mux.c revision 1.4
1 /* $NetBSD: mux.c,v 1.4 2011/07/25 03:03:10 christos Exp $ */ 2 /* $OpenBSD: mux.c,v 1.24 2011/01/13 21:54:53 djm Exp $ */ 3 /* 4 * Copyright (c) 2002-2008 Damien Miller <djm (at) 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 1.4 2011/07/25 03:03:10 christos Exp $"); 36 #include <sys/types.h> 37 #include <sys/param.h> 38 #include <sys/queue.h> 39 #include <sys/stat.h> 40 #include <sys/socket.h> 41 #include <sys/un.h> 42 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <poll.h> 46 #include <signal.h> 47 #include <stdarg.h> 48 #include <stddef.h> 49 #include <stdlib.h> 50 #include <stdio.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <util.h> 54 #include <paths.h> 55 56 #include "atomicio.h" 57 #include "xmalloc.h" 58 #include "log.h" 59 #include "ssh.h" 60 #include "ssh2.h" 61 #include "pathnames.h" 62 #include "misc.h" 63 #include "match.h" 64 #include "buffer.h" 65 #include "channels.h" 66 #include "msg.h" 67 #include "packet.h" 68 #include "monitor_fdpass.h" 69 #include "sshpty.h" 70 #include "key.h" 71 #include "readconf.h" 72 #include "clientloop.h" 73 74 /* from ssh.c */ 75 extern int tty_flag; 76 extern 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 %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 char *orig_control_path = options.control_path; 1015 char rbuf[16+1]; 1016 u_int i, r; 1017 1018 if (options.control_path == NULL || 1019 options.control_master == SSHCTL_MASTER_NO) 1020 return; 1021 1022 debug("setting up multiplex master socket"); 1023 1024 /* 1025 * Use a temporary path before listen so we can pseudo-atomically 1026 * establish the listening socket in its final location to avoid 1027 * other processes racing in between bind() and listen() and hitting 1028 * an unready socket. 1029 */ 1030 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1031 r = arc4random_uniform(26+26+10); 1032 rbuf[i] = (r < 26) ? 'a' + r : 1033 (r < 26*2) ? 'A' + r - 26 : 1034 '0' + r - 26 - 26; 1035 } 1036 rbuf[sizeof(rbuf) - 1] = '\0'; 1037 options.control_path = NULL; 1038 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1039 debug3("%s: temporary control path %s", __func__, options.control_path); 1040 1041 memset(&addr, '\0', sizeof(addr)); 1042 addr.sun_family = AF_UNIX; 1043 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 1044 strlen(options.control_path) + 1; 1045 1046 if (strlcpy(addr.sun_path, options.control_path, 1047 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 1048 fatal("ControlPath too long"); 1049 1050 if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1051 fatal("%s socket(): %s", __func__, strerror(errno)); 1052 1053 old_umask = umask(0177); 1054 if (bind(muxserver_sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 1055 muxserver_sock = -1; 1056 if (errno == EINVAL || errno == EADDRINUSE) { 1057 error("ControlSocket %s already exists, " 1058 "disabling multiplexing", options.control_path); 1059 disable_mux_master: 1060 close(muxserver_sock); 1061 muxserver_sock = -1; 1062 xfree(options.control_path); 1063 options.control_path = NULL; 1064 options.control_master = SSHCTL_MASTER_NO; 1065 return; 1066 } else 1067 fatal("%s bind(): %s", __func__, strerror(errno)); 1068 } 1069 umask(old_umask); 1070 1071 if (listen(muxserver_sock, 64) == -1) 1072 fatal("%s listen(): %s", __func__, strerror(errno)); 1073 1074 /* Now atomically "move" the mux socket into position */ 1075 if (link(options.control_path, orig_control_path) != 0) { 1076 if (errno != EEXIST) { 1077 fatal("%s: link mux listener %s => %s: %s", __func__, 1078 options.control_path, orig_control_path, 1079 strerror(errno)); 1080 } 1081 error("ControlSocket %s already exists, disabling multiplexing", 1082 orig_control_path); 1083 xfree(orig_control_path); 1084 unlink(options.control_path); 1085 goto disable_mux_master; 1086 } 1087 unlink(options.control_path); 1088 xfree(options.control_path); 1089 options.control_path = orig_control_path; 1090 1091 set_nonblock(muxserver_sock); 1092 1093 mux_listener_channel = channel_new("mux listener", 1094 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1095 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1096 0, options.control_path, 1); 1097 mux_listener_channel->mux_rcb = mux_master_read_cb; 1098 debug3("%s: mux listener channel %d fd %d", __func__, 1099 mux_listener_channel->self, mux_listener_channel->sock); 1100 } 1101 1102 /* Callback on open confirmation in mux master for a mux client session. */ 1103 static void 1104 mux_session_confirm(int id, int success, void *arg) 1105 { 1106 struct mux_session_confirm_ctx *cctx = arg; 1107 const char *display; 1108 Channel *c, *cc; 1109 int i; 1110 Buffer reply; 1111 1112 if (cctx == NULL) 1113 fatal("%s: cctx == NULL", __func__); 1114 if ((c = channel_by_id(id)) == NULL) 1115 fatal("%s: no channel for id %d", __func__, id); 1116 if ((cc = channel_by_id(c->ctl_chan)) == NULL) 1117 fatal("%s: channel %d lacks control channel %d", __func__, 1118 id, c->ctl_chan); 1119 1120 if (!success) { 1121 debug3("%s: sending failure reply", __func__); 1122 /* prepare reply */ 1123 buffer_init(&reply); 1124 buffer_put_int(&reply, MUX_S_FAILURE); 1125 buffer_put_int(&reply, cctx->rid); 1126 buffer_put_cstring(&reply, "Session open refused by peer"); 1127 goto done; 1128 } 1129 1130 display = getenv("DISPLAY"); 1131 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1132 char *proto, *data; 1133 1134 /* Get reasonable local authentication information. */ 1135 client_x11_get_proto(display, options.xauth_location, 1136 options.forward_x11_trusted, options.forward_x11_timeout, 1137 &proto, &data); 1138 /* Request forwarding with authentication spoofing. */ 1139 debug("Requesting X11 forwarding with authentication " 1140 "spoofing."); 1141 x11_request_forwarding_with_spoofing(id, display, proto, data); 1142 /* XXX wait for reply */ 1143 } 1144 1145 if (cctx->want_agent_fwd && options.forward_agent) { 1146 debug("Requesting authentication agent forwarding."); 1147 channel_request_start(id, "auth-agent-req (at) openssh.com", 0); 1148 packet_send(); 1149 } 1150 1151 client_session2_setup(id, cctx->want_tty, cctx->want_subsys, 1152 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1153 1154 debug3("%s: sending success reply", __func__); 1155 /* prepare reply */ 1156 buffer_init(&reply); 1157 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1158 buffer_put_int(&reply, cctx->rid); 1159 buffer_put_int(&reply, c->self); 1160 1161 done: 1162 /* Send reply */ 1163 buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1164 buffer_free(&reply); 1165 1166 if (cc->mux_pause <= 0) 1167 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1168 cc->mux_pause = 0; /* start processing messages again */ 1169 