); 1249 return 0; 1250 } 1251 1252 static int 1253 mux_client_read_packet(int fd, Buffer *m) 1254 { 1255 Buffer queue; 1256 u_int need, have; 1257 void *ptr; 1258 int oerrno; 1259 1260 buffer_init(&queue); 1261 if (mux_client_read(fd, &queue, 4) != 0) { 1262 if ((oerrno = errno) == EPIPE) 1263 debug3("%s: read header failed: %s", __func__, strerror(errno)); 1264 errno = oerrno; 1265 return -1; 1266 } 1267 need = get_u32(buffer_ptr(&queue)); 1268 if (mux_client_read(fd, &queue, need) != 0) { 1269 oerrno = errno; 1270 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1271 errno = oerrno; 1272 return -1; 1273 } 1274 ptr = buffer_get_string_ptr(&queue, &have); 1275 buffer_append(m, ptr, have); 1276 buffer_free(&queue); 1277 return 0; 1278 } 1279 1280 static int 1281 mux_client_hello_exchange(int fd) 1282 { 1283 Buffer m; 1284 u_int type, ver; 1285 1286 buffer_init(&m); 1287 buffer_put_int(&m, MUX_MSG_HELLO); 1288 buffer_put_int(&m, SSHMUX_VER); 1289 /* no extensions */ 1290 1291 if (mux_client_write_packet(fd, &m) != 0) 1292 fatal("%s: write packet: %s", __func__, strerror(errno)); 1293 1294 buffer_clear(&m); 1295 1296 /* Read their HELLO */ 1297 if (mux_client_read_packet(fd, &m) != 0) { 1298 buffer_free(&m); 1299 return -1; 1300 } 1301 1302 type = buffer_get_int(&m); 1303 if (type != MUX_MSG_HELLO) 1304 fatal("%s: expected HELLO (%u) received %u", 1305 __func__, MUX_MSG_HELLO, type); 1306 ver = buffer_get_int(&m); 1307 if (ver != SSHMUX_VER) 1308 fatal("Unsupported multiplexing protocol version %d " 1309 "(expected %d)", ver, SSHMUX_VER); 1310 debug2("%s: master version %u", __func__, ver); 1311 /* No extensions are presently defined */ 1312 while (buffer_len(&m) > 0) { 1313 char *name = buffer_get_string(&m, NULL); 1314 char *value = buffer_get_string(&m, NULL); 1315 1316 debug2("Unrecognised master extension \"%s\"", name); 1317 xfree(name); 1318 xfree(value); 1319 } 1320 buffer_free(&m); 1321 return 0; 1322 } 1323 1324 static u_int 1325 mux_client_request_alive(int fd) 1326 { 1327 Buffer m; 1328 char *e; 1329 u_int pid, type, rid; 1330 1331 debug3("%s: entering", __func__); 1332 1333 buffer_init(&m); 1334 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1335 buffer_put_int(&m, muxclient_request_id); 1336 1337 if (mux_client_write_packet(fd, &m) != 0) 1338 fatal("%s: write packet: %s", __func__, strerror(errno)); 1339 1340 buffer_clear(&m); 1341 1342 /* Read their reply */ 1343 if (mux_client_read_packet(fd, &m) != 0) { 1344 buffer_free(&m); 1345 return 0; 1346 } 1347 1348 type = buffer_get_int(&m); 1349 if (type != MUX_S_ALIVE) { 1350 e = buffer_get_string(&m, NULL); 1351 fatal("%s: master returned error: %s", __func__, e); 1352 } 1353 1354 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1355 fatal("%s: out of sequence reply: my id %u theirs %u", 1356 __func__, muxclient_request_id, rid); 1357 pid = buffer_get_int(&m); 1358 buffer_free(&m); 1359 1360 debug3("%s: done pid = %u", __func__, pid); 1361 1362 muxclient_request_id++; 1363 1364 return pid; 1365 } 1366 1367 static void 1368 mux_client_request_terminate(int fd) 1369 { 1370 Buffer m; 1371 char *e; 1372 u_int type, rid; 1373 1374 debug3("%s: entering", __func__); 1375 1376 buffer_init(&m); 1377 buffer_put_int(&m, MUX_C_TERMINATE); 1378 buffer_put_int(&m, muxclient_request_id); 1379 1380 if (mux_client_write_packet(fd, &m) != 0) 1381 fatal("%s: write packet: %s", __func__, strerror(errno)); 1382 1383 buffer_clear(&m); 1384 1385 /* Read their reply */ 1386 if (mux_client_read_packet(fd, &m) != 