1 /* $OpenBSD: mux.c,v 1.86 2020/10/29 02:52:43 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 #include <sys/types.h> 21 #include <sys/queue.h> 22 #include <sys/stat.h> 23 #include <sys/socket.h> 24 #include <sys/un.h> 25 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <poll.h> 29 #include <signal.h> 30 #include <stdarg.h> 31 #include <stddef.h> 32 #include <stdlib.h> 33 #include <stdio.h> 34 #include <string.h> 35 #include <unistd.h> 36 #include <util.h> 37 #include <paths.h> 38 39 #include "atomicio.h" 40 #include "xmalloc.h" 41 #include "log.h" 42 #include "ssh.h" 43 #include "ssh2.h" 44 #include "pathnames.h" 45 #include "misc.h" 46 #include "match.h" 47 #include "sshbuf.h" 48 #include "channels.h" 49 #include "msg.h" 50 #include "packet.h" 51 #include "monitor_fdpass.h" 52 #include "sshpty.h" 53 #include "sshkey.h" 54 #include "readconf.h" 55 #include "clientloop.h" 56 #include "ssherr.h" 57 58 /* from ssh.c */ 59 extern int tty_flag; 60 extern Options options; 61 extern int stdin_null_flag; 62 extern char *host; 63 extern int subsystem_flag; 64 extern struct sshbuf *command; 65 extern volatile sig_atomic_t quit_pending; 66 67 /* Context for session open confirmation callback */ 68 struct mux_session_confirm_ctx { 69 u_int want_tty; 70 u_int want_subsys; 71 u_int want_x_fwd; 72 u_int want_agent_fwd; 73 struct sshbuf *cmd; 74 char *term; 75 struct termios tio; 76 char **env; 77 u_int rid; 78 }; 79 80 /* Context for stdio fwd open confirmation callback */ 81 struct mux_stdio_confirm_ctx { 82 u_int rid; 83 }; 84 85 /* Context for global channel callback */ 86 struct mux_channel_confirm_ctx { 87 u_int cid; /* channel id */ 88 u_int rid; /* request id */ 89 int fid; /* forward id */ 90 }; 91 92 /* fd to control socket */ 93 int muxserver_sock = -1; 94 95 /* client request id */ 96 u_int muxclient_request_id = 0; 97 98 /* Multiplexing control command */ 99 u_int muxclient_command = 0; 100 101 /* Set when signalled. */ 102 static volatile sig_atomic_t muxclient_terminate = 0; 103 104 /* PID of multiplex server */ 105 static u_int muxserver_pid = 0; 106 107 static Channel *mux_listener_channel = NULL; 108 109 struct mux_master_state { 110 int hello_rcvd; 111 }; 112 113 /* mux protocol messages */ 114 #define MUX_MSG_HELLO 0x00000001 115 #define MUX_C_NEW_SESSION 0x10000002 116 #define MUX_C_ALIVE_CHECK 0x10000004 117 #define MUX_C_TERMINATE 0x10000005 118 #define MUX_C_OPEN_FWD 0x10000006 119 #define MUX_C_CLOSE_FWD 0x10000007 120 #define MUX_C_NEW_STDIO_FWD 0x10000008 121 #define MUX_C_STOP_LISTENING 0x10000009 122 #define MUX_C_PROXY 0x1000000f 123 #define MUX_S_OK 0x80000001 124 #define MUX_S_PERMISSION_DENIED 0x80000002 125 #define MUX_S_FAILURE 0x80000003 126 #define MUX_S_EXIT_MESSAGE 0x80000004 127 #define MUX_S_ALIVE 0x80000005 128 #define MUX_S_SESSION_OPENED 0x80000006 129 #define MUX_S_REMOTE_PORT 0x80000007 130 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 131 #define MUX_S_PROXY 0x8000000f 132 133 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 134 #define MUX_FWD_LOCAL 1 135 #define MUX_FWD_REMOTE 2 136 #define MUX_FWD_DYNAMIC 3 137 138 static void mux_session_confirm(struct ssh *, int, int, void *); 139 static void mux_stdio_confirm(struct ssh *, int, int, void *); 140 141 static int mux_master_process_hello(struct ssh *, u_int, 142 Channel *, struct sshbuf *, struct sshbuf *); 143 static int mux_master_process_new_session(struct ssh *, u_int, 144 Channel *, struct sshbuf *, struct sshbuf *); 145 static int mux_master_process_alive_check(struct ssh *, u_int, 146 Channel *, struct sshbuf *, struct sshbuf *); 147 static int mux_master_process_terminate(struct ssh *, u_int, 148 Channel *, struct sshbuf *, struct sshbuf *); 149 static int mux_master_process_open_fwd(struct ssh *, u_int, 150 Channel *, struct sshbuf *, struct sshbuf *); 151 static int mux_master_process_close_fwd(struct ssh *, u_int, 152 Channel *, struct sshbuf *, struct sshbuf *); 153 static int mux_master_process_stdio_fwd(struct ssh *, u_int, 154 Channel *, struct sshbuf *, struct sshbuf *); 155 static int mux_master_process_stop_listening(struct ssh *, u_int, 156 Channel *, struct sshbuf *, struct sshbuf *); 157 static int mux_master_process_proxy(struct ssh *, u_int, 158 Channel *, struct sshbuf *, struct sshbuf *); 159 160 static const struct { 161 u_int type; 162 int (*handler)(struct ssh *, u_int, Channel *, 163 struct sshbuf *, struct sshbuf *); 164 } mux_master_handlers[] = { 165 { MUX_MSG_HELLO, mux_master_process_hello }, 166 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 167 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 168 { MUX_C_TERMINATE, mux_master_process_terminate }, 169 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 170 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 171 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 172 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 173 { MUX_C_PROXY, mux_master_process_proxy }, 174 { 0, NULL } 175 }; 176 177 /* Cleanup callback fired on closure of mux client _session_ channel */ 178 /* ARGSUSED */ 179 static void 180 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused) 181 { 182 Channel *cc, *c = channel_by_id(ssh, cid); 183 184 debug3_f("entering for channel %d", cid); 185 if (c == NULL) 186 fatal_f("channel_by_id(%i) == NULL", cid); 187 if (c->ctl_chan != -1) { 188 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 189 fatal_f("channel %d missing control channel %d", 190 c->self, c->ctl_chan); 191 c->ctl_chan = -1; 192 cc->remote_id = 0; 193 cc->have_remote_id = 0; 194 chan_rcvd_oclose(ssh, cc); 195 } 196 channel_cancel_cleanup(ssh, c->self); 197 } 198 199 /* Cleanup callback fired on closure of mux client _control_ channel */ 200 /* ARGSUSED */ 201 static void 202 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused) 203 { 204 Channel *sc, *c = channel_by_id(ssh, cid); 205 206 debug3_f("entering for channel %d", cid); 207 if (c == NULL) 208 fatal_f("channel_by_id(%i) == NULL", cid); 209 if (c->have_remote_id) { 210 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 211 fatal_f("channel %d missing session channel %u", 212 c->self, c->remote_id); 213 c->remote_id = 0; 214 c->have_remote_id = 0; 215 sc->ctl_chan = -1; 216 if (sc->type != SSH_CHANNEL_OPEN && 217 sc->type != SSH_CHANNEL_OPENING) { 218 debug2_f("channel %d: not open", sc->self); 219 chan_mark_dead(ssh, sc); 220 } else { 221 if (sc->istate == CHAN_INPUT_OPEN) 222 chan_read_failed(ssh, sc); 223 if (sc->ostate == CHAN_OUTPUT_OPEN) 224 chan_write_failed(ssh, sc); 225 } 226 } 227 channel_cancel_cleanup(ssh, c->self); 228 } 229 230 /* Check mux client environment variables before passing them to mux master. */ 231 static int 232 env_permitted(char *env) 233 { 234 int i, ret; 235 char name[1024], *cp; 236 237 if ((cp = strchr(env, '=')) == NULL || cp == env) 238 return 0; 239 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 240 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 241 error_f("name '%.100s...' too long", env); 242 return 0; 243 } 244 245 for (i = 0; i < options.num_send_env; i++) 246 if (match_pattern(name, options.send_env[i])) 247 return 1; 248 249 return 0; 250 } 251 252 /* Mux master protocol message handlers */ 253 254 static int 255 mux_master_process_hello(struct ssh *ssh, u_int rid, 256 Channel *c, struct sshbuf *m, struct sshbuf *reply) 257 { 258 u_int ver; 259 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 260 int r; 261 262 if (state == NULL) 263 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 264 if (state->hello_rcvd) { 265 error_f("HELLO received twice"); 266 return -1; 267 } 268 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 269 error_fr(r, "parse"); 270 return -1; 271 } 272 if (ver != SSHMUX_VER) { 273 error_f("unsupported multiplexing protocol version %u " 274 "(expected %u)", ver, SSHMUX_VER); 275 return -1; 276 } 277 debug2_f("channel %d client version %u", c->self, ver); 278 279 /* No extensions are presently defined */ 280 while (sshbuf_len(m) > 0) { 281 char *name = NULL; 282 size_t value_len = 0; 283 284 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 285 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 286 error_fr(r, "parse extension"); 287 return -1; 288 } 289 debug2_f("Unrecognised extension \"%s\" length %zu", 290 name, value_len); 291 free(name); 292 } 293 state->hello_rcvd = 1; 294 return 0; 295 } 296 297 /* Enqueue a "ok" response to the reply buffer */ 298 static void 299 reply_ok(struct sshbuf *reply, u_int