1 /* $OpenBSD: mux.c,v 1.95 2023/01/06 02:39:59 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 "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 /* ARGSUSED */ 190 static void 191 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 192 { 193 Channel *cc, *c = channel_by_id(ssh, cid); 194 195 debug3_f("entering for channel %d", cid); 196 if (c == NULL) 197 fatal_f("channel_by_id(%i) == NULL", cid); 198 if (c->ctl_chan != -1) { 199 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 200 fatal_f("channel %d missing control channel %d", 201 c->self, c->ctl_chan); 202 c->ctl_chan = -1; 203 cc->remote_id = 0; 204 cc->have_remote_id = 0; 205 chan_rcvd_oclose(ssh, cc); 206 } 207 channel_cancel_cleanup(ssh, c->self); 208 } 209 210 /* Cleanup callback fired on closure of mux client _control_ channel */ 211 /* ARGSUSED */ 212 static void 213 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 214 { 215 Channel *sc, *c = channel_by_id(ssh, cid); 216 217 debug3_f("entering for channel %d", cid); 218 if (c == NULL) 219 fatal_f("channel_by_id(%i) == NULL", cid); 220 if (c->have_remote_id) { 221 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 222 fatal_f("channel %d missing session channel %u", 223 c->self, c->remote_id); 224 c->remote_id = 0; 225 c->have_remote_id = 0; 226 sc->ctl_chan = -1; 227 if (sc->type != SSH_CHANNEL_OPEN && 228 sc->type != SSH_CHANNEL_OPENING) { 229 debug2_f("channel %d: not open", sc->self); 230 chan_mark_dead(ssh, sc); 231 } else { 232 if (sc->istate == CHAN_INPUT_OPEN) 233 chan_read_failed(ssh, sc); 234 if (sc->ostate == CHAN_OUTPUT_OPEN) 235 chan_write_failed(ssh, sc); 236 } 237 } 238 channel_cancel_cleanup(ssh, c->self); 239 } 240 241 /* Check mux client environment variables before passing them to mux master. */ 242 static int 243 env_permitted(const char *env) 244 { 245 u_int i; 246 int ret; 247 char name[1024], *cp; 248 249 if ((cp = strchr(env, '=')) == NULL || cp == env) 250 return 0; 251 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 252 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 253 error_f("name '%.100s...' too long", env); 254 return 0; 255 } 256 257 for (i = 0; i < options.num_send_env; i++) 258 if (match_pattern(name, options.send_env[i])) 259 return 1; 260 261 return 0; 262 } 263 264 /* Mux master protocol message handlers */ 265 266 static int 267 mux_master_process_hello(struct ssh *ssh, u_int rid, 268 Channel *c, struct sshbuf *m, struct sshbuf *reply) 269 { 270 u_int ver; 271 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 272 int r; 273 274 if (state == NULL) 275 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 276 if (state->hello_rcvd) { 277 error_f("HELLO received twice"); 278 return -1; 279 } 280 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 281 error_fr(r, "parse"); 282 return -1; 283 } 284 if (ver != SSHMUX_VER) { 285 error_f("unsupported multiplexing protocol version %u " 286 "(expected %u)", ver, SSHMUX_VER); 287 return -1; 288 } 289 debug2_f("channel %d client version %u", c->self, ver); 290 291 /* No extensions are presently defined */ 292 while (sshbuf_len(m) > 0) { 293 char *name = NULL; 294 size_t value_len = 0; 295 296 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 297 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 298 error_fr(r, "parse extension"); 299 return -1; 300 } 301 debug2_f("Unrecognised extension \"%s\" length %zu", 302 name, value_len); 303 free(name); 304 } 305 state->hello_rcvd = 1; 306 return 0; 307 } 308 309 /* Enqueue a "ok" response to the reply buffer */ 310 static void 311 reply_ok(struct sshbuf *reply, u_int rid) 312 { 313 int r; 314 315 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 316 (r = sshbuf_put_u32(reply, rid)) != 0) 317 fatal_fr(r, "reply"); 318 } 319 320 /* Enqueue an error response to the reply buffer */ 321 static void 322 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 323 { 324 int r; 325 326 if ((r = sshbuf_put_u32(reply, type)) != 0 || 327 (r = sshbuf_put_u32(reply, rid)) != 0 || 328 (r = sshbuf_put_cstring(reply, msg)) != 0) 329 fatal_fr(r, "reply"); 330 } 331 332 static int 333 mux_master_process_new_session(struct ssh *ssh, u_int rid, 334 Channel *c, struct sshbuf *m, struct sshbuf *reply) 335 { 336 Channel *nc; 337 struct mux_session_confirm_ctx *cctx; 338 char *cmd, *cp; 339 u_int i, j, env_len, escape_char, window, packetmax; 340 int r, new_fd[3]; 341 342 /* Reply for SSHMUX_COMMAND_OPEN */ 343 cctx = xcalloc(1, sizeof(*cctx)); 344 cctx->term = NULL; 345 cctx->rid = rid; 346 cmd = NULL; 347 cctx->env = NULL; 348 env_len = 0; 349 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 350 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 351 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 352 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 353 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 354 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 355 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 356 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 357 malf: 358 free(cmd); 359 for (j = 0; j < env_len; j++) 360 free(cctx->env[j]); 361 free(cctx->env); 362 free(cctx->term); 363 free(cctx); 364 error_f("malformed message"); 365 return -1; 366 } 367 368 #define MUX_MAX_ENV_VARS 4096 369 while (sshbuf_len(m) > 0) { 370 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 371 goto malf; 372 if (!env_permitted(cp)) { 373 free(cp); 374 continue; 375 } 376 cctx->env = xreallocarray(cctx->env, env_len + 2, 377 sizeof(*cctx->env)); 378 cctx->env[env_len++] = cp; 379 cctx->env[env_len] = NULL; 380 if (env_len > MUX_MAX_ENV_VARS) { 381 error_f(">%d environment variables received, " 382 "ignoring additional", MUX_MAX_ENV_VARS); 383 break; 384 } 385 } 386 387 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 388 "term \"%s\", cmd \"%s\", env %u", c->self, 389 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 390 cctx->want_subsys, cctx->term, cmd, env_len); 391 392 if ((cctx->cmd = sshbuf_new()) == NULL) 393 fatal_f("sshbuf_new"); 394 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 395 fatal_fr(r, "sshbuf_put"); 396 free(cmd); 397 cmd = NULL; 398 399 /* Gather fds from client */ 400 for(i = 0; i < 3; i++) { 401 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 402 error_f("failed to receive fd %d from client", i); 403 for (j = 0; j < i; j++) 404 close(new_fd[j]); 405 for (j = 0; j < env_len; j++) 406 free(cctx->env[j]); 407 free(cctx->env); 408 free(cctx->term); 409 sshbuf_free(cctx->cmd); 410 free(cctx); 411 reply_error(reply, MUX_S_FAILURE, rid, 412 "did not receive file descriptors"); 413 return -1; 414 } 415 } 416 417 debug3_f("got fds stdin %d, stdout %d, stderr %d", 418 new_fd[0], new_fd[1], new_fd[2]); 419 420 /* XXX support multiple child sessions in future */ 421 if (c->have_remote_id) { 422 debug2_f("session already open"); 423 reply_error(reply, MUX_S_FAILURE, rid, 424 "Multiple sessions not supported"); 425 cleanup: 426 close(new_fd[0]); 427 close(new_fd[1]); 428 close(new_fd[2]); 429 free(cctx->term); 430 if (env_len != 0) { 431 for (i = 0; i < env_len; i++) 432 free(cctx->env[i]); 433 free(cctx->env); 434 } 435 sshbuf_free(cctx->cmd); 436 free(cctx); 437 return 0; 438 } 439 440 if (options.control_master == SSHCTL_MASTER_ASK || 441 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 442 if (!ask_permission("Allow shared connection to %s? ", host)) { 443 debug2_f("session refused by user"); 444 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 445 "Permission denied"); 446 goto cleanup; 447 } 448 } 449 450 /* Try to pick up ttymodes from client before it goes raw */ 451 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 452 error_f("tcgetattr: %s", strerror(errno)); 453 454 window = CHAN_SES_WINDOW_DEFAULT; 455 packetmax = CHAN_SES_PACKET_DEFAULT; 456 if (cctx->want_tty) { 457 window >>= 1; 458 packetmax >>= 1; 459 } 460 461 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 462 