1 /* $OpenBSD: mux.c,v 1.96 2023/03/08 04:43:12 guenther 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 "includes.h" 21 22 #include <sys/types.h> 23 #include <sys/stat.h> 24 #include <sys/socket.h> 25 #include <sys/un.h> 26 27 #include <errno.h> 28 #include <fcntl.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 #ifdef HAVE_PATHS_H 37 #include <paths.h> 38 #endif 39 40 #ifdef HAVE_POLL_H 41 #include <poll.h> 42 #else 43 # ifdef HAVE_SYS_POLL_H 44 # include <sys/poll.h> 45 # endif 46 #endif 47 48 #ifdef HAVE_UTIL_H 49 # include <util.h> 50 #endif 51 52 #include "openbsd-compat/sys-queue.h" 53 #include "xmalloc.h" 54 #include "log.h" 55 #include "ssh.h" 56 #include "ssh2.h" 57 #include "pathnames.h" 58 #include "misc.h" 59 #include "match.h" 60 #include "sshbuf.h" 61 #include "channels.h" 62 #include "msg.h" 63 #include "packet.h" 64 #include "monitor_fdpass.h" 65 #include "sshpty.h" 66 #include "sshkey.h" 67 #include "readconf.h" 68 #include "clientloop.h" 69 #include "ssherr.h" 70 71 /* from ssh.c */ 72 extern int tty_flag; 73 extern Options options; 74 extern char *host; 75 extern struct sshbuf *command; 76 extern volatile sig_atomic_t quit_pending; 77 78 /* Context for session open confirmation callback */ 79 struct mux_session_confirm_ctx { 80 u_int want_tty; 81 u_int want_subsys; 82 u_int want_x_fwd; 83 u_int want_agent_fwd; 84 struct sshbuf *cmd; 85 char *term; 86 struct termios tio; 87 char **env; 88 u_int rid; 89 }; 90 91 /* Context for stdio fwd open confirmation callback */ 92 struct mux_stdio_confirm_ctx { 93 u_int rid; 94 }; 95 96 /* Context for global channel callback */ 97 struct mux_channel_confirm_ctx { 98 u_int cid; /* channel id */ 99 u_int rid; /* request id */ 100 int fid; /* forward id */ 101 }; 102 103 /* fd to control socket */ 104 int muxserver_sock = -1; 105 106 /* client request id */ 107 u_int muxclient_request_id = 0; 108 109 /* Multiplexing control command */ 110 u_int muxclient_command = 0; 111 112 /* Set when signalled. */ 113 static volatile sig_atomic_t muxclient_terminate = 0; 114 115 /* PID of multiplex server */ 116 static u_int muxserver_pid = 0; 117 118 static Channel *mux_listener_channel = NULL; 119 120 struct mux_master_state { 121 int hello_rcvd; 122 }; 123 124 /* mux protocol messages */ 125 #define MUX_MSG_HELLO 0x00000001 126 #define MUX_C_NEW_SESSION 0x10000002 127 #define MUX_C_ALIVE_CHECK 0x10000004 128 #define MUX_C_TERMINATE 0x10000005 129 #define MUX_C_OPEN_FWD 0x10000006 130 #define MUX_C_CLOSE_FWD 0x10000007 131 #define MUX_C_NEW_STDIO_FWD 0x10000008 132 #define MUX_C_STOP_LISTENING 0x10000009 133 #define MUX_C_PROXY 0x1000000f 134 #define MUX_S_OK 0x80000001 135 #define MUX_S_PERMISSION_DENIED 0x80000002 136 #define MUX_S_FAILURE 0x80000003 137 #define MUX_S_EXIT_MESSAGE 0x80000004 138 #define MUX_S_ALIVE 0x80000005 139 #define MUX_S_SESSION_OPENED 0x80000006 140 #define MUX_S_REMOTE_PORT 0x80000007 141 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 142 #define MUX_S_PROXY 0x8000000f 143 144 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 145 #define MUX_FWD_LOCAL 1 146 #define MUX_FWD_REMOTE 2 147 #define MUX_FWD_DYNAMIC 3 148 149 static void mux_session_confirm(struct ssh *, int, int, void *); 150 static void mux_stdio_confirm(struct ssh *, int, int, void *); 151 152 static int mux_master_process_hello(struct ssh *, u_int, 153 Channel *, struct sshbuf *, struct sshbuf *); 154 static int mux_master_process_new_session(struct ssh *, u_int, 155 Channel *, struct sshbuf *, struct sshbuf *); 156 static int mux_master_process_alive_check(struct ssh *, u_int, 157 Channel *, struct sshbuf *, struct sshbuf *); 158 static int mux_master_process_terminate(struct ssh *, u_int, 159 Channel *, struct sshbuf *, struct sshbuf *); 160 static int mux_master_process_open_fwd(struct ssh *, u_int, 161 Channel *, struct sshbuf *, struct sshbuf *); 162 static int mux_master_process_close_fwd(struct ssh *, u_int, 163 Channel *, struct sshbuf *, struct sshbuf *); 164 static int mux_master_process_stdio_fwd(struct ssh *, u_int, 165 Channel *, struct sshbuf *, struct sshbuf *); 166 static int mux_master_process_stop_listening(struct ssh *, u_int, 167 Channel *, struct sshbuf *, struct sshbuf *); 168 static int mux_master_process_proxy(struct ssh *, u_int, 169 Channel *, struct sshbuf *, struct sshbuf *); 170 171 static const struct { 172 u_int type; 173 int (*handler)(struct ssh *, u_int, Channel *, 174 struct sshbuf *, struct sshbuf *); 175 } mux_master_handlers[] = { 176 { MUX_MSG_HELLO, mux_master_process_hello }, 177 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 178 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 179 { MUX_C_TERMINATE, mux_master_process_terminate }, 180 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 181 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 182 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 183 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 184 { MUX_C_PROXY, mux_master_process_proxy }, 185 { 0, NULL } 186 }; 187 188 /* Cleanup callback fired on closure of mux client _session_ channel */ 189 static void 190 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 191 { 192 Channel *cc, *c = channel_by_id(ssh, cid); 193 194 debug3_f("entering for channel %d", cid); 195 if (c == NULL) 196 fatal_f("channel_by_id(%i) == NULL", cid); 197 if (c->ctl_chan != -1) { 198 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 199 fatal_f("channel %d missing control channel %d", 200 c->self, c->ctl_chan); 201 c->ctl_chan = -1; 202 cc->remote_id = 0; 203 cc->have_remote_id = 0; 204 chan_rcvd_oclose(ssh, cc); 205 } 206 channel_cancel_cleanup(ssh, c->self); 207 } 208 209 /* Cleanup callback fired on closure of mux client _control_ channel */ 210 static void 211 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 212 { 213 Channel *sc, *c = channel_by_id(ssh, cid); 214 215 debug3_f("entering for channel %d", cid); 216 if (c == NULL) 217 fatal_f("channel_by_id(%i) == NULL", cid); 218 if (c->have_remote_id) { 219 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 220 fatal_f("channel %d missing session channel %u", 221 c->self, c->remote_id); 222 c->remote_id = 0; 223 c->have_remote_id = 0; 224 sc->ctl_chan = -1; 225 if (sc->type != SSH_CHANNEL_OPEN && 226 sc->type != SSH_CHANNEL_OPENING) { 227 debug2_f("channel %d: not open", sc->self); 228 chan_mark_dead(ssh, sc); 229 } else { 230 if (sc->istate == CHAN_INPUT_OPEN) 231 chan_read_failed(ssh, sc); 232 if (sc->ostate == CHAN_OUTPUT_OPEN) 233 chan_write_failed(ssh, sc); 234 } 235 } 236 channel_cancel_cleanup(ssh, c->self); 237 } 238 239 /* Check mux client environment variables before passing them to mux master. */ 240 static int 241 env_permitted(const char *env) 242 { 243 u_int i; 244 int ret; 245 char name[1024], *cp; 246 247 if ((cp = strchr(env, '=')) == NULL || cp == env) 248 return 0; 249 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 250 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 251 error_f("name '%.100s...' too long", env); 252 return 0; 253 } 254 255 for (i = 0; i < options.num_send_env; i++) 256 if (match_pattern(name, options.send_env[i])) 257 return 1; 258 259 return 0; 260 } 261 262 /* Mux master protocol message handlers */ 263 264 static int 265 mux_master_process_hello(struct ssh *ssh, u_int rid, 266 Channel *c, struct sshbuf *m, struct sshbuf *reply) 267 { 268 u_int ver; 269 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 270 int r; 271 272 if (state == NULL) 273 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 274 if (state->hello_rcvd) { 275 error_f("HELLO received twice"); 276 return -1; 277 } 278 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 279 error_fr(r, "parse"); 280 return -1; 281 } 282 if (ver != SSHMUX_VER) { 283 error_f("unsupported multiplexing protocol version %u " 284 "(expected %u)", ver, SSHMUX_VER); 285 return -1; 286 } 287 debug2_f("channel %d client version %u", c->self, ver); 288 289 /* No extensions are presently defined */ 290 while (sshbuf_len(m) > 0) { 291 char *name = NULL; 292 size_t value_len = 0; 293 294 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 295 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 296 error_fr(r, "parse extension"); 297 return -1; 298 } 299 debug2_f("Unrecognised extension \"%s\" length %zu", 300 name, value_len); 301 free(name); 302 } 303 state->hello_rcvd = 1; 304 return 0; 305 } 306 307 /* Enqueue a "ok" response to the reply buffer */ 