1 /* $OpenBSD: mux.c,v 1.24 2011/01/13 21:54:53 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 "includes.h" 34 35 #include <sys/types.h> 36 #include <sys/param.h> 37 #include <sys/stat.h> 38 #include <sys/socket.h> 39 #include <sys/un.h> 40 41 #include <errno.h> 42 #include <fcntl.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 #ifdef HAVE_PATHS_H 51 #include <paths.h> 52 #endif 53 54 #ifdef HAVE_POLL_H 55 #include <poll.h> 56 #else 57 # ifdef HAVE_SYS_POLL_H 58 # include <sys/poll.h> 59 # endif 60 #endif 61 62 #ifdef HAVE_UTIL_H 63 # include <util.h> 64 #endif 65 66 #ifdef HAVE_LIBUTIL_H 67 # include <libutil.h> 68 #endif 69 70 #include "openbsd-compat/sys-queue.h" 71 #include "xmalloc.h" 72 #include "log.h" 73 #include "ssh.h" 74 #include "ssh2.h" 75 #include "pathnames.h" 76 #include "misc.h" 77 #include "match.h" 78 #include "buffer.h" 79 #include "channels.h" 80 #include "msg.h" 81 #include "packet.h" 82 #include "monitor_fdpass.h" 83 #include "sshpty.h" 84 #include "key.h" 85 #include "readconf.h" 86 #include "clientloop.h" 87 88 /* from ssh.c */ 89 extern int tty_flag; 90 extern int force_tty_flag; 91 extern Options options; 92 extern int stdin_null_flag; 93 extern char *host; 94 extern int subsystem_flag; 95 extern Buffer command; 96 extern volatile sig_atomic_t quit_pending; 97 extern char *stdio_forward_host; 98 extern int stdio_forward_port; 99 100 /* Context for session open confirmation callback */ 101 struct mux_session_confirm_ctx { 102 u_int want_tty; 103 u_int want_subsys; 104 u_int want_x_fwd; 105 u_int want_agent_fwd; 106 Buffer cmd; 107 char *term; 108 struct termios tio; 109 char **env; 110 u_int rid; 111 }; 112 113 /* Context for global channel callback */ 114 struct mux_channel_confirm_ctx { 115 u_int cid; /* channel id */ 116 u_int rid; /* request id */ 117 int fid; /* forward id */ 118 }; 119 120 /* fd to control socket */ 121 int muxserver_sock = -1; 122 123 /* client request id */ 124 u_int muxclient_request_id = 0; 125 126 /* Multiplexing control command */ 127 u_int muxclient_command = 0; 128 129 /* Set when signalled. */ 130 static volatile sig_atomic_t muxclient_terminate = 0; 131 132 /* PID of multiplex server */ 133 static u_int muxserver_pid = 0; 134 135 static Channel *mux_listener_channel = NULL; 136 137 struct mux_master_state { 138 int hello_rcvd; 139 }; 140 141 /* mux protocol messages */ 142 #define MUX_MSG_HELLO 0x00000001 143 #define MUX_C_NEW_SESSION 0x10000002 144 #define MUX_C_ALIVE_CHECK 0x10000004 145 #define MUX_C_TERMINATE 0x10000005 146 #define MUX_C_OPEN_FWD 0x10000006 147 #define MUX_C_CLOSE_FWD 0x10000007 148 #define MUX_C_NEW_STDIO_FWD 0x10000008 149 #define MUX_S_OK 0x80000001 150 #define MUX_S_PERMISSION_DENIED 0x80000002 151 #define MUX_S_FAILURE 0x80000003 152 #define MUX_S_EXIT_MESSAGE 0x80000004 153 #define MUX_S_ALIVE 0x80000005 154 #define MUX_S_SESSION_OPENED 0x80000006 155 #define MUX_S_REMOTE_PORT 0x80000007 156 157 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 158 #define MUX_FWD_LOCAL 1 159 #define MUX_FWD_REMOTE 2 160 #define MUX_FWD_DYNAMIC 3 161 162 static void mux_session_confirm(int, int, void *); 163 164 static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); 165 static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); 166 static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); 167 static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); 168 static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); 169 static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); 170 static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); 171 172 static const struct { 173 u_int type; 174 int (*handler)(u_int, Channel *, Buffer *, Buffer *); 175 } mux_master_handlers[] = { 176 { MUX_MSG_HELLO, process_mux_master_hello }, 177 { MUX_C_NEW_SESSION, process_mux_new_session }, 178 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 179 { MUX_C_TERMINATE, process_mux_terminate }, 180 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 181 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 182 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 183 { 0, NULL } 184 }; 185 186 /* Cleanup callback fired on closure of mux slave _session_ channel */ 187 /* ARGSUSED */ 188 static void 189 mux_master_session_cleanup_cb(int cid, void *unused) 190 { 191 Channel *cc, *c = channel_by_id(cid); 192 193 debug3("%s: entering for channel %d", __func__, cid); 194 if (c == NULL) 195 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 196 if (c->ctl_chan != -1) { 197 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 198 fatal("%s: channel %d missing control channel %d", 199 __func__, c->self, c->ctl_chan); 200 c->ctl_chan = -1; 201 cc->remote_id = -1; 202 chan_rcvd_oclose(cc); 203 } 204 channel_cancel_cleanup(c->self); 205 } 206 207 /* Cleanup callback fired on closure of mux slave _control_ channel */ 208 /* ARGSUSED */ 209 static void 210 mux_master_control_cleanup_cb(int cid, void *unused) 211 { 212 Channel *sc, *c = channel_by_id(cid); 213 214 debug3("%s: entering for channel %d", __func__, cid); 215 if (c == NULL) 216 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 217 if (c->remote_id != -1) { 218 if ((sc = channel_by_id(c->remote_id)) == NULL) 219 fatal("%s: channel %d missing session channel %d", 220 __func__, c->self, c->remote_id); 221 c->remote_id = -1; 222 sc->ctl_chan = -1; 223 if (sc->type != SSH_CHANNEL_OPEN) { 224 debug2("%s: channel %d: not open", __func__, sc->self); 225 chan_mark_dead(sc); 226 } else { 227 if (sc->istate == CHAN_INPUT_OPEN) 228 chan_read_failed(sc); 229 if (sc->ostate == CHAN_OUTPUT_OPEN) 230 chan_write_failed(sc); 231 } 232 } 233 channel_cancel_cleanup(c->self); 234 } 235 236 /* Check mux client environment variables before passing them to mux master. */ 237 static int 238 env_permitted(char *env) 239 { 240 int i, ret; 241 char name[1024], *cp; 242 243 if ((cp = strchr(env, '=')) == NULL || cp == env) 244 return 0; 245 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 246 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 247 error("env_permitted: name '%.100s...' too long", env); 248 return 0; 249 } 250 251 for (i = 0; i < options.num_send_env; i++) 252 if (match_pattern(name, options.send_env[i])) 253 return 1; 254 255 return 0; 256 } 257 258 /* Mux master protocol message handlers */ 259 260 static int 261 process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) 262 { 263 u_int ver; 264 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 265 266 if (state == NULL) 267 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 268 if (state->hello_rcvd) { 269 error("%s: HELLO received