1 /* $OpenBSD: mux.c,v 1.97 2023/06/20 23:59:33 djm Exp $ */ 2 /* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* ssh session multiplexing support */ 19 20 #include <sys/types.h> 21 #include <sys/queue.h> 22 #include <sys/stat.h> 23 #include <sys/socket.h> 24 #include <sys/un.h> 25 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <poll.h> 29 #include <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 59 /* from ssh.c */ 60 extern int tty_flag; 61 extern Options options; 62 extern char *host; 63 extern struct sshbuf *command; 64 extern volatile sig_atomic_t quit_pending; 65 66 /* Context for session open confirmation callback */ 67 struct mux_session_confirm_ctx { 68 u_int want_tty; 69 u_int want_subsys; 70 u_int want_x_fwd; 71 u_int want_agent_fwd; 72 struct sshbuf *cmd; 73 char *term; 74 struct termios tio; 75 char **env; 76 u_int rid; 77 }; 78 79 /* Context for stdio fwd open confirmation callback */ 80 struct mux_stdio_confirm_ctx { 81 u_int rid; 82 }; 83 84 /* Context for global channel callback */ 85 struct mux_channel_confirm_ctx { 86 u_int cid; /* channel id */ 87 u_int rid; /* request id */ 88 int fid; /* forward id */ 89 }; 90 91 /* fd to control socket */ 92 int muxserver_sock = -1; 93 94 /* client request id */ 95 u_int muxclient_request_id = 0; 96 97 /* Multiplexing control command */ 98 u_int muxclient_command = 0; 99 100 /* Set when signalled. */ 101 static volatile sig_atomic_t muxclient_terminate = 0; 102 103 /* PID of multiplex server */ 104 static u_int muxserver_pid = 0; 105 106 static Channel *mux_listener_channel = NULL; 107 108 struct mux_master_state { 109 int hello_rcvd; 110 }; 111 112 /* mux protocol messages */ 113 #define MUX_MSG_HELLO 0x00000001 114 #define MUX_C_NEW_SESSION 0x10000002 115 #define MUX_C_ALIVE_CHECK 0x10000004 116 #define MUX_C_TERMINATE 0x10000005 117 #define MUX_C_OPEN_FWD 0x10000006 118 #define MUX_C_CLOSE_FWD 0x10000007 119 #define MUX_C_NEW_STDIO_FWD 0x10000008 120 #define MUX_C_STOP_LISTENING 0x10000009 121 #define MUX_C_PROXY 0x1000000f 122 #define MUX_S_OK 0x80000001 123 #define MUX_S_PERMISSION_DENIED 0x80000002 124 #define MUX_S_FAILURE 0x80000003 125 #define MUX_S_EXIT_MESSAGE 0x80000004 126 #define MUX_S_ALIVE 0x80000005 127 #define MUX_S_SESSION_OPENED 0x80000006 128 #define MUX_S_REMOTE_PORT 0x80000007 129 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 130 #define MUX_S_PROXY 0x8000000f 131 132 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 133 #define MUX_FWD_LOCAL 1 134 #define MUX_FWD_REMOTE 2 135 #define MUX_FWD_DYNAMIC 3 136 137 static void mux_session_confirm(struct ssh *, int, int, void *); 138 static void mux_stdio_confirm(struct ssh *, int, int, void *); 139 140 static int mux_master_process_hello(struct ssh *, u_int, 141 Channel *, struct sshbuf *, struct sshbuf *); 142 static int mux_master_process_new_session(struct ssh *, u_int, 143 Channel *, struct sshbuf *, struct sshbuf *); 144 static int mux_master_process_alive_check(struct ssh *, u_int, 145 Channel *, struct sshbuf *, struct sshbuf *); 146 static int mux_master_process_terminate(struct ssh *, u_int, 147 Channel *, struct sshbuf *, struct sshbuf *); 148 static int mux_master_process_open_fwd(struct ssh *, u_int, 149 Channel *, struct sshbuf *, struct sshbuf *); 150 static int mux_master_process_close_fwd(struct ssh *, u_int, 151 Channel *, struct sshbuf *, struct sshbuf *); 152 static int mux_master_process_stdio_fwd(struct ssh *, u_int, 153 Channel *, struct sshbuf *, struct sshbuf *); 154 static int mux_master_process_stop_listening(struct ssh *, u_int, 155 Channel *, struct sshbuf *, struct sshbuf *); 156 static int mux_master_process_proxy(struct ssh *, u_int, 157 Channel *, struct sshbuf *, struct sshbuf *); 158 159 static const struct { 160 u_int type; 161 int (*handler)(struct ssh *, u_int, Channel *, 162 struct sshbuf *, struct sshbuf *); 163 } mux_master_handlers[] = { 164 { MUX_MSG_HELLO, mux_master_process_hello }, 165 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 166 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 167 { MUX_C_TERMINATE, mux_master_process_terminate }, 168 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 169 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 170 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 171 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 172 { MUX_C_PROXY, mux_master_process_proxy }, 173 { 0, NULL } 174 }; 175 176 /* Cleanup callback fired on closure of mux client _session_ channel */ 177 static void 178 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 179 { 180 Channel *cc, *c = channel_by_id(ssh, cid); 181 182 debug3_f("entering for channel %d", cid); 183 if (c == NULL) 184 fatal_f("channel_by_id(%i) == NULL", cid); 185 if (c->ctl_chan != -1) { 186 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 187 fatal_f("channel %d missing control channel %d", 188 c->self, c->ctl_chan); 189 c->ctl_chan = -1; 190 cc->remote_id = 0; 191 cc->have_remote_id = 0; 192 chan_rcvd_oclose(ssh, cc); 193 } 194 channel_cancel_cleanup(ssh, c->self); 195 } 196 197 /* Cleanup callback fired on closure of mux client _control_ channel */ 198 static void 199 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 200 { 201 Channel *sc, *c = channel_by_id(ssh, cid); 202 203 debug3_f("entering for channel %d", cid); 204 if (c == NULL) 205 fatal_f("channel_by_id(%i) == NULL", cid); 206 if (c->have_remote_id) { 207 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 208 fatal_f("channel %d missing session channel %u", 209 c->self, c->remote_id); 210 c->remote_id = 0; 211 c->have_remote_id = 0; 212 sc->ctl_chan = -1; 213 if (sc->type != SSH_CHANNEL_OPEN && 214 sc->type != SSH_CHANNEL_OPENING) { 215 debug2_f("channel %d: not open", sc->self); 216 chan_mark_dead(ssh, sc); 217 } else { 218 if (sc->istate == CHAN_INPUT_OPEN) 219 chan_read_failed(ssh, sc); 220 if (sc->ostate == CHAN_OUTPUT_OPEN) 221 chan_write_failed(ssh, sc); 222 } 223 } 224 channel_cancel_cleanup(ssh, c->self); 225 } 226 227 /* Check mux client environment variables before passing them to mux master. */ 228 static int 229 env_permitted(const char *env) 230 { 231 u_int i; 232 int ret; 233 char name[1024], *cp; 234 235 if ((cp = strchr(env, '=')) == NULL || cp == env) 236 return 0; 237 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 238 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 239 error_f("name '%.100s...' too long", env); 240 return 0; 241 } 242 243 for (i = 0; i < options.num_send_env; i++) 244 if (match_pattern(name, options.send_env[i])) 245 return 1; 246 247 return 0; 248 } 249 250 /* Mux master protocol message handlers */ 251 252 static int 253 mux_master_process_hello(struct ssh *ssh, u_int rid, 254 Channel *c, struct sshbuf *m, struct sshbuf *reply) 255 { 256 u_int ver; 257 