308 static void 309 reply_ok(struct sshbuf *reply, u_int rid) 310 { 311 int r; 312 313 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 314 (r = sshbuf_put_u32(reply, rid)) != 0) 315 fatal_fr(r, "reply"); 316 } 317 318 /* Enqueue an error response to the reply buffer */ 319 static void 320 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 321 { 322 int r; 323 324 if ((r = sshbuf_put_u32(reply, type)) != 0 || 325 (r = sshbuf_put_u32(reply, rid)) != 0 || 326 (r = sshbuf_put_cstring(reply, msg)) != 0) 327 fatal_fr(r, "reply"); 328 } 329 330 static int 331 mux_master_process_new_session(struct ssh *ssh, u_int rid, 332 Channel *c, struct sshbuf *m, struct sshbuf *reply) 333 { 334 Channel *nc; 335 struct mux_session_confirm_ctx *cctx; 336 char *cmd, *cp; 337 u_int i, j, env_len, escape_char, window, packetmax; 338 int r, new_fd[3]; 339 340 /* Reply for SSHMUX_COMMAND_OPEN */ 341 cctx = xcalloc(1, sizeof(*cctx)); 342 cctx->term = NULL; 343 cctx->rid = rid; 344 cmd = NULL; 345 cctx->env = NULL; 346 env_len = 0; 347 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 348 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 349 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 350 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 351 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 352 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 353 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 354 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 355 malf: 356 free(cmd); 357 for (j = 0; j < env_len; j++) 358 free(cctx->env[j]); 359 free(cctx->env); 360 free(cctx->term); 361 free(cctx); 362 error_f("malformed message"); 363 return -1; 364 } 365 366 #define MUX_MAX_ENV_VARS 4096 367 while (sshbuf_len(m) > 0) { 368 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 369 goto malf; 370 if (!env_permitted(cp)) { 371 free(cp); 372 continue; 373 } 374 cctx->env = xreallocarray(cctx->env, env_len + 2, 375 sizeof(*cctx->env)); 376 cctx->env[env_len++] = cp; 377 cctx->env[env_len] = NULL; 378 if (env_len > MUX_MAX_ENV_VARS) { 379 error_f(">%d environment variables received, " 380 "ignoring additional", MUX_MAX_ENV_VARS); 381 break; 382 } 383 } 384 385 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 386 "term \"%s\", cmd \"%s\", env %u", c->self, 387 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 388 cctx->want_subsys, cctx->term, cmd, env_len); 389 390 if ((cctx->cmd = sshbuf_new()) == NULL) 391 fatal_f("sshbuf_new"); 392 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 393 fatal_fr(r, "sshbuf_put"); 394 free(cmd); 395 cmd = NULL; 396 397 /* Gather fds from client */ 398 for(i = 0; i < 3; i++) { 399 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 400 error_f("failed to receive fd %d from client", i); 401 for (j = 0; j < i; j++) 402 close(new_fd[j]); 403 for (j = 0; j < env_len; j++) 404 free(cctx->env[j]); 405 free(cctx->env); 406 free(cctx->term); 407 sshbuf_free(cctx->cmd); 408 free(cctx); 409 reply_error(reply, MUX_S_FAILURE, rid, 410 "did not receive file descriptors"); 411 return -1; 412 } 413 } 414 415 debug3_f("got fds stdin %d, stdout %d, stderr %d", 416 new_fd[0], new_fd[1], new_fd[2]); 417 418 /* XXX support multiple child sessions in future */ 419 if (c->have_remote_id) { 420 debug2_f("session already open"); 421 reply_error(reply, MUX_S_FAILURE, rid, 422 "Multiple sessions not supported"); 423 cleanup: 424 close(new_fd[0]); 425 close(new_fd[1]); 426 close(new_fd[2]); 427 free(cctx->term); 428 if (env_len != 0) { 429 for (i = 0; i < env_len; i++) 430 free(cctx->env[i]); 431 free(cctx->env); 432 } 433 sshbuf_free(cctx->cmd); 434 free(cctx); 435 return 0; 436 } 437 438 if (options.control_master == SSHCTL_MASTER_ASK || 439 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 440 if (!ask_permission("Allow shared connection to %s? ", host)) { 441 debug2_f("session refused by user"); 442 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 443 "Permission denied"); 444 goto cleanup; 445 } 446 } 447 448 /* Try to pick up ttymodes from client before it goes raw */ 449 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 450 error_f("tcgetattr: %s", strerror(errno)); 451 452 window = CHAN_SES_WINDOW_DEFAULT; 453 packetmax = CHAN_SES_PACKET_DEFAULT; 454 if (cctx->want_tty) { 455 window >>= 1; 456 packetmax >>= 1; 457 } 458 459 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 460 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 461 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO); 462 463 nc->ctl_chan = c->self; /* link session -> control channel */ 464 c->remote_id = nc->self; /* link control -> session channel */ 465 c->have_remote_id = 1; 466 467 if (cctx->want_tty && escape_char != 0xffffffff) { 468 channel_register_filter(ssh, nc->self, 469 client_simple_escape_filter, NULL, 470 client_filter_cleanup, 471 client_new_escape_filter_ctx((int)escape_char)); 472 } 473 474 debug2_f("channel_new: %d linked to control channel %d", 475 nc->self, nc->ctl_chan); 476 477 channel_send_open(ssh, nc->self); 478 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 479 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 480 channel_register_cleanup(ssh, nc->self, 481 mux_master_session_cleanup_cb, 1); 482 483 /* reply is deferred, sent by mux_session_confirm */ 484 return 0; 485 } 486 487 static int 488 mux_master_process_alive_check(struct ssh *ssh, u_int rid, 489 Channel *c, struct sshbuf *m, struct sshbuf *reply) 490 { 491 int r; 492 493 debug2_f("channel %d: alive check", c->self); 494 495 /* prepare reply */ 496 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 497 (r = sshbuf_put_u32(reply, rid)) != 0 || 498 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 499 fatal_fr(r, "reply"); 500 501 return 0; 502 } 503 504 static int 505 mux_master_process_terminate(struct ssh *ssh, u_int rid, 506 Channel *c, struct sshbuf *m, struct sshbuf *reply) 507 { 508 debug2_f("channel %d: terminate request", c->self); 509 510 if (options.control_master == SSHCTL_MASTER_ASK || 511 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 512 if (!ask_permission("Terminate shared connection to %s? ", 513 host)) { 514 debug2_f("termination refused by user"); 515 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 516 "Permission denied"); 517 return 0; 518 } 519 } 520 521 quit_pending = 1; 522 reply_ok(reply, rid); 523 /* XXX exit happens too soon - message never makes it to client */ 524 return 0; 525 } 526 527 static char * 528 format_forward(u_int ftype, struct Forward *fwd) 529 { 530 char *ret; 531 532 switch (ftype) { 533 case MUX_FWD_LOCAL: 534 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 535 (fwd->listen_path != NULL) ? fwd->listen_path : 536 (fwd->listen_host == NULL) ? 537 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 538 fwd->listen_host, fwd->listen_port, 539 (fwd->connect_path != NULL) ? fwd->connect_path : 540 fwd->connect_host, fwd->connect_port); 541 break; 542 case MUX_FWD_DYNAMIC: 543 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 544 (fwd->listen_host == NULL) ? 545 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 546 fwd->listen_host, fwd->listen_port); 547 break; 548 case MUX_FWD_REMOTE: 549 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 550 (fwd->listen_path != NULL) ? fwd->listen_path : 551 (fwd->listen_host == NULL) ? 