0) { 1387 /* Remote end exited already */ 1388 if (errno == EPIPE) { 1389 buffer_free(&m); 1390 return; 1391 } 1392 fatal("%s: read from master failed: %s", 1393 __func__, strerror(errno)); 1394 } 1395 1396 type = buffer_get_int(&m); 1397 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1398 fatal("%s: out of sequence reply: my id %u theirs %u", 1399 __func__, muxclient_request_id, rid); 1400 switch (type) { 1401 case MUX_S_OK: 1402 break; 1403 case MUX_S_PERMISSION_DENIED: 1404 e = buffer_get_string(&m, NULL); 1405 fatal("Master refused termination request: %s", e); 1406 case MUX_S_FAILURE: 1407 e = buffer_get_string(&m, NULL); 1408 fatal("%s: termination request failed: %s", __func__, e); 1409 default: 1410 fatal("%s: unexpected response from master 0x%08x", 1411 __func__, type); 1412 } 1413 buffer_free(&m); 1414 muxclient_request_id++; 1415 } 1416 1417 static int 1418 mux_client_request_forward(int fd, u_int ftype, Forward *fwd) 1419 { 1420 Buffer m; 1421 char *e, *fwd_desc; 1422 u_int type, rid; 1423 1424 fwd_desc = format_forward(ftype, fwd); 1425 debug("Requesting %s", fwd_desc); 1426 xfree(fwd_desc); 1427 1428 buffer_init(&m); 1429 buffer_put_int(&m, MUX_C_OPEN_FWD); 1430 buffer_put_int(&m, muxclient_request_id); 1431 buffer_put_int(&m, ftype); 1432 buffer_put_cstring(&m, 1433 fwd->listen_host == NULL ? "" : fwd->listen_host); 1434 buffer_put_int(&m, fwd->listen_port); 1435 buffer_put_cstring(&m, 1436 fwd->connect_host == NULL ? "" : fwd->connect_host); 1437 buffer_put_int(&m, fwd->connect_port); 1438 1439 if (mux_client_write_packet(fd, &m) != 0) 1440 fatal("%s: write packet: %s", __func__, strerror(errno)); 1441 1442 buffer_clear(&m); 1443 1444 /* Read their reply */ 1445 if (mux_client_read_packet(fd, &m) != 0) { 1446 buffer_free(&m); 1447 return -1; 1448 } 1449 1450 type = buffer_get_int(&m); 1451 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1452 fatal("%s: out of sequence reply: my id %u theirs %u", 1453 __func__, muxclient_request_id, rid); 1454 switch (type) { 1455 case MUX_S_OK: 1456 break; 1457 case MUX_S_REMOTE_PORT: 1458 fwd->allocated_port = buffer_get_int(&m); 1459 logit("Allocated port %u for remote forward to %s:%d", 1460 fwd->allocated_port, 1461 fwd->connect_host ? fwd->connect_host : "", 1462 fwd->connect_port); 1463 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1464 fprintf(stdout, "%u\n", fwd->allocated_port); 1465 break; 1466 case MUX_S_PERMISSION_DENIED: 1467 e = buffer_get_string(&m, NULL); 1468 buffer_free(&m); 1469 error("Master refused forwarding request: %s", e); 1470 return -1; 1471 case MUX_S_FAILURE: 1472 e = buffer_get_string(&m, NULL); 1473 buffer_free(&m); 1474 error("%s: session request failed: %s", __func__, e); 1475 return -1; 1476 default: 1477 fatal("%s: unexpected response from master 0x%08x", 1478 __func__, type); 1479 } 1480 buffer_free(&m); 1481 1482 muxclient_request_id++; 1483 return 0; 1484 } 1485 1486 static int 1487 mux_client_request_forwards(int fd) 1488 { 1489 int i; 1490 1491 debug3("%s: requesting forwardings: %d local, %d remote", __func__, 1492 options.num_local_forwards, options.num_remote_forwards); 1493 1494 /* XXX ExitOnForwardingFailure */ 1495 for (i = 0; i < options.num_local_forwards; i++) { 1496 if (mux_client_request_forward(fd, 1497 options.local_forwards[i].connect_port == 0 ? 