twice", __func__); 270 return -1; 271 } 272 if (buffer_get_int_ret(&ver, m) != 0) { 273 malf: 274 error("%s: malformed message", __func__); 275 return -1; 276 } 277 if (ver != SSHMUX_VER) { 278 error("Unsupported multiplexing protocol version %d " 279 "(expected %d)", ver, SSHMUX_VER); 280 return -1; 281 } 282 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 283 284 /* No extensions are presently defined */ 285 while (buffer_len(m) > 0) { 286 char *name = buffer_get_string_ret(m, NULL); 287 char *value = buffer_get_string_ret(m, NULL); 288 289 if (name == NULL || value == NULL) { 290 if (name != NULL) 291 xfree(name); 292 goto malf; 293 } 294 debug2("Unrecognised slave extension \"%s\"", name); 295 xfree(name); 296 xfree(value); 297 } 298 state->hello_rcvd = 1; 299 return 0; 300 } 301 302 static int 303 process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) 304 { 305 Channel *nc; 306 struct mux_session_confirm_ctx *cctx; 307 char *reserved, *cmd, *cp; 308 u_int i, j, len, env_len, escape_char, window, packetmax; 309 int new_fd[3]; 310 311 /* Reply for SSHMUX_COMMAND_OPEN */ 312 cctx = xcalloc(1, sizeof(*cctx)); 313 cctx->term = NULL; 314 cctx->rid = rid; 315 cmd = reserved = NULL; 316 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 317 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 318 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 319 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 320 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 321 buffer_get_int_ret(&escape_char, m) != 0 || 322 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 323 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 324 malf: 325 if (cmd != NULL) 326 xfree(cmd); 327 if (reserved != NULL) 328 xfree(reserved); 329 if (cctx->term != NULL) 330 xfree(cctx->term); 331 error("%s: malformed message", __func__); 332 return -1; 333 } 334 xfree(reserved); 335 reserved = NULL; 336 337 cctx->env = NULL; 338 env_len = 0; 339 while (buffer_len(m) > 0) { 340 #define MUX_MAX_ENV_VARS 4096 341 if ((cp = buffer_get_string_ret(m, &len)) == NULL) { 342 xfree(cmd); 343 goto malf; 344 } 345 if (!env_permitted(cp)) { 346 xfree(cp); 347 continue; 348 } 349 cctx->env = xrealloc(cctx->env, env_len + 2, 350 sizeof(*cctx->env)); 351 cctx->env[env_len++] = cp; 352 cctx->env[env_len] = NULL; 353 if (env_len > MUX_MAX_ENV_VARS) { 354 error(">%d environment variables received, ignoring " 355 "additional", MUX_MAX_ENV_VARS); 356 break; 357 } 358 } 359 360 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 361 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 362 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 363 cctx->want_subsys, cctx->term, cmd, env_len); 364 365 buffer_init(&cctx->cmd); 366 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 367 xfree(cmd); 368 cmd = NULL; 369 370 /* Gather fds from client */ 371 for(i = 0; i < 3; i++) { 372 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 373 error("%s: failed to receive fd %d from slave", 374 __func__, i); 375 for (j = 0; j < i; j++) 376 close(new_fd[j]); 377 for (j = 0; j < env_len; j++) 378 xfree(cctx->env[j]); 379 if (env_len > 0) 380 xfree(cctx->env); 381 xfree(cctx->term); 382 buffer_free(&cctx->cmd); 383 xfree(cctx); 384 385 /* prepare reply */ 386 buffer_put_int(r, MUX_S_FAILURE); 387 buffer_put_int(r, rid); 388 buffer_put_cstring(r, 389 "did not receive file descriptors"); 390 return -1; 391 } 392 } 393 394 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 395 new_fd[0], new_fd[1], new_fd[2]); 396 397 /* XXX support multiple child sessions in future */ 398 if (c->remote_id != -1) { 399 debug2("%s: session already open", __func__); 400 /* prepare reply */ 401 buffer_put_int(r, MUX_S_FAILURE); 402 buffer_put_int(r, rid); 403 buffer_put_cstring(r, "Multiple sessions not supported"); 404 cleanup: 405 close(new_fd[0]); 406 close(new_fd[1]); 407 close(new_fd[2]); 408 xfree(cctx->term); 409 if (env_len != 0) { 410 for (i = 0; i < env_len; i++) 411 xfree(cctx->env[i]); 412 xfree(cctx->env); 413 } 414 buffer_free(&cctx->cmd); 415 return 0; 416 } 417 418 if (options.control_master == SSHCTL_MASTER_ASK || 419 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 420 if (!ask_permission("Allow shared connection to %s? ", host)) { 421 debug2("%s: session refused by user", __func__); 422 /* prepare reply */ 423 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 424 buffer_put_int(r, rid); 425 buffer_put_cstring(r, "Permission denied"); 426 goto cleanup; 427 } 428 } 429 430 /* Try to pick up ttymodes from client before it goes raw */ 431 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 432 error("%s: tcgetattr: %s", __func__, strerror(errno)); 433 434 /* enable nonblocking unless tty */ 435 if (!isatty(new_fd[0])) 436 set_nonblock(new_fd[0]); 437 if (!isatty(new_fd[1])) 438 set_nonblock(new_fd[1]); 439 if (!isatty(new_fd[2])) 440 set_nonblock(new_fd[2]); 441 442 window = CHAN_SES_WINDOW_DEFAULT; 443 packetmax = CHAN_SES_PACKET_DEFAULT; 444 if (cctx->want_tty) { 445 window >>= 1; 446 packetmax >>= 1; 447 } 448 449 nc = channel_new("session", SSH_CHANNEL_OPENING, 450 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 451 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 452 453 nc->ctl_chan = c->self; /* link session -> control channel */ 454 c->remote_id = nc->self; /* link control -> session channel */ 455 456 if (cctx->want_tty && escape_char != 0xffffffff) { 457 channel_register_filter(nc->self, 458 client_simple_escape_filter, NULL, 459 client_filter_cleanup, 460 client_new_escape_filter_ctx((int)escape_char)); 461 } 462 463 debug2("%s: channel_new: %d linked to control channel %d", 464 __func__, nc->self, nc->ctl_chan); 465 466 channel_send_open(nc->self); 467 channel_register_open_confirm(nc->self, mux_session_confirm, cctx); 468 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 469 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 470 471 /* reply is deferred, sent by mux_session_confirm */ 472 return 0; 473 } 474 475 static int 476 process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) 477 { 478 debug2("%s: channel %d: alive check", __func__, c->self); 479 480 /* prepare reply */ 481 buffer_put_int(r, MUX_S_ALIVE); 482 buffer_put_int(r, rid); 483 buffer_put_int(r, (u_int)getpid()); 484 485 return 0; 486 } 487 488 static int 489 process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) 490 { 491 debug2("%s: channel %d: terminate request", __func__, c->self); 492 493 if (options.control_master == SSHCTL_MASTER_ASK || 494 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 495 if (!ask_permission("Terminate shared connection to %s? ", 496 host)) { 497 debug2("%s: termination refused by user", __func__); 498 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 499 buffer_put_int(r, rid); 500 buffer_put_cstring(r, "Permission denied"); 501 return 0; 502 } 503 } 504 505 quit_pending = 1; 506 buffer_put_int(r, MUX_S_OK); 507 buffer_put_int(r, rid); 508 /* XXX exit happens too soon - message never makes it to client */ 509 return 0; 510 } 511 512 static char * 513 format_forward(u_int ftype, Forward *fwd) 514 { 515 char *ret; 516 517 switch (ftype) { 518 case MUX_FWD_LOCAL: 519 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 520 (fwd->listen_host == NULL) ? 