552 "LOCALHOST" : fwd->listen_host, 553 fwd->listen_port, 554 (fwd->connect_path != NULL) ? fwd->connect_path : 555 fwd->connect_host, fwd->connect_port); 556 break; 557 default: 558 fatal_f("unknown forward type %u", ftype); 559 } 560 return ret; 561 } 562 563 static int 564 compare_host(const char *a, const char *b) 565 { 566 if (a == NULL && b == NULL) 567 return 1; 568 if (a == NULL || b == NULL) 569 return 0; 570 return strcmp(a, b) == 0; 571 } 572 573 static int 574 compare_forward(struct Forward *a, struct Forward *b) 575 { 576 if (!compare_host(a->listen_host, b->listen_host)) 577 return 0; 578 if (!compare_host(a->listen_path, b->listen_path)) 579 return 0; 580 if (a->listen_port != b->listen_port) 581 return 0; 582 if (!compare_host(a->connect_host, b->connect_host)) 583 return 0; 584 if (!compare_host(a->connect_path, b->connect_path)) 585 return 0; 586 if (a->connect_port != b->connect_port) 587 return 0; 588 589 return 1; 590 } 591 592 static void 593 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 594 { 595 struct mux_channel_confirm_ctx *fctx = ctxt; 596 char *failmsg = NULL; 597 struct Forward *rfwd; 598 Channel *c; 599 struct sshbuf *out; 600 u_int port; 601 int r; 602 603 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 604 /* no channel for reply */ 605 error_f("unknown channel"); 606 return; 607 } 608 if ((out = sshbuf_new()) == NULL) 609 fatal_f("sshbuf_new"); 610 if (fctx->fid >= options.num_remote_forwards || 611 (options.remote_forwards[fctx->fid].connect_path == NULL && 612 options.remote_forwards[fctx->fid].connect_host == NULL)) { 613 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 614 goto fail; 615 } 616 rfwd = &options.remote_forwards[fctx->fid]; 617 debug_f("%s for: listen %d, connect %s:%d", 618 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 619 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 620 rfwd->connect_host, rfwd->connect_port); 621 if (type == SSH2_MSG_REQUEST_SUCCESS) { 622 if (rfwd->listen_port == 0) { 623 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 624 fatal_fr(r, "parse port"); 625 if (port > 65535) { 626 fatal("Invalid allocated port %u for " 627 "mux remote forward to %s:%d", port, 628 rfwd->connect_host, rfwd->connect_port); 629 } 630 rfwd->allocated_port = (int)port; 631 debug("Allocated port %u for mux remote forward" 632 " to %s:%d", rfwd->allocated_port, 633 rfwd->connect_host, rfwd->connect_port); 634 if ((r = sshbuf_put_u32(out, 635 MUX_S_REMOTE_PORT)) != 0 || 636 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 637 (r = sshbuf_put_u32(out, 638 rfwd->allocated_port)) != 0) 639 fatal_fr(r, "reply"); 640 channel_update_permission(ssh, rfwd->handle, 641 rfwd->allocated_port); 642 } else { 643 reply_ok(out, fctx->rid); 644 } 645 goto out; 646 } else { 647 if (rfwd->listen_port == 0) 648 channel_update_permission(ssh, rfwd->handle, -1); 649 if (rfwd->listen_path != NULL) 650 xasprintf(&failmsg, "remote port forwarding failed for " 651 "listen path %s", rfwd->listen_path); 652 else 653 xasprintf(&failmsg, "remote port forwarding failed for " 654 "listen port %d", rfwd->listen_port); 655 656 debug2_f("clearing registered forwarding for listen %d, " 657 "connect %s:%d", rfwd->listen_port, 658 rfwd->connect_path ? rfwd->connect_path : 659 rfwd->connect_host, rfwd->connect_port); 660 661 free(rfwd->listen_host); 662 free(rfwd->listen_path); 663 free(rfwd->connect_host); 664 free(rfwd->connect_path); 665 memset(rfwd, 0, sizeof(*rfwd)); 666 } 667 fail: 668 error_f("%s", failmsg); 669 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 670 free(failmsg); 671 out: 672 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 673 fatal_fr(r, "enqueue"); 674 sshbuf_free(out); 675 if (c->mux_pause <= 0) 676 fatal_f("mux_pause %d", c->mux_pause); 677 c->mux_pause = 0; /* start processing messages again */ 678 } 679 680 static int 681 mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 682 Channel *c, struct sshbuf *m, struct sshbuf *reply) 683 { 684 struct Forward fwd; 685 char *fwd_desc = NULL; 686 char *listen_addr, *connect_addr; 687 u_int ftype; 688 u_int lport, cport; 689 int r, i, ret = 0, freefwd = 1; 690 691 memset(&fwd, 0, sizeof(fwd)); 692 693 /* XXX - lport/cport check redundant */ 694 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 695 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 696 (r = sshbuf_get_u32(m, &lport)) != 0 || 697 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 698 (r = sshbuf_get_u32(m, &cport)) != 0 || 699 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 700 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 701 error_f("malformed message"); 702 ret = -1; 703 goto out; 704 } 705 if (*listen_addr == '\0') { 706 free(listen_addr); 707 listen_addr = NULL; 708 } 709 if (*connect_addr == '\0') { 710 free(connect_addr); 711 connect_addr = NULL; 712 } 713 714 memset(&fwd, 0, sizeof(fwd)); 715 fwd.listen_port = lport; 716 if (fwd.listen_port == PORT_STREAMLOCAL) 717 fwd.listen_path = listen_addr; 718 else 719 fwd.listen_host = listen_addr; 720 fwd.connect_port = cport; 721 if (fwd.connect_port == PORT_STREAMLOCAL) 722 fwd.connect_path = connect_addr; 723 else 724 fwd.connect_host = connect_addr; 725 726 debug2_f("channel %d: request %s", c->self, 727 (fwd_desc = format_forward(ftype, &fwd))); 728 729 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 730 ftype != MUX_FWD_DYNAMIC) { 731 logit_f("invalid forwarding type %u", ftype); 732 invalid: 733 free(listen_addr); 734 free(connect_addr); 735 reply_error(reply, MUX_S_FAILURE, rid, 736 "Invalid forwarding request"); 737 return 0; 738 } 739 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 740 logit_f("streamlocal and dynamic forwards " 741 "are mutually exclusive"); 742 goto invalid; 743 } 744 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 745 logit_f("invalid listen port %u", fwd.listen_port); 746 goto invalid; 747 } 748 if ((fwd.connect_port != PORT_STREAMLOCAL && 749 fwd.connect_port >= 65536) || 750 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 751 fwd.connect_port == 0)) { 752 logit_f("invalid connect port %u", 753 fwd.connect_port); 754 goto invalid; 755 } 756 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 757 fwd.connect_path == NULL) { 758 logit_f("missing connect host"); 759 goto invalid; 760 } 761 762 /* Skip forwards that have already been requested */ 763 switch (ftype) { 764 case MUX_FWD_LOCAL: 765 case MUX_FWD_DYNAMIC: 766 for (i = 0; i < options.num_local_forwards; i++) { 767 if (compare_forward(&fwd, 768 options.local_forwards + i)) { 769 exists: 770 debug2_f("found existing forwarding"); 771 reply_ok(reply, rid); 772 goto out; 773 } 774 } 775 break; 776 case MUX_FWD_REMOTE: 777 for (i = 0; i < options.num_remote_forwards; i++) { 778 if (!compare_forward(&fwd, options.remote_forwards + i)) 779 continue; 780 if (fwd.listen_port != 0) 781 goto exists; 782 debug2_f("found allocated port"); 783 if ((r = sshbuf_put_u32(reply, 784 MUX_S_REMOTE_PORT)) != 0 || 785 (r = sshbuf_put_u32(reply, rid)) != 0 || 786 (r = sshbuf_put_u32(reply, 787 options.remote_forwards[i].allocated_port)) != 0) 788 fatal_fr(r, "reply FWD_REMOTE"); 789 goto out; 790 } 791 break; 792 } 793 794 if (options.control_master == SSHCTL_MASTER_ASK || 795 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 796 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 797 debug2_f("forwarding refused by user"); 798 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 799 "Permission denied"); 800 goto out; 801 } 802 } 803 804 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 805 if (!channel_setup_local_fwd_listener(ssh, &fwd, 806 &options.fwd_opts)) { 807 fail: 808 logit_f("requested %s failed", fwd_desc); 809 reply_error(reply, MUX_S_FAILURE, rid, 810 "Port forwarding failed"); 811 goto out; 812 } 813 add_local_forward(&options, &fwd); 814 freefwd = 0; 815 } else { 816 struct mux_channel_confirm_ctx *fctx; 817 818 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 819 if (fwd.handle < 0) 820 goto fail; 821 add_remote_forward(&options, &fwd); 822 fctx = xcalloc(1, sizeof(*fctx)); 823 fctx->cid = c->self; 824 fctx->rid = rid; 825 fctx->fid = options.num_remote_forwards - 1; 826 client_register_global_confirm(mux_confirm_remote_forward, 827 fctx); 828 freefwd = 0; 829 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 830 /* delayed reply in mux_confirm_remote_forward */ 831 goto out; 832 } 833 reply_ok(reply, rid); 834 out: 835 free(fwd_desc); 836 if (freefwd) { 837 free(fwd.listen_host); 838 free(fwd.listen_path); 839 free(fwd.connect_host); 840 free(fwd.connect_path); 841 } 842 return ret; 843 } 844 845 static int 846 mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 847 Channel *c, struct sshbuf *m, struct sshbuf *reply) 848 { 849 struct Forward fwd, *found_fwd; 850 char *fwd_desc = NULL; 851 const char *error_reason = NULL; 852 char *listen_addr = NULL, *connect_addr = NULL; 853 u_int ftype; 854 int r, i, ret = 0; 855 u_int lport, cport; 856 857 memset(&fwd, 0, sizeof(fwd)); 858 859 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 860 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 861 (r = sshbuf_get_u32(m, &lport)) != 0 || 862 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 863 (r = sshbuf_get_u32(m, &cport)) != 0 || 864 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 865 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 866 error_f("malformed message"); 867 ret = -1; 868 goto out; 869 } 870 871 if (*listen_addr == '\0') { 872 free(listen_addr); 873 listen_addr = NULL; 874 } 875 