1 /* $OpenBSD: mux.c,v 1.99 2023/08/04 06:32:40 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 #include <sys/types.h> 21 #include <sys/queue.h> 22 #include <sys/stat.h> 23 #include <sys/socket.h> 24 #include <sys/un.h> 25 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <poll.h> 29 #include <limits.h> 30 #include <signal.h> 31 #include <stdarg.h> 32 #include <stddef.h> 33 #include <stdlib.h> 34 #include <stdio.h> 35 #include <string.h> 36 #include <unistd.h> 37 #include <util.h> 38 #include <paths.h> 39 40 #include "atomicio.h" 41 #include "xmalloc.h" 42 #include "log.h" 43 #include "ssh.h" 44 #include "ssh2.h" 45 #include "pathnames.h" 46 #include "misc.h" 47 #include "match.h" 48 #include "sshbuf.h" 49 #include "channels.h" 50 #include "msg.h" 51 #include "packet.h" 52 #include "monitor_fdpass.h" 53 #include "sshpty.h" 54 #include "sshkey.h" 55 #include "readconf.h" 56 #include "clientloop.h" 57 #include "ssherr.h" 58 #include "misc.h" 59 60 /* from ssh.c */ 61 extern int tty_flag; 62 extern Options options; 63 extern char *host; 64 extern struct sshbuf *command; 65 extern volatile sig_atomic_t quit_pending; 66 67 /* Context for session open confirmation callback */ 68 struct mux_session_confirm_ctx { 69 u_int want_tty; 70 u_int want_subsys; 71 u_int want_x_fwd; 72 u_int want_agent_fwd; 73 struct sshbuf *cmd; 74 char *term; 75 struct termios tio; 76 char **env; 77 u_int rid; 78 }; 79 80 /* Context for stdio fwd open confirmation callback */ 81 struct mux_stdio_confirm_ctx { 82 u_int rid; 83 }; 84 85 /* Context for global channel callback */ 86 struct mux_channel_confirm_ctx { 87 u_int cid; /* channel id */ 88 u_int rid; /* request id */ 89 int fid; /* forward id */ 90 }; 91 92 /* fd to control socket */ 93 int muxserver_sock = -1; 94 95 /* client request id */ 96 u_int muxclient_request_id = 0; 97 98 /* Multiplexing control command */ 99 u_int muxclient_command = 0; 100 101 /* Set when signalled. */ 102 static volatile sig_atomic_t muxclient_terminate = 0; 103 104 /* PID of multiplex server */ 105 static u_int muxserver_pid = 0; 106 107 static Channel *mux_listener_channel = NULL; 108 109 struct mux_master_state { 110 int hello_rcvd; 111 }; 112 113 /* mux protocol messages */ 114 #define MUX_MSG_HELLO 0x00000001 115 #define MUX_C_NEW_SESSION 0x10000002 116 #define MUX_C_ALIVE_CHECK 0x10000004 117 #define MUX_C_TERMINATE 0x10000005 118 #define MUX_C_OPEN_FWD 0x10000006 119 #define MUX_C_CLOSE_FWD 0x10000007 120 #define MUX_C_NEW_STDIO_FWD 0x10000008 121 #define MUX_C_STOP_LISTENING 0x10000009 122 #define MUX_C_PROXY 0x1000000f 123 #define MUX_S_OK 0x80000001 124 #define MUX_S_PERMISSION_DENIED 0x80000002 125 #define MUX_S_FAILURE 0x80000003 126 #define MUX_S_EXIT_MESSAGE 0x80000004 127 #define MUX_S_ALIVE 0x80000005 128 #define MUX_S_SESSION_OPENED 0x80000006 129 #define MUX_S_REMOTE_PORT 0x80000007 130 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 131 #define MUX_S_PROXY 0x8000000f 132 133 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 134 #define MUX_FWD_LOCAL 1 135 #define MUX_FWD_REMOTE 2 136 #define MUX_FWD_DYNAMIC 3 137 138 static void mux_session_confirm(struct ssh *, int, int, void *); 139 static void mux_stdio_confirm(struct ssh *, int, int, void *); 140 141 static int mux_master_process_hello(struct ssh *, u_int, 142 Channel *, struct sshbuf *, struct sshbuf *); 143 static int mux_master_process_new_session(struct ssh *, u_int, 144 Channel *, struct sshbuf *, struct sshbuf *); 145 static int mux_master_process_alive_check(struct ssh *, u_int, 146 Channel *, struct sshbuf *, struct sshbuf *); 147 static int mux_master_process_terminate(struct ssh *, u_int, 148 Channel *, struct sshbuf *, struct sshbuf *); 149 static int mux_master_process_open_fwd(struct ssh *, u_int, 150 Channel *, struct sshbuf *, struct sshbuf *); 151 static int mux_master_process_close_fwd(struct ssh *, u_int, 152 Channel *, struct sshbuf *, struct sshbuf *); 153 static int mux_master_process_stdio_fwd(struct ssh *, u_int, 154 Channel *, struct sshbuf *, struct sshbuf *); 155 static int mux_master_process_stop_listening(struct ssh *, u_int, 156 Channel *, struct sshbuf *, struct sshbuf *); 157 static int mux_master_process_proxy(struct ssh *, u_int, 158 Channel *, struct sshbuf *, struct sshbuf *); 159 160 static const struct { 161 u_int type; 162 int (*handler)(struct ssh *, u_int, Channel *, 163 struct sshbuf *, struct sshbuf *); 164 } mux_master_handlers[] = { 165 { MUX_MSG_HELLO, mux_master_process_hello }, 166 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 167 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 168 { MUX_C_TERMINATE, mux_master_process_terminate }, 169 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 170 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 171 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 172 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 173 { MUX_C_PROXY, mux_master_process_proxy }, 174 { 0, NULL } 175 }; 176 177 /* Cleanup callback fired on closure of mux client _session_ channel */ 178 static void 179 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 180 { 181 Channel *cc, *c = channel_by_id(ssh, cid); 182 183 debug3_f("entering for channel %d", cid); 184 if (c == NULL) 185 fatal_f("channel_by_id(%i) == NULL", cid); 186 if (c->ctl_chan != -1) { 187 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 188 fatal_f("channel %d missing control channel %d", 189 c->self, c->ctl_chan); 190 c->ctl_chan = -1; 191 cc->remote_id = 0; 192 cc->have_remote_id = 0; 193 chan_rcvd_oclose(ssh, cc); 194 } 195 channel_cancel_cleanup(ssh, c->self); 196 } 197 198 /* Cleanup callback fired on closure of mux client _control_ channel */ 199 static void 200 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 201 { 202 Channel *sc, *c = channel_by_id(ssh, cid); 203 204 debug3_f("entering for channel %d", cid); 205 if (c == NULL) 206 fatal_f("channel_by_id(%i) == NULL", cid); 207 if (c->have_remote_id) { 208 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 209 fatal_f("channel %d missing session channel %u", 210 c->self, c->remote_id); 211 c->remote_id = 0; 212 c->have_remote_id = 0; 213 sc->ctl_chan = -1; 214 if (sc->type != SSH_CHANNEL_OPEN && 215 sc->type != SSH_CHANNEL_OPENING) { 216 debug2_f("channel %d: not open", sc->self); 217 chan_mark_dead(ssh, sc); 218 } else { 219 if (sc->istate == CHAN_INPUT_OPEN) 220 chan_read_failed(ssh, sc); 221 if (sc->ostate == CHAN_OUTPUT_OPEN) 222 chan_write_failed(ssh, sc); 223 } 224 } 225 channel_cancel_cleanup(ssh, c->self); 226 } 227 228 /* Check mux client environment variables before passing them to mux master. */ 229 static int 230 env_permitted(const char *env) 231 { 232 u_int i; 233 int ret; 234 char name[1024], *cp; 235 236 if ((cp = strchr(env, '=')) == NULL || cp == env) 237 return 0; 238 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 239 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 240 error_f("name '%.100s...' too long", env); 241 return 0; 242 } 243 244 for (i = 0; i < options.num_send_env; i++) 245 if (match_pattern(name, options.send_env[i])) 246 return 1; 247 248 return 0; 249 } 250 251 /* Mux master protocol message handlers */ 252 253 static int 254 mux_master_process_hello(struct ssh *ssh, u_int rid, 255 Channel *c, struct sshbuf *m, struct sshbuf *reply) 256 { 257 u_int ver; 258 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 259 int r; 260 261 if (state == NULL) 262 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 263 if (state->hello_rcvd) { 264 error_f("HELLO received twice"); 265 return -1; 266 } 267 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 268 error_fr(r, "parse"); 269 return -1; 270 } 271 if (ver != SSHMUX_VER) { 272 error_f("unsupported multiplexing protocol version %u " 273 "(expected %u)", ver, SSHMUX_VER); 274 return -1; 275 } 276 debug2_f("channel %d client version %u", c->self, ver); 277 278 /* No extensions are presently defined */ 279 while (sshbuf_len(m) > 0) { 280 char *name = NULL; 281 size_t value_len = 0; 282 283 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 284 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 285 error_fr(r, "parse extension"); 286 return -1; 287 } 288 debug2_f("Unrecognised extension \"%s\" length %zu", 289 name, value_len); 290 free(name); 291 } 292 state->hello_rcvd = 1; 293 return 0; 294 } 295 296 /* Enqueue a "ok" response to the reply buffer */ 297 static void 298 reply_ok(struct sshbuf *reply, u_int rid) 299 { 300 int r; 301 302 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 303 (r = sshbuf_put_u32(reply, rid)) != 0) 304 