521 (options.gateway_ports ? "*" : "LOCALHOST") : 522 fwd->listen_host, fwd->listen_port, 523 fwd->connect_host, fwd->connect_port); 524 break; 525 case MUX_FWD_DYNAMIC: 526 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 527 (fwd->listen_host == NULL) ? 528 (options.gateway_ports ? "*" : "LOCALHOST") : 529 fwd->listen_host, fwd->listen_port); 530 break; 531 case MUX_FWD_REMOTE: 532 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 533 (fwd->listen_host == NULL) ? 534 "LOCALHOST" : fwd->listen_host, 535 fwd->listen_port, 536 fwd->connect_host, fwd->connect_port); 537 break; 538 default: 539 fatal("%s: unknown forward type %u", __func__, ftype); 540 } 541 return ret; 542 } 543 544 static int 545 compare_host(const char *a, const char *b) 546 { 547 if (a == NULL && b == NULL) 548 return 1; 549 if (a == NULL || b == NULL) 550 return 0; 551 return strcmp(a, b) == 0; 552 } 553 554 static int 555 compare_forward(Forward *a, Forward *b) 556 { 557 if (!compare_host(a->listen_host, b->listen_host)) 558 return 0; 559 if (a->listen_port != b->listen_port) 560 return 0; 561 if (!compare_host(a->connect_host, b->connect_host)) 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 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_host, rfwd->connect_port); 592 if (type == SSH2_MSG_REQUEST_SUCCESS) { 593 if (rfwd->listen_port == 0) { 594 rfwd->allocated_port = packet_get_int(); 595 logit("Allocated port %u for mux remote forward" 596 " to %s:%d", rfwd->allocated_port, 597 rfwd->connect_host, rfwd->connect_port); 598 buffer_put_int(&out, MUX_S_REMOTE_PORT); 599 buffer_put_int(&out, fctx->rid); 600 buffer_put_int(&out, rfwd->allocated_port); 601 } else { 602 buffer_put_int(&out, MUX_S_OK); 603 buffer_put_int(&out, fctx->rid); 604 } 605 goto out; 606 } else { 607 xasprintf(&failmsg, "remote port forwarding failed for " 608 "listen port %d", rfwd->listen_port); 609 } 610 fail: 611 error("%s: %s", __func__, failmsg); 612 buffer_put_int(&out, MUX_S_FAILURE); 613 buffer_put_int(&out, fctx->rid); 614 buffer_put_cstring(&out, failmsg); 615 xfree(failmsg); 616 out: 617 buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); 618 buffer_free(&out); 619 if (c->mux_pause <= 0) 620 fatal("%s: mux_pause %d", __func__, c->mux_pause); 621 c->mux_pause = 0; /* start processing messages again */ 622 } 623 624 static int 625 process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 626 { 627 Forward fwd; 628 char *fwd_desc = NULL; 629 u_int ftype; 630 int i, ret = 0, freefwd = 1; 631 632 fwd.listen_host = fwd.connect_host = NULL; 633 if (buffer_get_int_ret(&ftype, m) != 0 || 634 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 635 buffer_get_int_ret(&fwd.listen_port, m) != 0 || 636 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 637 buffer_get_int_ret(&fwd.connect_port, m) != 0) { 638 error("%s: malformed message", __func__); 639 ret = -1; 640 goto out; 641 } 642 643 if (*fwd.listen_host == '\0') { 644 xfree(fwd.listen_host); 645 fwd.listen_host = NULL; 646 } 647 if (*fwd.connect_host == '\0') { 648 xfree(fwd.connect_host); 649 fwd.connect_host = NULL; 650 } 651 652 debug2("%s: channel %d: request %s", __func__, c->self, 653 (fwd_desc = format_forward(ftype, &fwd))); 654 655 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 656 ftype != MUX_FWD_DYNAMIC) { 657 logit("%s: invalid forwarding type %u", __func__, ftype); 658 invalid: 659 if (fwd.listen_host) 660 xfree(fwd.listen_host); 661 if (fwd.connect_host) 662 xfree(fwd.connect_host); 663 buffer_put_int(r, MUX_S_FAILURE); 664 buffer_put_int(r, rid); 665 buffer_put_cstring(r, "Invalid forwarding request"); 666 return 0; 667 } 668 if (fwd.listen_port >= 65536) { 669 logit("%s: invalid listen port %u", __func__, 670 fwd.listen_port); 671 goto invalid; 672 } 673 if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC && 674 ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { 675 logit("%s: invalid connect port %u", __func__, 676 fwd.connect_port); 677 goto invalid; 678 } 679 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) { 680 logit("%s: missing connect host", __func__); 681 goto invalid; 682 } 683 684 /* Skip forwards that have already been requested */ 685 switch (ftype) { 686 case MUX_FWD_LOCAL: 687 case MUX_FWD_DYNAMIC: 688 for (i = 0; i < options.num_local_forwards; i++) { 689 if (compare_forward(&fwd, 690 options.local_forwards + i)) { 691 exists: 692 debug2("%s: found existing forwarding", 693 __func__); 694 buffer_put_int(r, MUX_S_OK); 695 buffer_put_int(r, rid); 696 goto out; 697 } 698 } 699 break; 700 case MUX_FWD_REMOTE: 701 for (i = 0; i < options.num_remote_forwards; i++) { 702 if (compare_forward(&fwd, 703 options.remote_forwards + i)) { 704 if (fwd.listen_port != 0) 705 goto exists; 706 debug2("%s: found allocated port", 707 __func__); 708 buffer_put_int(r, MUX_S_REMOTE_PORT); 709 buffer_put_int(r, rid); 710 buffer_put_int(r, 711 options.remote_forwards[i].allocated_port); 712 goto out; 713 } 714 } 715 break; 716 } 717 718 if (options.control_master == SSHCTL_MASTER_ASK || 719 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 720 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 721 debug2("%s: forwarding refused by user", __func__); 722 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 723 buffer_put_int(r, rid); 724 buffer_put_cstring(r, "Permission denied"); 725 goto out; 726 } 727 } 728 729 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 730 if (channel_setup_local_fwd_listener(fwd.listen_host, 731 fwd.listen_port, fwd.connect_host, fwd.connect_port, 732 options.gateway_ports) < 0) { 733 fail: 734 logit("slave-requested %s failed", fwd_desc); 735 buffer_put_int(r, MUX_S_FAILURE); 736 buffer_put_int(r, rid); 737 buffer_put_cstring(r, "Port forwarding failed"); 738 goto out; 739 } 740 add_local_forward(&options, &fwd); 741 freefwd = 0; 742 } else { 743 struct mux_channel_confirm_ctx *fctx; 744 745 if (channel_request_remote_forwarding(fwd.listen_host, 746 fwd.listen_port, fwd.connect_host, fwd.connect_port) < 0) 747 goto fail; 748 