if (*connect_addr == '\0') { 876 free(connect_addr); 877 connect_addr = NULL; 878 } 879 880 memset(&fwd, 0, sizeof(fwd)); 881 fwd.listen_port = lport; 882 if (fwd.listen_port == PORT_STREAMLOCAL) 883 fwd.listen_path = listen_addr; 884 else 885 fwd.listen_host = listen_addr; 886 fwd.connect_port = cport; 887 if (fwd.connect_port == PORT_STREAMLOCAL) 888 fwd.connect_path = connect_addr; 889 else 890 fwd.connect_host = connect_addr; 891 892 debug2_f("channel %d: request cancel %s", c->self, 893 (fwd_desc = format_forward(ftype, &fwd))); 894 895 /* make sure this has been requested */ 896 found_fwd = NULL; 897 switch (ftype) { 898 case MUX_FWD_LOCAL: 899 case MUX_FWD_DYNAMIC: 900 for (i = 0; i < options.num_local_forwards; i++) { 901 if (compare_forward(&fwd, 902 options.local_forwards + i)) { 903 found_fwd = options.local_forwards + i; 904 break; 905 } 906 } 907 break; 908 case MUX_FWD_REMOTE: 909 for (i = 0; i < options.num_remote_forwards; i++) { 910 if (compare_forward(&fwd, 911 options.remote_forwards + i)) { 912 found_fwd = options.remote_forwards + i; 913 break; 914 } 915 } 916 break; 917 } 918 919 if (found_fwd == NULL) 920 error_reason = "port not forwarded"; 921 else if (ftype == MUX_FWD_REMOTE) { 922 /* 923 * This shouldn't fail unless we confused the host/port 924 * between options.remote_forwards and permitted_opens. 925 * However, for dynamic allocated listen ports we need 926 * to use the actual listen port. 927 */ 928 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 929 error_reason = "port not in permitted opens"; 930 } else { /* local and dynamic forwards */ 931 /* Ditto */ 932 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 933 &options.fwd_opts) == -1) 934 error_reason = "port not found"; 935 } 936 937 if (error_reason != NULL) 938 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 939 else { 940 reply_ok(reply, rid); 941 free(found_fwd->listen_host); 942 free(found_fwd->listen_path); 943 free(found_fwd->connect_host); 944 free(found_fwd->connect_path); 945 found_fwd->listen_host = found_fwd->connect_host = NULL; 946 found_fwd->listen_path = found_fwd->connect_path = NULL; 947 found_fwd->listen_port = found_fwd->connect_port = 0; 948 } 949 out: 950 free(fwd_desc); 951 free(listen_addr); 952 free(connect_addr); 953 954 return ret; 955 } 956 957 static int 958 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 959 Channel *c, struct sshbuf *m, struct sshbuf *reply) 960 { 961 Channel *nc; 962 char *chost = NULL; 963 u_int cport, i, j; 964 int r, new_fd[2]; 965 struct mux_stdio_confirm_ctx *cctx; 966 967 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 968 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 969 (r = sshbuf_get_u32(m, &cport)) != 0) { 970 free(chost); 971 error_f("malformed message"); 972 return -1; 973 } 974 975 debug2_f("channel %d: stdio fwd to %s:%u", c->self, chost, cport); 976 977 /* Gather fds from client */ 978 for(i = 0; i < 2; i++) { 979 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 980 error_f("failed to receive fd %d from client", i); 981 for (j = 0; j < i; j++) 982 close(new_fd[j]); 983 free(chost); 984 985 /* prepare reply */ 986 reply_error(reply, MUX_S_FAILURE, rid, 987 "did not receive file descriptors"); 988 return -1; 989 } 990 } 991 992 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 993 994 /* XXX support multiple child sessions in future */ 995 if (c->have_remote_id) { 996 debug2_f("session already open"); 997 reply_error(reply, MUX_S_FAILURE, rid, 998 "Multiple sessions not supported"); 999 cleanup: 1000 close(new_fd[0]); 1001 close(new_fd[1]); 1002 free(chost); 1003 return 0; 1004 } 1005 1006 if (options.control_master == SSHCTL_MASTER_ASK || 1007 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1008 if (!ask_permission("Allow forward to %s:%u? ", 1009 chost, cport)) { 1010 debug2_f("stdio fwd refused by user"); 1011 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1012 "Permission denied"); 1013 goto cleanup; 1014 } 1015 } 1016 1017 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1], 1018 CHANNEL_NONBLOCK_STDIO); 1019 free(chost); 1020 1021 nc->ctl_chan = c->self; /* link session -> control channel */ 1022 c->remote_id = nc->self; /* link control -> session channel */ 1023 c->have_remote_id = 1; 1024 1025 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan); 1026 1027 channel_register_cleanup(ssh, nc->self, 1028 mux_master_session_cleanup_cb, 1); 1029 1030 cctx = xcalloc(1, sizeof(*cctx)); 1031 cctx->rid = rid; 1032 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1033 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1034 1035 /* reply is deferred, sent by mux_session_confirm */ 1036 return 0; 1037 } 1038 1039 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1040 static void 1041 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1042 { 1043 struct mux_stdio_confirm_ctx *cctx = arg; 1044 Channel *c, *cc; 1045 struct sshbuf *reply; 1046 int r; 1047 1048 if (cctx == NULL) 1049 fatal_f("cctx == NULL"); 1050 if ((c = channel_by_id(ssh, id)) == NULL) 1051 fatal_f("no channel for id %d", id); 1052 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1053 fatal_f("channel %d lacks control channel %d", 1054 id, c->ctl_chan); 1055 if ((reply = sshbuf_new()) == NULL) 1056 fatal_f("sshbuf_new"); 1057 1058 if (!success) { 1059 debug3_f("sending failure reply"); 1060 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1061 "Session open refused by peer"); 1062 /* prepare reply */ 1063 goto done; 1064 } 1065 1066 debug3_f("sending success reply"); 1067 /* prepare reply */ 1068 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1069 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1070 (r = sshbuf_put_u32(reply, c->self)) != 0) 1071 fatal_fr(r, "reply"); 1072 1073 done: 1074 /* Send reply */ 1075 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1076 fatal_fr(r, "enqueue"); 1077 sshbuf_free(reply); 1078 1079 if (cc->mux_pause <= 0) 1080 fatal_f("mux_pause %d", cc->mux_pause); 1081 cc->mux_pause = 0; /* start processing messages again */ 1082 c->open_confirm_ctx = NULL; 1083 free(cctx); 1084 } 1085 1086 static int 1087 mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1088 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1089 { 1090 debug_f("channel %d: stop listening", c->self); 1091 1092 if (options.control_master == SSHCTL_MASTER_ASK || 1093 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1094 if (!ask_permission("Disable further multiplexing on shared " 1095 "connection to %s? ", host)) { 1096 debug2_f("stop listen refused by user"); 1097 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1098 "Permission denied"); 1099 return 0; 1100 } 1101 } 1102 1103 if (mux_listener_channel != NULL) { 1104 channel_free(ssh, mux_listener_channel); 1105 client_stop_mux(); 1106 free(options.control_path); 1107 options.control_path = NULL; 1108 mux_listener_channel = NULL; 1109 muxserver_sock = -1; 1110 } 1111 1112 reply_ok(reply, rid); 1113 return 0; 1114 } 1115 1116 static int 1117 mux_master_process_proxy(struct ssh *ssh, u_int rid, 1118 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1119 { 1120 int r; 1121 1122 debug_f("channel %d: proxy request", c->self); 1123 1124 c->mux_rcb = channel_proxy_downstream; 1125 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1126 (r = sshbuf_put_u32(reply, rid)) != 0) 1127 fatal_fr(r, "reply"); 1128 1129 return 0; 1130 } 1131 1132 /* Channel callbacks fired on read/write from mux client fd */ 1133 static int 1134 mux_master_read_cb(struct ssh *ssh, Channel *c) 1135 { 1136 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1137 struct sshbuf *in = NULL, *out = NULL; 1138 u_int type, rid, i; 1139 int r, ret = -1; 1140 1141 if ((out = sshbuf_new()) == NULL) 1142 fatal_f("sshbuf_new"); 1143 1144 /* Setup ctx and */ 1145 if (c->mux_ctx == NULL) { 1146 state = xcalloc(1, sizeof(*state)); 1147 c->mux_ctx = state; 1148 channel_register_cleanup(ssh, c->self, 1149 mux_master_control_cleanup_cb, 0); 1150 1151 /* Send hello */ 1152 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1153 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1154 fatal_fr(r, "reply"); 1155 /* no extensions */ 1156 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1157 fatal_fr(r, "enqueue"); 1158 debug3_f("channel %d: hello sent", c->self); 1159 ret = 0; 1160 goto out; 1161 } 1162 1163 /* Channel code ensures that we receive whole packets */ 1164 