1 /* $OpenBSD: mux.c,v 1.69 2017/09/20 05:19:00 dtucker 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/stat.h> 37 #include <sys/socket.h> 38 #include <sys/un.h> 39 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <signal.h> 43 #include <stdarg.h> 44 #include <stddef.h> 45 #include <stdlib.h> 46 #include <stdio.h> 47 #include <string.h> 48 #include <unistd.h> 49 #ifdef HAVE_PATHS_H 50 #include <paths.h> 51 #endif 52 53 #ifdef HAVE_POLL_H 54 #include <poll.h> 55 #else 56 # ifdef HAVE_SYS_POLL_H 57 # include <sys/poll.h> 58 # endif 59 #endif 60 61 #ifdef HAVE_UTIL_H 62 # include <util.h> 63 #endif 64 65 #include "openbsd-compat/sys-queue.h" 66 #include "xmalloc.h" 67 #include "log.h" 68 #include "ssh.h" 69 #include "ssh2.h" 70 #include "pathnames.h" 71 #include "misc.h" 72 #include "match.h" 73 #include "buffer.h" 74 #include "channels.h" 75 #include "msg.h" 76 #include "packet.h" 77 #include "monitor_fdpass.h" 78 #include "sshpty.h" 79 #include "key.h" 80 #include "readconf.h" 81 #include "clientloop.h" 82 #include "ssherr.h" 83 84 /* from ssh.c */ 85 extern int tty_flag; 86 extern Options options; 87 extern int stdin_null_flag; 88 extern char *host; 89 extern int subsystem_flag; 90 extern Buffer command; 91 extern volatile sig_atomic_t quit_pending; 92 93 /* Context for session open confirmation callback */ 94 struct mux_session_confirm_ctx { 95 u_int want_tty; 96 u_int want_subsys; 97 u_int want_x_fwd; 98 u_int want_agent_fwd; 99 Buffer cmd; 100 char *term; 101 struct termios tio; 102 char **env; 103 u_int rid; 104 }; 105 106 /* Context for stdio fwd open confirmation callback */ 107 struct mux_stdio_confirm_ctx { 108 u_int rid; 109 }; 110 111 /* Context for global channel callback */ 112 struct mux_channel_confirm_ctx { 113 u_int cid; /* channel id */ 114 u_int rid; /* request id */ 115 int fid; /* forward id */ 116 }; 117 118 /* fd to control socket */ 119 int muxserver_sock = -1; 120 121 /* client request id */ 122 u_int muxclient_request_id = 0; 123 124 /* Multiplexing control command */ 125 u_int muxclient_command = 0; 126 127 /* Set when signalled. */ 128 static volatile sig_atomic_t muxclient_terminate = 0; 129 130 /* PID of multiplex server */ 131 static u_int muxserver_pid = 0; 132 133 static Channel *mux_listener_channel = NULL; 134 135 struct mux_master_state { 136 int hello_rcvd; 137 }; 138 139 /* mux protocol messages */ 140 #define MUX_MSG_HELLO 0x00000001 141 #define MUX_C_NEW_SESSION 0x10000002 142 #define MUX_C_ALIVE_CHECK 0x10000004 143 #define MUX_C_TERMINATE 0x10000005 144 #define MUX_C_OPEN_FWD 0x10000006 145 #define MUX_C_CLOSE_FWD 0x10000007 146 #define MUX_C_NEW_STDIO_FWD 0x10000008 147 #define MUX_C_STOP_LISTENING 0x10000009 148 #define MUX_C_PROXY 0x1000000f 149 #define MUX_S_OK 0x80000001 150 #define MUX_S_PERMISSION_DENIED 0x80000002 151 #define MUX_S_FAILURE 0x80000003 152 #define MUX_S_EXIT_MESSAGE 0x80000004 153 #define MUX_S_ALIVE 0x80000005 154 #define MUX_S_SESSION_OPENED 0x80000006 155 #define MUX_S_REMOTE_PORT 0x80000007 156 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 157 #define MUX_S_PROXY 0x8000000f 158 159 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 160 #define MUX_FWD_LOCAL 1 161 #define MUX_FWD_REMOTE 2 162 #define MUX_FWD_DYNAMIC 3 163 164 static void mux_session_confirm(struct ssh *, int, int, void *); 165 static void mux_stdio_confirm(struct ssh *, int, int, void *); 166 167 static int process_mux_master_hello(struct ssh *, u_int, 168 Channel *, struct sshbuf *, struct sshbuf *); 169 static int process_mux_new_session(struct ssh *, u_int, 170 Channel *, struct sshbuf *, struct sshbuf *); 171 static int process_mux_alive_check(struct ssh *, u_int, 172 Channel *, struct sshbuf *, struct sshbuf *); 173 static int process_mux_terminate(struct ssh *, u_int, 174 Channel *, struct sshbuf *, struct sshbuf *); 175 static int process_mux_open_fwd(struct ssh *, u_int, 176 Channel *, struct sshbuf *, struct sshbuf *); 177 static int process_mux_close_fwd(struct ssh *, u_int, 178 Channel *, struct sshbuf *, struct sshbuf *); 179 static int process_mux_stdio_fwd(struct ssh *, u_int, 180 Channel *, struct sshbuf *, struct sshbuf *); 181 static int process_mux_stop_listening(struct ssh *, u_int, 182 Channel *, struct sshbuf *, struct sshbuf *); 183 static int process_mux_proxy(struct ssh *, u_int, 184 Channel *, struct sshbuf *, struct sshbuf *); 185 186 static const struct { 187 u_int type; 188 int (*handler)(struct ssh *, u_int, Channel *, 189 struct sshbuf *, struct sshbuf *); 190 } mux_master_handlers[] = { 191 { MUX_MSG_HELLO, process_mux_master_hello }, 192 { MUX_C_NEW_SESSION, process_mux_new_session }, 193 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 194 { MUX_C_TERMINATE, process_mux_terminate }, 195 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 196 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 197 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 198 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 199 { MUX_C_PROXY, process_mux_proxy }, 200 { 0, NULL } 201 }; 202 203 /* Cleanup callback fired on closure of mux slave _session_ channel */ 204 /* ARGSUSED */ 205 static void 206 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused) 207 { 208 Channel *cc, *c = channel_by_id(ssh, cid); 209 210 debug3("%s: entering for channel %d", __func__, cid); 211 if (c == NULL) 212 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 213 if (c->ctl_chan != -1) { 214 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 215 fatal("%s: channel %d missing control channel %d", 216 __func__, c->self, c->ctl_chan); 217 c->ctl_chan = -1; 218 cc->remote_id = 0; 219 cc->have_remote_id = 0; 220 chan_rcvd_oclose(ssh, cc); 221 } 222 channel_cancel_cleanup(ssh, c->self); 223 } 224 225 /* Cleanup callback fired on closure of mux slave _control_ channel */ 226 /* ARGSUSED */ 227 static void 228 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused) 229 { 230 Channel *sc, *c = channel_by_id(ssh, cid); 231 232 debug3("%s: entering for channel %d", __func__, cid); 233 if (c == NULL) 234 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 235 if (c->have_remote_id) { 236 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 237 fatal("%s: channel %d missing session channel %u", 238 __func__, c->self, c->remote_id); 239 c->remote_id = 0; 240 c->have_remote_id = 0; 241 sc->ctl_chan = -1; 242 if (sc->type != SSH_CHANNEL_OPEN && 243 sc->type != SSH_CHANNEL_OPENING) { 244 debug2("%s: channel %d: not open", __func__, sc->self); 245 chan_mark_dead(ssh, sc); 246 } else { 247 if (sc->istate == CHAN_INPUT_OPEN) 248 chan_read_failed(ssh, sc); 249 if (sc->ostate == CHAN_OUTPUT_OPEN) 250 chan_write_failed(ssh, sc); 251 } 252 } 253 channel_cancel_cleanup(ssh, c->self); 254 } 255 256 /* Check mux client environment variables before passing them to mux master. */ 257 static int 258 env_permitted(char *env) 259 { 260 int i, ret; 261 char name[1024], *cp; 262 263 if ((cp = strchr(env, '=')) == NULL || cp == env) 264 return 0; 265 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 266 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 267 error("env_permitted: name '%.100s...' too long", env); 268 return 0; 269 } 270 271 for (i = 0; i < options.num_send_env; i++) 272 if (match_pattern(name, options.send_env[i])) 273 return 1; 274 275 return 0; 276 } 277 278 /* Mux master protocol message handlers */ 279 280 static int 281 process_mux_master_hello(struct ssh *ssh, u_int rid, 282 Channel *c, Buffer *m, Buffer *r) 283 { 284 u_int ver; 285 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 286 287 if (state == NULL) 288 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 289 if (state->hello_rcvd) { 290 error("%s: HELLO received twice", __func__); 291 return -1; 292 } 293 if (buffer_get_int_ret(&ver, m) != 0) { 294 malf: 295 error("%s: malformed message", __func__); 296 return -1; 297 } 298 if (ver != SSHMUX_VER) { 299 error("Unsupported multiplexing protocol version %d " 300 "(expected %d)", ver, SSHMUX_VER); 301 return -1; 302 } 303 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 304 305 /* No extensions are presently defined */ 306 while (buffer_len(m) > 0) { 307 char *name = buffer_get_string_ret(m, NULL); 308 char *value = buffer_get_string_ret(m, NULL); 309 310 if (name == NULL || value == NULL) { 311 