rid) 300 { 301 int r; 302 303 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 304 (r = sshbuf_put_u32(reply, rid)) != 0) 305 fatal_fr(r, "reply"); 306 } 307 308 /* Enqueue an error response to the reply buffer */ 309 static void 310 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 311 { 312 int r; 313 314 if ((r = sshbuf_put_u32(reply, type)) != 0 || 315 (r = sshbuf_put_u32(reply, rid)) != 0 || 316 (r = sshbuf_put_cstring(reply, msg)) != 0) 317 fatal_fr(r, "reply"); 318 } 319 320 static int 321 mux_master_process_new_session(struct ssh *ssh, u_int rid, 322 Channel *c, struct sshbuf *m, struct sshbuf *reply) 323 { 324 Channel *nc; 325 struct mux_session_confirm_ctx *cctx; 326 char *cmd, *cp; 327 u_int i, j, env_len, escape_char, window, packetmax; 328 int r, new_fd[3]; 329 330 /* Reply for SSHMUX_COMMAND_OPEN */ 331 cctx = xcalloc(1, sizeof(*cctx)); 332 cctx->term = NULL; 333 cctx->rid = rid; 334 cmd = NULL; 335 cctx->env = NULL; 336 env_len = 0; 337 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 338 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 339 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 340 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 341 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 342 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 343 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 344 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 345 malf: 346 free(cmd); 347 for (j = 0; j < env_len; j++) 348 free(cctx->env[j]); 349 free(cctx->env); 350 free(cctx->term); 351 free(cctx); 352 error_f("malformed message"); 353 return -1; 354 } 355 356 #define MUX_MAX_ENV_VARS 4096 357 while (sshbuf_len(m) > 0) { 358 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 359 goto malf; 360 if (!env_permitted(cp)) { 361 free(cp); 362 continue; 363 } 364 cctx->env = xreallocarray(cctx->env, env_len + 2, 365 sizeof(*cctx->env)); 366 cctx->env[env_len++] = cp; 367 cctx->env[env_len] = NULL; 368 if (env_len > MUX_MAX_ENV_VARS) { 369 error_f(">%d environment variables received, " 370 "ignoring additional", MUX_MAX_ENV_VARS); 371 break; 372 } 373 } 374 375 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 376 "term \"%s\", cmd \"%s\", env %u", c->self, 377 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 378 cctx->want_subsys, cctx->term, cmd, env_len); 379 380 if ((cctx->cmd = sshbuf_new()) == NULL) 381 fatal_f("sshbuf_new"); 382 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 383 fatal_fr(r, "sshbuf_put"); 384 free(cmd); 385 cmd = NULL; 386 387 /* Gather fds from client */ 388 for(i = 0; i < 3; i++) { 389 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 390 error_f("failed to receive fd %d from client", i); 391 for (j = 0; j < i; j++) 392 close(new_fd[j]); 393 for (j = 0; j < env_len; j++) 394 free(cctx->env[j]); 395 free(cctx->env); 396 free(cctx->term); 397 sshbuf_free(cctx->cmd); 398 free(cctx); 399 reply_error(reply, MUX_S_FAILURE, rid, 400 "did not receive file descriptors"); 401 return -1; 402 } 403 } 404 405 debug3_f("got fds stdin %d, stdout %d, stderr %d", 406 new_fd[0], new_fd[1], new_fd[2]); 407 408 /* XXX support multiple child sessions in future */ 409 if (c->have_remote_id) { 410 debug2_f("session already open"); 411 reply_error(reply, MUX_S_FAILURE, rid, 412 "Multiple sessions not supported"); 413 cleanup: 414 close(new_fd[0]); 415 close(new_fd[1]); 416 close(new_fd[2]); 417 free(cctx->term); 418 if (env_len != 0) { 419 for (i = 0; i < env_len; i++) 420 free(cctx->env[i]); 421 free(cctx->env); 422 } 423 sshbuf_free(cctx->cmd); 424 free(cctx); 425 return 0; 426 } 427 428 if (options.control_master == SSHCTL_MASTER_ASK || 429 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 430 if (!ask_permission("Allow shared connection to %s? ", host)) { 431 debug2_f("session refused by user"); 432 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 433 "Permission denied"); 434 goto cleanup; 435 } 436 } 437 438 /* Try to pick up ttymodes from client before it goes raw */ 439 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 440 error_f("tcgetattr: %s", strerror(errno)); 441 442 /* enable nonblocking unless tty */ 443 if (!isatty(new_fd[0])) 444 set_nonblock(new_fd[0]); 445 if (!isatty(new_fd[1])) 446 set_nonblock(new_fd[1]); 447 if (!isatty(new_fd[2])) 448 set_nonblock(new_fd[2]); 449 450 window = CHAN_SES_WINDOW_DEFAULT; 451 packetmax = CHAN_SES_PACKET_DEFAULT; 452 if (cctx->want_tty) { 453 window >>= 1; 454 packetmax >>= 1; 455 } 456 457 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 458 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 459 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 460 461 nc->ctl_chan = c->self; /* link session -> control channel */ 462 c->remote_id = nc->self; /* link control -> session channel */ 463 c->have_remote_id = 1; 464 465 if (cctx->want_tty && escape_char != 0xffffffff) { 466 channel_register_filter(ssh, nc->self, 467 client_simple_escape_filter, NULL, 468 client_filter_cleanup, 469 client_new_escape_filter_ctx((int)escape_char)); 470 } 471 472 debug2_f("channel_new: %d linked to control channel %d", 473 nc->self, nc->ctl_chan); 474 475 channel_send_open(ssh, nc->self); 476 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 477 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 478 channel_register_cleanup(ssh, nc->self, 479 mux_master_session_cleanup_cb, 1); 480 481 /* reply is deferred, sent by mux_session_confirm */ 482 return 0; 483 } 484 485 static int 486 mux_master_process_alive_check(struct ssh *ssh, u_int rid, 487 Channel *c, struct sshbuf *m, struct sshbuf *reply) 488 { 489 int r; 490 491 debug2_f("channel %d: alive check", c->self); 492 493 /* prepare reply */ 494 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 495 (r = sshbuf_put_u32(reply, rid)) != 0 || 496 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 497 fatal_fr(r, "reply"); 498 499 return 0; 500 } 501 502 static int 503 mux_master_process_terminate(struct ssh *ssh, u_int rid, 504 Channel *c, struct sshbuf *m, struct sshbuf *reply) 505 { 506 debug2_f("channel %d: terminate request", c->self); 507 508 if (options.control_master == SSHCTL_MASTER_ASK || 509 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 510 if (!ask_permission("Terminate shared connection to %s? ", 511 host)) { 512 debug2_f("termination refused by user"); 513 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 514 "Permission denied"); 515 return 0; 516 } 517 } 518 519 quit_pending = 1; 520 reply_ok(reply, rid); 521 /* XXX exit happens too soon - message never makes it to client */ 522 return 0; 523 } 524 525 static char * 526 format_forward(u_int ftype, struct Forward *fwd) 527 { 528 char *ret; 529 530 switch (ftype) { 531 case MUX_FWD_LOCAL: 532 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 533 (fwd->listen_path != NULL) ? fwd->listen_path : 534 (fwd->listen_host == NULL) ? 535 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 536 fwd->listen_host, fwd->listen_port, 537 (fwd->connect_path != NULL) ? fwd->connect_path : 538 fwd->connect_host, fwd->connect_port); 539 break; 540 case MUX_FWD_DYNAMIC: 541 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 542 (fwd->listen_host == NULL) ? 543 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 544 fwd->listen_host, fwd->listen_port); 545 break; 546 case MUX_FWD_REMOTE: 547 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 548 (fwd->listen_path != NULL) ? fwd->listen_path : 549 (fwd->listen_host == NULL) ? 