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1165 malf: 1166 error_f("malformed message"); 1167 goto out; 1168 } 1169 1170 if ((r = sshbuf_get_u32(in, &type)) != 0) 1171 goto malf; 1172 debug3_f("channel %d packet type 0x%08x len %zu", c->self, 1173 type, sshbuf_len(in)); 1174 1175 if (type == MUX_MSG_HELLO) 1176 rid = 0; 1177 else { 1178 if (!state->hello_rcvd) { 1179 error_f("expected MUX_MSG_HELLO(0x%08x), " 1180 "received 0x%08x", MUX_MSG_HELLO, type); 1181 goto out; 1182 } 1183 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1184 goto malf; 1185 } 1186 1187 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1188 if (type == mux_master_handlers[i].type) { 1189 ret = mux_master_handlers[i].handler(ssh, rid, 1190 c, in, out); 1191 break; 1192 } 1193 } 1194 if (mux_master_handlers[i].handler == NULL) { 1195 error_f("unsupported mux message 0x%08x", type); 1196 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1197 ret = 0; 1198 } 1199 /* Enqueue reply packet */ 1200 if (sshbuf_len(out) != 0 && 1201 (r = sshbuf_put_stringb(c->output, out)) != 0) 1202 fatal_fr(r, "enqueue"); 1203 out: 1204 sshbuf_free(in); 1205 sshbuf_free(out); 1206 return ret; 1207 } 1208 1209 void 1210 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1211 { 1212 struct sshbuf *m; 1213 Channel *mux_chan; 1214 int r; 1215 1216 debug3_f("channel %d: exit message, exitval %d", c->self, exitval); 1217 1218 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1219 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1220 1221 /* Append exit message packet to control socket output queue */ 1222 if ((m = sshbuf_new()) == NULL) 1223 fatal_f("sshbuf_new"); 1224 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1225 (r = sshbuf_put_u32(m, c->self)) != 0 || 1226 (r = sshbuf_put_u32(m, exitval)) != 0 || 1227 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1228 fatal_fr(r, "reply"); 1229 sshbuf_free(m); 1230 } 1231 1232 void 1233 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1234 { 1235 struct sshbuf *m; 1236 Channel *mux_chan; 1237 int r; 1238 1239 debug3_f("channel %d: TTY alloc failed", c->self); 1240 1241 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1242 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1243 1244 /* Append exit message packet to control socket output queue */ 1245 if ((m = sshbuf_new()) == NULL) 1246 fatal_f("sshbuf_new"); 1247 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1248 (r = sshbuf_put_u32(m, c->self)) != 0 || 1249 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1250 fatal_fr(r, "reply"); 1251 sshbuf_free(m); 1252 } 1253 1254 /* Prepare a mux master to listen on a Unix domain socket. */ 1255 void 1256 muxserver_listen(struct ssh *ssh) 1257 { 1258 mode_t old_umask; 1259 char *orig_control_path = options.control_path; 1260 char rbuf[16+1]; 1261 u_int i, r; 1262 int oerrno; 1263 1264 if (options.control_path == NULL || 1265 options.control_master == SSHCTL_MASTER_NO) 1266 return; 1267 1268 debug("setting up multiplex master socket"); 1269 1270 /* 1271 * Use a temporary path before listen so we can pseudo-atomically 1272 * establish the listening socket in its final location to avoid 1273 * other processes racing in between bind() and listen() and hitting 1274 * an unready socket. 1275 */ 1276 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1277 r = arc4random_uniform(26+26+10); 1278 rbuf[i] = (r < 26) ? 'a' + r : 1279 (r < 26*2) ? 'A' + r - 26 : 1280 '0' + r - 26 - 26; 1281 } 1282 rbuf[sizeof(rbuf) - 1] = '\0'; 1283 options.control_path = NULL; 1284 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1285 debug3_f("temporary control path %s", options.control_path); 1286 1287 old_umask = umask(0177); 1288 muxserver_sock = unix_listener(options.control_path, 64, 0); 1289 oerrno = errno; 1290 umask(old_umask); 1291 if (muxserver_sock < 0) { 1292 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1293 error("ControlSocket %s already exists, " 1294 "disabling multiplexing", options.control_path); 1295 disable_mux_master: 1296 if (muxserver_sock != -1) { 1297 close(muxserver_sock); 1298 muxserver_sock = -1; 1299 } 1300 free(orig_control_path); 1301 free(options.control_path); 1302 options.control_path = NULL; 1303 options.control_master = SSHCTL_MASTER_NO; 1304 return; 1305 } else { 1306 /* unix_listener() logs the error */ 1307 cleanup_exit(255); 1308 } 1309 } 1310 1311 /* Now atomically "move" the mux socket into position */ 1312 if (link(options.control_path, orig_control_path) != 0) { 1313 if (errno != EEXIST) { 1314 fatal_f("link mux listener %s => %s: %s", 1315 options.control_path, orig_control_path, 1316 strerror(errno)); 1317 } 1318 error("ControlSocket %s already exists, disabling multiplexing", 1319 orig_control_path); 1320 unlink(options.control_path); 1321 goto disable_mux_master; 1322 } 1323 unlink(options.control_path); 1324 free(options.control_path); 1325 options.control_path = orig_control_path; 1326 1327 set_nonblock(muxserver_sock); 1328 1329 mux_listener_channel = channel_new(ssh, "mux listener", 1330 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1331 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1332 0, options.control_path, 1); 1333 mux_listener_channel->mux_rcb = mux_master_read_cb; 1334 debug3_f("mux listener channel %d fd %d", 1335 mux_listener_channel->self, mux_listener_channel->sock); 1336 } 1337 1338 /* Callback on open confirmation in mux master for a mux client session. */ 1339 static void 1340 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1341 { 1342 struct mux_session_confirm_ctx *cctx = arg; 1343 const char *display; 1344 Channel *c, *cc; 1345 int i, r; 1346 struct sshbuf *reply; 1347 1348 if (cctx == NULL) 1349 fatal_f("cctx == NULL"); 1350 if ((c = channel_by_id(ssh, id)) == NULL) 1351 fatal_f("no channel for id %d", id); 1352 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1353 fatal_f("channel %d lacks control channel %d", 1354 id, c->ctl_chan); 1355 if ((reply = sshbuf_new()) == NULL) 1356 fatal_f("sshbuf_new"); 1357 1358 if (!success) { 1359 debug3_f("sending failure reply"); 1360 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1361 "Session open refused by peer"); 1362 goto done; 1363 } 1364 1365 display = getenv("DISPLAY"); 1366 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1367 char *proto, *data; 1368 1369 /* Get reasonable local authentication information. */ 1370 if (client_x11_get_proto(ssh, display, options.xauth_location, 1371 options.forward_x11_trusted, options.forward_x11_timeout, 1372 &proto, &data) == 0) { 1373 /* Request forwarding with authentication spoofing. */ 1374 debug("Requesting X11 forwarding with authentication " 1375 "spoofing."); 1376 x11_request_forwarding_with_spoofing(ssh, id, 1377 display, proto, data, 1); 1378 /* XXX exit_on_forward_failure */ 1379 client_expect_confirm(ssh, id, "X11 forwarding", 1380 CONFIRM_WARN); 1381 } 1382 } 1383 1384 if (cctx->want_agent_fwd && options.forward_agent) { 1385 debug("Requesting authentication agent forwarding."); 1386 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1387 if ((r = sshpkt_send(ssh)) != 0) 1388 fatal_fr(r, "send"); 1389 } 1390 1391 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1392 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1393 1394 debug3_f("sending success reply"); 1395 /* prepare reply */ 1396 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1397 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1398 (r = sshbuf_put_u32(reply, c->self)) != 0) 1399 fatal_fr(r, "reply"); 1400 1401 done: 1402 /* Send reply */ 1403 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1404 fatal_fr(r, "enqueue"); 1405 sshbuf_free(reply); 1406 1407 if (cc->mux_pause <= 0) 1408 fatal_f("mux_pause %d", cc->mux_pause); 1409 cc->mux_pause = 0; /* start processing messages again */ 1410 c->open_confirm_ctx = NULL; 1411 sshbuf_free(cctx->cmd); 1412 free(cctx->term); 1413 if (cctx->env != NULL) { 1414 for (i = 0; cctx->env[i] != NULL; i++) 1415 free(cctx->env[i]); 1416 free(cctx->env); 1417 } 1418 free(cctx); 1419 } 1420 1421 /* ** Multiplexing client support */ 1422 1423 /* Exit signal handler */ 1424 static void 1425 control_client_sighandler(int signo) 1426 { 1427 muxclient_terminate = signo; 1428 } 1429 1430 /* 1431 * Relay signal handler - used to pass some signals from mux client to 1432 * mux master. 