free(name); 312 free(value); 313 goto malf; 314 } 315 debug2("Unrecognised slave extension \"%s\"", name); 316 free(name); 317 free(value); 318 } 319 state->hello_rcvd = 1; 320 return 0; 321 } 322 323 static int 324 process_mux_new_session(struct ssh *ssh, u_int rid, 325 Channel *c, Buffer *m, Buffer *r) 326 { 327 Channel *nc; 328 struct mux_session_confirm_ctx *cctx; 329 char *reserved, *cmd, *cp; 330 u_int i, j, len, env_len, escape_char, window, packetmax; 331 int new_fd[3]; 332 333 /* Reply for SSHMUX_COMMAND_OPEN */ 334 cctx = xcalloc(1, sizeof(*cctx)); 335 cctx->term = NULL; 336 cctx->rid = rid; 337 cmd = reserved = NULL; 338 cctx->env = NULL; 339 env_len = 0; 340 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 341 buffer_get_int_ret(&cctx->want_tty, m) != 0 || 342 buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || 343 buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || 344 buffer_get_int_ret(&cctx->want_subsys, m) != 0 || 345 buffer_get_int_ret(&escape_char, m) != 0 || 346 (cctx->term = buffer_get_string_ret(m, &len)) == NULL || 347 (cmd = buffer_get_string_ret(m, &len)) == NULL) { 348 malf: 349 free(cmd); 350 free(reserved); 351 for (j = 0; j < env_len; j++) 352 free(cctx->env[j]); 353 free(cctx->env); 354 free(cctx->term); 355 free(cctx); 356 error("%s: malformed message", __func__); 357 return -1; 358 } 359 free(reserved); 360 reserved = NULL; 361 362 while (buffer_len(m) > 0) { 363 #define MUX_MAX_ENV_VARS 4096 364 if ((cp = buffer_get_string_ret(m, &len)) == NULL) 365 goto malf; 366 if (!env_permitted(cp)) { 367 free(cp); 368 continue; 369 } 370 cctx->env = xreallocarray(cctx->env, env_len + 2, 371 sizeof(*cctx->env)); 372 cctx->env[env_len++] = cp; 373 cctx->env[env_len] = NULL; 374 if (env_len > MUX_MAX_ENV_VARS) { 375 error(">%d environment variables received, ignoring " 376 "additional", MUX_MAX_ENV_VARS); 377 break; 378 } 379 } 380 381 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 382 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 383 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 384 cctx->want_subsys, cctx->term, cmd, env_len); 385 386 buffer_init(&cctx->cmd); 387 buffer_append(&cctx->cmd, cmd, strlen(cmd)); 388 free(cmd); 389 cmd = NULL; 390 391 /* Gather fds from client */ 392 for(i = 0; i < 3; i++) { 393 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 394 error("%s: failed to receive fd %d from slave", 395 __func__, i); 396 for (j = 0; j < i; j++) 397 close(new_fd[j]); 398 for (j = 0; j < env_len; j++) 399 free(cctx->env[j]); 400 free(cctx->env); 401 free(cctx->term); 402 buffer_free(&cctx->cmd); 403 free(cctx); 404 405 /* prepare reply */ 406 buffer_put_int(r, MUX_S_FAILURE); 407 buffer_put_int(r, rid); 408 buffer_put_cstring(r, 409 "did not receive file descriptors"); 410 return -1; 411 } 412 } 413 414 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 415 new_fd[0], new_fd[1], new_fd[2]); 416 417 /* XXX support multiple child sessions in future */ 418 if (c->have_remote_id) { 419 debug2("%s: session already open", __func__); 420 /* prepare reply */ 421 buffer_put_int(r, MUX_S_FAILURE); 422 buffer_put_int(r, rid); 423 buffer_put_cstring(r, "Multiple sessions not supported"); 424 cleanup: 425 close(new_fd[0]); 426 close(new_fd[1]); 427 close(new_fd[2]); 428 free(cctx->term); 429 if (env_len != 0) { 430 for (i = 0; i < env_len; i++) 431 free(cctx->env[i]); 432 free(cctx->env); 433 } 434 buffer_free(&cctx->cmd); 435 free(cctx); 436 return 0; 437 } 438 439 if (options.control_master == SSHCTL_MASTER_ASK || 440 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 441 if (!ask_permission("Allow shared connection to %s? ", host)) { 442 debug2("%s: session refused by user", __func__); 443 /* prepare reply */ 444 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 445 buffer_put_int(r, rid); 446 buffer_put_cstring(r, "Permission denied"); 447 goto cleanup; 448 } 449 } 450 451 /* Try to pick up ttymodes from client before it goes raw */ 452 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 453 error("%s: tcgetattr: %s", __func__, strerror(errno)); 454 455 /* enable nonblocking unless tty */ 456 if (!isatty(new_fd[0])) 457 set_nonblock(new_fd[0]); 458 if (!isatty(new_fd[1])) 459 set_nonblock(new_fd[1]); 460 if (!isatty(new_fd[2])) 461 set_nonblock(new_fd[2]); 462 463 window = CHAN_SES_WINDOW_DEFAULT; 464 packetmax = CHAN_SES_PACKET_DEFAULT; 465 if (cctx->want_tty) { 466 window >>= 1; 467 packetmax >>= 1; 468 } 469 470 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 471 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 472 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 473 474 nc->ctl_chan = c->self; /* link session -> control channel */ 475 c->remote_id = nc->self; /* link control -> session channel */ 476 c->have_remote_id = 1; 477 478 if (cctx->want_tty && escape_char != 0xffffffff) { 479 channel_register_filter(ssh, nc->self, 480 client_simple_escape_filter, NULL, 481 client_filter_cleanup, 482 client_new_escape_filter_ctx((int)escape_char)); 483 } 484 485 debug2("%s: channel_new: %d linked to control channel %d", 486 __func__, nc->self, nc->ctl_chan); 487 488 channel_send_open(ssh, nc->self); 489 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 490 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 491 channel_register_cleanup(ssh, nc->self, 492 mux_master_session_cleanup_cb, 1); 493 494 /* reply is deferred, sent by mux_session_confirm */ 495 return 0; 496 } 497 498 static int 499 process_mux_alive_check(struct ssh *ssh, u_int rid, 500 Channel *c, Buffer *m, Buffer *r) 501 { 502 debug2("%s: channel %d: alive check", __func__, c->self); 503 504 /* prepare reply */ 505 buffer_put_int(r, MUX_S_ALIVE); 506 buffer_put_int(r, rid); 507 buffer_put_int(r, (u_int)getpid()); 508 509 return 0; 510 } 511 512 static int 513 process_mux_terminate(struct ssh *ssh, u_int rid, 514 Channel *c, Buffer *m, Buffer *r) 515 { 516 debug2("%s: channel %d: terminate request", __func__, c->self); 517 518 if (options.control_master == SSHCTL_MASTER_ASK || 519 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 520 if (!ask_permission("Terminate shared connection to %s? ", 521 host)) { 522 debug2("%s: termination refused by user", __func__); 523 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 524 buffer_put_int(r, rid); 525 buffer_put_cstring(r, "Permission denied"); 526 return 0; 527 } 528 } 529 530 quit_pending = 1; 531 buffer_put_int(r, MUX_S_OK); 532 buffer_put_int(r, rid); 533 /* XXX exit happens too soon - message never makes it to client */ 534 return 0; 535 } 536 537 static char * 538 format_forward(u_int ftype, struct Forward *fwd) 539 { 540 char *ret; 541 542 switch (ftype) { 543 case MUX_FWD_LOCAL: 544 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 545 (fwd->listen_path != NULL) ? fwd->listen_path : 546 (fwd->listen_host == NULL) ? 547 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 548 fwd->listen_host, fwd->listen_port, 549 (fwd->connect_path != NULL) ? fwd->connect_path : 550 fwd->connect_host, fwd->connect_port); 551 break; 552 case MUX_FWD_DYNAMIC: 553 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 554 (fwd->listen_host == NULL) ? 555 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 556 fwd->listen_host, fwd->listen_port); 557 break; 558 case MUX_FWD_REMOTE: 559 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 560 (fwd->listen_path != NULL) ? fwd->listen_path : 561 (fwd->listen_host == NULL) ? 