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 258 int r; 259 260 if (state == NULL) 261 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 262 if (state->hello_rcvd) { 263 error_f("HELLO received twice"); 264 return -1; 265 } 266 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 267 error_fr(r, "parse"); 268 return -1; 269 } 270 if (ver != SSHMUX_VER) { 271 error_f("unsupported multiplexing protocol version %u " 272 "(expected %u)", ver, SSHMUX_VER); 273 return -1; 274 } 275 debug2_f("channel %d client version %u", c->self, ver); 276 277 /* No extensions are presently defined */ 278 while (sshbuf_len(m) > 0) { 279 char *name = NULL; 280 size_t value_len = 0; 281 282 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 283 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 284 error_fr(r, "parse extension"); 285 return -1; 286 } 287 debug2_f("Unrecognised extension \"%s\" length %zu", 288 name, value_len); 289 free(name); 290 } 291 state->hello_rcvd = 1; 292 return 0; 293 } 294 295 /* Enqueue a "ok" response to the reply buffer */ 296 static void 297 reply_ok(struct sshbuf *reply, u_int rid) 298 { 299 int r; 300 301 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 302 (r = sshbuf_put_u32(reply, rid)) != 0) 303 fatal_fr(r, "reply"); 304 } 305 306 /* Enqueue an error response to the reply buffer */ 307 static void 308 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 309 { 310 int r; 311 312 if ((r = sshbuf_put_u32(reply, type)) != 0 || 313 (r = sshbuf_put_u32(reply, rid)) != 0 || 314 (r = sshbuf_put_cstring(reply, msg)) != 0) 315 fatal_fr(r, "reply"); 316 } 317 318 static int 319 mux_master_process_new_session(struct ssh *ssh, u_int rid, 320 Channel *c, struct sshbuf *m, struct sshbuf *reply) 321 { 322 Channel *nc; 323 struct mux_session_confirm_ctx *cctx; 324 char *cmd, *cp; 325 u_int i, j, env_len, escape_char, window, packetmax; 326 int r, new_fd[3]; 327 328 /* Reply for SSHMUX_COMMAND_OPEN */ 329 cctx = xcalloc(1, sizeof(*cctx)); 330 cctx->term = NULL; 331 cctx->rid = rid; 332 cmd = NULL; 333 cctx->env = NULL; 334 env_len = 0; 335 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 336 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 337 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 338 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 339 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 340 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 341 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 342 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 343 malf: 344 free(cmd); 345 for (j = 0; j < env_len; j++) 346 free(cctx->env[j]); 347 free(cctx->env); 348 free(cctx->term); 349 free(cctx); 350 error_f("malformed message"); 351 return -1; 352 } 353 354 #define MUX_MAX_ENV_VARS 4096 355 while (sshbuf_len(m) > 0) { 356 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 357 goto malf; 358 if (!env_permitted(cp)) { 359 free(cp); 360 continue; 361 } 362 cctx->env = xreallocarray(cctx->env, env_len + 2, 363 sizeof(*cctx->env)); 364 cctx->env[env_len++] = cp; 365 cctx->env[env_len] = NULL; 366 if (env_len > MUX_MAX_ENV_VARS) { 367 error_f(">%d environment variables received, " 368 "ignoring additional", MUX_MAX_ENV_VARS); 369 break; 370 } 371 } 372 373 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 374 "term \"%s\", cmd \"%s\", env %u", c->self, 375 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 376 cctx->want_subsys, cctx->term, cmd, env_len); 377 378 if ((cctx->cmd = sshbuf_new()) == NULL) 379 fatal_f("sshbuf_new"); 380 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 381 fatal_fr(r, "sshbuf_put"); 382 free(cmd); 383 cmd = NULL; 384 385 /* Gather fds from client */ 386 for(i = 0; i < 3; i++) { 387 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 388 error_f("failed to receive fd %d from client", i); 389 for (j = 0; j < i; j++) 390 close(new_fd[j]); 391 for (j = 0; j < env_len; j++) 392 free(cctx->env[j]); 393 free(cctx->env); 394 free(cctx->term); 395 sshbuf_free(cctx->cmd); 396 free(cctx); 397 reply_error(reply, MUX_S_FAILURE, rid, 398 "did not receive file descriptors"); 399 return -1; 400 } 401 } 402 403 debug3_f("got fds stdin %d, stdout %d, stderr %d", 404 new_fd[0], new_fd[1], new_fd[2]); 405 406 /* XXX support multiple child sessions in future */ 407 if (c->have_remote_id) { 408 debug2_f("session already open"); 409 reply_error(reply, MUX_S_FAILURE, rid, 410 "Multiple sessions not supported"); 411 cleanup: 412 close(new_fd[0]); 413 close(new_fd[1]); 414 close(new_fd[2]); 415 free(cctx->term); 416 if (env_len != 0) { 417 for (i = 0; i < env_len; i++) 418 free(cctx->env[i]); 419 free(cctx->env); 420 } 421 sshbuf_free(cctx->cmd); 422 free(cctx); 423 return 0; 424 } 425 426 if (options.control_master == SSHCTL_MASTER_ASK || 427 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 428 if (!ask_permission("Allow shared connection to %s? ", host)) { 429 debug2_f("session refused by user"); 430 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 431 "Permission denied"); 432 goto cleanup; 433 } 434 } 435 436 /* Try to pick up ttymodes from client before it goes raw */ 437 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 438 error_f("tcgetattr: %s", strerror(errno)); 439 440 window = CHAN_SES_WINDOW_DEFAULT; 441 packetmax = CHAN_SES_PACKET_DEFAULT; 442 if (cctx->want_tty) { 443 window >>= 1; 444 packetmax >>= 1; 445 } 446 447 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 448 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 449 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO); 450 451 nc->ctl_chan = c->self; /* link session -> control channel */ 452 c->remote_id = nc->self; /* link control -> session channel */ 453 c->have_remote_id = 1; 454 455 if (cctx->want_tty && escape_char != 0xffffffff) { 456 channel_register_filter(ssh, nc->self, 457 client_simple_escape_filter, NULL, 458 client_filter_cleanup, 459 client_new_escape_filter_ctx((int)escape_char)); 460 } 461 462 debug2_f("channel_new: %d linked to control channel %d", 463 nc->self, nc->ctl_chan); 464 465 channel_send_open(ssh, nc->self); 466 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 467 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 468 channel_register_cleanup(ssh, nc->self, 469 mux_master_session_cleanup_cb, 1); 470 471 /* reply is deferred, sent by mux_session_confirm */ 472 return 0; 473 } 474 475 static int 476 mux_master_process_alive_check(struct ssh *ssh, u_int rid, 477 Channel *c, struct sshbuf *m, struct sshbuf *reply) 478 { 479 int r; 480 481 debug2_f("channel %d: alive check", c->self); 482 483 /* prepare reply */ 484 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 485 (r = sshbuf_put_u32(reply, rid)) != 0 || 486 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 487 fatal_fr(r, "reply"); 488 489 return 0; 490 } 491 492 static int 493 mux_master_process_terminate(struct ssh *ssh, u_int rid, 494 Channel *c, struct sshbuf *m, struct sshbuf *reply) 495 { 496 debug2_f("channel %d: terminate request", c->self); 497 498 if (options.control_master == SSHCTL_MASTER_ASK || 499 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 500 if (!ask_permission("Terminate shared connection to %s? ", 501 host)) { 502 debug2_f("termination refused by user"); 503 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 504 "Permission denied"); 505 return 0; 506 } 507 } 508 509 quit_pending = 1; 510 reply_ok(reply, rid); 511 /* XXX exit happens too soon - message never makes it to client */ 512 return 0; 513 } 514 515 static char * 516 format_forward(u_int ftype, struct Forward *fwd) 517 { 518 char *ret; 519 520 switch (ftype) { 521 case MUX_FWD_LOCAL: 522 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 523 (fwd->listen_path != NULL) ? fwd->listen_path : 524 (fwd->listen_host == NULL) ? 