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 463 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO); 464 465 nc->ctl_chan = c->self; /* link session -> control channel */ 466 c->remote_id = nc->self; /* link control -> session channel */ 467 c->have_remote_id = 1; 468 469 if (cctx->want_tty && escape_char != 0xffffffff) { 470 channel_register_filter(ssh, nc->self, 471 client_simple_escape_filter, NULL, 472 client_filter_cleanup, 473 client_new_escape_filter_ctx((int)escape_char)); 474 } 475 476 debug2_f("channel_new: %d linked to control channel %d", 477 nc->self, nc->ctl_chan); 478 479 channel_send_open(ssh, nc->self); 480 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 481 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 482 channel_register_cleanup(ssh, nc->self, 483 mux_master_session_cleanup_cb, 1); 484 485 /* reply is deferred, sent by mux_session_confirm */ 486 return 0; 487 } 488 489 static int 490 mux_master_process_alive_check(struct ssh *ssh, u_int rid, 491 Channel *c, struct sshbuf *m, struct sshbuf *reply) 492 { 493 int r; 494 495 debug2_f("channel %d: alive check", c->self); 496 497 /* prepare reply */ 498 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 499 (r = sshbuf_put_u32(reply, rid)) != 0 || 500 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 501 fatal_fr(r, "reply"); 502 503 return 0; 504 } 505 506 static int 507 mux_master_process_terminate(struct ssh *ssh, u_int rid, 508 Channel *c, struct sshbuf *m, struct sshbuf *reply) 509 { 510 debug2_f("channel %d: terminate request", c->self); 511 512 if (options.control_master == SSHCTL_MASTER_ASK || 513 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 514 if (!ask_permission("Terminate shared connection to %s? ", 515 host)) { 516 debug2_f("termination refused by user"); 517 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 518 "Permission denied"); 519 return 0; 520 } 521 } 522 523 quit_pending = 1; 524 reply_ok(reply, rid); 525 /* XXX exit happens too soon - message never makes it to client */ 526 return 0; 527 } 528 529 static char * 530 format_forward(u_int ftype, struct Forward *fwd) 531 { 532 char *ret; 533 534 switch (ftype) { 535 case MUX_FWD_LOCAL: 536 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 537 (fwd->listen_path != NULL) ? fwd->listen_path : 538 (fwd->listen_host == NULL) ? 539 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 540 fwd->listen_host, fwd->listen_port, 541 (fwd->connect_path != NULL) ? fwd->connect_path : 542 fwd->connect_host, fwd->connect_port); 543 break; 544 case MUX_FWD_DYNAMIC: 545 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 546 (fwd->listen_host == NULL) ? 547 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 548 fwd->listen_host, fwd->listen_port); 549 break; 550 case MUX_FWD_REMOTE: 551 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 552 (fwd->listen_path != NULL) ? fwd->listen_path : 553 (fwd->listen_host == NULL) ? 554 "LOCALHOST" : fwd->listen_host, 555 fwd->listen_port, 556 (fwd->connect_path != NULL) ? fwd->connect_path : 557 fwd->connect_host, fwd->connect_port); 558 break; 559 default: 560 fatal_f("unknown forward type %u", ftype); 561 } 562 return ret; 563 } 564 565 static int 566 compare_host(const char *a, const char *b) 567 { 568 if (a == NULL && b == NULL) 569 return 1; 570 if (a == NULL || b == NULL) 571 return 0; 572 return strcmp(a, b) == 0; 573 } 574 575 static int 576 compare_forward(struct Forward *a, struct Forward *b) 577 { 578 if (!compare_host(a->listen_host, b->listen_host)) 579 return 0; 580 if (!compare_host(a->listen_path, b->listen_path)) 581 return 0; 582 if (a->listen_port != b->listen_port) 583 return 0; 584 if (!compare_host(a->connect_host, b->connect_host)) 585 return 0; 586 if (!compare_host(a->connect_path, b->connect_path)) 587 return 0; 588 if (a->connect_port != b->connect_port) 589 return 0; 590 591 return 1; 592 } 593 594 static void 595 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 596 { 597 struct mux_channel_confirm_ctx *fctx = ctxt; 598 char *failmsg = NULL; 599 struct Forward *rfwd; 600 Channel *c; 601 struct sshbuf *out; 602 u_int port; 603 int r; 604 605 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 606 /* no channel for reply */ 607 error_f("unknown channel"); 608 return; 609 } 610 if ((out = sshbuf_new()) == NULL) 611 fatal_f("sshbuf_new"); 612 if (fctx->fid >= options.num_remote_forwards || 613 (options.remote_forwards[fctx->fid].connect_path == NULL && 614 options.remote_forwards[fctx->fid].connect_host == NULL)) { 615 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 616 goto fail; 617 } 618 rfwd = &options.remote_forwards[fctx->fid]; 619 debug_f("%s for: listen %d, connect %s:%d", 620 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 621 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 622 rfwd->connect_host, rfwd->connect_port); 623 if (type == SSH2_MSG_REQUEST_SUCCESS) { 624 if (rfwd->listen_port == 0) { 625 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 626 fatal_fr(r, "parse port"); 627 if (port > 65535) { 628 fatal("Invalid allocated port %u for " 629 "mux remote forward to %s:%d", port, 630 rfwd->connect_host, rfwd->connect_port); 631 } 632 rfwd->allocated_port = (int)port; 633 debug("Allocated port %u for mux remote forward" 634 " to %s:%d", rfwd->allocated_port, 635 rfwd->connect_host, rfwd->connect_port); 636 if ((r = sshbuf_put_u32(out, 637 MUX_S_REMOTE_PORT)) != 0 || 638 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 639 (r = sshbuf_put_u32(out, 640 rfwd->allocated_port)) != 0) 641 fatal_fr(r, "reply"); 642 channel_update_permission(ssh, rfwd->handle, 643 rfwd->allocated_port); 644 } else { 645 reply_ok(out, fctx->rid); 646 } 647 goto out; 648 } else { 649 if (rfwd->listen_port == 0) 650 channel_update_permission(ssh, rfwd->handle, -1); 651 if (rfwd->listen_path != NULL) 652 xasprintf(&failmsg, "remote port forwarding failed for " 653 "listen path %s", rfwd->listen_path); 654 else 655 xasprintf(&failmsg, "remote port forwarding failed for " 656 "listen port %d", rfwd->listen_port); 657 658 debug2_f("clearing registered forwarding for listen %d, " 659 "connect %s:%d", rfwd->listen_port, 660 rfwd->connect_path ? rfwd->connect_path : 661 rfwd->connect_host, rfwd->connect_port); 662 663 free(rfwd->listen_host); 664 free(rfwd->listen_path); 665 free(rfwd->connect_host); 666 free(rfwd->connect_path); 667 memset(rfwd, 0, sizeof(*rfwd)); 668 } 669 fail: 670 error_f("%s", failmsg); 671 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 672 free(failmsg); 673 out: 674 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 675 fatal_fr(r, "enqueue"); 676 sshbuf_free(out); 677 if (c->mux_pause <= 0) 678 fatal_f("mux_pause %d", c->mux_pause); 679 c->mux_pause = 0; /* start processing messages again */ 680 } 681 682 static int 683 mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 684 Channel *c, struct sshbuf *m, struct sshbuf *reply) 685 { 686 struct Forward fwd; 687 char *fwd_desc = NULL; 688 char *listen_addr, *connect_addr; 689 u_int ftype; 690 u_int lport, cport; 691 int r, i, ret = 0, freefwd = 1; 692 693 memset(&fwd, 0, sizeof(fwd)); 694 695 /* XXX - lport/cport check redundant */ 696 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 697 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 698 (r = sshbuf_get_u32(m, &lport)) != 0 || 699 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 700 (r = sshbuf_get_u32(m, &cport)) != 0 || 701 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 702 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 703 error_f("malformed message"); 704 ret = -1; 705 goto out; 706 } 707 if (*listen_addr == '\0') { 708 free(listen_addr); 709 listen_addr = NULL; 710 } 711 if (*connect_addr == '\0') { 712 free(connect_addr); 713 connect_addr = NULL; 714 } 715 716 memset(&fwd, 0, sizeof(fwd)); 717 fwd.listen_port = lport; 718 if (fwd.listen_port == PORT_STREAMLOCAL) 719 fwd.listen_path = listen_addr; 720 else 721 