562 "LOCALHOST" : fwd->listen_host, 563 fwd->listen_port, 564 (fwd->connect_path != NULL) ? fwd->connect_path : 565 fwd->connect_host, fwd->connect_port); 566 break; 567 default: 568 fatal("%s: unknown forward type %u", __func__, ftype); 569 } 570 return ret; 571 } 572 573 static int 574 compare_host(const char *a, const char *b) 575 { 576 if (a == NULL && b == NULL) 577 return 1; 578 if (a == NULL || b == NULL) 579 return 0; 580 return strcmp(a, b) == 0; 581 } 582 583 static int 584 compare_forward(struct Forward *a, struct Forward *b) 585 { 586 if (!compare_host(a->listen_host, b->listen_host)) 587 return 0; 588 if (!compare_host(a->listen_path, b->listen_path)) 589 return 0; 590 if (a->listen_port != b->listen_port) 591 return 0; 592 if (!compare_host(a->connect_host, b->connect_host)) 593 return 0; 594 if (!compare_host(a->connect_path, b->connect_path)) 595 return 0; 596 if (a->connect_port != b->connect_port) 597 return 0; 598 599 return 1; 600 } 601 602 static void 603 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 604 { 605 struct mux_channel_confirm_ctx *fctx = ctxt; 606 char *failmsg = NULL; 607 struct Forward *rfwd; 608 Channel *c; 609 Buffer out; 610 611 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 612 /* no channel for reply */ 613 error("%s: unknown channel", __func__); 614 return; 615 } 616 buffer_init(&out); 617 if (fctx->fid >= options.num_remote_forwards || 618 (options.remote_forwards[fctx->fid].connect_path == NULL && 619 options.remote_forwards[fctx->fid].connect_host == NULL)) { 620 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 621 goto fail; 622 } 623 rfwd = &options.remote_forwards[fctx->fid]; 624 debug("%s: %s for: listen %d, connect %s:%d", __func__, 625 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 626 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 627 rfwd->connect_host, rfwd->connect_port); 628 if (type == SSH2_MSG_REQUEST_SUCCESS) { 629 if (rfwd->listen_port == 0) { 630 rfwd->allocated_port = packet_get_int(); 631 debug("Allocated port %u for mux remote forward" 632 " to %s:%d", rfwd->allocated_port, 633 rfwd->connect_host, rfwd->connect_port); 634 buffer_put_int(&out, MUX_S_REMOTE_PORT); 635 buffer_put_int(&out, fctx->rid); 636 buffer_put_int(&out, rfwd->allocated_port); 637 channel_update_permitted_opens(ssh, rfwd->handle, 638 rfwd->allocated_port); 639 } else { 640 buffer_put_int(&out, MUX_S_OK); 641 buffer_put_int(&out, fctx->rid); 642 } 643 goto out; 644 } else { 645 if (rfwd->listen_port == 0) 646 channel_update_permitted_opens(ssh, rfwd->handle, -1); 647 if (rfwd->listen_path != NULL) 648 xasprintf(&failmsg, "remote port forwarding failed for " 649 "listen path %s", rfwd->listen_path); 650 else 651 xasprintf(&failmsg, "remote port forwarding failed for " 652 "listen port %d", rfwd->listen_port); 653 654 debug2("%s: clearing registered forwarding for listen %d, " 655 "connect %s:%d", __func__, rfwd->listen_port, 656 rfwd->connect_path ? rfwd->connect_path : 657 rfwd->connect_host, rfwd->connect_port); 658 659 free(rfwd->listen_host); 660 free(rfwd->listen_path); 661 free(rfwd->connect_host); 662 free(rfwd->connect_path); 663 memset(rfwd, 0, sizeof(*rfwd)); 664 } 665 fail: 666 error("%s: %s", __func__, failmsg); 667 buffer_put_int(&out, MUX_S_FAILURE); 668 buffer_put_int(&out, fctx->rid); 669 buffer_put_cstring(&out, failmsg); 670 free(failmsg); 671 out: 672 buffer_put_string(c->output, buffer_ptr(&out), buffer_len(&out)); 673 buffer_free(&out); 674 if (c->mux_pause <= 0) 675 fatal("%s: mux_pause %d", __func__, c->mux_pause); 676 c->mux_pause = 0; /* start processing messages again */ 677 } 678 679 static int 680 process_mux_open_fwd(struct ssh *ssh, u_int rid, 681 Channel *c, Buffer *m, Buffer *r) 682 { 683 struct Forward fwd; 684 char *fwd_desc = NULL; 685 char *listen_addr, *connect_addr; 686 u_int ftype; 687 u_int lport, cport; 688 int i, ret = 0, freefwd = 1; 689 690 memset(&fwd, 0, sizeof(fwd)); 691 692 /* XXX - lport/cport check redundant */ 693 if (buffer_get_int_ret(&ftype, m) != 0 || 694 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 695 buffer_get_int_ret(&lport, m) != 0 || 696 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 697 buffer_get_int_ret(&cport, m) != 0 || 698 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 699 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 700 error("%s: malformed message", __func__); 701 ret = -1; 702 goto out; 703 } 704 if (*listen_addr == '\0') { 705 free(listen_addr); 706 listen_addr = NULL; 707 } 708 if (*connect_addr == '\0') { 709 free(connect_addr); 710 connect_addr = NULL; 711 } 712 713 memset(&fwd, 0, sizeof(fwd)); 714 fwd.listen_port = lport; 715 if (fwd.listen_port == PORT_STREAMLOCAL) 716 fwd.listen_path = listen_addr; 717 else 718 fwd.listen_host = listen_addr; 719 fwd.connect_port = cport; 720 if (fwd.connect_port == PORT_STREAMLOCAL) 721 fwd.connect_path = connect_addr; 722 else 723 fwd.connect_host = connect_addr; 724 725 debug2("%s: channel %d: request %s", __func__, c->self, 726 (fwd_desc = format_forward(ftype, &fwd))); 727 728 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 729 ftype != MUX_FWD_DYNAMIC) { 730 logit("%s: invalid forwarding type %u", __func__, ftype); 731 invalid: 732 free(listen_addr); 733 free(connect_addr); 734 buffer_put_int(r, MUX_S_FAILURE); 735 buffer_put_int(r, rid); 736 buffer_put_cstring(r, "Invalid forwarding request"); 737 return 0; 738 } 739 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 740 logit("%s: streamlocal and dynamic forwards " 741 "are mutually exclusive", __func__); 742 goto invalid; 743 } 744 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 745 logit("%s: invalid listen port %u", __func__, 746 fwd.listen_port); 747 goto invalid; 748 } 749 if ((fwd.connect_port != PORT_STREAMLOCAL && 750 fwd.connect_port >= 65536) || 751 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 752 fwd.connect_port == 0)) { 753 logit("%s: invalid connect port %u", __func__, 754 fwd.connect_port); 755 goto invalid; 756 } 757 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 758 fwd.connect_path == NULL) { 759 logit("%s: missing connect host", __func__); 760 goto invalid; 761 } 762 763 /* Skip forwards that have already been requested */ 764 switch (ftype) { 765 case MUX_FWD_LOCAL: 766 case MUX_FWD_DYNAMIC: 767 for (i = 0; i < options.num_local_forwards; i++) { 768 if (compare_forward(&fwd, 769 options.local_forwards + i)) { 770 exists: 771 debug2("%s: found existing forwarding", 772 __func__); 773 buffer_put_int(r, MUX_S_OK); 774 buffer_put_int(r, rid); 775 goto out; 776 } 777 } 778 break; 779 case MUX_FWD_REMOTE: 780 for (i = 0; i < options.num_remote_forwards; i++) { 781 if (compare_forward(&fwd, 782 options.remote_forwards + i)) { 783 if (fwd.listen_port != 0) 784 goto exists; 785 debug2("%s: found allocated port", 786 __func__); 787 buffer_put_int(r, MUX_S_REMOTE_PORT); 788 buffer_put_int(r, rid); 789 buffer_put_int(r, 790 options.remote_forwards[i].allocated_port); 791 goto out; 792 } 793 } 794 break; 795 } 796 797 if (options.control_master == SSHCTL_MASTER_ASK || 798 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 799 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 800 debug2("%s: forwarding refused by user", __func__); 801 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 802 buffer_put_int(r, rid); 803 buffer_put_cstring(r, "Permission denied"); 804 goto out; 805 } 806 } 807 808 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 809 if (!channel_setup_local_fwd_listener(ssh, &fwd, 810 &options.fwd_opts)) { 811 fail: 812 logit("slave-requested %s failed", fwd_desc); 813 buffer_put_int(r, MUX_S_FAILURE); 814 buffer_put_int(r, rid); 815 buffer_put_cstring(r, "Port forwarding failed"); 816 goto out; 817 } 818 add_local_forward(&options, &fwd); 819 freefwd = 0; 820 } else { 821 struct mux_channel_confirm_ctx *fctx; 822 823 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 824 if (fwd.handle < 0) 825 goto fail; 826 add_remote_forward(&options, &fwd); 827 fctx = xcalloc(1, sizeof(*fctx)); 828 fctx->cid = c->self; 829 fctx->rid = rid; 830 fctx->fid = options.num_remote_forwards - 1; 831 client_register_global_confirm(mux_confirm_remote_forward, 832 fctx); 833 freefwd = 0; 834 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 835 /* delayed reply in mux_confirm_remote_forward */ 836 goto out; 837 } 838 buffer_put_int(r, MUX_S_OK); 839 buffer_put_int(r, rid); 840 out: 841 free(fwd_desc); 842 if (freefwd) { 843 free(fwd.listen_host); 844 free(fwd.listen_path); 845 free(fwd.connect_host); 846 free(fwd.connect_path); 847 } 848 return ret; 849 } 850 851 static int 852 process_mux_close_fwd(struct ssh *ssh, u_int rid, 853 Channel *c, Buffer *m, Buffer *r) 854 { 855 struct Forward fwd, *found_fwd; 856 char *fwd_desc = NULL; 857 const char *error_reason = NULL; 858 char *listen_addr = NULL, *connect_addr = NULL; 859 u_int ftype; 860 int i, ret = 0; 861 u_int lport, cport; 862 863 memset(&fwd, 0, sizeof(fwd)); 864 865 if (buffer_get_int_ret(&ftype, m) != 0 || 866 (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || 867 buffer_get_int_ret(&lport, m) != 0 || 868 (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || 869 