525 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 526 fwd->listen_host, fwd->listen_port, 527 (fwd->connect_path != NULL) ? fwd->connect_path : 528 fwd->connect_host, fwd->connect_port); 529 break; 530 case MUX_FWD_DYNAMIC: 531 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 532 (fwd->listen_host == NULL) ? 533 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 534 fwd->listen_host, fwd->listen_port); 535 break; 536 case MUX_FWD_REMOTE: 537 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 538 (fwd->listen_path != NULL) ? fwd->listen_path : 539 (fwd->listen_host == NULL) ? 540 "LOCALHOST" : fwd->listen_host, 541 fwd->listen_port, 542 (fwd->connect_path != NULL) ? fwd->connect_path : 543 fwd->connect_host, fwd->connect_port); 544 break; 545 default: 546 fatal_f("unknown forward type %u", ftype); 547 } 548 return ret; 549 } 550 551 static int 552 compare_host(const char *a, const char *b) 553 { 554 if (a == NULL && b == NULL) 555 return 1; 556 if (a == NULL || b == NULL) 557 return 0; 558 return strcmp(a, b) == 0; 559 } 560 561 static int 562 compare_forward(struct Forward *a, struct Forward *b) 563 { 564 if (!compare_host(a->listen_host, b->listen_host)) 565 return 0; 566 if (!compare_host(a->listen_path, b->listen_path)) 567 return 0; 568 if (a->listen_port != b->listen_port) 569 return 0; 570 if (!compare_host(a->connect_host, b->connect_host)) 571 return 0; 572 if (!compare_host(a->connect_path, b->connect_path)) 573 return 0; 574 if (a->connect_port != b->connect_port) 575 return 0; 576 577 return 1; 578 } 579 580 static void 581 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 582 { 583 struct mux_channel_confirm_ctx *fctx = ctxt; 584 char *failmsg = NULL; 585 struct Forward *rfwd; 586 Channel *c; 587 struct sshbuf *out; 588 u_int port; 589 int r; 590 591 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 592 /* no channel for reply */ 593 error_f("unknown channel"); 594 return; 595 } 596 if ((out = sshbuf_new()) == NULL) 597 fatal_f("sshbuf_new"); 598 if (fctx->fid >= options.num_remote_forwards || 599 (options.remote_forwards[fctx->fid].connect_path == NULL && 600 options.remote_forwards[fctx->fid].connect_host == NULL)) { 601 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 602 goto fail; 603 } 604 rfwd = &options.remote_forwards[fctx->fid]; 605 debug_f("%s for: listen %d, connect %s:%d", 606 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 607 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 608 rfwd->connect_host, rfwd->connect_port); 609 if (type == SSH2_MSG_REQUEST_SUCCESS) { 610 if (rfwd->listen_port == 0) { 611 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 612 fatal_fr(r, "parse port"); 613 if (port > 65535) { 614 fatal("Invalid allocated port %u for " 615 "mux remote forward to %s:%d", port, 616 rfwd->connect_host, rfwd->connect_port); 617 } 618 rfwd->allocated_port = (int)port; 619 debug("Allocated port %u for mux remote forward" 620 " to %s:%d", rfwd->allocated_port, 621 rfwd->connect_host, rfwd->connect_port); 622 if ((r = sshbuf_put_u32(out, 623 MUX_S_REMOTE_PORT)) != 0 || 624 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 625 (r = sshbuf_put_u32(out, 626 rfwd->allocated_port)) != 0) 627 fatal_fr(r, "reply"); 628 channel_update_permission(ssh, rfwd->handle, 629 rfwd->allocated_port); 630 } else { 631 reply_ok(out, fctx->rid); 632 } 633 goto out; 634 } else { 635 if (rfwd->listen_port == 0) 636 channel_update_permission(ssh, rfwd->handle, -1); 637 if (rfwd->listen_path != NULL) 638 xasprintf(&failmsg, "remote port forwarding failed for " 639 "listen path %s", rfwd->listen_path); 640 else 641 xasprintf(&failmsg, "remote port forwarding failed for " 642 "listen port %d", rfwd->listen_port); 643 644 debug2_f("clearing registered forwarding for listen %d, " 645 "connect %s:%d", rfwd->listen_port, 646 rfwd->connect_path ? rfwd->connect_path : 647 rfwd->connect_host, rfwd->connect_port); 648 649 free(rfwd->listen_host); 650 free(rfwd->listen_path); 651 free(rfwd->connect_host); 652 free(rfwd->connect_path); 653 memset(rfwd, 0, sizeof(*rfwd)); 654 } 655 fail: 656 error_f("%s", failmsg); 657 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 658 free(failmsg); 659 out: 660 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 661 fatal_fr(r, "enqueue"); 662 sshbuf_free(out); 663 if (c->mux_pause <= 0) 664 fatal_f("mux_pause %d", c->mux_pause); 665 c->mux_pause = 0; /* start processing messages again */ 666 } 667 668 static int 669 mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 670 Channel *c, struct sshbuf *m, struct sshbuf *reply) 671 { 672 struct Forward fwd; 673 char *fwd_desc = NULL; 674 char *listen_addr, *connect_addr; 675 u_int ftype; 676 u_int lport, cport; 677 int r, i, ret = 0, freefwd = 1; 678 679 memset(&fwd, 0, sizeof(fwd)); 680 681 /* XXX - lport/cport check redundant */ 682 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 683 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 684 (r = sshbuf_get_u32(m, &lport)) != 0 || 685 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 686 (r = sshbuf_get_u32(m, &cport)) != 0 || 687 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 688 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 689 error_f("malformed message"); 690 ret = -1; 691 goto out; 692 } 693 if (*listen_addr == '\0') { 694 free(listen_addr); 695 listen_addr = NULL; 696 } 697 if (*connect_addr == '\0') { 698 free(connect_addr); 699 connect_addr = NULL; 700 } 701 702 memset(&fwd, 0, sizeof(fwd)); 703 fwd.listen_port = lport; 704 if (fwd.listen_port == PORT_STREAMLOCAL) 705 fwd.listen_path = listen_addr; 706 else 707 fwd.listen_host = listen_addr; 708 fwd.connect_port = cport; 709 if (fwd.connect_port == PORT_STREAMLOCAL) 710 fwd.connect_path = connect_addr; 711 else 712 fwd.connect_host = connect_addr; 713 714 debug2_f("channel %d: request %s", c->self, 715 (fwd_desc = format_forward(ftype, &fwd))); 716 717 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 718 ftype != MUX_FWD_DYNAMIC) { 719 logit_f("invalid forwarding type %u", ftype); 720 invalid: 721 free(listen_addr); 722 free(connect_addr); 723 reply_error(reply, MUX_S_FAILURE, rid, 724 "Invalid forwarding request"); 725 return 0; 726 } 727 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 728 logit_f("streamlocal and dynamic forwards " 729 "are mutually exclusive"); 730 goto invalid; 731 } 732 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 733 logit_f("invalid listen port %u", fwd.listen_port); 734 goto invalid; 735 } 736 if ((fwd.connect_port != PORT_STREAMLOCAL && 737 fwd.connect_port >= 65536) || 738 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 739 fwd.connect_port == 0)) { 740 logit_f("invalid connect port %u", 741 fwd.connect_port); 742 goto invalid; 743 } 744 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 745 fwd.connect_path == NULL) { 746 logit_f("missing connect host"); 747 goto invalid; 748 } 749 750 /* Skip forwards that have already been requested */ 751 switch (ftype) { 752 case MUX_FWD_LOCAL: 753 case MUX_FWD_DYNAMIC: 754 for (i = 0; i < options.num_local_forwards; i++) { 755 if (compare_forward(&fwd, 756 options.local_forwards + i)) { 757 exists: 758 debug2_f("found existing forwarding"); 759 reply_ok(reply, rid); 760 goto out; 761 } 762 } 763 break; 764 case MUX_FWD_REMOTE: 765 for (i = 0; i < options.num_remote_forwards; i++) { 766 if (!compare_forward(&fwd, options.remote_forwards + i)) 767 continue; 768 if (fwd.listen_port != 0) 769 goto exists; 770 debug2_f("found allocated port"); 771 if ((r = sshbuf_put_u32(reply, 772 MUX_S_REMOTE_PORT)) != 0 || 773 (r = sshbuf_put_u32(reply, rid)) != 0 || 774 (r = sshbuf_put_u32(reply, 775 options.remote_forwards[i].allocated_port)) != 0) 776 fatal_fr(r, "reply FWD_REMOTE"); 777 goto out; 778 } 779 break; 780 } 781 782 if (options.control_master == SSHCTL_MASTER_ASK || 783 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 784 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 785 debug2_f("forwarding refused by user"); 786 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 787 "Permission denied"); 788 goto out; 789 } 790 } 791 792 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 793 if (!channel_setup_local_fwd_listener(ssh, &fwd, 794 &options.fwd_opts)) { 795 fail: 796 logit_f("requested %s failed", fwd_desc); 797 reply_error(reply, MUX_S_FAILURE, rid, 798 "Port forwarding failed"); 799 goto out; 800 } 801 add_local_forward(&options, &fwd); 802 freefwd = 0; 803 } else { 804 struct mux_channel_confirm_ctx *fctx; 805 806 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 807 if (fwd.handle < 0) 808 goto fail; 809 add_remote_forward(&options, &fwd); 810 fctx = xcalloc(1, sizeof(*fctx)); 811 fctx->cid = c->self; 812 fctx->rid = rid; 813 fctx->fid = options.num_remote_forwards - 1; 814 client_register_global_confirm(mux_confirm_remote_forward, 815 fctx); 816 freefwd = 0; 817 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 818 /* delayed reply in mux_confirm_remote_forward */ 819 goto out; 820 } 821 reply_ok(reply, rid); 822 out: 823 free(fwd_desc); 824 if (freefwd) { 825 free(fwd.listen_host); 826 free(fwd.listen_path); 827 free(fwd.connect_host); 828 free(fwd.connect_path); 829 } 830 return ret; 831 } 832 833 static int 834 mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 835 Channel *c, struct sshbuf *m, struct sshbuf *reply) 836 { 837 struct Forward fwd, *found_fwd; 838 char *fwd_desc = NULL; 839 const char *error_reason = NULL; 840 char *listen_addr = NULL, *connect_addr = NULL; 841 u_int ftype; 842 int r, i, ret = 0; 843 u_int lport, cport; 844 845 memset(&fwd, 0, sizeof(fwd)); 846 847 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 848 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 849 (r = sshbuf_get_u32(m, &lport)) != 0 || 850 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 851 (r = sshbuf_get_u32(m, &cport)) != 0 || 852 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 853 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 854 error_f("malformed message"); 855 ret = -1; 856 goto out; 857 } 858 859 if (*listen_addr == '\0') { 860 free(listen_addr); 861 listen_addr = NULL; 862 } 863 if (*connect_addr == '\0') { 864 free(connect_addr); 865 connect_addr = NULL; 866 } 867 868 memset(&fwd, 0, sizeof(fwd)); 869 fwd.listen_port = lport; 870 if (fwd.listen_port == PORT_STREAMLOCAL) 871 fwd.listen_path = listen_addr; 872 else 873 fwd.listen_host = listen_addr; 874 fwd.connect_port = cport; 875 if (fwd.connect_port == PORT_STREAMLOCAL) 876 fwd.connect_path = connect_addr; 877 else 878 fwd.connect_host = connect_addr; 879 880 debug2_f("channel %d: request cancel %s", c->self, 881 (fwd_desc = format_forward(ftype, &fwd))); 882 883 /* make sure this has been requested */ 884 found_fwd = NULL; 885 switch (ftype) { 886 case MUX_FWD_LOCAL: 887 case MUX_FWD_DYNAMIC: 888 for (i = 0; i < options.num_local_forwards; i++) { 889 if (compare_forward(&fwd, 890 options.local_forwards + i)) { 891 found_fwd = options.local_forwards + i; 892 break; 893 } 894 } 895 break; 896 case MUX_FWD_REMOTE: 897 for (i = 0; i < options.num_remote_forwards; i++) { 898 if (compare_forward(&fwd, 899 options.remote_forwards + i)) { 900 found_fwd = options.remote_forwards + i; 901 break; 902 } 903 } 904 break; 905 } 906 907 if (found_fwd == NULL) 908 error_reason = "port not forwarded"; 909 else if (ftype == MUX_FWD_REMOTE) { 910 /* 911 * This shouldn't fail unless we confused the host/port 912 * between options.remote_forwards and permitted_opens. 913 * However, for dynamic allocated listen ports we need 914 * to use the actual listen port. 915 */ 916 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 917 error_reason = "port not in permitted opens"; 918 } else { /* local and dynamic forwards */ 919 /* Ditto */ 920 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 921 &options.fwd_opts) == -1) 922 error_reason = "port not found"; 923 } 924 925 if (error_reason != NULL) 926 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 927 else { 928 reply_ok(reply, rid); 929 free(found_fwd->listen_host); 930 free(found_fwd->listen_path); 931 free(found_fwd->connect_host); 932 free(found_fwd->connect_path); 933 found_fwd->listen_host = found_fwd->connect_host = NULL; 934 found_fwd->listen_path = found_fwd->connect_path = NULL; 935 found_fwd->listen_port = found_fwd->connect_port = 0; 936 } 937 out: 938 free(fwd_desc); 939 free(listen_addr); 940 free(connect_addr); 941 942 return ret; 943 } 944 945 static int 946 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 947 Channel *c, struct sshbuf *m, struct sshbuf *reply) 948 { 949 Channel *nc; 950 char *chost = NULL; 951 u_int _cport, i, j; 952 int ok = 0, cport, r, new_fd[2]; 953 struct mux_stdio_confirm_ctx *cctx; 954 955 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 956 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 957 (r = sshbuf_get_u32(m, &_cport)) != 0) { 958 free(chost); 959 error_f("malformed message"); 960 return -1; 961 } 962 if (_cport == (u_int)PORT_STREAMLOCAL) 963 cport = PORT_STREAMLOCAL; 964 else if (_cport <= INT_MAX) 965 cport = (int)_cport; 966 else { 967 free(chost); 968 error_f("invalid port 0x%x", _cport); 969 return -1; 970 } 971 972 debug2_f("channel %d: stdio fwd to %s:%d", c->self, chost, cport); 973 974 /* Gather fds from client */ 975 for(i = 0; i < 2; i++) { 976 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 977 error_f("failed to receive fd %d from client", i); 978 for (j = 0; j < i; j++) 979 close(new_fd[j]); 980 free(chost); 981 982 /* prepare reply */ 983 reply_error(reply, MUX_S_FAILURE, rid, 984 "did not receive file descriptors"); 985 return -1; 986 } 987 } 988 989 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 990 991 /* XXX support multiple child sessions in future */ 992 if (c->have_remote_id) { 993 debug2_f("session already open"); 994 reply_error(reply, MUX_S_FAILURE, rid, 995 "Multiple sessions not supported"); 996 cleanup: 997 close(new_fd[0]); 998 close(new_fd[1]); 999 free(chost); 1000 return 0; 1001 } 1002 1003 if (options.control_master == SSHCTL_MASTER_ASK || 1004 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1005 if (cport == PORT_STREAMLOCAL) { 1006 ok = ask_permission("Allow forward to path %s", chost); 1007 } else { 1008 ok = ask_permission("Allow forward to [%s]:%d? ", 1009 chost, cport); 1010 } 1011 if (!ok) { 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 case EAGAIN: 1469 (void)poll(&pfd, 1, -1); 1470 /* FALLTHROUGH */ 1471 case EINTR: 1472 continue; 1473 default: 1474 return -1; 1475 } 1476 } 1477 if (len == 0) { 1478 errno = EPIPE; 1479 return -1; 1480 } 1481 have += (size_t)len; 1482 } 1483 return 0; 1484 } 1485 1486 static int 1487 mux_client_write_packet(int fd, struct sshbuf *m) 1488 { 1489 struct sshbuf *queue; 1490 u_int have, need; 1491 int r, oerrno, len; 1492 const u_char *ptr; 1493 struct pollfd pfd; 1494 1495 pfd.fd = fd; 1496 pfd.events = POLLOUT; 1497 if ((queue = sshbuf_new()) == NULL) 1498 fatal_f("sshbuf_new"); 1499 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1500 fatal_fr(r, "enqueue"); 1501 1502 need = sshbuf_len(queue); 1503 ptr = sshbuf_ptr(queue); 1504 1505 for (have = 0; have < need; ) { 1506 if (muxclient_terminate) { 1507 sshbuf_free(queue); 1508 errno = EINTR; 1509 return -1; 1510 } 1511 len = write(fd, ptr + have, need - have); 1512 if (len == -1) { 1513 switch (errno) { 1514 case EAGAIN: 1515 (void)poll(&pfd, 1, -1); 1516 /* FALLTHROUGH */ 1517 case EINTR: 1518 continue; 1519 default: 1520 oerrno = errno; 1521 sshbuf_free(queue); 1522 errno = oerrno; 1523 return -1; 1524 } 1525 } 1526 if (len == 0) { 1527 sshbuf_free(queue); 1528 errno = EPIPE; 1529 return -1; 1530 } 1531 have += (u_int)len; 1532 } 1533 sshbuf_free(queue); 1534 return 0; 1535 } 1536 1537 static int 1538 mux_client_read_packet(int fd, struct sshbuf *m) 1539 { 1540 struct sshbuf *queue; 1541 size_t need, have; 1542 const u_char *ptr; 1543 int r, oerrno; 1544 1545 if ((queue = sshbuf_new()) == NULL) 1546 fatal_f("sshbuf_new"); 1547 if (mux_client_read(fd, queue, 4) != 0) { 1548 if ((oerrno = errno) == EPIPE) 1549 debug3_f("read header failed: %s", 1550 strerror(errno)); 1551 sshbuf_free(queue); 1552 errno = oerrno; 1553 return -1; 1554 } 1555 need = PEEK_U32(sshbuf_ptr(queue)); 1556 if (mux_client_read(fd, queue, need) != 0) { 1557 oerrno = errno; 1558 debug3_f("read body failed: %s", strerror(errno)); 1559 sshbuf_free(queue); 1560 errno = oerrno; 1561 return -1; 1562 } 1563 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1564 (r = sshbuf_put(m, ptr, have)) != 0) 1565 fatal_fr(r, "dequeue"); 1566 sshbuf_free(queue); 1567 return 0; 1568 } 1569 1570 static int 1571 mux_client_hello_exchange(int fd) 1572 { 1573 struct sshbuf *m; 1574 u_int type, ver; 1575 int r, ret = -1; 1576 1577 if ((m = sshbuf_new()) == NULL) 1578 fatal_f("sshbuf_new"); 1579 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1580 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1581 fatal_fr(r, "assemble hello"); 1582 /* no extensions */ 1583 1584 if (mux_client_write_packet(fd, m) != 0) { 1585 debug_f("write packet: %s", strerror(errno)); 1586 goto out; 1587 } 1588 1589 sshbuf_reset(m); 1590 1591 /* Read their HELLO */ 1592 if (mux_client_read_packet(fd, m) != 0) { 1593 debug_f("read packet failed"); 1594 goto out; 1595 } 1596 1597 if ((r = sshbuf_get_u32(m, &type)) != 0) 1598 fatal_fr(r, "parse type"); 1599 if (type != MUX_MSG_HELLO) { 1600 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1601 goto out; 1602 } 1603 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1604 fatal_fr(r, "parse version"); 1605 if (ver != SSHMUX_VER) { 1606 error("Unsupported multiplexing protocol version %d " 1607 "(expected %d)", ver, SSHMUX_VER); 1608 goto out; 1609 } 1610 debug2_f("master version %u", ver); 1611 /* No extensions are presently defined */ 1612 while (sshbuf_len(m) > 0) { 1613 char *name = NULL; 1614 1615 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1616 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1617 error_fr(r, "parse extension"); 1618 goto out; 1619 } 1620 debug2("Unrecognised master extension \"%s\"", name); 1621 free(name); 1622 } 1623 /* success */ 1624 ret = 0; 1625 out: 1626 sshbuf_free(m); 1627 return ret; 1628 } 1629 1630 static u_int 1631 mux_client_request_alive(int fd) 1632 { 1633 struct sshbuf *m; 1634 char *e; 1635 u_int pid, type, rid; 1636 int r; 1637 1638 debug3_f("entering"); 1639 1640 if ((m = sshbuf_new()) == NULL) 1641 fatal_f("sshbuf_new"); 1642 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1643 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1644 fatal_fr(r, "assemble"); 1645 1646 if (mux_client_write_packet(fd, m) != 0) 1647 fatal_f("write packet: %s", strerror(errno)); 1648 1649 sshbuf_reset(m); 1650 1651 /* Read their reply */ 1652 if (mux_client_read_packet(fd, m) != 0) { 1653 sshbuf_free(m); 1654 return 0; 1655 } 1656 1657 if ((r = sshbuf_get_u32(m, &type)) != 0) 1658 fatal_fr(r, "parse type"); 1659 if (type != MUX_S_ALIVE) { 1660 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1661 fatal_fr(r, "parse error message"); 1662 fatal_f("master returned error: %s", e); 1663 } 1664 1665 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1666 fatal_fr(r, "parse remote ID"); 1667 if (rid != muxclient_request_id) 1668 fatal_f("out of sequence reply: my id %u theirs %u", 1669 muxclient_request_id, rid); 1670 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1671 