add_remote_forward(&options, &fwd); 749 fctx = xcalloc(1, sizeof(*fctx)); 750 fctx->cid = c->self; 751 fctx->rid = rid; 752 fctx->fid = options.num_remote_forwards - 1; 753 client_register_global_confirm(mux_confirm_remote_forward, 754 fctx); 755 freefwd = 0; 756 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 757 /* delayed reply in mux_confirm_remote_forward */ 758 goto out; 759 } 760 buffer_put_int(r, MUX_S_OK); 761 buffer_put_int(r, rid); 762 out: 763 if (fwd_desc != NULL) 764 xfree(fwd_desc); 765 if (freefwd) { 766 if (fwd.listen_host != NULL) 767 xfree(fwd.listen_host); 768 if (fwd.connect_host != NULL) 769 xfree(fwd.connect_host); 770 } 771 return ret; 772 } 773 774 static int 775 process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 776 { 777 Forward fwd; 778 char *fwd_desc = NULL; 779 u_int ftype; 780 int ret = 0; 781 782 fwd.listen_host = fwd.connect_host = NULL; 783 if (buffer_get_int_ret(&ftype, m) != 0 || 784 (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || 785 buffer_get_int_ret(&fwd.listen_port, m) != 0 || 786 (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || 787 buffer_get_int_ret(&fwd.connect_port, m) != 0) { 788 error("%s: malformed message", __func__); 789 ret = -1; 790 goto out; 791 } 792 793 if (*fwd.listen_host == '\0') { 794 xfree(fwd.listen_host); 795 fwd.listen_host = NULL; 796 } 797 if (*fwd.connect_host == '\0') { 798 xfree(fwd.connect_host); 799 fwd.connect_host = NULL; 800 } 801 802 debug2("%s: channel %d: request %s", __func__, c->self, 803 (fwd_desc = format_forward(ftype, &fwd))); 804 805 /* XXX implement this */ 806 buffer_put_int(r, MUX_S_FAILURE); 807 buffer_put_int(r, rid); 808 buffer_put_cstring(r, "unimplemented"); 809 810 out: 811 if (fwd_desc != NULL) 812 xfree(fwd_desc); 813 if (fwd.listen_host != NULL) 814 xfree(fwd.listen_host); 815 if (fwd.connect_host != NULL) 816 xfree(fwd.connect_host); 817 818 return ret; 819 } 820 821 static int 822 process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) 823 { 824 Channel *nc; 825 char *reserved, *chost; 826 u_int cport, i, j; 827 int new_fd[2]; 828 829 chost = reserved = NULL; 830 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 831 (chost = buffer_get_string_ret(m, NULL)) == NULL || 832 buffer_get_int_ret(&cport, m) != 0) { 833 if (reserved != NULL) 834 xfree(reserved); 835 if (chost != NULL) 836 xfree(chost); 837 error("%s: malformed message", __func__); 838 return -1; 839 } 840 xfree(reserved); 841 842 debug2("%s: channel %d: request stdio fwd to %s:%u", 843 __func__, c->self, chost, cport); 844 845 /* Gather fds from client */ 846 for(i = 0; i < 2; i++) { 847 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 848 error("%s: failed to receive fd %d from slave", 849 __func__, i); 850 for (j = 0; j < i; j++) 851 close(new_fd[j]); 852 xfree(chost); 853 854 /* prepare reply */ 855 buffer_put_int(r, MUX_S_FAILURE); 856 buffer_put_int(r, rid); 857 buffer_put_cstring(r, 858 "did not receive file descriptors"); 859 return -1; 860 } 861 } 862 863 debug3("%s: got fds stdin %d, stdout %d", __func__, 864 new_fd[0], new_fd[1]); 865 866 /* XXX support multiple child sessions in future */ 867 if (c->remote_id != -1) { 868 debug2("%s: session already open", __func__); 869 /* prepare reply */ 870 buffer_put_int(r, MUX_S_FAILURE); 871 buffer_put_int(r, rid); 872 buffer_put_cstring(r, "Multiple sessions not supported"); 873 cleanup: 874 close(new_fd[0]); 875 close(new_fd[1]); 876 xfree(chost); 877 return 0; 878 } 879 880 if (options.control_master == SSHCTL_MASTER_ASK || 881 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 882 if (!ask_permission("Allow forward to %s:%u? ", 883 chost, cport)) { 884 debug2("%s: stdio fwd refused by user", __func__); 885 /* prepare reply */ 886 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 887 buffer_put_int(r, rid); 888 buffer_put_cstring(r, "Permission denied"); 889 goto cleanup; 890 } 891 } 892 893 /* enable nonblocking unless tty */ 894 if (!isatty(new_fd[0])) 895 set_nonblock(new_fd[0]); 896 if (!isatty(new_fd[1])) 897 set_nonblock(new_fd[1]); 898 899 nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); 900 901 nc->ctl_chan = c->self; /* link session -> control channel */ 902 c->remote_id = nc->self; /* link control -> session channel */ 903 904 debug2("%s: channel_new: %d linked to control channel %d", 905 __func__, nc->self, nc->ctl_chan); 906 907 channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); 908 909 /* prepare reply */ 910 /* XXX defer until channel confirmed */ 911 buffer_put_int(r, MUX_S_SESSION_OPENED); 912 buffer_put_int(r, rid); 913 buffer_put_int(r, nc->self); 914 915 return 0; 916 } 917 918 /* Channel callbacks fired on read/write from mux slave fd */ 919 static int 920 mux_master_read_cb(Channel *c) 921 { 922 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 923 Buffer in, out; 924 void *ptr; 925 u_int type, rid, have, i; 926 int ret = -1; 927 928 /* Setup ctx and */ 929 if (c->mux_ctx == NULL) { 930 state = xcalloc(1, sizeof(*state)); 931 c->mux_ctx = state; 932 channel_register_cleanup(c->self, 933 mux_master_control_cleanup_cb, 0); 934 935 /* Send hello */ 936 buffer_init(&out); 937 buffer_put_int(&out, MUX_MSG_HELLO); 938 buffer_put_int(&out, SSHMUX_VER); 939 /* no extensions */ 940 buffer_put_string(&c->output, buffer_ptr(&out), 941 buffer_len(&out)); 942 buffer_free(&out); 943 debug3("%s: channel %d: hello sent", __func__, c->self); 944 return 0; 945 } 946 947 buffer_init(&in); 948 buffer_init(&out); 949 950 /* Channel code ensures that we receive whole packets */ 951 if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { 952 malf: 953 error("%s: malformed message", __func__); 954 goto out; 955 } 956 buffer_append(&in, ptr, have); 957 958 if (buffer_get_int_ret(&type, &in) != 0) 959 goto malf; 960 debug3("%s: channel %d packet type 0x%08x len %u", 961 __func__, c->self, type, buffer_len(&in)); 962 963 if (type == MUX_MSG_HELLO) 964 rid = 0; 965 else { 966 if (!state->hello_rcvd) { 967 error("%s: expected MUX_MSG_HELLO(0x%08x), " 968 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 969 goto out; 970 } 971 if (buffer_get_int_ret(&rid, &in) != 0) 972 goto malf; 973 } 974 975 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 976 if (type == mux_master_handlers[i].type) { 977 ret = mux_master_handlers[i].handler(rid, c, &in, &out); 978 break; 979 } 980 } 981 if (mux_master_handlers[i].handler == NULL) { 982 error("%s: unsupported mux message 0x%08x", __func__, type); 983 buffer_put_int(&out, MUX_S_FAILURE); 984 buffer_put_int(&out, rid); 985 buffer_put_cstring(&out, "unsupported request"); 986 ret = 0; 987 } 988 /* Enqueue reply packet */ 989 if (buffer_len(&out) != 0) { 990 buffer_put_string(&c->output, buffer_ptr(&out), 991 buffer_len(&out)); 992 } 993 out: 994 buffer_free(&in); 995 buffer_free(&out); 996 return ret; 997 } 998 999 void 1000 mux_exit_message(Channel *c, int exitval) 1001 { 1002 Buffer m; 1003 Channel *mux_chan; 1004 1005 debug3("%s: channel %d: exit message, evitval %d", __func__, c->self, 1006 exitval); 1007 1008 if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) 1009 fatal("%s: channel %d missing mux channel %d", 1010 __func__, c->self, c->ctl_chan); 1011 1012 /* Append exit message packet to control socket output queue */ 1013 buffer_init(&m); 1014 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1015 buffer_put_int(&m, c->self); 1016 buffer_put_int(&m, exitval); 1017 1018 buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1019 buffer_free(&m); 1020 } 1021 1022 /* Prepare a mux master to listen on a Unix domain socket. */ 1023 void 1024 muxserver_listen(void) 1025 { 1026 struct sockaddr_un addr; 1027 socklen_t sun_len; 1028 mode_t old_umask; 1029 char *orig_control_path = options.control_path; 1030 char rbuf[16+1]; 1031 u_int i, r; 1032 1033 if (options.control_path == NULL || 1034 options.control_master == SSHCTL_MASTER_NO) 1035 return; 1036 1037 debug("setting up multiplex master socket"); 1038 1039 /* 1040 * Use a temporary path before listen so we can pseudo-atomically 1041 * establish the listening socket in its final location to avoid 1042 * other processes racing in between bind() and listen() and hitting 1043 * an unready socket. 1044 */ 1045 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1046 r = arc4random_uniform(26+26+10); 1047 rbuf[i] = (r < 26) ? 'a' + r : 1048 (r < 26*2) ? 'A' + r - 26 : 1049 '0' + r - 26 - 26; 1050 } 1051 rbuf[sizeof(rbuf) - 1] = '\0'; 1052 options.control_path = NULL; 1053 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1054 debug3("%s: temporary control path %s", __func__, options.control_path); 1055 1056 memset(&addr, '\0', sizeof(addr)); 1057 addr.sun_family = AF_UNIX; 1058 sun_len = offsetof(struct sockaddr_un, sun_path) + 1059 strlen(options.control_path) + 1; 1060 1061 if (strlcpy(addr.sun_path, options.control_path, 1062 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 1063 fatal("ControlPath too long"); 1064 1065 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1066 fatal("%s socket(): %s", __func__, strerror(errno)); 1067 1068 old_umask = umask(0177); 1069 if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) { 1070 muxserver_sock = -1; 1071 if (errno == EINVAL || errno == EADDRINUSE) { 1072 error("ControlSocket %s already exists, " 1073 "disabling multiplexing", options.control_path); 1074 disable_mux_master: 1075 close(muxserver_sock); 1076 muxserver_sock = -1; 1077 xfree(options.control_path); 1078 options.control_path = NULL; 1079 options.control_master = SSHCTL_MASTER_NO; 1080 return; 1081 } else 1082 fatal("%s bind(): %s", __func__, strerror(errno)); 1083 } 1084 umask(old_umask); 1085 1086 if (listen(muxserver_sock, 64) == -1) 1087 fatal("%s listen(): %s", __func__, strerror(errno)); 1088 1089 /* Now atomically "move" the mux socket into position */ 1090 if (link(options.control_path, orig_control_path) != 0) { 1091 if (errno != EEXIST) { 1092 fatal("%s: link mux listener %s => %s: %s", __func__, 1093 options.control_path, orig_control_path, 1094 strerror(errno)); 1095 } 1096 error("ControlSocket %s already exists, disabling multiplexing", 1097 orig_control_path); 1098 xfree(orig_control_path); 1099 unlink(options.control_path); 1100 goto disable_mux_master; 1101 } 1102 unlink(options.control_path); 1103 xfree(options.control_path); 1104 options.control_path = orig_control_path; 1105 1106 set_nonblock(muxserver_sock); 1107 1108 mux_listener_channel = channel_new("mux listener", 1109 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1110 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1111 0, options.control_path, 1); 1112 mux_listener_channel->mux_rcb = mux_master_read_cb; 1113 debug3("%s: mux listener channel %d fd %d", __func__, 1114 mux_listener_channel->self, mux_listener_channel->sock); 1115 } 1116 1117 /* Callback on open confirmation in mux master for a mux client session. */ 1118 static void 1119 mux_session_confirm(int id, int success, void *arg) 1120 { 1121 struct mux_session_confirm_ctx *cctx = arg; 1122 const char *display; 1123 Channel *c, *cc; 1124 int i; 1125 Buffer reply; 1126 1127 if (cctx == NULL) 1128 fatal("%s: cctx == NULL", __func__); 1129 if ((c = channel_by_id(id)) == NULL) 1130 fatal("%s: no channel for id %d", __func__, id); 1131 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1132 fatal("%s: channel %d lacks control channel %d", __func__, 1133 id, c->ctl_chan); 1134 1135 if (!success) { 1136 debug3("%s: sending failure reply", __func__); 1137 /* prepare reply */ 1138 buffer_init(&reply); 1139 buffer_put_int(&reply, MUX_S_FAILURE); 1140 buffer_put_int(&reply, cctx->rid); 1141 buffer_put_cstring(&reply, "Session open refused by peer"); 1142 goto done; 1143 } 1144 1145 display = getenv("DISPLAY"); 1146 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1147 char *proto, *data; 1148 1149 /* Get reasonable local authentication information. */ 1150 client_x11_get_proto(display, options.xauth_location, 1151 options.forward_x11_trusted, options.forward_x11_timeout, 1152 &proto, &data); 1153 /* Request forwarding with authentication spoofing. */ 1154 debug("Requesting X11 forwarding with authentication " 1155 "spoofing."); 1156 x11_request_forwarding_with_spoofing(id, display, proto, data); 1157 /* XXX wait for reply */ 1158 } 1159 1160 if (cctx->want_agent_fwd && options.forward_agent) { 1161 debug("Requesting authentication agent forwarding."); 1162 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1163 packet_send(); 1164 } 1165 1166 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1167 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1168 1169 debug3("%s: sending success reply", __func__); 1170 /* prepare reply */ 1171 buffer_init(&reply); 1172 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1173 buffer_put_int(&reply, cctx->rid); 1174 buffer_put_int(&reply, c->self); 1175 1176 done: 1177 /* Send reply */ 1178 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1179 buffer_free(&reply); 1180 1181 if (cc->mux_pause <= 0) 1182 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1183 cc->mux_pause = 0; /* start processing messages again */ 1184 c->open_confirm_ctx = NULL; 1185 buffer_free(&cctx->cmd); 1186 xfree(cctx->term); 1187 if (cctx->env != NULL) { 1188 for (i = 0; cctx->env[i] != NULL; i++) 1189 xfree(cctx->env[i]); 1190 xfree(cctx->env); 1191 } 1192 xfree(cctx); 1193 } 1194 1195 /* ** Multiplexing client support */ 1196 1197 /* Exit signal handler */ 1198 static void 1199 control_client_sighandler(int signo) 1200 { 1201 muxclient_terminate = signo; 1202 } 1203 1204 /* 1205 * Relay signal handler - used to pass some signals from mux client to 1206 * mux master. 