1 /* $OpenBSD: mux.c,v 1.103 2024/10/12 10:50:37 jsg 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 72 /* from ssh.c */ 73 extern int tty_flag; 74 extern Options options; 75 extern char *host; 76 extern struct sshbuf *command; 77 extern volatile sig_atomic_t quit_pending; 78 79 /* Context for session open confirmation callback */ 80 struct mux_session_confirm_ctx { 81 u_int want_tty; 82 u_int want_subsys; 83 u_int want_x_fwd; 84 u_int want_agent_fwd; 85 struct sshbuf *cmd; 86 char *term; 87 struct termios tio; 88 char **env; 89 u_int rid; 90 }; 91 92 /* Context for stdio fwd open confirmation callback */ 93 struct mux_stdio_confirm_ctx { 94 u_int rid; 95 }; 96 97 /* Context for global channel callback */ 98 struct mux_channel_confirm_ctx { 99 u_int cid; /* channel id */ 100 u_int rid; /* request id */ 101 int fid; /* forward id */ 102 }; 103 104 /* fd to control socket */ 105 int muxserver_sock = -1; 106 107 /* client request id */ 108 u_int muxclient_request_id = 0; 109 110 /* Multiplexing control command */ 111 u_int muxclient_command = 0; 112 113 /* Set when signalled. */ 114 static volatile sig_atomic_t muxclient_terminate = 0; 115 116 /* PID of multiplex server */ 117 static u_int muxserver_pid = 0; 118 119 static Channel *mux_listener_channel = NULL; 120 121 struct mux_master_state { 122 int hello_rcvd; 123 }; 124 125 /* mux protocol messages */ 126 #define MUX_MSG_HELLO 0x00000001 127 #define MUX_C_NEW_SESSION 0x10000002 128 #define MUX_C_ALIVE_CHECK 0x10000004 129 #define MUX_C_TERMINATE 0x10000005 130 #define MUX_C_OPEN_FWD 0x10000006 131 #define MUX_C_CLOSE_FWD 0x10000007 132 #define MUX_C_NEW_STDIO_FWD 0x10000008 133 #define MUX_C_STOP_LISTENING 0x10000009 134 #define MUX_C_PROXY 0x1000000f 135 #define MUX_S_OK 0x80000001 136 #define MUX_S_PERMISSION_DENIED 0x80000002 137 #define MUX_S_FAILURE 0x80000003 138 #define MUX_S_EXIT_MESSAGE 0x80000004 139 #define MUX_S_ALIVE 0x80000005 140 #define MUX_S_SESSION_OPENED 0x80000006 141 #define MUX_S_REMOTE_PORT 0x80000007 142 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 143 #define MUX_S_PROXY 0x8000000f 144 145 /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 146 #define MUX_FWD_LOCAL 1 147 #define MUX_FWD_REMOTE 2 148 #define MUX_FWD_DYNAMIC 3 149 150 static void mux_session_confirm(struct ssh *, int, int, void *); 151 static void mux_stdio_confirm(struct ssh *, int, int, void *); 152 153 static int mux_master_process_hello(struct ssh *, u_int, 154 Channel *, struct sshbuf *, struct sshbuf *); 155 static int mux_master_process_new_session(struct ssh *, u_int, 156 Channel *, struct sshbuf *, struct sshbuf *); 157 static int mux_master_process_alive_check(struct ssh *, u_int, 158 Channel *, struct sshbuf *, struct sshbuf *); 159 static int mux_master_process_terminate(struct ssh *, u_int, 160 Channel *, struct sshbuf *, struct sshbuf *); 161 static int mux_master_process_open_fwd(struct ssh *, u_int, 162 Channel *, struct sshbuf *, struct sshbuf *); 163 static int mux_master_process_close_fwd(struct ssh *, u_int, 164 Channel *, struct sshbuf *, struct sshbuf *); 165 static int mux_master_process_stdio_fwd(struct ssh *, u_int, 166 Channel *, struct sshbuf *, struct sshbuf *); 167 static int mux_master_process_stop_listening(struct ssh *, u_int, 168 Channel *, struct sshbuf *, struct sshbuf *); 169 static int mux_master_process_proxy(struct ssh *, u_int, 170 Channel *, struct sshbuf *, struct sshbuf *); 171 172 static const struct { 173 u_int type; 174 int (*handler)(struct ssh *, u_int, Channel *, 175 struct sshbuf *, struct sshbuf *); 176 } mux_master_handlers[] = { 177 { MUX_MSG_HELLO, mux_master_process_hello }, 178 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 179 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 180 { MUX_C_TERMINATE, mux_master_process_terminate }, 181 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 182 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 183 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 184 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 185 { MUX_C_PROXY, mux_master_process_proxy }, 186 { 0, NULL } 187 }; 188 189 /* Cleanup callback fired on closure of mux client _session_ channel */ 190 static void 191 mux_master_session_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 192 { 193 Channel *cc, *c = channel_by_id(ssh, cid); 194 195 debug3_f("entering for channel %d", cid); 196 if (c == NULL) 197 fatal_f("channel_by_id(%i) == NULL", cid); 198 if (c->ctl_chan != -1) { 199 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 200 fatal_f("channel %d missing control channel %d", 201 c->self, c->ctl_chan); 202 c->ctl_chan = -1; 203 cc->ctl_child_id = 0; 204 cc->have_ctl_child_id = 0; 205 chan_rcvd_oclose(ssh, cc); 206 } 207 channel_cancel_cleanup(ssh, c->self); 208 } 209 210 /* Cleanup callback fired on closure of mux client _control_ channel */ 211 static void 212 mux_master_control_cleanup_cb(struct ssh *ssh, int cid, int force, void *unused) 213 { 214 Channel *sc, *c = channel_by_id(ssh, cid); 215 216 debug3_f("entering for channel %d", cid); 217 if (c == NULL) 218 fatal_f("channel_by_id(%i) == NULL", cid); 219 if (c->have_ctl_child_id) { 220 if ((sc = channel_by_id(ssh, c->ctl_child_id)) == NULL) 221 fatal_f("channel %d missing session channel %u", 222 c->self, c->ctl_child_id); 223 c->ctl_child_id = 0; 224 c->have_ctl_child_id = 0; 225 sc->ctl_chan = -1; 226 if (sc->type != SSH_CHANNEL_OPEN && 227 sc->type != SSH_CHANNEL_OPENING) { 228 debug2_f("channel %d: not open", sc->self); 229 chan_mark_dead(ssh, sc); 230 } else { 231 if (sc->istate == CHAN_INPUT_OPEN) 232 chan_read_failed(ssh, sc); 233 if (sc->ostate == CHAN_OUTPUT_OPEN) 234 chan_write_failed(ssh, sc); 235 } 236 } 237 channel_cancel_cleanup(ssh, c->self); 238 } 239 240 /* Check mux client environment variables before passing them to mux master. */ 241 static int 242 env_permitted(const char *env) 243 { 244 u_int i; 245 int ret; 246 char name[1024], *cp; 247 248 if ((cp = strchr(env, '=')) == NULL || cp == env) 249 return 0; 250 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 251 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 252 error_f("name '%.100s...' too long", env); 253 return 0; 254 } 255 256 for (i = 0; i < options.num_send_env; i++) 257 if (match_pattern(name, options.send_env[i])) 258 return 1; 259 260 return 0; 261 } 262 263 /* Mux master protocol message handlers */ 264 265 static int 266 mux_master_process_hello(struct ssh *ssh, u_int rid, 267 Channel *c, struct sshbuf *m, struct sshbuf *reply) 268 { 269 u_int ver; 270 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 271 int r; 272 273 if (state == NULL) 274 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 275 if (state->hello_rcvd) { 276 error_f("HELLO received twice"); 277 return -1; 278 } 279 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 280 error_fr(r, "parse"); 281 return -1; 282 } 283 if (ver != SSHMUX_VER) { 284 error_f("unsupported multiplexing protocol version %u " 285 "(expected %u)", ver, SSHMUX_VER); 286 return -1; 287 } 288 debug2_f("channel %d client version %u", c->self, ver); 289 290 /* No extensions are presently defined */ 291 while (sshbuf_len(m) > 0) { 292 char *name = NULL; 293 size_t