1 /* $OpenBSD: mux.c,v 1.75 2018/07/31 03:07:24 djm Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 /* 21 * TODO: 22 * - Better signalling from master to slave, especially passing of 23 * error messages 24 * - Better fall-back from mux slave error to new connection. 25 * - ExitOnForwardingFailure 26 * - Maybe extension mechanisms for multi-X11/multi-agent forwarding 27 * - Support ~^Z in mux slaves. 28 * - Inspect or control sessions in master. 29 * - If we ever support the "signal" channel request, send signals on 30 * sessions in master. 31 */ 32 33 #include "includes.h" 34 __RCSID("$FreeBSD$"); 35 36 #include <sys/types.h> 37 #include <sys/stat.h> 38 #include <sys/socket.h> 39 #include <sys/un.h> 40 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <signal.h> 44 #include <stdarg.h> 45 #include <stddef.h> 46 #include <stdlib.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <unistd.h> 50 #ifdef HAVE_PATHS_H 51 #include <paths.h> 52 #endif 53 54 #ifdef HAVE_POLL_H 55 #include <poll.h> 56 #else 57 # ifdef HAVE_SYS_POLL_H 58 # include <sys/poll.h> 59 # endif 60 #endif 61 62 #ifdef HAVE_UTIL_H 63 # include <util.h> 64 #endif 65 66 #include "openbsd-compat/sys-queue.h" 67 #include "xmalloc.h" 68 #include "log.h" 69 #include "ssh.h" 70 #include "ssh2.h" 71 #include "pathnames.h" 72 #include "misc.h" 73 #include "match.h" 74 #include "sshbuf.h" 75 #include "channels.h" 76 #include "msg.h" 77 #include "packet.h" 78 #include "monitor_fdpass.h" 79 #include "sshpty.h" 80 #include "sshkey.h" 81 #include "readconf.h" 82 #include "clientloop.h" 83 #include "ssherr.h" 84 85 /* from ssh.c */ 86 extern int tty_flag; 87 extern Options options; 88 extern int stdin_null_flag; 89 extern char *host; 90 extern int subsystem_flag; 91 extern struct sshbuf *command; 92 extern volatile sig_atomic_t quit_pending; 93 94 /* Context for session open confirmation callback */ 95 struct mux_session_confirm_ctx { 96 u_int want_tty; 97 u_int want_subsys; 98 u_int want_x_fwd; 99 u_int want_agent_fwd; 100 struct sshbuf *cmd; 101 char *term; 102 struct termios tio; 103 char **env; 104 u_int rid; 105 }; 106 107 /* Context for stdio fwd open confirmation callback */ 108 struct mux_stdio_confirm_ctx { 109 u_int rid; 110 }; 111 112 /* Context for global channel callback */ 113 struct mux_channel_confirm_ctx { 114 u_int cid; /* channel id */ 115 u_int rid; /* request id */ 116 int fid; /* forward id */ 117 }; 118 119 /* fd to control socket */ 120 int muxserver_sock = -1; 121 122 /* client request id */ 123 u_int muxclient_request_id = 0; 124 125 /* Multiplexing control command */ 126 u_int muxclient_command = 0; 127 128 /* Set when signalled. */ 129 static volatile sig_atomic_t muxclient_terminate = 0; 130 131 /* PID of multiplex server */ 132 static u_int muxserver_pid = 0; 133 134 static Channel *mux_listener_channel = NULL; 135 136 struct mux_master_state { 137 int hello_rcvd; 138 }; 139 140 /* mux protocol messages */ 141 #define MUX_MSG_HELLO 0x00000001 142 #define MUX_C_NEW_SESSION 0x10000002 143 #define MUX_C_ALIVE_CHECK 0x10000004 144 #define MUX_C_TERMINATE 0x10000005 145 #define MUX_C_OPEN_FWD 0x10000006 146 #define MUX_C_CLOSE_FWD 0x10000007 147 #define MUX_C_NEW_STDIO_FWD 0x10000008 148 #define MUX_C_STOP_LISTENING 0x10000009 149 #define MUX_C_PROXY 0x1000000f 150 #define MUX_S_OK 0x80000001 151 #define MUX_S_PERMISSION_DENIED 0x80000002 152 #define MUX_S_FAILURE 0x80000003 153 #define MUX_S_EXIT_MESSAGE 0x80000004 154 #define MUX_S_ALIVE 0x80000005 155 #define MUX_S_SESSION_OPENED 0x80000006 156 #define MUX_S_REMOTE_PORT 0x80000007 157 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 158 #define MUX_S_PROXY 0x8000000f 159 160 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 161 #define MUX_FWD_LOCAL 1 162 #define MUX_FWD_REMOTE 2 163 #define MUX_FWD_DYNAMIC 3 164 165 static void mux_session_confirm(struct ssh *, int, int, void *); 166 static void mux_stdio_confirm(struct ssh *, int, int, void *); 167 168 static int process_mux_master_hello(struct ssh *, u_int, 169 Channel *, struct sshbuf *, struct sshbuf *); 170 static int process_mux_new_session(struct ssh *, u_int, 171 Channel *, struct sshbuf *, struct sshbuf *); 172 static int process_mux_alive_check(struct ssh *, u_int, 173 Channel *, struct sshbuf *, struct sshbuf *); 174 static int process_mux_terminate(struct ssh *, u_int, 175 Channel *, struct sshbuf *, struct sshbuf *); 176 static int process_mux_open_fwd(struct ssh *, u_int, 177 Channel *, struct sshbuf *, struct sshbuf *); 178 static int process_mux_close_fwd(struct ssh *, u_int, 179 Channel *, struct sshbuf *, struct sshbuf *); 180 static int process_mux_stdio_fwd(struct ssh *, u_int, 181 Channel *, struct sshbuf *, struct sshbuf *); 182 static int process_mux_stop_listening(struct ssh *, u_int, 183 Channel *, struct sshbuf *, struct sshbuf *); 184 static int process_mux_proxy(struct ssh *, u_int, 185 Channel *, struct sshbuf *, struct sshbuf *); 186 187 static const struct { 188 u_int type; 189 int (*handler)(struct ssh *, u_int, Channel *, 190 struct sshbuf *, struct sshbuf *); 191 } mux_master_handlers[] = { 192 { MUX_MSG_HELLO, process_mux_master_hello }, 193 { MUX_C_NEW_SESSION, process_mux_new_session }, 194 { MUX_C_ALIVE_CHECK, process_mux_alive_check }, 195 { MUX_C_TERMINATE, process_mux_terminate }, 196 { MUX_C_OPEN_FWD, process_mux_open_fwd }, 197 { MUX_C_CLOSE_FWD, process_mux_close_fwd }, 198 { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, 199 { MUX_C_STOP_LISTENING, process_mux_stop_listening }, 200 { MUX_C_PROXY, process_mux_proxy }, 201 { 0, NULL } 202 }; 203 204 /* Cleanup callback fired on closure of mux slave _session_ channel */ 205 /* ARGSUSED */ 206 static void 207 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused) 208 { 209 Channel *cc, *c = channel_by_id(ssh, cid); 210 211 debug3("%s: entering for channel %d", __func__, cid); 212 if (c == NULL) 213 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 214 if (c->ctl_chan != -1) { 215 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 216 fatal("%s: channel %d missing control channel %d", 217 __func__, c->self, c->ctl_chan); 218 c->ctl_chan = -1; 219 cc->remote_id = 0; 220 cc->have_remote_id = 0; 221 chan_rcvd_oclose(ssh, cc); 222 } 223 channel_cancel_cleanup(ssh, c->self); 224 } 225 226 /* Cleanup callback fired on closure of mux slave _control_ channel */ 227 /* ARGSUSED */ 228 static void 229 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused) 230 { 231 Channel *sc, *c = channel_by_id(ssh, cid); 232 233 debug3("%s: entering for channel %d", __func__, cid); 234 if (c == NULL) 235 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 236 if (c->have_remote_id) { 237 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 238 fatal("%s: channel %d missing session channel %u", 239 __func__, c->self, c->remote_id); 240 c->remote_id = 0; 241 c->have_remote_id = 0; 242 sc->ctl_chan = -1; 243 if (sc->type != SSH_CHANNEL_OPEN && 244 sc->type != SSH_CHANNEL_OPENING) { 245 debug2("%s: channel %d: not open", __func__, sc->self); 246 chan_mark_dead(ssh, sc); 247 } else { 248 if (sc->istate == CHAN_INPUT_OPEN) 249 chan_read_failed(ssh, sc); 250 if (sc->ostate == CHAN_OUTPUT_OPEN) 251 chan_write_failed(ssh, sc); 252 } 253 } 254 channel_cancel_cleanup(ssh, c->self); 255 } 256 257 /* Check mux client environment variables before passing them to mux master. */ 258 static int 259 env_permitted(char *env) 260 { 261 int i, ret; 262 char name[1024], *cp; 263 264 if ((cp = strchr(env, '=')) == NULL || cp == env) 265 return 0; 266 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 267 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 268 error("env_permitted: name '%.100s...' too long", env); 269 return 0; 270 } 271 272 for (i = 0; i < options.num_send_env; i++) 273 if (match_pattern(name, options.send_env[i])) 274 return 1; 275 276 return 0; 277 } 278 279 /* Mux master protocol message handlers */ 280 281 static int 282 process_mux_master_hello(struct ssh *ssh, u_int rid, 283 Channel *c, struct sshbuf *m, struct sshbuf *reply) 284 { 285 u_int ver; 286 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 287 int r; 288 289 if (state == NULL) 290 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 291 if (state->hello_rcvd) { 292 error("%s: HELLO received twice", __func__); 293 return -1; 294 } 295 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 296 error("%s: malformed message: %s", __func__, ssh_err(r)); 297 return -1; 298 } 299 if (ver != SSHMUX_VER) { 300 error("Unsupported multiplexing protocol version %d " 301 "(expected %d)", ver, SSHMUX_VER); 302 return -1; 303 } 304 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 305 306 /* No extensions are presently defined */ 307 while (sshbuf_len(m) > 0) { 308 char *name = NULL; 309 310 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 311 (r = sshbuf_skip_string(m)) != 0) { /* value */ 312 error("%s: malformed extension: %s", 313 __func__, ssh_err(r)); 314 return -1; 315 } 316 debug2("Unrecognised slave extension \"%s\"", name); 317 free(name); 318 } 319 state->hello_rcvd = 1; 320 return 0; 321 } 322 323 /* Enqueue a "ok" response to the reply buffer */ 324 static void 325 reply_ok(struct sshbuf *reply, u_int rid) 326 { 327 int r; 328 329 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 330 (r = sshbuf_put_u32(reply, rid)) != 0) 331 fatal("%s: reply: %s", __func__, ssh_err(r)); 332 } 333 334 /* Enqueue an error response to the reply buffer */ 335 static void 336 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 337 { 338 int r; 339 340 if ((r = sshbuf_put_u32(reply, type)) != 0 || 341 (r = sshbuf_put_u32(reply, rid)) != 0 || 342 (r = sshbuf_put_cstring(reply, msg)) != 0) 343 fatal("%s: reply: %s", __func__, ssh_err(r)); 344 } 345 346 static int 347 process_mux_new_session(struct ssh *ssh, u_int rid, 348 Channel *c, struct sshbuf *m, struct sshbuf *reply) 349 { 350 Channel *nc; 351 struct mux_session_confirm_ctx *cctx; 352 char *cmd, *cp; 353 u_int i, j, env_len, escape_char, window, packetmax; 354 int r, new_fd[3]; 355 356 /* Reply for SSHMUX_COMMAND_OPEN */ 357 cctx = xcalloc(1, sizeof(*cctx)); 358 cctx->term = NULL; 359 cctx->rid = rid; 360 cmd = NULL; 361 cctx->env = NULL; 362 env_len = 0; 363 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 364 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 365 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 366 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 367 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 368 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 369 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 370 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 371 malf: 372 free(cmd); 373 for (j = 0; j < env_len; j++) 374 free(cctx->env[j]); 375 free(cctx->env); 376 free(cctx->term); 377 free(cctx); 378 error("%s: malformed message", __func__); 379 return -1; 380 } 381 382 #define MUX_MAX_ENV_VARS 4096 383 while (sshbuf_len(m) > 0) { 384 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 385 goto malf; 386 if (!env_permitted(cp)) { 387 free(cp); 388 continue; 389 } 390 cctx->env = xreallocarray(cctx->env, env_len + 2, 391 sizeof(*cctx->env)); 392 cctx->env[env_len++] = cp; 393 cctx->env[env_len] = NULL; 394 if (env_len > MUX_MAX_ENV_VARS) { 395 error(">%d environment variables received, ignoring " 396 "additional", MUX_MAX_ENV_VARS); 397 break; 398 } 399 } 400 401 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 402 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 403 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 404 cctx->want_subsys, cctx->term, cmd, env_len); 405 406 if ((cctx->cmd = sshbuf_new()) == NULL) 407 fatal("%s: sshbuf_new", __func__); 408 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 409 fatal("%s: sshbuf_put: %s", __func__, ssh_err(r)); 410 free(cmd); 411 cmd = NULL; 412 413 /* Gather fds from client */ 414 for(i = 0; i < 3; i++) { 415 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 416 error("%s: failed to receive fd %d from slave", 417 __func__, i); 418 for (j = 0; j < i; j++) 419 close(new_fd[j]); 420 for (j = 0; j < env_len; j++) 421 free(cctx->env[j]); 422 free(cctx->env); 423 free(cctx->term); 424 sshbuf_free(cctx->cmd); 425 free(cctx); 426 reply_error(reply, MUX_S_FAILURE, rid, 427 "did not receive file descriptors"); 428 return -1; 429 } 430 } 431 432 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 433 new_fd[0], new_fd[1], new_fd[2]); 434 435 /* XXX support multiple child sessions in future */ 436 if (c->have_remote_id) { 437 debug2("%s: session already open", __func__); 438 reply_error(reply, MUX_S_FAILURE, rid, 439 "Multiple sessions not supported"); 440 cleanup: 441 close(new_fd[0]); 442 close(new_fd[1]); 443 close(new_fd[2]); 444 free(cctx->term); 445 if (env_len != 0) { 446 for (i = 0; i < env_len; i++) 447 free(cctx->env[i]); 448 free(cctx->env); 449 } 450 sshbuf_free(cctx->cmd); 451 free(cctx); 452 return 0; 453 } 454 455 if (options.control_master == SSHCTL_MASTER_ASK || 456 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 457 if (!ask_permission("Allow shared connection to %s? ", host)) { 458 debug2("%s: session refused by user", __func__); 459 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 460 "Permission denied"); 461 goto cleanup; 462 } 463 } 464 465 /* Try to pick up ttymodes from client before it goes raw */ 466 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 467 error("%s: tcgetattr: %s", __func__, strerror(errno)); 468 469 /* enable nonblocking unless tty */ 470 if (!isatty(new_fd[0])) 471 set_nonblock(new_fd[0]); 472 if (!isatty(new_fd[1])) 473 set_nonblock(new_fd[1]); 474 if (!isatty(new_fd[2])) 475 set_nonblock(new_fd[2]); 476 477 window = CHAN_SES_WINDOW_DEFAULT; 478 packetmax = CHAN_SES_PACKET_DEFAULT; 479 if (cctx->want_tty) { 480 window >>= 1; 481 packetmax >>= 1; 482 } 483 484 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 485 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 486 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 487 488 nc->ctl_chan = c->self; /* link session -> control channel */ 489 c->remote_id = nc->self; /* link control -> session channel */ 490 c->have_remote_id = 1; 491 492 if (cctx->want_tty && escape_char != 0xffffffff) { 493 channel_register_filter(ssh, nc->self, 494 client_simple_escape_filter, NULL, 495 client_filter_cleanup, 496 client_new_escape_filter_ctx((int)escape_char)); 497 } 498 499 debug2("%s: channel_new: %d linked to control channel %d", 500 __func__, nc->self, nc->ctl_chan); 501 502 channel_send_open(ssh, nc->self); 503 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 504 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 505 channel_register_cleanup(ssh, nc->self, 506 mux_master_session_cleanup_cb, 1); 507 508 /* reply is deferred, sent by mux_session_confirm */ 509 return 0; 510 } 511 512 static int 513 process_mux_alive_check(struct ssh *ssh, u_int rid, 514 Channel *c, struct sshbuf *m, struct sshbuf *reply) 515 { 516 int r; 517 518 debug2("%s: channel %d: alive check", __func__, c->self); 519 520 /* prepare reply */ 521 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 522 (r = sshbuf_put_u32(reply, rid)) != 0 || 523 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 524 fatal("%s: reply: %s", __func__, ssh_err(r)); 525 526 return 0; 527 } 528 529 static int 530 process_mux_terminate(struct ssh *ssh, u_int rid, 531 Channel *c, struct sshbuf *m, struct sshbuf *reply) 532 { 533 debug2("%s: channel %d: terminate request", __func__, c->self); 534 535 if (options.control_master == SSHCTL_MASTER_ASK || 536 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 537 if (!ask_permission("Terminate shared connection to %s? ", 538 host)) { 539 debug2("%s: termination refused by user", __func__); 540 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 541 "Permission denied"); 542 return 0; 543 } 544 } 545 546 quit_pending = 1; 547 reply_ok(reply, rid); 548 /* XXX exit happens too soon - message never makes it to client */ 549 return 0; 550 } 551 552 static char * 553 format_forward(u_int ftype, struct Forward *fwd) 554 { 555 char *ret; 556 557 switch (ftype) { 558 case MUX_FWD_LOCAL: 559 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 560 (fwd->listen_path != NULL) ? fwd->listen_path : 561 (fwd->listen_host == NULL) ? 562 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 563 fwd->listen_host, fwd->listen_port, 564 (fwd->connect_path != NULL) ? fwd->connect_path : 565 fwd->connect_host, fwd->connect_port); 566 break; 567 case MUX_FWD_DYNAMIC: 568 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 569 (fwd->listen_host == NULL) ? 570 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 571 fwd->listen_host, fwd->listen_port); 572 break; 573 case MUX_FWD_REMOTE: 574 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 575 (fwd->listen_path != NULL) ? fwd->listen_path : 576 (fwd->listen_host == NULL) ? 