fatal_fr(r, "parse PID"); 1672 sshbuf_free(m); 1673 1674 debug3_f("done pid = %u", pid); 1675 1676 muxclient_request_id++; 1677 1678 return pid; 1679 } 1680 1681 static void 1682 mux_client_request_terminate(int fd) 1683 { 1684 struct sshbuf *m; 1685 char *e; 1686 u_int type, rid; 1687 int r; 1688 1689 debug3_f("entering"); 1690 1691 if ((m = sshbuf_new()) == NULL) 1692 fatal_f("sshbuf_new"); 1693 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1694 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1695 fatal_fr(r, "request"); 1696 1697 if (mux_client_write_packet(fd, m) != 0) 1698 fatal_f("write packet: %s", strerror(errno)); 1699 1700 sshbuf_reset(m); 1701 1702 /* Read their reply */ 1703 if (mux_client_read_packet(fd, m) != 0) { 1704 /* Remote end exited already */ 1705 if (errno == EPIPE) { 1706 sshbuf_free(m); 1707 return; 1708 } 1709 fatal_f("read from master failed: %s", strerror(errno)); 1710 } 1711 1712 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1713 (r = sshbuf_get_u32(m, &rid)) != 0) 1714 fatal_fr(r, "parse"); 1715 if (rid != muxclient_request_id) 1716 fatal_f("out of sequence reply: my id %u theirs %u", 1717 muxclient_request_id, rid); 1718 switch (type) { 1719 case MUX_S_OK: 1720 break; 1721 case MUX_S_PERMISSION_DENIED: 1722 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1723 fatal_fr(r, "parse error message"); 1724 fatal("Master refused termination request: %s", e); 1725 case MUX_S_FAILURE: 1726 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1727 fatal_fr(r, "parse error message"); 1728 fatal_f("termination request failed: %s", e); 1729 default: 1730 fatal_f("unexpected response from master 0x%08x", type); 1731 } 1732 sshbuf_free(m); 1733 muxclient_request_id++; 1734 } 1735 1736 static int 1737 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1738 { 1739 struct sshbuf *m; 1740 char *e, *fwd_desc; 1741 const char *lhost, *chost; 1742 u_int type, rid; 1743 int r; 1744 1745 fwd_desc = format_forward(ftype, fwd); 1746 debug("Requesting %s %s", 1747 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1748 free(fwd_desc); 1749 1750 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1751 if (fwd->listen_path != NULL) 1752 lhost = fwd->listen_path; 1753 else if (fwd->listen_host == NULL) 1754 lhost = ""; 1755 else if (*fwd->listen_host == '\0') 1756 lhost = "*"; 1757 else 1758 lhost = fwd->listen_host; 1759 1760 if (fwd->connect_path != NULL) 1761 chost = fwd->connect_path; 1762 else if (fwd->connect_host == NULL) 1763 chost = ""; 1764 else 1765 chost = fwd->connect_host; 1766 1767 if ((m = sshbuf_new()) == NULL) 1768 fatal_f("sshbuf_new"); 1769 if ((r = sshbuf_put_u32(m, type)) != 0 || 1770 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1771 (r = sshbuf_put_u32(m, ftype)) != 0 || 1772 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1773 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1774 (r = sshbuf_put_cstring(m, chost)) != 0 || 1775 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1776 fatal_fr(r, "request"); 1777 1778 if (mux_client_write_packet(fd, m) != 0) 1779 fatal_f("write packet: %s", strerror(errno)); 1780 1781 sshbuf_reset(m); 1782 1783 /* Read their reply */ 1784 if (mux_client_read_packet(fd, m) != 0) { 1785 sshbuf_free(m); 1786 return -1; 1787 } 1788 1789 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1790 (r = sshbuf_get_u32(m, &rid)) != 0) 1791 fatal_fr(r, "parse"); 1792 if (rid != muxclient_request_id) 1793 fatal_f("out of sequence reply: my id %u theirs %u", 1794 muxclient_request_id, rid); 1795 1796 switch (type) { 1797 case MUX_S_OK: 1798 break; 1799 case MUX_S_REMOTE_PORT: 1800 if (cancel_flag) 1801 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1802 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1803 fatal_fr(r, "parse port"); 1804 verbose("Allocated port %u for remote forward to %s:%d", 1805 fwd->allocated_port, 1806 fwd->connect_host ? fwd->connect_host : "", 1807 fwd->connect_port); 1808 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1809 fprintf(stdout, "%i\n", fwd->allocated_port); 1810 break; 1811 case MUX_S_PERMISSION_DENIED: 1812 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1813 fatal_fr(r, "parse error message"); 1814 sshbuf_free(m); 1815 error("Master refused forwarding request: %s", e); 1816 return -1; 1817 case MUX_S_FAILURE: 1818 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1819 fatal_fr(r, "parse error message"); 1820 sshbuf_free(m); 1821 error_f("forwarding request failed: %s", e); 1822 return -1; 1823 default: 1824 fatal_f("unexpected response from master 0x%08x", type); 1825 } 1826 sshbuf_free(m); 1827 1828 muxclient_request_id++; 1829 return 0; 1830 } 1831 1832 static int 1833 mux_client_forwards(int fd, int cancel_flag) 1834 { 1835 int i, ret = 0; 1836 1837 debug3_f("%s forwardings: %d local, %d remote", 1838 cancel_flag ? "cancel" : "request", 1839 options.num_local_forwards, options.num_remote_forwards); 1840 1841 /* XXX ExitOnForwardingFailure */ 1842 for (i = 0; i < options.num_local_forwards; i++) { 1843 if (mux_client_forward(fd, cancel_flag, 1844 options.local_forwards[i].connect_port == 0 ? 1845 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1846 options.local_forwards + i) != 0) 1847 ret = -1; 1848 } 1849 for (i = 0; i < options.num_remote_forwards; i++) { 1850 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1851 options.remote_forwards + i) != 0) 1852 ret = -1; 1853 } 1854 return ret; 1855 } 1856 1857 static int 1858 mux_client_request_session(int fd) 1859 { 1860 struct sshbuf *m; 1861 char *e; 1862 const char *term = NULL; 1863 u_int i, echar, rid, sid, esid, exitval, type, exitval_seen; 1864 extern char **environ; 1865 int r, rawmode; 1866 1867 debug3_f("entering"); 1868 1869 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1870 error_f("master alive request failed"); 1871 return -1; 1872 } 1873 1874 ssh_signal(SIGPIPE, SIG_IGN); 1875 1876 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 1877 fatal_f("stdfd_devnull failed"); 1878 1879 if ((term = lookup_env_in_list("TERM", options.setenv, 1880 options.num_setenv)) == NULL || *term == '\0') 1881 term = getenv("TERM"); 1882 1883 echar = 0xffffffff; 1884 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1885 echar = (u_int)options.escape_char; 1886 1887 if ((m = sshbuf_new()) == NULL) 1888 fatal_f("sshbuf_new"); 1889 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1890 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1891 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1892 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1893 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1894 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1895 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 || 1896 (r = sshbuf_put_u32(m, echar)) != 0 || 1897 