c->open_confirm_ctx = NULL; 1170 buffer_free(&cctx->cmd); 1171 xfree(cctx->term); 1172 if (cctx->env != NULL) { 1173 for (i = 0; cctx->env[i] != NULL; i++) 1174 xfree(cctx->env[i]); 1175 xfree(cctx->env); 1176 } 1177 xfree(cctx); 1178 } 1179 1180 /* ** Multiplexing client support */ 1181 1182 /* Exit signal handler */ 1183 static void 1184 control_client_sighandler(int signo) 1185 { 1186 muxclient_terminate = signo; 1187 } 1188 1189 /* 1190 * Relay signal handler - used to pass some signals from mux client to 1191 * mux master. 1192 */ 1193 static void 1194 control_client_sigrelay(int signo) 1195 { 1196 int save_errno = errno; 1197 1198 if (muxserver_pid > 1) 1199 kill(muxserver_pid, signo); 1200 1201 errno = save_errno; 1202 } 1203 1204 static int 1205 mux_client_read(int fd, Buffer *b, u_int need) 1206 { 1207 u_int have; 1208 ssize_t len; 1209 u_char *p; 1210 struct pollfd pfd; 1211 1212 pfd.fd = fd; 1213 pfd.events = POLLIN; 1214 p = buffer_append_space(b, need); 1215 for (have = 0; have < need; ) { 1216 if (muxclient_terminate) { 1217 errno = EINTR; 1218 return -1; 1219 } 1220 len = read(fd, p + have, need - have); 1221 if (len < 0) { 1222 switch (errno) { 1223 case EAGAIN: 1224 (void)poll(&pfd, 1, -1); 1225 /* FALLTHROUGH */ 1226 case EINTR: 1227 continue; 1228 default: 1229 return -1; 1230 } 1231 } 1232 if (len == 0) { 1233 errno = EPIPE; 1234 return -1; 1235 } 1236 have += (u_int)len; 1237 } 1238 return 0; 1239 } 1240 1241 static int 1242 mux_client_write_packet(int fd, Buffer *m) 1243 { 1244 Buffer queue; 1245 u_int have, need; 1246 int oerrno, len; 1247 u_char *ptr; 1248 struct pollfd pfd; 1249 1250 pfd.fd = fd; 1251 pfd.events = POLLOUT; 1252 buffer_init(&queue); 1253 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1254 1255 need = buffer_len(&queue); 1256 ptr = buffer_ptr(&queue); 1257 1258 for (have = 0; have < need; ) { 1259 if (muxclient_terminate) { 1260 buffer_free(&queue); 1261 errno = EINTR; 1262 return -1; 1263 } 1264 len = write(fd, ptr + have, need - have); 1265 if (len < 0) { 1266 switch (errno) { 1267 case EAGAIN: 1268 (void)poll(&pfd, 1, -1); 1269 /* FALLTHROUGH */ 1270 case EINTR: 1271 continue; 1272 default: 1273 oerrno = errno; 1274 buffer_free(&queue); 1275 errno = oerrno; 1276 return -1; 1277 } 1278 } 1279 if (len == 0) { 1280 buffer_free(&queue); 1281 errno = EPIPE; 1282 return -1; 1283 } 1284 have += (u_int)len; 1285 } 1286 buffer_free(&queue); 1287 return 0; 1288 } 1289 1290 static int 1291 mux_client_read_packet(int fd, Buffer *m) 1292 { 1293 Buffer queue; 1294 u_int need, have; 1295 void *ptr; 1296 int oerrno; 1297 1298 buffer_init(&queue); 1299 if (mux_client_read(fd, &queue, 4) != 0) { 1300 if ((oerrno = errno) == EPIPE) 1301 debug3("%s: read header failed: %s", __func__, strerror(errno)); 1302 errno = oerrno; 1303 return -1; 1304 } 1305 need = get_u32(buffer_ptr(&queue)); 1306 if (mux_client_read(fd, &queue, need) != 0) { 1307 oerrno = errno; 1308 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1309 errno = oerrno; 1310 return -1; 1311 } 1312 ptr = buffer_get_string_ptr(&queue, &have); 1313 buffer_append(m, ptr, have); 1314 buffer_free(&queue); 1315 return 0; 1316 } 1317 1318 static int 1319 mux_client_hello_exchange(int fd) 1320 { 1321 Buffer m; 1322 u_int type, ver; 1323 1324 buffer_init(&m); 1325 buffer_put_int(&m, MUX_MSG_HELLO); 1326 buffer_put_int(&m, SSHMUX_VER); 