577 "LOCALHOST" : fwd->listen_host, 578 fwd->listen_port, 579 (fwd->connect_path != NULL) ? fwd->connect_path : 580 fwd->connect_host, fwd->connect_port); 581 break; 582 default: 583 fatal("%s: unknown forward type %u", __func__, ftype); 584 } 585 return ret; 586 } 587 588 static int 589 compare_host(const char *a, const char *b) 590 { 591 if (a == NULL && b == NULL) 592 return 1; 593 if (a == NULL || b == NULL) 594 return 0; 595 return strcmp(a, b) == 0; 596 } 597 598 static int 599 compare_forward(struct Forward *a, struct Forward *b) 600 { 601 if (!compare_host(a->listen_host, b->listen_host)) 602 return 0; 603 if (!compare_host(a->listen_path, b->listen_path)) 604 return 0; 605 if (a->listen_port != b->listen_port) 606 return 0; 607 if (!compare_host(a->connect_host, b->connect_host)) 608 return 0; 609 if (!compare_host(a->connect_path, b->connect_path)) 610 return 0; 611 if (a->connect_port != b->connect_port) 612 return 0; 613 614 return 1; 615 } 616 617 static void 618 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 619 { 620 struct mux_channel_confirm_ctx *fctx = ctxt; 621 char *failmsg = NULL; 622 struct Forward *rfwd; 623 Channel *c; 624 struct sshbuf *out; 625 int r; 626 627 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 628 /* no channel for reply */ 629 error("%s: unknown channel", __func__); 630 return; 631 } 632 if ((out = sshbuf_new()) == NULL) 633 fatal("%s: sshbuf_new", __func__); 634 if (fctx->fid >= options.num_remote_forwards || 635 (options.remote_forwards[fctx->fid].connect_path == NULL && 636 options.remote_forwards[fctx->fid].connect_host == NULL)) { 637 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 638 goto fail; 639 } 640 rfwd = &options.remote_forwards[fctx->fid]; 641 debug("%s: %s for: listen %d, connect %s:%d", __func__, 642 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 643 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 644 rfwd->connect_host, rfwd->connect_port); 645 if (type == SSH2_MSG_REQUEST_SUCCESS) { 646 if (rfwd->listen_port == 0) { 647 rfwd->allocated_port = packet_get_int(); 648 debug("Allocated port %u for mux remote forward" 649 " to %s:%d", rfwd->allocated_port, 650 rfwd->connect_host, rfwd->connect_port); 651 if ((r = sshbuf_put_u32(out, 652 MUX_S_REMOTE_PORT)) != 0 || 653 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 654 (r = sshbuf_put_u32(out, 655 rfwd->allocated_port)) != 0) 656 fatal("%s: reply: %s", __func__, ssh_err(r)); 657 channel_update_permission(ssh, rfwd->handle, 658 rfwd->allocated_port); 659 } else { 660 reply_ok(out, fctx->rid); 661 } 662 goto out; 663 } else { 664 if (rfwd->listen_port == 0) 665 channel_update_permission(ssh, rfwd->handle, -1); 666 if (rfwd->listen_path != NULL) 667 xasprintf(&failmsg, "remote port forwarding failed for " 668 "listen path %s", rfwd->listen_path); 669 else 670 xasprintf(&failmsg, "remote port forwarding failed for " 671 "listen port %d", rfwd->listen_port); 672 673 debug2("%s: clearing registered forwarding for listen %d, " 674 "connect %s:%d", __func__, rfwd->listen_port, 675 rfwd->connect_path ? rfwd->connect_path : 676 rfwd->connect_host, rfwd->connect_port); 677 678 free(rfwd->listen_host); 679 free(rfwd->listen_path); 680 free(rfwd->connect_host); 681 free(rfwd->connect_path); 682 memset(rfwd, 0, sizeof(*rfwd)); 683 } 684 fail: 685 error("%s: %s", __func__, failmsg); 686 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 687 free(failmsg); 688 out: 689 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 690 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 691 sshbuf_free(out); 692 if (c->mux_pause <= 0) 693 fatal("%s: mux_pause %d", __func__, c->mux_pause); 694 c->mux_pause = 0; /* start processing messages again */ 695 } 696 697 static int 698 process_mux_open_fwd(struct ssh *ssh, u_int rid, 699 Channel *c, struct sshbuf *m, struct sshbuf *reply) 700 { 701 struct Forward fwd; 702 char *fwd_desc = NULL; 703 char *listen_addr, *connect_addr; 704 u_int ftype; 705 u_int lport, cport; 706 int r, i, ret = 0, freefwd = 1; 707 708 memset(&fwd, 0, sizeof(fwd)); 709 710 /* XXX - lport/cport check redundant */ 711 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 712 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 713 (r = sshbuf_get_u32(m, &lport)) != 0 || 714 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 715 (r = sshbuf_get_u32(m, &cport)) != 0 || 716 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 717 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 718 error("%s: malformed message", __func__); 719 ret = -1; 720 goto out; 721 } 722 if (*listen_addr == '\0') { 723 free(listen_addr); 724 listen_addr = NULL; 725 } 726 if (*connect_addr == '\0') { 727 free(connect_addr); 728 connect_addr = NULL; 729 } 730 731 memset(&fwd, 0, sizeof(fwd)); 732 fwd.listen_port = lport; 733 if (fwd.listen_port == PORT_STREAMLOCAL) 734 fwd.listen_path = listen_addr; 735 else 736 fwd.listen_host = listen_addr; 737 fwd.connect_port = cport; 738 if (fwd.connect_port == PORT_STREAMLOCAL) 739 fwd.connect_path = connect_addr; 740 else 741 fwd.connect_host = connect_addr; 742 743 debug2("%s: channel %d: request %s", __func__, c->self, 744 (fwd_desc = format_forward(ftype, &fwd))); 745 746 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 747 ftype != MUX_FWD_DYNAMIC) { 748 logit("%s: invalid forwarding type %u", __func__, ftype); 749 invalid: 750 free(listen_addr); 751 free(connect_addr); 752 reply_error(reply, MUX_S_FAILURE, rid, 753 "Invalid forwarding request"); 754 return 0; 755 } 756 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 757 logit("%s: streamlocal and dynamic forwards " 758 "are mutually exclusive", __func__); 759 goto invalid; 760 } 761 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 762 logit("%s: invalid listen port %u", __func__, 763 fwd.listen_port); 764 goto invalid; 765 } 766 if ((fwd.connect_port != PORT_STREAMLOCAL && 767 fwd.connect_port >= 65536) || 768 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 769 fwd.connect_port == 0)) { 770 logit("%s: invalid connect port %u", __func__, 771 fwd.connect_port); 772 goto invalid; 773 } 774 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 775 fwd.connect_path == NULL) { 776 logit("%s: missing connect host", __func__); 777 goto invalid; 778 } 779 780 /* Skip forwards that have already been requested */ 781 switch (ftype) { 782 case MUX_FWD_LOCAL: 783 case MUX_FWD_DYNAMIC: 784 for (i = 0; i < options.num_local_forwards; i++) { 785 if (compare_forward(&fwd, 786 options.local_forwards + i)) { 787 exists: 788 debug2("%s: found existing forwarding", 789 __func__); 790 reply_ok(reply, rid); 791 goto out; 792 } 793 } 794 break; 795 case MUX_FWD_REMOTE: 796 for (i = 0; i < options.num_remote_forwards; i++) { 797 if (!compare_forward(&fwd, options.remote_forwards + i)) 798 continue; 799 if (fwd.listen_port != 0) 800 goto exists; 801 debug2("%s: found allocated port", __func__); 802 if ((r = sshbuf_put_u32(reply, 803 MUX_S_REMOTE_PORT)) != 0 || 804 (r = sshbuf_put_u32(reply, rid)) != 0 || 805 (r = sshbuf_put_u32(reply, 806 options.remote_forwards[i].allocated_port)) != 0) 807 fatal("%s: reply: %s", __func__, ssh_err(r)); 808 goto out; 809 } 810 break; 811 } 812 813 if (options.control_master == SSHCTL_MASTER_ASK || 814 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 815 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 816 debug2("%s: forwarding refused by user", __func__); 817 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 818 "Permission denied"); 819 goto out; 820 } 821 } 822 823 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 824 if (!channel_setup_local_fwd_listener(ssh, &fwd, 825 &options.fwd_opts)) { 826 fail: 827 logit("slave-requested %s failed", fwd_desc); 828 reply_error(reply, MUX_S_FAILURE, rid, 829 "Port forwarding failed"); 830 goto out; 831 } 832 add_local_forward(&options, &fwd); 833 freefwd = 0; 834 } else { 835 struct mux_channel_confirm_ctx *fctx; 836 837 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 838 if (fwd.handle < 0) 839 goto fail; 840 add_remote_forward(&options, &fwd); 841 fctx = xcalloc(1, sizeof(*fctx)); 842 fctx->cid = c->self; 843 fctx->rid = rid; 844 fctx->fid = options.num_remote_forwards - 1; 845 client_register_global_confirm(mux_confirm_remote_forward, 846 fctx); 847 freefwd = 0; 848 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 849 /* delayed reply in mux_confirm_remote_forward */ 850 goto out; 851 } 852 reply_ok(reply, rid); 853 out: 854 free(fwd_desc); 855 if (freefwd) { 856 free(fwd.listen_host); 857 free(fwd.listen_path); 858 free(fwd.connect_host); 859 free(fwd.connect_path); 860 } 861 return ret; 862 } 863 864 static int 865 process_mux_close_fwd(struct ssh *ssh, u_int rid, 866 Channel *c, struct sshbuf *m, struct sshbuf *reply) 867 { 868 struct Forward fwd, *found_fwd; 869 char *fwd_desc = NULL; 870 const char *error_reason = NULL; 871 char *listen_addr = NULL, *connect_addr = NULL; 872 u_int ftype; 873 int r, i, ret = 0; 874 u_int lport, cport; 875 876 memset(&fwd, 0, sizeof(fwd)); 877 878 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 879 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 880 (r = sshbuf_get_u32(m, &lport)) != 0 || 881 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 882 (r = sshbuf_get_u32(m, &cport)) != 0 || 883 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 884 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 885 error("%s: malformed message", __func__); 886 ret = -1; 887 goto out; 888 } 889 890 if (*listen_addr == '\0') { 891 free(listen_addr); 892 listen_addr = NULL; 893 } 894 if (*connect_addr == '\0') { 895 free(connect_addr); 896 connect_addr = NULL; 897 } 898 899 memset(&fwd, 0, sizeof(fwd)); 900 fwd.listen_port = lport; 901 if (fwd.listen_port == PORT_STREAMLOCAL) 902 fwd.listen_path = listen_addr; 903 else 904 fwd.listen_host = listen_addr; 905 fwd.connect_port = cport; 906 if (fwd.connect_port == PORT_STREAMLOCAL) 907 fwd.connect_path = connect_addr; 908 else 909 fwd.connect_host = connect_addr; 910 911 debug2("%s: channel %d: request cancel %s", __func__, c->self, 912 (fwd_desc = format_forward(ftype, &fwd))); 913 914 /* make sure this has been requested */ 915 found_fwd = NULL; 916 switch (ftype) { 917 case MUX_FWD_LOCAL: 918 case MUX_FWD_DYNAMIC: 919 for (i = 0; i < options.num_local_forwards; i++) { 920 if (compare_forward(&fwd, 921 options.local_forwards + i)) { 922 found_fwd = options.local_forwards + i; 923 break; 924 } 925 } 926 break; 927 case MUX_FWD_REMOTE: 928 for (i = 0; i < options.num_remote_forwards; i++) { 929 if (compare_forward(&fwd, 930 options.remote_forwards + i)) { 931 found_fwd = options.remote_forwards + i; 932 break; 933 } 934 } 935 break; 936 } 937 938 if (found_fwd == NULL) 939 error_reason = "port not forwarded"; 940 else if (ftype == MUX_FWD_REMOTE) { 941 /* 942 * This shouldn't fail unless we confused the host/port 943 * between options.remote_forwards and permitted_opens. 