550 "LOCALHOST" : fwd->listen_host, 551 fwd->listen_port, 552 (fwd->connect_path != NULL) ? fwd->connect_path : 553 fwd->connect_host, fwd->connect_port); 554 break; 555 default: 556 fatal_f("unknown forward type %u", ftype); 557 } 558 return ret; 559 } 560 561 static int 562 compare_host(const char *a, const char *b) 563 { 564 if (a == NULL && b == NULL) 565 return 1; 566 if (a == NULL || b == NULL) 567 return 0; 568 return strcmp(a, b) == 0; 569 } 570 571 static int 572 compare_forward(struct Forward *a, struct Forward *b) 573 { 574 if (!compare_host(a->listen_host, b->listen_host)) 575 return 0; 576 if (!compare_host(a->listen_path, b->listen_path)) 577 return 0; 578 if (a->listen_port != b->listen_port) 579 return 0; 580 if (!compare_host(a->connect_host, b->connect_host)) 581 return 0; 582 if (!compare_host(a->connect_path, b->connect_path)) 583 return 0; 584 if (a->connect_port != b->connect_port) 585 return 0; 586 587 return 1; 588 } 589 590 static void 591 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 592 { 593 struct mux_channel_confirm_ctx *fctx = ctxt; 594 char *failmsg = NULL; 595 struct Forward *rfwd; 596 Channel *c; 597 struct sshbuf *out; 598 u_int port; 599 int r; 600 601 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 602 /* no channel for reply */ 603 error_f("unknown channel"); 604 return; 605 } 606 if ((out = sshbuf_new()) == NULL) 607 fatal_f("sshbuf_new"); 608 if (fctx->fid >= options.num_remote_forwards || 609 (options.remote_forwards[fctx->fid].connect_path == NULL && 610 options.remote_forwards[fctx->fid].connect_host == NULL)) { 611 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 612 goto fail; 613 } 614 rfwd = &options.remote_forwards[fctx->fid]; 615 debug_f("%s for: listen %d, connect %s:%d", 616 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 617 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 618 rfwd->connect_host, rfwd->connect_port); 619 if (type == SSH2_MSG_REQUEST_SUCCESS) { 620 if (rfwd->listen_port == 0) { 621 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 622 fatal_fr(r, "parse port"); 623 if (port > 65535) { 624 fatal("Invalid allocated port %u for " 625 "mux remote forward to %s:%d", port, 626 rfwd->connect_host, rfwd->connect_port); 627 } 628 rfwd->allocated_port = (int)port; 629 debug("Allocated port %u for mux remote forward" 630 " to %s:%d", rfwd->allocated_port, 631 rfwd->connect_host, rfwd->connect_port); 632 if ((r = sshbuf_put_u32(out, 633 MUX_S_REMOTE_PORT)) != 0 || 634 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 635 (r = sshbuf_put_u32(out, 636 rfwd->allocated_port)) != 0) 637 fatal_fr(r, "reply"); 638 channel_update_permission(ssh, rfwd->handle, 639 rfwd->allocated_port); 640 } else { 641 reply_ok(out, fctx->rid); 642 } 643 goto out; 644 } else { 645 if (rfwd->listen_port == 0) 646 channel_update_permission(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_f("clearing registered forwarding for listen %d, " 655 "connect %s:%d", 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_f("%s", failmsg); 667 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 668 free(failmsg); 669 out: 670 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 671 fatal_fr(r, "enqueue"); 672 sshbuf_free(out); 673 if (c->mux_pause <= 0) 674 fatal_f("mux_pause %d", c->mux_pause); 675 c->mux_pause = 0; /* start processing messages again */ 676 } 677 678 static int 679 mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 680 Channel *c, struct sshbuf *m, struct sshbuf *reply) 681 { 682 struct Forward fwd; 683 char *fwd_desc = NULL; 684 char *listen_addr, *connect_addr; 685 u_int ftype; 686 u_int lport, cport; 687 int r, i, ret = 0, freefwd = 1; 688 689 memset(&fwd, 0, sizeof(fwd)); 690 691 /* XXX - lport/cport check redundant */ 692 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 693 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 694 (r = sshbuf_get_u32(m, &lport)) != 0 || 695 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 696 (r = sshbuf_get_u32(m, &cport)) != 0 || 697 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 698 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 699 error_f("malformed message"); 700 ret = -1; 701 goto out; 702 } 703 if (*listen_addr == '\0') { 704 free(listen_addr); 705 listen_addr = NULL; 706 } 707 if (*connect_addr == '\0') { 708 free(connect_addr); 709 connect_addr = NULL; 710 } 711 712 memset(&fwd, 0, sizeof(fwd)); 713 fwd.listen_port = lport; 714 if (fwd.listen_port == PORT_STREAMLOCAL) 715 fwd.listen_path = listen_addr; 716 else 717 fwd.listen_host = listen_addr; 718 fwd.connect_port = cport; 719 if (fwd.connect_port == PORT_STREAMLOCAL) 720 fwd.connect_path = connect_addr; 721 else 722 fwd.connect_host = connect_addr; 723 724 debug2_f("channel %d: request %s", c->self, 725 (fwd_desc = format_forward(ftype, &fwd))); 726 727 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 728 ftype != MUX_FWD_DYNAMIC) { 729 logit_f("invalid forwarding type %u", ftype); 730 invalid: 731 free(listen_addr); 732 free(connect_addr); 733 reply_error(reply, MUX_S_FAILURE, rid, 734 "Invalid forwarding request"); 735 return 0; 736 } 737 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 738 logit_f("streamlocal and dynamic forwards " 739 "are mutually exclusive"); 740 goto invalid; 741 } 742 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 743 logit_f("invalid listen port %u", fwd.listen_port); 744 goto invalid; 745 } 746 if ((fwd.connect_port != PORT_STREAMLOCAL && 747 fwd.connect_port >= 65536) || 748 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 749 fwd.connect_port == 0)) { 750 logit_f("invalid connect port %u", 751 fwd.connect_port); 752 goto invalid; 753 } 754 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 755 fwd.connect_path == NULL) { 756 logit_f("missing connect host"); 757 goto invalid; 758 } 759 760 /* Skip forwards that have already been requested */ 761 switch (ftype) { 762 case MUX_FWD_LOCAL: 763 case MUX_FWD_DYNAMIC: 764 for (i = 0; i < options.num_local_forwards; i++) { 765 if (compare_forward(&fwd, 766 options.local_forwards + i)) { 767 exists: 768 debug2_f("found existing forwarding"); 769 reply_ok(reply, rid); 770 goto out; 771 } 772 } 773 break; 774 case MUX_FWD_REMOTE: 775 for (i = 0; i < options.num_remote_forwards; i++) { 776 if (!compare_forward(&fwd, options.remote_forwards + i)) 777 continue; 778 if (fwd.listen_port != 0) 779 goto exists; 780 debug2_f("found allocated port"); 781 if ((r = sshbuf_put_u32(reply, 782 MUX_S_REMOTE_PORT)) != 0 || 783 (r = sshbuf_put_u32(reply, rid)) != 0 || 784 (r = sshbuf_put_u32(reply, 785 options.remote_forwards[i].allocated_port)) != 0) 786 fatal_fr(r, "reply FWD_REMOTE"); 787 goto out; 788 } 789 break; 790 } 791 792 if (options.control_master == SSHCTL_MASTER_ASK || 793 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 794 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 795 debug2_f("forwarding refused by user"); 796 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 797 "Permission denied"); 798 goto out; 799 } 800 } 801 802 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 803 if (!channel_setup_local_fwd_listener(ssh, &fwd, 804 &options.fwd_opts)) { 805 fail: 806 logit_f("requested %s failed", fwd_desc); 807 reply_error(reply, MUX_S_FAILURE, rid, 808 "Port forwarding failed"); 809 goto out; 810 } 811 add_local_forward(&options, &fwd); 812 freefwd = 0; 813 } else { 814 struct mux_channel_confirm_ctx *fctx; 815 816 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 817 if (fwd.handle < 0) 818 goto fail; 819 add_remote_forward(&options, &fwd); 820 fctx = xcalloc(1, sizeof(*fctx)); 821 fctx->cid = c->self; 822 fctx->rid = rid; 823 fctx->fid = options.num_remote_forwards - 1; 824 client_register_global_confirm(mux_confirm_remote_forward, 825 fctx); 826 freefwd = 0; 827 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 828 /* delayed reply in mux_confirm_remote_forward */ 829 goto out; 830 } 831 reply_ok(reply, rid); 832 out: 833 free(fwd_desc); 834 if (freefwd) { 835 free(fwd.listen_host); 836 free(fwd.listen_path); 837 free(fwd.connect_host); 838 free(fwd.connect_path); 839 } 840 return ret; 841 } 842 843 static int 844 mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 845 Channel *c, struct sshbuf *m, struct sshbuf *reply) 846 { 847 struct Forward fwd, *found_fwd; 848 char *fwd_desc = NULL; 849 const char *error_reason = NULL; 850 char *listen_addr = NULL, *connect_addr = NULL; 851 u_int ftype; 852 int r, i, ret = 0; 853 u_int lport, cport; 854 855 memset(&fwd, 0, sizeof(fwd)); 856 857 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 858 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 859 (r = sshbuf_get_u32(m, &lport)) != 0 || 860 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 861 (r = sshbuf_get_u32(m, &cport)) != 0 || 862 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 863 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 864 error_f("malformed message"); 865 ret = -1; 866 goto out; 867 } 868 869 if (*listen_addr == '\0') { 870 free(listen_addr); 871 listen_addr = NULL; 872 } 873 if (*connect_addr == '\0') { 874 free(connect_addr); 875 connect_addr = NULL; 876 } 877 878 memset(&fwd, 0, sizeof(fwd)); 879 fwd.listen_port = lport; 880 if (fwd.listen_port == PORT_STREAMLOCAL) 881 fwd.listen_path = listen_addr; 882 else 883 fwd.listen_host = listen_addr; 884 fwd.connect_port = cport; 885 if (fwd.connect_port == PORT_STREAMLOCAL) 886 fwd.connect_path = connect_addr; 887 else 888 fwd.connect_host = connect_addr; 889 890 debug2_f("channel %d: request cancel %s", c->self, 891 (fwd_desc = format_forward(ftype, &fwd))); 892 893 /* make sure this has been requested */ 894 found_fwd = NULL; 895 switch (ftype) { 896 case MUX_FWD_LOCAL: 897 case MUX_FWD_DYNAMIC: 898 for (i = 0; i < options.num_local_forwards; i++) { 899 if (compare_forward(&fwd, 900 options.local_forwards + i)) { 901 found_fwd = options.local_forwards + i; 902 break; 903 } 904 } 905 break; 906 case MUX_FWD_REMOTE: 907 for (i = 0; i < options.num_remote_forwards; i++) { 908 if (compare_forward(&fwd, 909 options.remote_forwards + i)) { 910 found_fwd = options.remote_forwards + i; 911 break; 912 } 913 } 914 break; 915 } 916 917 if (found_fwd == NULL) 918 error_reason = "port not forwarded"; 919 else if (ftype == MUX_FWD_REMOTE) { 920 /* 921 * This shouldn't fail unless we confused the host/port 922 * between options.remote_forwards and permitted_opens. 