1 /* $OpenBSD: mux.c,v 1.101 2023/11/23 03:37:05 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 "includes.h" 21 22 #include <sys/types.h> 23 #include <sys/stat.h> 24 #include <sys/socket.h> 25 #include <sys/un.h> 26 27 #include <errno.h> 28 #include <fcntl.h> 29 #include <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 #ifdef HAVE_PATHS_H 38 #include <paths.h> 39 #endif 40 41 #ifdef HAVE_POLL_H 42 #include <poll.h> 43 #else 44 # ifdef HAVE_SYS_POLL_H 45 # include <sys/poll.h> 46 # endif 47 #endif 48 49 #ifdef HAVE_UTIL_H 50 # include <util.h> 51 #endif 52 53 #include "openbsd-compat/sys-queue.h" 54 #include "xmalloc.h" 55 #include "log.h" 56 #include "ssh.h" 57 #include "ssh2.h" 58 #include "pathnames.h" 59 #include "misc.h" 60 #include "match.h" 61 #include "sshbuf.h" 62 #include "channels.h" 63 #include "msg.h" 64 #include "packet.h" 65 #include "monitor_fdpass.h" 66 #include "sshpty.h" 67 #include "sshkey.h" 68 #include "readconf.h" 69 #include "clientloop.h" 70 #include "ssherr.h" 71 #include "misc.h" 72 73 /* from ssh.c */ 74 extern int tty_flag; 75 extern Options options; 76 extern char *host; 77 extern struct sshbuf *command; 78 extern volatile sig_atomic_t quit_pending; 79 80 /* Context for session open confirmation callback */ 81 struct mux_session_confirm_ctx { 82 u_int want_tty; 83 u_int want_subsys; 84 u_int want_x_fwd; 85 u_int want_agent_fwd; 86 struct sshbuf *cmd; 87 char *term; 88 struct termios tio; 89 char **env; 90 u_int rid; 91 }; 92 93 /* Context for stdio fwd open confirmation callback */ 94 struct mux_stdio_confirm_ctx { 95 u_int rid; 96 }; 97 98 /* Context for global channel callback */ 99 struct mux_channel_confirm_ctx { 100 u_int cid; /* channel id */ 101 u_int rid; /* request id */ 102 int fid; /* forward id */ 103 }; 104 105 /* fd to control socket */ 106 int muxserver_sock = -1; 107 108 /* client request id */ 109 u_int muxclient_request_id = 0; 110 111 /* Multiplexing control command */ 112 u_int muxclient_command = 0; 113 114 /* Set when signalled. */ 115 static volatile sig_atomic_t muxclient_terminate = 0; 116 117 /* PID of multiplex server */ 118 static u_int muxserver_pid = 0; 119 120 static Channel *mux_listener_channel = NULL; 121 122 struct mux_master_state { 123 int hello_rcvd; 124 }; 125 126 /* mux protocol messages */ 127 #define MUX_MSG_HELLO 0x00000001 128 #define MUX_C_NEW_SESSION 0x10000002 129 #define MUX_C_ALIVE_CHECK 0x10000004 130 #define MUX_C_TERMINATE 0x10000005 131 #define MUX_C_OPEN_FWD 0x10000006 132 #define MUX_C_CLOSE_FWD 0x10000007 133 #define MUX_C_NEW_STDIO_FWD 0x10000008 134 #define MUX_C_STOP_LISTENING 0x10000009 135 #define MUX_C_PROXY 0x1000000f 136 #define MUX_S_OK 0x80000001 137 #define MUX_S_PERMISSION_DENIED 0x80000002 138 #define MUX_S_FAILURE 0x80000003 139 #define MUX_S_EXIT_MESSAGE 0x80000004 140 #define MUX_S_ALIVE 0x80000005 141 #define MUX_S_SESSION_OPENED 0x80000006 142 #define MUX_S_REMOTE_PORT 0x80000007 143 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 144 #define MUX_S_PROXY 0x8000000f 145 146 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 147 #define MUX_FWD_LOCAL 1 148 #define MUX_FWD_REMOTE 2 149 #define MUX_FWD_DYNAMIC 3 150 151 static void mux_session_confirm(struct ssh *, int, int, void *); 152 static void mux_stdio_confirm(struct ssh *, int, int, void *); 153 154 static int mux_master_process_hello(struct ssh *, u_int, 155 Channel *, struct sshbuf *, struct sshbuf *); 156 static int mux_master_process_new_session(struct ssh *, u_int, 157 Channel *, struct sshbuf *, struct sshbuf *); 158 static int mux_master_process_alive_check(struct ssh *, u_int, 159 Channel *, struct sshbuf *, struct sshbuf *); 160 static int mux_master_process_terminate(struct ssh *, u_int, 161 Channel *, struct sshbuf *, struct sshbuf *); 162 static int mux_master_process_open_fwd(struct ssh *, u_int, 163 Channel *, struct sshbuf *, struct sshbuf *); 164 static int mux_master_process_close_fwd(struct ssh *, u_int, 165 Channel *, struct sshbuf *, struct sshbuf *); 166 static int mux_master_process_stdio_fwd(struct ssh *, u_int, 167 Channel *, struct sshbuf *, struct sshbuf *); 168 static int mux_master_process_stop_listening(struct ssh *, u_int, 169 Channel *, struct sshbuf *, struct sshbuf *); 170 static int mux_master_process_proxy(struct ssh *, u_int, 171 Channel *, struct sshbuf *, struct sshbuf *); 172 173 static const struct { 174 u_int type; 175 int (*handler)(struct ssh *, u_int, Channel *, 176 struct sshbuf *, struct sshbuf *); 177 } mux_master_handlers[] = { 178 { MUX_MSG_HELLO, mux_master_process_hello }, 179 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 180 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 181 { MUX_C_TERMINATE, mux_master_process_terminate }, 182 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 183 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 184 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 185 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 186 { MUX_C_PROXY, mux_master_process_proxy }, 187 { 0, NULL } 188 }; 189 190 /* Cleanup callback fired on closure of mux client _session_ channel */ 191 static void 192 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 193 { 194 Channel *cc, *c = channel_by_id(ssh, cid); 195 196 debug3_f("entering for channel %d", cid); 197 if (c == NULL) 198 fatal_f("channel_by_id(%i) == NULL", cid); 199 if (c->ctl_chan != -1) { 200 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 201 fatal_f("channel %d missing control channel %d", 202 c->self, c->ctl_chan); 203 c->ctl_chan = -1; 204 cc->remote_id = 0; 205 cc->have_remote_id = 0; 206 chan_rcvd_oclose(ssh, cc); 207 } 208 channel_cancel_cleanup(ssh, c->self); 209 } 210 211 /* Cleanup callback fired on closure of mux client _control_ channel */ 212 static void 213 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 214 { 215 Channel *sc, *c = channel_by_id(ssh, cid); 216 217 debug3_f("entering for channel %d", cid); 218 if (c == NULL) 219 fatal_f("channel_by_id(%i) == NULL", cid); 220 if (c->have_remote_id) { 221 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 222 fatal_f("channel %d missing session channel %u", 223 c->self, c->remote_id); 224 c->remote_id = 0; 225 c->have_remote_id = 0; 226 sc->ctl_chan = -1; 227 if (sc->type != SSH_CHANNEL_OPEN && 228 sc->type != SSH_CHANNEL_OPENING) { 229 debug2_f("channel %d: not open", sc->self); 230 chan_mark_dead(ssh, sc); 231 } else { 232 if (sc->istate == CHAN_INPUT_OPEN) 233 chan_read_failed(ssh, sc); 234 if (sc->ostate == CHAN_OUTPUT_OPEN) 235 chan_write_failed(ssh, sc); 236 } 237 } 238 channel_cancel_cleanup(ssh, c->self); 239 } 240 241 /* Check mux client environment variables before passing them to mux master. */ 242 static int 243 env_permitted(const char *env) 244 { 245 u_int i; 246 int ret; 247 char name[1024], *cp; 248 249 if ((cp = strchr(env, '=')) == NULL || cp == env) 250 return 0; 251 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 252 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 253 error_f("name '%.100s...' too long", env); 254 return 0; 255 } 256 257 for (i = 0; i < options.num_send_env; i++) 258 if (match_pattern(name, options.send_env[i])) 259 return 1; 260 261 return 0; 262 } 263 264 /* Mux master protocol message handlers */ 265 266 static int 267 mux_master_process_hello(struct ssh *ssh, u_int rid, 268 Channel *c, struct sshbuf *m, struct sshbuf *reply) 269 { 270 u_int ver; 271 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 272 int r; 273 274 if (state == NULL) 275 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 276 if (state->hello_rcvd) { 277 error_f("HELLO received twice"); 278 return -1; 279 } 280 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 281 error_fr(r, "parse"); 282 return -1; 283 } 284 if (ver != SSHMUX_VER) { 285 error_f("unsupported multiplexing protocol version %u " 286 "(expected %u)", ver, SSHMUX_VER); 287 return -1; 288 } 289 debug2_f("channel %d client version %u", c->self, ver); 290 291 /* No extensions are presently defined */ 292 while (sshbuf_len(m) > 0) { 293 char *name = NULL; 294 size_t value_len = 0; 295 296 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 297 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 298 error_fr(r, "parse extension"); 299 return -1; 300 } 301 debug2_f("Unrecognised extension \"%s\" length %zu", 302 name, value_len); 303 free(name); 304 } 305 state->hello_rcvd = 1; 306 return 0; 307 } 308 309 /* Enqueue a "ok" response to the reply buffer */ 310 static void 311 reply_ok(struct sshbuf *reply, u_int rid) 312 { 313 int r; 314 315 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 316 (r = sshbuf_put_u32(reply, rid)) != 0) 317 fatal_fr(r, "reply"); 318 } 319 320 /* Enqueue an error response to the reply buffer */ 321 static void 322 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 323 { 324 int r; 325 326 if ((r = sshbuf_put_u32(reply, type)) != 0 || 327 (r = sshbuf_put_u32(reply, rid)) != 0 || 328 (r = sshbuf_put_cstring(reply, msg)) != 0) 329 fatal_fr(r, "reply"); 330 } 331 332 static int 333 mux_master_process_new_session(struct ssh *ssh, u_int rid, 334 Channel *c, struct sshbuf *m, struct sshbuf *reply) 335 { 336 Channel *nc; 337 struct mux_session_confirm_ctx *cctx; 338 char *cmd, *cp; 339 u_int i, j, env_len, escape_char, window, packetmax; 340 int r, new_fd[3]; 341 342 /* Reply for SSHMUX_COMMAND_OPEN */ 343 cctx = xcalloc(1, sizeof(*cctx)); 344 cctx->term = NULL; 345 cctx->rid = rid; 346 cmd = NULL; 347 cctx->env = NULL; 348 env_len = 0; 349 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 350 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 351 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 352 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 353 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 354 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 355 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 356 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 357 malf: 358 free(cmd); 359 for (j = 0; j < env_len; j++) 360 free(cctx->env[j]); 361 free(cctx->env); 362 free(cctx->term); 363 free(cctx); 364 error_f("malformed message"); 365 return -1; 366 } 367 368 #define MUX_MAX_ENV_VARS 4096 369 while (sshbuf_len(m) > 0) { 370 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 371 goto malf; 372 if (!env_permitted(cp)) { 373 free(cp); 374 continue; 375 } 376 cctx->env = xreallocarray(cctx->env, env_len + 2, 377 sizeof(*cctx->env)); 378 cctx->env[env_len++] = cp; 379 cctx->env[env_len] = NULL; 380 if (env_len > MUX_MAX_ENV_VARS) { 381 error_f(">%d environment variables received, " 382 "ignoring additional", MUX_MAX_ENV_VARS); 383 break; 384 } 385 } 386 387 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 388 "term \"%s\", cmd \"%s\", env %u", c->self, 389 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 390 cctx->want_subsys, cctx->term, cmd, env_len); 391 392 if ((cctx->cmd = sshbuf_new()) == NULL) 393 fatal_f("sshbuf_new"); 394 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 395 fatal_fr(r, "sshbuf_put"); 396 free(cmd); 397 cmd = NULL; 398 399 /* Gather fds from client */ 400 for(i = 0; i < 3; i++) { 401 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 402 error_f("failed to receive fd %d from client", i); 403 for (j = 0; j < i; j++) 404 close(new_fd[j]); 405 for (j = 0; j < env_len; j++) 406 free(cctx->env[j]); 407 free(cctx->env); 408 free(cctx->term); 409 sshbuf_free(cctx->cmd); 410 free(cctx); 411 reply_error(reply, MUX_S_FAILURE, rid, 412 "did not receive file descriptors"); 413 return -1; 414 } 415 } 416 417 debug3_f("got fds stdin %d, stdout %d, stderr %d", 418 new_fd[0], new_fd[1], new_fd[2]); 419 420 /* XXX support multiple child sessions in future */ 421 if (c->have_remote_id) { 422 debug2_f("session already open"); 423 reply_error(reply, MUX_S_FAILURE, rid, 424 "Multiple sessions not supported"); 425 cleanup: 426 close(new_fd[0]); 427 close(new_fd[1]); 428 close(new_fd[2]); 429 free(cctx->term); 430 if (env_len != 0) { 431 for (i = 0; i < env_len; i++) 432 free(cctx->env[i]); 433 free(cctx->env); 434 } 435 sshbuf_free(cctx->cmd); 436 free(cctx); 437 return 0; 438 } 439 440 if (options.control_master == SSHCTL_MASTER_ASK || 441 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 442 if (!ask_permission("Allow shared connection to %s? ", host)) { 443 debug2_f("session refused by user"); 444 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 445 "Permission denied"); 446 goto cleanup; 447 } 448 } 449 450 /* Try to pick up ttymodes from client before it goes raw */ 451 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 452 error_f("tcgetattr: %s", strerror(errno)); 453 454 window = CHAN_SES_WINDOW_DEFAULT; 455 packetmax = CHAN_SES_PACKET_DEFAULT; 456 if (cctx->want_tty) { 457 window >>= 1; 458 packetmax >>= 1; 459 } 460 461 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 462 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 463 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO); 464 465 nc->ctl_chan = c->self; /* link session -> control channel */ 466 c->remote_id = nc->self; /* link control -> session channel */ 467 c->have_remote_id = 1; 468 469 if (cctx->want_tty && escape_char != 0xffffffff) { 470 channel_register_filter(ssh, nc->self, 471 client_simple_escape_filter, NULL, 472 client_filter_cleanup, 473 client_new_escape_filter_ctx((int)escape_char)); 474 } 475 476 debug2_f("channel_new: %d linked to control channel %d", 477 nc->self, nc->ctl_chan); 478 479 channel_send_open(ssh, nc->self); 480 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 481 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 482 channel_register_cleanup(ssh, nc->self, 483 mux_master_session_cleanup_cb, 1); 484 485 /* reply is deferred, sent by mux_session_confirm */ 486 return 0; 487 } 488 489 static int 490 mux_master_process_alive_check(struct ssh *ssh, u_int rid, 491 Channel *c, struct sshbuf *m, struct sshbuf *reply) 492 { 493 int r; 494 495 debug2_f("channel %d: alive check", c->self); 496 497 /* prepare reply */ 498 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 499 (r = sshbuf_put_u32(reply, rid)) != 0 || 500 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 501 fatal_fr(r, "reply"); 502 503 return 0; 504 } 505 506 static int 507 mux_master_process_terminate(struct ssh *ssh, u_int rid, 508 Channel *c, struct sshbuf *m, struct sshbuf *reply) 509 { 510 debug2_f("channel %d: terminate request", c->self); 511 512 if (options.control_master == SSHCTL_MASTER_ASK || 513 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 514 if (!ask_permission("Terminate shared connection to %s? ", 515 host)) { 516 debug2_f("termination refused by user"); 517 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 518 "Permission denied"); 519 return 0; 520 } 521 } 522 523 quit_pending = 1; 524 reply_ok(reply, rid); 525 /* XXX exit happens too soon - message never makes it to client */ 526 return 0; 527 } 528 529 static char * 530 format_forward(u_int ftype, struct Forward *fwd) 531 { 532 char *ret; 533 534 switch (ftype) { 535 case MUX_FWD_LOCAL: 536 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 537 (fwd->listen_path != NULL) ? fwd->listen_path : 538 (fwd->listen_host == NULL) ? 539 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 540 fwd->listen_host, fwd->listen_port, 541 (fwd->connect_path != NULL) ? fwd->connect_path : 542 fwd->connect_host, fwd->connect_port); 543 break; 544 case MUX_FWD_DYNAMIC: 545 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 546 (fwd->listen_host == NULL) ? 547 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 548 fwd->listen_host, fwd->listen_port); 549 break; 550 case MUX_FWD_REMOTE: 551 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 552 (fwd->listen_path != NULL) ? fwd->listen_path : 553 (fwd->listen_host == NULL) ? 554 "LOCALHOST" : fwd->listen_host, 555 fwd->listen_port, 556 (fwd->connect_path != NULL) ? fwd->connect_path : 557 fwd->connect_host, fwd->connect_port); 558 break; 559 default: 560 fatal_f("unknown forward type %u", ftype); 561 } 562 return ret; 563 } 564 565 static int 566 compare_host(const char *a, const char *b) 567 { 568 if (a == NULL && b == NULL) 569 return 1; 570 if (a == NULL || b == NULL) 571 return 0; 572 return strcmp(a, b) == 0; 573 } 574 575 static int 576 compare_forward(struct Forward *a, struct Forward *b) 577 { 578 if (!compare_host(a->listen_host, b->listen_host)) 579 return 0; 580 if (!compare_host(a->listen_path, b->listen_path)) 581 return 0; 582 if (a->listen_port != b->listen_port) 583 return 0; 584 if (!compare_host(a->connect_host, b->connect_host)) 585 return 0; 586 if (!compare_host(a->connect_path, b->connect_path)) 587 return 0; 588 if (a->connect_port != b->connect_port) 589 return 0; 590 591 return 1; 592 } 593 594 static void 595 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 596 { 597 struct mux_channel_confirm_ctx *fctx = ctxt; 598 char *failmsg = NULL; 599 struct Forward *rfwd; 600 Channel *c; 601 struct sshbuf *out; 602 u_int port; 603 int r; 604 605 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 606 /* no channel for reply */ 607 error_f("unknown channel"); 608 return; 609 } 610 if ((out = sshbuf_new()) == NULL) 611 fatal_f("sshbuf_new"); 612 if (fctx->fid >= options.num_remote_forwards || 613 (options.remote_forwards[fctx->fid].connect_path == NULL && 614 options.remote_forwards[fctx->fid].connect_host == NULL)) { 615 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 616 goto fail; 617 } 618 rfwd = &options.remote_forwards[fctx->fid]; 619 debug_f("%s for: listen %d, connect %s:%d", 620 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 621 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 622 rfwd->connect_host, rfwd->connect_port); 623 if (type == SSH2_MSG_REQUEST_SUCCESS) { 624 if (rfwd->listen_port == 0) { 625 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 626 fatal_fr(r, "parse port"); 627 if (port > 65535) { 628 fatal("Invalid allocated port %u for " 629 "mux remote forward to %s:%d", port, 630 rfwd->connect_host, rfwd->connect_port); 631 } 632 rfwd->allocated_port = (int)port; 633 debug("Allocated port %u for mux remote forward" 634 " to %s:%d", rfwd->allocated_port, 635 rfwd->connect_host, rfwd->connect_port); 636 if ((r = sshbuf_put_u32(out, 637 MUX_S_REMOTE_PORT)) != 0 || 638 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 639 (r = sshbuf_put_u32(out, 640 rfwd->allocated_port)) != 0) 641 fatal_fr(r, "reply"); 642 channel_update_permission(ssh, rfwd->handle, 643 rfwd->allocated_port); 644 } else { 645 reply_ok(out, fctx->rid); 646 } 647 goto out; 648 } else { 649 if (rfwd->listen_port == 0) 650 channel_update_permission(ssh, rfwd->handle, -1); 651 if (rfwd->listen_path != NULL) 652 xasprintf(&failmsg, "remote port forwarding failed for " 653 "listen path %s", rfwd->listen_path); 654 else 655 xasprintf(&failmsg, "remote port forwarding failed for " 656 "listen port %d", rfwd->listen_port); 657 658 debug2_f("clearing registered forwarding for listen %d, " 659 "connect %s:%d", rfwd->listen_port, 660 rfwd->connect_path ? rfwd->connect_path : 661 rfwd->connect_host, rfwd->connect_port); 662 663 free(rfwd->listen_host); 664 free(rfwd->listen_path); 665 free(rfwd->connect_host); 666 free(rfwd->connect_path); 667 memset(rfwd, 0, sizeof(*rfwd)); 668 } 669 fail: 670 error_f("%s", failmsg); 671 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 672 free(failmsg); 673 out: 674 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 675 fatal_fr(r, "enqueue"); 676 sshbuf_free(out); 677 if (c->mux_pause <= 0) 678 fatal_f("mux_pause %d", c->mux_pause); 679 c->mux_pause = 0; /* start processing messages again */ 680 } 681 682 static int 683 mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 684 Channel *c, struct sshbuf *m, struct sshbuf *reply) 685 { 686 struct Forward fwd; 687 char *fwd_desc = NULL; 688 char *listen_addr, *connect_addr; 689 u_int ftype; 690 u_int lport, cport; 691 int r, i, ret = 0, freefwd = 1; 692 693 memset(&fwd, 0, sizeof(fwd)); 694 695 /* XXX - lport/cport check redundant */ 696 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 697 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 698 (r = sshbuf_get_u32(m, &lport)) != 0 || 699 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 700 (r = sshbuf_get_u32(m, &cport)) != 0 || 701 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 702 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 703 error_f("malformed message"); 704 ret = -1; 705 goto out; 706 } 707 if (*listen_addr == '\0') { 708 free(listen_addr); 709 listen_addr = NULL; 710 } 711 if (*connect_addr == '\0') { 712 free(connect_addr); 713 connect_addr = NULL; 714 } 715 716 memset(&fwd, 0, sizeof(fwd)); 717 fwd.listen_port = lport; 718 if (fwd.listen_port == PORT_STREAMLOCAL) 719 fwd.listen_path = listen_addr; 720 else 721 fwd.listen_host = listen_addr; 722 fwd.connect_port = cport; 723 if (fwd.connect_port == PORT_STREAMLOCAL) 724 fwd.connect_path = connect_addr; 725 else 726 fwd.connect_host = connect_addr; 727 728 debug2_f("channel %d: request %s", c->self, 729 (fwd_desc = format_forward(ftype, &fwd))); 730 731 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 732 ftype != MUX_FWD_DYNAMIC) { 733 logit_f("invalid forwarding type %u", ftype); 734 invalid: 735 free(listen_addr); 736 free(connect_addr); 737 reply_error(reply, MUX_S_FAILURE, rid, 738 "Invalid forwarding request"); 739 return 0; 740 } 741 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 742 logit_f("streamlocal and dynamic forwards " 743 "are mutually exclusive"); 744 goto invalid; 745 } 746 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 747 logit_f("invalid listen port %u", fwd.listen_port); 748 goto invalid; 749 } 750 if ((fwd.connect_port != PORT_STREAMLOCAL && 751 fwd.connect_port >= 65536) || 752 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 753 fwd.connect_port == 0)) { 754 logit_f("invalid connect port %u", 755 fwd.connect_port); 756 goto invalid; 757 } 758 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 759 fwd.connect_path == NULL) { 760 logit_f("missing connect host"); 761 goto invalid; 762 } 763 764 /* Skip forwards that have already been requested */ 765 switch (ftype) { 766 case MUX_FWD_LOCAL: 767 case MUX_FWD_DYNAMIC: 768 for (i = 0; i < options.num_local_forwards; i++) { 769 if (compare_forward(&fwd, 770 options.local_forwards + i)) { 771 exists: 772 debug2_f("found existing forwarding"); 773 reply_ok(reply, rid); 774 goto out; 775 } 776 } 777 break; 778 case MUX_FWD_REMOTE: 779 for (i = 0; i < options.num_remote_forwards; i++) { 780 if (!compare_forward(&fwd, options.remote_forwards + i)) 781 continue; 782 if (fwd.listen_port != 0) 783 goto exists; 784 debug2_f("found allocated port"); 785 if ((r = sshbuf_put_u32(reply, 786 MUX_S_REMOTE_PORT)) != 0 || 787 (r = sshbuf_put_u32(reply, rid)) != 0 || 788 (r = sshbuf_put_u32(reply, 789 options.remote_forwards[i].allocated_port)) != 0) 790 fatal_fr(r, "reply FWD_REMOTE"); 791 goto out; 792 } 793 break; 794 } 795 796 if (options.control_master == SSHCTL_MASTER_ASK || 797 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 798 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 799 debug2_f("forwarding refused by user"); 800 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 801 "Permission denied"); 802 goto out; 803 } 804 } 805 806 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 807 if (!channel_setup_local_fwd_listener(ssh, &fwd, 808 &options.fwd_opts)) { 809 fail: 810 logit_f("requested %s failed", fwd_desc); 811 reply_error(reply, MUX_S_FAILURE, rid, 812 "Port forwarding failed"); 813 goto out; 814 } 815 add_local_forward(&options, &fwd); 816 freefwd = 0; 817 } else { 818 struct mux_channel_confirm_ctx *fctx; 819 820 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 821 if (fwd.handle < 0) 822 goto fail; 823 add_remote_forward(&options, &fwd); 824 fctx = xcalloc(1, sizeof(*fctx)); 825 fctx->cid = c->self; 826 fctx->rid = rid; 827 fctx->fid = options.num_remote_forwards - 1; 828 client_register_global_confirm(mux_confirm_remote_forward, 829 fctx); 830 freefwd = 0; 831 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 832 /* delayed reply in mux_confirm_remote_forward */ 833 goto out; 834 } 835 reply_ok(reply, rid); 836 out: 837 free(fwd_desc); 838 if (freefwd) { 839 free(fwd.listen_host); 840 free(fwd.listen_path); 841 free(fwd.connect_host); 842 free(fwd.connect_path); 843 } 844 return ret; 845 } 846 847 static int 848 mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 849 Channel *c, struct sshbuf *m, struct sshbuf *reply) 850 { 851 struct Forward fwd, *found_fwd; 852 char *fwd_desc = NULL; 853 const char *error_reason = NULL; 854 char *listen_addr = NULL, *connect_addr = NULL; 855 u_int ftype; 856 int r, i, ret = 0; 857 u_int lport, cport; 858 859 memset(&fwd, 0, sizeof(fwd)); 860 861 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 862 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 863 (r = sshbuf_get_u32(m, &lport)) != 0 || 864 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 865 (r = sshbuf_get_u32(m, &cport)) != 0 || 866 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 867 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 868 error_f("malformed message"); 869 ret = -1; 870 goto out; 871 } 872 873 if (*listen_addr == '\0') { 874 free(listen_addr); 875 listen_addr = NULL; 876 } 877 if (*connect_addr == '\0') { 878 free(connect_addr); 879 connect_addr = NULL; 880 } 881 882 memset(&fwd, 0, sizeof(fwd)); 883 fwd.listen_port = lport; 884 if (fwd.listen_port == PORT_STREAMLOCAL) 885 fwd.listen_path = listen_addr; 886 else 887 fwd.listen_host = listen_addr; 888 fwd.connect_port = cport; 889 if (fwd.connect_port == PORT_STREAMLOCAL) 890 fwd.connect_path = connect_addr; 891 else 892 fwd.connect_host = connect_addr; 893 894 debug2_f("channel %d: request cancel %s", c->self, 895 (fwd_desc = format_forward(ftype, &fwd))); 896 897 /* make sure this has been requested */ 898 found_fwd = NULL; 899 switch (ftype) { 900 case MUX_FWD_LOCAL: 901 case MUX_FWD_DYNAMIC: 902 for (i = 0; i < options.num_local_forwards; i++) { 903 if (compare_forward(&fwd, 904 options.local_forwards + i)) { 905 found_fwd = options.local_forwards + i; 906 break; 907 } 908 } 909 break; 910 case MUX_FWD_REMOTE: 911 for (i = 0; i < options.num_remote_forwards; i++) { 912 if (compare_forward(&fwd, 913 options.remote_forwards + i)) { 914 found_fwd = options.remote_forwards + i; 915 break; 916 } 917 } 918 break; 919 } 920 921 if (found_fwd == NULL) 922 error_reason = "port not forwarded"; 923 else if (ftype == MUX_FWD_REMOTE) { 924 /* 925 * This shouldn't fail unless we confused the host/port 926 * between options.remote_forwards and permitted_opens. 