value_len = 0; 294 295 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 296 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 297 error_fr(r, "parse extension"); 298 return -1; 299 } 300 debug2_f("Unrecognised extension \"%s\" length %zu", 301 name, value_len); 302 free(name); 303 } 304 state->hello_rcvd = 1; 305 return 0; 306 } 307 308 /* Enqueue a "ok" response to the reply buffer */ 309 static void 310 reply_ok(struct sshbuf *reply, u_int rid) 311 { 312 int r; 313 314 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 315 (r = sshbuf_put_u32(reply, rid)) != 0) 316 fatal_fr(r, "reply"); 317 } 318 319 /* Enqueue an error response to the reply buffer */ 320 static void 321 reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 322 { 323 int r; 324 325 if ((r = sshbuf_put_u32(reply, type)) != 0 || 326 (r = sshbuf_put_u32(reply, rid)) != 0 || 327 (r = sshbuf_put_cstring(reply, msg)) != 0) 328 fatal_fr(r, "reply"); 329 } 330 331 static int 332 mux_master_process_new_session(struct ssh *ssh, u_int rid, 333 Channel *c, struct sshbuf *m, struct sshbuf *reply) 334 { 335 Channel *nc; 336 struct mux_session_confirm_ctx *cctx; 337 char *cmd, *cp; 338 u_int i, j, env_len, escape_char, window, packetmax; 339 int r, new_fd[3]; 340 341 /* Reply for SSHMUX_COMMAND_OPEN */ 342 cctx = xcalloc(1, sizeof(*cctx)); 343 cctx->term = NULL; 344 cctx->rid = rid; 345 cmd = NULL; 346 cctx->env = NULL; 347 env_len = 0; 348 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 349 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 350 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 351 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 352 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 353 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 354 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 355 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 356 malf: 357 free(cmd); 358 for (j = 0; j < env_len; j++) 359 free(cctx->env[j]); 360 free(cctx->env); 361 free(cctx->term); 362 free(cctx); 363 error_f("malformed message"); 364 return -1; 365 } 366 367 #define MUX_MAX_ENV_VARS 4096 368 while (sshbuf_len(m) > 0) { 369 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 370 goto malf; 371 if (!env_permitted(cp)) { 372 free(cp); 373 continue; 374 } 375 cctx->env = xreallocarray(cctx->env, env_len + 2, 376 sizeof(*cctx->env)); 377 cctx->env[env_len++] = cp; 378 cctx->env[env_len] = NULL; 379 if (env_len > MUX_MAX_ENV_VARS) { 380 error_f(">%d environment variables received, " 381 "ignoring additional", MUX_MAX_ENV_VARS); 382 break; 383 } 384 } 385 386 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 387 "term \"%s\", cmd \"%s\", env %u", c->self, 388 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 389 cctx->want_subsys, cctx->term, cmd, env_len); 390 391 if ((cctx->cmd = sshbuf_new()) == NULL) 392 fatal_f("sshbuf_new"); 393 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 394 fatal_fr(r, "sshbuf_put"); 395 free(cmd); 396 cmd = NULL; 397 398 /* Gather fds from client */ 399 for(i = 0; i < 3; i++) { 400 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 401 error_f("failed to receive fd %d from client", i); 402 for (j = 0; j < i; j++) 403 close(new_fd[j]); 404 for (j = 0; j < env_len; j++) 405 free(cctx->env[j]); 406 free(cctx->env); 407 free(cctx->term); 408 sshbuf_free(cctx->cmd); 409 free(cctx); 410 reply_error(reply, MUX_S_FAILURE, rid, 411 "did not receive file descriptors"); 412 return -1; 413 } 414 } 415 416 debug3_f("got fds stdin %d, stdout %d, stderr %d", 417 new_fd[0], new_fd[1], new_fd[2]); 418 419 /* XXX support multiple child sessions in future */ 420 if (c->have_ctl_child_id) { 421 debug2_f("session already open"); 422 reply_error(reply, MUX_S_FAILURE, rid, 423 "Multiple sessions not supported"); 424 cleanup: 425 close(new_fd[0]); 426 close(new_fd[1]); 427 close(new_fd[2]); 428 free(cctx->term); 429 if (env_len != 0) { 430 for (i = 0; i < env_len; i++) 431 free(cctx->env[i]); 432 free(cctx->env); 433 } 434 sshbuf_free(cctx->cmd); 435 free(cctx); 436 return 0; 437 } 438 439 if (options.control_master == SSHCTL_MASTER_ASK || 440 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 441 if (!ask_permission("Allow shared connection to %s? ", host)) { 442 debug2_f("session refused by user"); 443 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 444 "Permission denied"); 445 goto cleanup; 446 } 447 } 448 449 /* Try to pick up ttymodes from client before it goes raw */ 450 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 451 error_f("tcgetattr: %s", strerror(errno)); 452 453 window = CHAN_SES_WINDOW_DEFAULT; 454 packetmax = CHAN_SES_PACKET_DEFAULT; 455 if (cctx->want_tty) { 456 window >>= 1; 457 packetmax >>= 1; 458 } 459 460 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 461 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 462 CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO); 463 464 nc->ctl_chan = c->self; /* link session -> control channel */ 465 c->ctl_child_id = nc->self; /* link control -> session channel */ 466 c->have_ctl_child_id = 1; 467 468 if (cctx->want_tty && escape_char != 0xffffffff) { 469 channel_register_filter(ssh, nc->self, 470 client_simple_escape_filter, NULL, 471 client_filter_cleanup, 472 client_new_escape_filter_ctx((int)escape_char)); 473 } 474 475 debug2_f("channel_new: %d linked to control channel %d", 476 nc->self, nc->ctl_chan); 477 478 channel_send_open(ssh, nc->self); 479 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 480 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 481 channel_register_cleanup(ssh, nc->self, 482 mux_master_session_cleanup_cb, 1); 483 484 /* reply is deferred, sent by mux_session_confirm */ 485 return 0; 486 } 487 488 static int 489 mux_master_process_alive_check(struct ssh *ssh, u_int rid, 490 Channel *c, struct sshbuf *m, struct sshbuf *reply) 491 { 492 int r; 493 494 debug2_f("channel %d: alive check", c->self); 495 496 /* prepare reply */ 497 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 498 (r = sshbuf_put_u32(reply, rid)) != 0 || 499 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 500 fatal_fr(r, "reply"); 501 502 return 0; 503 } 504 505 static int 506 mux_master_process_terminate(struct ssh *ssh, u_int rid, 507 Channel *c, struct sshbuf *m, struct sshbuf *reply) 508 { 509 debug2_f("channel %d: terminate request", c->self); 510 511 if (options.control_master == SSHCTL_MASTER_ASK || 512 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 513 if (!ask_permission("Terminate shared connection to %s? ", 514 host)) { 515 debug2_f("termination refused by user"); 516 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 517 "Permission denied"); 518 return 0; 519 } 520 } 521 522 quit_pending = 1; 523 reply_ok(reply, rid); 524 /* XXX exit happens too soon - message never makes it to client */ 525 return 0; 526 } 527 528 static char * 529 format_forward(u_int ftype, struct Forward *fwd) 530 { 531 char *ret; 532 533 switch (ftype) { 534 case MUX_FWD_LOCAL: 535 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 536 (fwd->listen_path != NULL) ? fwd->listen_path : 537 (fwd->listen_host == NULL) ? 