1433 */ 1434 static void 1435 control_client_sigrelay(int signo) 1436 { 1437 int save_errno = errno; 1438 1439 if (muxserver_pid > 1) 1440 kill(muxserver_pid, signo); 1441 1442 errno = save_errno; 1443 } 1444 1445 static int 1446 mux_client_read(int fd, struct sshbuf *b, size_t need) 1447 { 1448 size_t have; 1449 ssize_t len; 1450 u_char *p; 1451 struct pollfd pfd; 1452 int r; 1453 1454 pfd.fd = fd; 1455 pfd.events = POLLIN; 1456 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1457 fatal_fr(r, "reserve"); 1458 for (have = 0; have < need; ) { 1459 if (muxclient_terminate) { 1460 errno = EINTR; 1461 return -1; 1462 } 1463 len = read(fd, p + have, need - have); 1464 if (len == -1) { 1465 switch (errno) { 1466 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1467 case EWOULDBLOCK: 1468 #endif 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 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1516 case EWOULDBLOCK: 1517 #endif 1518 case EAGAIN: 1519 (void)poll(&pfd, 1, -1); 1520 /* FALLTHROUGH */ 1521 case EINTR: 1522 continue; 1523 default: 1524 oerrno = errno; 1525 sshbuf_free(queue); 1526 errno = oerrno; 1527 return -1; 1528 } 1529 } 1530 if (len == 0) { 1531 sshbuf_free(queue); 1532 errno = EPIPE; 1533 return -1; 1534 } 1535 have += (u_int)len; 1536 } 1537 sshbuf_free(queue); 1538 return 0; 1539 } 1540 1541 static int 1542 mux_client_read_packet(int fd, struct sshbuf *m) 1543 { 1544 struct sshbuf *queue; 1545 size_t need, have; 1546 const u_char *ptr; 1547 int r, oerrno; 1548 1549 if ((queue = sshbuf_new()) == NULL) 1550 fatal_f("sshbuf_new"); 1551 if (mux_client_read(fd, queue, 4) != 0) { 1552 if ((oerrno = errno) == EPIPE) 1553 debug3_f("read header failed: %s", 1554 strerror(errno)); 1555 sshbuf_free(queue); 1556 errno = oerrno; 1557 return -1; 1558 } 1559 need = PEEK_U32(sshbuf_ptr(queue)); 1560 if (mux_client_read(fd, queue, need) != 0) { 1561 oerrno = errno; 1562 debug3_f("read body failed: %s", strerror(errno)); 1563 sshbuf_free(queue); 1564 errno = oerrno; 1565 return -1; 1566 } 1567 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1568 (r = sshbuf_put(m, ptr, have)) != 0) 1569 fatal_fr(r, "dequeue"); 1570 sshbuf_free(queue); 1571 return 0; 1572 } 1573 1574 static int 1575 mux_client_hello_exchange(int fd) 1576 { 1577 struct sshbuf *m; 1578 u_int type, ver; 1579 int r, ret = -1; 1580 1581 if ((m = sshbuf_new()) == NULL) 1582 fatal_f("sshbuf_new"); 1583 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1584 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1585 fatal_fr(r, "assemble hello"); 1586 /* no extensions */ 1587 1588 if (mux_client_write_packet(fd, m) != 0) { 1589 debug_f("write packet: %s", strerror(errno)); 1590 goto out; 1591 } 1592 1593 sshbuf_reset(m); 1594 1595 /* Read their HELLO */ 1596 if (mux_client_read_packet(fd, m) != 0) { 1597 debug_f("read packet failed"); 1598 goto out; 1599 } 1600 1601 if ((r = sshbuf_get_u32(m, &type)) != 0) 1602 fatal_fr(r, "parse type"); 1603 if (type != MUX_MSG_HELLO) { 1604 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1605 goto out; 1606 } 1607 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1608 fatal_fr(r, "parse version"); 1609 if (ver != SSHMUX_VER) { 1610 error("Unsupported multiplexing protocol version %d " 1611 "(expected %d)", ver, SSHMUX_VER); 1612 goto out; 1613 } 1614 debug2_f("master version %u", ver); 1615 /* No extensions are presently defined */ 1616 while (sshbuf_len(m) > 0) { 1617 char *name = NULL; 1618 1619 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1620 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1621 error_fr(r, "parse extension"); 1622 goto out; 1623 } 1624 debug2("Unrecognised master extension \"%s\"", name); 1625 free(name); 1626 } 1627 /* success */ 1628 ret = 0; 1629 out: 1630 sshbuf_free(m); 1631 return ret; 1632 } 1633 1634 static u_int 1635 mux_client_request_alive(int fd) 1636 { 1637 struct sshbuf *m; 1638 char *e; 1639 u_int pid, type, rid; 1640 int r; 1641 1642 debug3_f("entering"); 1643 1644 if ((m = sshbuf_new()) == NULL) 1645 fatal_f("sshbuf_new"); 1646 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1647 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1648 fatal_fr(r, "assemble"); 1649 1650 if (mux_client_write_packet(fd, m) != 0) 1651 fatal_f("write packet: %s", strerror(errno)); 1652 1653 sshbuf_reset(m); 1654 1655 /* Read their reply */ 1656 if (mux_client_read_packet(fd, m) != 0) { 1657 sshbuf_free(m); 1658 return 0; 1659 } 1660 1661 if ((r = sshbuf_get_u32(m, &type)) != 0) 1662 fatal_fr(r, "parse type"); 1663 if (type != MUX_S_ALIVE) { 1664 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1665 fatal_fr(r, "parse error message"); 1666 fatal_f("master returned error: %s", e); 1667 } 1668 1669 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1670 fatal_fr(r, "parse remote ID"); 1671 if (rid != muxclient_request_id) 1672 fatal_f("out of sequence reply: my id %u theirs %u", 1673 muxclient_request_id, rid); 1674 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1675 fatal_fr(r, "parse PID"); 1676 sshbuf_free(m); 1677 1678 debug3_f("done pid = %u", pid); 1679 1680 muxclient_request_id++; 1681 1682 return pid; 1683 } 1684 1685 static void 1686 mux_client_request_terminate(int fd) 1687 { 1688 struct sshbuf *m; 1689 char *e; 1690 u_int type, rid; 1691 int r; 1692 1693 debug3_f("entering"); 1694 1695 if ((m = sshbuf_new()) == NULL) 1696 fatal_f("sshbuf_new"); 1697 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1698 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1699 fatal_fr(r, "request"); 1700 1701 if (mux_client_write_packet(fd, m) != 0) 1702 fatal_f("write packet: %s", strerror(errno)); 1703 1704 sshbuf_reset(m); 1705 1706 /* Read their reply */ 1707 if (mux_client_read_packet(fd, m) != 0) { 1708 /* Remote end exited already */ 1709 if (errno == EPIPE) { 1710 sshbuf_free(m); 1711 return; 1712 } 1713 fatal_f("read from master failed: %s", strerror(errno)); 1714 } 1715 1716 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1717 (r = sshbuf_get_u32(m, &rid)) != 0) 1718 fatal_fr(r, "parse"); 1719 if (rid != muxclient_request_id) 1720 fatal_f("out of sequence reply: my id %u theirs %u", 1721 muxclient_request_id, rid); 1722 switch (type) { 1723 case MUX_S_OK: 1724 break; 1725 case MUX_S_PERMISSION_DENIED: 1726 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1727 fatal_fr(r, "parse error message"); 1728 fatal("Master refused termination request: %s", e); 1729 case MUX_S_FAILURE: 1730 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1731 fatal_fr(r, "parse error message"); 1732 fatal_f("termination request failed: %s", e); 1733 default: 1734 fatal_f("unexpected response from master 0x%08x", type); 1735 } 1736 sshbuf_free(m); 1737 muxclient_request_id++; 1738 } 1739 1740 static int 1741 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1742 { 1743 struct sshbuf *m; 1744 char *e, *fwd_desc; 1745 const char *lhost, *chost; 1746 u_int type, rid; 1747 int r; 1748 1749 fwd_desc = format_forward(ftype, fwd); 1750 debug("Requesting %s %s", 1751 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1752 free(fwd_desc); 1753 1754 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1755 if (fwd->listen_path != NULL) 1756 lhost = fwd->listen_path; 1757 else if (fwd->listen_host == NULL) 1758 lhost = ""; 1759 else if (*fwd->listen_host == '\0') 1760 lhost = "*"; 1761 else 1762 lhost = fwd->listen_host; 1763 1764 if (fwd->connect_path != NULL) 1765 chost = fwd->connect_path; 1766 else if (fwd->connect_host == NULL) 1767 chost = ""; 1768 else 1769 chost = fwd->connect_host; 1770 1771 if ((m = sshbuf_new()) == NULL) 1772 fatal_f("sshbuf_new"); 1773 if ((r = sshbuf_put_u32(m, type)) != 0 || 1774 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1775 (r = sshbuf_put_u32(m, ftype)) != 0 || 1776 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1777 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1778 (r = sshbuf_put_cstring(m, chost)) != 0 || 1779 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1780 fatal_fr(r, "request"); 1781 1782 if (mux_client_write_packet(fd, m) != 0) 1783 fatal_f("write packet: %s", strerror(errno)); 1784 1785 sshbuf_reset(m); 1786 1787 /* Read their reply */ 1788 if (mux_client_read_packet(fd, m) != 0) { 1789 sshbuf_free(m); 1790 return -1; 1791 } 1792 1793 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1794 (r = sshbuf_get_u32(m, &rid)) != 0) 1795 fatal_fr(r, "parse"); 1796 if (rid != muxclient_request_id) 1797 fatal_f("out of sequence reply: my id %u theirs %u", 1798 muxclient_request_id, rid); 1799 1800 switch (type) { 1801 