1498 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1499 options.local_forwards + i) != 0) 1500 return -1; 1501 } 1502 for (i = 0; i < options.num_remote_forwards; i++) { 1503 if (mux_client_request_forward(fd, MUX_FWD_REMOTE, 1504 options.remote_forwards + i) != 0) 1505 return -1; 1506 } 1507 return 0; 1508 } 1509 1510 static int 1511 mux_client_request_session(int fd) 1512 { 1513 Buffer m; 1514 char *e, *term; 1515 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1516 extern char **environ; 1517 int devnull; 1518 1519 debug3("%s: entering", __func__); 1520 1521 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1522 error("%s: master alive request failed", __func__); 1523 return -1; 1524 } 1525 1526 signal(SIGPIPE, SIG_IGN); 1527 1528 if (stdin_null_flag) { 1529 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1530 fatal("open(/dev/null): %s", strerror(errno)); 1531 if (dup2(devnull, STDIN_FILENO) == -1) 1532 fatal("dup2: %s", strerror(errno)); 1533 if (devnull > STDERR_FILENO) 1534 close(devnull); 1535 } 1536 1537 term = getenv("TERM"); 1538 1539 buffer_init(&m); 1540 buffer_put_int(&m, MUX_C_NEW_SESSION); 1541 buffer_put_int(&m, muxclient_request_id); 1542 buffer_put_cstring(&m, ""); /* reserved */ 1543 buffer_put_int(&m, tty_flag); 1544 buffer_put_int(&m, options.forward_x11); 1545 buffer_put_int(&m, options.forward_agent); 1546 buffer_put_int(&m, subsystem_flag); 1547 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1548 0xffffffff : (u_int)options.escape_char); 1549 buffer_put_cstring(&m, term == NULL ? "" : term); 1550 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1551 1552 if (options.num_send_env > 0 && environ != NULL) { 1553 /* Pass environment */ 1554 for (i = 0; environ[i] != NULL; i++) { 1555 if (env_permitted(environ[i])) { 1556 buffer_put_cstring(&m, environ[i]); 1557 } 1558 } 1559 } 1560 1561 if (mux_client_write_packet(fd, &m) != 0) 1562 fatal("%s: write packet: %s", __func__, strerror(errno)); 1563 1564 /* Send the stdio file descriptors */ 1565 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1566 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1567 mm_send_fd(fd, STDERR_FILENO) == -1) 1568 fatal("%s: send fds failed", __func__); 1569 1570 debug3("%s: session request sent", __func__); 1571 1572 /* Read their reply */ 1573 buffer_clear(&m); 1574 if (mux_client_read_packet(fd, &m) != 0) { 1575 error("%s: read from master failed: %s", 1576 __func__, strerror(errno)); 1577 buffer_free(&m); 1578 return -1; 1579 } 1580 1581 type = buffer_get_int(&m); 1582 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1583 fatal("%s: out of sequence reply: my id %u theirs %u", 1584 __func__, muxclient_request_id, rid); 1585 switch (type) { 1586 case MUX_S_SESSION_OPENED: 1587 sid = buffer_get_int(&m); 1588 debug("%s: master session id: %u", __func__, sid); 1589 break; 1590 case MUX_S_PERMISSION_DENIED: 1591 e = buffer_get_string(&m, NULL); 1592 buffer_free(&m); 1593 error("Master refused forwarding request: %s", e); 1594 return -1; 1595 case MUX_S_FAILURE: 1596 e = buffer_get_string(&m, NULL); 1597 buffer_free(&m); 1598 error("%s: forwarding request failed: %s", __func__, e); 1599 return -1; 1600 default: 1601 buffer_free(&m); 1602 error("%s: unexpected response from master 0x%08x", 1603 __func__, type); 1604 return -1; 1605 } 1606 muxclient_request_id++; 1607 1608 signal(SIGHUP, control_client_sighandler); 1609 signal(SIGINT, control_client_sighandler); 1610 signal(SIGTERM, control_client_sighandler); 1611 signal(SIGWINCH, control_client_sigrelay); 1612 1613 if (tty_flag) 1614 enter_raw_mode(force_tty_flag); 1615 1616 /* 1617 * Stick around until the controlee closes the client_fd. 1618 * Before it does, it is expected to write an exit message. 