fatal_fr(r, "reply"); 305 } 306 307 /* Enqueue an error response to the reply buffer */ 308 static void 309 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 310 { 311 int r; 312 313 if ((r = sshbuf_put_u32(reply, type)) != 0 || 314 (r = sshbuf_put_u32(reply, rid)) != 0 || 315 (r = sshbuf_put_cstring(reply, msg)) != 0) 316 fatal_fr(r, "reply"); 317 } 318 319 static int 320 mux_master_process_new_session(struct ssh *ssh, u_int rid, 321 Channel *c, struct sshbuf *m, struct sshbuf *reply) 322 { 323 Channel *nc; 324 struct mux_session_confirm_ctx *cctx; 325 char *cmd, *cp; 326 u_int i, j, env_len, escape_char, window, packetmax; 327 int r, new_fd[3]; 328 329 /* Reply for SSHMUX_COMMAND_OPEN */ 330 cctx = xcalloc(1, sizeof(*cctx)); 331 cctx->term = NULL; 332 cctx->rid = rid; 333 cmd = NULL; 334 cctx->env = NULL; 335 env_len = 0; 336 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 337 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 338 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 339 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 340 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 341 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 342 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 343 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 344 malf: 345 free(cmd); 346 for (j = 0; j < env_len; j++) 347 free(cctx->env[j]); 348 free(cctx->env); 349 free(cctx->term); 350 free(cctx); 351 error_f("malformed message"); 352 return -1; 353 } 354 355 #define MUX_MAX_ENV_VARS 4096 356 while (sshbuf_len(m) > 0) { 357 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 358 goto malf; 359 if (!env_permitted(cp)) { 360 free(cp); 361 continue; 362 } 363 cctx->env = xreallocarray(cctx->env, env_len + 2, 364 sizeof(*cctx->env)); 365 cctx->env[env_len++] = cp; 366 cctx->env[env_len] = NULL; 367 if (env_len > MUX_MAX_ENV_VARS) { 368 error_f(">%d environment variables received, " 369 "ignoring additional", MUX_MAX_ENV_VARS); 370 break; 371 } 372 } 373 374 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 375 "term \"%s\", cmd \"%s\", env %u", c->self, 376 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 377 cctx->want_subsys, cctx->term, cmd, env_len); 378 379 if ((cctx->cmd = sshbuf_new()) == NULL) 380 fatal_f("sshbuf_new"); 381 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 382 fatal_fr(r, "sshbuf_put"); 383 free(cmd); 384 cmd = NULL; 385 386 /* Gather fds from client */ 387 for(i = 0; i < 3; i++) { 388 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 389 error_f("failed to receive fd %d from client", i); 390 for (j = 0; j < i; j++) 391 close(new_fd[j]); 392 for (j = 0; j < env_len; j++) 393 free(cctx->env[j]); 394 free(cctx->env); 395 free(cctx->term); 396 sshbuf_free(cctx->cmd); 397 free(cctx); 398 reply_error(reply, MUX_S_FAILURE, rid, 399 "did not receive file descriptors"); 400 return -1; 401 } 402 } 403 404 debug3_f("got fds stdin %d, stdout %d, stderr %d", 405 new_fd[0], new_fd[1], new_fd[2]); 406 407 /* XXX support multiple child sessions in future */ 408 if (c->have_remote_id) { 409 debug2_f("session already open"); 410 reply_error(reply, MUX_S_FAILURE, rid, 411 "Multiple sessions not supported"); 412 cleanup: 413 close(new_fd[0]); 414 close(new_fd[1]); 415 close(new_fd[2]); 416 free(cctx->term); 417 if (env_len != 0) { 418 for (i = 0; i < env_len; i++) 419 free(cctx->env[i]); 420 free(cctx->env); 421 } 422 sshbuf_free(cctx->cmd); 423 free(cctx); 424 return 0; 425 } 426 427 if (options.control_master == SSHCTL_MASTER_ASK || 428 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 429 if (!ask_permission("Allow shared connection to %s? ", host)) { 430 debug2_f("session refused by user"); 431 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 432 "Permission denied"); 433 goto cleanup; 434 } 435 } 436 437 /* Try to pick up ttymodes from client before it goes raw */ 438 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 439 error_f("tcgetattr: %s", strerror(errno)); 440 441 window = CHAN_SES_WINDOW_DEFAULT; 442 packetmax = CHAN_SES_PACKET_DEFAULT; 443 if (cctx->want_tty) { 444 window >>= 1; 445 packetmax >>= 1; 446 } 447 448 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 449 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 450 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO); 451 452 nc->ctl_chan = c->self; /* link session -> control channel */ 453 c->remote_id = nc->self; /* link control -> session channel */ 454 c->have_remote_id = 1; 455 456 if (cctx->want_tty && escape_char != 0xffffffff) { 457 channel_register_filter(ssh, nc->self, 458 client_simple_escape_filter, NULL, 459 client_filter_cleanup, 460 client_new_escape_filter_ctx((int)escape_char)); 461 } 462 463 debug2_f("channel_new: %d linked to control channel %d", 464 nc->self, nc->ctl_chan); 465 466 channel_send_open(ssh, nc->self); 467 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 468 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 469 channel_register_cleanup(ssh, nc->self, 470 mux_master_session_cleanup_cb, 1); 471 472 /* reply is deferred, sent by mux_session_confirm */ 473 return 0; 474 } 475 476 static int 477 mux_master_process_alive_check(struct ssh *ssh, u_int rid, 478 Channel *c, struct sshbuf *m, struct sshbuf *reply) 479 { 480 int r; 481 482 debug2_f("channel %d: alive check", c->self); 483 484 /* prepare reply */ 485 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 486 (r = sshbuf_put_u32(reply, rid)) != 0 || 487 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 488 fatal_fr(r, "reply"); 489 490 return 0; 491 } 492 493 static int 494 mux_master_process_terminate(struct ssh *ssh, u_int rid, 495 Channel *c, struct sshbuf *m, struct sshbuf *reply) 496 { 497 debug2_f("channel %d: terminate request", c->self); 498 499 if (options.control_master == SSHCTL_MASTER_ASK || 500 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 501 if (!ask_permission("Terminate shared connection to %s? ", 502 host)) { 503 debug2_f("termination refused by user"); 504 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 505 "Permission denied"); 506 return 0; 507 } 508 } 509 510 quit_pending = 1; 511 reply_ok(reply, rid); 512 /* XXX exit happens too soon - message never makes it to client */ 513 return 0; 514 } 515 516 static char * 517 format_forward(u_int ftype, struct Forward *fwd) 518 { 519 char *ret; 520 521 switch (ftype) { 522 case MUX_FWD_LOCAL: 523 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 524 (fwd->listen_path != NULL) ? fwd->listen_path : 525 (fwd->listen_host == NULL) ? 526 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 527 fwd->listen_host, fwd->listen_port, 528 (fwd->connect_path != NULL) ? fwd->connect_path : 529 fwd->connect_host, fwd->connect_port); 530 break; 531 case MUX_FWD_DYNAMIC: 532 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 533 (fwd->listen_host == NULL) ? 534 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 535 fwd->listen_host, fwd->listen_port); 536 break; 537 case MUX_FWD_REMOTE: 538 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 539 (fwd->listen_path != NULL) ? fwd->listen_path : 540 (fwd->listen_host == NULL) ? 541 "LOCALHOST" : fwd->listen_host, 542 fwd->listen_port, 543 (fwd->connect_path != NULL) ? fwd->connect_path : 544 fwd->connect_host, fwd->connect_port); 545 break; 546 default: 547 fatal_f("unknown forward type %u", ftype); 548 } 549 return ret; 550 } 551 552 static int 553 compare_host(const char *a, const char *b) 554 { 555 if (a == NULL && b == NULL) 556 return 1; 557 if (a == NULL || b == NULL) 558 return 0; 559 return strcmp(a, b) == 0; 560 } 561 562 static int 563 compare_forward(struct Forward *a, struct Forward *b) 564 { 565 if (!compare_host(a->listen_host, b->listen_host)) 566 return 0; 567 if (!compare_host(a->listen_path, b->listen_path)) 568 return 0; 569 if (a->listen_port != b->listen_port) 570 return 0; 571 if (!compare_host(a->connect_host, b->connect_host)) 572 return 0; 573 if (!compare_host(a->connect_path, b->connect_path)) 574 return 0; 575 if (a->connect_port != b->connect_port) 576 return 0; 577 578 return 1; 579 } 580 581 static void 582 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 583 { 584 struct mux_channel_confirm_ctx *fctx = ctxt; 585 char *failmsg = NULL; 586 struct Forward *rfwd; 587 Channel *c; 588 struct sshbuf *out; 589 u_int port; 590 int r; 591 592 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 593 /* no channel for reply */ 594 error_f("unknown channel"); 595 return; 596 } 597 if ((out = sshbuf_new()) == NULL) 598 fatal_f("sshbuf_new"); 599 if (fctx->fid >= options.num_remote_forwards || 600 (options.remote_forwards[fctx->fid].connect_path == NULL && 601 options.remote_forwards[fctx->fid].connect_host == NULL)) { 602 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 603 goto fail; 604 } 605 rfwd = &options.remote_forwards[fctx->fid]; 606 debug_f("%s for: listen %d, connect %s:%d", 607 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 608 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 609 rfwd->connect_host, rfwd->connect_port); 610 if (type == SSH2_MSG_REQUEST_SUCCESS) { 611 if (rfwd->listen_port == 0) { 612 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 613 fatal_fr(r, "parse port"); 614 if (port > 65535) { 615 fatal("Invalid allocated port %u for " 616 "mux remote forward to %s:%d", port, 617 rfwd->connect_host, rfwd->connect_port); 618 } 619 rfwd->allocated_port = (int)port; 620 debug("Allocated port %u for mux remote forward" 621 " to %s:%d", rfwd->allocated_port, 622 rfwd->connect_host, rfwd->connect_port); 623 if ((r = sshbuf_put_u32(out, 624 MUX_S_REMOTE_PORT)) != 0 || 625 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 626 (r = sshbuf_put_u32(out, 627 rfwd->allocated_port)) != 0) 628 fatal_fr(r, "reply"); 629 channel_update_permission(ssh, rfwd->handle, 630 rfwd->allocated_port); 631 } else { 632 reply_ok(out, fctx->rid); 633 } 634 goto out; 635 } else { 636 if (rfwd->listen_port == 0) 637 channel_update_permission(ssh, rfwd->handle, -1); 638 if (rfwd->listen_path != NULL) 639 xasprintf(&failmsg, "remote port forwarding failed for " 640 "listen path %s", rfwd->listen_path); 641 else 642 xasprintf(&failmsg, "remote port forwarding failed for " 643 "listen port %d", rfwd->listen_port); 644 645 debug2_f("clearing registered forwarding for listen %d, " 646 "connect %s:%d", rfwd->listen_port, 647 rfwd->connect_path ? rfwd->connect_path : 648 rfwd->connect_host, rfwd->connect_port); 649 650 free(rfwd->listen_host); 651 free(rfwd->listen_path); 652 free(rfwd->connect_host); 653 free(rfwd->connect_path); 654 memset(rfwd, 0, sizeof(*rfwd)); 655 } 656 fail: 657 error_f("%s", failmsg); 658 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 659 free(failmsg); 660 out: 661 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 662 fatal_fr(r, "enqueue"); 663 sshbuf_free(out); 664 if (c->mux_pause <= 0) 665 fatal_f("mux_pause %d", c->mux_pause); 666 c->mux_pause = 0; /* start processing messages again */ 667 } 668 669 static int 670 mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 671 Channel *c, struct sshbuf *m, struct sshbuf *reply) 672 { 673 struct Forward fwd; 674 char *fwd_desc = NULL; 675 char *listen_addr, *connect_addr; 676 u_int ftype; 677 u_int lport, cport; 678 int r, i, ret = 0, freefwd = 1; 679 680 memset(&fwd, 0, sizeof(fwd)); 681 682 /* XXX - lport/cport check redundant */ 683 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 684 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 685 (r = sshbuf_get_u32(m, &lport)) != 0 || 686 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 687 (r = sshbuf_get_u32(m, &cport)) != 0 || 688 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 689 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 690 error_f("malformed message"); 691 ret = -1; 692 goto out; 693 } 694 if (*listen_addr == '\0') { 695 free(listen_addr); 696 listen_addr = NULL; 697 } 698 if (*connect_addr == '\0') { 699 free(connect_addr); 700 connect_addr = NULL; 701 } 702 703 memset(&fwd, 0, sizeof(fwd)); 704 fwd.listen_port = lport; 705 if (fwd.listen_port == PORT_STREAMLOCAL) 706 fwd.listen_path = listen_addr; 707 else 708 fwd.listen_host = listen_addr; 709 fwd.connect_port = cport; 710 if (fwd.connect_port == PORT_STREAMLOCAL) 711 fwd.connect_path = connect_addr; 712 else 713 fwd.connect_host = connect_addr; 714 715 debug2_f("channel %d: request %s", c->self, 716 (fwd_desc = format_forward(ftype, &fwd))); 717 718 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 719 ftype != MUX_FWD_DYNAMIC) { 720 logit_f("invalid forwarding type %u", ftype); 721 invalid: 722 free(listen_addr); 723 free(connect_addr); 724 reply_error(reply, MUX_S_FAILURE, rid, 725 "Invalid forwarding request"); 726 return 0; 727 } 728 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 729 logit_f("streamlocal and dynamic forwards " 730 "are mutually exclusive"); 731 goto invalid; 732 } 733 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 734 logit_f("invalid listen port %u", fwd.listen_port); 735 goto invalid; 736 } 737 if ((fwd.connect_port != PORT_STREAMLOCAL && 738 fwd.connect_port >= 65536) || 739 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 740 fwd.connect_port == 0)) { 741 logit_f("invalid connect port %u", 742 fwd.connect_port); 743 goto invalid; 744 } 745 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 746 fwd.connect_path == NULL) { 747 logit_f("missing connect host"); 748 goto invalid; 749 } 750 751 /* Skip forwards that have already been requested */ 752 switch (ftype) { 753 case MUX_FWD_LOCAL: 754 case MUX_FWD_DYNAMIC: 755 for (i = 0; i < options.num_local_forwards; i++) { 756 if (compare_forward(&fwd, 757 options.local_forwards + i)) { 758 exists: 759 debug2_f("found existing forwarding"); 760 reply_ok(reply, rid); 761 goto out; 762 } 763 } 764 break; 765 case MUX_FWD_REMOTE: 766 for (i = 0; i < options.num_remote_forwards; i++) { 767 if (!compare_forward(&fwd, options.remote_forwards + i)) 768 continue; 769 if (fwd.listen_port != 0) 770 goto exists; 771 debug2_f("found allocated port"); 772 if ((r = sshbuf_put_u32(reply, 773 MUX_S_REMOTE_PORT)) != 0 || 774 (r = sshbuf_put_u32(reply, rid)) != 0 || 775 (r = sshbuf_put_u32(reply, 776 options.remote_forwards[i].allocated_port)) != 0) 777 fatal_fr(r, "reply FWD_REMOTE"); 778 goto out; 779 } 780 break; 781 } 782 783 if (options.control_master == SSHCTL_MASTER_ASK || 784 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 785 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 786 debug2_f("forwarding refused by user"); 787 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 788 "Permission denied"); 789 goto out; 790 } 791 } 792 793 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 794 if (!channel_setup_local_fwd_listener(ssh, &fwd, 795 &options.fwd_opts)) { 796 fail: 797 logit_f("requested %s failed", fwd_desc); 798 reply_error(reply, MUX_S_FAILURE, rid, 799 "Port forwarding failed"); 800 goto out; 801 } 802 add_local_forward(&options, &fwd); 803 freefwd = 0; 804 } else { 805 struct mux_channel_confirm_ctx *fctx; 806 807 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 808 if (fwd.handle < 0) 809 goto fail; 810 add_remote_forward(&options, &fwd); 811 fctx = xcalloc(1, sizeof(*fctx)); 812 fctx->cid = c->self; 813 fctx->rid = rid; 814 fctx->fid = options.num_remote_forwards - 1; 815 client_register_global_confirm(mux_confirm_remote_forward, 816 fctx); 817 freefwd = 0; 818 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 819 /* delayed reply in mux_confirm_remote_forward */ 820 goto out; 821 } 822 reply_ok(reply, rid); 823 out: 824 free(fwd_desc); 825 if (freefwd) { 826 free(fwd.listen_host); 827 free(fwd.listen_path); 828 free(fwd.connect_host); 829 free(fwd.connect_path); 830 } 831 return ret; 832 } 833 834 static int 835 mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 836 Channel *c, struct sshbuf *m, struct sshbuf *reply) 837 { 838 struct Forward fwd, *found_fwd; 839 char *fwd_desc = NULL; 840 const char *error_reason = NULL; 841 char *listen_addr = NULL, *connect_addr = NULL; 842 u_int ftype; 843 int r, i, ret = 0; 844 u_int lport, cport; 845 846 memset(&fwd, 0, sizeof(fwd)); 847 848 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 849 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 850 (r = sshbuf_get_u32(m, &lport)) != 0 || 851 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 852 (r = sshbuf_get_u32(m, &cport)) != 0 || 853 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 854 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 855 error_f("malformed message"); 856 ret = -1; 857 goto out; 858 } 859 860 if (*listen_addr == '\0') { 861 free(listen_addr); 862 listen_addr = NULL; 863 } 864 if (*connect_addr == '\0') { 865 free(connect_addr); 866 connect_addr = NULL; 867 } 868 869 memset(&fwd, 0, sizeof(fwd)); 870 fwd.listen_port = lport; 871 if (fwd.listen_port == PORT_STREAMLOCAL) 872 fwd.listen_path = listen_addr; 873 else 874 fwd.listen_host = listen_addr; 875 fwd.connect_port = cport; 876 if (fwd.connect_port == PORT_STREAMLOCAL) 877 fwd.connect_path = connect_addr; 878 else 879 fwd.connect_host = connect_addr; 880 881 debug2_f("channel %d: request cancel %s", c->self, 882 (fwd_desc = format_forward(ftype, &fwd))); 883 884 /* make sure this has been requested */ 885 found_fwd = NULL; 886 switch (ftype) { 887 case MUX_FWD_LOCAL: 888 case MUX_FWD_DYNAMIC: 889 for (i = 0; i < options.num_local_forwards; i++) { 890 if (compare_forward(&fwd, 891 options.local_forwards + i)) { 892 found_fwd = options.local_forwards + i; 893 break; 894 } 895 } 896 break; 897 case MUX_FWD_REMOTE: 898 for (i = 0; i < options.num_remote_forwards; i++) { 899 if (compare_forward(&fwd, 900 options.remote_forwards + i)) { 901 found_fwd = options.remote_forwards + i; 902 break; 903 } 904 } 905 break; 906 } 907 908 if (found_fwd == NULL) 909 error_reason = "port not forwarded"; 910 else if (ftype == MUX_FWD_REMOTE) { 911 /* 912 * This shouldn't fail unless we confused the host/port 913 * between options.remote_forwards and permitted_opens. 