1327 /* no extensions */ 1328 1329 if (mux_client_write_packet(fd, &m) != 0) 1330 fatal("%s: write packet: %s", __func__, strerror(errno)); 1331 1332 buffer_clear(&m); 1333 1334 /* Read their HELLO */ 1335 if (mux_client_read_packet(fd, &m) != 0) { 1336 buffer_free(&m); 1337 return -1; 1338 } 1339 1340 type = buffer_get_int(&m); 1341 if (type != MUX_MSG_HELLO) 1342 fatal("%s: expected HELLO (%u) received %u", 1343 __func__, MUX_MSG_HELLO, type); 1344 ver = buffer_get_int(&m); 1345 if (ver != SSHMUX_VER) 1346 fatal("Unsupported multiplexing protocol version %d " 1347 "(expected %d)", ver, SSHMUX_VER); 1348 debug2("%s: master version %u", __func__, ver); 1349 /* No extensions are presently defined */ 1350 while (buffer_len(&m) > 0) { 1351 char *name = buffer_get_string(&m, NULL); 1352 char *value = buffer_get_string(&m, NULL); 1353 1354 debug2("Unrecognised master extension \"%s\"", name); 1355 xfree(name); 1356 xfree(value); 1357 } 1358 buffer_free(&m); 1359 return 0; 1360 } 1361 1362 static u_int 1363 mux_client_request_alive(int fd) 1364 { 1365 Buffer m; 1366 char *e; 1367 u_int pid, type, rid; 1368 1369 debug3("%s: entering", __func__); 1370 1371 buffer_init(&m); 1372 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1373 buffer_put_int(&m, muxclient_request_id); 1374 1375 if (mux_client_write_packet(fd, &m) != 0) 1376 fatal("%s: write packet: %s", __func__, strerror(errno)); 1377 1378 buffer_clear(&m); 1379 1380 /* Read their reply */ 1381 if (mux_client_read_packet(fd, &m) != 0) { 1382 buffer_free(&m); 1383 return 0; 1384 } 1385 1386 type = buffer_get_int(&m); 1387 if (type != MUX_S_ALIVE) { 1388 e = buffer_get_string(&m, NULL); 1389 fatal("%s: master returned error: %s", __func__, e); 1390 } 1391 1392 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1393 fatal("%s: out of sequence reply: my id %u theirs %u", 1394 __func__, muxclient_request_id, rid); 1395 pid = buffer_get_int(&m); 1396 buffer_free(&m); 1397 1398 debug3("%s: done pid = %u", __func__, pid); 1399 1400 muxclient_request_id++; 1401 1402 return pid; 1403 } 1404 1405 static void 1406 mux_client_request_terminate(int fd) 1407 { 1408 Buffer m; 1409 char *e; 1410 u_int type, rid; 1411 1412 debug3("%s: entering", __func__); 1413 1414 buffer_init(&m); 1415 buffer_put_int(&m, MUX_C_TERMINATE); 1416 buffer_put_int(&m, muxclient_request_id); 1417 1418 if (mux_client_write_packet(fd, &m) != 0) 1419 fatal("%s: write packet: %s", __func__, strerror(errno)); 1420 1421 buffer_clear(&m); 1422 1423 /* Read their reply */ 1424 if (mux_client_read_packet(fd, &m) != 0) { 1425 /* Remote end exited already */ 1426 if (errno == EPIPE) { 1427 buffer_free(&m); 1428 return; 1429 } 1430 fatal("%s: read from master failed: %s", 1431 __func__, strerror(errno)); 1432 } 1433 1434 type = buffer_get_int(&m); 1435 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1436 fatal("%s: out of sequence reply: my id %u theirs %u", 1437 __func__, muxclient_request_id, rid); 1438 switch (type) { 1439 case MUX_S_OK: 1440 break; 1441 case MUX_S_PERMISSION_DENIED: 1442 e = buffer_get_string(&m, NULL); 1443 fatal("Master refused termination request: %s", e); 1444 case MUX_S_FAILURE: 1445 e = buffer_get_string(&m, NULL); 1446 fatal("%s: termination request failed: %s", __func__, e); 1447 default: 1448 fatal("%s: unexpected response from master 0x%08x", 1449 __func__, type); 1450 } 