case MUX_S_OK: 1802 break; 1803 case MUX_S_REMOTE_PORT: 1804 if (cancel_flag) 1805 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1806 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1807 fatal_fr(r, "parse port"); 1808 verbose("Allocated port %u for remote forward to %s:%d", 1809 fwd->allocated_port, 1810 fwd->connect_host ? fwd->connect_host : "", 1811 fwd->connect_port); 1812 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1813 fprintf(stdout, "%i\n", fwd->allocated_port); 1814 break; 1815 case MUX_S_PERMISSION_DENIED: 1816 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1817 fatal_fr(r, "parse error message"); 1818 sshbuf_free(m); 1819 error("Master refused forwarding request: %s", e); 1820 return -1; 1821 case MUX_S_FAILURE: 1822 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1823 fatal_fr(r, "parse error message"); 1824 sshbuf_free(m); 1825 error_f("forwarding request failed: %s", e); 1826 return -1; 1827 default: 1828 fatal_f("unexpected response from master 0x%08x", type); 1829 } 1830 sshbuf_free(m); 1831 1832 muxclient_request_id++; 1833 return 0; 1834 } 1835 1836 static int 1837 mux_client_forwards(int fd, int cancel_flag) 1838 { 1839 int i, ret = 0; 1840 1841 debug3_f("%s forwardings: %d local, %d remote", 1842 cancel_flag ? "cancel" : "request", 1843 options.num_local_forwards, options.num_remote_forwards); 1844 1845 /* XXX ExitOnForwardingFailure */ 1846 for (i = 0; i < options.num_local_forwards; i++) { 1847 if (mux_client_forward(fd, cancel_flag, 1848 options.local_forwards[i].connect_port == 0 ? 1849 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1850 options.local_forwards + i) != 0) 1851 ret = -1; 1852 } 1853 for (i = 0; i < options.num_remote_forwards; i++) { 1854 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1855 options.remote_forwards + i) != 0) 1856 ret = -1; 1857 } 1858 return ret; 1859 } 1860 1861 static int 1862 mux_client_request_session(int fd) 1863 { 1864 struct sshbuf *m; 1865 char *e; 1866 const char *term = NULL; 1867 u_int i, echar, rid, sid, esid, exitval, type, exitval_seen; 1868 extern char **environ; 1869 int r, rawmode; 1870 1871 debug3_f("entering"); 1872 1873 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1874 error_f("master alive request failed"); 1875 return -1; 1876 } 1877 1878 ssh_signal(SIGPIPE, SIG_IGN); 1879 1880 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 1881 fatal_f("stdfd_devnull failed"); 1882 1883 if ((term = lookup_env_in_list("TERM", options.setenv, 1884 options.num_setenv)) == NULL || *term == '\0') 1885 term = getenv("TERM"); 1886 1887 echar = 0xffffffff; 1888 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1889 echar = (u_int)options.escape_char; 1890 1891 if ((m = sshbuf_new()) == NULL) 1892 fatal_f("sshbuf_new"); 1893 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1894 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1895 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1896 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1897 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1898 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1899 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 || 1900 (r = sshbuf_put_u32(m, echar)) != 0 || 1901 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 || 1902 (r = sshbuf_put_stringb(m, command)) != 0) 1903 fatal_fr(r, "request"); 1904 1905 /* Pass environment */ 1906 if (options.num_send_env > 0 && environ != NULL) { 1907 for (i = 0; environ[i] != NULL; i++) { 1908 if (!env_permitted(environ[i])) 1909 continue; 1910 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1911 fatal_fr(r, "request sendenv"); 1912 } 1913 } 1914 for (i = 0; i < options.num_setenv; i++) { 1915 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1916 fatal_fr(r, "request setenv"); 1917 } 1918 1919 if (mux_client_write_packet(fd, m) != 0) 1920 fatal_f("write packet: %s", strerror(errno)); 1921 1922 /* Send the stdio file descriptors */ 1923 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1924 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1925 mm_send_fd(fd, STDERR_FILENO) == -1) 1926 fatal_f("send fds failed"); 1927 1928 debug3_f("session request sent"); 1929 1930 /* Read their reply */ 1931 sshbuf_reset(m); 1932 if (mux_client_read_packet(fd, m) != 0) { 1933 error_f("read from master failed: %s", strerror(errno)); 1934 sshbuf_free(m); 1935 return -1; 1936 } 1937 1938 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1939 (r = sshbuf_get_u32(m, &rid)) != 0) 1940 fatal_fr(r, "parse"); 1941 if (rid != muxclient_request_id) 1942 fatal_f("out of sequence reply: my id %u theirs %u", 1943 muxclient_request_id, rid); 1944 1945 switch (type) { 1946 case MUX_S_SESSION_OPENED: 1947 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1948 fatal_fr(r, "parse session ID"); 1949 debug_f("master session id: %u", sid); 1950 break; 1951 case MUX_S_PERMISSION_DENIED: 1952 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1953 fatal_fr(r, "parse error message"); 1954 error("Master refused session request: %s", e); 1955 sshbuf_free(m); 1956 return -1; 1957 case MUX_S_FAILURE: 1958 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1959 fatal_fr(r, "parse error message"); 1960 error_f("session request failed: %s", e); 1961 sshbuf_free(m); 1962 return -1; 1963 default: 1964 sshbuf_free(m); 1965 error_f("unexpected response from master 0x%08x", type); 1966 return -1; 1967 } 1968 muxclient_request_id++; 1969 1970 if (pledge("stdio proc tty", NULL) == -1) 1971 fatal_f("pledge(): %s", strerror(errno)); 1972 platform_pledge_mux(); 1973 1974 ssh_signal(SIGHUP, control_client_sighandler); 1975 ssh_signal(SIGINT, control_client_sighandler); 1976 ssh_signal(SIGTERM, control_client_sighandler); 1977 ssh_signal(SIGWINCH, control_client_sigrelay); 1978 1979 rawmode = tty_flag; 1980 if (tty_flag) 1981 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1982 1983 /* 1984 * Stick around until the controlee closes the client_fd. 1985 * Before it does, it is expected to write an exit message. 1986 * This process must read the value and wait for the closure of 1987 * the client_fd; if this one closes early, the multiplex master will 1988 * terminate early too (possibly losing data). 1989 */ 1990 for (exitval = 255, exitval_seen = 0;;) { 1991 sshbuf_reset(m); 1992 if (mux_client_read_packet(fd, m) != 0) 1993 break; 1994 if ((r = sshbuf_get_u32(m, &type)) != 0) 1995 fatal_fr(r, "parse type"); 1996 switch (type) { 1997 case MUX_S_TTY_ALLOC_FAIL: 1998 if ((r = sshbuf_get_u32(m, &esid)) != 0) 1999 fatal_fr(r, "parse session ID"); 2000 if (esid != sid) 2001 fatal_f("tty alloc fail on unknown session: " 2002 "my id %u theirs %u", sid, esid); 2003 leave_raw_mode(options.request_tty == 2004 REQUEST_TTY_FORCE); 2005 rawmode = 0; 2006 continue; 2007 case MUX_S_EXIT_MESSAGE: 2008 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2009 fatal_fr(r, "parse session ID"); 2010 if (esid != sid) 2011 fatal_f("exit on unknown session: " 2012 "my id %u theirs %u", sid, esid); 2013 if (exitval_seen) 2014 fatal_f("exitval sent twice"); 2015 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2016 fatal_fr(r, "parse exitval"); 2017 exitval_seen = 1; 2018 continue; 2019 default: 2020 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2021 fatal_fr(r, "parse error message"); 2022 fatal_f("master returned error: %s", e); 2023 } 2024 } 2025 2026 close(fd); 2027 if (rawmode) 2028 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2029 2030 if (muxclient_terminate) { 2031 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2032 exitval = 255; 2033 } else if (!exitval_seen) { 2034 debug2("Control master terminated unexpectedly"); 2035 exitval = 255; 2036 } else 2037 debug2("Received exit status from master %d", exitval); 2038 2039 if (tty_flag && options.log_level >= SYSLOG_LEVEL_INFO) 2040 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2041 2042 exit(exitval); 2043 } 2044 2045 static int 2046 mux_client_proxy(int fd) 2047 { 2048 struct sshbuf *m; 2049 char *e; 2050 u_int type, rid; 2051 int r; 2052 2053 if ((m = sshbuf_new()) == NULL) 2054 fatal_f("sshbuf_new"); 2055 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2056 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2057 fatal_fr(r, "request"); 2058 if (mux_client_write_packet(fd, m) != 0) 2059 fatal_f("write packet: %s", strerror(errno)); 2060 2061 sshbuf_reset(m); 2062 2063 /* Read their reply */ 2064 if (mux_client_read_packet(fd, m) != 