923 * However, for dynamic allocated listen ports we need 924 * to use the actual listen port. 925 */ 926 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 927 error_reason = "port not in permitted opens"; 928 } else { /* local and dynamic forwards */ 929 /* Ditto */ 930 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 931 &options.fwd_opts) == -1) 932 error_reason = "port not found"; 933 } 934 935 if (error_reason != NULL) 936 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 937 else { 938 reply_ok(reply, rid); 939 free(found_fwd->listen_host); 940 free(found_fwd->listen_path); 941 free(found_fwd->connect_host); 942 free(found_fwd->connect_path); 943 found_fwd->listen_host = found_fwd->connect_host = NULL; 944 found_fwd->listen_path = found_fwd->connect_path = NULL; 945 found_fwd->listen_port = found_fwd->connect_port = 0; 946 } 947 out: 948 free(fwd_desc); 949 free(listen_addr); 950 free(connect_addr); 951 952 return ret; 953 } 954 955 static int 956 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 957 Channel *c, struct sshbuf *m, struct sshbuf *reply) 958 { 959 Channel *nc; 960 char *chost = NULL; 961 u_int cport, i, j; 962 int r, new_fd[2]; 963 struct mux_stdio_confirm_ctx *cctx; 964 965 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 966 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 967 (r = sshbuf_get_u32(m, &cport)) != 0) { 968 free(chost); 969 error_f("malformed message"); 970 return -1; 971 } 972 973 debug2_f("channel %d: stdio fwd to %s:%u", c->self, chost, cport); 974 975 /* Gather fds from client */ 976 for(i = 0; i < 2; i++) { 977 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 978 error_f("failed to receive fd %d from client", i); 979 for (j = 0; j < i; j++) 980 close(new_fd[j]); 981 free(chost); 982 983 /* prepare reply */ 984 reply_error(reply, MUX_S_FAILURE, rid, 985 "did not receive file descriptors"); 986 return -1; 987 } 988 } 989 990 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 991 992 /* XXX support multiple child sessions in future */ 993 if (c->have_remote_id) { 994 debug2_f("session already open"); 995 reply_error(reply, MUX_S_FAILURE, rid, 996 "Multiple sessions not supported"); 997 cleanup: 998 close(new_fd[0]); 999 close(new_fd[1]); 1000 free(chost); 1001 return 0; 1002 } 1003 1004 if (options.control_master == SSHCTL_MASTER_ASK || 1005 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1006 if (!ask_permission("Allow forward to %s:%u? ", 1007 chost, cport)) { 1008 debug2_f("stdio fwd refused by user"); 1009 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1010 "Permission denied"); 1011 goto cleanup; 1012 } 1013 } 1014 1015 /* enable nonblocking unless tty */ 1016 if (!isatty(new_fd[0])) 1017 set_nonblock(new_fd[0]); 1018 if (!isatty(new_fd[1])) 1019 set_nonblock(new_fd[1]); 1020 1021 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]); 1022 free(chost); 1023 1024 nc->ctl_chan = c->self; /* link session -> control channel */ 1025 c->remote_id = nc->self; /* link control -> session channel */ 1026 c->have_remote_id = 1; 1027 1028 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan); 1029 1030 channel_register_cleanup(ssh, nc->self, 1031 mux_master_session_cleanup_cb, 1); 1032 1033 cctx = xcalloc(1, sizeof(*cctx)); 1034 cctx->rid = rid; 1035 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1036 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1037 1038 /* reply is deferred, sent by mux_session_confirm */ 1039 return 0; 1040 } 1041 1042 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1043 static void 1044 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1045 { 1046 struct mux_stdio_confirm_ctx *cctx = arg; 1047 Channel *c, *cc; 1048 struct sshbuf *reply; 1049 int r; 1050 1051 if (cctx == NULL) 1052 fatal_f("cctx == NULL"); 1053 if ((c = channel_by_id(ssh, id)) == NULL) 1054 fatal_f("no channel for id %d", id); 1055 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1056 fatal_f("channel %d lacks control channel %d", 1057 id, c->ctl_chan); 1058 if ((reply = sshbuf_new()) == NULL) 1059 fatal_f("sshbuf_new"); 1060 1061 if (!success) { 1062 debug3_f("sending failure reply"); 1063 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1064 "Session open refused by peer"); 1065 /* prepare reply */ 1066 goto done; 1067 } 1068 1069 debug3_f("sending success reply"); 1070 /* prepare reply */ 1071 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1072 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1073 (r = sshbuf_put_u32(reply, c->self)) != 0) 1074 fatal_fr(r, "reply"); 1075 1076 done: 1077 /* Send reply */ 1078 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1079 fatal_fr(r, "enqueue"); 1080 sshbuf_free(reply); 1081 1082 if (cc->mux_pause <= 0) 1083 fatal_f("mux_pause %d", cc->mux_pause); 1084 cc->mux_pause = 0; /* start processing messages again */ 1085 c->open_confirm_ctx = NULL; 1086 free(cctx); 1087 } 1088 1089 static int 1090 mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1091 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1092 { 1093 debug_f("channel %d: stop listening", c->self); 1094 1095 if (options.control_master == SSHCTL_MASTER_ASK || 1096 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1097 if (!ask_permission("Disable further multiplexing on shared " 1098 "connection to %s? ", host)) { 1099 debug2_f("stop listen refused by user"); 1100 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1101 "Permission denied"); 1102 return 0; 1103 } 1104 } 1105 1106 if (mux_listener_channel != NULL) { 1107 channel_free(ssh, mux_listener_channel); 1108 client_stop_mux(); 1109 free(options.control_path); 1110 options.control_path = NULL; 1111 mux_listener_channel = NULL; 1112 muxserver_sock = -1; 1113 } 1114 1115 reply_ok(reply, rid); 1116 return 0; 1117 } 1118 1119 static int 1120 mux_master_process_proxy(struct ssh *ssh, u_int rid, 1121 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1122 { 1123 int r; 1124 1125 debug_f("channel %d: proxy request", c->self); 1126 1127 c->mux_rcb = channel_proxy_downstream; 1128 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1129 (r = sshbuf_put_u32(reply, rid)) != 0) 1130 fatal_fr(r, "reply"); 1131 1132 return 0; 1133 } 1134 1135 /* Channel callbacks fired on read/write from mux client fd */ 1136 static int 1137 mux_master_read_cb(struct ssh *ssh, Channel *c) 1138 { 1139 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1140 struct sshbuf *in = NULL, *out = NULL; 1141 u_int type, rid, i; 1142 int r, ret = -1; 1143 1144 if ((out = sshbuf_new()) == NULL) 1145 fatal_f("sshbuf_new"); 1146 1147 /* Setup ctx and */ 1148 if (c->mux_ctx == NULL) { 1149 state = xcalloc(1, sizeof(*state)); 1150 c->mux_ctx = state; 1151 channel_register_cleanup(ssh, c->self, 1152 mux_master_control_cleanup_cb, 0); 1153 1154 /* Send hello */ 1155 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1156 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1157 fatal_fr(r, "reply"); 1158 /* no extensions */ 1159 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1160 fatal_fr(r, "enqueue"); 1161 debug3_f("channel %d: hello sent", c->self); 1162 ret = 0; 1163 goto out; 1164 } 1165 1166 /* Channel code ensures that we receive whole packets */ 1167 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1168 malf: 1169 error_f("malformed message"); 1170 goto out; 1171 } 1172 1173 if ((r = sshbuf_get_u32(in, &type)) != 0) 1174 goto malf; 1175 debug3_f("channel %d packet type 0x%08x len %zu", c->self, 1176 type, sshbuf_len(in)); 1177 1178 if (type == MUX_MSG_HELLO) 1179 rid = 0; 1180 else { 1181 if (!state->hello_rcvd) { 