1451 buffer_free(&m); 1452 muxclient_request_id++; 1453 } 1454 1455 static int 1456 mux_client_request_forward(int fd, u_int ftype, Forward *fwd) 1457 { 1458 Buffer m; 1459 char *e, *fwd_desc; 1460 u_int type, rid; 1461 1462 fwd_desc = format_forward(ftype, fwd); 1463 debug("Requesting %s", fwd_desc); 1464 xfree(fwd_desc); 1465 1466 buffer_init(&m); 1467 buffer_put_int(&m, MUX_C_OPEN_FWD); 1468 buffer_put_int(&m, muxclient_request_id); 1469 buffer_put_int(&m, ftype); 1470 buffer_put_cstring(&m, 1471 fwd->listen_host == NULL ? "" : fwd->listen_host); 1472 buffer_put_int(&m, fwd->listen_port); 1473 buffer_put_cstring(&m, 1474 fwd->connect_host == NULL ? "" : fwd->connect_host); 1475 buffer_put_int(&m, fwd->connect_port); 1476 1477 if (mux_client_write_packet(fd, &m) != 0) 1478 fatal("%s: write packet: %s", __func__, strerror(errno)); 1479 1480 buffer_clear(&m); 1481 1482 /* Read their reply */ 1483 if (mux_client_read_packet(fd, &m) != 0) { 1484 buffer_free(&m); 1485 return -1; 1486 } 1487 1488 type = buffer_get_int(&m); 1489 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1490 fatal("%s: out of sequence reply: my id %u theirs %u", 1491 __func__, muxclient_request_id, rid); 1492 switch (type) { 1493 case MUX_S_OK: 1494 break; 1495 case MUX_S_REMOTE_PORT: 1496 fwd->allocated_port = buffer_get_int(&m); 1497 logit("Allocated port %u for remote forward to %s:%d", 1498 fwd->allocated_port, 1499 fwd->connect_host ? fwd->connect_host : "", 1500 fwd->connect_port); 1501 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1502 fprintf(stdout, "%u\n", fwd->allocated_port); 1503 break; 1504 case MUX_S_PERMISSION_DENIED: 1505 e = buffer_get_string(&m, NULL); 1506 buffer_free(&m); 1507 error("Master refused forwarding request: %s", e); 1508 return -1; 1509 case MUX_S_FAILURE: 1510 e = buffer_get_string(&m, NULL); 1511 buffer_free(&m); 1512 error("%s: forwarding request failed: %s", __func__, e); 1513 return -1; 1514 default: 1515 fatal("%s: unexpected response from master 0x%08x", 1516 __func__, type); 1517 } 1518 buffer_free(&m); 1519 1520 muxclient_request_id++; 1521 return 0; 1522 } 1523 1524 static int 1525 mux_client_request_forwards(int fd) 1526 { 1527 int i; 1528 1529 debug3("%s: requesting forwardings: %d local, %d remote", __func__, 1530 options.num_local_forwards, options.num_remote_forwards); 1531 1532 /* XXX ExitOnForwardingFailure */ 1533 for (i = 0; i < options.num_local_forwards; i++) { 1534 if (mux_client_request_forward(fd, 1535 options.local_forwards[i].connect_port == 0 ? 1536 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1537 options.local_forwards + i) != 0) 1538 return -1; 1539 } 1540 for (i = 0; i < options.num_remote_forwards; i++) { 1541 if (mux_client_request_forward(fd, MUX_FWD_REMOTE, 1542 options.remote_forwards + i) != 0) 1543 return -1; 1544 } 1545 return 0; 1546 } 1547 1548 static int 1549 mux_client_request_session(int fd) 1550 { 1551 Buffer m; 1552 char *e, *term; 1553 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1554 extern char **environ; 1555 int devnull; 1556 1557 debug3("%s: entering", __func__); 1558 1559 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1560 error("%s: master alive request failed", __func__); 1561 return -1; 1562 } 1563 1564 signal(SIGPIPE, SIG_IGN); 1565 1566 if (stdin_null_flag) { 1567 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1568 