944 * However, for dynamic allocated listen ports we need 945 * to use the actual listen port. 946 */ 947 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 948 error_reason = "port not in permitted opens"; 949 } else { /* local and dynamic forwards */ 950 /* Ditto */ 951 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 952 &options.fwd_opts) == -1) 953 error_reason = "port not found"; 954 } 955 956 if (error_reason != NULL) 957 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 958 else { 959 reply_ok(reply, rid); 960 free(found_fwd->listen_host); 961 free(found_fwd->listen_path); 962 free(found_fwd->connect_host); 963 free(found_fwd->connect_path); 964 found_fwd->listen_host = found_fwd->connect_host = NULL; 965 found_fwd->listen_path = found_fwd->connect_path = NULL; 966 found_fwd->listen_port = found_fwd->connect_port = 0; 967 } 968 out: 969 free(fwd_desc); 970 free(listen_addr); 971 free(connect_addr); 972 973 return ret; 974 } 975 976 static int 977 process_mux_stdio_fwd(struct ssh *ssh, u_int rid, 978 Channel *c, struct sshbuf *m, struct sshbuf *reply) 979 { 980 Channel *nc; 981 char *chost = NULL; 982 u_int cport, i, j; 983 int r, new_fd[2]; 984 struct mux_stdio_confirm_ctx *cctx; 985 986 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 987 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 988 (r = sshbuf_get_u32(m, &cport)) != 0) { 989 free(chost); 990 error("%s: malformed message", __func__); 991 return -1; 992 } 993 994 debug2("%s: channel %d: request stdio fwd to %s:%u", 995 __func__, c->self, chost, cport); 996 997 /* Gather fds from client */ 998 for(i = 0; i < 2; i++) { 999 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 1000 error("%s: failed to receive fd %d from slave", 1001 __func__, i); 1002 for (j = 0; j < i; j++) 1003 close(new_fd[j]); 1004 free(chost); 1005 1006 /* prepare reply */ 1007 reply_error(reply, MUX_S_FAILURE, rid, 1008 "did not receive file descriptors"); 1009 return -1; 1010 } 1011 } 1012 1013 debug3("%s: got fds stdin %d, stdout %d", __func__, 1014 new_fd[0], new_fd[1]); 1015 1016 /* XXX support multiple child sessions in future */ 1017 if (c->have_remote_id) { 1018 debug2("%s: session already open", __func__); 1019 reply_error(reply, MUX_S_FAILURE, rid, 1020 "Multiple sessions not supported"); 1021 cleanup: 1022 close(new_fd[0]); 1023 close(new_fd[1]); 1024 free(chost); 1025 return 0; 1026 } 1027 1028 if (options.control_master == SSHCTL_MASTER_ASK || 1029 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1030 if (!ask_permission("Allow forward to %s:%u? ", 1031 chost, cport)) { 1032 debug2("%s: stdio fwd refused by user", __func__); 1033 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1034 "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 free(chost); 1047 1048 nc->ctl_chan = c->self; /* link session -> control channel */ 1049 c->remote_id = nc->self; /* link control -> session channel */ 1050 c->have_remote_id = 1; 1051 1052 debug2("%s: channel_new: %d linked to control channel %d", 1053 __func__, nc->self, nc->ctl_chan); 1054 1055 channel_register_cleanup(ssh, nc->self, 1056 mux_master_session_cleanup_cb, 1); 1057 1058 cctx = xcalloc(1, sizeof(*cctx)); 1059 cctx->rid = rid; 1060 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1061 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1062 1063 /* reply is deferred, sent by mux_session_confirm */ 1064 return 0; 1065 } 1066 1067 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1068 static void 1069 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1070 { 1071 struct mux_stdio_confirm_ctx *cctx = arg; 1072 Channel *c, *cc; 1073 struct sshbuf *reply; 1074 int r; 1075 1076 if (cctx == NULL) 1077 fatal("%s: cctx == NULL", __func__); 1078 if ((c = channel_by_id(ssh, id)) == NULL) 1079 fatal("%s: no channel for id %d", __func__, id); 1080 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1081 fatal("%s: channel %d lacks control channel %d", __func__, 1082 id, c->ctl_chan); 1083 if ((reply = sshbuf_new()) == NULL) 1084 fatal("%s: sshbuf_new", __func__); 1085 1086 if (!success) { 1087 debug3("%s: sending failure reply", __func__); 1088 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1089 "Session open refused by peer"); 1090 /* prepare reply */ 1091 goto done; 1092 } 1093 1094 debug3("%s: sending success reply", __func__); 1095 /* prepare reply */ 1096 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1097 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1098 (r = sshbuf_put_u32(reply, c->self)) != 0) 1099 fatal("%s: reply: %s", __func__, ssh_err(r)); 1100 1101 done: 1102 /* Send reply */ 1103 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1104 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 1105 sshbuf_free(reply); 1106 1107 if (cc->mux_pause <= 0) 1108 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1109 cc->mux_pause = 0; /* start processing messages again */ 1110 c->open_confirm_ctx = NULL; 1111 free(cctx); 1112 } 1113 1114 static int 1115 process_mux_stop_listening(struct ssh *ssh, u_int rid, 1116 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1117 { 1118 debug("%s: channel %d: stop listening", __func__, c->self); 1119 1120 if (options.control_master == SSHCTL_MASTER_ASK || 1121 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1122 if (!ask_permission("Disable further multiplexing on shared " 1123 "connection to %s? ", host)) { 1124 debug2("%s: stop listen refused by user", __func__); 1125 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1126 "Permission denied"); 1127 return 0; 1128 } 1129 } 1130 1131 if (mux_listener_channel != NULL) { 1132 channel_free(ssh, mux_listener_channel); 1133 client_stop_mux(); 1134 free(options.control_path); 1135 options.control_path = NULL; 1136 mux_listener_channel = NULL; 1137 muxserver_sock = -1; 1138 } 1139 1140 reply_ok(reply, rid); 1141 return 0; 1142 } 1143 1144 static int 1145 process_mux_proxy(struct ssh *ssh, u_int rid, 1146 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1147 { 1148 int r; 1149 1150 debug("%s: channel %d: proxy request", __func__, c->self); 1151 1152 c->mux_rcb = channel_proxy_downstream; 1153 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1154 (r = sshbuf_put_u32(reply, rid)) != 0) 1155 fatal("%s: reply: %s", __func__, ssh_err(r)); 1156 1157 return 0; 1158 } 1159 1160 /* Channel callbacks fired on read/write from mux slave fd */ 1161 static int 1162 mux_master_read_cb(struct ssh *ssh, Channel *c) 1163 { 1164 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1165 struct sshbuf *in = NULL, *out = NULL; 1166 u_int type, rid, i; 1167 int r, ret = -1; 1168 1169 if ((out = sshbuf_new()) == NULL) 1170 fatal("%s: sshbuf_new", __func__); 1171 1172 /* Setup ctx and */ 1173 if (c->mux_ctx == NULL) { 1174 state = xcalloc(1, sizeof(*state)); 1175 c->mux_ctx = state; 1176 channel_register_cleanup(ssh, c->self, 1177 mux_master_control_cleanup_cb, 0); 1178 1179 /* Send hello */ 1180 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1181 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1182 fatal("%s: reply: %s", __func__, ssh_err(r)); 1183 /* no extensions */ 1184 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1185 fatal("%s: sshbuf_put_stringb: %s", 1186 __func__, ssh_err(r)); 1187 debug3("%s: channel %d: hello sent", __func__, c->self); 1188 ret = 0; 1189 goto out; 1190 } 1191 1192 /* Channel code ensures that we receive whole packets */ 1193 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1194 malf: 1195 error("%s: malformed message", __func__); 1196 goto out; 1197 } 1198 1199 if ((r = sshbuf_get_u32(in, &type)) != 0) 1200 goto malf; 1201 debug3("%s: channel %d packet type 0x%08x len %zu", 1202 __func__, c->self, type, sshbuf_len(in)); 1203 1204 if (type == MUX_MSG_HELLO) 1205 rid = 0; 1206 else { 1207 if (!state->hello_rcvd) { 1208 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1209 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1210 goto out; 1211 } 1212 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1213 goto malf; 1214 } 1215 1216 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1217 if (type == mux_master_handlers[i].type) { 1218 ret = mux_master_handlers[i].handler(ssh, rid, 1219 c, in, out); 1220 break; 1221 } 1222 } 1223 if (mux_master_handlers[i].handler == NULL) { 1224 error("%s: unsupported mux message 0x%08x", __func__, type); 1225 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1226 