fwd.listen_host = listen_addr; 722 fwd.connect_port = cport; 723 if (fwd.connect_port == PORT_STREAMLOCAL) 724 fwd.connect_path = connect_addr; 725 else 726 fwd.connect_host = connect_addr; 727 728 debug2_f("channel %d: request %s", c->self, 729 (fwd_desc = format_forward(ftype, &fwd))); 730 731 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 732 ftype != MUX_FWD_DYNAMIC) { 733 logit_f("invalid forwarding type %u", ftype); 734 invalid: 735 free(listen_addr); 736 free(connect_addr); 737 reply_error(reply, MUX_S_FAILURE, rid, 738 "Invalid forwarding request"); 739 return 0; 740 } 741 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 742 logit_f("streamlocal and dynamic forwards " 743 "are mutually exclusive"); 744 goto invalid; 745 } 746 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 747 logit_f("invalid listen port %u", fwd.listen_port); 748 goto invalid; 749 } 750 if ((fwd.connect_port != PORT_STREAMLOCAL && 751 fwd.connect_port >= 65536) || 752 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 753 fwd.connect_port == 0)) { 754 logit_f("invalid connect port %u", 755 fwd.connect_port); 756 goto invalid; 757 } 758 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 759 fwd.connect_path == NULL) { 760 logit_f("missing connect host"); 761 goto invalid; 762 } 763 764 /* Skip forwards that have already been requested */ 765 switch (ftype) { 766 case MUX_FWD_LOCAL: 767 case MUX_FWD_DYNAMIC: 768 for (i = 0; i < options.num_local_forwards; i++) { 769 if (compare_forward(&fwd, 770 options.local_forwards + i)) { 771 exists: 772 debug2_f("found existing forwarding"); 773 reply_ok(reply, rid); 774 goto out; 775 } 776 } 777 break; 778 case MUX_FWD_REMOTE: 779 for (i = 0; i < options.num_remote_forwards; i++) { 780 if (!compare_forward(&fwd, options.remote_forwards + i)) 781 continue; 782 if (fwd.listen_port != 0) 783 goto exists; 784 debug2_f("found allocated port"); 785 if ((r = sshbuf_put_u32(reply, 786 MUX_S_REMOTE_PORT)) != 0 || 787 (r = sshbuf_put_u32(reply, rid)) != 0 || 788 (r = sshbuf_put_u32(reply, 789 options.remote_forwards[i].allocated_port)) != 0) 790 fatal_fr(r, "reply FWD_REMOTE"); 791 goto out; 792 } 793 break; 794 } 795 796 if (options.control_master == SSHCTL_MASTER_ASK || 797 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 798 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 799 debug2_f("forwarding refused by user"); 800 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 801 "Permission denied"); 802 goto out; 803 } 804 } 805 806 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 807 if (!channel_setup_local_fwd_listener(ssh, &fwd, 808 &options.fwd_opts)) { 809 fail: 810 logit_f("requested %s failed", fwd_desc); 811 reply_error(reply, MUX_S_FAILURE, rid, 812 "Port forwarding failed"); 813 goto out; 814 } 815 add_local_forward(&options, &fwd); 816 freefwd = 0; 817 } else { 818 struct mux_channel_confirm_ctx *fctx; 819 820 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 821 if (fwd.handle < 0) 822 goto fail; 823 add_remote_forward(&options, &fwd); 824 fctx = xcalloc(1, sizeof(*fctx)); 825 fctx->cid = c->self; 826 fctx->rid = rid; 827 fctx->fid = options.num_remote_forwards - 1; 828 client_register_global_confirm(mux_confirm_remote_forward, 829 fctx); 830 freefwd = 0; 831 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 832 /* delayed reply in mux_confirm_remote_forward */ 833 goto out; 834 } 835 reply_ok(reply, rid); 836 out: 837 free(fwd_desc); 838 if (freefwd) { 839 free(fwd.listen_host); 840 free(fwd.listen_path); 841 free(fwd.connect_host); 842 free(fwd.connect_path); 843 } 844 return ret; 845 } 846 847 static int 848 mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 849 Channel *c, struct sshbuf *m, struct sshbuf *reply) 850 { 851 struct Forward fwd, *found_fwd; 852 char *fwd_desc = NULL; 853 const char *error_reason = NULL; 854 char *listen_addr = NULL, *connect_addr = NULL; 855 u_int ftype; 856 int r, i, ret = 0; 857 u_int lport, cport; 858 859 memset(&fwd, 0, sizeof(fwd)); 860 861 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 862 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 863 (r = sshbuf_get_u32(m, &lport)) != 0 || 864 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 865 (r = sshbuf_get_u32(m, &cport)) != 0 || 866 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 867 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 868 error_f("malformed message"); 869 ret = -1; 870 goto out; 871 } 872 873 if (*listen_addr == '\0') { 874 free(listen_addr); 875 listen_addr = NULL; 876 } 877 if (*connect_addr == '\0') { 878 free(connect_addr); 879 connect_addr = NULL; 880 } 881 882 memset(&fwd, 0, sizeof(fwd)); 883 fwd.listen_port = lport; 884 if (fwd.listen_port == PORT_STREAMLOCAL) 885 fwd.listen_path = listen_addr; 886 else 887 fwd.listen_host = listen_addr; 888 fwd.connect_port = cport; 889 if (fwd.connect_port == PORT_STREAMLOCAL) 890 fwd.connect_path = connect_addr; 891 else 892 fwd.connect_host = connect_addr; 893 894 debug2_f("channel %d: request cancel %s", c->self, 895 (fwd_desc = format_forward(ftype, &fwd))); 896 897 /* make sure this has been requested */ 898 found_fwd = NULL; 899 switch (ftype) { 900 case MUX_FWD_LOCAL: 901 case MUX_FWD_DYNAMIC: 902 for (i = 0; i < options.num_local_forwards; i++) { 903 if (compare_forward(&fwd, 904 options.local_forwards + i)) { 905 found_fwd = options.local_forwards + i; 906 break; 907 } 908 } 909 break; 910 case MUX_FWD_REMOTE: 911 for (i = 0; i < options.num_remote_forwards; i++) { 912 if (compare_forward(&fwd, 913 options.remote_forwards + i)) { 914 found_fwd = options.remote_forwards + i; 915 break; 916 } 917 } 918 break; 919 } 920 921 if (found_fwd == NULL) 922 error_reason = "port not forwarded"; 923 else if (ftype == MUX_FWD_REMOTE) { 924 /* 925 * This shouldn't fail unless we confused the host/port 926 * between options.remote_forwards and permitted_opens. 927 * However, for dynamic allocated listen ports we need 928 * to use the actual listen port. 929 */ 930 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 931 error_reason = "port not in permitted opens"; 932 } else { /* local and dynamic forwards */ 933 /* Ditto */ 934 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 935 &options.fwd_opts) == -1) 936 error_reason = "port not found"; 937 } 938 939 if (error_reason != NULL) 940 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 941 else { 942 reply_ok(reply, rid); 943 free(found_fwd->listen_host); 944 free(found_fwd->listen_path); 945 free(found_fwd->connect_host); 946 free(found_fwd->connect_path); 947 found_fwd->listen_host = found_fwd->connect_host = NULL; 948 found_fwd->listen_path = found_fwd->connect_path = NULL; 949 found_fwd->listen_port = found_fwd->connect_port = 0; 950 } 951 out: 952 free(fwd_desc); 953 free(listen_addr); 954 free(connect_addr); 955 956 return ret; 957 } 958 959 static int 960 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 961 Channel *c, struct sshbuf *m, struct sshbuf *reply) 962 { 963 Channel *nc; 964 char *chost = NULL; 965 u_int cport, i, j; 966 int r, new_fd[2]; 967 struct mux_stdio_confirm_ctx *cctx; 968 969 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 970 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 971 (r = sshbuf_get_u32(m, &cport)) != 0) { 972 free(chost); 973 error_f("malformed message"); 974 return -1; 975 } 976 977 debug2_f("channel %d: stdio fwd to %s:%u", c->self, chost, cport); 978 979 /* Gather fds from client */ 980 for(i = 0; i < 2; i++) { 981 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 982 error_f("failed to receive fd %d from client", i); 983 for (j = 0; j < i; j++) 984 close(new_fd[j]); 985 free(chost); 986 987 /* prepare reply */ 988 reply_error(reply, MUX_S_FAILURE, rid, 989 "did not receive file descriptors"); 990 return -1; 991 } 992 } 993 994 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 995 996 /* XXX support multiple child sessions in future */ 997 if (c->have_remote_id) { 998 