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 || 1898 (r = sshbuf_put_stringb(m, command)) != 0) 1899 fatal_fr(r, "request"); 1900 1901 /* Pass environment */ 1902 if (options.num_send_env > 0 && environ != NULL) { 1903 for (i = 0; environ[i] != NULL; i++) { 1904 if (!env_permitted(environ[i])) 1905 continue; 1906 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1907 fatal_fr(r, "request sendenv"); 1908 } 1909 } 1910 for (i = 0; i < options.num_setenv; i++) { 1911 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1912 fatal_fr(r, "request setenv"); 1913 } 1914 1915 if (mux_client_write_packet(fd, m) != 0) 1916 fatal_f("write packet: %s", strerror(errno)); 1917 1918 /* Send the stdio file descriptors */ 1919 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1920 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1921 mm_send_fd(fd, STDERR_FILENO) == -1) 1922 fatal_f("send fds failed"); 1923 1924 debug3_f("session request sent"); 1925 1926 /* Read their reply */ 1927 sshbuf_reset(m); 1928 if (mux_client_read_packet(fd, m) != 0) { 1929 error_f("read from master failed: %s", strerror(errno)); 1930 sshbuf_free(m); 1931 return -1; 1932 } 1933 1934 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1935 (r = sshbuf_get_u32(m, &rid)) != 0) 1936 fatal_fr(r, "parse"); 1937 if (rid != muxclient_request_id) 1938 fatal_f("out of sequence reply: my id %u theirs %u", 1939 muxclient_request_id, rid); 1940 1941 switch (type) { 1942 case MUX_S_SESSION_OPENED: 1943 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1944 fatal_fr(r, "parse session ID"); 1945 debug_f("master session id: %u", sid); 1946 break; 1947 case MUX_S_PERMISSION_DENIED: 1948 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1949 fatal_fr(r, "parse error message"); 1950 error("Master refused session request: %s", e); 1951 sshbuf_free(m); 1952 return -1; 1953 case MUX_S_FAILURE: 1954 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1955 fatal_fr(r, "parse error message"); 1956 error_f("session request failed: %s", e); 1957 sshbuf_free(m); 1958 return -1; 1959 default: 1960 sshbuf_free(m); 1961 error_f("unexpected response from master 0x%08x", type); 1962 return -1; 1963 } 1964 muxclient_request_id++; 1965 1966 if (pledge("stdio proc tty", NULL) == -1) 1967 fatal_f("pledge(): %s", strerror(errno)); 1968 1969 ssh_signal(SIGHUP, control_client_sighandler); 1970 ssh_signal(SIGINT, control_client_sighandler); 1971 ssh_signal(SIGTERM, control_client_sighandler); 1972 ssh_signal(SIGWINCH, control_client_sigrelay); 1973 1974 rawmode = tty_flag; 1975 if (tty_flag) 1976 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1977 1978 /* 1979 * Stick around until the controlee closes the client_fd. 1980 * Before it does, it is expected to write an exit message. 1981 * This process must read the value and wait for the closure of 1982 * the client_fd; if this one closes early, the multiplex master will 1983 * terminate early too (possibly losing data). 1984 */ 1985 for (exitval = 255, exitval_seen = 0;;) { 1986 sshbuf_reset(m); 1987 if (mux_client_read_packet(fd, m) != 0) 1988 break; 1989 if ((r = sshbuf_get_u32(m, &type)) != 0) 1990 fatal_fr(r, "parse type"); 1991 switch (type) { 1992 case MUX_S_TTY_ALLOC_FAIL: 1993 if ((r = sshbuf_get_u32(m, &esid)) != 0) 1994 fatal_fr(r, "parse session ID"); 1995 if (esid != sid) 1996 fatal_f("tty alloc fail on unknown session: " 1997 "my id %u theirs %u", sid, esid); 1998 leave_raw_mode(options.request_tty == 1999 REQUEST_TTY_FORCE); 2000 rawmode = 0; 2001 continue; 2002 case MUX_S_EXIT_MESSAGE: 2003 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2004 fatal_fr(r, "parse session ID"); 2005 if (esid != sid) 2006 fatal_f("exit on unknown session: " 2007 "my id %u theirs %u", sid, esid); 2008 if (exitval_seen) 2009 fatal_f("exitval sent twice"); 2010 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2011 fatal_fr(r, "parse exitval"); 2012 exitval_seen = 1; 2013 continue; 2014 default: 2015 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2016 fatal_fr(r, "parse error message"); 2017 fatal_f("master returned error: %s", e); 2018 } 2019 } 2020 2021 close(fd); 2022 if (rawmode) 2023 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2024 2025 if (muxclient_terminate) { 2026 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2027 exitval = 255; 2028 } else if (!exitval_seen) { 2029 debug2("Control master terminated unexpectedly"); 2030 exitval = 255; 2031 } else 2032 debug2("Received exit status from master %d", exitval); 2033 2034 if (tty_flag && options.log_level >= SYSLOG_LEVEL_INFO) 2035 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2036 2037 exit(exitval); 2038 } 2039 2040 static int 2041 mux_client_proxy(int fd) 2042 { 2043 struct sshbuf *m; 2044 char *e; 2045 u_int type, rid; 2046 int r; 2047 2048 if ((m = sshbuf_new()) == NULL) 2049 fatal_f("sshbuf_new"); 2050 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2051 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2052 fatal_fr(r, "request"); 2053 if (mux_client_write_packet(fd, m) != 0) 2054 fatal_f("write packet: %s", strerror(errno)); 2055 2056 sshbuf_reset(m); 2057 2058 /* Read their reply */ 2059 if (mux_client_read_packet(fd, m) != 0) { 2060 sshbuf_free(m); 2061 return 0; 2062 } 2063 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2064 (r = sshbuf_get_u32(m, &rid)) != 0) 2065 fatal_fr(r, "parse"); 2066 if (rid != muxclient_request_id) 2067 fatal_f("out of sequence reply: my id %u theirs %u", 2068 muxclient_request_id, rid); 2069 if (type != MUX_S_PROXY) { 2070 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2071 fatal_fr(r, "parse error message"); 2072 fatal_f("master returned error: %s", e); 2073 } 2074 sshbuf_free(m); 2075 2076 debug3_f("done"); 2077 muxclient_request_id++; 2078 return 0; 2079 } 2080 2081 static int 2082 mux_client_request_stdio_fwd(int fd) 2083 { 2084 struct sshbuf *m; 2085 char *e; 2086 u_int type, rid, sid; 2087 int r; 2088 2089 debug3_f("entering"); 2090 2091 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2092 error_f("master alive request failed"); 2093 return -1; 2094 } 2095 2096 ssh_signal(SIGPIPE, SIG_IGN); 2097 2098 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 2099 fatal_f("stdfd_devnull failed"); 2100 2101 if ((m = sshbuf_new()) == NULL) 2102 fatal_f("sshbuf_new"); 2103 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2104 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2105 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2106 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2107 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2108 fatal_fr(r, "request"); 2109 2110 if (mux_client_write_packet(fd, m) != 0) 2111 fatal_f("write packet: %s", strerror(errno)); 2112 2113 /* Send the stdio file descriptors */ 2114 