927 * However, for dynamic allocated listen ports we need 928 * to use the actual listen port. 929 */ 930 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 931 error_reason = "port not in permitted opens"; 932 } else { /* local and dynamic forwards */ 933 /* Ditto */ 934 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 935 &options.fwd_opts) == -1) 936 error_reason = "port not found"; 937 } 938 939 if (error_reason != NULL) 940 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 941 else { 942 reply_ok(reply, rid); 943 free(found_fwd->listen_host); 944 free(found_fwd->listen_path); 945 free(found_fwd->connect_host); 946 free(found_fwd->connect_path); 947 found_fwd->listen_host = found_fwd->connect_host = NULL; 948 found_fwd->listen_path = found_fwd->connect_path = NULL; 949 found_fwd->listen_port = found_fwd->connect_port = 0; 950 } 951 out: 952 free(fwd_desc); 953 free(listen_addr); 954 free(connect_addr); 955 956 return ret; 957 } 958 959 static int 960 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 961 Channel *c, struct sshbuf *m, struct sshbuf *reply) 962 { 963 Channel *nc; 964 char *chost = NULL; 965 u_int _cport, i, j; 966 int ok = 0, cport, r, new_fd[2]; 967 struct mux_stdio_confirm_ctx *cctx; 968 969 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 970 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 971 (r = sshbuf_get_u32(m, &_cport)) != 0) { 972 free(chost); 973 error_f("malformed message"); 974 return -1; 975 } 976 if (_cport == (u_int)PORT_STREAMLOCAL) 977 cport = PORT_STREAMLOCAL; 978 else if (_cport <= INT_MAX) 979 cport = (int)_cport; 980 else { 981 free(chost); 982 error_f("invalid port 0x%x", _cport); 983 return -1; 984 } 985 986 debug2_f("channel %d: stdio fwd to %s:%d", c->self, chost, cport); 987 988 /* Gather fds from client */ 989 for(i = 0; i < 2; i++) { 990 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 991 error_f("failed to receive fd %d from client", i); 992 for (j = 0; j < i; j++) 993 close(new_fd[j]); 994 free(chost); 995 996 /* prepare reply */ 997 reply_error(reply, MUX_S_FAILURE, rid, 998 "did not receive file descriptors"); 999 return -1; 1000 } 1001 } 1002 1003 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 1004 1005 /* XXX support multiple child sessions in future */ 1006 if (c->have_remote_id) { 1007 debug2_f("session already open"); 1008 reply_error(reply, MUX_S_FAILURE, rid, 1009 "Multiple sessions not supported"); 1010 cleanup: 1011 close(new_fd[0]); 1012 close(new_fd[1]); 1013 free(chost); 1014 return 0; 1015 } 1016 1017 if (options.control_master == SSHCTL_MASTER_ASK || 1018 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1019 if (cport == PORT_STREAMLOCAL) { 1020 ok = ask_permission("Allow forward to path %s", chost); 1021 } else { 1022 ok = ask_permission("Allow forward to [%s]:%d? ", 1023 chost, cport); 1024 } 1025 if (!ok) { 1026 debug2_f("stdio fwd refused by user"); 1027 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1028 "Permission denied"); 1029 goto cleanup; 1030 } 1031 } 1032 1033 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1], 1034 CHANNEL_NONBLOCK_STDIO); 1035 free(chost); 1036 1037 nc->ctl_chan = c->self; /* link session -> control channel */ 1038 c->remote_id = nc->self; /* link control -> session channel */ 1039 c->have_remote_id = 1; 1040 1041 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan); 1042 1043 channel_register_cleanup(ssh, nc->self, 1044 mux_master_session_cleanup_cb, 1); 1045 1046 cctx = xcalloc(1, sizeof(*cctx)); 1047 cctx->rid = rid; 1048 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1049 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1050 1051 /* reply is deferred, sent by mux_session_confirm */ 1052 return 0; 1053 } 1054 1055 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1056 static void 1057 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1058 { 1059 struct mux_stdio_confirm_ctx *cctx = arg; 1060 Channel *c, *cc; 1061 struct sshbuf *reply; 1062 int r; 1063 1064 if (cctx == NULL) 1065 fatal_f("cctx == NULL"); 1066 if ((c = channel_by_id(ssh, id)) == NULL) 1067 fatal_f("no channel for id %d", id); 1068 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1069 fatal_f("channel %d lacks control channel %d", 1070 id, c->ctl_chan); 1071 if ((reply = sshbuf_new()) == NULL) 1072 fatal_f("sshbuf_new"); 1073 1074 if (!success) { 1075 debug3_f("sending failure reply"); 1076 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1077 "Session open refused by peer"); 1078 /* prepare reply */ 1079 goto done; 1080 } 1081 1082 debug3_f("sending success reply"); 1083 /* prepare reply */ 1084 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1085 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1086 (r = sshbuf_put_u32(reply, c->self)) != 0) 1087 fatal_fr(r, "reply"); 1088 1089 done: 1090 /* Send reply */ 1091 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1092 fatal_fr(r, "enqueue"); 1093 sshbuf_free(reply); 1094 1095 if (cc->mux_pause <= 0) 1096 fatal_f("mux_pause %d", cc->mux_pause); 1097 cc->mux_pause = 0; /* start processing messages again */ 1098 c->open_confirm_ctx = NULL; 1099 free(cctx); 1100 } 1101 1102 static int 1103 mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1104 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1105 { 1106 debug_f("channel %d: stop listening", c->self); 1107 1108 if (options.control_master == SSHCTL_MASTER_ASK || 1109 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1110 if (!ask_permission("Disable further multiplexing on shared " 1111 "connection to %s? ", host)) { 1112 debug2_f("stop listen refused by user"); 1113 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1114 "Permission denied"); 1115 return 0; 1116 } 1117 } 1118 1119 if (mux_listener_channel != NULL) { 1120 channel_free(ssh, mux_listener_channel); 1121 client_stop_mux(); 1122 free(options.control_path); 1123 options.control_path = NULL; 1124 mux_listener_channel = NULL; 1125 muxserver_sock = -1; 1126 } 1127 1128 reply_ok(reply, rid); 1129 return 0; 1130 } 1131 1132 static int 1133 mux_master_process_proxy(struct ssh *ssh, u_int rid, 1134 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1135 { 1136 int r; 1137 1138 debug_f("channel %d: proxy request", c->self); 1139 1140 c->mux_rcb = channel_proxy_downstream; 1141 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1142 (r = sshbuf_put_u32(reply, rid)) != 0) 1143 fatal_fr(r, "reply"); 1144 1145 return 0; 1146 } 1147 1148 /* Channel callbacks fired on read/write from mux client fd */ 1149 static int 1150 mux_master_read_cb(struct ssh *ssh, Channel *c) 1151 { 1152 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1153 struct sshbuf *in = NULL, *out = NULL; 1154 u_int type, rid, i; 1155 int r, ret = -1; 1156 1157 if ((out = sshbuf_new()) == NULL) 1158 fatal_f("sshbuf_new"); 1159 1160 /* Setup ctx and */ 1161 if (c->mux_ctx == NULL) { 1162 state = xcalloc(1, sizeof(*state)); 1163 c->mux_ctx = state; 1164 channel_register_cleanup(ssh, c->self, 1165 mux_master_control_cleanup_cb, 0); 1166 1167 /* Send hello */ 1168 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1169 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1170 fatal_fr(r, "reply"); 1171 /* no extensions */ 1172 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1173 fatal_fr(r, "enqueue"); 1174 debug3_f("channel %d: hello sent", c->self); 1175 ret = 0; 1176 goto out; 1177 } 1178 1179 /* Channel code ensures that we receive whole packets */ 1180 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1181 malf: 1182 error_f("malformed message"); 1183 goto out; 1184 } 1185 1186 if ((r = sshbuf_get_u32(in, &type)) != 0) 1187 goto malf; 1188 debug3_f("channel %d packet type 0x%08x len %zu", c->self, 1189 type, sshbuf_len(in)); 1190 1191 if (type == MUX_MSG_HELLO) 1192 rid = 0; 1193 else { 1194 if (!state->hello_rcvd) { 1195 error_f("expected MUX_MSG_HELLO(0x%08x), " 1196 "received 0x%08x", MUX_MSG_HELLO, type); 1197 goto out; 1198 } 1199 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1200 goto malf; 1201 } 1202 1203 