debug2_f("session already open"); 999 reply_error(reply, MUX_S_FAILURE, rid, 1000 "Multiple sessions not supported"); 1001 cleanup: 1002 close(new_fd[0]); 1003 close(new_fd[1]); 1004 free(chost); 1005 return 0; 1006 } 1007 1008 if (options.control_master == SSHCTL_MASTER_ASK || 1009 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1010 if (!ask_permission("Allow forward to %s:%u? ", 1011 chost, cport)) { 1012 debug2_f("stdio fwd refused by user"); 1013 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1014 "Permission denied"); 1015 goto cleanup; 1016 } 1017 } 1018 1019 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1], 1020 CHANNEL_NONBLOCK_STDIO); 1021 free(chost); 1022 1023 nc->ctl_chan = c->self; /* link session -> control channel */ 1024 c->remote_id = nc->self; /* link control -> session channel */ 1025 c->have_remote_id = 1; 1026 1027 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan); 1028 1029 channel_register_cleanup(ssh, nc->self, 1030 mux_master_session_cleanup_cb, 1); 1031 1032 cctx = xcalloc(1, sizeof(*cctx)); 1033 cctx->rid = rid; 1034 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1035 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1036 1037 /* reply is deferred, sent by mux_session_confirm */ 1038 return 0; 1039 } 1040 1041 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1042 static void 1043 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1044 { 1045 struct mux_stdio_confirm_ctx *cctx = arg; 1046 Channel *c, *cc; 1047 struct sshbuf *reply; 1048 int r; 1049 1050 if (cctx == NULL) 1051 fatal_f("cctx == NULL"); 1052 if ((c = channel_by_id(ssh, id)) == NULL) 1053 fatal_f("no channel for id %d", id); 1054 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1055 fatal_f("channel %d lacks control channel %d", 1056 id, c->ctl_chan); 1057 if ((reply = sshbuf_new()) == NULL) 1058 fatal_f("sshbuf_new"); 1059 1060 if (!success) { 1061 debug3_f("sending failure reply"); 1062 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1063 "Session open refused by peer"); 1064 /* prepare reply */ 1065 goto done; 1066 } 1067 1068 debug3_f("sending success reply"); 1069 /* prepare reply */ 1070 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1071 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1072 (r = sshbuf_put_u32(reply, c->self)) != 0) 1073 fatal_fr(r, "reply"); 1074 1075 done: 1076 /* Send reply */ 1077 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1078 fatal_fr(r, "enqueue"); 1079 sshbuf_free(reply); 1080 1081 if (cc->mux_pause <= 0) 1082 fatal_f("mux_pause %d", cc->mux_pause); 1083 cc->mux_pause = 0; /* start processing messages again */ 1084 c->open_confirm_ctx = NULL; 1085 free(cctx); 1086 } 1087 1088 static int 1089 mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1090 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1091 { 1092 debug_f("channel %d: stop listening", c->self); 1093 1094 if (options.control_master == SSHCTL_MASTER_ASK || 1095 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1096 if (!ask_permission("Disable further multiplexing on shared " 1097 "connection to %s? ", host)) { 1098 debug2_f("stop listen refused by user"); 1099 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1100 "Permission denied"); 1101 return 0; 1102 } 1103 } 1104 1105 if (mux_listener_channel != NULL) { 1106 channel_free(ssh, mux_listener_channel); 1107 client_stop_mux(); 1108 free(options.control_path); 1109 options.control_path = NULL; 1110 mux_listener_channel = NULL; 1111 muxserver_sock = -1; 1112 } 1113 1114 reply_ok(reply, rid); 1115 return 0; 1116 } 1117 1118 static int 1119 mux_master_process_proxy(struct ssh *ssh, u_int rid, 1120 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1121 { 1122 int r; 1123 1124 debug_f("channel %d: proxy request", c->self); 1125 1126 c->mux_rcb = channel_proxy_downstream; 1127 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1128 (r = sshbuf_put_u32(reply, rid)) != 0) 1129 fatal_fr(r, "reply"); 1130 1131 return 0; 1132 } 1133 1134 /* Channel callbacks fired on read/write from mux client fd */ 1135 static int 1136 mux_master_read_cb(struct ssh *ssh, Channel *c) 1137 { 1138 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1139 struct sshbuf *in = NULL, *out = NULL; 1140 u_int type, rid, i; 1141 int r, ret = -1; 1142 1143 if ((out = sshbuf_new()) == NULL) 1144 fatal_f("sshbuf_new"); 1145 1146 /* Setup ctx and */ 1147 if (c->mux_ctx == NULL) { 1148 state = xcalloc(1, sizeof(*state)); 1149 c->mux_ctx = state; 1150 channel_register_cleanup(ssh, c->self, 1151 mux_master_control_cleanup_cb, 0); 1152 1153 /* Send hello */ 1154 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1155 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1156 fatal_fr(r, "reply"); 1157 /* no extensions */ 1158 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1159 fatal_fr(r, "enqueue"); 1160 debug3_f("channel %d: hello sent", c->self); 1161 ret = 0; 1162 goto out; 1163 } 1164 1165 /* Channel code ensures that we receive whole packets */ 1166 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1167 malf: 1168 error_f("malformed message"); 1169 goto out; 1170 } 1171 1172 if ((r = sshbuf_get_u32(in, &type)) != 0) 1173 goto malf; 1174 debug3_f("channel %d packet type 0x%08x len %zu", c->self, 1175 type, sshbuf_len(in)); 1176 1177 if (type == MUX_MSG_HELLO) 1178 rid = 0; 1179 else { 1180 if (!state->hello_rcvd) { 1181 error_f("expected MUX_MSG_HELLO(0x%08x), " 1182 "received 0x%08x", MUX_MSG_HELLO, type); 1183 goto out; 1184 } 1185 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1186 goto malf; 1187 } 1188 1189 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1190 if (type == mux_master_handlers[i].type) { 1191 ret = mux_master_handlers[i].handler(ssh, rid, 1192 c, in, out); 1193 break; 1194 } 1195 } 1196 if (mux_master_handlers[i].handler == NULL) { 1197 error_f("unsupported mux message 0x%08x", type); 1198 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1199 ret = 0; 1200 } 1201 /* Enqueue reply packet */ 1202 if (sshbuf_len(out) != 0 && 1203 (r = sshbuf_put_stringb(c->output, out)) != 0) 1204 fatal_fr(r, "enqueue"); 1205 out: 1206 sshbuf_free(in); 1207 sshbuf_free(out); 1208 return ret; 1209 } 1210 1211 void 1212 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1213 { 1214 struct sshbuf *m; 1215 Channel *mux_chan; 1216 int r; 1217 1218 debug3_f("channel %d: exit message, exitval %d", c->self, exitval); 1219 1220 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1221 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1222 1223 /* Append exit message packet to control socket output queue */ 1224 if ((m = sshbuf_new()) == NULL) 1225 fatal_f("sshbuf_new"); 1226 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1227 (r = sshbuf_put_u32(m, c->self)) != 0 || 1228 (r = sshbuf_put_u32(m, exitval)) != 0 || 1229 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1230 fatal_fr(r, "reply"); 1231 sshbuf_free(m); 1232 } 1233 1234 void 1235 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1236 { 1237 struct sshbuf *m; 1238 Channel *mux_chan; 1239 int r; 1240 1241 debug3_f("channel %d: TTY alloc failed", c->self); 1242 1243 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1244 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1245 1246 /* Append exit message packet to control socket output queue */ 1247 if ((m = sshbuf_new()) == NULL) 1248 fatal_f("sshbuf_new"); 1249 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1250 (r = sshbuf_put_u32(m, c->self)) != 0 || 1251 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1252 fatal_fr(r, "reply"); 1253 sshbuf_free(m); 1254 } 1255 1256 /* Prepare a mux master to listen on a Unix domain socket. */ 1257 void 1258 muxserver_listen(struct ssh *ssh) 1259 { 1260 mode_t old_umask; 1261 char *orig_control_path = options.control_path; 1262 char rbuf[16+1]; 1263 u_int i, r; 1264 int oerrno; 1265 1266 if (options.control_path == NULL || 1267 options.control_master == SSHCTL_MASTER_NO) 1268 return; 1269 1270 debug("setting up multiplex master socket"); 1271 1272 /* 1273 * Use a temporary path before listen so we can pseudo-atomically 1274 * establish the listening socket in its final location to avoid 1275 * other processes racing in between bind() and listen() and hitting 1276 * an unready socket. 