538 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 539 fwd->listen_host, fwd->listen_port, 540 (fwd->connect_path != NULL) ? fwd->connect_path : 541 fwd->connect_host, fwd->connect_port); 542 break; 543 case MUX_FWD_DYNAMIC: 544 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 545 (fwd->listen_host == NULL) ? 546 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 547 fwd->listen_host, fwd->listen_port); 548 break; 549 case MUX_FWD_REMOTE: 550 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 551 (fwd->listen_path != NULL) ? fwd->listen_path : 552 (fwd->listen_host == NULL) ? 553 "LOCALHOST" : fwd->listen_host, 554 fwd->listen_port, 555 (fwd->connect_path != NULL) ? fwd->connect_path : 556 fwd->connect_host, fwd->connect_port); 557 break; 558 default: 559 fatal_f("unknown forward type %u", ftype); 560 } 561 return ret; 562 } 563 564 static int 565 compare_host(const char *a, const char *b) 566 { 567 if (a == NULL && b == NULL) 568 return 1; 569 if (a == NULL || b == NULL) 570 return 0; 571 return strcmp(a, b) == 0; 572 } 573 574 static int 575 compare_forward(struct Forward *a, struct Forward *b) 576 { 577 if (!compare_host(a->listen_host, b->listen_host)) 578 return 0; 579 if (!compare_host(a->listen_path, b->listen_path)) 580 return 0; 581 if (a->listen_port != b->listen_port) 582 return 0; 583 if (!compare_host(a->connect_host, b->connect_host)) 584 return 0; 585 if (!compare_host(a->connect_path, b->connect_path)) 586 return 0; 587 if (a->connect_port != b->connect_port) 588 return 0; 589 590 return 1; 591 } 592 593 static void 594 mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 595 { 596 struct mux_channel_confirm_ctx *fctx = ctxt; 597 char *failmsg = NULL; 598 struct Forward *rfwd; 599 Channel *c; 600 struct sshbuf *out; 601 u_int port; 602 int r; 603 604 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 605 /* no channel for reply */ 606 error_f("unknown channel"); 607 return; 608 } 609 if ((out = sshbuf_new()) == NULL) 610 fatal_f("sshbuf_new"); 611 if (fctx->fid >= options.num_remote_forwards || 612 (options.remote_forwards[fctx->fid].connect_path == NULL && 613 options.remote_forwards[fctx->fid].connect_host == NULL)) { 614 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 615 goto fail; 616 } 617 rfwd = &options.remote_forwards[fctx->fid]; 618 debug_f("%s for: listen %d, connect %s:%d", 619 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 620 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 621 rfwd->connect_host, rfwd->connect_port); 622 if (type == SSH2_MSG_REQUEST_SUCCESS) { 623 if (rfwd->listen_port == 0) { 624 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 625 fatal_fr(r, "parse port"); 626 if (port > 65535) { 627 fatal("Invalid allocated port %u for " 628 "mux remote forward to %s:%d", port, 629 rfwd->connect_host, rfwd->connect_port); 630 } 631 rfwd->allocated_port = (int)port; 632 debug("Allocated port %u for mux remote forward" 633 " to %s:%d", rfwd->allocated_port, 634 rfwd->connect_host, rfwd->connect_port); 635 if ((r = sshbuf_put_u32(out, 636 MUX_S_REMOTE_PORT)) != 0 || 637 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 638 (r = sshbuf_put_u32(out, 639 rfwd->allocated_port)) != 0) 640 fatal_fr(r, "reply"); 641 channel_update_permission(ssh, rfwd->handle, 642 rfwd->allocated_port); 643 } else { 644 reply_ok(out, fctx->rid); 645 } 646 goto out; 647 } else { 648 if (rfwd->listen_port == 0) 649 channel_update_permission(ssh, rfwd->handle, -1); 650 if (rfwd->listen_path != NULL) 651 xasprintf(&failmsg, "remote port forwarding failed for " 652 "listen path %s", rfwd->listen_path); 653 else 654 xasprintf(&failmsg, "remote port forwarding failed for " 655 "listen port %d", rfwd->listen_port); 656 657 debug2_f("clearing registered forwarding for listen %d, " 658 "connect %s:%d", rfwd->listen_port, 659 rfwd->connect_path ? rfwd->connect_path : 660 rfwd->connect_host, rfwd->connect_port); 661 662 free(rfwd->listen_host); 663 free(rfwd->listen_path); 664 free(rfwd->connect_host); 665 free(rfwd->connect_path); 666 memset(rfwd, 0, sizeof(*rfwd)); 667 } 668 fail: 669 error_f("%s", failmsg); 670 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 671 free(failmsg); 672 out: 673 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 674 fatal_fr(r, "enqueue"); 675 sshbuf_free(out); 676 if (c->mux_pause <= 0) 677 fatal_f("mux_pause %d", c->mux_pause); 678 c->mux_pause = 0; /* start processing messages again */ 679 } 680 681 static int 682 mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 683 Channel *c, struct sshbuf *m, struct sshbuf *reply) 684 { 685 struct Forward fwd; 686 char *fwd_desc = NULL; 687 char *listen_addr, *connect_addr; 688 u_int ftype; 689 u_int lport, cport; 690 int r, i, ret = 0, freefwd = 1; 691 692 memset(&fwd, 0, sizeof(fwd)); 693 694 /* XXX - lport/cport check redundant */ 695 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 696 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 697 (r = sshbuf_get_u32(m, &lport)) != 0 || 698 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 699 (r = sshbuf_get_u32(m, &cport)) != 0 || 700 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 701 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 702 error_f("malformed message"); 703 ret = -1; 704 goto out; 705 } 706 if (*listen_addr == '\0') { 707 free(listen_addr); 708 listen_addr = NULL; 709 } 710 if (*connect_addr == '\0') { 711 free(connect_addr); 712 connect_addr = NULL; 713 } 714 715 memset(&fwd, 0, sizeof(fwd)); 716 fwd.listen_port = lport; 717 if (fwd.listen_port == PORT_STREAMLOCAL) 718 fwd.listen_path = listen_addr; 719 else 720 fwd.listen_host = listen_addr; 721 fwd.connect_port = cport; 722 if (fwd.connect_port == PORT_STREAMLOCAL) 723 fwd.connect_path = connect_addr; 724 else 725 fwd.connect_host = connect_addr; 726 727 debug2_f("channel %d: request %s", c->self, 728 (fwd_desc = format_forward(ftype, &fwd))); 729 730 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 731 ftype != MUX_FWD_DYNAMIC) { 732 logit_f("invalid forwarding type %u", ftype); 733 invalid: 734 free(listen_addr); 735 free(connect_addr); 736 reply_error(reply, MUX_S_FAILURE, rid, 737 "Invalid forwarding request"); 738 return 0; 739 } 740 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 741 logit_f("streamlocal and dynamic forwards " 742 "are mutually exclusive"); 743 goto invalid; 744 } 745 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 746 logit_f("invalid listen port %u", fwd.listen_port); 747 goto invalid; 748 } 749 if ((fwd.connect_port != PORT_STREAMLOCAL && 750 fwd.connect_port >= 65536) || 751 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 752 fwd.connect_port == 0)) { 753 logit_f("invalid connect port %u", 754 fwd.connect_port); 755 goto invalid; 756 } 757 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 758 fwd.connect_path == NULL) { 759 logit_f("missing connect host"); 760 goto invalid; 761 } 762 763 /* Skip forwards that have already been requested */ 764 switch (ftype) { 765 case MUX_FWD_LOCAL: 766 case MUX_FWD_DYNAMIC: 767 for (i = 0; i < options.num_local_forwards; i++) { 768 if (compare_forward(&fwd, 769 options.local_forwards + i)) { 770 exists: 771 debug2_f("found existing forwarding"); 772 reply_ok(reply, rid); 773 goto out; 774 } 775 } 776 break; 777 case MUX_FWD_REMOTE: 