914 * However, for dynamic allocated listen ports we need 915 * to use the actual listen port. 916 */ 917 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 918 error_reason = "port not in permitted opens"; 919 } else { /* local and dynamic forwards */ 920 /* Ditto */ 921 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 922 &options.fwd_opts) == -1) 923 error_reason = "port not found"; 924 } 925 926 if (error_reason != NULL) 927 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 928 else { 929 reply_ok(reply, rid); 930 free(found_fwd->listen_host); 931 free(found_fwd->listen_path); 932 free(found_fwd->connect_host); 933 free(found_fwd->connect_path); 934 found_fwd->listen_host = found_fwd->connect_host = NULL; 935 found_fwd->listen_path = found_fwd->connect_path = NULL; 936 found_fwd->listen_port = found_fwd->connect_port = 0; 937 } 938 out: 939 free(fwd_desc); 940 free(listen_addr); 941 free(connect_addr); 942 943 return ret; 944 } 945 946 static int 947 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 948 Channel *c, struct sshbuf *m, struct sshbuf *reply) 949 { 950 Channel *nc; 951 char *chost = NULL; 952 u_int _cport, i, j; 953 int ok = 0, cport, r, new_fd[2]; 954 struct mux_stdio_confirm_ctx *cctx; 955 956 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 957 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 958 (r = sshbuf_get_u32(m, &_cport)) != 0) { 959 free(chost); 960 error_f("malformed message"); 961 return -1; 962 } 963 if (_cport == (u_int)PORT_STREAMLOCAL) 964 cport = PORT_STREAMLOCAL; 965 else if (_cport <= INT_MAX) 966 cport = (int)_cport; 967 else { 968 free(chost); 969 error_f("invalid port 0x%x", _cport); 970 return -1; 971 } 972 973 debug2_f("channel %d: stdio fwd to %s:%d", c->self, chost, cport); 974 975 /* Gather fds from client */ 976 for(i = 0; i < 2; i++) { 977 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 978 error_f("failed to receive fd %d from client", i); 979 for (j = 0; j < i; j++) 980 close(new_fd[j]); 981 free(chost); 982 983 /* prepare reply */ 984 reply_error(reply, MUX_S_FAILURE, rid, 985 "did not receive file descriptors"); 986 return -1; 987 } 988 } 989 990 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 991 992 /* XXX support multiple child sessions in future */ 993 if (c->have_remote_id) { 994 debug2_f("session already open"); 995 reply_error(reply, MUX_S_FAILURE, rid, 996 "Multiple sessions not supported"); 997 cleanup: 998 close(new_fd[0]); 999 close(new_fd[1]); 1000 free(chost); 1001 return 0; 1002 } 1003 1004 if (options.control_master == SSHCTL_MASTER_ASK || 1005 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1006 if (cport == PORT_STREAMLOCAL) { 1007 ok = ask_permission("Allow forward to path %s", chost); 1008 } else { 1009 ok = ask_permission("Allow forward to [%s]:%d? ", 1010 chost, cport); 1011 } 1012 if (!ok) { 1013 debug2_f("stdio fwd refused by user"); 1014 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1015 "Permission denied"); 1016 goto cleanup; 1017 } 1018 } 1019 1020 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1], 1021 CHANNEL_NONBLOCK_STDIO); 1022 free(chost); 1023 1024 nc->ctl_chan = c->self; /* link session -> control channel */ 1025 c->remote_id = nc->self; /* link control -> session channel */ 1026 c->have_remote_id = 1; 1027 1028 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan); 1029 1030 channel_register_cleanup(ssh, nc->self, 1031 mux_master_session_cleanup_cb, 1); 1032 1033 cctx = xcalloc(1, sizeof(*cctx)); 1034 cctx->rid = rid; 1035 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1036 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1037 1038 /* reply is deferred, sent by mux_session_confirm */ 1039 return 0; 1040 } 1041 1042 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1043 static void 1044 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1045 { 1046 struct mux_stdio_confirm_ctx *cctx = arg; 1047 Channel *c, *cc; 1048 struct sshbuf *reply; 1049 int r; 1050 1051 if (cctx == NULL) 1052 fatal_f("cctx == NULL"); 1053 if ((c = channel_by_id(ssh, id)) == NULL) 1054 fatal_f("no channel for id %d", id); 1055 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1056 fatal_f("channel %d lacks control channel %d", 1057 id, c->ctl_chan); 1058 if ((reply = sshbuf_new()) == NULL) 1059 fatal_f("sshbuf_new"); 1060 1061 if (!success) { 1062 debug3_f("sending failure reply"); 1063 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1064 "Session open refused by peer"); 1065 /* prepare reply */ 1066 goto done; 1067 } 1068 1069 debug3_f("sending success reply"); 1070 /* prepare reply */ 1071 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1072 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1073 (r = sshbuf_put_u32(reply, c->self)) != 0) 1074 fatal_fr(r, "reply"); 1075 1076 done: 1077 /* Send reply */ 1078 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1079 fatal_fr(r, "enqueue"); 1080 sshbuf_free(reply); 1081 1082 if (cc->mux_pause <= 0) 1083 fatal_f("mux_pause %d", cc->mux_pause); 1084 cc->mux_pause = 0; /* start processing messages again */ 1085 c->open_confirm_ctx = NULL; 1086 free(cctx); 1087 } 1088 1089 static int 1090 mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1091 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1092 { 1093 debug_f("channel %d: stop listening", c->self); 1094 1095 if (options.control_master == SSHCTL_MASTER_ASK || 1096 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1097 if (!ask_permission("Disable further multiplexing on shared " 1098 "connection to %s? ", host)) { 1099 debug2_f("stop listen refused by user"); 1100 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1101 "Permission denied"); 1102 return 0; 1103 } 1104 } 1105 1106 if (mux_listener_channel != NULL) { 1107 channel_free(ssh, mux_listener_channel); 1108 client_stop_mux(); 1109 free(options.control_path); 1110 options.control_path = NULL; 1111 mux_listener_channel = NULL; 1112 muxserver_sock = -1; 1113 } 1114 1115 reply_ok(reply, rid); 1116 return 0; 1117 } 1118 1119 static int 1120 mux_master_process_proxy(struct ssh *ssh, u_int rid, 1121 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1122 { 1123 int r; 1124 1125 debug_f("channel %d: proxy request", c->self); 1126 1127 c->mux_rcb = channel_proxy_downstream; 1128 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1129 (r = sshbuf_put_u32(reply, rid)) != 0) 1130 fatal_fr(r, "reply"); 1131 1132 return 0; 1133 } 1134 1135 /* Channel callbacks fired on read/write from mux client fd */ 1136 static int 1137 mux_master_read_cb(struct ssh *ssh, Channel *c) 1138 { 1139 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1140 struct sshbuf *in = NULL, *out = NULL; 1141 u_int type, rid, i; 1142 int r, ret = -1; 1143 1144 if ((out = sshbuf_new()) == NULL) 1145 fatal_f("sshbuf_new"); 1146 1147 /* Setup ctx and */ 1148 if (c->mux_ctx == NULL) { 1149 state = xcalloc(1, sizeof(*state)); 1150 c->mux_ctx = state; 1151 channel_register_cleanup(ssh, c->self, 1152 mux_master_control_cleanup_cb, 0); 1153 1154 /* Send hello */ 1155 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1156 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1157 fatal_fr(r, "reply"); 1158 /* no extensions */ 1159 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1160 fatal_fr(r, "enqueue"); 1161 debug3_f("channel %d: hello sent", c->self); 1162 ret = 0; 1163 goto out; 1164 } 1165 1166 /* Channel code ensures that we receive whole packets */ 1167 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1168 malf: 1169 error_f("malformed message"); 1170 goto out; 1171 } 1172 1173 if ((r = sshbuf_get_u32(in, &type)) != 0) 1174 goto malf; 1175 debug3_f("channel %d packet type 0x%08x len %zu", c->self, 1176 type, sshbuf_len(in)); 