buffer_get_int_ret(&cport, m) != 0 || 870 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 871 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 872 error("%s: malformed message", __func__); 873 ret = -1; 874 goto out; 875 } 876 877 if (*listen_addr == '\0') { 878 free(listen_addr); 879 listen_addr = NULL; 880 } 881 if (*connect_addr == '\0') { 882 free(connect_addr); 883 connect_addr = NULL; 884 } 885 886 memset(&fwd, 0, sizeof(fwd)); 887 fwd.listen_port = lport; 888 if (fwd.listen_port == PORT_STREAMLOCAL) 889 fwd.listen_path = listen_addr; 890 else 891 fwd.listen_host = listen_addr; 892 fwd.connect_port = cport; 893 if (fwd.connect_port == PORT_STREAMLOCAL) 894 fwd.connect_path = connect_addr; 895 else 896 fwd.connect_host = connect_addr; 897 898 debug2("%s: channel %d: request cancel %s", __func__, c->self, 899 (fwd_desc = format_forward(ftype, &fwd))); 900 901 /* make sure this has been requested */ 902 found_fwd = NULL; 903 switch (ftype) { 904 case MUX_FWD_LOCAL: 905 case MUX_FWD_DYNAMIC: 906 for (i = 0; i < options.num_local_forwards; i++) { 907 if (compare_forward(&fwd, 908 options.local_forwards + i)) { 909 found_fwd = options.local_forwards + i; 910 break; 911 } 912 } 913 break; 914 case MUX_FWD_REMOTE: 915 for (i = 0; i < options.num_remote_forwards; i++) { 916 if (compare_forward(&fwd, 917 options.remote_forwards + i)) { 918 found_fwd = options.remote_forwards + i; 919 break; 920 } 921 } 922 break; 923 } 924 925 if (found_fwd == NULL) 926 error_reason = "port not forwarded"; 927 else if (ftype == MUX_FWD_REMOTE) { 928 /* 929 * This shouldn't fail unless we confused the host/port 930 * between options.remote_forwards and permitted_opens. 931 * However, for dynamic allocated listen ports we need 932 * to use the actual listen port. 933 */ 934 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 935 error_reason = "port not in permitted opens"; 936 } else { /* local and dynamic forwards */ 937 /* Ditto */ 938 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 939 &options.fwd_opts) == -1) 940 error_reason = "port not found"; 941 } 942 943 if (error_reason == NULL) { 944 buffer_put_int(r, MUX_S_OK); 945 buffer_put_int(r, rid); 946 947 free(found_fwd->listen_host); 948 free(found_fwd->listen_path); 949 free(found_fwd->connect_host); 950 free(found_fwd->connect_path); 951 found_fwd->listen_host = found_fwd->connect_host = NULL; 952 found_fwd->listen_path = found_fwd->connect_path = NULL; 953 found_fwd->listen_port = found_fwd->connect_port = 0; 954 } else { 955 buffer_put_int(r, MUX_S_FAILURE); 956 buffer_put_int(r, rid); 957 buffer_put_cstring(r, error_reason); 958 } 959 out: 960 free(fwd_desc); 961 free(listen_addr); 962 free(connect_addr); 963 964 return ret; 965 } 966 967 static int 968 process_mux_stdio_fwd(struct ssh *ssh, u_int rid, 969 Channel *c, Buffer *m, Buffer *r) 970 { 971 Channel *nc; 972 char *reserved, *chost; 973 u_int cport, i, j; 974 int new_fd[2]; 975 struct mux_stdio_confirm_ctx *cctx; 976 977 chost = reserved = NULL; 978 if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || 979 (chost = buffer_get_string_ret(m, NULL)) == NULL || 980 buffer_get_int_ret(&cport, m) != 0) { 981 free(reserved); 982 free(chost); 983 error("%s: malformed message", __func__); 984 return -1; 985 } 986 free(reserved); 987 988 debug2("%s: channel %d: request stdio fwd to %s:%u", 989 __func__, c->self, chost, cport); 990 991 /* Gather fds from client */ 992 for(i = 0; i < 2; i++) { 993 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 994 error("%s: failed to receive fd %d from slave", 995 __func__, i); 996 for (j = 0; j < i; j++) 997 close(new_fd[j]); 998 free(chost); 999 1000 /* prepare reply */ 1001 buffer_put_int(r, MUX_S_FAILURE); 1002 buffer_put_int(r, rid); 1003 buffer_put_cstring(r, 1004 "did not receive file descriptors"); 1005 return -1; 1006 } 1007 } 1008 1009 debug3("%s: got fds stdin %d, stdout %d", __func__, 1010 new_fd[0], new_fd[1]); 1011 1012 /* XXX support multiple child sessions in future */ 1013 if (c->have_remote_id) { 1014 debug2("%s: session already open", __func__); 1015 /* prepare reply */ 1016 buffer_put_int(r, MUX_S_FAILURE); 1017 buffer_put_int(r, rid); 1018 buffer_put_cstring(r, "Multiple sessions not supported"); 1019 cleanup: 1020 close(new_fd[0]); 1021 close(new_fd[1]); 1022 free(chost); 1023 return 0; 1024 } 1025 1026 if (options.control_master == SSHCTL_MASTER_ASK || 1027 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1028 if (!ask_permission("Allow forward to %s:%u? ", 1029 chost, cport)) { 1030 debug2("%s: stdio fwd refused by user", __func__); 1031 /* prepare reply */ 1032 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1033 buffer_put_int(r, rid); 1034 buffer_put_cstring(r, "Permission denied"); 1035 goto cleanup; 1036 } 1037 } 1038 1039 /* enable nonblocking unless tty */ 1040 if (!isatty(new_fd[0])) 1041 set_nonblock(new_fd[0]); 1042 if (!isatty(new_fd[1])) 1043 set_nonblock(new_fd[1]); 1044 1045 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]); 1046 1047 nc->ctl_chan = c->self; /* link session -> control channel */ 1048 c->remote_id = nc->self; /* link control -> session channel */ 1049 c->have_remote_id = 1; 1050 1051 debug2("%s: channel_new: %d linked to control channel %d", 1052 __func__, nc->self, nc->ctl_chan); 1053 1054 channel_register_cleanup(ssh, nc->self, 1055 mux_master_session_cleanup_cb, 1); 1056 1057 cctx = xcalloc(1, sizeof(*cctx)); 1058 cctx->rid = rid; 1059 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1060 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1061 1062 /* reply is deferred, sent by mux_session_confirm */ 1063 return 0; 1064 } 1065 1066 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1067 static void 1068 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1069 { 1070 struct mux_stdio_confirm_ctx *cctx = arg; 1071 Channel *c, *cc; 1072 Buffer reply; 1073 1074 if (cctx == NULL) 1075 fatal("%s: cctx == NULL", __func__); 1076 if ((c = channel_by_id(ssh, id)) == NULL) 1077 fatal("%s: no channel for id %d", __func__, id); 1078 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1079 fatal("%s: channel %d lacks control channel %d", __func__, 1080 id, c->ctl_chan); 1081 1082 if (!success) { 1083 debug3("%s: sending failure reply", __func__); 1084 /* prepare reply */ 1085 buffer_init(&reply); 1086 buffer_put_int(&reply, MUX_S_FAILURE); 1087 buffer_put_int(&reply, cctx->rid); 1088 buffer_put_cstring(&reply, "Session open refused by peer"); 1089 goto done; 1090 } 1091 1092 debug3("%s: sending success reply", __func__); 1093 /* prepare reply */ 1094 buffer_init(&reply); 1095 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1096 buffer_put_int(&reply, cctx->rid); 1097 buffer_put_int(&reply, c->self); 1098 1099 done: 1100 /* Send reply */ 1101 buffer_put_string(cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1102 buffer_free(&reply); 1103 1104 if (cc->mux_pause <= 0) 1105 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1106 cc->mux_pause = 0; /* start processing messages again */ 1107 c->open_confirm_ctx = NULL; 1108 free(cctx); 1109 } 1110 1111 static int 1112 process_mux_stop_listening(struct ssh *ssh, u_int rid, 1113 Channel *c, Buffer *m, Buffer *r) 1114 { 1115 debug("%s: channel %d: stop listening", __func__, c->self); 1116 1117 if (options.control_master == SSHCTL_MASTER_ASK || 1118 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1119 if (!ask_permission("Disable further multiplexing on shared " 1120 "connection to %s? ", host)) { 1121 debug2("%s: stop listen refused by user", __func__); 1122 buffer_put_int(r, MUX_S_PERMISSION_DENIED); 1123 buffer_put_int(r, rid); 1124 buffer_put_cstring(r, "Permission denied"); 1125 return 0; 1126 } 1127 } 1128 1129 if (mux_listener_channel != NULL) { 1130 channel_free(ssh, mux_listener_channel); 1131 client_stop_mux(); 1132 free(options.control_path); 1133 options.control_path = NULL; 1134 mux_listener_channel = NULL; 1135 muxserver_sock = -1; 1136 } 1137 1138 /* prepare reply */ 1139 buffer_put_int(r, MUX_S_OK); 1140 buffer_put_int(r, rid); 1141 1142 return 0; 1143 } 1144 1145 static int 1146 process_mux_proxy(struct ssh *ssh, u_int rid, 1147 Channel *c, Buffer *m, Buffer *r) 1148 { 1149 debug("%s: channel %d: proxy request", __func__, c->self); 1150 1151 c->mux_rcb = channel_proxy_downstream; 1152 