778 for (i = 0; i < options.num_remote_forwards; i++) { 779 if (!compare_forward(&fwd, options.remote_forwards + i)) 780 continue; 781 if (fwd.listen_port != 0) 782 goto exists; 783 debug2_f("found allocated port"); 784 if ((r = sshbuf_put_u32(reply, 785 MUX_S_REMOTE_PORT)) != 0 || 786 (r = sshbuf_put_u32(reply, rid)) != 0 || 787 (r = sshbuf_put_u32(reply, 788 options.remote_forwards[i].allocated_port)) != 0) 789 fatal_fr(r, "reply FWD_REMOTE"); 790 goto out; 791 } 792 break; 793 } 794 795 if (options.control_master == SSHCTL_MASTER_ASK || 796 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 797 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 798 debug2_f("forwarding refused by user"); 799 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 800 "Permission denied"); 801 goto out; 802 } 803 } 804 805 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 806 if (!channel_setup_local_fwd_listener(ssh, &fwd, 807 &options.fwd_opts)) { 808 fail: 809 logit_f("requested %s failed", fwd_desc); 810 reply_error(reply, MUX_S_FAILURE, rid, 811 "Port forwarding failed"); 812 goto out; 813 } 814 add_local_forward(&options, &fwd); 815 freefwd = 0; 816 } else { 817 struct mux_channel_confirm_ctx *fctx; 818 819 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 820 if (fwd.handle < 0) 821 goto fail; 822 add_remote_forward(&options, &fwd); 823 fctx = xcalloc(1, sizeof(*fctx)); 824 fctx->cid = c->self; 825 fctx->rid = rid; 826 fctx->fid = options.num_remote_forwards - 1; 827 client_register_global_confirm(mux_confirm_remote_forward, 828 fctx); 829 freefwd = 0; 830 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 831 /* delayed reply in mux_confirm_remote_forward */ 832 goto out; 833 } 834 reply_ok(reply, rid); 835 out: 836 free(fwd_desc); 837 if (freefwd) { 838 free(fwd.listen_host); 839 free(fwd.listen_path); 840 free(fwd.connect_host); 841 free(fwd.connect_path); 842 } 843 return ret; 844 } 845 846 static int 847 mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 848 Channel *c, struct sshbuf *m, struct sshbuf *reply) 849 { 850 struct Forward fwd, *found_fwd; 851 char *fwd_desc = NULL; 852 const char *error_reason = NULL; 853 char *listen_addr = NULL, *connect_addr = NULL; 854 u_int ftype; 855 int r, i, ret = 0; 856 u_int lport, cport; 857 858 memset(&fwd, 0, sizeof(fwd)); 859 860 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 861 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 862 (r = sshbuf_get_u32(m, &lport)) != 0 || 863 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 864 (r = sshbuf_get_u32(m, &cport)) != 0 || 865 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 866 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 867 error_f("malformed message"); 868 ret = -1; 869 goto out; 870 } 871 872 if (*listen_addr == '\0') { 873 free(listen_addr); 874 listen_addr = NULL; 875 } 876 if (*connect_addr == '\0') { 877 free(connect_addr); 878 connect_addr = NULL; 879 } 880 881 memset(&fwd, 0, sizeof(fwd)); 882 fwd.listen_port = lport; 883 if (fwd.listen_port == PORT_STREAMLOCAL) 884 fwd.listen_path = listen_addr; 885 else 886 fwd.listen_host = listen_addr; 887 fwd.connect_port = cport; 888 if (fwd.connect_port == PORT_STREAMLOCAL) 889 fwd.connect_path = connect_addr; 890 else 891 fwd.connect_host = connect_addr; 892 893 debug2_f("channel %d: request cancel %s", c->self, 894 (fwd_desc = format_forward(ftype, &fwd))); 895 896 /* make sure this has been requested */ 897 found_fwd = NULL; 898 switch (ftype) { 899 case MUX_FWD_LOCAL: 900 case MUX_FWD_DYNAMIC: 901 for (i = 0; i < options.num_local_forwards; i++) { 902 if (compare_forward(&fwd, 903 options.local_forwards + i)) { 904 found_fwd = options.local_forwards + i; 905 break; 906 } 907 } 908 break; 909 case MUX_FWD_REMOTE: 910 for (i = 0; i < options.num_remote_forwards; i++) { 911 if (compare_forward(&fwd, 912 options.remote_forwards + i)) { 913 found_fwd = options.remote_forwards + i; 914 break; 915 } 916 } 917 break; 918 } 919 920 if (found_fwd == NULL) 921 error_reason = "port not forwarded"; 922 else if (ftype == MUX_FWD_REMOTE) { 923 /* 924 * This shouldn't fail unless we confused the host/port 925 * between options.remote_forwards and permitted_opens. 926 * However, for dynamic allocated listen ports we need 927 * to use the actual listen port. 928 */ 929 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 930 error_reason = "port not in permitted opens"; 931 } else { /* local and dynamic forwards */ 932 /* Ditto */ 933 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 934 &options.fwd_opts) == -1) 935 error_reason = "port not found"; 936 } 937 938 if (error_reason != NULL) 939 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 940 else { 941 reply_ok(reply, rid); 942 free(found_fwd->listen_host); 943 free(found_fwd->listen_path); 944 free(found_fwd->connect_host); 945 free(found_fwd->connect_path); 946 found_fwd->listen_host = found_fwd->connect_host = NULL; 947 found_fwd->listen_path = found_fwd->connect_path = NULL; 948 found_fwd->listen_port = found_fwd->connect_port = 0; 949 } 950 out: 951 free(fwd_desc); 952 free(listen_addr); 953 free(connect_addr); 954 955 return ret; 956 } 957 958 static int 959 mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 960 Channel *c, struct sshbuf *m, struct sshbuf *reply) 961 { 962 Channel *nc; 963 char *chost = NULL; 964 u_int _cport, i, j; 965 int ok = 0, cport, r, new_fd[2]; 966 struct mux_stdio_confirm_ctx *cctx; 967 968 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 969 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 970 (r = sshbuf_get_u32(m, &_cport)) != 0) { 971 free(chost); 972 error_f("malformed message"); 973 return -1; 974 } 975 if (_cport == (u_int)PORT_STREAMLOCAL) 976 cport = PORT_STREAMLOCAL; 977 else if (_cport <= INT_MAX) 978 cport = (int)_cport; 979 else { 980 free(chost); 981 error_f("invalid port 0x%x", _cport); 982 return -1; 983 } 984 985 debug2_f("channel %d: stdio fwd to %s:%d", c->self, chost, cport); 986 987 /* Gather fds from client */ 988 for(i = 0; i < 2; i++) { 989 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 990 error_f("failed to receive fd %d from client", i); 991 for (j = 0; j < i; j++) 992 close(new_fd[j]); 993 free(chost); 994 995 /* prepare reply */ 996 reply_error(reply, MUX_S_FAILURE, rid, 997 "did not receive file descriptors"); 998 return -1; 999 } 1000 } 1001 1002 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 1003 1004 /* XXX support multiple child sessions in future */ 1005 if (c->have_ctl_child_id) { 1006 debug2_f("session already open"); 1007 reply_error(reply, MUX_S_FAILURE, rid, 1008 "Multiple sessions not supported"); 1009 cleanup: 1010 close(new_fd[0]); 1011 close(new_fd[1]); 1012 free(chost); 1013 return 0; 1014 } 1015 1016 if (options.control_master == SSHCTL_MASTER_ASK || 1017 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1018 if (cport == PORT_STREAMLOCAL) { 1019 ok = ask_permission("Allow forward to path %s", chost); 1020 } else { 1021 ok = ask_permission("Allow forward to [%s]:%d? ", 1022 chost, cport); 1023 } 1024 if (!ok) { 1025 debug2_f("stdio fwd refused by user"); 1026 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1027 "Permission denied"); 1028 goto cleanup; 