1177 1178 if (type == MUX_MSG_HELLO) 1179 rid = 0; 1180 else { 1181 if (!state->hello_rcvd) { 1182 error_f("expected MUX_MSG_HELLO(0x%08x), " 1183 "received 0x%08x", MUX_MSG_HELLO, type); 1184 goto out; 1185 } 1186 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1187 goto malf; 1188 } 1189 1190 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1191 if (type == mux_master_handlers[i].type) { 1192 ret = mux_master_handlers[i].handler(ssh, rid, 1193 c, in, out); 1194 break; 1195 } 1196 } 1197 if (mux_master_handlers[i].handler == NULL) { 1198 error_f("unsupported mux message 0x%08x", type); 1199 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1200 ret = 0; 1201 } 1202 /* Enqueue reply packet */ 1203 if (sshbuf_len(out) != 0 && 1204 (r = sshbuf_put_stringb(c->output, out)) != 0) 1205 fatal_fr(r, "enqueue"); 1206 out: 1207 sshbuf_free(in); 1208 sshbuf_free(out); 1209 return ret; 1210 } 1211 1212 void 1213 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1214 { 1215 struct sshbuf *m; 1216 Channel *mux_chan; 1217 int r; 1218 1219 debug3_f("channel %d: exit message, exitval %d", c->self, exitval); 1220 1221 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1222 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1223 1224 /* Append exit message packet to control socket output queue */ 1225 if ((m = sshbuf_new()) == NULL) 1226 fatal_f("sshbuf_new"); 1227 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1228 (r = sshbuf_put_u32(m, c->self)) != 0 || 1229 (r = sshbuf_put_u32(m, exitval)) != 0 || 1230 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1231 fatal_fr(r, "reply"); 1232 sshbuf_free(m); 1233 } 1234 1235 void 1236 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1237 { 1238 struct sshbuf *m; 1239 Channel *mux_chan; 1240 int r; 1241 1242 debug3_f("channel %d: TTY alloc failed", c->self); 1243 1244 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1245 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1246 1247 /* Append exit message packet to control socket output queue */ 1248 if ((m = sshbuf_new()) == NULL) 1249 fatal_f("sshbuf_new"); 1250 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1251 (r = sshbuf_put_u32(m, c->self)) != 0 || 1252 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1253 fatal_fr(r, "reply"); 1254 sshbuf_free(m); 1255 } 1256 1257 /* Prepare a mux master to listen on a Unix domain socket. */ 1258 void 1259 muxserver_listen(struct ssh *ssh) 1260 { 1261 mode_t old_umask; 1262 char *orig_control_path = options.control_path; 1263 char rbuf[16+1]; 1264 u_int i, r; 1265 int oerrno; 1266 1267 if (options.control_path == NULL || 1268 options.control_master == SSHCTL_MASTER_NO) 1269 return; 1270 1271 debug("setting up multiplex master socket"); 1272 1273 /* 1274 * Use a temporary path before listen so we can pseudo-atomically 1275 * establish the listening socket in its final location to avoid 1276 * other processes racing in between bind() and listen() and hitting 1277 * an unready socket. 1278 */ 1279 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1280 r = arc4random_uniform(26+26+10); 1281 rbuf[i] = (r < 26) ? 'a' + r : 1282 (r < 26*2) ? 'A' + r - 26 : 1283 '0' + r - 26 - 26; 1284 } 1285 rbuf[sizeof(rbuf) - 1] = '\0'; 1286 options.control_path = NULL; 1287 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1288 debug3_f("temporary control path %s", options.control_path); 1289 1290 old_umask = umask(0177); 1291 muxserver_sock = unix_listener(options.control_path, 64, 0); 1292 oerrno = errno; 1293 umask(old_umask); 1294 if (muxserver_sock < 0) { 1295 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1296 error("ControlSocket %s already exists, " 1297 "disabling multiplexing", options.control_path); 1298 disable_mux_master: 1299 if (muxserver_sock != -1) { 1300 close(muxserver_sock); 1301 muxserver_sock = -1; 1302 } 1303 free(orig_control_path); 1304 free(options.control_path); 1305 options.control_path = NULL; 1306 options.control_master = SSHCTL_MASTER_NO; 1307 return; 1308 } else { 1309 /* unix_listener() logs the error */ 1310 cleanup_exit(255); 1311 } 1312 } 1313 1314 /* Now atomically "move" the mux socket into position */ 1315 if (link(options.control_path, orig_control_path) != 0) { 1316 if (errno != EEXIST) { 1317 fatal_f("link mux listener %s => %s: %s", 1318 options.control_path, orig_control_path, 1319 strerror(errno)); 1320 } 1321 error("ControlSocket %s already exists, disabling multiplexing", 1322 orig_control_path); 1323 unlink(options.control_path); 1324 goto disable_mux_master; 1325 } 1326 unlink(options.control_path); 1327 free(options.control_path); 1328 options.control_path = orig_control_path; 1329 1330 set_nonblock(muxserver_sock); 1331 1332 mux_listener_channel = channel_new(ssh, "mux listener", 1333 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1334 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1335 0, options.control_path, 1); 1336 mux_listener_channel->mux_rcb = mux_master_read_cb; 1337 debug3_f("mux listener channel %d fd %d", 1338 mux_listener_channel->self, mux_listener_channel->sock); 1339 } 1340 1341 /* Callback on open confirmation in mux master for a mux client session. */ 1342 static void 1343 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1344 { 1345 struct mux_session_confirm_ctx *cctx = arg; 1346 const char *display; 1347 Channel *c, *cc; 1348 int i, r; 1349 struct sshbuf *reply; 1350 1351 if (cctx == NULL) 1352 fatal_f("cctx == NULL"); 1353 if ((c = channel_by_id(ssh, id)) == NULL) 1354 fatal_f("no channel for id %d", id); 1355 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1356 fatal_f("channel %d lacks control channel %d", 1357 id, c->ctl_chan); 1358 if ((reply = sshbuf_new()) == NULL) 1359 fatal_f("sshbuf_new"); 1360 1361 if (!success) { 1362 debug3_f("sending failure reply"); 1363 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1364 "Session open refused by peer"); 1365 goto done; 1366 } 1367 1368 display = getenv("DISPLAY"); 1369 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1370 char *proto, *data; 1371 1372 /* Get reasonable local authentication information. */ 1373 if (client_x11_get_proto(ssh, display, options.xauth_location, 1374 options.forward_x11_trusted, options.forward_x11_timeout, 1375 &proto, &data) == 0) { 1376 /* Request forwarding with authentication spoofing. */ 1377 debug("Requesting X11 forwarding with authentication " 1378 "spoofing."); 1379 x11_request_forwarding_with_spoofing(ssh, id, 1380 display, proto, data, 1); 1381 /* XXX exit_on_forward_failure */ 1382 client_expect_confirm(ssh, id, "X11 forwarding", 1383 CONFIRM_WARN); 1384 } 1385 } 1386 1387 if (cctx->want_agent_fwd && options.forward_agent) { 1388 debug("Requesting authentication agent forwarding."); 1389 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1390 if ((r = sshpkt_send(ssh)) != 0) 1391 fatal_fr(r, "send"); 1392 } 1393 1394 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1395 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1396 1397 debug3_f("sending success reply"); 1398 /* prepare reply */ 1399 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1400 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1401 (r = sshbuf_put_u32(reply, c->self)) != 0) 1402 fatal_fr(r, "reply"); 1403 1404 done: 1405 /* Send reply */ 1406 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1407 fatal_fr(r, "enqueue"); 1408 sshbuf_free(reply); 1409 1410 if (cc->mux_pause <= 0) 1411 fatal_f("mux_pause %d", cc->mux_pause); 1412 cc->mux_pause = 0; /* start processing messages again */ 1413 c->open_confirm_ctx = NULL; 1414 sshbuf_free(cctx->cmd); 1415 free(cctx->term); 1416 if (cctx->env != NULL) { 1417 for (i = 0; cctx->env[i] != NULL; i++) 1418 free(cctx->env[i]); 1419 free(cctx->env); 1420 } 1421 free(cctx); 1422 } 1423 1424 /* ** Multiplexing client support */ 1425 1426 /* Exit signal handler */ 1427 static void 1428 control_client_sighandler(int signo) 1429 { 1430 muxclient_terminate = signo; 1431 } 1432 1433 /* 1434 * Relay signal handler - used to pass some signals from mux client to 1435 * mux master. 