buffer_put_int(r, MUX_S_PROXY); 1153 buffer_put_int(r, rid); 1154 1155 return 0; 1156 } 1157 1158 /* Channel callbacks fired on read/write from mux slave fd */ 1159 static int 1160 mux_master_read_cb(struct ssh *ssh, Channel *c) 1161 { 1162 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1163 Buffer in, out; 1164 const u_char *ptr; 1165 u_int type, rid, have, i; 1166 int ret = -1; 1167 1168 /* Setup ctx and */ 1169 if (c->mux_ctx == NULL) { 1170 state = xcalloc(1, sizeof(*state)); 1171 c->mux_ctx = state; 1172 channel_register_cleanup(ssh, c->self, 1173 mux_master_control_cleanup_cb, 0); 1174 1175 /* Send hello */ 1176 buffer_init(&out); 1177 buffer_put_int(&out, MUX_MSG_HELLO); 1178 buffer_put_int(&out, SSHMUX_VER); 1179 /* no extensions */ 1180 buffer_put_string(c->output, buffer_ptr(&out), 1181 buffer_len(&out)); 1182 buffer_free(&out); 1183 debug3("%s: channel %d: hello sent", __func__, c->self); 1184 return 0; 1185 } 1186 1187 buffer_init(&in); 1188 buffer_init(&out); 1189 1190 /* Channel code ensures that we receive whole packets */ 1191 if ((ptr = buffer_get_string_ptr_ret(c->input, &have)) == NULL) { 1192 malf: 1193 error("%s: malformed message", __func__); 1194 goto out; 1195 } 1196 buffer_append(&in, ptr, have); 1197 1198 if (buffer_get_int_ret(&type, &in) != 0) 1199 goto malf; 1200 debug3("%s: channel %d packet type 0x%08x len %u", 1201 __func__, c->self, type, buffer_len(&in)); 1202 1203 if (type == MUX_MSG_HELLO) 1204 rid = 0; 1205 else { 1206 if (!state->hello_rcvd) { 1207 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1208 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1209 goto out; 1210 } 1211 if (buffer_get_int_ret(&rid, &in) != 0) 1212 goto malf; 1213 } 1214 1215 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1216 if (type == mux_master_handlers[i].type) { 1217 ret = mux_master_handlers[i].handler(ssh, rid, 1218 c, &in, &out); 1219 break; 1220 } 1221 } 1222 if (mux_master_handlers[i].handler == NULL) { 1223 error("%s: unsupported mux message 0x%08x", __func__, type); 1224 buffer_put_int(&out, MUX_S_FAILURE); 1225 buffer_put_int(&out, rid); 1226 buffer_put_cstring(&out, "unsupported request"); 1227 ret = 0; 1228 } 1229 /* Enqueue reply packet */ 1230 if (buffer_len(&out) != 0) { 1231 buffer_put_string(c->output, buffer_ptr(&out), 1232 buffer_len(&out)); 1233 } 1234 out: 1235 buffer_free(&in); 1236 buffer_free(&out); 1237 return ret; 1238 } 1239 1240 void 1241 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1242 { 1243 Buffer m; 1244 Channel *mux_chan; 1245 1246 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1247 exitval); 1248 1249 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1250 fatal("%s: channel %d missing mux channel %d", 1251 __func__, c->self, c->ctl_chan); 1252 1253 /* Append exit message packet to control socket output queue */ 1254 buffer_init(&m); 1255 buffer_put_int(&m, MUX_S_EXIT_MESSAGE); 1256 buffer_put_int(&m, c->self); 1257 buffer_put_int(&m, exitval); 1258 1259 buffer_put_string(mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1260 buffer_free(&m); 1261 } 1262 1263 void 1264 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1265 { 1266 Buffer m; 1267 Channel *mux_chan; 1268 1269 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1270 1271 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1272 fatal("%s: channel %d missing mux channel %d", 1273 __func__, c->self, c->ctl_chan); 1274 1275 /* Append exit message packet to control socket output queue */ 1276 buffer_init(&m); 1277 buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); 1278 buffer_put_int(&m, c->self); 1279 1280 buffer_put_string(mux_chan->output, buffer_ptr(&m), buffer_len(&m)); 1281 buffer_free(&m); 1282 } 1283 1284 /* Prepare a mux master to listen on a Unix domain socket. */ 1285 void 1286 muxserver_listen(struct ssh *ssh) 1287 { 1288 mode_t old_umask; 1289 char *orig_control_path = options.control_path; 1290 char rbuf[16+1]; 1291 u_int i, r; 1292 int oerrno; 1293 1294 if (options.control_path == NULL || 1295 options.control_master == SSHCTL_MASTER_NO) 1296 return; 1297 1298 debug("setting up multiplex master socket"); 1299 1300 /* 1301 * Use a temporary path before listen so we can pseudo-atomically 1302 * establish the listening socket in its final location to avoid 1303 * other processes racing in between bind() and listen() and hitting 1304 * an unready socket. 1305 */ 1306 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1307 r = arc4random_uniform(26+26+10); 1308 rbuf[i] = (r < 26) ? 'a' + r : 1309 (r < 26*2) ? 'A' + r - 26 : 1310 '0' + r - 26 - 26; 1311 } 1312 rbuf[sizeof(rbuf) - 1] = '\0'; 1313 options.control_path = NULL; 1314 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1315 debug3("%s: temporary control path %s", __func__, options.control_path); 1316 1317 old_umask = umask(0177); 1318 muxserver_sock = unix_listener(options.control_path, 64, 0); 1319 oerrno = errno; 1320 umask(old_umask); 1321 if (muxserver_sock < 0) { 1322 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1323 error("ControlSocket %s already exists, " 1324 "disabling multiplexing", options.control_path); 1325 disable_mux_master: 1326 if (muxserver_sock != -1) { 1327 close(muxserver_sock); 1328 muxserver_sock = -1; 1329 } 1330 free(orig_control_path); 1331 free(options.control_path); 1332 options.control_path = NULL; 1333 options.control_master = SSHCTL_MASTER_NO; 1334 return; 1335 } else { 1336 /* unix_listener() logs the error */ 1337 cleanup_exit(255); 1338 } 1339 } 1340 1341 /* Now atomically "move" the mux socket into position */ 1342 if (link(options.control_path, orig_control_path) != 0) { 1343 if (errno != EEXIST) { 1344 fatal("%s: link mux listener %s => %s: %s", __func__, 1345 options.control_path, orig_control_path, 1346 strerror(errno)); 1347 } 1348 error("ControlSocket %s already exists, disabling multiplexing", 1349 orig_control_path); 1350 unlink(options.control_path); 1351 goto disable_mux_master; 1352 } 1353 unlink(options.control_path); 1354 free(options.control_path); 1355 options.control_path = orig_control_path; 1356 1357 set_nonblock(muxserver_sock); 1358 1359 mux_listener_channel = channel_new(ssh, "mux listener", 1360 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1361 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1362 0, options.control_path, 1); 1363 mux_listener_channel->mux_rcb = mux_master_read_cb; 1364 debug3("%s: mux listener channel %d fd %d", __func__, 1365 mux_listener_channel->self, mux_listener_channel->sock); 1366 } 1367 1368 /* Callback on open confirmation in mux master for a mux client session. */ 1369 static void 1370 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1371 { 1372 struct mux_session_confirm_ctx *cctx = arg; 1373 const char *display; 1374 Channel *c, *cc; 1375 int i; 1376 Buffer reply; 1377 1378 if (cctx == NULL) 1379 fatal("%s: cctx == NULL", __func__); 1380 if ((c = channel_by_id(ssh, id)) == NULL) 1381 fatal("%s: no channel for id %d", __func__, id); 1382 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1383 fatal("%s: channel %d lacks control channel %d", __func__, 1384 id, c->ctl_chan); 1385 1386 if (!success) { 1387 debug3("%s: sending failure reply", __func__); 1388 /* prepare reply */ 1389 buffer_init(&reply); 1390 buffer_put_int(&reply, MUX_S_FAILURE); 1391 buffer_put_int(&reply, cctx->rid); 1392 buffer_put_cstring(&reply, "Session open refused by peer"); 1393 goto done; 1394 } 1395 1396 display = getenv("DISPLAY"); 1397 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1398 char *proto, *data; 1399 1400 /* Get reasonable local authentication information. */ 1401 if (client_x11_get_proto(ssh, display, options.xauth_location, 1402 options.forward_x11_trusted, options.forward_x11_timeout, 1403 &proto, &data) == 0) { 1404 /* Request forwarding with authentication spoofing. */ 1405 debug("Requesting X11 forwarding with authentication " 1406 "spoofing."); 1407 x11_request_forwarding_with_spoofing(ssh, id, 1408 display, proto, data, 1); 1409 /* XXX exit_on_forward_failure */ 1410 client_expect_confirm(ssh, id, "X11 forwarding", 1411 CONFIRM_WARN); 1412 } 1413 } 1414 1415 if (cctx->want_agent_fwd && options.forward_agent) { 1416 debug("Requesting authentication agent forwarding."); 1417 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1418 packet_send(); 1419 } 1420 1421 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1422 cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); 1423 1424 debug3("%s: sending success reply", __func__); 1425 /* prepare reply */ 1426 buffer_init(&reply); 1427 buffer_put_int(&reply, MUX_S_SESSION_OPENED); 1428 buffer_put_int(&reply, cctx->rid); 1429 buffer_put_int(&reply, c->self); 1430 1431 done: 1432 /* Send reply */ 1433 buffer_put_string(cc->output, buffer_ptr(&reply), buffer_len(&reply)); 1434 buffer_free(&reply); 1435 1436 if (cc->mux_pause <= 0) 1437 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1438 cc->mux_pause = 0; /* start processing messages again */ 1439 c->open_confirm_ctx = NULL; 1440 buffer_free(&cctx->cmd); 1441 free(cctx->term); 1442 if (cctx->env != NULL) { 1443 for (i = 0; cctx->env[i] != NULL; i++) 1444 free(cctx->env[i]); 1445 free(cctx->env); 1446 } 1447 free(cctx); 1448 } 1449 1450 /* ** Multiplexing client support */ 1451 1452 /* Exit signal handler */ 1453 static void 1454 control_client_sighandler(int signo) 1455 { 1456 muxclient_terminate = signo; 1457 } 1458 1459 /* 1460 * Relay signal handler - used to pass some signals from mux client to 1461 * mux master. 