ret = 0; 1227 } 1228 /* Enqueue reply packet */ 1229 if (sshbuf_len(out) != 0) { 1230 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1231 fatal("%s: sshbuf_put_stringb: %s", 1232 __func__, ssh_err(r)); 1233 } 1234 out: 1235 sshbuf_free(in); 1236 sshbuf_free(out); 1237 return ret; 1238 } 1239 1240 void 1241 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1242 { 1243 struct sshbuf *m; 1244 Channel *mux_chan; 1245 int r; 1246 1247 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1248 exitval); 1249 1250 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1251 fatal("%s: channel %d missing mux channel %d", 1252 __func__, c->self, c->ctl_chan); 1253 1254 /* Append exit message packet to control socket output queue */ 1255 if ((m = sshbuf_new()) == NULL) 1256 fatal("%s: sshbuf_new", __func__); 1257 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1258 (r = sshbuf_put_u32(m, c->self)) != 0 || 1259 (r = sshbuf_put_u32(m, exitval)) != 0 || 1260 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1261 fatal("%s: reply: %s", __func__, ssh_err(r)); 1262 sshbuf_free(m); 1263 } 1264 1265 void 1266 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1267 { 1268 struct sshbuf *m; 1269 Channel *mux_chan; 1270 int r; 1271 1272 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1273 1274 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1275 fatal("%s: channel %d missing mux channel %d", 1276 __func__, c->self, c->ctl_chan); 1277 1278 /* Append exit message packet to control socket output queue */ 1279 if ((m = sshbuf_new()) == NULL) 1280 fatal("%s: sshbuf_new", __func__); 1281 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1282 (r = sshbuf_put_u32(m, c->self)) != 0 || 1283 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1284 fatal("%s: reply: %s", __func__, ssh_err(r)); 1285 sshbuf_free(m); 1286 } 1287 1288 /* Prepare a mux master to listen on a Unix domain socket. */ 1289 void 1290 muxserver_listen(struct ssh *ssh) 1291 { 1292 mode_t old_umask; 1293 char *orig_control_path = options.control_path; 1294 char rbuf[16+1]; 1295 u_int i, r; 1296 int oerrno; 1297 1298 if (options.control_path == NULL || 1299 options.control_master == SSHCTL_MASTER_NO) 1300 return; 1301 1302 debug("setting up multiplex master socket"); 1303 1304 /* 1305 * Use a temporary path before listen so we can pseudo-atomically 1306 * establish the listening socket in its final location to avoid 1307 * other processes racing in between bind() and listen() and hitting 1308 * an unready socket. 1309 */ 1310 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1311 r = arc4random_uniform(26+26+10); 1312 rbuf[i] = (r < 26) ? 'a' + r : 1313 (r < 26*2) ? 'A' + r - 26 : 1314 '0' + r - 26 - 26; 1315 } 1316 rbuf[sizeof(rbuf) - 1] = '\0'; 1317 options.control_path = NULL; 1318 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1319 debug3("%s: temporary control path %s", __func__, options.control_path); 1320 1321 old_umask = umask(0177); 1322 muxserver_sock = unix_listener(options.control_path, 64, 0); 1323 oerrno = errno; 1324 umask(old_umask); 1325 if (muxserver_sock < 0) { 1326 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1327 error("ControlSocket %s already exists, " 1328 "disabling multiplexing", options.control_path); 1329 disable_mux_master: 1330 if (muxserver_sock != -1) { 1331 close(muxserver_sock); 1332 muxserver_sock = -1; 1333 } 1334 free(orig_control_path); 1335 free(options.control_path); 1336 options.control_path = NULL; 1337 options.control_master = SSHCTL_MASTER_NO; 1338 return; 1339 } else { 1340 /* unix_listener() logs the error */ 1341 cleanup_exit(255); 1342 } 1343 } 1344 1345 /* Now atomically "move" the mux socket into position */ 1346 if (link(options.control_path, orig_control_path) != 0) { 1347 if (errno != EEXIST) { 1348 fatal("%s: link mux listener %s => %s: %s", __func__, 1349 options.control_path, orig_control_path, 1350 strerror(errno)); 1351 } 1352 error("ControlSocket %s already exists, disabling multiplexing", 1353 orig_control_path); 1354 unlink(options.control_path); 1355 goto disable_mux_master; 1356 } 1357 unlink(options.control_path); 1358 free(options.control_path); 1359 options.control_path = orig_control_path; 1360 1361 set_nonblock(muxserver_sock); 1362 1363 mux_listener_channel = channel_new(ssh, "mux listener", 1364 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1365 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1366 0, options.control_path, 1); 1367 mux_listener_channel->mux_rcb = mux_master_read_cb; 1368 debug3("%s: mux listener channel %d fd %d", __func__, 1369 mux_listener_channel->self, mux_listener_channel->sock); 1370 } 1371 1372 /* Callback on open confirmation in mux master for a mux client session. */ 1373 static void 1374 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1375 { 1376 struct mux_session_confirm_ctx *cctx = arg; 1377 const char *display; 1378 Channel *c, *cc; 1379 int i, r; 1380 struct sshbuf *reply; 1381 1382 if (cctx == NULL) 1383 fatal("%s: cctx == NULL", __func__); 1384 if ((c = channel_by_id(ssh, id)) == NULL) 1385 fatal("%s: no channel for id %d", __func__, id); 1386 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1387 fatal("%s: channel %d lacks control channel %d", __func__, 1388 id, c->ctl_chan); 1389 if ((reply = sshbuf_new()) == NULL) 1390 fatal("%s: sshbuf_new", __func__); 1391 1392 if (!success) { 1393 debug3("%s: sending failure reply", __func__); 1394 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1395 "Session open refused by peer"); 1396 goto done; 1397 } 1398 1399 display = getenv("DISPLAY"); 1400 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1401 char *proto, *data; 1402 1403 /* Get reasonable local authentication information. */ 1404 if (client_x11_get_proto(ssh, display, options.xauth_location, 1405 options.forward_x11_trusted, options.forward_x11_timeout, 1406 &proto, &data) == 0) { 1407 /* Request forwarding with authentication spoofing. */ 1408 debug("Requesting X11 forwarding with authentication " 1409 "spoofing."); 1410 x11_request_forwarding_with_spoofing(ssh, id, 1411 display, proto, data, 1); 1412 /* XXX exit_on_forward_failure */ 1413 client_expect_confirm(ssh, id, "X11 forwarding", 1414 CONFIRM_WARN); 1415 } 1416 } 1417 1418 if (cctx->want_agent_fwd && options.forward_agent) { 1419 debug("Requesting authentication agent forwarding."); 1420 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1421 packet_send(); 1422 } 1423 1424 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1425 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1426 1427 debug3("%s: sending success reply", __func__); 1428 /* prepare reply */ 1429 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1430 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1431 (r = sshbuf_put_u32(reply, c->self)) != 0) 1432 fatal("%s: reply: %s", __func__, ssh_err(r)); 1433 1434 done: 1435 /* Send reply */ 1436 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1437 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 1438 sshbuf_free(reply); 1439 1440 if (cc->mux_pause <= 0) 1441 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1442 cc->mux_pause = 0; /* start processing messages again */ 1443 c->open_confirm_ctx = NULL; 1444 sshbuf_free(cctx->cmd); 1445 free(cctx->term); 1446 if (cctx->env != NULL) { 1447 for (i = 0; cctx->env[i] != NULL; i++) 1448 free(cctx->env[i]); 1449 free(cctx->env); 1450 } 1451 free(cctx); 1452 } 1453 1454 /* ** Multiplexing client support */ 1455 1456 /* Exit signal handler */ 1457 static void 1458 control_client_sighandler(int signo) 1459 { 1460 muxclient_terminate = signo; 1461 } 1462 1463 /* 1464 * Relay signal handler - used to pass some signals from mux client to 1465 * mux master. 