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1204 if (type == mux_master_handlers[i].type) { 1205 ret = mux_master_handlers[i].handler(ssh, rid, 1206 c, in, out); 1207 break; 1208 } 1209 } 1210 if (mux_master_handlers[i].handler == NULL) { 1211 error_f("unsupported mux message 0x%08x", type); 1212 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1213 ret = 0; 1214 } 1215 /* Enqueue reply packet */ 1216 if (sshbuf_len(out) != 0 && 1217 (r = sshbuf_put_stringb(c->output, out)) != 0) 1218 fatal_fr(r, "enqueue"); 1219 out: 1220 sshbuf_free(in); 1221 sshbuf_free(out); 1222 return ret; 1223 } 1224 1225 void 1226 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1227 { 1228 struct sshbuf *m; 1229 Channel *mux_chan; 1230 int r; 1231 1232 debug3_f("channel %d: exit message, exitval %d", c->self, exitval); 1233 1234 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1235 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1236 1237 /* Append exit message packet to control socket output queue */ 1238 if ((m = sshbuf_new()) == NULL) 1239 fatal_f("sshbuf_new"); 1240 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1241 (r = sshbuf_put_u32(m, c->self)) != 0 || 1242 (r = sshbuf_put_u32(m, exitval)) != 0 || 1243 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1244 fatal_fr(r, "reply"); 1245 sshbuf_free(m); 1246 } 1247 1248 void 1249 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1250 { 1251 struct sshbuf *m; 1252 Channel *mux_chan; 1253 int r; 1254 1255 debug3_f("channel %d: TTY alloc failed", c->self); 1256 1257 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1258 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1259 1260 /* Append exit message packet to control socket output queue */ 1261 if ((m = sshbuf_new()) == NULL) 1262 fatal_f("sshbuf_new"); 1263 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1264 (r = sshbuf_put_u32(m, c->self)) != 0 || 1265 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1266 fatal_fr(r, "reply"); 1267 sshbuf_free(m); 1268 } 1269 1270 /* Prepare a mux master to listen on a Unix domain socket. */ 1271 void 1272 muxserver_listen(struct ssh *ssh) 1273 { 1274 mode_t old_umask; 1275 char *orig_control_path = options.control_path; 1276 char rbuf[16+1]; 1277 u_int i, r; 1278 int oerrno; 1279 1280 if (options.control_path == NULL || 1281 options.control_master == SSHCTL_MASTER_NO) 1282 return; 1283 1284 debug("setting up multiplex master socket"); 1285 1286 /* 1287 * Use a temporary path before listen so we can pseudo-atomically 1288 * establish the listening socket in its final location to avoid 1289 * other processes racing in between bind() and listen() and hitting 1290 * an unready socket. 1291 */ 1292 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1293 r = arc4random_uniform(26+26+10); 1294 rbuf[i] = (r < 26) ? 'a' + r : 1295 (r < 26*2) ? 'A' + r - 26 : 1296 '0' + r - 26 - 26; 1297 } 1298 rbuf[sizeof(rbuf) - 1] = '\0'; 1299 options.control_path = NULL; 1300 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1301 debug3_f("temporary control path %s", options.control_path); 1302 1303 old_umask = umask(0177); 1304 muxserver_sock = unix_listener(options.control_path, 64, 0); 1305 oerrno = errno; 1306 umask(old_umask); 1307 if (muxserver_sock < 0) { 1308 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1309 error("ControlSocket %s already exists, " 1310 "disabling multiplexing", options.control_path); 1311 disable_mux_master: 1312 if (muxserver_sock != -1) { 1313 close(muxserver_sock); 1314 muxserver_sock = -1; 1315 } 1316 free(orig_control_path); 1317 free(options.control_path); 1318 options.control_path = NULL; 1319 options.control_master = SSHCTL_MASTER_NO; 1320 return; 1321 } else { 1322 /* unix_listener() logs the error */ 1323 cleanup_exit(255); 1324 } 1325 } 1326 1327 /* Now atomically "move" the mux socket into position */ 1328 if (link(options.control_path, orig_control_path) != 0) { 1329 if (errno != EEXIST) { 1330 fatal_f("link mux listener %s => %s: %s", 1331 options.control_path, orig_control_path, 1332 strerror(errno)); 1333 } 1334 error("ControlSocket %s already exists, disabling multiplexing", 1335 orig_control_path); 1336 unlink(options.control_path); 1337 goto disable_mux_master; 1338 } 1339 unlink(options.control_path); 1340 free(options.control_path); 1341 options.control_path = orig_control_path; 1342 1343 set_nonblock(muxserver_sock); 1344 1345 mux_listener_channel = channel_new(ssh, "mux listener", 1346 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1347 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1348 0, options.control_path, 1); 1349 mux_listener_channel->mux_rcb = mux_master_read_cb; 1350 debug3_f("mux listener channel %d fd %d", 1351 mux_listener_channel->self, mux_listener_channel->sock); 1352 } 1353 1354 /* Callback on open confirmation in mux master for a mux client session. */ 1355 static void 1356 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1357 { 1358 struct mux_session_confirm_ctx *cctx = arg; 1359 const char *display; 1360 Channel *c, *cc; 1361 int i, r; 1362 struct sshbuf *reply; 1363 1364 if (cctx == NULL) 1365 fatal_f("cctx == NULL"); 1366 if ((c = channel_by_id(ssh, id)) == NULL) 1367 fatal_f("no channel for id %d", id); 1368 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1369 fatal_f("channel %d lacks control channel %d", 1370 id, c->ctl_chan); 1371 if ((reply = sshbuf_new()) == NULL) 1372 fatal_f("sshbuf_new"); 1373 1374 if (!success) { 1375 debug3_f("sending failure reply"); 1376 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1377 "Session open refused by peer"); 1378 goto done; 1379 } 1380 1381 display = getenv("DISPLAY"); 1382 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1383 char *proto, *data; 1384 1385 /* Get reasonable local authentication information. */ 1386 if (client_x11_get_proto(ssh, display, options.xauth_location, 1387 options.forward_x11_trusted, options.forward_x11_timeout, 1388 &proto, &data) == 0) { 1389 /* Request forwarding with authentication spoofing. */ 1390 debug("Requesting X11 forwarding with authentication " 1391 "spoofing."); 1392 x11_request_forwarding_with_spoofing(ssh, id, 1393 display, proto, data, 1); 1394 /* XXX exit_on_forward_failure */ 1395 client_expect_confirm(ssh, id, "X11 forwarding", 1396 CONFIRM_WARN); 1397 } 1398 } 1399 1400 if (cctx->want_agent_fwd && options.forward_agent) { 1401 debug("Requesting authentication agent forwarding."); 1402 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1403 if ((r = sshpkt_send(ssh)) != 0) 1404 fatal_fr(r, "send"); 1405 } 1406 1407 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1408 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1409 1410 debug3_f("sending success reply"); 1411 /* prepare reply */ 1412 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1413 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1414 (r = sshbuf_put_u32(reply, c->self)) != 0) 1415 fatal_fr(r, "reply"); 1416 1417 done: 1418 /* Send reply */ 1419 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1420 fatal_fr(r, "enqueue"); 1421 sshbuf_free(reply); 1422 1423 if (cc->mux_pause <= 0) 1424 fatal_f("mux_pause %d", cc->mux_pause); 1425 cc->mux_pause = 0; /* start processing messages again */ 1426 c->open_confirm_ctx = NULL; 1427 sshbuf_free(cctx->cmd); 1428 free(cctx->term); 1429 if (cctx->env != NULL) { 1430 for (i = 0; cctx->env[i] != NULL; i++) 1431 free(cctx->env[i]); 1432 free(cctx->env); 1433 } 1434 free(cctx); 1435 } 1436 1437 /* ** Multiplexing client support */ 1438 1439 /* Exit signal handler */ 1440 static void 1441 control_client_sighandler(int signo) 1442 { 1443 muxclient_terminate = signo; 1444 } 1445 1446 /* 1447 * Relay signal handler - used to pass some signals from mux client to 1448 * mux master. 