fatal("open(/dev/null): %s", strerror(errno)); 1569 if (dup2(devnull, STDIN_FILENO) == -1) 1570 fatal("dup2: %s", strerror(errno)); 1571 if (devnull > STDERR_FILENO) 1572 close(devnull); 1573 } 1574 1575 term = getenv("TERM"); 1576 1577 buffer_init(&m); 1578 buffer_put_int(&m, MUX_C_NEW_SESSION); 1579 buffer_put_int(&m, muxclient_request_id); 1580 buffer_put_cstring(&m, ""); /* reserved */ 1581 buffer_put_int(&m, tty_flag); 1582 buffer_put_int(&m, options.forward_x11); 1583 buffer_put_int(&m, options.forward_agent); 1584 buffer_put_int(&m, subsystem_flag); 1585 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1586 0xffffffff : (u_int)options.escape_char); 1587 buffer_put_cstring(&m, term == NULL ? "" : term); 1588 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1589 1590 if (options.num_send_env > 0 && environ != NULL) { 1591 /* Pass environment */ 1592 for (i = 0; environ[i] != NULL; i++) { 1593 if (env_permitted(environ[i])) { 1594 buffer_put_cstring(&m, environ[i]); 1595 } 1596 } 1597 } 1598 1599 if (mux_client_write_packet(fd, &m) != 0) 1600 fatal("%s: write packet: %s", __func__, strerror(errno)); 1601 1602 /* Send the stdio file descriptors */ 1603 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1604 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1605 mm_send_fd(fd, STDERR_FILENO) == -1) 1606 fatal("%s: send fds failed", __func__); 1607 1608 debug3("%s: session request sent", __func__); 1609 1610 /* Read their reply */ 1611 buffer_clear(&m); 1612 if (mux_client_read_packet(fd, &m) != 0) { 1613 error("%s: read from master failed: %s", 1614 __func__, strerror(errno)); 1615 buffer_free(&m); 1616 return -1; 1617 } 1618 1619 type = buffer_get_int(&m); 1620 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1621 fatal("%s: out of sequence reply: my id %u theirs %u", 1622 __func__, muxclient_request_id, rid); 1623 switch (type) { 1624 case MUX_S_SESSION_OPENED: 1625 sid = buffer_get_int(&m); 1626 debug("%s: master session id: %u", __func__, sid); 1627 break; 1628 case MUX_S_PERMISSION_DENIED: 1629 e = buffer_get_string(&m, NULL); 1630 buffer_free(&m); 1631 error("Master refused session request: %s", e); 1632 return -1; 1633 case MUX_S_FAILURE: 1634 e = buffer_get_string(&m, NULL); 1635 buffer_free(&m); 1636 error("%s: session request failed: %s", __func__, e); 1637 return -1; 1638 default: 1639 buffer_free(&m); 1640 error("%s: unexpected response from master 0x%08x", 1641 __func__, type); 1642 return -1; 1643 } 1644 muxclient_request_id++; 1645 1646 signal(SIGHUP, control_client_sighandler); 1647 signal(SIGINT, control_client_sighandler); 1648 signal(SIGTERM, control_client_sighandler); 1649 signal(SIGWINCH, control_client_sigrelay); 1650 1651 if (tty_flag) 1652 enter_raw_mode(force_tty_flag); 1653 1654 /* 1655 * Stick around until the controlee closes the client_fd. 1656 * Before it does, it is expected to write an exit message. 1657 * This process must read the value and wait for the closure of 1658 * the client_fd; if this one closes early, the multiplex master will 1659 * terminate early too (possibly losing data). 