1029 } 1030 } 1031 1032 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1], 1033 CHANNEL_NONBLOCK_STDIO); 1034 free(chost); 1035 1036 nc->ctl_chan = c->self; /* link session -> control channel */ 1037 c->ctl_child_id = nc->self; /* link control -> session channel */ 1038 c->have_ctl_child_id = 1; 1039 1040 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan); 1041 1042 channel_register_cleanup(ssh, nc->self, 1043 mux_master_session_cleanup_cb, 1); 1044 1045 cctx = xcalloc(1, sizeof(*cctx)); 1046 cctx->rid = rid; 1047 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1048 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1049 1050 /* reply is deferred, sent by mux_session_confirm */ 1051 return 0; 1052 } 1053 1054 /* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1055 static void 1056 mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1057 { 1058 struct mux_stdio_confirm_ctx *cctx = arg; 1059 Channel *c, *cc; 1060 struct sshbuf *reply; 1061 int r; 1062 1063 if (cctx == NULL) 1064 fatal_f("cctx == NULL"); 1065 if ((c = channel_by_id(ssh, id)) == NULL) 1066 fatal_f("no channel for id %d", id); 1067 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1068 fatal_f("channel %d lacks control channel %d", 1069 id, c->ctl_chan); 1070 if ((reply = sshbuf_new()) == NULL) 1071 fatal_f("sshbuf_new"); 1072 1073 if (!success) { 1074 debug3_f("sending failure reply"); 1075 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1076 "Session open refused by peer"); 1077 /* prepare reply */ 1078 goto done; 1079 } 1080 1081 debug3_f("sending success reply"); 1082 /* prepare reply */ 1083 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1084 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1085 (r = sshbuf_put_u32(reply, c->self)) != 0) 1086 fatal_fr(r, "reply"); 1087 1088 done: 1089 /* Send reply */ 1090 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1091 fatal_fr(r, "enqueue"); 1092 sshbuf_free(reply); 1093 1094 if (cc->mux_pause <= 0) 1095 fatal_f("mux_pause %d", cc->mux_pause); 1096 cc->mux_pause = 0; /* start processing messages again */ 1097 c->open_confirm_ctx = NULL; 1098 free(cctx); 1099 } 1100 1101 static int 1102 mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1103 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1104 { 1105 debug_f("channel %d: stop listening", c->self); 1106 1107 if (options.control_master == SSHCTL_MASTER_ASK || 1108 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1109 if (!ask_permission("Disable further multiplexing on shared " 1110 "connection to %s? ", host)) { 1111 debug2_f("stop listen refused by user"); 1112 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1113 "Permission denied"); 1114 return 0; 1115 } 1116 } 1117 1118 if (mux_listener_channel != NULL) { 1119 channel_free(ssh, mux_listener_channel); 1120 client_stop_mux(); 1121 free(options.control_path); 1122 options.control_path = NULL; 1123 mux_listener_channel = NULL; 1124 muxserver_sock = -1; 1125 } 1126 1127 reply_ok(reply, rid); 1128 return 0; 1129 } 1130 1131 static int 1132 mux_master_process_proxy(struct ssh *ssh, u_int rid, 1133 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1134 { 1135 int r; 1136 1137 debug_f("channel %d: proxy request", c->self); 1138 1139 c->mux_rcb = channel_proxy_downstream; 1140 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1141 (r = sshbuf_put_u32(reply, rid)) != 0) 1142 fatal_fr(r, "reply"); 1143 1144 return 0; 1145 } 1146 1147 /* Channel callbacks fired on read/write from mux client fd */ 1148 static int 1149 mux_master_read_cb(struct ssh *ssh, Channel *c) 1150 { 1151 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1152 struct sshbuf *in = NULL, *out = NULL; 1153 u_int type, rid, i; 1154 int r, ret = -1; 1155 1156 if ((out = sshbuf_new()) == NULL) 1157 fatal_f("sshbuf_new"); 1158 1159 /* Setup ctx and */ 1160 if (c->mux_ctx == NULL) { 1161 state = xcalloc(1, sizeof(*state)); 1162 c->mux_ctx = state; 1163 channel_register_cleanup(ssh, c->self, 1164 mux_master_control_cleanup_cb, 0); 1165 1166 /* Send hello */ 1167 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1168 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1169 fatal_fr(r, "reply"); 1170 /* no extensions */ 1171 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1172 fatal_fr(r, "enqueue"); 1173 debug3_f("channel %d: hello sent", c->self); 1174 ret = 0; 1175 goto out; 1176 } 1177 1178 /* Channel code ensures that we receive whole packets */ 1179 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1180 malf: 1181 error_f("malformed message"); 1182 goto out; 1183 } 1184 1185 if ((r = sshbuf_get_u32(in, &type)) != 0) 1186 goto malf; 1187 debug3_f("channel %d packet type 0x%08x len %zu", c->self, 1188 type, sshbuf_len(in)); 1189 1190 if (type == MUX_MSG_HELLO) 1191 rid = 0; 1192 else { 1193 if (!state->hello_rcvd) { 1194 error_f("expected MUX_MSG_HELLO(0x%08x), " 1195 "received 0x%08x", MUX_MSG_HELLO, type); 1196 goto out; 1197 } 1198 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1199 goto malf; 1200 } 1201 1202 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1203 if (type == mux_master_handlers[i].type) { 1204 ret = mux_master_handlers[i].handler(ssh, rid, 1205 c, in, out); 1206 break; 1207 } 1208 } 1209 if (mux_master_handlers[i].handler == NULL) { 1210 error_f("unsupported mux message 0x%08x", type); 1211 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1212 ret = 0; 1213 } 1214 /* Enqueue reply packet */ 1215 if (sshbuf_len(out) != 0 && 1216 (r = sshbuf_put_stringb(c->output, out)) != 0) 1217 fatal_fr(r, "enqueue"); 1218 out: 1219 sshbuf_free(in); 1220 sshbuf_free(out); 1221 return ret; 1222 } 1223 1224 void 1225 mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1226 { 1227 struct sshbuf *m; 1228 Channel *mux_chan; 1229 int r; 1230 1231 debug3_f("channel %d: exit message, exitval %d", c->self, exitval); 1232 1233 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1234 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1235 1236 /* Append exit message packet to control socket output queue */ 1237 if ((m = sshbuf_new()) == NULL) 1238 fatal_f("sshbuf_new"); 1239 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1240 (r = sshbuf_put_u32(m, c->self)) != 0 || 1241 (r = sshbuf_put_u32(m, exitval)) != 0 || 1242 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1243 fatal_fr(r, "reply"); 1244 sshbuf_free(m); 1245 } 1246 1247 void 1248 mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1249 { 1250 struct sshbuf *m; 1251 Channel *mux_chan; 1252 int r; 1253 1254 debug3_f("channel %d: TTY alloc failed", c->self); 1255 1256 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1257 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1258 1259 /* Append exit message packet to control socket output queue */ 1260 if ((m = sshbuf_new()) == NULL) 1261 fatal_f("sshbuf_new"); 1262 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1263 (r = sshbuf_put_u32(m, c->self)) != 0 || 1264 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1265 fatal_fr(r, "reply"); 1266 sshbuf_free(m); 1267 } 1268 1269 /* Prepare a mux master to listen on a Unix domain socket. */ 1270 void 1271 muxserver_listen(struct ssh *ssh) 1272 { 1273 mode_t old_umask; 1274 char *orig_control_path = options.control_path; 1275 char rbuf[16+1]; 1276 u_int i, r; 1277 int oerrno; 1278 1279 if (options.control_path == NULL || 1280 options.control_master == SSHCTL_MASTER_NO) 1281 return; 1282 1283 debug("setting up multiplex master socket"); 1284 1285 /* 1286 * Use a temporary path before listen so we can pseudo-atomically 1287 * establish the listening socket in its final location to avoid 1288 * other processes racing in between bind() and listen() and hitting 1289 * an unready socket. 