1462 */ 1463 static void 1464 control_client_sigrelay(int signo) 1465 { 1466 int save_errno = errno; 1467 1468 if (muxserver_pid > 1) 1469 kill(muxserver_pid, signo); 1470 1471 errno = save_errno; 1472 } 1473 1474 static int 1475 mux_client_read(int fd, Buffer *b, u_int need) 1476 { 1477 u_int have; 1478 ssize_t len; 1479 u_char *p; 1480 struct pollfd pfd; 1481 1482 pfd.fd = fd; 1483 pfd.events = POLLIN; 1484 p = buffer_append_space(b, need); 1485 for (have = 0; have < need; ) { 1486 if (muxclient_terminate) { 1487 errno = EINTR; 1488 return -1; 1489 } 1490 len = read(fd, p + have, need - have); 1491 if (len < 0) { 1492 switch (errno) { 1493 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1494 case EWOULDBLOCK: 1495 #endif 1496 case EAGAIN: 1497 (void)poll(&pfd, 1, -1); 1498 /* FALLTHROUGH */ 1499 case EINTR: 1500 continue; 1501 default: 1502 return -1; 1503 } 1504 } 1505 if (len == 0) { 1506 errno = EPIPE; 1507 return -1; 1508 } 1509 have += (u_int)len; 1510 } 1511 return 0; 1512 } 1513 1514 static int 1515 mux_client_write_packet(int fd, Buffer *m) 1516 { 1517 Buffer queue; 1518 u_int have, need; 1519 int oerrno, len; 1520 u_char *ptr; 1521 struct pollfd pfd; 1522 1523 pfd.fd = fd; 1524 pfd.events = POLLOUT; 1525 buffer_init(&queue); 1526 buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); 1527 1528 need = buffer_len(&queue); 1529 ptr = buffer_ptr(&queue); 1530 1531 for (have = 0; have < need; ) { 1532 if (muxclient_terminate) { 1533 buffer_free(&queue); 1534 errno = EINTR; 1535 return -1; 1536 } 1537 len = write(fd, ptr + have, need - have); 1538 if (len < 0) { 1539 switch (errno) { 1540 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1541 case EWOULDBLOCK: 1542 #endif 1543 case EAGAIN: 1544 (void)poll(&pfd, 1, -1); 1545 /* FALLTHROUGH */ 1546 case EINTR: 1547 continue; 1548 default: 1549 oerrno = errno; 1550 buffer_free(&queue); 1551 errno = oerrno; 1552 return -1; 1553 } 1554 } 1555 if (len == 0) { 1556 buffer_free(&queue); 1557 errno = EPIPE; 1558 return -1; 1559 } 1560 have += (u_int)len; 1561 } 1562 buffer_free(&queue); 1563 return 0; 1564 } 1565 1566 static int 1567 mux_client_read_packet(int fd, Buffer *m) 1568 { 1569 Buffer queue; 1570 u_int need, have; 1571 const u_char *ptr; 1572 int oerrno; 1573 1574 buffer_init(&queue); 1575 if (mux_client_read(fd, &queue, 4) != 0) { 1576 if ((oerrno = errno) == EPIPE) 1577 debug3("%s: read header failed: %s", __func__, 1578 strerror(errno)); 1579 buffer_free(&queue); 1580 errno = oerrno; 1581 return -1; 1582 } 1583 need = get_u32(buffer_ptr(&queue)); 1584 if (mux_client_read(fd, &queue, need) != 0) { 1585 oerrno = errno; 1586 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1587 buffer_free(&queue); 1588 errno = oerrno; 1589 return -1; 1590 } 1591 ptr = buffer_get_string_ptr(&queue, &have); 1592 buffer_append(m, ptr, have); 1593 buffer_free(&queue); 1594 return 0; 1595 } 1596 1597 static int 1598 mux_client_hello_exchange(int fd) 1599 { 1600 Buffer m; 1601 u_int type, ver; 1602 int ret = -1; 1603 1604 buffer_init(&m); 1605 buffer_put_int(&m, MUX_MSG_HELLO); 1606 buffer_put_int(&m, SSHMUX_VER); 1607 /* no extensions */ 1608 1609 if (mux_client_write_packet(fd, &m) != 0) { 1610 debug("%s: write packet: %s", __func__, strerror(errno)); 1611 goto out; 1612 } 1613 1614 buffer_clear(&m); 1615 1616 /* Read their HELLO */ 1617 if (mux_client_read_packet(fd, &m) != 0) { 1618 debug("%s: read packet failed", __func__); 1619 goto out; 1620 } 1621 1622 type = buffer_get_int(&m); 1623 if (type != MUX_MSG_HELLO) { 1624 error("%s: expected HELLO (%u) received %u", 1625 __func__, MUX_MSG_HELLO, type); 1626 goto out; 1627 } 1628 ver = buffer_get_int(&m); 1629 if (ver != SSHMUX_VER) { 1630 error("Unsupported multiplexing protocol version %d " 1631 "(expected %d)", ver, SSHMUX_VER); 1632 goto out; 1633 } 1634 debug2("%s: master version %u", __func__, ver); 1635 /* No extensions are presently defined */ 1636 while (buffer_len(&m) > 0) { 1637 char *name = buffer_get_string(&m, NULL); 1638 char *value = buffer_get_string(&m, NULL); 1639 1640 debug2("Unrecognised master extension \"%s\"", name); 1641 free(name); 1642 free(value); 1643 } 1644 /* success */ 1645 ret = 0; 1646 out: 1647 buffer_free(&m); 1648 return ret; 1649 } 1650 1651 static u_int 1652 mux_client_request_alive(int fd) 1653 { 1654 Buffer m; 1655 char *e; 1656 u_int pid, type, rid; 1657 1658 debug3("%s: entering", __func__); 1659 1660 buffer_init(&m); 1661 buffer_put_int(&m, MUX_C_ALIVE_CHECK); 1662 buffer_put_int(&m, muxclient_request_id); 1663 1664 if (mux_client_write_packet(fd, &m) != 0) 1665 fatal("%s: write packet: %s", __func__, strerror(errno)); 1666 1667 buffer_clear(&m); 1668 1669 /* Read their reply */ 1670 if (mux_client_read_packet(fd, &m) != 0) { 1671 buffer_free(&m); 1672 return 0; 1673 } 1674 1675 type = buffer_get_int(&m); 1676 if (type != MUX_S_ALIVE) { 1677 e = buffer_get_string(&m, NULL); 1678 fatal("%s: master returned error: %s", __func__, e); 1679 } 1680 1681 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1682 fatal("%s: out of sequence reply: my id %u theirs %u", 1683 __func__, muxclient_request_id, rid); 1684 pid = buffer_get_int(&m); 1685 buffer_free(&m); 1686 1687 debug3("%s: done pid = %u", __func__, pid); 1688 1689 muxclient_request_id++; 1690 1691 return pid; 1692 } 1693 1694 static void 1695 mux_client_request_terminate(int fd) 1696 { 1697 Buffer m; 1698 char *e; 1699 u_int type, rid; 1700 1701 debug3("%s: entering", __func__); 1702 1703 buffer_init(&m); 1704 buffer_put_int(&m, MUX_C_TERMINATE); 1705 buffer_put_int(&m, muxclient_request_id); 1706 1707 if (mux_client_write_packet(fd, &m) != 0) 1708 fatal("%s: write packet: %s", __func__, strerror(errno)); 1709 1710 buffer_clear(&m); 1711 1712 /* Read their reply */ 1713 if (mux_client_read_packet(fd, &m) != 0) { 1714 /* Remote end exited already */ 1715 if (errno == EPIPE) { 1716 buffer_free(&m); 1717 return; 1718 } 1719 fatal("%s: read from master failed: %s", 1720 __func__, strerror(errno)); 1721 } 1722 1723 type = buffer_get_int(&m); 1724 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1725 fatal("%s: out of sequence reply: my id %u theirs %u", 1726 __func__, muxclient_request_id, rid); 1727 switch (type) { 1728 case MUX_S_OK: 1729 break; 1730 case MUX_S_PERMISSION_DENIED: 1731 e = buffer_get_string(&m, NULL); 1732 fatal("Master refused termination request: %s", e); 1733 case MUX_S_FAILURE: 1734 e = buffer_get_string(&m, NULL); 1735 fatal("%s: termination request failed: %s", __func__, e); 1736 default: 1737 fatal("%s: unexpected response from master 0x%08x", 1738 __func__, type); 1739 } 1740 buffer_free(&m); 1741 muxclient_request_id++; 1742 } 1743 1744 static int 1745 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1746 { 1747 Buffer m; 1748 char *e, *fwd_desc; 1749 u_int type, rid; 1750 1751 fwd_desc = format_forward(ftype, fwd); 1752 debug("Requesting %s %s", 1753 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1754 free(fwd_desc); 1755 1756 buffer_init(&m); 1757 buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); 1758 buffer_put_int(&m, muxclient_request_id); 1759 buffer_put_int(&m, ftype); 