1449 */ 1450 static void 1451 control_client_sigrelay(int signo) 1452 { 1453 int save_errno = errno; 1454 1455 if (muxserver_pid > 1) 1456 kill(muxserver_pid, signo); 1457 1458 errno = save_errno; 1459 } 1460 1461 static int 1462 mux_client_read(int fd, struct sshbuf *b, size_t need, int timeout_ms) 1463 { 1464 size_t have; 1465 ssize_t len; 1466 u_char *p; 1467 int r; 1468 1469 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1470 fatal_fr(r, "reserve"); 1471 for (have = 0; have < need; ) { 1472 if (muxclient_terminate) { 1473 errno = EINTR; 1474 return -1; 1475 } 1476 len = read(fd, p + have, need - have); 1477 if (len == -1) { 1478 switch (errno) { 1479 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1480 case EWOULDBLOCK: 1481 #endif 1482 case EAGAIN: 1483 if (waitrfd(fd, &timeout_ms, 1484 &muxclient_terminate) == -1 && 1485 errno != EINTR) 1486 return -1; /* timeout */ 1487 /* FALLTHROUGH */ 1488 case EINTR: 1489 continue; 1490 default: 1491 return -1; 1492 } 1493 } 1494 if (len == 0) { 1495 errno = EPIPE; 1496 return -1; 1497 } 1498 have += (size_t)len; 1499 } 1500 return 0; 1501 } 1502 1503 static int 1504 mux_client_write_packet(int fd, struct sshbuf *m) 1505 { 1506 struct sshbuf *queue; 1507 u_int have, need; 1508 int r, oerrno, len; 1509 const u_char *ptr; 1510 struct pollfd pfd; 1511 1512 pfd.fd = fd; 1513 pfd.events = POLLOUT; 1514 if ((queue = sshbuf_new()) == NULL) 1515 fatal_f("sshbuf_new"); 1516 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1517 fatal_fr(r, "enqueue"); 1518 1519 need = sshbuf_len(queue); 1520 ptr = sshbuf_ptr(queue); 1521 1522 for (have = 0; have < need; ) { 1523 if (muxclient_terminate) { 1524 sshbuf_free(queue); 1525 errno = EINTR; 1526 return -1; 1527 } 1528 len = write(fd, ptr + have, need - have); 1529 if (len == -1) { 1530 switch (errno) { 1531 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1532 case EWOULDBLOCK: 1533 #endif 1534 case EAGAIN: 1535 (void)poll(&pfd, 1, -1); 1536 /* FALLTHROUGH */ 1537 case EINTR: 1538 continue; 1539 default: 1540 oerrno = errno; 1541 sshbuf_free(queue); 1542 errno = oerrno; 1543 return -1; 1544 } 1545 } 1546 if (len == 0) { 1547 sshbuf_free(queue); 1548 errno = EPIPE; 1549 return -1; 1550 } 1551 have += (u_int)len; 1552 } 1553 sshbuf_free(queue); 1554 return 0; 1555 } 1556 1557 static int 1558 mux_client_read_packet_timeout(int fd, struct sshbuf *m, int timeout_ms) 1559 { 1560 struct sshbuf *queue; 1561 size_t need, have; 1562 const u_char *ptr; 1563 int r, oerrno; 1564 1565 if ((queue = sshbuf_new()) == NULL) 1566 fatal_f("sshbuf_new"); 1567 if (mux_client_read(fd, queue, 4, timeout_ms) != 0) { 1568 if ((oerrno = errno) == EPIPE) 1569 debug3_f("read header failed: %s", 1570 strerror(errno)); 1571 sshbuf_free(queue); 1572 errno = oerrno; 1573 return -1; 1574 } 1575 need = PEEK_U32(sshbuf_ptr(queue)); 1576 if (mux_client_read(fd, queue, need, timeout_ms) != 0) { 1577 oerrno = errno; 1578 debug3_f("read body failed: %s", strerror(errno)); 1579 sshbuf_free(queue); 1580 errno = oerrno; 1581 return -1; 1582 } 1583 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1584 (r = sshbuf_put(m, ptr, have)) != 0) 1585 fatal_fr(r, "dequeue"); 1586 sshbuf_free(queue); 1587 return 0; 1588 } 1589 1590 static int 1591 mux_client_read_packet(int fd, struct sshbuf *m) 1592 { 1593 return mux_client_read_packet_timeout(fd, m, -1); 1594 } 1595 1596 static int 1597 mux_client_hello_exchange(int fd, int timeout_ms) 1598 { 1599 struct sshbuf *m; 1600 u_int type, ver; 1601 int r, ret = -1; 1602 1603 if ((m = sshbuf_new()) == NULL) 1604 fatal_f("sshbuf_new"); 1605 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1606 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1607 fatal_fr(r, "assemble hello"); 1608 /* no extensions */ 1609 1610 if (mux_client_write_packet(fd, m) != 0) { 1611 debug_f("write packet: %s", strerror(errno)); 1612 goto out; 1613 } 1614 1615 sshbuf_reset(m); 1616 1617 /* Read their HELLO */ 1618 if (mux_client_read_packet_timeout(fd, m, timeout_ms) != 0) { 1619 debug_f("read packet failed"); 1620 goto out; 1621 } 1622 1623 if ((r = sshbuf_get_u32(m, &type)) != 0) 1624 fatal_fr(r, "parse type"); 1625 if (type != MUX_MSG_HELLO) { 1626 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1627 goto out; 1628 } 1629 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1630 fatal_fr(r, "parse version"); 1631 if (ver != SSHMUX_VER) { 1632 error("Unsupported multiplexing protocol version %d " 1633 "(expected %d)", ver, SSHMUX_VER); 1634 goto out; 1635 } 1636 debug2_f("master version %u", ver); 1637 /* No extensions are presently defined */ 1638 while (sshbuf_len(m) > 0) { 1639 char *name = NULL; 1640 1641 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1642 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1643 error_fr(r, "parse extension"); 1644 goto out; 1645 } 1646 debug2("Unrecognised master extension \"%s\"", name); 1647 free(name); 1648 } 1649 /* success */ 1650 ret = 0; 1651 out: 1652 sshbuf_free(m); 1653 return ret; 1654 } 1655 1656 static u_int 1657 mux_client_request_alive(int fd) 1658 { 1659 struct sshbuf *m; 1660 char *e; 1661 u_int pid, type, rid; 1662 int r; 1663 1664 debug3_f("entering"); 1665 1666 if ((m = sshbuf_new()) == NULL) 1667 fatal_f("sshbuf_new"); 1668 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1669 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1670 fatal_fr(r, "assemble"); 1671 1672 if (mux_client_write_packet(fd, m) != 0) 1673 fatal_f("write packet: %s", strerror(errno)); 1674 1675 sshbuf_reset(m); 1676 1677 /* Read their reply */ 1678 if (mux_client_read_packet(fd, m) != 0) { 1679 sshbuf_free(m); 1680 return 0; 1681 } 1682 1683 if ((r = sshbuf_get_u32(m, &type)) != 0) 1684 fatal_fr(r, "parse type"); 1685 if (type != MUX_S_ALIVE) { 1686 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1687 fatal_fr(r, "parse error message"); 1688 fatal_f("master returned error: %s", e); 1689 } 1690 1691 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1692 fatal_fr(r, "parse remote ID"); 1693 if (rid != muxclient_request_id) 1694 fatal_f("out of sequence reply: my id %u theirs %u", 1695 muxclient_request_id, rid); 1696 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1697 fatal_fr(r, "parse PID"); 1698 sshbuf_free(m); 1699 1700 debug3_f("done pid = %u", pid); 1701 1702 muxclient_request_id++; 1703 1704 return pid; 1705 } 1706 1707 static void 1708 mux_client_request_terminate(int fd) 1709 { 1710 struct sshbuf *m; 1711 char *e; 1712 u_int type, rid; 1713 int r; 1714 1715 debug3_f("entering"); 1716 1717 if ((m = sshbuf_new()) == NULL) 1718 fatal_f("sshbuf_new"); 1719 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1720 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1721 fatal_fr(r, "request"); 1722 1723 if (mux_client_write_packet(fd, m) != 0) 1724 fatal_f("write packet: %s", strerror(errno)); 1725 1726 sshbuf_reset(m); 1727 1728 /* Read their reply */ 1729 if (mux_client_read_packet(fd, m) != 0) { 1730 /* Remote end exited already */ 1731 if (errno == EPIPE) { 1732 sshbuf_free(m); 1733 return; 1734 } 1735 fatal_f("read from master failed: %s", strerror(errno)); 1736 } 1737 1738 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1739 (r = sshbuf_get_u32(m, &rid)) != 0) 1740 fatal_fr(r, "parse"); 1741 if (rid != muxclient_request_id) 1742 fatal_f("out of sequence reply: my id %u theirs %u", 1743 muxclient_request_id, rid); 1744 switch (type) { 1745 case MUX_S_OK: 1746 break; 1747 case MUX_S_PERMISSION_DENIED: 1748 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1749 fatal_fr(r, "parse error message"); 1750 fatal("Master refused termination request: %s", e); 1751 case MUX_S_FAILURE: 1752 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1753 fatal_fr(r, "parse error message"); 1754 fatal_f("termination request failed: %s", e); 1755 default: 1756 fatal_f("unexpected response from master 0x%08x", type); 1757 } 1758 sshbuf_free(m); 1759 muxclient_request_id++; 1760 } 1761 1762 static int 1763 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1764 { 1765 struct sshbuf *m; 1766 char *e, *fwd_desc; 1767 const char *lhost, *chost; 1768 u_int type, rid; 1769 int r; 1770 1771 fwd_desc = format_forward(ftype, fwd); 1772 debug("Requesting %s %s", 1773 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1774 free(fwd_desc); 1775 1776 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1777 if (fwd->listen_path != NULL) 1778 lhost = fwd->listen_path; 1779 else if (fwd->listen_host == NULL) 1780 lhost = ""; 1781 else if (*fwd->listen_host == '\0') 1782 lhost = "*"; 1783 else 1784 lhost = fwd->listen_host; 1785 1786 if (fwd->connect_path != NULL) 1787 chost = fwd->connect_path; 1788 else if (fwd->connect_host == NULL) 1789 chost = ""; 1790 else 1791 chost = fwd->connect_host; 1792 1793 if ((m = sshbuf_new()) == NULL) 1794 fatal_f("sshbuf_new"); 1795 if ((r = sshbuf_put_u32(m, type)) != 0 || 1796 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1797 (r = sshbuf_put_u32(m, ftype)) != 0 || 1798 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1799 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1800 (r = sshbuf_put_cstring(m, chost)) != 0 || 1801 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1802 fatal_fr(r, "request"); 1803 1804 if (mux_client_write_packet(fd, m) != 0) 1805 fatal_f("write packet: %s", strerror(errno)); 1806 1807 sshbuf_reset(m); 1808 1809 /* Read their reply */ 1810 if (mux_client_read_packet(fd, m) != 0) { 1811 sshbuf_free(m); 1812 return -1; 1813 } 1814 1815 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1816 (r = sshbuf_get_u32(m, &rid)) != 0) 1817 fatal_fr(r, "parse"); 1818 if (rid != muxclient_request_id) 1819 fatal_f("out of sequence reply: my id %u theirs %u", 1820 muxclient_request_id, rid); 1821 1822 switch (type) { 1823 case MUX_S_OK: 1824 break; 1825 case MUX_S_REMOTE_PORT: 1826 if (cancel_flag) 1827 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1828 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1829 fatal_fr(r, "parse port"); 1830 verbose("Allocated port %u for remote forward to %s:%d", 1831 fwd->allocated_port, 1832 fwd->connect_host ? fwd->connect_host : "", 1833 fwd->connect_port); 1834 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1835 fprintf(stdout, "%i\n", fwd->allocated_port); 1836 break; 1837 case MUX_S_PERMISSION_DENIED: 1838 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1839 fatal_fr(r, "parse error message"); 1840 sshbuf_free(m); 1841 error("Master refused forwarding request: %s", e); 1842 return -1; 1843 case MUX_S_FAILURE: 1844 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1845 fatal_fr(r, "parse error message"); 1846 sshbuf_free(m); 1847 error_f("forwarding request failed: %s", e); 1848 return -1; 1849 default: 1850 fatal_f("unexpected response from master 0x%08x", type); 1851 } 1852 sshbuf_free(m); 1853 1854 muxclient_request_id++; 1855 return 0; 1856 } 1857 1858 static int 1859 mux_client_forwards(int fd, int cancel_flag) 1860 { 1861 int i, ret = 0; 1862 1863 debug3_f("%s forwardings: %d local, %d remote", 1864 cancel_flag ? "cancel" : "request", 1865 options.num_local_forwards, options.num_remote_forwards); 1866 1867 /* XXX ExitOnForwardingFailure */ 1868 for (i = 0; i < options.num_local_forwards; i++) { 1869 if (mux_client_forward(fd, cancel_flag, 1870 options.local_forwards[i].connect_port == 0 ? 1871 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1872 options.local_forwards + i) != 0) 1873 ret = -1; 1874 } 1875 for (i = 0; i < options.num_remote_forwards; i++) { 1876 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1877 options.remote_forwards + i) != 0) 1878 ret = -1; 1879 } 1880 return ret; 1881 } 1882 1883 static int 1884 mux_client_request_session(int fd) 1885 { 1886 struct sshbuf *m; 1887 char *e; 1888 const char *term = NULL; 1889 u_int i, echar, rid, sid, esid, exitval, type, exitval_seen; 1890 extern char **environ; 1891 int r, rawmode = 0; 1892 1893 debug3_f("entering"); 1894 1895 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1896 error_f("master alive request failed"); 1897 return -1; 1898 } 1899 1900 ssh_signal(SIGPIPE, SIG_IGN); 1901 1902 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 1903 fatal_f("stdfd_devnull failed"); 1904 1905 if ((term = lookup_env_in_list("TERM", options.setenv, 1906 options.num_setenv)) == NULL || *term == '\0') 1907 term = getenv("TERM"); 1908 1909 echar = 0xffffffff; 1910 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1911 echar = (u_int)options.escape_char; 1912 1913 if ((m = sshbuf_new()) == NULL) 1914 fatal_f("sshbuf_new"); 1915 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1916 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1917 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1918 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1919 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1920 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1921 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 || 1922 (r = sshbuf_put_u32(m, echar)) != 0 || 1923 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 || 1924 (r = sshbuf_put_stringb(m, command)) != 0) 1925 fatal_fr(r, "request"); 1926 1927 /* Pass environment */ 1928 if (options.num_send_env > 0 && environ != NULL) { 1929 for (i = 0; environ[i] != NULL; i++) { 1930 if (!env_permitted(environ[i])) 1931 continue; 1932 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1933 fatal_fr(r, "request sendenv"); 1934 } 1935 } 1936 for (i = 0; i < options.num_setenv; i++) { 1937 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1938 fatal_fr(r, "request setenv"); 1939 } 1940 1941 if (mux_client_write_packet(fd, m) != 0) 1942 fatal_f("write packet: %s", strerror(errno)); 1943 1944 /* Send the stdio file descriptors */ 1945 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1946 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1947 mm_send_fd(fd, STDERR_FILENO) == -1) 1948 fatal_f("send fds failed"); 1949 1950 debug3_f("session request sent"); 1951 1952 /* Read their reply */ 1953 sshbuf_reset(m); 1954 if (mux_client_read_packet(fd, m) != 0) { 1955 error_f("read from master failed: %s", strerror(errno)); 1956 sshbuf_free(m); 1957 return -1; 1958 } 1959 1960 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1961 (r = sshbuf_get_u32(m, &rid)) != 0) 1962 fatal_fr(r, "parse"); 1963 if (rid != muxclient_request_id) 1964 fatal_f("out of sequence reply: my id %u theirs %u", 1965 muxclient_request_id, rid); 1966 1967 switch (type) { 1968 case MUX_S_SESSION_OPENED: 1969 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1970 fatal_fr(r, "parse session ID"); 1971 debug_f("master session id: %u", sid); 1972 break; 1973 case MUX_S_PERMISSION_DENIED: 1974 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1975 fatal_fr(r, "parse error message"); 1976 error("Master refused session request: %s", e); 1977 sshbuf_free(m); 1978 return -1; 1979 case MUX_S_FAILURE: 1980 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1981 fatal_fr(r, "parse error message"); 1982 error_f("session request failed: %s", e); 1983 sshbuf_free(m); 1984 return -1; 1985 default: 1986 sshbuf_free(m); 1987 error_f("unexpected response from master 0x%08x", type); 1988 return -1; 1989 } 1990 muxclient_request_id++; 1991 1992 if (pledge("stdio proc tty", NULL) == -1) 1993 fatal_f("pledge(): %s", strerror(errno)); 1994 platform_pledge_mux(); 1995 1996 ssh_signal(SIGHUP, control_client_sighandler); 1997 ssh_signal(SIGINT, control_client_sighandler); 1998 ssh_signal(SIGTERM, control_client_sighandler); 1999 ssh_signal(SIGWINCH, control_client_sigrelay); 2000 2001 if (options.fork_after_authentication) 2002 daemon(1, 1); 2003 else { 2004 rawmode = tty_flag; 2005 if (tty_flag) { 2006 enter_raw_mode( 2007 options.request_tty == REQUEST_TTY_FORCE); 2008 } 2009 } 2010 2011 /* 2012 * Stick around until the controlee closes the client_fd. 2013 * Before it does, it is expected to write an exit message. 2014 * This process must read the value and wait for the closure of 2015 * the client_fd; if this one closes early, the multiplex master will 2016 * terminate early too (possibly losing data). 2017 */ 2018 for (exitval = 255, exitval_seen = 0;;) { 2019 sshbuf_reset(m); 2020 if (mux_client_read_packet(fd, m) != 0) 2021 break; 2022 if ((r = sshbuf_get_u32(m, &type)) != 0) 2023 fatal_fr(r, "parse type"); 2024 switch (type) { 2025 case MUX_S_TTY_ALLOC_FAIL: 2026 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2027 fatal_fr(r, "parse session ID"); 2028 if (esid != sid) 2029 fatal_f("tty alloc fail on unknown session: " 2030 "my id %u theirs %u", sid, esid); 2031 leave_raw_mode(options.request_tty == 2032 REQUEST_TTY_FORCE); 2033 rawmode = 0; 2034 continue; 2035 case MUX_S_EXIT_MESSAGE: 2036 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2037 fatal_fr(r, "parse session ID"); 2038 if (esid != sid) 2039 fatal_f("exit on unknown session: " 2040 "my id %u theirs %u", sid, esid); 2041 if (exitval_seen) 2042 fatal_f("exitval sent twice"); 2043 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2044 fatal_fr(r, "parse exitval"); 2045 exitval_seen = 1; 2046 continue; 2047 default: 2048 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2049 fatal_fr(r, "parse error message"); 2050 fatal_f("master returned error: %s", e); 2051 } 2052 } 2053 2054 close(fd); 2055 if (rawmode) 2056 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2057 2058 if (muxclient_terminate) { 2059 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2060 exitval = 255; 2061 } else if (!exitval_seen) { 2062 debug2("Control master terminated unexpectedly"); 2063 exitval = 255; 2064 } else 2065 debug2("Received exit status from master %d", exitval); 2066 2067 if (tty_flag && options.log_level >= SYSLOG_LEVEL_INFO) 2068 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2069 2070 exit(exitval); 2071 } 2072 2073 static int 2074 mux_client_proxy(int fd) 2075 { 2076 struct sshbuf *m; 2077 char *e; 2078 u_int type, rid; 2079 int r; 2080 2081 if ((m = sshbuf_new()) == NULL) 2082 fatal_f("sshbuf_new"); 2083 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2084 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2085 fatal_fr(r, "request"); 2086 if (mux_client_write_packet(fd, m) != 0) 2087 fatal_f("write packet: %s", strerror(errno)); 2088 2089 sshbuf_reset(m); 2090 2091 /* Read their reply */ 