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2115 mm_send_fd(fd, STDOUT_FILENO) == -1) 2116 fatal_f("send fds failed"); 2117 2118 if (pledge("stdio proc tty", NULL) == -1) 2119 fatal_f("pledge(): %s", strerror(errno)); 2120 2121 debug3_f("stdio forward request sent"); 2122 2123 /* Read their reply */ 2124 sshbuf_reset(m); 2125 2126 if (mux_client_read_packet(fd, m) != 0) { 2127 error_f("read from master failed: %s", strerror(errno)); 2128 sshbuf_free(m); 2129 return -1; 2130 } 2131 2132 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2133 (r = sshbuf_get_u32(m, &rid)) != 0) 2134 fatal_fr(r, "parse"); 2135 if (rid != muxclient_request_id) 2136 fatal_f("out of sequence reply: my id %u theirs %u", 2137 muxclient_request_id, rid); 2138 switch (type) { 2139 case MUX_S_SESSION_OPENED: 2140 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2141 fatal_fr(r, "parse session ID"); 2142 debug_f("master session id: %u", sid); 2143 break; 2144 case MUX_S_PERMISSION_DENIED: 2145 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2146 fatal_fr(r, "parse error message"); 2147 sshbuf_free(m); 2148 fatal("Master refused stdio forwarding request: %s", e); 2149 case MUX_S_FAILURE: 2150 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2151 fatal_fr(r, "parse error message"); 2152 sshbuf_free(m); 2153 fatal("Stdio forwarding request failed: %s", e); 2154 default: 2155 sshbuf_free(m); 2156 error_f("unexpected response from master 0x%08x", type); 2157 return -1; 2158 } 2159 muxclient_request_id++; 2160 2161 ssh_signal(SIGHUP, control_client_sighandler); 2162 ssh_signal(SIGINT, control_client_sighandler); 2163 ssh_signal(SIGTERM, control_client_sighandler); 2164 ssh_signal(SIGWINCH, control_client_sigrelay); 2165 2166 /* 2167 * Stick around until the controlee closes the client_fd. 2168 */ 2169 sshbuf_reset(m); 2170 if (mux_client_read_packet(fd, m) != 0) { 2171 if (errno == EPIPE || 2172 (errno == EINTR && muxclient_terminate != 0)) 2173 return 0; 2174 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2175 } 2176 fatal_f("master returned unexpected message %u", type); 2177 } 2178 2179 static void 2180 mux_client_request_stop_listening(int fd) 2181 { 2182 struct sshbuf *m; 2183 char *e; 2184 u_int type, rid; 2185 int r; 2186 2187 debug3_f("entering"); 2188 2189 if ((m = sshbuf_new()) == NULL) 2190 fatal_f("sshbuf_new"); 2191 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2192 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2193 fatal_fr(r, "request"); 2194 2195 if (mux_client_write_packet(fd, m) != 0) 2196 fatal_f("write packet: %s", strerror(errno)); 2197 2198 sshbuf_reset(m); 2199 2200 /* Read their reply */ 2201 if (mux_client_read_packet(fd, m) != 0) 2202 fatal_f("read from master failed: %s", strerror(errno)); 2203 2204 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2205 (r = sshbuf_get_u32(m, &rid)) != 0) 2206 fatal_fr(r, "parse"); 2207 if (rid != muxclient_request_id) 2208 fatal_f("out of sequence reply: my id %u theirs %u", 2209 muxclient_request_id, rid); 2210 2211 switch (type) { 2212 case MUX_S_OK: 2213 break; 2214 case MUX_S_PERMISSION_DENIED: 2215 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2216 fatal_fr(r, "parse error message"); 2217 fatal("Master refused stop listening request: %s", e); 2218 case MUX_S_FAILURE: 2219 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2220 fatal_fr(r, "parse error message"); 2221 fatal_f("stop listening request failed: %s", e); 2222 default: 2223 fatal_f("unexpected response from master 0x%08x", type); 2224 } 2225 sshbuf_free(m); 2226 muxclient_request_id++; 2227 } 2228 2229 /* Multiplex client main loop. */ 2230 int 2231 muxclient(const char *path) 2232 { 2233 struct sockaddr_un addr; 2234 int sock; 2235 u_int pid; 2236 2237 if (muxclient_command == 0) { 2238 if (options.stdio_forward_host != NULL) 2239 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2240 else 2241 muxclient_command = SSHMUX_COMMAND_OPEN; 2242 } 2243 2244 switch (options.control_master) { 2245 case SSHCTL_MASTER_AUTO: 2246 case SSHCTL_MASTER_AUTO_ASK: 2247 debug("auto-mux: Trying existing master"); 2248 /* FALLTHROUGH */ 2249 case SSHCTL_MASTER_NO: 2250 break; 2251 default: 2252 return -1; 2253 } 2254 2255 memset(&addr, '\0', sizeof(addr)); 2256 addr.sun_family = AF_UNIX; 2257 2258 if (strlcpy(addr.sun_path, path, 2259 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2260 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2261 (unsigned int)sizeof(addr.sun_path)); 2262 2263 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2264 fatal_f("socket(): %s", strerror(errno)); 2265 2266 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2267 switch (muxclient_command) { 2268 case SSHMUX_COMMAND_OPEN: 2269 case SSHMUX_COMMAND_STDIO_FWD: 2270 break; 2271 default: 2272 fatal("Control socket connect(%.100s): %s", path, 2273 strerror(errno)); 2274 } 2275 if (errno == ECONNREFUSED && 2276 options.control_master != SSHCTL_MASTER_NO) { 2277 debug("Stale control socket %.100s, unlinking", path); 2278 unlink(path); 2279 } else if (errno == ENOENT) { 2280 debug("Control socket \"%.100s\" does not exist", path); 2281 } else { 2282 error("Control socket connect(%.100s): %s", path, 2283 strerror(errno)); 2284 } 2285 close(sock); 2286 return -1; 2287 } 2288 set_nonblock(sock); 2289 2290 if (mux_client_hello_exchange(sock) != 0) { 2291 error_f("master hello exchange failed"); 2292 close(sock); 2293 return -1; 2294 } 2295 2296 switch (muxclient_command) { 2297 case SSHMUX_COMMAND_ALIVE_CHECK: 2298 if ((pid = mux_client_request_alive(sock)) == 0) 2299 fatal_f("master alive check failed"); 2300 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2301 exit(0); 2302 case SSHMUX_COMMAND_TERMINATE: 2303 mux_client_request_terminate(sock); 2304 if (options.log_level != SYSLOG_LEVEL_QUIET) 2305 fprintf(stderr, "Exit request sent.\r\n"); 2306 exit(0); 2307 case SSHMUX_COMMAND_FORWARD: 2308 if (mux_client_forwards(sock, 0) != 0) 2309 fatal_f("master forward request failed"); 2310 exit(0); 2311 case SSHMUX_COMMAND_OPEN: 2312 if (mux_client_forwards(sock, 0) != 0) { 2313 error_f("master forward request failed"); 2314 return -1; 2315 } 2316 mux_client_request_session(sock); 2317 return -1; 2318 case SSHMUX_COMMAND_STDIO_FWD: 2319 mux_client_request_stdio_fwd(sock); 2320 exit(0); 2321 case SSHMUX_COMMAND_STOP: 2322 mux_client_request_stop_listening(sock); 2323 if (options.log_level != SYSLOG_LEVEL_QUIET) 2324 fprintf(stderr, "Stop listening request sent.\r\n"); 2325 exit(0); 2326 case SSHMUX_COMMAND_CANCEL_FWD: 2327 if (mux_client_forwards(sock, 1) != 0) 2328 error_f("master cancel forward request failed"); 2329 exit(0); 2330 case SSHMUX_COMMAND_PROXY: 2331 mux_client_proxy(sock); 2332 return (sock); 2333 default: 2334 fatal("unrecognised muxclient_command %d", muxclient_command); 2335 } 2336 } 2337