1436 */ 1437 static void 1438 control_client_sigrelay(int signo) 1439 { 1440 int save_errno = errno; 1441 1442 if (muxserver_pid > 1) 1443 kill(muxserver_pid, signo); 1444 1445 errno = save_errno; 1446 } 1447 1448 static int 1449 mux_client_read(int fd, struct sshbuf *b, size_t need, int timeout_ms) 1450 { 1451 size_t have; 1452 ssize_t len; 1453 u_char *p; 1454 int r; 1455 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 case EAGAIN: 1467 if (waitrfd(fd, &timeout_ms) == -1) 1468 return -1; /* timeout */ 1469 /* FALLTHROUGH */ 1470 case EINTR: 1471 continue; 1472 default: 1473 return -1; 1474 } 1475 } 1476 if (len == 0) { 1477 errno = EPIPE; 1478 return -1; 1479 } 1480 have += (size_t)len; 1481 } 1482 return 0; 1483 } 1484 1485 static int 1486 mux_client_write_packet(int fd, struct sshbuf *m) 1487 { 1488 struct sshbuf *queue; 1489 u_int have, need; 1490 int r, oerrno, len; 1491 const u_char *ptr; 1492 struct pollfd pfd; 1493 1494 pfd.fd = fd; 1495 pfd.events = POLLOUT; 1496 if ((queue = sshbuf_new()) == NULL) 1497 fatal_f("sshbuf_new"); 1498 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1499 fatal_fr(r, "enqueue"); 1500 1501 need = sshbuf_len(queue); 1502 ptr = sshbuf_ptr(queue); 1503 1504 for (have = 0; have < need; ) { 1505 if (muxclient_terminate) { 1506 sshbuf_free(queue); 1507 errno = EINTR; 1508 return -1; 1509 } 1510 len = write(fd, ptr + have, need - have); 1511 if (len == -1) { 1512 switch (errno) { 1513 case EAGAIN: 1514 (void)poll(&pfd, 1, -1); 1515 /* FALLTHROUGH */ 1516 case EINTR: 1517 continue; 1518 default: 1519 oerrno = errno; 1520 sshbuf_free(queue); 1521 errno = oerrno; 1522 return -1; 1523 } 1524 } 1525 if (len == 0) { 1526 sshbuf_free(queue); 1527 errno = EPIPE; 1528 return -1; 1529 } 1530 have += (u_int)len; 1531 } 1532 sshbuf_free(queue); 1533 return 0; 1534 } 1535 1536 static int 1537 mux_client_read_packet_timeout(int fd, struct sshbuf *m, int timeout_ms) 1538 { 1539 struct sshbuf *queue; 1540 size_t need, have; 1541 const u_char *ptr; 1542 int r, oerrno; 1543 1544 if ((queue = sshbuf_new()) == NULL) 1545 fatal_f("sshbuf_new"); 1546 if (mux_client_read(fd, queue, 4, timeout_ms) != 0) { 1547 if ((oerrno = errno) == EPIPE) 1548 debug3_f("read header failed: %s", 1549 strerror(errno)); 1550 sshbuf_free(queue); 1551 errno = oerrno; 1552 return -1; 1553 } 1554 need = PEEK_U32(sshbuf_ptr(queue)); 1555 if (mux_client_read(fd, queue, need, timeout_ms) != 0) { 1556 oerrno = errno; 1557 debug3_f("read body failed: %s", strerror(errno)); 1558 sshbuf_free(queue); 1559 errno = oerrno; 1560 return -1; 1561 } 1562 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1563 (r = sshbuf_put(m, ptr, have)) != 0) 1564 fatal_fr(r, "dequeue"); 1565 sshbuf_free(queue); 1566 return 0; 1567 } 1568 1569 static int 1570 mux_client_read_packet(int fd, struct sshbuf *m) 1571 { 1572 return mux_client_read_packet_timeout(fd, m, -1); 1573 } 1574 1575 static int 1576 mux_client_hello_exchange(int fd, int timeout_ms) 1577 { 1578 struct sshbuf *m; 1579 u_int type, ver; 1580 int r, ret = -1; 1581 1582 if ((m = sshbuf_new()) == NULL) 1583 fatal_f("sshbuf_new"); 1584 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1585 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1586 fatal_fr(r, "assemble hello"); 1587 /* no extensions */ 1588 1589 if (mux_client_write_packet(fd, m) != 0) { 1590 debug_f("write packet: %s", strerror(errno)); 1591 goto out; 1592 } 1593 1594 sshbuf_reset(m); 1595 1596 /* Read their HELLO */ 1597 if (mux_client_read_packet_timeout(fd, m, timeout_ms) != 0) { 1598 debug_f("read packet failed"); 1599 goto out; 1600 } 1601 1602 if ((r = sshbuf_get_u32(m, &type)) != 0) 1603 fatal_fr(r, "parse type"); 1604 if (type != MUX_MSG_HELLO) { 1605 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1606 goto out; 1607 } 1608 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1609 fatal_fr(r, "parse version"); 1610 if (ver != SSHMUX_VER) { 1611 error("Unsupported multiplexing protocol version %d " 1612 "(expected %d)", ver, SSHMUX_VER); 1613 goto out; 1614 } 1615 debug2_f("master version %u", ver); 1616 /* No extensions are presently defined */ 1617 while (sshbuf_len(m) > 0) { 1618 char *name = NULL; 1619 1620 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1621 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1622 error_fr(r, "parse extension"); 1623 goto out; 1624 } 1625 debug2("Unrecognised master extension \"%s\"", name); 1626 free(name); 1627 } 1628 /* success */ 1629 ret = 0; 1630 out: 1631 sshbuf_free(m); 1632 return ret; 1633 } 1634 1635 static u_int 1636 mux_client_request_alive(int fd) 1637 { 1638 struct sshbuf *m; 1639 char *e; 1640 u_int pid, type, rid; 1641 int r; 1642 1643 debug3_f("entering"); 1644 1645 if ((m = sshbuf_new()) == NULL) 1646 fatal_f("sshbuf_new"); 1647 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1648 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1649 fatal_fr(r, "assemble"); 1650 1651 if (mux_client_write_packet(fd, m) != 0) 1652 fatal_f("write packet: %s", strerror(errno)); 1653 1654 sshbuf_reset(m); 1655 1656 /* Read their reply */ 1657 if (mux_client_read_packet(fd, m) != 0) { 1658 sshbuf_free(m); 1659 return 0; 1660 } 1661 1662 if ((r = sshbuf_get_u32(m, &type)) != 0) 1663 fatal_fr(r, "parse type"); 1664 if (type != MUX_S_ALIVE) { 1665 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1666 fatal_fr(r, "parse error message"); 1667 fatal_f("master returned error: %s", e); 1668 } 1669 1670 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1671 fatal_fr(r, "parse remote ID"); 1672 if (rid != muxclient_request_id) 1673 fatal_f("out of sequence reply: my id %u theirs %u", 1674 muxclient_request_id, rid); 1675 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1676 fatal_fr(r, "parse PID"); 1677 sshbuf_free(m); 1678 1679 debug3_f("done pid = %u", pid); 1680 1681 muxclient_request_id++; 1682 1683 return pid; 1684 } 1685 1686 static void 1687 mux_client_request_terminate(int fd) 1688 { 1689 struct sshbuf *m; 1690 char *e; 1691 u_int type, rid; 1692 int r; 1693 1694 debug3_f("entering"); 1695 1696 if ((m = sshbuf_new()) == NULL) 1697 fatal_f("sshbuf_new"); 1698 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1699 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1700 fatal_fr(r, "request"); 1701 1702 if (mux_client_write_packet(fd, m) != 0) 1703 fatal_f("write packet: %s", strerror(errno)); 1704 1705 sshbuf_reset(m); 1706 1707 /* Read their reply */ 1708 if (mux_client_read_packet(fd, m) != 0) { 1709 /* Remote end exited already */ 1710 if (errno == EPIPE) { 1711 sshbuf_free(m); 1712 return; 1713 } 1714 fatal_f("read from master failed: %s", strerror(errno)); 1715 } 1716 1717 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1718 (r = sshbuf_get_u32(m, &rid)) != 0) 1719 fatal_fr(r, "parse"); 1720 if (rid != muxclient_request_id) 1721 fatal_f("out of sequence reply: my id %u theirs %u", 1722 muxclient_request_id, rid); 1723 switch (type) { 1724 case MUX_S_OK: 1725 break; 1726 case MUX_S_PERMISSION_DENIED: 1727 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1728 fatal_fr(r, "parse error message"); 1729 fatal("Master refused termination request: %s", e); 1730 case MUX_S_FAILURE: 1731 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1732 fatal_fr(r, "parse error message"); 1733 fatal_f("termination request failed: %s", e); 1734 default: 1735 fatal_f("unexpected response from master 0x%08x", type); 1736 } 1737 sshbuf_free(m); 1738 muxclient_request_id++; 1739 } 1740 1741 static int 1742 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1743 { 1744 struct sshbuf *m; 1745 char *e, *fwd_desc; 1746 const char *lhost, *chost; 1747 u_int type, rid; 1748 int r; 1749 1750 fwd_desc = format_forward(ftype, fwd); 1751 debug("Requesting %s %s", 1752 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1753 free(fwd_desc); 1754 1755 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1756 if (fwd->listen_path != NULL) 1757 lhost = fwd->listen_path; 1758 else if (fwd->listen_host == NULL) 1759 lhost = ""; 1760 else if (*fwd->listen_host == '\0') 1761 lhost = "*"; 1762 else 1763 lhost = fwd->listen_host; 1764 1765 if (fwd->connect_path != NULL) 1766 chost = fwd->connect_path; 1767 else if (fwd->connect_host == NULL) 1768 chost = ""; 1769 else 1770 chost = fwd->connect_host; 1771 1772 if ((m = sshbuf_new()) == NULL) 1773 fatal_f("sshbuf_new"); 1774 if ((r = sshbuf_put_u32(m, type)) != 0 || 1775 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1776 (r = sshbuf_put_u32(m, ftype)) != 0 || 1777 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1778 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1779 (r = sshbuf_put_cstring(m, chost)) != 0 || 1780 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1781 fatal_fr(r, "request"); 1782 1783 if (mux_client_write_packet(fd, m) != 0) 1784 fatal_f("write packet: %s", strerror(errno)); 1785 1786 sshbuf_reset(m); 1787 1788 /* Read their reply */ 1789 if (mux_client_read_packet(fd, m) != 0) { 1790 sshbuf_free(m); 1791 return -1; 1792 } 1793 1794 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1795 (r = sshbuf_get_u32(m, &rid)) != 0) 