1466 */ 1467 static void 1468 control_client_sigrelay(int signo) 1469 { 1470 int save_errno = errno; 1471 1472 if (muxserver_pid > 1) 1473 kill(muxserver_pid, signo); 1474 1475 errno = save_errno; 1476 } 1477 1478 static int 1479 mux_client_read(int fd, struct sshbuf *b, size_t need) 1480 { 1481 size_t have; 1482 ssize_t len; 1483 u_char *p; 1484 struct pollfd pfd; 1485 int r; 1486 1487 pfd.fd = fd; 1488 pfd.events = POLLIN; 1489 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1490 fatal("%s: reserve: %s", __func__, ssh_err(r)); 1491 for (have = 0; have < need; ) { 1492 if (muxclient_terminate) { 1493 errno = EINTR; 1494 return -1; 1495 } 1496 len = read(fd, p + have, need - have); 1497 if (len < 0) { 1498 switch (errno) { 1499 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1500 case EWOULDBLOCK: 1501 #endif 1502 case EAGAIN: 1503 (void)poll(&pfd, 1, -1); 1504 /* FALLTHROUGH */ 1505 case EINTR: 1506 continue; 1507 default: 1508 return -1; 1509 } 1510 } 1511 if (len == 0) { 1512 errno = EPIPE; 1513 return -1; 1514 } 1515 have += (size_t)len; 1516 } 1517 return 0; 1518 } 1519 1520 static int 1521 mux_client_write_packet(int fd, struct sshbuf *m) 1522 { 1523 struct sshbuf *queue; 1524 u_int have, need; 1525 int r, oerrno, len; 1526 const u_char *ptr; 1527 struct pollfd pfd; 1528 1529 pfd.fd = fd; 1530 pfd.events = POLLOUT; 1531 if ((queue = sshbuf_new()) == NULL) 1532 fatal("%s: sshbuf_new", __func__); 1533 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1534 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 1535 1536 need = sshbuf_len(queue); 1537 ptr = sshbuf_ptr(queue); 1538 1539 for (have = 0; have < need; ) { 1540 if (muxclient_terminate) { 1541 sshbuf_free(queue); 1542 errno = EINTR; 1543 return -1; 1544 } 1545 len = write(fd, ptr + have, need - have); 1546 if (len < 0) { 1547 switch (errno) { 1548 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1549 case EWOULDBLOCK: 1550 #endif 1551 case EAGAIN: 1552 (void)poll(&pfd, 1, -1); 1553 /* FALLTHROUGH */ 1554 case EINTR: 1555 continue; 1556 default: 1557 oerrno = errno; 1558 sshbuf_free(queue); 1559 errno = oerrno; 1560 return -1; 1561 } 1562 } 1563 if (len == 0) { 1564 sshbuf_free(queue); 1565 errno = EPIPE; 1566 return -1; 1567 } 1568 have += (u_int)len; 1569 } 1570 sshbuf_free(queue); 1571 return 0; 1572 } 1573 1574 static int 1575 mux_client_read_packet(int fd, struct sshbuf *m) 1576 { 1577 struct sshbuf *queue; 1578 size_t need, have; 1579 const u_char *ptr; 1580 int r, oerrno; 1581 1582 if ((queue = sshbuf_new()) == NULL) 1583 fatal("%s: sshbuf_new", __func__); 1584 if (mux_client_read(fd, queue, 4) != 0) { 1585 if ((oerrno = errno) == EPIPE) 1586 debug3("%s: read header failed: %s", __func__, 1587 strerror(errno)); 1588 sshbuf_free(queue); 1589 errno = oerrno; 1590 return -1; 1591 } 1592 need = PEEK_U32(sshbuf_ptr(queue)); 1593 if (mux_client_read(fd, queue, need) != 0) { 1594 oerrno = errno; 1595 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1596 sshbuf_free(queue); 1597 errno = oerrno; 1598 return -1; 1599 } 1600 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1601 (r = sshbuf_put(m, ptr, have)) != 0) 1602 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1603 sshbuf_free(queue); 1604 return 0; 1605 } 1606 1607 static int 1608 mux_client_hello_exchange(int fd) 1609 { 1610 struct sshbuf *m; 1611 u_int type, ver; 1612 int r, ret = -1; 1613 1614 if ((m = sshbuf_new()) == NULL) 1615 fatal("%s: sshbuf_new", __func__); 1616 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1617 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1618 fatal("%s: hello: %s", __func__, ssh_err(r)); 1619 /* no extensions */ 1620 1621 if (mux_client_write_packet(fd, m) != 0) { 1622 debug("%s: write packet: %s", __func__, strerror(errno)); 1623 goto out; 1624 } 1625 1626 sshbuf_reset(m); 1627 1628 /* Read their HELLO */ 1629 if (mux_client_read_packet(fd, m) != 0) { 1630 debug("%s: read packet failed", __func__); 1631 goto out; 1632 } 1633 1634 if ((r = sshbuf_get_u32(m, &type)) != 0) 1635 fatal("%s: decode type: %s", __func__, ssh_err(r)); 1636 if (type != MUX_MSG_HELLO) { 1637 error("%s: expected HELLO (%u) received %u", 1638 __func__, MUX_MSG_HELLO, type); 1639 goto out; 1640 } 1641 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1642 fatal("%s: decode version: %s", __func__, ssh_err(r)); 1643 if (ver != SSHMUX_VER) { 1644 error("Unsupported multiplexing protocol version %d " 1645 "(expected %d)", ver, SSHMUX_VER); 1646 goto out; 1647 } 1648 debug2("%s: master version %u", __func__, ver); 1649 /* No extensions are presently defined */ 1650 while (sshbuf_len(m) > 0) { 1651 char *name = NULL; 1652 1653 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1654 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1655 error("%s: malformed extension: %s", 1656 __func__, ssh_err(r)); 1657 goto out; 1658 } 1659 debug2("Unrecognised master extension \"%s\"", name); 1660 free(name); 1661 } 1662 /* success */ 1663 ret = 0; 1664 out: 1665 sshbuf_free(m); 1666 return ret; 1667 } 1668 1669 static u_int 1670 mux_client_request_alive(int fd) 1671 { 1672 struct sshbuf *m; 1673 char *e; 1674 u_int pid, type, rid; 1675 int r; 1676 1677 debug3("%s: entering", __func__); 1678 1679 if ((m = sshbuf_new()) == NULL) 1680 fatal("%s: sshbuf_new", __func__); 1681 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1682 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1683 fatal("%s: request: %s", __func__, ssh_err(r)); 1684 1685 if (mux_client_write_packet(fd, m) != 0) 1686 fatal("%s: write packet: %s", __func__, strerror(errno)); 1687 1688 sshbuf_reset(m); 1689 1690 /* Read their reply */ 1691 if (mux_client_read_packet(fd, m) != 0) { 1692 sshbuf_free(m); 1693 return 0; 1694 } 1695 1696 if ((r = sshbuf_get_u32(m, &type)) != 0) 1697 fatal("%s: decode type: %s", __func__, ssh_err(r)); 1698 if (type != MUX_S_ALIVE) { 1699 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1700 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1701 fatal("%s: master returned error: %s", __func__, e); 1702 } 1703 1704 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1705 fatal("%s: decode remote ID: %s", __func__, ssh_err(r)); 1706 if (rid != muxclient_request_id) 1707 fatal("%s: out of sequence reply: my id %u theirs %u", 1708 __func__, muxclient_request_id, rid); 1709 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1710 fatal("%s: decode PID: %s", __func__, ssh_err(r)); 1711 sshbuf_free(m); 1712 1713 debug3("%s: done pid = %u", __func__, pid); 1714 1715 muxclient_request_id++; 1716 1717 return pid; 1718 } 1719 1720 static void 1721 mux_client_request_terminate(int fd) 1722 { 1723 struct sshbuf *m; 1724 char *e; 1725 u_int type, rid; 1726 int r; 1727 1728 debug3("%s: entering", __func__); 1729 1730 if ((m = sshbuf_new()) == NULL) 1731 fatal("%s: sshbuf_new", __func__); 1732 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1733 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1734 fatal("%s: request: %s", __func__, ssh_err(r)); 1735 1736 if (mux_client_write_packet(fd, m) != 0) 1737 fatal("%s: write packet: %s", __func__, strerror(errno)); 1738 1739 sshbuf_reset(m); 1740 1741 /* Read their reply */ 1742 if (mux_client_read_packet(fd, m) != 0) { 1743 /* Remote end exited already */ 1744 if (errno == EPIPE) { 1745 sshbuf_free(m); 1746 return; 1747 } 1748 fatal("%s: read from master failed: %s", 1749 __func__, strerror(errno)); 1750 } 1751 1752 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1753 (r = sshbuf_get_u32(m, &rid)) != 0) 1754 fatal("%s: decode: %s", __func__, ssh_err(r)); 1755 if (rid != muxclient_request_id) 1756 fatal("%s: out of sequence reply: my id %u theirs %u", 1757 __func__, muxclient_request_id, rid); 1758 switch (type) { 1759 case MUX_S_OK: 1760 break; 1761 case MUX_S_PERMISSION_DENIED: 1762 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1763 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1764 fatal("Master refused termination request: %s", e); 1765 case MUX_S_FAILURE: 1766 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1767 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1768 fatal("%s: termination request failed: %s", __func__, e); 1769 default: 1770 fatal("%s: unexpected response from master 0x%08x", 1771 __func__, type); 1772 } 1773 sshbuf_free(m); 1774 muxclient_request_id++; 1775 } 1776 1777 static int 1778 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1779 { 1780 struct sshbuf *m; 1781 char *e, *fwd_desc; 1782 const char *lhost, *chost; 1783 u_int type, rid; 1784 int r; 1785 1786 fwd_desc = format_forward(ftype, fwd); 1787 debug("Requesting %s %s", 1788 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1789 free(fwd_desc); 1790 1791 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1792 if (fwd->listen_path != NULL) 1793 lhost = fwd->listen_path; 1794 else if (fwd->listen_host == NULL) 1795 lhost = ""; 1796 else if (*fwd->listen_host == '\0') 1797 lhost = "*"; 1798 else 1799 lhost = fwd->listen_host; 1800 1801 if (fwd->connect_path != NULL) 1802 chost = fwd->connect_path; 1803 else if (fwd->connect_host == NULL) 1804 chost = ""; 1805 else 1806 chost = fwd->connect_host; 1807 1808 if ((m = sshbuf_new()) == NULL) 1809 fatal("%s: sshbuf_new", __func__); 1810 if ((r = sshbuf_put_u32(m, type)) != 0 || 1811 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1812 (r = sshbuf_put_u32(m, ftype)) != 0 || 1813 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1814 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1815 (r = sshbuf_put_cstring(m, chost)) != 0 || 1816 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1817 fatal("%s: request: %s", __func__, ssh_err(r)); 1818 1819 if (mux_client_write_packet(fd, m) != 0) 1820 fatal("%s: write packet: %s", __func__, strerror(errno)); 1821 1822 sshbuf_reset(m); 1823 1824 /* Read their reply */ 1825 if (mux_client_read_packet(fd, m) != 0) { 1826 sshbuf_free(m); 1827 return -1; 1828 } 1829 1830 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1831 (r = sshbuf_get_u32(m, &rid)) != 0) 1832 fatal("%s: decode: %s", __func__, ssh_err(r)); 1833 if (rid != muxclient_request_id) 1834 fatal("%s: out of sequence reply: my id %u theirs %u", 1835 __func__, muxclient_request_id, rid); 1836 1837 switch (type) { 1838 case MUX_S_OK: 1839 break; 1840 case MUX_S_REMOTE_PORT: 1841 if (cancel_flag) 1842 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1843 