1207 */ 1208 static void 1209 control_client_sigrelay(int signo) 1210 { 1211 int save_errno = errno; 1212 1213 if (muxserver_pid > 1) 1214 kill(muxserver_pid, signo); 1215 1216 errno = save_errno; 1217 } 1218 1219 static int 1220 mux_client_read(int fd, Buffer *b, u_int need) 1221 { 1222 u_int have; 1223 ssize_t len; 1224 u_char *p; 1225 struct pollfd pfd; 1226 1227 pfd.fd = fd; 1228 pfd.events = POLLIN; 1229 p = buffer_append_space(b, need); 1230 for (have = 0; have < need; ) { 1231 if (muxclient_terminate) { 1232 errno = EINTR; 1233 return -1; 1234 } 1235 len = read(fd, p + have, need - have); 1236 if (len < 0) { 1237 switch (errno) { 1238 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1239 case EWOULDBLOCK: 1240 #endif 1241 case EAGAIN: 1242 (void)poll(&pfd, 1, -1); 1243 /* FALLTHROUGH */ 1244 case EINTR: 1245 continue; 1246 default: 1247 return -1; 1248 } 1249 } 1250 if (len == 0) { 1251 errno = EPIPE; 1252 return -1; 1253 } 1254 have += (u_int)len; 1255 } 1256 return 0; 1257 } 1258 1259 static int 1260 mux_client_write_packet(int fd, Buffer *m) 1261 { 1262 Buffer queue; 1263 u_int have, need; 1264 int oerrno, len; 1265 u_char *ptr; 1266 struct pollfd pfd; 1267 1268 pfd.fd = fd; 1269 pfd.events = POLLOUT; 1270 buffer_init(&queue); 1271 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1272 1273 need = buffer_len(&queue); 1274 ptr = buffer_ptr(&queue); 1275 1276 for (have = 0; have < need; ) { 1277 if (muxclient_terminate) { 1278 buffer_free(&queue); 1279 errno = EINTR; 1280 return -1; 1281 } 1282 len = write(fd, ptr + have, need - have); 1283 if (len < 0) { 1284 switch (errno) { 1285 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1286 case EWOULDBLOCK: 1287 #endif 1288 case EAGAIN: 1289 (void)poll(&pfd, 1, -1); 1290 /* FALLTHROUGH */ 1291 case EINTR: 1292 continue; 1293 default: 1294 oerrno = errno; 1295 buffer_free(&queue); 1296 errno = oerrno; 1297 return -1; 1298 } 1299 } 1300 if (len == 0) { 1301 buffer_free(&queue); 1302 errno = EPIPE; 1303 return -1; 1304 } 1305 have += (u_int)len; 1306 } 1307 buffer_free(&queue); 1308 return 0; 1309 } 1310 1311 static int 1312 mux_client_read_packet(int fd, Buffer *m) 1313 { 1314 Buffer queue; 1315 u_int need, have; 1316 void *ptr; 1317 int oerrno; 1318 1319 buffer_init(&queue); 1320 if (mux_client_read(fd, &queue, 4) != 0) { 1321 if ((oerrno = errno) == EPIPE) 1322 debug3("%s: read header failed: %s", __func__, strerror(errno)); 1323 errno = oerrno; 1324 return -1; 1325 } 1326 need = get_u32(buffer_ptr(&queue)); 1327 if (mux_client_read(fd, &queue, need) != 0) { 1328 oerrno = errno; 1329 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1330 errno = oerrno; 1331 return -1; 1332 } 1333 ptr = buffer_get_string_ptr(&queue, &have); 1334 buffer_append(m, ptr, have); 1335 buffer_free(&queue); 1336 return 0; 1337 } 1338 1339 static int 1340 mux_client_hello_exchange(int fd) 1341 { 1342 Buffer m; 1343 u_int type, ver; 1344 1345 buffer_init(&m); 1346 buffer_put_int(&m, MUX_MSG_HELLO); 1347 buffer_put_int(&m, SSHMUX_VER); 1348 /* no extensions */ 1349 1350 if (mux_client_write_packet(fd, &m) != 0) 1351 fatal("%s: write packet: %s", __func__, strerror(errno)); 1352 1353 buffer_clear(&m); 1354 1355 /* Read their HELLO */ 1356 if (mux_client_read_packet(fd, &m) != 0) { 1357 buffer_free(&m); 1358 return -1; 1359 } 1360 1361 type = buffer_get_int(&m); 1362 if (type != MUX_MSG_HELLO) 1363 fatal("%s: expected HELLO (%u) received %u", 1364 __func__, MUX_MSG_HELLO, type); 1365 ver = buffer_get_int(&m); 1366 if (ver != SSHMUX_VER) 1367 fatal("Unsupported multiplexing protocol version %d " 1368 "(expected %d)", ver, SSHMUX_VER); 1369 debug2("%s: master version %u", __func__, ver); 1370 /* No extensions are presently defined */ 1371 while (buffer_len(&m) > 0) { 1372 char *name = buffer_get_string(&m, NULL); 1373 char *value = buffer_get_string(&m, NULL); 1374 1375 debug2("Unrecognised master extension \"%s\"", name); 1376 xfree(name); 1377 xfree(value); 1378 } 1379 buffer_free(&m); 1380 return 0; 1381 } 1382 1383 static u_int 1384 mux_client_request_alive(int fd) 1385 { 1386 Buffer m; 1387 char *e; 1388 u_int pid, type, rid; 1389 1390 debug3("%s: entering", __func__); 1391 1392 buffer_init(&m); 1393 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1394 buffer_put_int(&m, muxclient_request_id); 1395 1396 if (mux_client_write_packet(fd, &m) != 0) 1397 fatal("%s: write packet: %s", __func__, strerror(errno)); 1398 1399 buffer_clear(&m); 1400 1401 /* Read their reply */ 1402 if (mux_client_read_packet(fd, &m) != 0) { 1403 buffer_free(&m); 1404 return 0; 1405 } 1406 1407 type = buffer_get_int(&m); 1408 if (type != MUX_S_ALIVE) { 1409 e = buffer_get_string(&m, NULL); 1410 fatal("%s: master returned error: %s", __func__, e); 1411 } 1412 1413 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1414 fatal("%s: out of sequence reply: my id %u theirs %u", 1415 __func__, muxclient_request_id, rid); 1416 pid = buffer_get_int(&m); 1417 buffer_free(&m); 1418 1419 debug3("%s: done pid = %u", __func__, pid); 1420 1421 muxclient_request_id++; 1422 1423 return pid; 1424 } 1425 1426 static void 1427 mux_client_request_terminate(int fd) 1428 { 1429 Buffer m; 1430 char *e; 1431 u_int type, rid; 1432 1433 debug3("%s: entering", __func__); 1434 1435 buffer_init(&m); 1436 buffer_put_int(&m, MUX_C_TERMINATE); 1437 buffer_put_int(&m, muxclient_request_id); 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 /* Remote end exited already */ 1447 if (errno == EPIPE) { 1448 buffer_free(&m); 1449 return; 1450 } 1451 fatal("%s: read from master failed: %s", 1452 __func__, strerror(errno)); 1453 } 1454 1455 type = buffer_get_int(&m); 1456 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1457 fatal("%s: out of sequence reply: my id %u theirs %u", 1458 __func__, muxclient_request_id, rid); 1459 switch (type) { 1460 case MUX_S_OK: 1461 break; 1462 case MUX_S_PERMISSION_DENIED: 1463 e = buffer_get_string(&m, NULL); 1464 fatal("Master refused termination request: %s", e); 1465 case MUX_S_FAILURE: 1466 e = buffer_get_string(&m, NULL); 1467 fatal("%s: termination request failed: %s", __func__, e); 1468 default: 1469 fatal("%s: unexpected response from master 0x%08x", 1470 __func__, type); 1471 } 1472 buffer_free(&m); 1473 muxclient_request_id++; 1474 } 1475 1476 static int 1477 mux_client_request_forward(int