0) { 2065 sshbuf_free(m); 2066 return 0; 2067 } 2068 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2069 (r = sshbuf_get_u32(m, &rid)) != 0) 2070 fatal_fr(r, "parse"); 2071 if (rid != muxclient_request_id) 2072 fatal_f("out of sequence reply: my id %u theirs %u", 2073 muxclient_request_id, rid); 2074 if (type != MUX_S_PROXY) { 2075 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2076 fatal_fr(r, "parse error message"); 2077 fatal_f("master returned error: %s", e); 2078 } 2079 sshbuf_free(m); 2080 2081 debug3_f("done"); 2082 muxclient_request_id++; 2083 return 0; 2084 } 2085 2086 static int 2087 mux_client_request_stdio_fwd(int fd) 2088 { 2089 struct sshbuf *m; 2090 char *e; 2091 u_int type, rid, sid; 2092 int r; 2093 2094 debug3_f("entering"); 2095 2096 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2097 error_f("master alive request failed"); 2098 return -1; 2099 } 2100 2101 ssh_signal(SIGPIPE, SIG_IGN); 2102 2103 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 2104 fatal_f("stdfd_devnull failed"); 2105 2106 if ((m = sshbuf_new()) == NULL) 2107 fatal_f("sshbuf_new"); 2108 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2109 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2110 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2111 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2112 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2113 fatal_fr(r, "request"); 2114 2115 if (mux_client_write_packet(fd, m) != 0) 2116 fatal_f("write packet: %s", strerror(errno)); 2117 2118 /* Send the stdio file descriptors */ 2119 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2120 mm_send_fd(fd, STDOUT_FILENO) == -1) 2121 fatal_f("send fds failed"); 2122 2123 if (pledge("stdio proc tty", NULL) == -1) 2124 fatal_f("pledge(): %s", strerror(errno)); 2125 platform_pledge_mux(); 2126 2127 debug3_f("stdio forward request sent"); 2128 2129 /* Read their reply */ 2130 sshbuf_reset(m); 2131 2132 if (mux_client_read_packet(fd, m) != 0) { 2133 error_f("read from master failed: %s", strerror(errno)); 2134 sshbuf_free(m); 2135 return -1; 2136 } 2137 2138 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2139 (r = sshbuf_get_u32(m, &rid)) != 0) 2140 fatal_fr(r, "parse"); 2141 if (rid != muxclient_request_id) 2142 fatal_f("out of sequence reply: my id %u theirs %u", 2143 muxclient_request_id, rid); 2144 switch (type) { 2145 case MUX_S_SESSION_OPENED: 2146 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2147 fatal_fr(r, "parse session ID"); 2148 debug_f("master session id: %u", sid); 2149 break; 2150 case MUX_S_PERMISSION_DENIED: 2151 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2152 fatal_fr(r, "parse error message"); 2153 sshbuf_free(m); 2154 fatal("Master refused stdio forwarding request: %s", e); 2155 case MUX_S_FAILURE: 2156 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2157 fatal_fr(r, "parse error message"); 2158 sshbuf_free(m); 2159 fatal("Stdio forwarding request failed: %s", e); 2160 default: 2161 sshbuf_free(m); 2162 error_f("unexpected response from master 0x%08x", type); 2163 return -1; 2164 } 2165 muxclient_request_id++; 2166 2167 ssh_signal(SIGHUP, control_client_sighandler); 2168 ssh_signal(SIGINT, control_client_sighandler); 2169 ssh_signal(SIGTERM, control_client_sighandler); 2170 ssh_signal(SIGWINCH, control_client_sigrelay); 2171 2172 /* 2173 * Stick around until the controlee closes the client_fd. 2174 */ 2175 sshbuf_reset(m); 2176 if (mux_client_read_packet(fd, m) != 0) { 2177 if (errno == EPIPE || 2178 (errno == EINTR && muxclient_terminate != 0)) 2179 return 0; 2180 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2181 } 2182 fatal_f("master returned unexpected message %u", type); 2183 } 2184 2185 static void 2186 mux_client_request_stop_listening(int fd) 2187 { 2188 struct sshbuf *m; 2189 char *e; 2190 u_int type, rid; 2191 int r; 2192 2193 debug3_f("entering"); 2194 2195 if ((m = sshbuf_new()) == NULL) 2196 fatal_f("sshbuf_new"); 2197 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2198 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2199 fatal_fr(r, "request"); 2200 2201 if (mux_client_write_packet(fd, m) != 0) 2202 fatal_f("write packet: %s", strerror(errno)); 2203 2204 sshbuf_reset(m); 2205 2206 /* Read their reply */ 2207 if (mux_client_read_packet(fd, m) != 0) 2208 fatal_f("read from master failed: %s", strerror(errno)); 2209 2210 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2211 (r = sshbuf_get_u32(m, &rid)) != 0) 2212 fatal_fr(r, "parse"); 2213 if (rid != muxclient_request_id) 2214 fatal_f("out of sequence reply: my id %u theirs %u", 2215 muxclient_request_id, rid); 2216 2217 switch (type) { 2218 case MUX_S_OK: 2219 break; 2220 case MUX_S_PERMISSION_DENIED: 2221 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2222 fatal_fr(r, "parse error message"); 2223 fatal("Master refused stop listening request: %s", e); 2224 case MUX_S_FAILURE: 2225 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2226 fatal_fr(r, "parse error message"); 2227 fatal_f("stop listening request failed: %s", e); 2228 default: 2229 fatal_f("unexpected response from master 0x%08x", type); 2230 } 2231 sshbuf_free(m); 2232 muxclient_request_id++; 2233 } 2234 2235 /* Multiplex client main loop. */ 2236 int 2237 muxclient(const char *path) 2238 { 2239 struct sockaddr_un addr; 2240 int sock; 2241 u_int pid; 2242 2243 if (muxclient_command == 0) { 2244 if (options.stdio_forward_host != NULL) 2245 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2246 else 2247 muxclient_command = SSHMUX_COMMAND_OPEN; 2248 } 2249 2250 switch (options.control_master) { 2251 case SSHCTL_MASTER_AUTO: 2252 case SSHCTL_MASTER_AUTO_ASK: 2253 debug("auto-mux: Trying existing master"); 2254 /* FALLTHROUGH */ 2255 case SSHCTL_MASTER_NO: 2256 break; 2257 default: 2258 return -1; 2259 } 2260 2261 memset(&addr, '\0', sizeof(addr)); 2262 addr.sun_family = AF_UNIX; 2263 2264 if (strlcpy(addr.sun_path, path, 2265 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2266 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2267 (unsigned int)sizeof(addr.sun_path)); 2268 2269 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2270 fatal_f("socket(): %s", strerror(errno)); 2271 2272 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2273 switch (muxclient_command) { 2274 case SSHMUX_COMMAND_OPEN: 2275 case SSHMUX_COMMAND_STDIO_FWD: 2276 break; 2277 default: 2278 fatal("Control socket connect(%.100s): %s", path, 2279 strerror(errno)); 2280 } 2281 if (errno == ECONNREFUSED && 2282 options.control_master != SSHCTL_MASTER_NO) { 2283 debug("Stale control socket %.100s, unlinking", path); 2284 unlink(path); 2285 } else if (errno == ENOENT) { 2286 debug("Control socket \"%.100s\" does not exist", path); 2287 } else { 2288 error("Control socket connect(%.100s): %s", path, 2289 strerror(errno)); 2290 } 2291 close(sock); 2292 return -1; 2293 } 2294 set_nonblock(sock); 2295 2296 if (mux_client_hello_exchange(sock) != 0) { 2297 error_f("master hello exchange failed"); 2298 close(sock); 2299 return -1; 2300 } 2301 2302 switch (muxclient_command) { 2303 case SSHMUX_COMMAND_ALIVE_CHECK: 2304 if ((pid = mux_client_request_alive(sock)) == 0) 2305 fatal_f("master alive check failed"); 2306 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2307 exit(0); 2308 case SSHMUX_COMMAND_TERMINATE: 2309 mux_client_request_terminate(sock); 2310 if (options.log_level != SYSLOG_LEVEL_QUIET) 2311 fprintf(stderr, "Exit request sent.\r\n"); 2312 exit(0); 2313 case SSHMUX_COMMAND_FORWARD: 2314 if (mux_client_forwards(sock, 0) != 0) 2315 fatal_f("master forward request failed"); 2316 exit(0); 2317 case SSHMUX_COMMAND_OPEN: 2318 if (mux_client_forwards(sock, 0) != 0) { 2319 error_f("master forward request failed"); 2320 return -1; 2321 } 2322 mux_client_request_session(sock); 2323 return -1; 2324 case SSHMUX_COMMAND_STDIO_FWD: 2325 mux_client_request_stdio_fwd(sock); 2326 exit(0); 2327 case SSHMUX_COMMAND_STOP: 2328 mux_client_request_stop_listening(sock); 2329 if (options.log_level != SYSLOG_LEVEL_QUIET) 2330 fprintf(stderr, "Stop listening request sent.\r\n"); 2331 exit(0); 2332 case SSHMUX_COMMAND_CANCEL_FWD: 2333 if (mux_client_forwards(sock, 1) != 0) 2334 error_f("master cancel forward request failed"); 2335 exit(0); 2336 case SSHMUX_COMMAND_PROXY: 2337 mux_client_proxy(sock); 2338 return (sock); 2339 default: 2340 fatal("unrecognised muxclient_command %d", muxclient_command); 2341 } 2342 } 2343