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1844 fatal("%s: decode port: %s", __func__, ssh_err(r)); 1845 verbose("Allocated port %u for remote forward to %s:%d", 1846 fwd->allocated_port, 1847 fwd->connect_host ? fwd->connect_host : "", 1848 fwd->connect_port); 1849 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1850 fprintf(stdout, "%i\n", fwd->allocated_port); 1851 break; 1852 case MUX_S_PERMISSION_DENIED: 1853 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1854 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1855 sshbuf_free(m); 1856 error("Master refused forwarding request: %s", e); 1857 return -1; 1858 case MUX_S_FAILURE: 1859 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1860 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1861 sshbuf_free(m); 1862 error("%s: forwarding request failed: %s", __func__, e); 1863 return -1; 1864 default: 1865 fatal("%s: unexpected response from master 0x%08x", 1866 __func__, type); 1867 } 1868 sshbuf_free(m); 1869 1870 muxclient_request_id++; 1871 return 0; 1872 } 1873 1874 static int 1875 mux_client_forwards(int fd, int cancel_flag) 1876 { 1877 int i, ret = 0; 1878 1879 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1880 cancel_flag ? "cancel" : "request", 1881 options.num_local_forwards, options.num_remote_forwards); 1882 1883 /* XXX ExitOnForwardingFailure */ 1884 for (i = 0; i < options.num_local_forwards; i++) { 1885 if (mux_client_forward(fd, cancel_flag, 1886 options.local_forwards[i].connect_port == 0 ? 1887 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1888 options.local_forwards + i) != 0) 1889 ret = -1; 1890 } 1891 for (i = 0; i < options.num_remote_forwards; i++) { 1892 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1893 options.remote_forwards + i) != 0) 1894 ret = -1; 1895 } 1896 return ret; 1897 } 1898 1899 static int 1900 mux_client_request_session(int fd) 1901 { 1902 struct sshbuf *m; 1903 char *e; 1904 const char *term; 1905 u_int echar, rid, sid, esid, exitval, type, exitval_seen; 1906 extern char **environ; 1907 int r, i, devnull, rawmode; 1908 1909 debug3("%s: entering", __func__); 1910 1911 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1912 error("%s: master alive request failed", __func__); 1913 return -1; 1914 } 1915 1916 signal(SIGPIPE, SIG_IGN); 1917 1918 if (stdin_null_flag) { 1919 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1920 fatal("open(/dev/null): %s", strerror(errno)); 1921 if (dup2(devnull, STDIN_FILENO) == -1) 1922 fatal("dup2: %s", strerror(errno)); 1923 if (devnull > STDERR_FILENO) 1924 close(devnull); 1925 } 1926 1927 if ((term = getenv("TERM")) == NULL) 1928 term = ""; 1929 echar = 0xffffffff; 1930 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1931 echar = (u_int)options.escape_char; 1932 1933 if ((m = sshbuf_new()) == NULL) 1934 fatal("%s: sshbuf_new", __func__); 1935 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1936 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1937 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1938 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1939 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1940 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1941 (r = sshbuf_put_u32(m, subsystem_flag)) != 0 || 1942 (r = sshbuf_put_u32(m, echar)) != 0 || 1943 (r = sshbuf_put_cstring(m, term)) != 0 || 1944 (r = sshbuf_put_stringb(m, command)) != 0) 1945 fatal("%s: request: %s", __func__, ssh_err(r)); 1946 1947 /* Pass environment */ 1948 if (options.num_send_env > 0 && environ != NULL) { 1949 for (i = 0; environ[i] != NULL; i++) { 1950 if (!env_permitted(environ[i])) 1951 continue; 1952 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1953 fatal("%s: request: %s", __func__, ssh_err(r)); 1954 } 1955 } 1956 for (i = 0; i < options.num_setenv; i++) { 1957 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1958 fatal("%s: request: %s", __func__, ssh_err(r)); 1959 } 1960 1961 if (mux_client_write_packet(fd, m) != 0) 1962 fatal("%s: write packet: %s", __func__, strerror(errno)); 1963 1964 /* Send the stdio file descriptors */ 1965 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1966 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1967 mm_send_fd(fd, STDERR_FILENO) == -1) 1968 fatal("%s: send fds failed", __func__); 1969 1970 debug3("%s: session request sent", __func__); 1971 1972 /* Read their reply */ 1973 sshbuf_reset(m); 1974 if (mux_client_read_packet(fd, m) != 0) { 1975 error("%s: read from master failed: %s", 1976 __func__, strerror(errno)); 1977 sshbuf_free(m); 1978 return -1; 1979 } 1980 1981 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1982 (r = sshbuf_get_u32(m, &rid)) != 0) 1983 fatal("%s: decode: %s", __func__, ssh_err(r)); 1984 if (rid != muxclient_request_id) 1985 fatal("%s: out of sequence reply: my id %u theirs %u", 1986 __func__, muxclient_request_id, rid); 1987 1988 switch (type) { 1989 case MUX_S_SESSION_OPENED: 1990 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1991 fatal("%s: decode ID: %s", __func__, ssh_err(r)); 1992 break; 1993 case MUX_S_PERMISSION_DENIED: 1994 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1995 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1996 error("Master refused session request: %s", e); 1997 sshbuf_free(m); 1998 return -1; 1999 case MUX_S_FAILURE: 2000 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2001 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2002 error("%s: session request failed: %s", __func__, e); 2003 sshbuf_free(m); 2004 return -1; 2005 default: 2006 sshbuf_free(m); 2007 error("%s: unexpected response from master 0x%08x", 2008 __func__, type); 2009 return -1; 2010 } 2011 muxclient_request_id++; 2012 2013 if (pledge("stdio proc tty", NULL) == -1) 2014 fatal("%s pledge(): %s", __func__, strerror(errno)); 2015 platform_pledge_mux(); 2016 2017 signal(SIGHUP, control_client_sighandler); 2018 signal(SIGINT, control_client_sighandler); 2019 signal(SIGTERM, control_client_sighandler); 2020 signal(SIGWINCH, control_client_sigrelay); 2021 2022 rawmode = tty_flag; 2023 if (tty_flag) 2024 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2025 2026 /* 2027 * Stick around until the controlee closes the client_fd. 2028 * Before it does, it is expected to write an exit message. 2029 * This process must read the value and wait for the closure of 2030 * the client_fd; if this one closes early, the multiplex master will 2031 * terminate early too (possibly losing data). 2032 */ 2033 for (exitval = 255, exitval_seen = 0;;) { 2034 sshbuf_reset(m); 2035 if (mux_client_read_packet(fd, m) != 0) 2036 break; 2037 if ((r = sshbuf_get_u32(m, &type)) != 0) 2038 fatal("%s: decode type: %s", __func__, ssh_err(r)); 2039 switch (type) { 2040 case MUX_S_TTY_ALLOC_FAIL: 2041 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2042 fatal("%s: decode ID: %s", 2043 __func__, ssh_err(r)); 2044 if (esid != sid) 2045 fatal("%s: tty alloc fail on unknown session: " 2046 "my id %u theirs %u", 2047 __func__, sid, esid); 2048 leave_raw_mode(options.request_tty == 2049 REQUEST_TTY_FORCE); 2050 rawmode = 0; 2051 continue; 2052 case MUX_S_EXIT_MESSAGE: 2053 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2054 fatal("%s: decode ID: %s", 2055 __func__, ssh_err(r)); 2056 if (esid != sid) 2057 fatal("%s: exit on unknown session: " 2058 "my id %u theirs %u", 2059 __func__, sid, esid); 2060 if (exitval_seen) 2061 fatal("%s: exitval sent twice", __func__); 2062 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2063 fatal("%s: decode exit value: %s", 2064 __func__, ssh_err(r)); 2065 exitval_seen = 1; 2066 continue; 2067 default: 2068 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2069 fatal("%s: decode error: %s", 2070 __func__, ssh_err(r)); 2071 fatal("%s: master returned error: %s", __func__, e); 2072 } 2073 } 2074 2075 close(fd); 2076 if (rawmode) 2077 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2078 2079 if (muxclient_terminate) { 2080 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2081 exitval = 255; 2082 } else if (!exitval_seen) { 2083 debug2("Control master terminated unexpectedly"); 2084 exitval = 255; 2085 } else 2086 debug2("Received exit status from master %d", exitval); 2087 2088 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 2089 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2090 2091 exit(exitval); 2092 } 2093 2094 static int 2095 mux_client_proxy(int fd) 2096 { 2097 struct sshbuf *m; 2098 char *e; 2099 u_int type, rid; 2100 int r; 2101 2102 if ((m = sshbuf_new()) == NULL) 2103 fatal("%s: sshbuf_new", __func__); 2104 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2105 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2106 fatal("%s: request: %s", __func__, ssh_err(r)); 2107 if (mux_client_write_packet(fd, m) != 0) 2108 fatal("%s: write packet: %s", __func__, strerror(errno)); 2109 2110 sshbuf_reset(m); 2111 2112 /* Read their reply */ 2113 if (mux_client_read_packet(fd, m) != 0) { 2114 sshbuf_free(m); 2115 return 0; 2116 } 2117 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2118 (r = sshbuf_get_u32(m, &rid)) != 0) 