1182 error_f("expected MUX_MSG_HELLO(0x%08x), " 1183 "received 0x%08x", MUX_MSG_HELLO, type); 1184 goto out; 1185 } 1186 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1187 goto malf; 1188 } 1189 1190 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1191 if (type == mux_master_handlers[i].type) { 1192 ret = mux_master_handlers[i].handler(ssh, rid, 1193 c, in, out); 1194 break; 1195 } 1196 } 1197 if (mux_master_handlers[i].handler == NULL) { 1198 error_f("unsupported mux message 0x%08x", type); 1199 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1200 ret = 0; 1201 } 1202 /* Enqueue reply packet */ 1203 if (sshbuf_len(out) != 0 && 1204 (r = sshbuf_put_stringb(c->output, out)) != 0) 1205 fatal_fr(r, "enqueue"); 1206 out: 1207 sshbuf_free(in); 1208 sshbuf_free(out); 1209 return ret; 1210 } 1211 1212 void 1213 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1214 { 1215 struct sshbuf *m; 1216 Channel *mux_chan; 1217 int r; 1218 1219 debug3_f("channel %d: exit message, exitval %d", c->self, exitval); 1220 1221 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1222 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1223 1224 /* Append exit message packet to control socket output queue */ 1225 if ((m = sshbuf_new()) == NULL) 1226 fatal_f("sshbuf_new"); 1227 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1228 (r = sshbuf_put_u32(m, c->self)) != 0 || 1229 (r = sshbuf_put_u32(m, exitval)) != 0 || 1230 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1231 fatal_fr(r, "reply"); 1232 sshbuf_free(m); 1233 } 1234 1235 void 1236 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1237 { 1238 struct sshbuf *m; 1239 Channel *mux_chan; 1240 int r; 1241 1242 debug3_f("channel %d: TTY alloc failed", c->self); 1243 1244 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1245 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1246 1247 /* Append exit message packet to control socket output queue */ 1248 if ((m = sshbuf_new()) == NULL) 1249 fatal_f("sshbuf_new"); 1250 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1251 (r = sshbuf_put_u32(m, c->self)) != 0 || 1252 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1253 fatal_fr(r, "reply"); 1254 sshbuf_free(m); 1255 } 1256 1257 /* Prepare a mux master to listen on a Unix domain socket. */ 1258 void 1259 muxserver_listen(struct ssh *ssh) 1260 { 1261 mode_t old_umask; 1262 char *orig_control_path = options.control_path; 1263 char rbuf[16+1]; 1264 u_int i, r; 1265 int oerrno; 1266 1267 if (options.control_path == NULL || 1268 options.control_master == SSHCTL_MASTER_NO) 1269 return; 1270 1271 debug("setting up multiplex master socket"); 1272 1273 /* 1274 * Use a temporary path before listen so we can pseudo-atomically 1275 * establish the listening socket in its final location to avoid 1276 * other processes racing in between bind() and listen() and hitting 1277 * an unready socket. 1278 */ 1279 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1280 r = arc4random_uniform(26+26+10); 1281 rbuf[i] = (r < 26) ? 'a' + r : 1282 (r < 26*2) ? 'A' + r - 26 : 1283 '0' + r - 26 - 26; 1284 } 1285 rbuf[sizeof(rbuf) - 1] = '\0'; 1286 options.control_path = NULL; 1287 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1288 debug3_f("temporary control path %s", options.control_path); 1289 1290 old_umask = umask(0177); 1291 muxserver_sock = unix_listener(options.control_path, 64, 0); 1292 oerrno = errno; 1293 umask(old_umask); 1294 if (muxserver_sock < 0) { 1295 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1296 error("ControlSocket %s already exists, " 1297 "disabling multiplexing", options.control_path); 1298 disable_mux_master: 1299 if (muxserver_sock != -1) { 1300 close(muxserver_sock); 1301 muxserver_sock = -1; 1302 } 1303 free(orig_control_path); 1304 free(options.control_path); 1305 options.control_path = NULL; 1306 options.control_master = SSHCTL_MASTER_NO; 1307 return; 1308 } else { 1309 /* unix_listener() logs the error */ 1310 cleanup_exit(255); 1311 } 1312 } 1313 1314 /* Now atomically "move" the mux socket into position */ 1315 if (link(options.control_path, orig_control_path) != 0) { 1316 if (errno != EEXIST) { 1317 fatal_f("link mux listener %s => %s: %s", 1318 options.control_path, orig_control_path, 1319 strerror(errno)); 1320 } 1321 error("ControlSocket %s already exists, disabling multiplexing", 1322 orig_control_path); 1323 unlink(options.control_path); 1324 goto disable_mux_master; 1325 } 1326 unlink(options.control_path); 1327 free(options.control_path); 1328 options.control_path = orig_control_path; 1329 1330 set_nonblock(muxserver_sock); 1331 1332 mux_listener_channel = channel_new(ssh, "mux listener", 1333 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1334 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1335 0, options.control_path, 1); 1336 mux_listener_channel->mux_rcb = mux_master_read_cb; 1337 debug3_f("mux listener channel %d fd %d", 1338 mux_listener_channel->self, mux_listener_channel->sock); 1339 } 1340 1341 /* Callback on open confirmation in mux master for a mux client session. */ 1342 static void 1343 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1344 { 1345 struct mux_session_confirm_ctx *cctx = arg; 1346 const char *display; 1347 Channel *c, *cc; 1348 int i, r; 1349 struct sshbuf *reply; 1350 1351 if (cctx == NULL) 1352 fatal_f("cctx == NULL"); 1353 if ((c = channel_by_id(ssh, id)) == NULL) 1354 fatal_f("no channel for id %d", id); 1355 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1356 fatal_f("channel %d lacks control channel %d", 1357 id, c->ctl_chan); 1358 if ((reply = sshbuf_new()) == NULL) 1359 fatal_f("sshbuf_new"); 1360 1361 if (!success) { 1362 debug3_f("sending failure reply"); 1363 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1364 "Session open refused by peer"); 1365 goto done; 1366 } 1367 1368 display = getenv("DISPLAY"); 1369 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1370 char *proto, *data; 1371 1372 /* Get reasonable local authentication information. */ 1373 if (client_x11_get_proto(ssh, display, options.xauth_location, 1374 options.forward_x11_trusted, options.forward_x11_timeout, 1375 &proto, &data) == 0) { 1376 /* Request forwarding with authentication spoofing. */ 1377 debug("Requesting X11 forwarding with authentication " 1378 "spoofing."); 1379 x11_request_forwarding_with_spoofing(ssh, id, 1380 display, proto, data, 1); 1381 /* XXX exit_on_forward_failure */ 1382 client_expect_confirm(ssh, id, "X11 forwarding", 1383 CONFIRM_WARN); 1384 } 1385 } 1386 1387 if (cctx->want_agent_fwd && options.forward_agent) { 1388 debug("Requesting authentication agent forwarding."); 1389 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1390 if ((r = sshpkt_send(ssh)) != 0) 1391 fatal_fr(r, "send"); 1392 } 1393 1394 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1395 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1396 1397 debug3_f("sending success reply"); 1398 /* prepare reply */ 1399 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1400 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1401 (r = sshbuf_put_u32(reply, c->self)) != 0) 1402 fatal_fr(r, "reply"); 1403 1404 done: 1405 /* Send reply */ 1406 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1407 fatal_fr(r, "enqueue"); 1408 sshbuf_free(reply); 1409 1410 if (cc->mux_pause <= 0) 1411 fatal_f("mux_pause %d", cc->mux_pause); 1412 cc->mux_pause = 0; /* start processing messages again */ 1413 c->open_confirm_ctx = NULL; 1414 sshbuf_free(cctx->cmd); 1415 free(cctx->term); 1416 if (cctx->env != NULL) { 1417 for (i = 0; cctx->env[i] != NULL; i++) 1418 free(cctx->env[i]); 1419 free(cctx->env); 1420 } 1421 free(cctx); 1422 } 1423 1424 /* ** Multiplexing client support */ 1425 1426 /* Exit signal handler */ 1427 static void 1428 control_client_sighandler(int signo) 1429 { 1430 muxclient_terminate = signo; 1431 } 1432 1433 /* 1434 * Relay signal handler - used to pass some signals from mux client to 1435 * mux master. 