1660 */ 1661 for (exitval = 255, exitval_seen = 0;;) { 1662 buffer_clear(&m); 1663 if (mux_client_read_packet(fd, &m) != 0) 1664 break; 1665 type = buffer_get_int(&m); 1666 if (type != MUX_S_EXIT_MESSAGE) { 1667 e = buffer_get_string(&m, NULL); 1668 fatal("%s: master returned error: %s", __func__, e); 1669 } 1670 if ((esid = buffer_get_int(&m)) != sid) 1671 fatal("%s: exit on unknown session: my id %u theirs %u", 1672 __func__, sid, esid); 1673 debug("%s: master session id: %u", __func__, sid); 1674 if (exitval_seen) 1675 fatal("%s: exitval sent twice", __func__); 1676 exitval = buffer_get_int(&m); 1677 exitval_seen = 1; 1678 } 1679 1680 close(fd); 1681 leave_raw_mode(force_tty_flag); 1682 1683 if (muxclient_terminate) { 1684 debug2("Exiting on signal %ld", (long)muxclient_terminate); 1685 exitval = 255; 1686 } else if (!exitval_seen) { 1687 debug2("Control master terminated unexpectedly"); 1688 exitval = 255; 1689 } else 1690 debug2("Received exit status from master %d", exitval); 1691 1692 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 1693 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 1694 1695 exit(exitval); 1696 } 1697 1698 static int 1699 mux_client_request_stdio_fwd(int fd) 1700 { 1701 Buffer m; 1702 char *e; 1703 u_int type, rid, sid; 1704 int devnull; 1705 1706 debug3("%s: entering", __func__); 1707 1708 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1709 error("%s: master alive request failed", __func__); 1710 return -1; 1711 } 1712 1713 signal(SIGPIPE, SIG_IGN); 1714 1715 if (stdin_null_flag) { 1716 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1717 fatal("open(/dev/null): %s", strerror(errno)); 1718 if (dup2(devnull, STDIN_FILENO) == -1) 1719 fatal("dup2: %s", strerror(errno)); 1720 if (devnull > STDERR_FILENO) 1721 close(devnull); 1722 } 1723 1724 buffer_init(&m); 1725 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 1726 buffer_put_int(&m, muxclient_request_id); 1727 buffer_put_cstring(&m, ""); /* reserved */ 1728 buffer_put_cstring(&m, stdio_forward_host); 1729 buffer_put_int(&m, stdio_forward_port); 1730 1731 if (mux_client_write_packet(fd, &m) != 0) 1732 fatal("%s: write packet: %s", __func__, strerror(errno)); 1733 1734 /* Send the stdio file descriptors */ 1735 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1736 mm_send_fd(fd, STDOUT_FILENO) == -1) 1737 fatal("%s: send fds failed", __func__); 1738 1739 debug3("%s: stdio forward request sent", __func__); 1740 1741 /* Read their reply */ 1742 buffer_clear(&m); 1743 1744 if (mux_client_read_packet(fd, &m) != 0) { 1745 error("%s: read from master failed: %s", 1746 __func__, strerror(errno)); 1747 buffer_free(&m); 1748 return -1; 1749 } 1750 1751 type = buffer_get_int(&m); 1752 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1753 fatal("%s: out of sequence reply: my id %u theirs %u", 1754 __func__, muxclient_request_id, rid); 1755 switch (type) { 1756 case MUX_S_SESSION_OPENED: 1757 sid = buffer_get_int(&m); 1758 debug("%s: master session id: %u", __func__, sid); 1759 break; 1760 case MUX_S_PERMISSION_DENIED: 1761 e = buffer_get_string(&m, NULL); 1762 buffer_free(&m); 1763 fatal("Master refused stdio forwarding request: %s", e); 1764 case MUX_S_FAILURE: 1765 e = buffer_get_string(&m, NULL); 1766 buffer_free(&m); 1767 fatal("%s: stdio forwarding request failed: %s", __func__, e); 1768 default: 1769 buffer_free(&m); 1770 error("%s: unexpected response from master 0x%08x", 1771 __func__, type); 1772 return -1; 1773 } 1774 muxclient_request_id++; 1775 1776 signal(SIGHUP, control_client_sighandler); 1777 signal(SIGINT, control_client_sighandler); 1778 signal(SIGTERM, control_client_sighandler); 