2119 fatal("%s: decode: %s", __func__, ssh_err(r)); 2120 if (rid != muxclient_request_id) 2121 fatal("%s: out of sequence reply: my id %u theirs %u", 2122 __func__, muxclient_request_id, rid); 2123 if (type != MUX_S_PROXY) { 2124 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2125 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2126 fatal("%s: master returned error: %s", __func__, e); 2127 } 2128 sshbuf_free(m); 2129 2130 debug3("%s: done", __func__); 2131 muxclient_request_id++; 2132 return 0; 2133 } 2134 2135 static int 2136 mux_client_request_stdio_fwd(int fd) 2137 { 2138 struct sshbuf *m; 2139 char *e; 2140 u_int type, rid, sid; 2141 int r, devnull; 2142 2143 debug3("%s: entering", __func__); 2144 2145 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2146 error("%s: master alive request failed", __func__); 2147 return -1; 2148 } 2149 2150 signal(SIGPIPE, SIG_IGN); 2151 2152 if (stdin_null_flag) { 2153 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 2154 fatal("open(/dev/null): %s", strerror(errno)); 2155 if (dup2(devnull, STDIN_FILENO) == -1) 2156 fatal("dup2: %s", strerror(errno)); 2157 if (devnull > STDERR_FILENO) 2158 close(devnull); 2159 } 2160 2161 if ((m = sshbuf_new()) == NULL) 2162 fatal("%s: sshbuf_new", __func__); 2163 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2164 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2165 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2166 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2167 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2168 fatal("%s: request: %s", __func__, ssh_err(r)); 2169 2170 if (mux_client_write_packet(fd, m) != 0) 2171 fatal("%s: write packet: %s", __func__, strerror(errno)); 2172 2173 /* Send the stdio file descriptors */ 2174 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2175 mm_send_fd(fd, STDOUT_FILENO) == -1) 2176 fatal("%s: send fds failed", __func__); 2177 2178 if (pledge("stdio proc tty", NULL) == -1) 2179 fatal("%s pledge(): %s", __func__, strerror(errno)); 2180 platform_pledge_mux(); 2181 2182 debug3("%s: stdio forward request sent", __func__); 2183 2184 /* Read their reply */ 2185 sshbuf_reset(m); 2186 2187 if (mux_client_read_packet(fd, m) != 0) { 2188 error("%s: read from master failed: %s", 2189 __func__, strerror(errno)); 2190 sshbuf_free(m); 2191 return -1; 2192 } 2193 2194 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2195 (r = sshbuf_get_u32(m, &rid)) != 0) 2196 fatal("%s: decode: %s", __func__, ssh_err(r)); 2197 if (rid != muxclient_request_id) 2198 fatal("%s: out of sequence reply: my id %u theirs %u", 2199 __func__, muxclient_request_id, rid); 2200 switch (type) { 2201 case MUX_S_SESSION_OPENED: 2202 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2203 fatal("%s: decode ID: %s", __func__, ssh_err(r)); 2204 debug("%s: master session id: %u", __func__, sid); 2205 break; 2206 case MUX_S_PERMISSION_DENIED: 2207 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2208 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2209 sshbuf_free(m); 2210 fatal("Master refused stdio forwarding request: %s", e); 2211 case MUX_S_FAILURE: 2212 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2213 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2214 sshbuf_free(m); 2215 fatal("Stdio forwarding request failed: %s", e); 2216 default: 2217 sshbuf_free(m); 2218 error("%s: unexpected response from master 0x%08x", 2219 __func__, type); 2220 return -1; 2221 } 2222 muxclient_request_id++; 2223 2224 signal(SIGHUP, control_client_sighandler); 2225 signal(SIGINT, control_client_sighandler); 2226 signal(SIGTERM, control_client_sighandler); 2227 signal(SIGWINCH, control_client_sigrelay); 2228 2229 /* 2230 * Stick around until the controlee closes the client_fd. 2231 */ 2232 sshbuf_reset(m); 2233 if (mux_client_read_packet(fd, m) != 0) { 2234 if (errno == EPIPE || 2235 (errno == EINTR && muxclient_terminate != 0)) 2236 return 0; 2237 fatal("%s: mux_client_read_packet: %s", 2238 __func__, strerror(errno)); 2239 } 2240 fatal("%s: master returned unexpected message %u", __func__, type); 2241 } 2242 2243 static void 2244 mux_client_request_stop_listening(int fd) 2245 { 2246 struct sshbuf *m; 2247 char *e; 2248 u_int type, rid; 2249 int r; 2250 2251 debug3("%s: entering", __func__); 2252 2253 if ((m = sshbuf_new()) == NULL) 2254 fatal("%s: sshbuf_new", __func__); 2255 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2256 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2257 fatal("%s: request: %s", __func__, ssh_err(r)); 2258 2259 if (mux_client_write_packet(fd, m) != 0) 2260 fatal("%s: write packet: %s", __func__, strerror(errno)); 2261 2262 sshbuf_reset(m); 2263 2264 /* Read their reply */ 2265 if (mux_client_read_packet(fd, m) != 0) 2266 fatal("%s: read from master failed: %s", 2267 __func__, strerror(errno)); 2268 2269 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2270 (r = sshbuf_get_u32(m, &rid)) != 0) 2271 fatal("%s: decode: %s", __func__, ssh_err(r)); 2272 if (rid != muxclient_request_id) 2273 fatal("%s: out of sequence reply: my id %u theirs %u", 2274 __func__, muxclient_request_id, rid); 2275 2276 switch (type) { 2277 case MUX_S_OK: 2278 break; 2279 case MUX_S_PERMISSION_DENIED: 2280 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2281 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2282 fatal("Master refused stop listening request: %s", e); 2283 case MUX_S_FAILURE: 2284 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2285 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2286 fatal("%s: stop listening request failed: %s", __func__, e); 2287 default: 2288 fatal("%s: unexpected response from master 0x%08x", 2289 __func__, type); 2290 } 2291 sshbuf_free(m); 2292 muxclient_request_id++; 2293 } 2294 2295 /* Multiplex client main loop. */ 2296 int 2297 muxclient(const char *path) 2298 { 2299 struct sockaddr_un addr; 2300 int sock; 2301 u_int pid; 2302 2303 if (muxclient_command == 0) { 2304 if (options.stdio_forward_host != NULL) 2305 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2306 else 2307 muxclient_command = SSHMUX_COMMAND_OPEN; 2308 } 2309 2310 switch (options.control_master) { 2311 case SSHCTL_MASTER_AUTO: 2312 case SSHCTL_MASTER_AUTO_ASK: 2313 debug("auto-mux: Trying existing master"); 2314 /* FALLTHROUGH */ 2315 case SSHCTL_MASTER_NO: 2316 break; 2317 default: 2318 return -1; 2319 } 2320 2321 memset(&addr, '\0', sizeof(addr)); 2322 addr.sun_family = AF_UNIX; 2323 2324 if (strlcpy(addr.sun_path, path, 2325 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2326 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2327 (unsigned int)sizeof(addr.sun_path)); 2328 2329 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2330 fatal("%s socket(): %s", __func__, strerror(errno)); 2331 2332 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2333 switch (muxclient_command) { 2334 case SSHMUX_COMMAND_OPEN: 2335 case SSHMUX_COMMAND_STDIO_FWD: 2336 break; 2337 default: 2338 fatal("Control socket connect(%.100s): %s", path, 2339 strerror(errno)); 2340 } 2341 if (errno == ECONNREFUSED && 2342 options.control_master != SSHCTL_MASTER_NO) { 2343 debug("Stale control socket %.100s, unlinking", path); 2344 unlink(path); 2345 } else if (errno == ENOENT) { 2346 debug("Control socket \"%.100s\" does not exist", path); 2347 } else { 2348 error("Control socket connect(%.100s): %s", path, 2349 strerror(errno)); 2350 } 2351 close(sock); 2352 return -1; 2353 } 2354 set_nonblock(sock); 2355 2356 if (mux_client_hello_exchange(sock) != 0) { 2357 error("%s: master hello exchange failed", __func__); 2358 close(sock); 2359 return -1; 2360 } 2361 2362 switch (muxclient_command) { 2363 case SSHMUX_COMMAND_ALIVE_CHECK: 2364 if ((pid = mux_client_request_alive(sock)) == 0) 2365 fatal("%s: master alive check failed", __func__); 2366 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2367 exit(0); 2368 case SSHMUX_COMMAND_TERMINATE: 2369 mux_client_request_terminate(sock); 2370 if (options.log_level != SYSLOG_LEVEL_QUIET) 2371 fprintf(stderr, "Exit request sent.\r\n"); 2372 exit(0); 2373 case SSHMUX_COMMAND_FORWARD: 2374 if (mux_client_forwards(sock, 0) != 0) 2375 fatal("%s: master forward request failed", __func__); 2376 exit(0); 2377 case SSHMUX_COMMAND_OPEN: 2378 if (mux_client_forwards(sock, 0) != 0) { 2379 error("%s: master forward request failed", __func__); 2380 return -1; 2381 } 2382 mux_client_request_session(sock); 2383 return -1; 2384 case SSHMUX_COMMAND_STDIO_FWD: 2385 mux_client_request_stdio_fwd(sock); 2386 exit(0); 2387 case SSHMUX_COMMAND_STOP: 2388 mux_client_request_stop_listening(sock); 2389 if (options.log_level != SYSLOG_LEVEL_QUIET) 2390 fprintf(stderr, "Stop listening request sent.\r\n"); 2391 exit(0); 2392 case SSHMUX_COMMAND_CANCEL_FWD: 2393 if (mux_client_forwards(sock, 1) != 0) 2394 error("%s: master cancel forward request failed", 2395 __func__); 2396 exit(0); 2397 case SSHMUX_COMMAND_PROXY: 2398 mux_client_proxy(sock); 2399 return (sock); 2400 default: 2401 fatal("unrecognised muxclient_command %d", muxclient_command); 2402 } 2403 } 2404