1436 */ 1437 static void 1438 control_client_sigrelay(int signo) 1439 { 1440 int save_errno = errno; 1441 1442 if (muxserver_pid > 1) 1443 kill(muxserver_pid, signo); 1444 1445 errno = save_errno; 1446 } 1447 1448 static int 1449 mux_client_read(int fd, struct sshbuf *b, size_t need) 1450 { 1451 size_t have; 1452 ssize_t len; 1453 u_char *p; 1454 struct pollfd pfd; 1455 int r; 1456 1457 pfd.fd = fd; 1458 pfd.events = POLLIN; 1459 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1460 fatal_fr(r, "reserve"); 1461 for (have = 0; have < need; ) { 1462 if (muxclient_terminate) { 1463 errno = EINTR; 1464 return -1; 1465 } 1466 len = read(fd, p + have, need - have); 1467 if (len == -1) { 1468 switch (errno) { 1469 case EAGAIN: 1470 (void)poll(&pfd, 1, -1); 1471 /* FALLTHROUGH */ 1472 case EINTR: 1473 continue; 1474 default: 1475 return -1; 1476 } 1477 } 1478 if (len == 0) { 1479 errno = EPIPE; 1480 return -1; 1481 } 1482 have += (size_t)len; 1483 } 1484 return 0; 1485 } 1486 1487 static int 1488 mux_client_write_packet(int fd, struct sshbuf *m) 1489 { 1490 struct sshbuf *queue; 1491 u_int have, need; 1492 int r, oerrno, len; 1493 const u_char *ptr; 1494 struct pollfd pfd; 1495 1496 pfd.fd = fd; 1497 pfd.events = POLLOUT; 1498 if ((queue = sshbuf_new()) == NULL) 1499 fatal_f("sshbuf_new"); 1500 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1501 fatal_fr(r, "enqueue"); 1502 1503 need = sshbuf_len(queue); 1504 ptr = sshbuf_ptr(queue); 1505 1506 for (have = 0; have < need; ) { 1507 if (muxclient_terminate) { 1508 sshbuf_free(queue); 1509 errno = EINTR; 1510 return -1; 1511 } 1512 len = write(fd, ptr + have, need - have); 1513 if (len == -1) { 1514 switch (errno) { 1515 case EAGAIN: 1516 (void)poll(&pfd, 1, -1); 1517 /* FALLTHROUGH */ 1518 case EINTR: 1519 continue; 1520 default: 1521 oerrno = errno; 1522 sshbuf_free(queue); 1523 errno = oerrno; 1524 return -1; 1525 } 1526 } 1527 if (len == 0) { 1528 sshbuf_free(queue); 1529 errno = EPIPE; 1530 return -1; 1531 } 1532 have += (u_int)len; 1533 } 1534 sshbuf_free(queue); 1535 return 0; 1536 } 1537 1538 static int 1539 mux_client_read_packet(int fd, struct sshbuf *m) 1540 { 1541 struct sshbuf *queue; 1542 size_t need, have; 1543 const u_char *ptr; 1544 int r, oerrno; 1545 1546 if ((queue = sshbuf_new()) == NULL) 1547 fatal_f("sshbuf_new"); 1548 if (mux_client_read(fd, queue, 4) != 0) { 1549 if ((oerrno = errno) == EPIPE) 1550 debug3_f("read header failed: %s", 1551 strerror(errno)); 1552 sshbuf_free(queue); 1553 errno = oerrno; 1554 return -1; 1555 } 1556 need = PEEK_U32(sshbuf_ptr(queue)); 1557 if (mux_client_read(fd, queue, need) != 0) { 1558 oerrno = errno; 1559 debug3_f("read body failed: %s", strerror(errno)); 1560 sshbuf_free(queue); 1561 errno = oerrno; 1562 return -1; 1563 } 1564 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1565 (r = sshbuf_put(m, ptr, have)) != 0) 1566 fatal_fr(r, "dequeue"); 1567 sshbuf_free(queue); 1568 return 0; 1569 } 1570 1571 static int 1572 mux_client_hello_exchange(int fd) 1573 { 1574 struct sshbuf *m; 1575 u_int type, ver; 1576 int r, ret = -1; 1577 1578 if ((m = sshbuf_new()) == NULL) 1579 fatal_f("sshbuf_new"); 1580 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1581 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1582 fatal_fr(r, "assemble hello"); 1583 /* no extensions */ 1584 1585 if (mux_client_write_packet(fd, m) != 0) { 1586 debug_f("write packet: %s", strerror(errno)); 1587 goto out; 1588 } 1589 1590 sshbuf_reset(m); 1591 1592 /* Read their HELLO */ 1593 if (mux_client_read_packet(fd, m) != 0) { 1594 debug_f("read packet failed"); 1595 goto out; 1596 } 1597 1598 if ((r = sshbuf_get_u32(m, &type)) != 0) 1599 fatal_fr(r, "parse type"); 1600 if (type != MUX_MSG_HELLO) { 1601 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1602 goto out; 1603 } 1604 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1605 fatal_fr(r, "parse version"); 1606 if (ver != SSHMUX_VER) { 1607 error("Unsupported multiplexing protocol version %d " 1608 "(expected %d)", ver, SSHMUX_VER); 1609 goto out; 1610 } 1611 debug2_f("master version %u", ver); 1612 /* No extensions are presently defined */ 1613 while (sshbuf_len(m) > 0) { 1614 char *name = NULL; 1615 1616 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1617 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1618 error_fr(r, "parse extension"); 1619 goto out; 1620 } 1621 debug2("Unrecognised master extension \"%s\"", name); 1622 free(name); 1623 } 1624 /* success */ 1625 ret = 0; 1626 out: 1627 sshbuf_free(m); 1628 return ret; 1629 } 1630 1631 static u_int 1632 mux_client_request_alive(int fd) 1633 { 1634 struct sshbuf *m; 1635 char *e; 1636 u_int pid, type, rid; 1637 int r; 1638 1639 debug3_f("entering"); 1640 1641 if ((m = sshbuf_new()) == NULL) 1642 fatal_f("sshbuf_new"); 1643 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1644 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1645 fatal_fr(r, "assemble"); 1646 1647 if (mux_client_write_packet(fd, m) != 0) 1648 fatal_f("write packet: %s", strerror(errno)); 1649 1650 sshbuf_reset(m); 1651 1652 /* Read their reply */ 1653 if (mux_client_read_packet(fd, m) != 0) { 1654 sshbuf_free(m); 1655 return 0; 1656 } 1657 1658 if ((r = sshbuf_get_u32(m, &type)) != 0) 1659 fatal_fr(r, "parse type"); 1660 if (type != MUX_S_ALIVE) { 1661 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1662 fatal_fr(r, "parse error message"); 1663 fatal_f("master returned error: %s", e); 1664 } 1665 1666 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1667 fatal_fr(r, "parse remote ID"); 1668 if (rid != muxclient_request_id) 1669 fatal_f("out of sequence reply: my id %u theirs %u", 1670 muxclient_request_id, rid); 1671 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1672 fatal_fr(r, "parse PID"); 1673 sshbuf_free(m); 1674 1675 debug3_f("done pid = %u", pid); 1676 1677 muxclient_request_id++; 1678 1679 return pid; 1680 } 1681 1682 static void 1683 mux_client_request_terminate(int fd) 1684 { 1685 struct sshbuf *m; 1686 char *e; 1687 u_int type, rid; 1688 int r; 1689 1690 debug3_f("entering"); 1691 1692 if ((m = sshbuf_new()) == NULL) 1693 fatal_f("sshbuf_new"); 1694 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1695 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1696 fatal_fr(r, "request"); 1697 1698 if (mux_client_write_packet(fd, m) != 0) 1699 fatal_f("write packet: %s", strerror(errno)); 1700 1701 sshbuf_reset(m); 1702 1703 /* Read their reply */ 1704 if (mux_client_read_packet(fd, m) != 0) { 1705 /* Remote end exited already */ 1706 if (errno == EPIPE) { 1707 sshbuf_free(m); 1708 return; 1709 } 1710 fatal_f("read from master failed: %s", strerror(errno)); 1711 } 1712 1713 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1714 (r = sshbuf_get_u32(m, &rid)) != 0) 1715 fatal_fr(r, "parse"); 1716 if (rid != muxclient_request_id) 1717 fatal_f("out of sequence reply: my id %u theirs %u", 1718 muxclient_request_id, rid); 1719 switch (type) { 1720 case MUX_S_OK: 1721 break; 1722 case MUX_S_PERMISSION_DENIED: 1723 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1724 fatal_fr(r, "parse error message"); 1725 fatal("Master refused termination request: %s", e); 1726 case MUX_S_FAILURE: 1727 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1728 fatal_fr(r, "parse error message"); 1729 fatal_f("termination request failed: %s", e); 1730 default: 1731 fatal_f("unexpected response from master 0x%08x", type); 1732 } 1733 sshbuf_free(m); 1734 muxclient_request_id++; 1735 } 1736 1737 static int 1738 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1739 { 1740 struct sshbuf *m; 1741 char *e, *fwd_desc; 1742 const char *lhost, *chost; 1743 u_int type, rid; 1744 int r; 1745 1746 fwd_desc = format_forward(ftype, fwd); 1747 debug("Requesting %s %s", 1748 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1749 free(fwd_desc); 1750 1751 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1752 if (fwd->listen_path != NULL) 1753 lhost = fwd->listen_path; 1754 else if (fwd->listen_host == NULL) 1755 lhost = ""; 1756 else if (*fwd->listen_host == '\0') 1757 lhost = "*"; 1758 else 1759 lhost = fwd->listen_host; 1760 1761 if (fwd->connect_path != NULL) 1762 chost = fwd->connect_path; 1763 else if (fwd->connect_host == NULL) 1764 chost = ""; 1765 else 1766 chost = fwd->connect_host; 1767 1768 if ((m = sshbuf_new()) == NULL) 1769 fatal_f("sshbuf_new"); 1770 if ((r = sshbuf_put_u32(m, type)) != 0 || 1771 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1772 (r = sshbuf_put_u32(m, ftype)) != 0 || 1773 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1774 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1775 (r = sshbuf_put_cstring(m, chost)) != 0 || 1776 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1777 fatal_fr(r, "request"); 1778 1779 if (mux_client_write_packet(fd, m) != 0) 1780 fatal_f("write packet: %s", strerror(errno)); 1781 1782 sshbuf_reset(m); 1783 1784 /* Read their reply */ 1785 if (mux_client_read_packet(fd, m) != 0) { 1786 sshbuf_free(m); 1787 return -1; 1788 } 1789 1790 