1277 */ 1278 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1279 r = arc4random_uniform(26+26+10); 1280 rbuf[i] = (r < 26) ? 'a' + r : 1281 (r < 26*2) ? 'A' + r - 26 : 1282 '0' + r - 26 - 26; 1283 } 1284 rbuf[sizeof(rbuf) - 1] = '\0'; 1285 options.control_path = NULL; 1286 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1287 debug3_f("temporary control path %s", options.control_path); 1288 1289 old_umask = umask(0177); 1290 muxserver_sock = unix_listener(options.control_path, 64, 0); 1291 oerrno = errno; 1292 umask(old_umask); 1293 if (muxserver_sock < 0) { 1294 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1295 error("ControlSocket %s already exists, " 1296 "disabling multiplexing", options.control_path); 1297 disable_mux_master: 1298 if (muxserver_sock != -1) { 1299 close(muxserver_sock); 1300 muxserver_sock = -1; 1301 } 1302 free(orig_control_path); 1303 free(options.control_path); 1304 options.control_path = NULL; 1305 options.control_master = SSHCTL_MASTER_NO; 1306 return; 1307 } else { 1308 /* unix_listener() logs the error */ 1309 cleanup_exit(255); 1310 } 1311 } 1312 1313 /* Now atomically "move" the mux socket into position */ 1314 if (link(options.control_path, orig_control_path) != 0) { 1315 if (errno != EEXIST) { 1316 fatal_f("link mux listener %s => %s: %s", 1317 options.control_path, orig_control_path, 1318 strerror(errno)); 1319 } 1320 error("ControlSocket %s already exists, disabling multiplexing", 1321 orig_control_path); 1322 unlink(options.control_path); 1323 goto disable_mux_master; 1324 } 1325 unlink(options.control_path); 1326 free(options.control_path); 1327 options.control_path = orig_control_path; 1328 1329 set_nonblock(muxserver_sock); 1330 1331 mux_listener_channel = channel_new(ssh, "mux listener", 1332 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1333 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1334 0, options.control_path, 1); 1335 mux_listener_channel->mux_rcb = mux_master_read_cb; 1336 debug3_f("mux listener channel %d fd %d", 1337 mux_listener_channel->self, mux_listener_channel->sock); 1338 } 1339 1340 /* Callback on open confirmation in mux master for a mux client session. */ 1341 static void 1342 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1343 { 1344 struct mux_session_confirm_ctx *cctx = arg; 1345 const char *display; 1346 Channel *c, *cc; 1347 int i, r; 1348 struct sshbuf *reply; 1349 1350 if (cctx == NULL) 1351 fatal_f("cctx == NULL"); 1352 if ((c = channel_by_id(ssh, id)) == NULL) 1353 fatal_f("no channel for id %d", id); 1354 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1355 fatal_f("channel %d lacks control channel %d", 1356 id, c->ctl_chan); 1357 if ((reply = sshbuf_new()) == NULL) 1358 fatal_f("sshbuf_new"); 1359 1360 if (!success) { 1361 debug3_f("sending failure reply"); 1362 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1363 "Session open refused by peer"); 1364 goto done; 1365 } 1366 1367 display = getenv("DISPLAY"); 1368 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1369 char *proto, *data; 1370 1371 /* Get reasonable local authentication information. */ 1372 if (client_x11_get_proto(ssh, display, options.xauth_location, 1373 options.forward_x11_trusted, options.forward_x11_timeout, 1374 &proto, &data) == 0) { 1375 /* Request forwarding with authentication spoofing. */ 1376 debug("Requesting X11 forwarding with authentication " 1377 "spoofing."); 1378 x11_request_forwarding_with_spoofing(ssh, id, 1379 display, proto, data, 1); 1380 /* XXX exit_on_forward_failure */ 1381 client_expect_confirm(ssh, id, "X11 forwarding", 1382 CONFIRM_WARN); 1383 } 1384 } 1385 1386 if (cctx->want_agent_fwd && options.forward_agent) { 1387 debug("Requesting authentication agent forwarding."); 1388 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1389 if ((r = sshpkt_send(ssh)) != 0) 1390 fatal_fr(r, "send"); 1391 } 1392 1393 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1394 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1395 1396 debug3_f("sending success reply"); 1397 /* prepare reply */ 1398 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1399 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1400 (r = sshbuf_put_u32(reply, c->self)) != 0) 1401 fatal_fr(r, "reply"); 1402 1403 done: 1404 /* Send reply */ 1405 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1406 fatal_fr(r, "enqueue"); 1407 sshbuf_free(reply); 1408 1409 if (cc->mux_pause <= 0) 1410 fatal_f("mux_pause %d", cc->mux_pause); 1411 cc->mux_pause = 0; /* start processing messages again */ 1412 c->open_confirm_ctx = NULL; 1413 sshbuf_free(cctx->cmd); 1414 free(cctx->term); 1415 if (cctx->env != NULL) { 1416 for (i = 0; cctx->env[i] != NULL; i++) 1417 free(cctx->env[i]); 1418 free(cctx->env); 1419 } 1420 free(cctx); 1421 } 1422 1423 /* ** Multiplexing client support */ 1424 1425 /* Exit signal handler */ 1426 static void 1427 control_client_sighandler(int signo) 1428 { 1429 muxclient_terminate = signo; 1430 } 1431 1432 /* 1433 * Relay signal handler - used to pass some signals from mux client to 1434 * mux master. 1435 */ 1436 static void 1437 control_client_sigrelay(int signo) 1438 { 1439 int save_errno = errno; 1440 1441 if (muxserver_pid > 1) 1442 kill(muxserver_pid, signo); 1443 1444 errno = save_errno; 1445 } 1446 1447 static int 1448 mux_client_read(int fd, struct sshbuf *b, size_t need) 1449 { 1450 size_t have; 1451 ssize_t len; 1452 u_char *p; 1453 struct pollfd pfd; 1454 int r; 1455 1456 pfd.fd = fd; 1457 pfd.events = POLLIN; 1458 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1459 fatal_fr(r, "reserve"); 1460 for (have = 0; have < need; ) { 1461 if (muxclient_terminate) { 1462 errno = EINTR; 1463 return -1; 1464 } 1465 len = read(fd, p + have, need - have); 1466 if (len == -1) { 1467 switch (errno) { 1468 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1469 case EWOULDBLOCK: 1470 #endif 1471 case EAGAIN: 1472 (void)poll(&pfd, 1, -1); 1473 /* FALLTHROUGH */ 1474 case EINTR: 1475 continue; 1476 default: 1477 return -1; 1478 } 1479 } 1480 if (len == 0) { 1481 errno = EPIPE; 1482 return -1; 1483 } 1484 have += (size_t)len; 1485 } 1486 return 0; 1487 } 1488 1489 static int 1490 mux_client_write_packet(int fd, struct sshbuf *m) 1491 { 1492 struct sshbuf *queue; 1493 u_int have, need; 1494 int r, oerrno, len; 1495 const u_char *ptr; 1496 struct pollfd pfd; 1497 1498 pfd.fd = fd; 1499 pfd.events = POLLOUT; 1500 if ((queue = sshbuf_new()) == NULL) 1501 fatal_f("sshbuf_new"); 1502 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1503 fatal_fr(r, "enqueue"); 1504 1505 need = sshbuf_len(queue); 1506 ptr = sshbuf_ptr(queue); 1507 1508 for (have = 0; have < need; ) { 1509 if (muxclient_terminate) { 1510 sshbuf_free(queue); 1511 errno = EINTR; 1512 return -1; 1513 } 1514 len = write(fd, ptr + have, need - have); 1515 if (len == -1) { 1516 switch (errno) { 1517 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1518 case EWOULDBLOCK: 1519 #endif 1520 case EAGAIN: 1521 (void)poll(&pfd, 1, -1); 1522 /* FALLTHROUGH */ 1523 case EINTR: 1524 continue; 1525 default: 1526 oerrno = errno; 1527 sshbuf_free(queue); 1528 errno = oerrno; 1529 return -1; 1530 } 1531 } 1532 if (len == 0) { 1533 sshbuf_free(queue); 1534 errno = EPIPE; 1535 return -1; 1536 } 1537 have += (u_int)len; 1538 } 1539 sshbuf_free(queue); 1540 return 0; 1541 } 1542 1543 static int 1544 mux_client_read_packet(int fd, struct sshbuf *m) 1545 { 1546 struct sshbuf *queue; 1547 size_t need, have; 1548 const u_char *ptr; 1549 int r, oerrno; 1550 1551 if ((queue = sshbuf_new()) == NULL) 1552 fatal_f("sshbuf_new"); 1553 if (mux_client_read(fd, queue, 4) != 0) { 