fd, u_int ftype, Forward *fwd) 1478 { 1479 Buffer m; 1480 char *e, *fwd_desc; 1481 u_int type, rid; 1482 1483 fwd_desc = format_forward(ftype, fwd); 1484 debug("Requesting %s", fwd_desc); 1485 xfree(fwd_desc); 1486 1487 buffer_init(&m); 1488 buffer_put_int(&m, MUX_C_OPEN_FWD); 1489 buffer_put_int(&m, muxclient_request_id); 1490 buffer_put_int(&m, ftype); 1491 buffer_put_cstring(&m, 1492 fwd->listen_host == NULL ? "" : fwd->listen_host); 1493 buffer_put_int(&m, fwd->listen_port); 1494 buffer_put_cstring(&m, 1495 fwd->connect_host == NULL ? "" : fwd->connect_host); 1496 buffer_put_int(&m, fwd->connect_port); 1497 1498 if (mux_client_write_packet(fd, &m) != 0) 1499 fatal("%s: write packet: %s", __func__, strerror(errno)); 1500 1501 buffer_clear(&m); 1502 1503 /* Read their reply */ 1504 if (mux_client_read_packet(fd, &m) != 0) { 1505 buffer_free(&m); 1506 return -1; 1507 } 1508 1509 type = buffer_get_int(&m); 1510 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1511 fatal("%s: out of sequence reply: my id %u theirs %u", 1512 __func__, muxclient_request_id, rid); 1513 switch (type) { 1514 case MUX_S_OK: 1515 break; 1516 case MUX_S_REMOTE_PORT: 1517 fwd->allocated_port = buffer_get_int(&m); 1518 logit("Allocated port %u for remote forward to %s:%d", 1519 fwd->allocated_port, 1520 fwd->connect_host ? fwd->connect_host : "", 1521 fwd->connect_port); 1522 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1523 fprintf(stdout, "%u\n", fwd->allocated_port); 1524 break; 1525 case MUX_S_PERMISSION_DENIED: 1526 e = buffer_get_string(&m, NULL); 1527 buffer_free(&m); 1528 error("Master refused forwarding request: %s", e); 1529 return -1; 1530 case MUX_S_FAILURE: 1531 e = buffer_get_string(&m, NULL); 1532 buffer_free(&m); 1533 error("%s: forwarding request failed: %s", __func__, e); 1534 return -1; 1535 default: 1536 fatal("%s: unexpected response from master 0x%08x", 1537 __func__, type); 1538 } 1539 buffer_free(&m); 1540 1541 muxclient_request_id++; 1542 return 0; 1543 } 1544 1545 static int 1546 mux_client_request_forwards(int fd) 1547 { 1548 int i; 1549 1550 debug3("%s: requesting forwardings: %d local, %d remote", __func__, 1551 options.num_local_forwards, options.num_remote_forwards); 1552 1553 /* XXX ExitOnForwardingFailure */ 1554 for (i = 0; i < options.num_local_forwards; i++) { 1555 if (mux_client_request_forward(fd, 1556 options.local_forwards[i].connect_port == 0 ? 1557 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1558 options.local_forwards + i) != 0) 1559 return -1; 1560 } 1561 for (i = 0; i < options.num_remote_forwards; i++) { 1562 if (mux_client_request_forward(fd, MUX_FWD_REMOTE, 1563 options.remote_forwards + i) != 0) 1564 return -1; 1565 } 1566 return 0; 1567 } 1568 1569 static int 1570 mux_client_request_session(int fd) 1571 { 1572 Buffer m; 1573 char *e, *term; 1574 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1575 extern char **environ; 1576 int devnull; 1577 1578 debug3("%s: entering", __func__); 1579 1580 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1581 error("%s: master alive request failed", __func__); 1582 return -1; 1583 } 1584 1585 signal(SIGPIPE, SIG_IGN); 1586 1587 if (stdin_null_flag) { 1588 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1589 fatal("open(/dev/null): %s", strerror(errno)); 1590 if (dup2(devnull, STDIN_FILENO) == -1) 1591 fatal("dup2: %s", strerror(errno)); 1592 if (devnull > STDERR_FILENO) 1593 close(devnull); 1594 } 1595 1596 term = getenv("TERM"); 1597 1598 buffer_init(&m); 1599 buffer_put_int(&m, MUX_C_NEW_SESSION); 1600 buffer_put_int(&m, muxclient_request_id); 1601 buffer_put_cstring(&m, ""); /* reserved */ 1602 buffer_put_int(&m, tty_flag); 1603 buffer_put_int(&m, options.forward_x11); 1604 buffer_put_int(&m, options.forward_agent); 1605 buffer_put_int(&m, subsystem_flag); 1606 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1607 0xffffffff : (u_int)options.escape_char); 1608 buffer_put_cstring(&m, term == NULL ? "" : term); 1609 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1610 1611 if (options.num_send_env > 0 && environ != NULL) { 1612 /* Pass environment */ 1613 for (i = 0; environ[i] != NULL; i++) { 1614 if (env_permitted(environ[i])) { 1615 buffer_put_cstring(&m, environ[i]); 1616 } 1617 } 1618 } 1619 1620 if (mux_client_write_packet(fd, &m) != 0) 1621 fatal("%s: write packet: %s", __func__, strerror(errno)); 1622 1623 /* Send the stdio file descriptors */ 1624 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1625 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1626 mm_send_fd(fd, STDERR_FILENO) == -1) 1627 fatal("%s: send fds failed", __func__); 1628 1629 debug3("%s: session request sent", __func__); 1630 1631 /* Read their reply */ 1632 buffer_clear(&m); 1633 if (mux_client_read_packet(fd, &m) != 0) { 1634 error("%s: read from master failed: %s", 1635 __func__, strerror(errno)); 1636 buffer_free(&m); 1637 return -1; 1638 } 1639 1640 type = buffer_get_int(&m); 1641 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1642 fatal("%s: out of sequence reply: my id %u theirs %u", 1643 __func__, muxclient_request_id, rid); 1644 switch (type) { 1645 case MUX_S_SESSION_OPENED: 1646 sid = buffer_get_int(&m); 1647 debug("%s: master session id: %u", __func__, sid); 1648 break; 1649 case MUX_S_PERMISSION_DENIED: 1650 e = buffer_get_string(&m, NULL); 1651 buffer_free(&m); 1652 error("Master refused session request: %s", e); 1653 return -1; 1654 case MUX_S_FAILURE: 1655 e = buffer_get_string(&m, NULL); 1656 buffer_free(&m); 1657 error("%s: session request failed: %s", __func__, e); 1658 return -1; 1659 default: 1660 buffer_free(&m); 1661 error("%s: unexpected response from master 0x%08x", 1662 __func__, type); 1663 return -1; 1664 } 1665 muxclient_request_id++; 1666 1667 signal(SIGHUP, control_client_sighandler); 1668 signal(SIGINT, control_client_sighandler); 1669 signal(SIGTERM, control_client_sighandler); 1670 signal(SIGWINCH, control_client_sigrelay); 1671 1672 if (tty_flag) 1673 enter_raw_mode(force_tty_flag); 1674 1675 /* 1676 * Stick around until the controlee closes the client_fd. 1677 * Before it does, it is expected to write an exit message. 1678 * This process must read the value and wait for the closure of 1679 * the client_fd; if this one closes early, the multiplex master will 1680 * terminate early too (possibly losing data). 