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1791 (r = sshbuf_get_u32(m, &rid)) != 0) 1792 fatal_fr(r, "parse"); 1793 if (rid != muxclient_request_id) 1794 fatal_f("out of sequence reply: my id %u theirs %u", 1795 muxclient_request_id, rid); 1796 1797 switch (type) { 1798 case MUX_S_OK: 1799 break; 1800 case MUX_S_REMOTE_PORT: 1801 if (cancel_flag) 1802 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1803 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1804 fatal_fr(r, "parse port"); 1805 verbose("Allocated port %u for remote forward to %s:%d", 1806 fwd->allocated_port, 1807 fwd->connect_host ? fwd->connect_host : "", 1808 fwd->connect_port); 1809 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1810 fprintf(stdout, "%i\n", fwd->allocated_port); 1811 break; 1812 case MUX_S_PERMISSION_DENIED: 1813 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1814 fatal_fr(r, "parse error message"); 1815 sshbuf_free(m); 1816 error("Master refused forwarding request: %s", e); 1817 return -1; 1818 case MUX_S_FAILURE: 1819 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1820 fatal_fr(r, "parse error message"); 1821 sshbuf_free(m); 1822 error_f("forwarding request failed: %s", e); 1823 return -1; 1824 default: 1825 fatal_f("unexpected response from master 0x%08x", type); 1826 } 1827 sshbuf_free(m); 1828 1829 muxclient_request_id++; 1830 return 0; 1831 } 1832 1833 static int 1834 mux_client_forwards(int fd, int cancel_flag) 1835 { 1836 int i, ret = 0; 1837 1838 debug3_f("%s forwardings: %d local, %d remote", 1839 cancel_flag ? "cancel" : "request", 1840 options.num_local_forwards, options.num_remote_forwards); 1841 1842 /* XXX ExitOnForwardingFailure */ 1843 for (i = 0; i < options.num_local_forwards; i++) { 1844 if (mux_client_forward(fd, cancel_flag, 1845 options.local_forwards[i].connect_port == 0 ? 1846 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1847 options.local_forwards + i) != 0) 1848 ret = -1; 1849 } 1850 for (i = 0; i < options.num_remote_forwards; i++) { 1851 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1852 options.remote_forwards + i) != 0) 1853 ret = -1; 1854 } 1855 return ret; 1856 } 1857 1858 static int 1859 mux_client_request_session(int fd) 1860 { 1861 struct sshbuf *m; 1862 char *e; 1863 const char *term; 1864 u_int echar, rid, sid, esid, exitval, type, exitval_seen; 1865 extern char **environ; 1866 int r, i, rawmode; 1867 1868 debug3_f("entering"); 1869 1870 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1871 error_f("master alive request failed"); 1872 return -1; 1873 } 1874 1875 ssh_signal(SIGPIPE, SIG_IGN); 1876 1877 if (stdin_null_flag && stdfd_devnull(1, 0, 0) == -1) 1878 fatal_f("stdfd_devnull failed"); 1879 1880 if ((term = getenv("TERM")) == NULL) 1881 term = ""; 1882 echar = 0xffffffff; 1883 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1884 echar = (u_int)options.escape_char; 1885 1886 if ((m = sshbuf_new()) == NULL) 1887 fatal_f("sshbuf_new"); 1888 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1889 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1890 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1891 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1892 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1893 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1894 (r = sshbuf_put_u32(m, subsystem_flag)) != 0 || 1895 (r = sshbuf_put_u32(m, echar)) != 0 || 1896 (r = sshbuf_put_cstring(m, term)) != 0 || 1897 (r = sshbuf_put_stringb(m, command)) != 0) 1898 fatal_fr(r, "request"); 1899 1900 /* Pass environment */ 1901 if (options.num_send_env > 0 && environ != NULL) { 1902 for (i = 0; environ[i] != NULL; i++) { 1903 if (!env_permitted(environ[i])) 1904 continue; 1905 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1906 fatal_fr(r, "request sendenv"); 1907 } 1908 } 1909 for (i = 0; i < options.num_setenv; i++) { 1910 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1911 fatal_fr(r, "request setenv"); 1912 } 1913 1914 if (mux_client_write_packet(fd, m) != 0) 1915 fatal_f("write packet: %s", strerror(errno)); 1916 1917 /* Send the stdio file descriptors */ 1918 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1919 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1920 mm_send_fd(fd, STDERR_FILENO) == -1) 1921 fatal_f("send fds failed"); 1922 1923 debug3_f("session request sent"); 1924 1925 /* Read their reply */ 1926 sshbuf_reset(m); 1927 if (mux_client_read_packet(fd, m) != 0) { 1928 error_f("read from master failed: %s", strerror(errno)); 1929 sshbuf_free(m); 1930 return -1; 1931 } 1932 1933 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1934 (r = sshbuf_get_u32(m, &rid)) != 0) 1935 fatal_fr(r, "parse"); 1936 if (rid != muxclient_request_id) 1937 fatal_f("out of sequence reply: my id %u theirs %u", 1938 muxclient_request_id, rid); 1939 1940 switch (type) { 1941 case MUX_S_SESSION_OPENED: 1942 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1943 fatal_fr(r, "parse session ID"); 1944 debug_f("master session id: %u", sid); 1945 break; 1946 case MUX_S_PERMISSION_DENIED: 1947 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1948 fatal_fr(r, "parse error message"); 1949 error("Master refused session request: %s", e); 1950 sshbuf_free(m); 1951 return -1; 1952 case MUX_S_FAILURE: 1953 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1954 fatal_fr(r, "parse error message"); 1955 error_f("session request failed: %s", e); 1956 sshbuf_free(m); 1957 return -1; 1958 default: 1959 sshbuf_free(m); 1960 error_f("unexpected response from master 0x%08x", type); 1961 return -1; 1962 } 1963 muxclient_request_id++; 1964 1965 if (pledge("stdio proc tty", NULL) == -1) 1966 fatal_f("pledge(): %s", strerror(errno)); 1967 1968 ssh_signal(SIGHUP, control_client_sighandler); 1969 ssh_signal(SIGINT, control_client_sighandler); 1970 ssh_signal(SIGTERM, control_client_sighandler); 1971 ssh_signal(SIGWINCH, control_client_sigrelay); 1972 1973 rawmode = tty_flag; 1974 if (tty_flag) 1975 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1976 1977 /* 1978 * Stick around until the controlee closes the client_fd. 1979 * Before it does, it is expected to write an exit message. 1980 * This process must read the value and wait for the closure of 1981 * the client_fd; if this one closes early, the multiplex master will 1982 * terminate early too (possibly losing data). 1983 */ 1984 for (exitval = 255, exitval_seen = 0;;) { 1985 sshbuf_reset(m); 1986 if (mux_client_read_packet(fd, m) != 0) 1987 break; 1988 if ((r = sshbuf_get_u32(m, &type)) != 0) 1989 fatal_fr(r, "parse type"); 1990 switch (type) { 1991 case MUX_S_TTY_ALLOC_FAIL: 1992 if ((r = sshbuf_get_u32(m, &esid)) != 0) 1993 fatal_fr(r, "parse session ID"); 1994 if (esid != sid) 1995 fatal_f("tty alloc fail on unknown session: " 1996 "my id %u theirs %u", sid, esid); 1997 leave_raw_mode(options.request_tty == 1998 REQUEST_TTY_FORCE); 1999 rawmode = 0; 2000 continue; 2001 case MUX_S_EXIT_MESSAGE: 2002 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2003 fatal_fr(r, "parse session ID"); 2004 if (esid != sid) 2005 fatal_f("exit on unknown session: " 2006 "my id %u theirs %u", sid, esid); 2007 if (exitval_seen) 2008 fatal_f("exitval sent twice"); 2009 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2010 fatal_fr(r, "parse exitval"); 2011 exitval_seen = 1; 2012 continue; 2013 default: 2014 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2015 fatal_fr(r, "parse error message"); 2016 fatal_f("master returned error: %s", e); 2017 } 2018 } 2019 2020 close(fd); 2021 if (rawmode) 2022 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2023 2024 if (muxclient_terminate) { 2025 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2026 exitval = 255; 2027 } else if (!exitval_seen) { 2028 debug2("Control master terminated unexpectedly"); 2029 exitval = 255; 2030 } else 2031 debug2("Received exit status from master %d", exitval); 2032 2033 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 2034 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2035 2036 exit(exitval); 2037 } 2038 2039 static int 2040 mux_client_proxy(int fd) 2041 { 2042 struct sshbuf *m; 2043 char *e; 2044 u_int type, rid; 2045 int r; 2046 2047 if ((m = sshbuf_new()) == NULL) 2048 fatal_f("sshbuf_new"); 2049 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2050 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2051 fatal_fr(r, "request"); 2052 if (mux_client_write_packet(fd, m) != 0) 2053 fatal_f("write packet: %s", strerror(errno)); 2054 