1619 * This process must read the value and wait for the closure of 1620 * the client_fd; if this one closes early, the multiplex master will 1621 * terminate early too (possibly losing data). 1622 */ 1623 for (exitval = 255, exitval_seen = 0;;) { 1624 buffer_clear(&m); 1625 if (mux_client_read_packet(fd, &m) != 0) 1626 break; 1627 type = buffer_get_int(&m); 1628 if (type != MUX_S_EXIT_MESSAGE) { 1629 e = buffer_get_string(&m, NULL); 1630 fatal("%s: master returned error: %s", __func__, e); 1631 } 1632 if ((esid = buffer_get_int(&m)) != sid) 1633 fatal("%s: exit on unknown session: my id %u theirs %u", 1634 __func__, sid, esid); 1635 debug("%s: master session id: %u", __func__, sid); 1636 if (exitval_seen) 1637 fatal("%s: exitval sent twice", __func__); 1638 exitval = buffer_get_int(&m); 1639 exitval_seen = 1; 1640 } 1641 1642 close(fd); 1643 leave_raw_mode(force_tty_flag); 1644 1645 if (muxclient_terminate) { 1646 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1647 exitval = 255; 1648 } else if (!exitval_seen) { 1649 debug2("Control master terminated unexpectedly"); 1650 exitval = 255; 1651 } else 1652 debug2("Received exit status from master %d", exitval); 1653 1654 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1655 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1656 1657 exit(exitval); 1658 } 1659 1660 static int 1661 mux_client_request_stdio_fwd(int fd) 1662 { 1663 Buffer m; 1664 char *e; 1665 u_int type, rid, sid; 1666 int devnull; 1667 1668 debug3("%s: entering", __func__); 1669 1670 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1671 error("%s: master alive request failed", __func__); 1672 return -1; 1673 } 1674 1675 signal(SIGPIPE, SIG_IGN); 1676 1677 if (stdin_null_flag) { 1678 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1679 fatal("open(/dev/null): %s", strerror(errno)); 1680 if (dup2(devnull, STDIN_FILENO) == -1) 1681 fatal("dup2: %s", strerror(errno)); 1682 if (devnull > STDERR_FILENO) 1683 close(devnull); 1684 } 1685 1686 buffer_init(&m); 1687 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1688 buffer_put_int(&m, muxclient_request_id); 1689 buffer_put_cstring(&m, ""); /* reserved */ 1690 buffer_put_cstring(&m, stdio_forward_host); 1691 buffer_put_int(&m, stdio_forward_port); 1692 1693 if (mux_client_write_packet(fd, &m) != 0) 1694 fatal("%s: write packet: %s", __func__, strerror(errno)); 1695 1696 /* Send the stdio file descriptors */ 1697 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1698 mm_send_fd(fd, STDOUT_FILENO) == -1) 1699 fatal("%s: send fds failed", __func__); 1700 1701 debug3("%s: stdio forward request sent", __func__); 1702 1703 /* Read their reply */ 1704 buffer_clear(&m); 1705 1706 if (mux_client_read_packet(fd, &m) != 0) { 1707 error("%s: read from master failed: %s", 1708 __func__, strerror(errno)); 1709 buffer_free(&m); 1710 return -1; 1711 } 1712 1713 type = buffer_get_int(&m); 1714 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1715 fatal("%s: out of sequence reply: my id %u theirs %u", 1716 __func__, muxclient_request_id, rid); 1717 switch (type) { 1718 case MUX_S_SESSION_OPENED: 1719 sid = buffer_get_int(&m); 1720 debug("%s: master session id: %u", __func__, sid); 1721 break; 1722 case MUX_S_PERMISSION_DENIED: 1723 e = buffer_get_string(&m, NULL); 1724 buffer_free(&m); 1725 fatal("Master refused forwarding request: %s", e); 1726 case MUX_S_FAILURE: 1727 e = buffer_get_string(&m, NULL); 1728 