2092 if (mux_client_read_packet(fd, m) != 0) { 2093 sshbuf_free(m); 2094 return 0; 2095 } 2096 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2097 (r = sshbuf_get_u32(m, &rid)) != 0) 2098 fatal_fr(r, "parse"); 2099 if (rid != muxclient_request_id) 2100 fatal_f("out of sequence reply: my id %u theirs %u", 2101 muxclient_request_id, rid); 2102 if (type != MUX_S_PROXY) { 2103 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2104 fatal_fr(r, "parse error message"); 2105 fatal_f("master returned error: %s", e); 2106 } 2107 sshbuf_free(m); 2108 2109 debug3_f("done"); 2110 muxclient_request_id++; 2111 return 0; 2112 } 2113 2114 static int 2115 mux_client_request_stdio_fwd(int fd) 2116 { 2117 struct sshbuf *m; 2118 char *e; 2119 u_int type, rid, sid; 2120 int r; 2121 2122 debug3_f("entering"); 2123 2124 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2125 error_f("master alive request failed"); 2126 return -1; 2127 } 2128 2129 ssh_signal(SIGPIPE, SIG_IGN); 2130 2131 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 2132 fatal_f("stdfd_devnull failed"); 2133 2134 if ((m = sshbuf_new()) == NULL) 2135 fatal_f("sshbuf_new"); 2136 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2137 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2138 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2139 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2140 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2141 fatal_fr(r, "request"); 2142 2143 if (mux_client_write_packet(fd, m) != 0) 2144 fatal_f("write packet: %s", strerror(errno)); 2145 2146 /* Send the stdio file descriptors */ 2147 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2148 mm_send_fd(fd, STDOUT_FILENO) == -1) 2149 fatal_f("send fds failed"); 2150 2151 if (pledge("stdio proc tty", NULL) == -1) 2152 fatal_f("pledge(): %s", strerror(errno)); 2153 platform_pledge_mux(); 2154 2155 debug3_f("stdio forward request sent"); 2156 2157 /* Read their reply */ 2158 sshbuf_reset(m); 2159 2160 if (mux_client_read_packet(fd, m) != 0) { 2161 error_f("read from master failed: %s", strerror(errno)); 2162 sshbuf_free(m); 2163 return -1; 2164 } 2165 2166 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2167 (r = sshbuf_get_u32(m, &rid)) != 0) 2168 fatal_fr(r, "parse"); 2169 if (rid != muxclient_request_id) 2170 fatal_f("out of sequence reply: my id %u theirs %u", 2171 muxclient_request_id, rid); 2172 switch (type) { 2173 case MUX_S_SESSION_OPENED: 2174 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2175 fatal_fr(r, "parse session ID"); 2176 debug_f("master session id: %u", sid); 2177 break; 2178 case MUX_S_PERMISSION_DENIED: 2179 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2180 fatal_fr(r, "parse error message"); 2181 sshbuf_free(m); 2182 fatal("Master refused stdio forwarding request: %s", e); 2183 case MUX_S_FAILURE: 2184 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2185 fatal_fr(r, "parse error message"); 2186 sshbuf_free(m); 2187 fatal("Stdio forwarding request failed: %s", e); 2188 default: 2189 sshbuf_free(m); 2190 error_f("unexpected response from master 0x%08x", type); 2191 return -1; 2192 } 2193 muxclient_request_id++; 2194 2195 ssh_signal(SIGHUP, control_client_sighandler); 2196 ssh_signal(SIGINT, control_client_sighandler); 2197 ssh_signal(SIGTERM, control_client_sighandler); 2198 ssh_signal(SIGWINCH, control_client_sigrelay); 2199 2200 /* 2201 * Stick around until the controlee closes the client_fd. 2202 */ 2203 sshbuf_reset(m); 2204 if (mux_client_read_packet(fd, m) != 0) { 2205 if (errno == EPIPE || 2206 (errno == EINTR && muxclient_terminate != 0)) 2207 return 0; 2208 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2209 } 2210 fatal_f("master returned unexpected message %u", type); 2211 } 2212 2213 static void 2214 mux_client_request_stop_listening(int fd) 2215 { 2216 struct sshbuf *m; 2217 char *e; 2218 u_int type, rid; 2219 int r; 2220 2221 debug3_f("entering"); 2222 2223 if ((m = sshbuf_new()) == NULL) 2224 fatal_f("sshbuf_new"); 2225 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2226 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2227 fatal_fr(r, "request"); 2228 2229 if (mux_client_write_packet(fd, m) != 0) 2230 fatal_f("write packet: %s", strerror(errno)); 2231 2232 sshbuf_reset(m); 2233 2234 /* Read their reply */ 2235 if (mux_client_read_packet(fd, m) != 0) 2236 fatal_f("read from master failed: %s", strerror(errno)); 2237 2238 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2239 (r = sshbuf_get_u32(m, &rid)) != 0) 2240 fatal_fr(r, "parse"); 2241 if (rid != muxclient_request_id) 2242 fatal_f("out of sequence reply: my id %u theirs %u", 2243 muxclient_request_id, rid); 2244 2245 switch (type) { 2246 case MUX_S_OK: 2247 break; 2248 case MUX_S_PERMISSION_DENIED: 2249 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2250 fatal_fr(r, "parse error message"); 2251 fatal("Master refused stop listening request: %s", e); 2252 case MUX_S_FAILURE: 2253 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2254 fatal_fr(r, "parse error message"); 2255 fatal_f("stop listening request failed: %s", e); 2256 default: 2257 fatal_f("unexpected response from master 0x%08x", type); 2258 } 2259 sshbuf_free(m); 2260 muxclient_request_id++; 2261 } 2262 2263 /* Multiplex client main loop. */ 2264 int 2265 muxclient(const char *path) 2266 { 2267 struct sockaddr_un addr; 2268 int sock, timeout = options.connection_timeout, timeout_ms = -1; 2269 u_int pid; 2270 2271 if (muxclient_command == 0) { 2272 if (options.stdio_forward_host != NULL) 2273 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2274 else 2275 muxclient_command = SSHMUX_COMMAND_OPEN; 2276 } 2277 2278 switch (options.control_master) { 2279 case SSHCTL_MASTER_AUTO: 2280 case SSHCTL_MASTER_AUTO_ASK: 2281 debug("auto-mux: Trying existing master at '%s'", path); 2282 /* FALLTHROUGH */ 2283 case SSHCTL_MASTER_NO: 2284 break; 2285 default: 2286 return -1; 2287 } 2288 2289 memset(&addr, '\0', sizeof(addr)); 2290 addr.sun_family = AF_UNIX; 2291 2292 if (strlcpy(addr.sun_path, path, 2293 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2294 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2295 (unsigned int)sizeof(addr.sun_path)); 2296 2297 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2298 fatal_f("socket(): %s", strerror(errno)); 2299 2300 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2301 switch (muxclient_command) { 2302 case SSHMUX_COMMAND_OPEN: 2303 case SSHMUX_COMMAND_STDIO_FWD: 2304 break; 2305 default: 2306 fatal("Control socket connect(%.100s): %s", path, 2307 strerror(errno)); 2308 } 2309 if (errno == ECONNREFUSED && 2310 options.control_master != SSHCTL_MASTER_NO) { 2311 debug("Stale control socket %.100s, unlinking", path); 2312 unlink(path); 2313 } else if (errno == ENOENT) { 2314 debug("Control socket \"%.100s\" does not exist", path); 2315 } else { 2316 error("Control socket connect(%.100s): %s", path, 2317 strerror(errno)); 2318 } 2319 close(sock); 2320 return -1; 2321 } 2322 set_nonblock(sock); 2323 2324 /* Timeout on initial connection only. */ 2325 if (timeout > 0 && timeout < INT_MAX / 1000) 2326 timeout_ms = timeout * 1000; 2327 2328 if (mux_client_hello_exchange(sock, timeout_ms) != 0) { 2329 error_f("master hello exchange failed"); 2330 close(sock); 2331 return -1; 2332 } 2333 2334 switch (muxclient_command) { 2335 case SSHMUX_COMMAND_ALIVE_CHECK: 2336 if ((pid = mux_client_request_alive(sock)) == 0) 2337 fatal_f("master alive check failed"); 2338 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2339 exit(0); 2340 case SSHMUX_COMMAND_TERMINATE: 2341 mux_client_request_terminate(sock); 2342 if (options.log_level != SYSLOG_LEVEL_QUIET) 2343 fprintf(stderr, "Exit request sent.\r\n"); 2344 exit(0); 2345 case SSHMUX_COMMAND_FORWARD: 2346 if (mux_client_forwards(sock, 0) != 0) 2347 fatal_f("master forward request failed"); 2348 exit(0); 2349 case SSHMUX_COMMAND_OPEN: 2350 if (mux_client_forwards(sock, 0) != 0) { 2351 error_f("master forward request failed"); 2352 return -1; 2353 } 2354 mux_client_request_session(sock); 2355 return -1; 2356 case SSHMUX_COMMAND_STDIO_FWD: 2357 mux_client_request_stdio_fwd(sock); 2358 exit(0); 2359 case SSHMUX_COMMAND_STOP: 2360 mux_client_request_stop_listening(sock); 2361 if (options.log_level != SYSLOG_LEVEL_QUIET) 2362 fprintf(stderr, "Stop listening request sent.\r\n"); 2363 exit(0); 2364 case SSHMUX_COMMAND_CANCEL_FWD: 2365 if (mux_client_forwards(sock, 1) != 0) 2366 error_f("master cancel forward request failed"); 2367 exit(0); 2368 case SSHMUX_COMMAND_PROXY: 2369 mux_client_proxy(sock); 2370 return (sock); 2371 default: 2372 fatal("unrecognised muxclient_command %d", muxclient_command); 2373 } 2374 } 2375