2055 sshbuf_reset(m); 2056 2057 /* Read their reply */ 2058 if (mux_client_read_packet(fd, m) != 0) { 2059 sshbuf_free(m); 2060 return 0; 2061 } 2062 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2063 (r = sshbuf_get_u32(m, &rid)) != 0) 2064 fatal_fr(r, "parse"); 2065 if (rid != muxclient_request_id) 2066 fatal_f("out of sequence reply: my id %u theirs %u", 2067 muxclient_request_id, rid); 2068 if (type != MUX_S_PROXY) { 2069 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2070 fatal_fr(r, "parse error message"); 2071 fatal_f("master returned error: %s", e); 2072 } 2073 sshbuf_free(m); 2074 2075 debug3_f("done"); 2076 muxclient_request_id++; 2077 return 0; 2078 } 2079 2080 static int 2081 mux_client_request_stdio_fwd(int fd) 2082 { 2083 struct sshbuf *m; 2084 char *e; 2085 u_int type, rid, sid; 2086 int r; 2087 2088 debug3_f("entering"); 2089 2090 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2091 error_f("master alive request failed"); 2092 return -1; 2093 } 2094 2095 ssh_signal(SIGPIPE, SIG_IGN); 2096 2097 if (stdin_null_flag && stdfd_devnull(1, 0, 0) == -1) 2098 fatal_f("stdfd_devnull failed"); 2099 2100 if ((m = sshbuf_new()) == NULL) 2101 fatal_f("sshbuf_new"); 2102 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2103 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2104 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2105 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2106 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2107 fatal_fr(r, "request"); 2108 2109 if (mux_client_write_packet(fd, m) != 0) 2110 fatal_f("write packet: %s", strerror(errno)); 2111 2112 /* Send the stdio file descriptors */ 2113 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2114 mm_send_fd(fd, STDOUT_FILENO) == -1) 2115 fatal_f("send fds failed"); 2116 2117 if (pledge("stdio proc tty", NULL) == -1) 2118 fatal_f("pledge(): %s", strerror(errno)); 2119 2120 debug3_f("stdio forward request sent"); 2121 2122 /* Read their reply */ 2123 sshbuf_reset(m); 2124 2125 if (mux_client_read_packet(fd, m) != 0) { 2126 error_f("read from master failed: %s", strerror(errno)); 2127 sshbuf_free(m); 2128 return -1; 2129 } 2130 2131 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2132 (r = sshbuf_get_u32(m, &rid)) != 0) 2133 fatal_fr(r, "parse"); 2134 if (rid != muxclient_request_id) 2135 fatal_f("out of sequence reply: my id %u theirs %u", 2136 muxclient_request_id, rid); 2137 switch (type) { 2138 case MUX_S_SESSION_OPENED: 2139 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2140 fatal_fr(r, "parse session ID"); 2141 debug_f("master session id: %u", sid); 2142 break; 2143 case MUX_S_PERMISSION_DENIED: 2144 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2145 fatal_fr(r, "parse error message"); 2146 sshbuf_free(m); 2147 fatal("Master refused stdio forwarding request: %s", e); 2148 case MUX_S_FAILURE: 2149 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2150 fatal_fr(r, "parse error message"); 2151 sshbuf_free(m); 2152 fatal("Stdio forwarding request failed: %s", e); 2153 default: 2154 sshbuf_free(m); 2155 error_f("unexpected response from master 0x%08x", type); 2156 return -1; 2157 } 2158 muxclient_request_id++; 2159 2160 ssh_signal(SIGHUP, control_client_sighandler); 2161 ssh_signal(SIGINT, control_client_sighandler); 2162 ssh_signal(SIGTERM, control_client_sighandler); 2163 ssh_signal(SIGWINCH, control_client_sigrelay); 2164 2165 /* 2166 * Stick around until the controlee closes the client_fd. 2167 */ 2168 sshbuf_reset(m); 2169 if (mux_client_read_packet(fd, m) != 0) { 2170 if (errno == EPIPE || 2171 (errno == EINTR && muxclient_terminate != 0)) 2172 return 0; 2173 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2174 } 2175 fatal_f("master returned unexpected message %u", type); 2176 } 2177 2178 static void 2179 mux_client_request_stop_listening(int fd) 2180 { 2181 struct sshbuf *m; 2182 char *e; 2183 u_int type, rid; 2184 int r; 2185 2186 debug3_f("entering"); 2187 2188 if ((m = sshbuf_new()) == NULL) 2189 fatal_f("sshbuf_new"); 2190 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2191 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2192 fatal_fr(r, "request"); 2193 2194 if (mux_client_write_packet(fd, m) != 0) 2195 fatal_f("write packet: %s", strerror(errno)); 2196 2197 sshbuf_reset(m); 2198 2199 /* Read their reply */ 2200 if (mux_client_read_packet(fd, m) != 0) 2201 fatal_f("read from master failed: %s", strerror(errno)); 2202 2203 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2204 (r = sshbuf_get_u32(m, &rid)) != 0) 2205 fatal_fr(r, "parse"); 2206 if (rid != muxclient_request_id) 2207 fatal_f("out of sequence reply: my id %u theirs %u", 2208 muxclient_request_id, rid); 2209 2210 switch (type) { 2211 case MUX_S_OK: 2212 break; 2213 case MUX_S_PERMISSION_DENIED: 2214 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2215 fatal_fr(r, "parse error message"); 2216 fatal("Master refused stop listening request: %s", e); 2217 case MUX_S_FAILURE: 2218 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2219 fatal_fr(r, "parse error message"); 2220 fatal_f("stop listening request failed: %s", e); 2221 default: 2222 fatal_f("unexpected response from master 0x%08x", type); 2223 } 2224 sshbuf_free(m); 2225 muxclient_request_id++; 2226 } 2227 2228 /* Multiplex client main loop. */ 2229 int 2230 muxclient(const char *path) 2231 { 2232 struct sockaddr_un addr; 2233 int sock; 2234 u_int pid; 2235 2236 if (muxclient_command == 0) { 2237 if (options.stdio_forward_host != NULL) 2238 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2239 else 2240 muxclient_command = SSHMUX_COMMAND_OPEN; 2241 } 2242 2243 switch (options.control_master) { 2244 case SSHCTL_MASTER_AUTO: 2245 case SSHCTL_MASTER_AUTO_ASK: 2246 debug("auto-mux: Trying existing master"); 2247 /* FALLTHROUGH */ 2248 case SSHCTL_MASTER_NO: 2249 break; 2250 default: 2251 return -1; 2252 } 2253 2254 memset(&addr, '\0', sizeof(addr)); 2255 addr.sun_family = AF_UNIX; 2256 2257 if (strlcpy(addr.sun_path, path, 2258 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2259 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2260 (unsigned int)sizeof(addr.sun_path)); 2261 2262 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2263 fatal_f("socket(): %s", strerror(errno)); 2264 2265 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2266 switch (muxclient_command) { 2267 case SSHMUX_COMMAND_OPEN: 2268 case SSHMUX_COMMAND_STDIO_FWD: 2269 break; 2270 default: 2271 fatal("Control socket connect(%.100s): %s", path, 2272 strerror(errno)); 2273 } 2274 if (errno == ECONNREFUSED && 2275 options.control_master != SSHCTL_MASTER_NO) { 2276 debug("Stale control socket %.100s, unlinking", path); 2277 unlink(path); 2278 } else if (errno == ENOENT) { 2279 debug("Control socket \"%.100s\" does not exist", path); 2280 } else { 2281 error("Control socket connect(%.100s): %s", path, 2282 strerror(errno)); 2283 } 2284 close(sock); 2285 return -1; 2286 } 2287 set_nonblock(sock); 2288 2289 if (mux_client_hello_exchange(sock) != 0) { 2290 error_f("master hello exchange failed"); 2291 close(sock); 2292 return -1; 2293 } 2294 2295 switch (muxclient_command) { 2296 case SSHMUX_COMMAND_ALIVE_CHECK: 2297 if ((pid = mux_client_request_alive(sock)) == 0) 2298 fatal_f("master alive check failed"); 2299 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2300 exit(0); 2301 case SSHMUX_COMMAND_TERMINATE: 2302 mux_client_request_terminate(sock); 2303 if (options.log_level != SYSLOG_LEVEL_QUIET) 2304 fprintf(stderr, "Exit request sent.\r\n"); 2305 exit(0); 2306 case SSHMUX_COMMAND_FORWARD: 2307 if (mux_client_forwards(sock, 0) != 0) 2308 fatal_f("master forward request failed"); 2309 exit(0); 2310 case SSHMUX_COMMAND_OPEN: 2311 if (mux_client_forwards(sock, 0) != 0) { 2312 error_f("master forward request failed"); 2313 return -1; 2314 } 2315 mux_client_request_session(sock); 2316 return -1; 2317 case SSHMUX_COMMAND_STDIO_FWD: 2318 mux_client_request_stdio_fwd(sock); 2319 exit(0); 2320 case SSHMUX_COMMAND_STOP: 2321 mux_client_request_stop_listening(sock); 2322 if (options.log_level != SYSLOG_LEVEL_QUIET) 2323 fprintf(stderr, "Stop listening request sent.\r\n"); 2324 exit(0); 2325 case SSHMUX_COMMAND_CANCEL_FWD: 2326 if (mux_client_forwards(sock, 1) != 0) 2327 error_f("master cancel forward request failed"); 2328 exit(0); 2329 case SSHMUX_COMMAND_PROXY: 2330 mux_client_proxy(sock); 2331 return (sock); 2332 default: 2333 fatal("unrecognised muxclient_command %d", muxclient_command); 2334 } 2335 } 2336