1760 if (fwd->listen_path != NULL) { 1761 buffer_put_cstring(&m, fwd->listen_path); 1762 } else { 1763 buffer_put_cstring(&m, 1764 fwd->listen_host == NULL ? "" : 1765 (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); 1766 } 1767 buffer_put_int(&m, fwd->listen_port); 1768 if (fwd->connect_path != NULL) { 1769 buffer_put_cstring(&m, fwd->connect_path); 1770 } else { 1771 buffer_put_cstring(&m, 1772 fwd->connect_host == NULL ? "" : fwd->connect_host); 1773 } 1774 buffer_put_int(&m, fwd->connect_port); 1775 1776 if (mux_client_write_packet(fd, &m) != 0) 1777 fatal("%s: write packet: %s", __func__, strerror(errno)); 1778 1779 buffer_clear(&m); 1780 1781 /* Read their reply */ 1782 if (mux_client_read_packet(fd, &m) != 0) { 1783 buffer_free(&m); 1784 return -1; 1785 } 1786 1787 type = buffer_get_int(&m); 1788 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1789 fatal("%s: out of sequence reply: my id %u theirs %u", 1790 __func__, muxclient_request_id, rid); 1791 switch (type) { 1792 case MUX_S_OK: 1793 break; 1794 case MUX_S_REMOTE_PORT: 1795 if (cancel_flag) 1796 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1797 fwd->allocated_port = buffer_get_int(&m); 1798 verbose("Allocated port %u for remote forward to %s:%d", 1799 fwd->allocated_port, 1800 fwd->connect_host ? fwd->connect_host : "", 1801 fwd->connect_port); 1802 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1803 fprintf(stdout, "%i\n", fwd->allocated_port); 1804 break; 1805 case MUX_S_PERMISSION_DENIED: 1806 e = buffer_get_string(&m, NULL); 1807 buffer_free(&m); 1808 error("Master refused forwarding request: %s", e); 1809 return -1; 1810 case MUX_S_FAILURE: 1811 e = buffer_get_string(&m, NULL); 1812 buffer_free(&m); 1813 error("%s: forwarding request failed: %s", __func__, e); 1814 return -1; 1815 default: 1816 fatal("%s: unexpected response from master 0x%08x", 1817 __func__, type); 1818 } 1819 buffer_free(&m); 1820 1821 muxclient_request_id++; 1822 return 0; 1823 } 1824 1825 static int 1826 mux_client_forwards(int fd, int cancel_flag) 1827 { 1828 int i, ret = 0; 1829 1830 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1831 cancel_flag ? "cancel" : "request", 1832 options.num_local_forwards, options.num_remote_forwards); 1833 1834 /* XXX ExitOnForwardingFailure */ 1835 for (i = 0; i < options.num_local_forwards; i++) { 1836 if (mux_client_forward(fd, cancel_flag, 1837 options.local_forwards[i].connect_port == 0 ? 1838 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1839 options.local_forwards + i) != 0) 1840 ret = -1; 1841 } 1842 for (i = 0; i < options.num_remote_forwards; i++) { 1843 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1844 options.remote_forwards + i) != 0) 1845 ret = -1; 1846 } 1847 return ret; 1848 } 1849 1850 static int 1851 mux_client_request_session(int fd) 1852 { 1853 Buffer m; 1854 char *e, *term; 1855 u_int i, rid, sid, esid, exitval, type, exitval_seen; 1856 extern char **environ; 1857 int devnull, rawmode; 1858 1859 debug3("%s: entering", __func__); 1860 1861 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1862 error("%s: master alive request failed", __func__); 1863 return -1; 1864 } 1865 1866 signal(SIGPIPE, SIG_IGN); 1867 1868 if (stdin_null_flag) { 1869 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1870 fatal("open(/dev/null): %s", strerror(errno)); 1871 if (dup2(devnull, STDIN_FILENO) == -1) 1872 fatal("dup2: %s", strerror(errno)); 1873 if (devnull > STDERR_FILENO) 1874 close(devnull); 1875 } 1876 1877 term = getenv("TERM"); 1878 1879 buffer_init(&m); 1880 buffer_put_int(&m, MUX_C_NEW_SESSION); 1881 buffer_put_int(&m, muxclient_request_id); 1882 buffer_put_cstring(&m, ""); /* reserved */ 1883 buffer_put_int(&m, tty_flag); 1884 buffer_put_int(&m, options.forward_x11); 1885 buffer_put_int(&m, options.forward_agent); 1886 buffer_put_int(&m, subsystem_flag); 1887 buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 1888 0xffffffff : (u_int)options.escape_char); 1889 buffer_put_cstring(&m, term == NULL ? "" : term); 1890 buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); 1891 1892 if (options.num_send_env > 0 && environ != NULL) { 1893 /* Pass environment */ 1894 for (i = 0; environ[i] != NULL; i++) { 1895 if (env_permitted(environ[i])) { 1896 buffer_put_cstring(&m, environ[i]); 1897 } 1898 } 1899 } 1900 1901 if (mux_client_write_packet(fd, &m) != 0) 1902 fatal("%s: write packet: %s", __func__, strerror(errno)); 1903 1904 /* Send the stdio file descriptors */ 1905 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1906 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1907 mm_send_fd(fd, STDERR_FILENO) == -1) 1908 fatal("%s: send fds failed", __func__); 1909 1910 debug3("%s: session request sent", __func__); 1911 1912 /* Read their reply */ 1913 buffer_clear(&m); 1914 if (mux_client_read_packet(fd, &m) != 0) { 1915 error("%s: read from master failed: %s", 1916 __func__, strerror(errno)); 1917 buffer_free(&m); 1918 return -1; 1919 } 1920 1921 type = buffer_get_int(&m); 1922 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 1923 fatal("%s: out of sequence reply: my id %u theirs %u", 1924 __func__, muxclient_request_id, rid); 1925 switch (type) { 1926 case MUX_S_SESSION_OPENED: 1927 sid = buffer_get_int(&m); 1928 debug("%s: master session id: %u", __func__, sid); 1929 break; 1930 case MUX_S_PERMISSION_DENIED: 1931 e = buffer_get_string(&m, NULL); 1932 buffer_free(&m); 1933 error("Master refused session request: %s", e); 1934 return -1; 1935 case MUX_S_FAILURE: 1936 e = buffer_get_string(&m, NULL); 1937 buffer_free(&m); 1938 error("%s: session request failed: %s", __func__, e); 1939 return -1; 1940 default: 1941 buffer_free(&m); 1942 error("%s: unexpected response from master 0x%08x", 1943 __func__, type); 1944 return -1; 1945 } 1946 muxclient_request_id++; 1947 1948 if (pledge("stdio proc tty", NULL) == -1) 1949 fatal("%s pledge(): %s", __func__, strerror(errno)); 1950 platform_pledge_mux(); 1951 1952 signal(SIGHUP, control_client_sighandler); 1953 signal(SIGINT, control_client_sighandler); 1954 signal(SIGTERM, control_client_sighandler); 1955 signal(SIGWINCH, control_client_sigrelay); 1956 1957 rawmode = tty_flag; 1958 if (tty_flag) 1959 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1960 1961 /* 1962 * Stick around until the controlee closes the client_fd. 1963 * Before it does, it is expected to write an exit message. 1964 * This process must read the value and wait for the closure of 1965 * the client_fd; if this one closes early, the multiplex master will 1966 * terminate early too (possibly losing data). 1967 */ 1968 for (exitval = 255, exitval_seen = 0;;) { 1969 buffer_clear(&m); 1970 if (mux_client_read_packet(fd, &m) != 0) 1971 break; 1972 type = buffer_get_int(&m); 1973 switch (type) { 1974 case MUX_S_TTY_ALLOC_FAIL: 1975 if ((esid = buffer_get_int(&m)) != sid) 1976 fatal("%s: tty alloc fail on unknown session: " 1977 "my id %u theirs %u", 1978 __func__, sid, esid); 1979 leave_raw_mode(options.request_tty == 1980 REQUEST_TTY_FORCE); 1981 rawmode = 0; 1982 continue; 1983 case MUX_S_EXIT_MESSAGE: 1984 if ((esid = buffer_get_int(&m)) != sid) 1985 fatal("%s: exit on unknown session: " 1986 "my id %u theirs %u", 1987 __func__, sid, esid); 1988 if (exitval_seen) 1989 fatal("%s: exitval sent twice", __func__); 1990 exitval = buffer_get_int(&m); 1991 exitval_seen = 1; 1992 continue; 1993 default: 1994 e = buffer_get_string(&m, NULL); 1995 fatal("%s: master returned error: %s", __func__, e); 1996 } 1997 } 1998 1999 close(fd); 2000 if (rawmode) 2001 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2002 2003 if (muxclient_terminate) { 2004 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2005 exitval = 255; 2006 } else if (!exitval_seen) { 2007 debug2("Control master terminated unexpectedly"); 2008 exitval = 255; 2009 } else 2010 debug2("Received exit status from master %d", exitval); 2011 2012 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 2013 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2014 2015 exit(exitval); 2016 } 2017 2018 static int 2019 mux_client_proxy(int fd) 2020 { 2021 Buffer m; 2022 char *e; 2023 u_int type, rid; 2024 2025 buffer_init(&m); 2026 buffer_put_int(&m, MUX_C_PROXY); 2027 buffer_put_int(&m, muxclient_request_id); 2028 if (mux_client_write_packet(fd, &m) != 0) 2029 fatal("%s: write