1681 */ 1682 for (exitval = 255, exitval_seen = 0;;) { 1683 buffer_clear(&m); 1684 if (mux_client_read_packet(fd, &m) != 0) 1685 break; 1686 type = buffer_get_int(&m); 1687 if (type != MUX_S_EXIT_MESSAGE) { 1688 e = buffer_get_string(&m, NULL); 1689 fatal("%s: master returned error: %s", __func__, e); 1690 } 1691 if ((esid = buffer_get_int(&m)) != sid) 1692 fatal("%s: exit on unknown session: my id %u theirs %u", 1693 __func__, sid, esid); 1694 debug("%s: master session id: %u", __func__, sid); 1695 if (exitval_seen) 1696 fatal("%s: exitval sent twice", __func__); 1697 exitval = buffer_get_int(&m); 1698 exitval_seen = 1; 1699 } 1700 1701 close(fd); 1702 leave_raw_mode(force_tty_flag); 1703 1704 if (muxclient_terminate) { 1705 debug2("Exiting on signal %d", muxclient_terminate); 1706 exitval = 255; 1707 } else if (!exitval_seen) { 1708 debug2("Control master terminated unexpectedly"); 1709 exitval = 255; 1710 } else 1711 debug2("Received exit status from master %d", exitval); 1712 1713 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1714 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1715 1716 exit(exitval); 1717 } 1718 1719 static int 1720 mux_client_request_stdio_fwd(int fd) 1721 { 1722 Buffer m; 1723 char *e; 1724 u_int type, rid, sid; 1725 int devnull; 1726 1727 debug3("%s: entering", __func__); 1728 1729 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1730 error("%s: master alive request failed", __func__); 1731 return -1; 1732 } 1733 1734 signal(SIGPIPE, SIG_IGN); 1735 1736 if (stdin_null_flag) { 1737 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1738 fatal("open(/dev/null): %s", strerror(errno)); 1739 if (dup2(devnull, STDIN_FILENO) == -1) 1740 fatal("dup2: %s", strerror(errno)); 1741 if (devnull > STDERR_FILENO) 1742 close(devnull); 1743 } 1744 1745 buffer_init(&m); 1746 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1747 buffer_put_int(&m, muxclient_request_id); 1748 buffer_put_cstring(&m, ""); /* reserved */ 1749 buffer_put_cstring(&m, stdio_forward_host); 1750 buffer_put_int(&m, stdio_forward_port); 1751 1752 if (mux_client_write_packet(fd, &m) != 0) 1753 fatal("%s: write packet: %s", __func__, strerror(errno)); 1754 1755 /* Send the stdio file descriptors */ 1756 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1757 mm_send_fd(fd, STDOUT_FILENO) == -1) 1758 fatal("%s: send fds failed", __func__); 1759 1760 debug3("%s: stdio forward request sent", __func__); 1761 1762 /* Read their reply */ 1763 buffer_clear(&m); 1764 1765 if (mux_client_read_packet(fd, &m) != 0) { 1766 error("%s: read from master failed: %s", 1767 __func__, strerror(errno)); 1768 buffer_free(&m); 1769 return -1; 1770 } 1771 1772 type = buffer_get_int(&m); 1773 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1774 fatal("%s: out of sequence reply: my id %u theirs %u", 1775 __func__, muxclient_request_id, rid); 1776 switch (type) { 1777 case MUX_S_SESSION_OPENED: 1778 sid = buffer_get_int(&m); 1779 debug("%s: master session id: %u", __func__, sid); 1780 break; 1781 case MUX_S_PERMISSION_DENIED: 1782 e = buffer_get_string(&m, NULL); 1783 buffer_free(&m); 1784 fatal("Master refused stdio forwarding request: %s", e); 1785 case MUX_S_FAILURE: 1786 e = buffer_get_string(&m, NULL); 1787 buffer_free(&m); 1788 fatal("%s: stdio forwarding request failed: %s", __func__, e); 1789 default: 1790 buffer_free(&m); 1791 error("%s: unexpected response from master 0x%08x", 1792 __func__, type); 1793 return -1; 1794 } 1795 muxclient_request_id++; 1796 1797 signal(SIGHUP, control_client_sighandler); 1798 signal(SIGINT, control_client_sighandler); 1799 signal(SIGTERM, control_client_sighandler); 1800 signal(SIGWINCH, control_client_sigrelay); 1801 1802 /* 1803 * Stick around until the controlee closes the client_fd. 1804 */ 1805 buffer_clear(&m); 1806 if (mux_client_read_packet(fd, &m) != 0) { 1807 if (errno == EPIPE || 1808 (errno == EINTR && muxclient_terminate != 0)) 1809 return 0; 1810 fatal("%s: mux_client_read_packet: %s", 1811 __func__, strerror(errno)); 1812 } 1813 fatal("%s: master returned unexpected message %u", __func__, type); 1814 } 1815 1816 /* Multiplex client main loop. */ 1817 void 1818 muxclient(const char *path) 1819 { 1820 struct sockaddr_un addr; 1821 socklen_t sun_len; 1822 int sock; 1823 u_int pid; 1824 1825 if (muxclient_command == 0) { 1826 if (stdio_forward_host != NULL) 1827 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 1828 else 1829 muxclient_command = SSHMUX_COMMAND_OPEN; 1830 } 1831 1832 switch (options.control_master) { 1833 case SSHCTL_MASTER_AUTO: 1834 case SSHCTL_MASTER_AUTO_ASK: 1835 debug("auto-mux: Trying existing master"); 1836 /* FALLTHROUGH */ 1837 case SSHCTL_MASTER_NO: 1838 break; 1839 default: 1840 return; 1841 } 1842 1843 memset(&addr, '\0', sizeof(addr)); 1844 addr.sun_family = AF_UNIX; 1845 sun_len = offsetof(struct sockaddr_un, sun_path) + 1846 strlen(path) + 1; 1847 1848 if (strlcpy(addr.sun_path, path, 1849 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 1850 fatal("ControlPath too long"); 1851 1852 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1853 fatal("%s socket(): %s", __func__, strerror(errno)); 1854 1855 if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { 1856 switch (muxclient_command) { 1857 case SSHMUX_COMMAND_OPEN: 1858 case SSHMUX_COMMAND_STDIO_FWD: 1859 break; 1860 default: 1861 fatal("Control socket connect(%.100s): %s", path, 1862 strerror(errno)); 1863 } 1864 if (errno == ECONNREFUSED && 1865 options.control_master != SSHCTL_MASTER_NO) { 1866 debug("Stale control socket %.100s, unlinking", path); 1867 unlink(path); 1868 } else if (errno == ENOENT) { 1869 debug("Control socket \"%.100s\" does not exist", path); 1870 } else { 1871 error("Control socket connect(%.100s): %s", path, 1872 strerror(errno)); 1873 } 1874 close(sock); 1875 return; 1876 } 1877 set_nonblock(sock); 1878 1879 if (mux_client_hello_exchange(sock) != 0) { 1880 error("%s: master hello exchange failed", __func__); 1881 close(sock); 1882 return; 1883 } 1884 1885 switch (muxclient_command) { 1886 case SSHMUX_COMMAND_ALIVE_CHECK: 1887 if ((pid = mux_client_request_alive(sock)) == 0) 1888 fatal("%s: master alive check failed", __func__); 1889 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 1890 exit(0); 1891 case SSHMUX_COMMAND_TERMINATE: 1892 mux_client_request_terminate(sock); 1893 fprintf(stderr, "Exit request sent.\r\n"); 1894 exit(0); 1895 case SSHMUX_COMMAND_FORWARD: 1896 if (mux_client_request_forwards(sock) != 0) 1897 fatal("%s: master forward request failed", __func__); 1898 exit(0); 1899 case SSHMUX_COMMAND_OPEN: 1900 if (mux_client_request_forwards(sock) != 0) { 1901 error("%s: master forward request failed", __func__); 1902 return; 1903 } 1904 mux_client_request_session(sock); 1905 return; 1906 case SSHMUX_COMMAND_STDIO_FWD: 1907 mux_client_request_stdio_fwd(sock); 1908 exit(0); 1909 default: 1910 fatal("unrecognised muxclient_command %d", muxclient_command); 1911 } 1912 } 1913