1290 */ 1291 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1292 r = arc4random_uniform(26+26+10); 1293 rbuf[i] = (r < 26) ? 'a' + r : 1294 (r < 26*2) ? 'A' + r - 26 : 1295 '0' + r - 26 - 26; 1296 } 1297 rbuf[sizeof(rbuf) - 1] = '\0'; 1298 options.control_path = NULL; 1299 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1300 debug3_f("temporary control path %s", options.control_path); 1301 1302 old_umask = umask(0177); 1303 muxserver_sock = unix_listener(options.control_path, 64, 0); 1304 oerrno = errno; 1305 umask(old_umask); 1306 if (muxserver_sock < 0) { 1307 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1308 error("ControlSocket %s already exists, " 1309 "disabling multiplexing", options.control_path); 1310 disable_mux_master: 1311 if (muxserver_sock != -1) { 1312 close(muxserver_sock); 1313 muxserver_sock = -1; 1314 } 1315 free(orig_control_path); 1316 free(options.control_path); 1317 options.control_path = NULL; 1318 options.control_master = SSHCTL_MASTER_NO; 1319 return; 1320 } else { 1321 /* unix_listener() logs the error */ 1322 cleanup_exit(255); 1323 } 1324 } 1325 1326 /* Now atomically "move" the mux socket into position */ 1327 if (link(options.control_path, orig_control_path) != 0) { 1328 if (errno != EEXIST) { 1329 fatal_f("link mux listener %s => %s: %s", 1330 options.control_path, orig_control_path, 1331 strerror(errno)); 1332 } 1333 error("ControlSocket %s already exists, disabling multiplexing", 1334 orig_control_path); 1335 unlink(options.control_path); 1336 goto disable_mux_master; 1337 } 1338 unlink(options.control_path); 1339 free(options.control_path); 1340 options.control_path = orig_control_path; 1341 1342 set_nonblock(muxserver_sock); 1343 1344 mux_listener_channel = channel_new(ssh, "mux listener", 1345 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1346 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1347 0, options.control_path, 1); 1348 mux_listener_channel->mux_rcb = mux_master_read_cb; 1349 debug3_f("mux listener channel %d fd %d", 1350 mux_listener_channel->self, mux_listener_channel->sock); 1351 } 1352 1353 /* Callback on open confirmation in mux master for a mux client session. */ 1354 static void 1355 mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1356 { 1357 struct mux_session_confirm_ctx *cctx = arg; 1358 const char *display; 1359 Channel *c, *cc; 1360 int i, r; 1361 struct sshbuf *reply; 1362 1363 if (cctx == NULL) 1364 fatal_f("cctx == NULL"); 1365 if ((c = channel_by_id(ssh, id)) == NULL) 1366 fatal_f("no channel for id %d", id); 1367 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1368 fatal_f("channel %d lacks control channel %d", 1369 id, c->ctl_chan); 1370 if ((reply = sshbuf_new()) == NULL) 1371 fatal_f("sshbuf_new"); 1372 1373 if (!success) { 1374 debug3_f("sending failure reply"); 1375 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1376 "Session open refused by peer"); 1377 goto done; 1378 } 1379 1380 display = getenv("DISPLAY"); 1381 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1382 char *proto, *data; 1383 1384 /* Get reasonable local authentication information. */ 1385 if (client_x11_get_proto(ssh, display, options.xauth_location, 1386 options.forward_x11_trusted, options.forward_x11_timeout, 1387 &proto, &data) == 0) { 1388 /* Request forwarding with authentication spoofing. */ 1389 debug("Requesting X11 forwarding with authentication " 1390 "spoofing."); 1391 x11_request_forwarding_with_spoofing(ssh, id, 1392 display, proto, data, 1); 1393 /* XXX exit_on_forward_failure */ 1394 client_expect_confirm(ssh, id, "X11 forwarding", 1395 CONFIRM_WARN); 1396 } 1397 } 1398 1399 if (cctx->want_agent_fwd && options.forward_agent) { 1400 debug("Requesting authentication agent forwarding."); 1401 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1402 if ((r = sshpkt_send(ssh)) != 0) 1403 fatal_fr(r, "send"); 1404 } 1405 1406 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1407 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1408 1409 debug3_f("sending success reply"); 1410 /* prepare reply */ 1411 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1412 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1413 (r = sshbuf_put_u32(reply, c->self)) != 0) 1414 fatal_fr(r, "reply"); 1415 1416 done: 1417 /* Send reply */ 1418 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1419 fatal_fr(r, "enqueue"); 1420 sshbuf_free(reply); 1421 1422 if (cc->mux_pause <= 0) 1423 fatal_f("mux_pause %d", cc->mux_pause); 1424 cc->mux_pause = 0; /* start processing messages again */ 1425 c->open_confirm_ctx = NULL; 1426 sshbuf_free(cctx->cmd); 1427 free(cctx->term); 1428 if (cctx->env != NULL) { 1429 for (i = 0; cctx->env[i] != NULL; i++) 1430 free(cctx->env[i]); 1431 free(cctx->env); 1432 } 1433 free(cctx); 1434 } 1435 1436 /* ** Multiplexing client support */ 1437 1438 /* Exit signal handler */ 1439 static void 1440 control_client_sighandler(int signo) 1441 { 1442 muxclient_terminate = signo; 1443 } 1444 1445 /* 1446 * Relay signal handler - used to pass some signals from mux client to 1447 * mux master. 1448 */ 1449 static void 1450 control_client_sigrelay(int signo) 1451 { 1452 int save_errno = errno; 1453 1454 if (muxserver_pid > 1) 1455 kill(muxserver_pid, signo); 1456 1457 errno = save_errno; 1458 } 1459 1460 static int 1461 mux_client_read(int fd, struct sshbuf *b, size_t need, int timeout_ms) 1462 { 1463 size_t have; 1464 ssize_t len; 1465 u_char *p; 1466 int r; 1467 1468 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1469 fatal_fr(r, "reserve"); 1470 for (have = 0; have < need; ) { 1471 if (muxclient_terminate) { 1472 errno = EINTR; 1473 return -1; 1474 } 1475 len = read(fd, p + have, need - have); 1476 if (len == -1) { 1477 switch (errno) { 1478 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1479 case EWOULDBLOCK: 1480 #endif 1481 case EAGAIN: 1482 if (waitrfd(fd, &timeout_ms, 1483 &muxclient_terminate) == -1 && 1484 errno != EINTR) 1485 return -1; /* timeout */ 1486 /* FALLTHROUGH */ 1487 case EINTR: 1488 continue; 1489 default: 1490 return -1; 1491 } 1492 } 1493 if (len == 0) { 1494 errno = EPIPE; 1495 return -1; 1496 } 1497 have += (size_t)len; 1498 } 1499 return 0; 1500 } 1501 1502 static int 1503 mux_client_write_packet(int fd, struct sshbuf *m) 1504 { 1505 struct sshbuf *queue; 1506 u_int have, need; 1507 int r, oerrno, len; 1508 const u_char *ptr; 1509 struct pollfd pfd; 1510 1511 pfd.fd = fd; 1512 pfd.events = POLLOUT; 1513 if ((queue = sshbuf_new()) == NULL) 1514 fatal_f("sshbuf_new"); 1515 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1516 fatal_fr(r, "enqueue"); 1517 1518 need = sshbuf_len(queue); 1519 ptr = sshbuf_ptr(queue); 1520 1521 for (have = 0; have < need; ) { 1522 