1796 fatal_fr(r, "parse"); 1797 if (rid != muxclient_request_id) 1798 fatal_f("out of sequence reply: my id %u theirs %u", 1799 muxclient_request_id, rid); 1800 1801 switch (type) { 1802 case MUX_S_OK: 1803 break; 1804 case MUX_S_REMOTE_PORT: 1805 if (cancel_flag) 1806 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1807 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1808 fatal_fr(r, "parse port"); 1809 verbose("Allocated port %u for remote forward to %s:%d", 1810 fwd->allocated_port, 1811 fwd->connect_host ? fwd->connect_host : "", 1812 fwd->connect_port); 1813 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1814 fprintf(stdout, "%i\n", fwd->allocated_port); 1815 break; 1816 case MUX_S_PERMISSION_DENIED: 1817 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1818 fatal_fr(r, "parse error message"); 1819 sshbuf_free(m); 1820 error("Master refused forwarding request: %s", e); 1821 return -1; 1822 case MUX_S_FAILURE: 1823 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1824 fatal_fr(r, "parse error message"); 1825 sshbuf_free(m); 1826 error_f("forwarding request failed: %s", e); 1827 return -1; 1828 default: 1829 fatal_f("unexpected response from master 0x%08x", type); 1830 } 1831 sshbuf_free(m); 1832 1833 muxclient_request_id++; 1834 return 0; 1835 } 1836 1837 static int 1838 mux_client_forwards(int fd, int cancel_flag) 1839 { 1840 int i, ret = 0; 1841 1842 debug3_f("%s forwardings: %d local, %d remote", 1843 cancel_flag ? "cancel" : "request", 1844 options.num_local_forwards, options.num_remote_forwards); 1845 1846 /* XXX ExitOnForwardingFailure */ 1847 for (i = 0; i < options.num_local_forwards; i++) { 1848 if (mux_client_forward(fd, cancel_flag, 1849 options.local_forwards[i].connect_port == 0 ? 1850 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1851 options.local_forwards + i) != 0) 1852 ret = -1; 1853 } 1854 for (i = 0; i < options.num_remote_forwards; i++) { 1855 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1856 options.remote_forwards + i) != 0) 1857 ret = -1; 1858 } 1859 return ret; 1860 } 1861 1862 static int 1863 mux_client_request_session(int fd) 1864 { 1865 struct sshbuf *m; 1866 char *e; 1867 const char *term = NULL; 1868 u_int i, echar, rid, sid, esid, exitval, type, exitval_seen; 1869 extern char **environ; 1870 int r, rawmode = 0; 1871 1872 debug3_f("entering"); 1873 1874 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1875 error_f("master alive request failed"); 1876 return -1; 1877 } 1878 1879 ssh_signal(SIGPIPE, SIG_IGN); 1880 1881 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 1882 fatal_f("stdfd_devnull failed"); 1883 1884 if ((term = lookup_env_in_list("TERM", options.setenv, 1885 options.num_setenv)) == NULL || *term == '\0') 1886 term = getenv("TERM"); 1887 1888 echar = 0xffffffff; 1889 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1890 echar = (u_int)options.escape_char; 1891 1892 if ((m = sshbuf_new()) == NULL) 1893 fatal_f("sshbuf_new"); 1894 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1895 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1896 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1897 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1898 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1899 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1900 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 || 1901 (r = sshbuf_put_u32(m, echar)) != 0 || 1902 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 || 1903 (r = sshbuf_put_stringb(m, command)) != 0) 1904 fatal_fr(r, "request"); 1905 1906 /* Pass environment */ 1907 if (options.num_send_env > 0 && environ != NULL) { 1908 for (i = 0; environ[i] != NULL; i++) { 1909 if (!env_permitted(environ[i])) 1910 continue; 1911 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1912 fatal_fr(r, "request sendenv"); 1913 } 1914 } 1915 for (i = 0; i < options.num_setenv; i++) { 1916 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1917 fatal_fr(r, "request setenv"); 1918 } 1919 1920 if (mux_client_write_packet(fd, m) != 0) 1921 fatal_f("write packet: %s", strerror(errno)); 1922 1923 /* Send the stdio file descriptors */ 1924 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1925 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1926 mm_send_fd(fd, STDERR_FILENO) == -1) 1927 fatal_f("send fds failed"); 1928 1929 debug3_f("session request sent"); 1930 1931 /* Read their reply */ 1932 sshbuf_reset(m); 1933 if (mux_client_read_packet(fd, m) != 0) { 1934 error_f("read from master failed: %s", strerror(errno)); 1935 sshbuf_free(m); 1936 return -1; 1937 } 1938 1939 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1940 (r = sshbuf_get_u32(m, &rid)) != 0) 1941 fatal_fr(r, "parse"); 1942 if (rid != muxclient_request_id) 1943 fatal_f("out of sequence reply: my id %u theirs %u", 1944 muxclient_request_id, rid); 1945 1946 switch (type) { 1947 case MUX_S_SESSION_OPENED: 1948 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1949 fatal_fr(r, "parse session ID"); 1950 debug_f("master session id: %u", sid); 1951 break; 1952 case MUX_S_PERMISSION_DENIED: 1953 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1954 fatal_fr(r, "parse error message"); 1955 error("Master refused session request: %s", e); 1956 sshbuf_free(m); 1957 return -1; 1958 case MUX_S_FAILURE: 1959 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1960 fatal_fr(r, "parse error message"); 1961 error_f("session request failed: %s", e); 1962 sshbuf_free(m); 1963 return -1; 1964 default: 1965 sshbuf_free(m); 1966 error_f("unexpected response from master 0x%08x", type); 1967 return -1; 1968 } 1969 muxclient_request_id++; 1970 1971 if (pledge("stdio proc tty", NULL) == -1) 1972 fatal_f("pledge(): %s", strerror(errno)); 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 if (options.fork_after_authentication) 1980 daemon(1, 1); 1981 else { 1982 rawmode = tty_flag; 1983 if (tty_flag) { 1984 enter_raw_mode( 1985 options.request_tty == REQUEST_TTY_FORCE); 1986 } 1987 } 1988 1989 /* 1990 * Stick around until the controlee closes the client_fd. 1991 * Before it does, it is expected to write an exit message. 1992 * This process must read the value and wait for the closure of 1993 * the client_fd; if this one closes early, the multiplex master will 1994 * terminate early too (possibly losing data). 1995 */ 1996 for (exitval = 255, exitval_seen = 0;;) { 1997 sshbuf_reset(m); 1998 if (mux_client_read_packet(fd, m) != 0) 1999 break; 2000 if ((r = sshbuf_get_u32(m, &type)) != 0) 2001 fatal_fr(r, "parse type"); 2002 switch (type) { 2003 case MUX_S_TTY_ALLOC_FAIL: 2004 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2005 fatal_fr(r, "parse session ID"); 2006 if (esid != sid) 2007 fatal_f("tty alloc fail on unknown session: " 2008 "my id %u theirs %u", sid, esid); 2009 leave_raw_mode(options.request_tty == 2010 REQUEST_TTY_FORCE); 2011 rawmode = 0; 2012 continue; 2013 case MUX_S_EXIT_MESSAGE: 2014 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2015 fatal_fr(r, "parse session ID"); 2016 if (esid != sid) 2017 fatal_f("exit on unknown session: " 2018 "my id %u theirs %u", sid, esid); 2019 if (exitval_seen) 2020 fatal_f("exitval sent twice"); 2021 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2022 fatal_fr(r, "parse exitval"); 2023 exitval_seen = 1; 2024 continue; 2025 default: 2026 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2027 fatal_fr(r, "parse error message"); 2028 fatal_f("master returned error: %s", e); 2029 } 2030 } 2031 2032 close(fd); 2033 if (rawmode) 2034 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2035 2036 if (muxclient_terminate) { 2037 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2038 exitval = 255; 2039 } else if (!exitval_seen) { 2040 debug2("Control master terminated unexpectedly"); 2041 exitval = 255; 2042 } else 2043 debug2("Received exit status from master %d", exitval); 2044 2045 if (tty_flag && options.log_level >= SYSLOG_LEVEL_INFO) 2046 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2047 2048 exit(exitval); 2049 } 2050 2051 static int 2052 mux_client_proxy(int fd) 2053 { 2054 struct sshbuf *m; 2055 char *e; 2056 u_int type, rid; 2057 int r; 2058 2059 if ((m = sshbuf_new()) == NULL) 2060 fatal_f("sshbuf_new"); 2061 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2062 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2063 fatal_fr(r, "request"); 2064 if (mux_client_write_packet(fd, m) != 0) 2065 fatal_f("write packet: %s", strerror(errno)); 2066 2067 sshbuf_reset(m); 2068 2069 /* Read their reply */ 2070 if (mux_client_read_packet(fd, m) != 0) { 2071 sshbuf_free(m); 