buffer_free(&m); 1729 fatal("%s: stdio forwarding request failed: %s", __func__, e); 1730 default: 1731 buffer_free(&m); 1732 error("%s: unexpected response from master 0x%08x", 1733 __func__, type); 1734 return -1; 1735 } 1736 muxclient_request_id++; 1737 1738 signal(SIGHUP, control_client_sighandler); 1739 signal(SIGINT, control_client_sighandler); 1740 signal(SIGTERM, control_client_sighandler); 1741 signal(SIGWINCH, control_client_sigrelay); 1742 1743 /* 1744 * Stick around until the controlee closes the client_fd. 1745 */ 1746 buffer_clear(&m); 1747 if (mux_client_read_packet(fd, &m) != 0) { 1748 if (errno == EPIPE || 1749 (errno == EINTR && muxclient_terminate != 0)) 1750 return 0; 1751 fatal("%s: mux_client_read_packet: %s", 1752 __func__, strerror(errno)); 1753 } 1754 fatal("%s: master returned unexpected message %u", __func__, type); 1755 } 1756 1757 /* Multiplex client main loop. */ 1758 void 1759 muxclient(const char *path) 1760 { 1761 struct sockaddr_un addr; 1762 int sock; 1763 u_int pid; 1764 1765 if (muxclient_command == 0) { 1766 if (stdio_forward_host != NULL) 1767 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 1768 else 1769 muxclient_command = SSHMUX_COMMAND_OPEN; 1770 } 1771 1772 switch (options.control_master) { 1773 case SSHCTL_MASTER_AUTO: 1774 case SSHCTL_MASTER_AUTO_ASK: 1775 debug("auto-mux: Trying existing master"); 1776 /* FALLTHROUGH */ 1777 case SSHCTL_MASTER_NO: 1778 break; 1779 default: 1780 return; 1781 } 1782 1783 memset(&addr, '\0', sizeof(addr)); 1784 addr.sun_family = AF_UNIX; 1785 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 1786 strlen(path) + 1; 1787 1788 if (strlcpy(addr.sun_path, path, 1789 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 1790 fatal("ControlPath too long"); 1791 1792 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1793 fatal("%s socket(): %s", __func__, strerror(errno)); 1794 1795 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 1796 switch (muxclient_command) { 1797 case SSHMUX_COMMAND_OPEN: 1798 case SSHMUX_COMMAND_STDIO_FWD: 1799 break; 1800 default: 1801 fatal("Control socket connect(%.100s): %s", path, 1802 strerror(errno)); 1803 } 1804 if (errno == ENOENT) 1805 debug("Control socket \"%.100s\" does not exist", path); 1806 else { 1807 error("Control socket connect(%.100s): %s", path, 1808 strerror(errno)); 1809 } 1810 close(sock); 1811 return; 1812 } 1813 set_nonblock(sock); 1814 1815 if (mux_client_hello_exchange(sock) != 0) { 1816 error("%s: master hello exchange failed", __func__); 1817 close(sock); 1818 return; 1819 } 1820 1821 switch (muxclient_command) { 1822 case SSHMUX_COMMAND_ALIVE_CHECK: 1823 if ((pid = mux_client_request_alive(sock)) == 0) 1824 fatal("%s: master alive check failed", __func__); 1825 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 1826 exit(0); 1827 case SSHMUX_COMMAND_TERMINATE: 1828 mux_client_request_terminate(sock); 1829 fprintf(stderr, "Exit request sent.\r\n"); 1830 exit(0); 1831 case SSHMUX_COMMAND_FORWARD: 1832 if (mux_client_request_forwards(sock) != 0) 1833 fatal("%s: master forward request failed", __func__); 1834 exit(0); 1835 case SSHMUX_COMMAND_OPEN: 1836 if (mux_client_request_forwards(sock) != 0) { 1837 error("%s: master forward request failed", __func__); 1838 return; 1839 } 1840 mux_client_request_session(sock); 1841 return; 1842 case SSHMUX_COMMAND_STDIO_FWD: 1843 mux_client_request_stdio_fwd(sock); 1844 exit(0); 1845 default: 1846 fatal("unrecognised muxclient_command %d", muxclient_command); 1847 } 1848 } 1849