if (muxclient_terminate) { 1523 sshbuf_free(queue); 1524 errno = EINTR; 1525 return -1; 1526 } 1527 len = write(fd, ptr + have, need - have); 1528 if (len == -1) { 1529 switch (errno) { 1530 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1531 case EWOULDBLOCK: 1532 #endif 1533 case EAGAIN: 1534 (void)poll(&pfd, 1, -1); 1535 /* FALLTHROUGH */ 1536 case EINTR: 1537 continue; 1538 default: 1539 oerrno = errno; 1540 sshbuf_free(queue); 1541 errno = oerrno; 1542 return -1; 1543 } 1544 } 1545 if (len == 0) { 1546 sshbuf_free(queue); 1547 errno = EPIPE; 1548 return -1; 1549 } 1550 have += (u_int)len; 1551 } 1552 sshbuf_free(queue); 1553 return 0; 1554 } 1555 1556 static int 1557 mux_client_read_packet_timeout(int fd, struct sshbuf *m, int timeout_ms) 1558 { 1559 struct sshbuf *queue; 1560 size_t need, have; 1561 const u_char *ptr; 1562 int r, oerrno; 1563 1564 if ((queue = sshbuf_new()) == NULL) 1565 fatal_f("sshbuf_new"); 1566 if (mux_client_read(fd, queue, 4, timeout_ms) != 0) { 1567 if ((oerrno = errno) == EPIPE) 1568 debug3_f("read header failed: %s", 1569 strerror(errno)); 1570 sshbuf_free(queue); 1571 errno = oerrno; 1572 return -1; 1573 } 1574 need = PEEK_U32(sshbuf_ptr(queue)); 1575 if (mux_client_read(fd, queue, need, timeout_ms) != 0) { 1576 oerrno = errno; 1577 debug3_f("read body failed: %s", strerror(errno)); 1578 sshbuf_free(queue); 1579 errno = oerrno; 1580 return -1; 1581 } 1582 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1583 (r = sshbuf_put(m, ptr, have)) != 0) 1584 fatal_fr(r, "dequeue"); 1585 sshbuf_free(queue); 1586 return 0; 1587 } 1588 1589 static int 1590 mux_client_read_packet(int fd, struct sshbuf *m) 1591 { 1592 return mux_client_read_packet_timeout(fd, m, -1); 1593 } 1594 1595 static int 1596 mux_client_hello_exchange(int fd, int timeout_ms) 1597 { 1598 struct sshbuf *m; 1599 u_int type, ver; 1600 int r, ret = -1; 1601 1602 if ((m = sshbuf_new()) == NULL) 1603 fatal_f("sshbuf_new"); 1604 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1605 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1606 fatal_fr(r, "assemble hello"); 1607 /* no extensions */ 1608 1609 if (mux_client_write_packet(fd, m) != 0) { 1610 debug_f("write packet: %s", strerror(errno)); 1611 goto out; 1612 } 1613 1614 sshbuf_reset(m); 1615 1616 /* Read their HELLO */ 1617 if (mux_client_read_packet_timeout(fd, m, timeout_ms) != 0) { 1618 debug_f("read packet failed"); 1619 goto out; 1620 } 1621 1622 if ((r = sshbuf_get_u32(m, &type)) != 0) 1623 fatal_fr(r, "parse type"); 1624 if (type != MUX_MSG_HELLO) { 1625 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1626 goto out; 1627 } 1628 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1629 fatal_fr(r, "parse version"); 1630 if (ver != SSHMUX_VER) { 1631 error("Unsupported multiplexing protocol version %d " 1632 "(expected %d)", ver, SSHMUX_VER); 1633 goto out; 1634 } 1635 debug2_f("master version %u", ver); 1636 /* No extensions are presently defined */ 1637 while (sshbuf_len(m) > 0) { 1638 char *name = NULL; 1639 1640 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1641 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1642 error_fr(r, "parse extension"); 1643 goto out; 1644 } 1645 debug2("Unrecognised master extension \"%s\"", name); 1646 free(name); 1647 } 1648 /* success */ 1649 ret = 0; 1650 out: 1651 sshbuf_free(m); 1652 return ret; 1653 } 1654 1655 static u_int 1656 mux_client_request_alive(int fd) 1657 { 1658 struct sshbuf *m; 1659 char *e; 1660 u_int pid, type, rid; 1661 int r; 1662 1663 debug3_f("entering"); 1664 1665 if ((m = sshbuf_new()) == NULL) 1666 fatal_f("sshbuf_new"); 1667 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1668 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1669 fatal_fr(r, "assemble"); 1670 1671 if (mux_client_write_packet(fd, m) != 0) 1672 fatal_f("write packet: %s", strerror(errno)); 1673 1674 sshbuf_reset(m); 1675 1676 /* Read their reply */ 1677 if (mux_client_read_packet(fd, m) != 0) { 1678 sshbuf_free(m); 1679 return 0; 1680 } 1681 1682 if ((r = sshbuf_get_u32(m, &type)) != 0) 1683 fatal_fr(r, "parse type"); 1684 if (type != MUX_S_ALIVE) { 1685 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1686 fatal_fr(r, "parse error message"); 1687 fatal_f("master returned error: %s", e); 1688 } 1689 1690 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1691 fatal_fr(r, "parse remote ID"); 1692 if (rid != muxclient_request_id) 1693 fatal_f("out of sequence reply: my id %u theirs %u", 1694 muxclient_request_id, rid); 1695 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1696 fatal_fr(r, "parse PID"); 1697 sshbuf_free(m); 1698 1699 debug3_f("done pid = %u", pid); 1700 1701 muxclient_request_id++; 1702 1703 return pid; 1704 } 1705 1706 static void 1707 mux_client_request_terminate(int fd) 1708 { 1709 struct sshbuf *m; 1710 char *e; 1711 u_int type, rid; 1712 int r; 1713 1714 debug3_f("entering"); 1715 1716 if ((m = sshbuf_new()) == NULL) 1717 fatal_f("sshbuf_new"); 1718 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1719 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1720 fatal_fr(r, "request"); 1721 1722 if (mux_client_write_packet(fd, m) != 0) 1723 fatal_f("write packet: %s", strerror(errno)); 1724 1725 sshbuf_reset(m); 1726 1727 /* Read their reply */ 1728 if (mux_client_read_packet(fd, m) != 0) { 1729 /* Remote end exited already */ 1730 if (errno == EPIPE) { 1731 sshbuf_free(m); 1732 return; 1733 } 1734 fatal_f("read from master failed: %s", strerror(errno)); 1735 } 1736 1737 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1738 (r = sshbuf_get_u32(m, &rid)) != 0) 1739 fatal_fr(r, "parse"); 1740 if (rid != muxclient_request_id) 1741 fatal_f("out of sequence reply: my id %u theirs %u", 1742 muxclient_request_id, rid); 1743 switch (type) { 1744 case MUX_S_OK: 1745 break; 1746 case MUX_S_PERMISSION_DENIED: 1747 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1748 fatal_fr(r, "parse error message"); 1749 fatal("Master refused termination request: %s", e); 1750 case MUX_S_FAILURE: 1751 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1752 fatal_fr(r, "parse error message"); 1753 fatal_f("termination request failed: %s", e); 1754 default: 1755 fatal_f("unexpected response from master 0x%08x", type); 1756 } 1757 sshbuf_free(m); 1758 muxclient_request_id++; 1759 } 1760 1761 static int 1762 mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1763 { 1764 struct sshbuf *m; 1765 char *e, *fwd_desc; 1766 const char *lhost, *chost; 1767 u_int type, rid; 1768 int r; 1769 1770 fwd_desc = format_forward(ftype, fwd); 1771 debug("Requesting %s %s", 1772 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1773 free(fwd_desc); 1774 1775 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1776 if (fwd->listen_path != NULL) 1777 lhost = fwd->listen_path; 1778 else if (fwd->listen_host == NULL) 1779 lhost = ""; 1780 else if (*fwd->listen_host == '\0') 1781 lhost = "*"; 1782 else 1783 lhost = fwd->listen_host; 1784 1785 if (fwd->connect_path != NULL) 1786 chost = fwd->connect_path; 1787 else if (fwd->connect_host == NULL) 1788 chost = ""; 1789 else 1790 chost = fwd->connect_host; 1791 1792 if ((m = sshbuf_new()) == NULL) 1793 fatal_f("sshbuf_new"); 1794 if ((r = sshbuf_put_u32(m, type)) != 