1779 signal(SIGWINCH, control_client_sigrelay); 1780 1781 /* 1782 * Stick around until the controlee closes the client_fd. 1783 */ 1784 buffer_clear(&m); 1785 if (mux_client_read_packet(fd, &m) != 0) { 1786 if (errno == EPIPE || 1787 (errno == EINTR && muxclient_terminate != 0)) 1788 return 0; 1789 fatal("%s: mux_client_read_packet: %s", 1790 __func__, strerror(errno)); 1791 } 1792 fatal("%s: master returned unexpected message %u", __func__, type); 1793 } 1794 1795 /* Multiplex client main loop. */ 1796 void 1797 muxclient(const char *path) 1798 { 1799 struct sockaddr_un addr; 1800 int sock; 1801 u_int pid; 1802 1803 if (muxclient_command == 0) { 1804 if (stdio_forward_host != NULL) 1805 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 1806 else 1807 muxclient_command = SSHMUX_COMMAND_OPEN; 1808 } 1809 1810 switch (options.control_master) { 1811 case SSHCTL_MASTER_AUTO: 1812 case SSHCTL_MASTER_AUTO_ASK: 1813 debug("auto-mux: Trying existing master"); 1814 /* FALLTHROUGH */ 1815 case SSHCTL_MASTER_NO: 1816 break; 1817 default: 1818 return; 1819 } 1820 1821 memset(&addr, '\0', sizeof(addr)); 1822 addr.sun_family = AF_UNIX; 1823 addr.sun_len = offsetof(struct sockaddr_un, sun_path) + 1824 strlen(path) + 1; 1825 1826 if (strlcpy(addr.sun_path, path, 1827 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 1828 fatal("ControlPath too long"); 1829 1830 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 1831 fatal("%s socket(): %s", __func__, strerror(errno)); 1832 1833 if (connect(sock, (struct sockaddr *)&addr, addr.sun_len) == -1) { 1834 switch (muxclient_command) { 1835 case SSHMUX_COMMAND_OPEN: 1836 case SSHMUX_COMMAND_STDIO_FWD: 1837 break; 1838 default: 1839 fatal("Control socket connect(%.100s): %s", path, 1840 strerror(errno)); 1841 } 1842 if (errno == ECONNREFUSED && 1843 options.control_master != SSHCTL_MASTER_NO) { 1844 debug("Stale control socket %.100s, unlinking", path); 1845 unlink(path); 1846 } else if (errno == ENOENT) { 1847 debug("Control socket \"%.100s\" does not exist", path); 1848 } else { 1849 error("Control socket connect(%.100s): %s", path, 1850 strerror(errno)); 1851 } 1852 close(sock); 1853 return; 1854 } 1855 set_nonblock(sock); 1856 1857 if (mux_client_hello_exchange(sock) != 0) { 1858 error("%s: master hello exchange failed", __func__); 1859 close(sock); 1860 return; 1861 } 1862 1863 switch (muxclient_command) { 1864 case SSHMUX_COMMAND_ALIVE_CHECK: 1865 if ((pid = mux_client_request_alive(sock)) == 0) 1866 fatal("%s: master alive check failed", __func__); 1867 fprintf(stderr, "Master running (pid=%d)\r\n", pid); 1868 exit(0); 1869 case SSHMUX_COMMAND_TERMINATE: 1870 mux_client_request_terminate(sock); 1871 fprintf(stderr, "Exit request sent.\r\n"); 1872 exit(0); 1873 case SSHMUX_COMMAND_FORWARD: 1874 if (mux_client_request_forwards(sock) != 0) 1875 fatal("%s: master forward request failed", __func__); 1876 exit(0); 1877 case SSHMUX_COMMAND_OPEN: 1878 if (mux_client_request_forwards(sock) != 0) { 1879 error("%s: master forward request failed", __func__); 1880 return; 1881 } 1882 mux_client_request_session(sock); 1883 return; 1884 case SSHMUX_COMMAND_STDIO_FWD: 1885 mux_client_request_stdio_fwd(sock); 1886 exit(0); 1887 default: 1888 fatal("unrecognised muxclient_command %d", muxclient_command); 1889 } 1890 } 1891
Indexes created Mon Apr 27 00:23:16 UTC 2026