2072 return 0; 2073 } 2074 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2075 (r = sshbuf_get_u32(m, &rid)) != 0) 2076 fatal_fr(r, "parse"); 2077 if (rid != muxclient_request_id) 2078 fatal_f("out of sequence reply: my id %u theirs %u", 2079 muxclient_request_id, rid); 2080 if (type != MUX_S_PROXY) { 2081 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2082 fatal_fr(r, "parse error message"); 2083 fatal_f("master returned error: %s", e); 2084 } 2085 sshbuf_free(m); 2086 2087 debug3_f("done"); 2088 muxclient_request_id++; 2089 return 0; 2090 } 2091 2092 static int 2093 mux_client_request_stdio_fwd(int fd) 2094 { 2095 struct sshbuf *m; 2096 char *e; 2097 u_int type, rid, sid; 2098 int r; 2099 2100 debug3_f("entering"); 2101 2102 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2103 error_f("master alive request failed"); 2104 return -1; 2105 } 2106 2107 ssh_signal(SIGPIPE, SIG_IGN); 2108 2109 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 2110 fatal_f("stdfd_devnull failed"); 2111 2112 if ((m = sshbuf_new()) == NULL) 2113 fatal_f("sshbuf_new"); 2114 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2115 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2116 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2117 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2118 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2119 fatal_fr(r, "request"); 2120 2121 if (mux_client_write_packet(fd, m) != 0) 2122 fatal_f("write packet: %s", strerror(errno)); 2123 2124 /* Send the stdio file descriptors */ 2125 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2126 mm_send_fd(fd, STDOUT_FILENO) == -1) 2127 fatal_f("send fds failed"); 2128 2129 if (pledge("stdio proc tty", NULL) == -1) 2130 fatal_f("pledge(): %s", strerror(errno)); 2131 2132 debug3_f("stdio forward request sent"); 2133 2134 /* Read their reply */ 2135 sshbuf_reset(m); 2136 2137 if (mux_client_read_packet(fd, m) != 0) { 2138 error_f("read from master failed: %s", strerror(errno)); 2139 sshbuf_free(m); 2140 return -1; 2141 } 2142 2143 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2144 (r = sshbuf_get_u32(m, &rid)) != 0) 2145 fatal_fr(r, "parse"); 2146 if (rid != muxclient_request_id) 2147 fatal_f("out of sequence reply: my id %u theirs %u", 2148 muxclient_request_id, rid); 2149 switch (type) { 2150 case MUX_S_SESSION_OPENED: 2151 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2152 fatal_fr(r, "parse session ID"); 2153 debug_f("master session id: %u", sid); 2154 break; 2155 case MUX_S_PERMISSION_DENIED: 2156 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2157 fatal_fr(r, "parse error message"); 2158 sshbuf_free(m); 2159 fatal("Master refused stdio forwarding request: %s", e); 2160 case MUX_S_FAILURE: 2161 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2162 fatal_fr(r, "parse error message"); 2163 sshbuf_free(m); 2164 fatal("Stdio forwarding request failed: %s", e); 2165 default: 2166 sshbuf_free(m); 2167 error_f("unexpected response from master 0x%08x", type); 2168 return -1; 2169 } 2170 muxclient_request_id++; 2171 2172 ssh_signal(SIGHUP, control_client_sighandler); 2173 ssh_signal(SIGINT, control_client_sighandler); 2174 ssh_signal(SIGTERM, control_client_sighandler); 2175 ssh_signal(SIGWINCH, control_client_sigrelay); 2176 2177 /* 2178 * Stick around until the controlee closes the client_fd. 2179 */ 2180 sshbuf_reset(m); 2181 if (mux_client_read_packet(fd, m) != 0) { 2182 if (errno == EPIPE || 2183 (errno == EINTR && muxclient_terminate != 0)) 2184 return 0; 2185 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2186 } 2187 fatal_f("master returned unexpected message %u", type); 2188 } 2189 2190 static void 2191 mux_client_request_stop_listening(int fd) 2192 { 2193 struct sshbuf *m; 2194 char *e; 2195 u_int type, rid; 2196 int r; 2197 2198 debug3_f("entering"); 2199 2200 if ((m = sshbuf_new()) == NULL) 2201 fatal_f("sshbuf_new"); 2202 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2203 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2204 fatal_fr(r, "request"); 2205 2206 if (mux_client_write_packet(fd, m) != 0) 2207 fatal_f("write packet: %s", strerror(errno)); 2208 2209 sshbuf_reset(m); 2210 2211 /* Read their reply */ 2212 if (mux_client_read_packet(fd, m) != 0) 2213 fatal_f("read from master failed: %s", strerror(errno)); 2214 2215 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2216 (r = sshbuf_get_u32(m, &rid)) != 0) 2217 fatal_fr(r, "parse"); 2218 if (rid != muxclient_request_id) 2219 fatal_f("out of sequence reply: my id %u theirs %u", 2220 muxclient_request_id, rid); 2221 2222 switch (type) { 2223 case MUX_S_OK: 2224 break; 2225 case MUX_S_PERMISSION_DENIED: 2226 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2227 fatal_fr(r, "parse error message"); 2228 fatal("Master refused stop listening request: %s", e); 2229 case MUX_S_FAILURE: 2230 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2231 fatal_fr(r, "parse error message"); 2232 fatal_f("stop listening request failed: %s", e); 2233 default: 2234 fatal_f("unexpected response from master 0x%08x", type); 2235 } 2236 sshbuf_free(m); 2237 muxclient_request_id++; 2238 } 2239 2240 /* Multiplex client main loop. */ 2241 int 2242 muxclient(const char *path) 2243 { 2244 struct sockaddr_un addr; 2245 int sock, timeout = options.connection_timeout, timeout_ms = -1; 2246 u_int pid; 2247 2248 if (muxclient_command == 0) { 2249 if (options.stdio_forward_host != NULL) 2250 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2251 else 2252 muxclient_command = SSHMUX_COMMAND_OPEN; 2253 } 2254 2255 switch (options.control_master) { 2256 case SSHCTL_MASTER_AUTO: 2257 case SSHCTL_MASTER_AUTO_ASK: 2258 debug("auto-mux: Trying existing master"); 2259 /* FALLTHROUGH */ 2260 case SSHCTL_MASTER_NO: 2261 break; 2262 default: 2263 return -1; 2264 } 2265 2266 memset(&addr, '\0', sizeof(addr)); 2267 addr.sun_family = AF_UNIX; 2268 2269 if (strlcpy(addr.sun_path, path, 2270 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2271 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2272 (unsigned int)sizeof(addr.sun_path)); 2273 2274 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2275 fatal_f("socket(): %s", strerror(errno)); 2276 2277 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2278 switch (muxclient_command) { 2279 case SSHMUX_COMMAND_OPEN: 2280 case SSHMUX_COMMAND_STDIO_FWD: 2281 break; 2282 default: 2283 fatal("Control socket connect(%.100s): %s", path, 2284 strerror(errno)); 2285 } 2286 if (errno == ECONNREFUSED && 2287 options.control_master != SSHCTL_MASTER_NO) { 2288 debug("Stale control socket %.100s, unlinking", path); 2289 unlink(path); 2290 } else if (errno == ENOENT) { 2291 debug("Control socket \"%.100s\" does not exist", path); 2292 } else { 2293 error("Control socket connect(%.100s): %s", path, 2294 strerror(errno)); 2295 } 2296 close(sock); 2297 return -1; 2298 } 2299 set_nonblock(sock); 2300 2301 /* Timeout on initial connection only. */ 2302 if (timeout > 0 && timeout < INT_MAX / 1000) 2303 timeout_ms = timeout * 1000; 2304 2305 if (mux_client_hello_exchange(sock, timeout_ms) != 0) { 2306 error_f("master hello exchange failed"); 2307 close(sock); 2308 return -1; 2309 } 2310 2311 switch (muxclient_command) { 2312 case SSHMUX_COMMAND_ALIVE_CHECK: 2313 if ((pid = mux_client_request_alive(sock)) == 0) 2314 fatal_f("master alive check failed"); 2315 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2316 exit(0); 2317 case SSHMUX_COMMAND_TERMINATE: 2318 mux_client_request_terminate(sock); 2319 if (options.log_level != SYSLOG_LEVEL_QUIET) 2320 fprintf(stderr, "Exit request sent.\r\n"); 2321 exit(0); 2322 case SSHMUX_COMMAND_FORWARD: 2323 if (mux_client_forwards(sock, 0) != 0) 2324 fatal_f("master forward request failed"); 2325 exit(0); 2326 case SSHMUX_COMMAND_OPEN: 2327 if (mux_client_forwards(sock, 0) != 0) { 2328 error_f("master forward request failed"); 2329 return -1; 2330 } 2331 mux_client_request_session(sock); 2332 return -1; 2333 case SSHMUX_COMMAND_STDIO_FWD: 2334 mux_client_request_stdio_fwd(sock); 2335 exit(0); 2336 case SSHMUX_COMMAND_STOP: 2337 mux_client_request_stop_listening(sock); 2338 if (options.log_level != SYSLOG_LEVEL_QUIET) 2339 fprintf(stderr, "Stop listening request sent.\r\n"); 2340 exit(0); 2341 case SSHMUX_COMMAND_CANCEL_FWD: 2342 if (mux_client_forwards(sock, 1) != 0) 2343 error_f("master cancel forward request failed"); 2344 exit(0); 2345 case SSHMUX_COMMAND_PROXY: 2346 mux_client_proxy(sock); 2347 return (sock); 2348 default: 2349 fatal("unrecognised muxclient_command %d", muxclient_command); 2350 } 2351 } 2352