1554 if ((oerrno = errno) == EPIPE) 1555 debug3_f("read header failed: %s", 1556 strerror(errno)); 1557 sshbuf_free(queue); 1558 errno = oerrno; 1559 return -1; 1560 } 1561 need = PEEK_U32(sshbuf_ptr(queue)); 1562 if (mux_client_read(fd, queue, need) != 0) { 1563 oerrno = errno; 1564 debug3_f("read body failed: %s", strerror(errno)); 1565 sshbuf_free(queue); 1566 errno = oerrno; 1567 return -1; 1568 } 1569 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1570 (r = sshbuf_put(m, ptr, have)) != 0) 1571 fatal_fr(r, "dequeue"); 1572 sshbuf_free(queue); 1573 return 0; 1574 } 1575 1576 static int 1577 mux_client_hello_exchange(int fd) 1578 { 1579 struct sshbuf *m; 1580 u_int type, ver; 1581 int r, ret = -1; 1582 1583 if ((m = sshbuf_new()) == NULL) 1584 fatal_f("sshbuf_new"); 1585 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1586 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1587 fatal_fr(r, "assemble hello"); 1588 /* no extensions */ 1589 1590 if (mux_client_write_packet(fd, m) != 0) { 1591 debug_f("write packet: %s", strerror(errno)); 1592 goto out; 1593 } 1594 1595 sshbuf_reset(m); 1596 1597 /* Read their HELLO */ 1598 if (mux_client_read_packet(fd, m) != 0) { 1599 debug_f("read packet failed"); 1600 goto out; 1601 } 1602 1603 if ((r = sshbuf_get_u32(m, &type)) != 0) 1604 fatal_fr(r, "parse type"); 1605 if (type != MUX_MSG_HELLO) { 1606 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1607 goto out; 1608 } 1609 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1610 fatal_fr(r, "parse version"); 1611 if (ver != SSHMUX_VER) { 1612 error("Unsupported multiplexing protocol version %d " 1613 "(expected %d)", ver, SSHMUX_VER); 1614 goto out; 1615 } 1616 debug2_f("master version %u", ver); 1617 /* No extensions are presently defined */ 1618 while (sshbuf_len(m) > 0) { 1619 char *name = NULL; 1620 1621 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1622 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1623 error_fr(r, "parse extension"); 1624 goto out; 1625 } 1626 debug2("Unrecognised master extension \"%s\"", name); 1627 free(name); 1628 } 1629 /* success */ 1630 ret = 0; 1631 out: 1632 sshbuf_free(m); 1633 return ret; 1634 } 1635 1636 static u_int 1637 mux_client_request_alive(int fd) 1638 { 1639 struct sshbuf *m; 1640 char *e; 1641 u_int pid, type, rid; 1642 int r; 1643 1644 debug3_f("entering"); 1645 1646 if ((m = sshbuf_new()) == NULL) 1647 fatal_f("sshbuf_new"); 1648 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1649 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1650 fatal_fr(r, "assemble"); 1651 1652 if (mux_client_write_packet(fd, m) != 0) 1653 fatal_f("write packet: %s", strerror(errno)); 1654 1655 sshbuf_reset(m); 1656 1657 /* Read their reply */ 1658 if (mux_client_read_packet(fd, m) != 0) { 1659 sshbuf_free(m); 1660 return 0; 1661 } 1662 1663 if ((r = sshbuf_get_u32(m, &type)) != 0) 1664 fatal_fr(r, "parse type"); 1665 if (type != MUX_S_ALIVE) { 1666 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1667 fatal_fr(r, "parse error message"); 1668 fatal_f("master returned error: %s", e); 1669 } 1670 1671 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1672 fatal_fr(r, "parse remote ID"); 1673 if (rid != muxclient_request_id) 1674 fatal_f("out of sequence reply: my id %u theirs %u", 1675 muxclient_request_id, rid); 1676 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1677 fatal_fr(r, "parse PID"); 1678 sshbuf_free(m); 1679 1680 debug3_f("done pid = %u", pid); 1681 1682 muxclient_request_id++; 1683 1684 return pid; 1685 } 1686 1687 static void 1688 mux_client_request_terminate(int fd) 1689 { 1690 struct sshbuf *m; 1691 char *e; 1692 u_int type, rid; 1693 int r; 1694 1695 debug3_f("entering"); 1696 1697 if ((m = sshbuf_new()) == NULL) 1698 fatal_f("sshbuf_new"); 1699 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1700 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1701 fatal_fr(r, "request"); 1702 1703 if (mux_client_write_packet(fd, m) != 0) 1704 fatal_f("write packet: %s", strerror(errno)); 1705 1706 sshbuf_reset(m); 1707 1708 /* Read their reply */ 1709 if (mux_client_read_packet(fd, m) != 0) { 1710 /* Remote end exited already */ 1711 if (errno == EPIPE) { 1712 sshbuf_free(m); 1713 return; 1714 } 1715 fatal_f("read from master failed: %s", strerror(errno)); 1716 } 1717 1718 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1719 (r = sshbuf_get_u32(m, &rid)) != 0) 1720 fatal_fr(r, "parse"); 1721 if (rid != muxclient_request_id) 1722 fatal_f("out of sequence reply: my id %u theirs %u", 1723 muxclient_request_id, rid); 1724 switch (type) { 1725 case MUX_S_OK: 1726 break; 1727 case MUX_S_PERMISSION_DENIED: 1728 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1729 fatal_fr(r, "parse error message"); 1730 fatal("Master refused termination request: %s", e); 1731 case MUX_S_FAILURE: 1732 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1733 fatal_fr(r, "parse error message"); 1734 fatal_f("termination request failed: %s", e); 1735 default: 1736 fatal_f("unexpected response from master 0x%08x", type); 1737 } 1738 sshbuf_free(m); 1739 muxclient_request_id++; 1740 } 1741 1742 static int 1743 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1744 { 1745 struct sshbuf *m; 1746 char *e, *fwd_desc; 1747 const char *lhost, *chost; 1748 u_int type, rid; 1749 int r; 1750 1751 fwd_desc = format_forward(ftype, fwd); 1752 debug("Requesting %s %s", 1753 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1754 free(fwd_desc); 1755 1756 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1757 if (fwd->listen_path != NULL) 1758 lhost = fwd->listen_path; 1759 else if (fwd->listen_host == NULL) 1760 lhost = ""; 1761 else if (*fwd->listen_host == '\0') 1762 lhost = "*"; 1763 else 1764 lhost = fwd->listen_host; 1765 1766 if (fwd->connect_path != NULL) 1767 chost = fwd->connect_path; 1768 else if (fwd->connect_host == NULL) 1769 chost = ""; 1770 else 1771 chost = fwd->connect_host; 1772 1773 if ((m = sshbuf_new()) == NULL) 1774 fatal_f("sshbuf_new"); 1775 if ((r = sshbuf_put_u32(m, type)) != 0 || 1776 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1777 (r = sshbuf_put_u32(m, ftype)) != 0 || 1778 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1779 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1780 (r = sshbuf_put_cstring(m, chost)) != 0 || 1781 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1782 fatal_fr(r, "request"); 1783 1784 if (mux_client_write_packet(fd, m) != 0) 1785 fatal_f("write packet: %s", strerror(errno)); 1786 1787 sshbuf_reset(m); 1788 1789 /* Read their reply */ 1790 if (mux_client_read_packet(fd, m) != 0) { 1791 sshbuf_free(m); 1792 return -1; 1793 } 1794 1795 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1796 (r = sshbuf_get_u32(m, &rid)) != 0) 1797 fatal_fr(r, "parse"); 1798 if (rid != muxclient_request_id) 1799 fatal_f("out of sequence reply: my id %u theirs %u", 1800 muxclient_request_id, rid); 1801 1802 switch (type) { 1803 case MUX_S_OK: 1804 break; 1805 case MUX_S_REMOTE_PORT: 1806 if (cancel_flag) 1807 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1808 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1809 fatal_fr(r, "parse port"); 1810 verbose("Allocated port %u for remote forward to %s:%d", 1811 fwd->allocated_port, 1812 fwd->connect_host ? fwd->connect_host : "", 1813 fwd->connect_port); 1814 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1815 fprintf(stdout, "%i\n", fwd->allocated_port); 1816 break; 1817 case MUX_S_PERMISSION_DENIED: 1818 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1819 fatal_fr(r, "parse error message"); 1820 sshbuf_free(m); 1821 error("Master refused forwarding request: %s", e); 1822 return -1; 1823 case MUX_S_FAILURE: 1824 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1825 fatal_fr(r, "parse error message"); 1826 sshbuf_free(m); 1827 error_f("forwarding request failed: %s", e); 1828 return -1; 1829 default: 1830 fatal_f("unexpected response from master 0x%08x", type); 1831 } 1832 sshbuf_free(m); 1833 1834 muxclient_request_id++; 1835 return 0; 1836 } 1837 1838 static int 1839 mux_client_forwards(int fd, int cancel_flag) 1840 { 1841 int i, ret = 0; 1842 1843 debug3_f("%s forwardings: %d local, %d remote", 1844 cancel_flag ? "cancel" : "request", 1845 options.num_local_forwards, options.num_remote_forwards); 1846 1847 /* XXX ExitOnForwardingFailure */ 1848 for (i = 0; i < options.num_local_forwards; i++) { 1849 if (mux_client_forward(fd, cancel_flag, 1850 options.local_forwards[i].connect_port == 0 ? 