packet: %s", __func__, strerror(errno)); 2030 2031 buffer_clear(&m); 2032 2033 /* Read their reply */ 2034 if (mux_client_read_packet(fd, &m) != 0) { 2035 buffer_free(&m); 2036 return 0; 2037 } 2038 type = buffer_get_int(&m); 2039 if (type != MUX_S_PROXY) { 2040 e = buffer_get_string(&m, NULL); 2041 fatal("%s: master returned error: %s", __func__, e); 2042 } 2043 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2044 fatal("%s: out of sequence reply: my id %u theirs %u", 2045 __func__, muxclient_request_id, rid); 2046 buffer_free(&m); 2047 2048 debug3("%s: done", __func__); 2049 muxclient_request_id++; 2050 return 0; 2051 } 2052 2053 static int 2054 mux_client_request_stdio_fwd(int fd) 2055 { 2056 Buffer m; 2057 char *e; 2058 u_int type, rid, sid; 2059 int devnull; 2060 2061 debug3("%s: entering", __func__); 2062 2063 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2064 error("%s: master alive request failed", __func__); 2065 return -1; 2066 } 2067 2068 signal(SIGPIPE, SIG_IGN); 2069 2070 if (stdin_null_flag) { 2071 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 2072 fatal("open(/dev/null): %s", strerror(errno)); 2073 if (dup2(devnull, STDIN_FILENO) == -1) 2074 fatal("dup2: %s", strerror(errno)); 2075 if (devnull > STDERR_FILENO) 2076 close(devnull); 2077 } 2078 2079 buffer_init(&m); 2080 buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); 2081 buffer_put_int(&m, muxclient_request_id); 2082 buffer_put_cstring(&m, ""); /* reserved */ 2083 buffer_put_cstring(&m, options.stdio_forward_host); 2084 buffer_put_int(&m, options.stdio_forward_port); 2085 2086 if (mux_client_write_packet(fd, &m) != 0) 2087 fatal("%s: write packet: %s", __func__, strerror(errno)); 2088 2089 /* Send the stdio file descriptors */ 2090 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2091 mm_send_fd(fd, STDOUT_FILENO) == -1) 2092 fatal("%s: send fds failed", __func__); 2093 2094 if (pledge("stdio proc tty", NULL) == -1) 2095 fatal("%s pledge(): %s", __func__, strerror(errno)); 2096 platform_pledge_mux(); 2097 2098 debug3("%s: stdio forward request sent", __func__); 2099 2100 /* Read their reply */ 2101 buffer_clear(&m); 2102 2103 if (mux_client_read_packet(fd, &m) != 0) { 2104 error("%s: read from master failed: %s", 2105 __func__, strerror(errno)); 2106 buffer_free(&m); 2107 return -1; 2108 } 2109 2110 type = buffer_get_int(&m); 2111 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2112 fatal("%s: out of sequence reply: my id %u theirs %u", 2113 __func__, muxclient_request_id, rid); 2114 switch (type) { 2115 case MUX_S_SESSION_OPENED: 2116 sid = buffer_get_int(&m); 2117 debug("%s: master session id: %u", __func__, sid); 2118 break; 2119 case MUX_S_PERMISSION_DENIED: 2120 e = buffer_get_string(&m, NULL); 2121 buffer_free(&m); 2122 fatal("Master refused stdio forwarding request: %s", e); 2123 case MUX_S_FAILURE: 2124 e = buffer_get_string(&m, NULL); 2125 buffer_free(&m); 2126 fatal("Stdio forwarding request failed: %s", e); 2127 default: 2128 buffer_free(&m); 2129 error("%s: unexpected response from master 0x%08x", 2130 __func__, type); 2131 return -1; 2132 } 2133 muxclient_request_id++; 2134 2135 signal(SIGHUP, control_client_sighandler); 2136 signal(SIGINT, control_client_sighandler); 2137 signal(SIGTERM, control_client_sighandler); 2138 signal(SIGWINCH, control_client_sigrelay); 2139 2140 /* 2141 * Stick around until the controlee closes the client_fd. 2142 */ 2143 buffer_clear(&m); 2144 if (mux_client_read_packet(fd, &m) != 0) { 2145 if (errno == EPIPE || 2146 (errno == EINTR && muxclient_terminate != 0)) 2147 return 0; 2148 fatal("%s: mux_client_read_packet: %s", 2149 __func__, strerror(errno)); 2150 } 2151 fatal("%s: master returned unexpected message %u", __func__, type); 2152 } 2153 2154 static void 2155 mux_client_request_stop_listening(int fd) 2156 { 2157 Buffer m; 2158 char *e; 2159 u_int type, rid; 2160 2161 debug3("%s: entering", __func__); 2162 2163 buffer_init(&m); 2164 buffer_put_int(&m, MUX_C_STOP_LISTENING); 2165 buffer_put_int(&m, muxclient_request_id); 2166 2167 if (mux_client_write_packet(fd, &m) != 0) 2168 fatal("%s: write packet: %s", __func__, strerror(errno)); 2169 2170 buffer_clear(&m); 2171 2172 /* Read their reply */ 2173 if (mux_client_read_packet(fd, &m) != 0) 2174 fatal("%s: read from master failed: %s", 2175 __func__, strerror(errno)); 2176 2177 type = buffer_get_int(&m); 2178 if ((rid = buffer_get_int(&m)) != muxclient_request_id) 2179 fatal("%s: out of sequence reply: my id %u theirs %u", 2180 __func__, muxclient_request_id, rid); 2181 switch (type) { 2182 case MUX_S_OK: 2183 break; 2184 case MUX_S_PERMISSION_DENIED: 2185 e = buffer_get_string(&m, NULL); 2186 fatal("Master refused stop listening request: %s", e); 2187 case MUX_S_FAILURE: 2188 e = buffer_get_string(&m, NULL); 2189 fatal("%s: stop listening request failed: %s", __func__, e); 2190 default: 2191 fatal("%s: unexpected response from master 0x%08x", 2192 __func__, type); 2193 } 2194 buffer_free(&m); 2195 muxclient_request_id++; 2196 } 2197 2198 /* Multiplex client main loop. */ 2199 int 2200 muxclient(const char *path) 2201 { 2202 struct sockaddr_un addr; 2203 int sock; 2204 u_int pid; 2205 2206 if (muxclient_command == 0) { 2207 if (options.stdio_forward_host != NULL) 2208 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2209 else 2210 muxclient_command = SSHMUX_COMMAND_OPEN; 2211 } 2212 2213 switch (options.control_master) { 2214 case SSHCTL_MASTER_AUTO: 2215 case SSHCTL_MASTER_AUTO_ASK: 2216 debug("auto-mux: Trying existing master"); 2217 /* FALLTHROUGH */ 2218 case SSHCTL_MASTER_NO: 2219 break; 2220 default: 2221 return -1; 2222 } 2223 2224 memset(&addr, '\0', sizeof(addr)); 2225 addr.sun_family = AF_UNIX; 2226 2227 if (strlcpy(addr.sun_path, path, 2228 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2229 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2230 (unsigned int)sizeof(addr.sun_path)); 2231 2232 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2233 fatal("%s socket(): %s", __func__, strerror(errno)); 2234 2235 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2236 switch (muxclient_command) { 2237 case SSHMUX_COMMAND_OPEN: 2238 case SSHMUX_COMMAND_STDIO_FWD: 2239 break; 2240 default: 2241 fatal("Control socket connect(%.100s): %s", path, 2242 strerror(errno)); 2243 } 2244 if (errno == ECONNREFUSED && 2245 options.control_master != SSHCTL_MASTER_NO) { 2246 debug("Stale control socket %.100s, unlinking", path); 2247 unlink(path); 2248 } else if (errno == ENOENT) { 2249 debug("Control socket \"%.100s\" does not exist", path); 2250 } else { 2251 error("Control socket connect(%.100s): %s", path, 2252 strerror(errno)); 2253 } 2254 close(sock); 2255 return -1; 2256 } 2257 set_nonblock(sock); 2258 2259 if (mux_client_hello_exchange(sock) != 0) { 2260 error("%s: master hello exchange failed", __func__); 2261 close(sock); 2262 return -1; 2263 } 2264 2265 switch (muxclient_command) { 2266 case SSHMUX_COMMAND_ALIVE_CHECK: 2267 if ((pid = mux_client_request_alive(sock)) == 0) 2268 fatal("%s: master alive check failed", __func__); 2269 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2270 exit(0); 2271 case SSHMUX_COMMAND_TERMINATE: 2272 mux_client_request_terminate(sock); 2273 if (options.log_level != SYSLOG_LEVEL_QUIET) 2274 fprintf(stderr, "Exit request sent.\r\n"); 2275 exit(0); 2276 case SSHMUX_COMMAND_FORWARD: 2277 if (mux_client_forwards(sock, 0) != 0) 2278 fatal("%s: master forward request failed", __func__); 2279 exit(0); 2280 case SSHMUX_COMMAND_OPEN: 2281 if (mux_client_forwards(sock, 0) != 0) { 2282 error("%s: master forward request failed", __func__); 2283 return -1; 2284 } 2285 mux_client_request_session(sock); 2286 return -1; 2287 case SSHMUX_COMMAND_STDIO_FWD: 2288 mux_client_request_stdio_fwd(sock); 2289 exit(0); 2290 case SSHMUX_COMMAND_STOP: 2291 mux_client_request_stop_listening(sock); 2292 if (options.log_level != SYSLOG_LEVEL_QUIET) 2293 fprintf(stderr, "Stop listening request sent.\r\n"); 2294 exit(0); 2295 case SSHMUX_COMMAND_CANCEL_FWD: 2296 if (mux_client_forwards(sock, 1) != 0) 2297 error("%s: master cancel forward request failed", 2298 __func__); 2299 exit(0); 2300 case SSHMUX_COMMAND_PROXY: 2301 mux_client_proxy(sock); 2302 return (sock); 2303 default: 2304 fatal("unrecognised muxclient_command %d", muxclient_command); 2305 } 2306 } 2307