1851 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1852 options.local_forwards + i) != 0) 1853 ret = -1; 1854 } 1855 for (i = 0; i < options.num_remote_forwards; i++) { 1856 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1857 options.remote_forwards + i) != 0) 1858 ret = -1; 1859 } 1860 return ret; 1861 } 1862 1863 static int 1864 mux_client_request_session(int fd) 1865 { 1866 struct sshbuf *m; 1867 char *e; 1868 const char *term = NULL; 1869 u_int i, echar, rid, sid, esid, exitval, type, exitval_seen; 1870 extern char **environ; 1871 int r, rawmode; 1872 1873 debug3_f("entering"); 1874 1875 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1876 error_f("master alive request failed"); 1877 return -1; 1878 } 1879 1880 ssh_signal(SIGPIPE, SIG_IGN); 1881 1882 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 1883 fatal_f("stdfd_devnull failed"); 1884 1885 if ((term = lookup_env_in_list("TERM", options.setenv, 1886 options.num_setenv)) == NULL || *term == '\0') 1887 term = getenv("TERM"); 1888 1889 echar = 0xffffffff; 1890 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1891 echar = (u_int)options.escape_char; 1892 1893 if ((m = sshbuf_new()) == NULL) 1894 fatal_f("sshbuf_new"); 1895 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1896 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1897 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1898 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1899 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1900 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1901 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 || 1902 (r = sshbuf_put_u32(m, echar)) != 0 || 1903 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 || 1904 (r = sshbuf_put_stringb(m, command)) != 0) 1905 fatal_fr(r, "request"); 1906 1907 /* Pass environment */ 1908 if (options.num_send_env > 0 && environ != NULL) { 1909 for (i = 0; environ[i] != NULL; i++) { 1910 if (!env_permitted(environ[i])) 1911 continue; 1912 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1913 fatal_fr(r, "request sendenv"); 1914 } 1915 } 1916 for (i = 0; i < options.num_setenv; i++) { 1917 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1918 fatal_fr(r, "request setenv"); 1919 } 1920 1921 if (mux_client_write_packet(fd, m) != 0) 1922 fatal_f("write packet: %s", strerror(errno)); 1923 1924 /* Send the stdio file descriptors */ 1925 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1926 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1927 mm_send_fd(fd, STDERR_FILENO) == -1) 1928 fatal_f("send fds failed"); 1929 1930 debug3_f("session request sent"); 1931 1932 /* Read their reply */ 1933 sshbuf_reset(m); 1934 if (mux_client_read_packet(fd, m) != 0) { 1935 error_f("read from master failed: %s", strerror(errno)); 1936 sshbuf_free(m); 1937 return -1; 1938 } 1939 1940 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1941 (r = sshbuf_get_u32(m, &rid)) != 0) 1942 fatal_fr(r, "parse"); 1943 if (rid != muxclient_request_id) 1944 fatal_f("out of sequence reply: my id %u theirs %u", 1945 muxclient_request_id, rid); 1946 1947 switch (type) { 1948 case MUX_S_SESSION_OPENED: 1949 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1950 fatal_fr(r, "parse session ID"); 1951 debug_f("master session id: %u", sid); 1952 break; 1953 case MUX_S_PERMISSION_DENIED: 1954 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1955 fatal_fr(r, "parse error message"); 1956 error("Master refused session request: %s", e); 1957 sshbuf_free(m); 1958 return -1; 1959 case MUX_S_FAILURE: 1960 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1961 fatal_fr(r, "parse error message"); 1962 error_f("session request failed: %s", e); 1963 sshbuf_free(m); 1964 return -1; 1965 default: 1966 sshbuf_free(m); 1967 error_f("unexpected response from master 0x%08x", type); 1968 return -1; 1969 } 1970 muxclient_request_id++; 1971 1972 if (pledge("stdio proc tty", NULL) == -1) 1973 fatal_f("pledge(): %s", strerror(errno)); 1974 platform_pledge_mux(); 1975 1976 ssh_signal(SIGHUP, control_client_sighandler); 1977 ssh_signal(SIGINT, control_client_sighandler); 1978 ssh_signal(SIGTERM, control_client_sighandler); 1979 ssh_signal(SIGWINCH, control_client_sigrelay); 1980 1981 rawmode = tty_flag; 1982 if (tty_flag) 1983 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1984 1985 /* 1986 * Stick around until the controlee closes the client_fd. 1987 * Before it does, it is expected to write an exit message. 1988 * This process must read the value and wait for the closure of 1989 * the client_fd; if this one closes early, the multiplex master will 1990 * terminate early too (possibly losing data). 1991 */ 1992 for (exitval = 255, exitval_seen = 0;;) { 1993 sshbuf_reset(m); 1994 if (mux_client_read_packet(fd, m) != 0) 1995 break; 1996 if ((r = sshbuf_get_u32(m, &type)) != 0) 1997 fatal_fr(r, "parse type"); 1998 switch (type) { 1999 case MUX_S_TTY_ALLOC_FAIL: 2000 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2001 fatal_fr(r, "parse session ID"); 2002 if (esid != sid) 2003 fatal_f("tty alloc fail on unknown session: " 2004 "my id %u theirs %u", sid, esid); 2005 leave_raw_mode(options.request_tty == 2006 REQUEST_TTY_FORCE); 2007 rawmode = 0; 2008 continue; 2009 case MUX_S_EXIT_MESSAGE: 2010 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2011 fatal_fr(r, "parse session ID"); 2012 if (esid != sid) 2013 fatal_f("exit on unknown session: " 2014 "my id %u theirs %u", sid, esid); 2015 if (exitval_seen) 2016 fatal_f("exitval sent twice"); 2017 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2018 fatal_fr(r, "parse exitval"); 2019 exitval_seen = 1; 2020 continue; 2021 default: 2022 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2023 fatal_fr(r, "parse error message"); 2024 fatal_f("master returned error: %s", e); 2025 } 2026 } 2027 2028 close(fd); 2029 if (rawmode) 2030 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2031 2032 if (muxclient_terminate) { 2033 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2034 exitval = 255; 2035 } else if (!exitval_seen) { 2036 debug2("Control master terminated unexpectedly"); 2037 exitval = 255; 2038 } else 2039 debug2("Received exit status from master %d", exitval); 2040 2041 if (tty_flag && options.log_level >= SYSLOG_LEVEL_INFO) 2042 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2043 2044 exit(exitval); 2045 } 2046 2047 static int 2048 mux_client_proxy(int fd) 2049 { 2050 struct sshbuf *m; 2051 char *e; 2052 u_int type, rid; 2053 int r; 2054 2055 if ((m = sshbuf_new()) == NULL) 2056 fatal_f("sshbuf_new"); 2057 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2058 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2059 fatal_fr(r, "request"); 2060 if (mux_client_write_packet(fd, m) != 0) 2061 fatal_f("write packet: %s", strerror(errno)); 2062 2063 sshbuf_reset(m); 2064 2065 /* Read their reply */ 2066 if (mux_client_read_packet(fd, m) != 0) { 2067 sshbuf_free(m); 2068 return 0; 2069 } 2070 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2071 (r = sshbuf_get_u32(m, &rid)) != 0) 2072 fatal_fr(r, "parse"); 2073 if (rid != muxclient_request_id) 2074 fatal_f("out of sequence reply: my id %u theirs %u", 2075 muxclient_request_id, rid); 2076 if (type != MUX_S_PROXY) { 2077 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2078 fatal_fr(r, "parse error message"); 2079 fatal_f("master returned error: %s", e); 2080 } 2081 sshbuf_free(m); 2082 2083 debug3_f("done"); 2084 muxclient_request_id++; 2085 return 0; 2086 } 2087 2088 static int 2089 mux_client_request_stdio_fwd(int fd) 2090 { 2091 struct sshbuf *m; 2092 char *e; 2093 u_int type, rid, sid; 2094 int r; 2095 2096 debug3_f("entering"); 2097 2098 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2099 error_f("master alive request failed"); 2100 return -1; 2101 } 2102 2103 ssh_signal(SIGPIPE, SIG_IGN); 2104 2105 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 2106 fatal_f("stdfd_devnull failed"); 2107 2108 if ((m = sshbuf_new()) == NULL) 2109 fatal_f("sshbuf_new"); 2110 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2111 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2112 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2113 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2114 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2115 fatal_fr(r, "request"); 2116 2117 if (mux_client_write_packet(fd, m) != 0) 2118 fatal_f("write packet: %s", strerror(errno)); 2119 2120 /* Send the stdio file descriptors */ 2121 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2122 mm_send_fd(fd, STDOUT_FILENO) == -1) 2123 fatal_f("send fds failed"); 2124 2125 if (pledge("stdio proc tty", NULL) == -1) 2126 fatal_f("pledge(): %s", strerror(errno)); 2127 platform_pledge_mux(); 2128 2129 debug3_f("stdio forward request sent"); 2130 2131 /* Read their reply */ 2132 sshbuf_reset(m); 2133 2134 if (mux_client_read_packet(fd, m) != 0) { 2135 error_f("read from master failed: %s", strerror(errno)); 2136 sshbuf_free(m); 2137 return -1; 2138 } 2139 2140 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2141 (r = sshbuf_get_u32(m, &rid)) != 0) 2142 fatal_fr(r, "parse"); 2143 if (rid != muxclient_request_id) 2144 fatal_f("out of sequence reply: my id %u theirs %u", 2145 muxclient_request_id, rid); 2146 switch (type) { 2147 case MUX_S_SESSION_OPENED: 2148 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2149 fatal_fr(r, "parse session ID"); 2150 debug_f("master session id: %u", sid); 2151 break; 2152 case MUX_S_PERMISSION_DENIED: 2153 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2154 fatal_fr(r, "parse error message"); 2155 sshbuf_free(m); 2156 fatal("Master refused stdio forwarding request: %s", e); 2157 case MUX_S_FAILURE: 2158 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2159 fatal_fr(r, "parse error message"); 2160 sshbuf_free(m); 2161 fatal("Stdio forwarding request failed: %s", e); 2162 default: 2163 sshbuf_free(m); 2164 error_f("unexpected response from master 0x%08x", type); 2165 return -1; 2166 } 2167 muxclient_request_id++; 2168 2169 ssh_signal(SIGHUP, control_client_sighandler); 2170 ssh_signal(SIGINT, control_client_sighandler); 2171 ssh_signal(SIGTERM, control_client_sighandler); 2172 ssh_signal(SIGWINCH, control_client_sigrelay); 2173 2174 /* 2175 * Stick around until the controlee closes the client_fd. 2176 */ 2177 sshbuf_reset(m); 2178 if (mux_client_read_packet(fd, m) != 0) { 2179 if (errno == EPIPE || 2180 (errno == EINTR && muxclient_terminate != 0)) 2181 return 0; 2182 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2183 } 2184 fatal_f("master returned unexpected message %u", type); 2185 } 2186 2187 static void 2188 mux_client_request_stop_listening(int fd) 2189 { 2190 struct sshbuf *m; 2191 char *e; 2192 u_int type, rid; 2193 int r; 2194 2195 debug3_f("entering"); 2196 2197 if ((m = sshbuf_new()) == NULL) 2198 fatal_f("sshbuf_new"); 2199 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2200 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2201 fatal_fr(r, "request"); 2202 2203 if (mux_client_write_packet(fd, m) != 0) 2204 fatal_f("write packet: %s", strerror(errno)); 2205 2206 sshbuf_reset(m); 2207 2208 /* Read their reply */ 2209 if (mux_client_read_packet(fd, m) != 0) 2210 fatal_f("read from master failed: %s", strerror(errno)); 2211 2212 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2213 (r = sshbuf_get_u32(m, &rid)) != 0) 2214 fatal_fr(r, "parse"); 2215 if (rid != muxclient_request_id) 2216 fatal_f("out of sequence reply: my id %u theirs %u", 2217 muxclient_request_id, rid); 2218 2219 switch (type) { 2220 case MUX_S_OK: 2221 break; 2222 case MUX_S_PERMISSION_DENIED: 2223 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2224 fatal_fr(r, "parse error message"); 2225 fatal("Master refused stop listening request: %s", e); 2226 case MUX_S_FAILURE: 2227 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2228 fatal_fr(r, "parse error message"); 2229 fatal_f("stop listening request failed: %s", e); 2230 default: 2231 fatal_f("unexpected response from master 0x%08x", type); 2232 } 2233 sshbuf_free(m); 2234 muxclient_request_id++; 2235 } 2236 2237 /* Multiplex client main loop. */ 2238 int 2239 muxclient(const char *path) 2240 { 2241 struct sockaddr_un addr; 2242 int sock; 2243 u_int pid; 2244 2245 if (muxclient_command == 0) { 2246 if (options.stdio_forward_host != NULL) 2247 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2248 else 2249 muxclient_command = SSHMUX_COMMAND_OPEN; 2250 } 2251 2252 switch (options.control_master) { 2253 case SSHCTL_MASTER_AUTO: 2254 case SSHCTL_MASTER_AUTO_ASK: 2255 debug("auto-mux: Trying existing master"); 2256 /* FALLTHROUGH */ 2257 case SSHCTL_MASTER_NO: 2258 break; 2259 default: 2260 return -1; 2261 } 2262 2263 memset(&addr, '\0', sizeof(addr)); 2264 addr.sun_family = AF_UNIX; 2265 2266 if (strlcpy(addr.sun_path, path, 2267 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2268 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2269 (unsigned int)sizeof(addr.sun_path)); 2270 2271 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2272 fatal_f("socket(): %s", strerror(errno)); 2273 2274 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2275 switch (muxclient_command) { 2276 case SSHMUX_COMMAND_OPEN: 2277 case SSHMUX_COMMAND_STDIO_FWD: 2278 break; 2279 default: 2280 fatal("Control socket connect(%.100s): %s", path, 2281 strerror(errno)); 2282 } 2283 if (errno == ECONNREFUSED && 2284 options.control_master != SSHCTL_MASTER_NO) { 2285 debug("Stale control socket %.100s, unlinking", path); 2286 unlink(path); 2287 } else if (errno == ENOENT) { 2288 debug("Control socket \"%.100s\" does not exist", path); 2289 } else { 2290 error("Control socket connect(%.100s): %s", path, 2291 strerror(errno)); 2292 } 2293 close(sock); 2294 return -1; 2295 } 2296 set_nonblock(sock); 2297 2298 if (mux_client_hello_exchange(sock) != 0) { 2299 error_f("master hello exchange failed"); 2300 close(sock); 2301 return -1; 2302 } 2303 2304 switch (muxclient_command) { 2305 case SSHMUX_COMMAND_ALIVE_CHECK: 2306 if ((pid = mux_client_request_alive(sock)) == 0) 2307 fatal_f("master alive check failed"); 2308 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2309 exit(0); 2310 case SSHMUX_COMMAND_TERMINATE: 2311 mux_client_request_terminate(sock); 2312 if (options.log_level != SYSLOG_LEVEL_QUIET) 2313 fprintf(stderr, "Exit request sent.\r\n"); 2314 exit(0); 2315 case SSHMUX_COMMAND_FORWARD: 2316 if (mux_client_forwards(sock, 0) != 0) 2317 fatal_f("master forward request failed"); 2318 exit(0); 2319 case SSHMUX_COMMAND_OPEN: 2320 if (mux_client_forwards(sock, 0) != 0) { 2321 error_f("master forward request failed"); 2322 return -1; 2323 } 2324 mux_client_request_session(sock); 2325 return -1; 2326 case SSHMUX_COMMAND_STDIO_FWD: 2327 mux_client_request_stdio_fwd(sock); 2328 exit(0); 2329 case SSHMUX_COMMAND_STOP: 2330 mux_client_request_stop_listening(sock); 2331 if (options.log_level != SYSLOG_LEVEL_QUIET) 2332 fprintf(stderr, "Stop listening request sent.\r\n"); 2333 exit(0); 2334 case SSHMUX_COMMAND_CANCEL_FWD: 2335 if (mux_client_forwards(sock, 1) != 0) 2336 error_f("master cancel forward request failed"); 2337 exit(0); 2338 case SSHMUX_COMMAND_PROXY: 2339 mux_client_proxy(sock); 2340 return (sock); 2341 default: 2342 fatal("unrecognised muxclient_command %d", muxclient_command); 2343 } 2344 } 2345