0 || 1795 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1796 (r = sshbuf_put_u32(m, ftype)) != 0 || 1797 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1798 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1799 (r = sshbuf_put_cstring(m, chost)) != 0 || 1800 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1801 fatal_fr(r, "request"); 1802 1803 if (mux_client_write_packet(fd, m) != 0) 1804 fatal_f("write packet: %s", strerror(errno)); 1805 1806 sshbuf_reset(m); 1807 1808 /* Read their reply */ 1809 if (mux_client_read_packet(fd, m) != 0) { 1810 sshbuf_free(m); 1811 return -1; 1812 } 1813 1814 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1815 (r = sshbuf_get_u32(m, &rid)) != 0) 1816 fatal_fr(r, "parse"); 1817 if (rid != muxclient_request_id) 1818 fatal_f("out of sequence reply: my id %u theirs %u", 1819 muxclient_request_id, rid); 1820 1821 switch (type) { 1822 case MUX_S_OK: 1823 break; 1824 case MUX_S_REMOTE_PORT: 1825 if (cancel_flag) 1826 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1827 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1828 fatal_fr(r, "parse port"); 1829 verbose("Allocated port %u for remote forward to %s:%d", 1830 fwd->allocated_port, 1831 fwd->connect_host ? fwd->connect_host : "", 1832 fwd->connect_port); 1833 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1834 fprintf(stdout, "%i\n", fwd->allocated_port); 1835 break; 1836 case MUX_S_PERMISSION_DENIED: 1837 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1838 fatal_fr(r, "parse error message"); 1839 sshbuf_free(m); 1840 error("Master refused forwarding request: %s", e); 1841 return -1; 1842 case MUX_S_FAILURE: 1843 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1844 fatal_fr(r, "parse error message"); 1845 sshbuf_free(m); 1846 error_f("forwarding request failed: %s", e); 1847 return -1; 1848 default: 1849 fatal_f("unexpected response from master 0x%08x", type); 1850 } 1851 sshbuf_free(m); 1852 1853 muxclient_request_id++; 1854 return 0; 1855 } 1856 1857 static int 1858 mux_client_forwards(int fd, int cancel_flag) 1859 { 1860 int i, ret = 0; 1861 1862 debug3_f("%s forwardings: %d local, %d remote", 1863 cancel_flag ? "cancel" : "request", 1864 options.num_local_forwards, options.num_remote_forwards); 1865 1866 /* XXX ExitOnForwardingFailure */ 1867 for (i = 0; i < options.num_local_forwards; i++) { 1868 if (mux_client_forward(fd, cancel_flag, 1869 options.local_forwards[i].connect_port == 0 ? 1870 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1871 options.local_forwards + i) != 0) 1872 ret = -1; 1873 } 1874 for (i = 0; i < options.num_remote_forwards; i++) { 1875 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1876 options.remote_forwards + i) != 0) 1877 ret = -1; 1878 } 1879 return ret; 1880 } 1881 1882 static int 1883 mux_client_request_session(int fd) 1884 { 1885 struct sshbuf *m; 1886 char *e; 1887 const char *term = NULL; 1888 u_int i, echar, rid, sid, esid, exitval, type, exitval_seen; 1889 extern char **environ; 1890 int r, rawmode = 0; 1891 1892 debug3_f("entering"); 1893 1894 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1895 error_f("master alive request failed"); 1896 return -1; 1897 } 1898 1899 ssh_signal(SIGPIPE, SIG_IGN); 1900 1901 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 1902 fatal_f("stdfd_devnull failed"); 1903 1904 if ((term = lookup_env_in_list("TERM", options.setenv, 1905 options.num_setenv)) == NULL || *term == '\0') 1906 term = getenv("TERM"); 1907 1908 echar = 0xffffffff; 1909 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1910 echar = (u_int)options.escape_char; 1911 1912 if ((m = sshbuf_new()) == NULL) 1913 fatal_f("sshbuf_new"); 1914 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1915 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1916 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1917 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1918 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1919 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1920 (r = sshbuf_put_u32(m, options.session_type == SESSION_TYPE_SUBSYSTEM)) != 0 || 1921 (r = sshbuf_put_u32(m, echar)) != 0 || 1922 (r = sshbuf_put_cstring(m, term == NULL ? "" : term)) != 0 || 1923 (r = sshbuf_put_stringb(m, command)) != 0) 1924 fatal_fr(r, "request"); 1925 1926 /* Pass environment */ 1927 if (options.num_send_env > 0 && environ != NULL) { 1928 for (i = 0; environ[i] != NULL; i++) { 1929 if (!env_permitted(environ[i])) 1930 continue; 1931 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1932 fatal_fr(r, "request sendenv"); 1933 } 1934 } 1935 for (i = 0; i < options.num_setenv; i++) { 1936 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1937 fatal_fr(r, "request setenv"); 1938 } 1939 1940 if (mux_client_write_packet(fd, m) != 0) 1941 fatal_f("write packet: %s", strerror(errno)); 1942 1943 /* Send the stdio file descriptors */ 1944 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1945 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1946 mm_send_fd(fd, STDERR_FILENO) == -1) 1947 fatal_f("send fds failed"); 1948 1949 debug3_f("session request sent"); 1950 1951 /* Read their reply */ 1952 sshbuf_reset(m); 1953 if (mux_client_read_packet(fd, m) != 0) { 1954 error_f("read from master failed: %s", strerror(errno)); 1955 sshbuf_free(m); 1956 return -1; 1957 } 1958 1959 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1960 (r = sshbuf_get_u32(m, &rid)) != 0) 1961 fatal_fr(r, "parse"); 1962 if (rid != muxclient_request_id) 1963 fatal_f("out of sequence reply: my id %u theirs %u", 1964 muxclient_request_id, rid); 1965 1966 switch (type) { 1967 case MUX_S_SESSION_OPENED: 1968 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1969 fatal_fr(r, "parse session ID"); 1970 debug_f("master session id: %u", sid); 1971 break; 1972 case MUX_S_PERMISSION_DENIED: 1973 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1974 fatal_fr(r, "parse error message"); 1975 error("Master refused session request: %s", e); 1976 sshbuf_free(m); 1977 return -1; 1978 case MUX_S_FAILURE: 1979 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1980 fatal_fr(r, "parse error message"); 1981 error_f("session request failed: %s", e); 1982 sshbuf_free(m); 1983 return -1; 1984 default: 1985 sshbuf_free(m); 1986 error_f("unexpected response from master 0x%08x", type); 1987 return -1; 1988 } 1989 muxclient_request_id++; 1990 1991 if (pledge("stdio proc tty", NULL) == -1) 1992 fatal_f("pledge(): %s", strerror(errno)); 1993 platform_pledge_mux(); 1994 1995 ssh_signal(SIGHUP, control_client_sighandler); 1996 ssh_signal(SIGINT, control_client_sighandler); 1997 ssh_signal(SIGTERM, control_client_sighandler); 1998 ssh_signal(SIGWINCH, control_client_sigrelay); 1999 2000 if (options.fork_after_authentication) 2001 daemon(1, 1); 2002 else { 2003 rawmode = tty_flag; 2004 if (tty_flag) { 2005 enter_raw_mode( 2006 options.request_tty == REQUEST_TTY_FORCE); 2007 } 2008 } 2009 2010 /* 2011 * Stick around until the controlee closes the client_fd. 2012 * Before it does, it is expected to write an exit message. 2013 * This process must read the value and wait for the closure of 2014 * the client_fd; if this one closes early, the multiplex master will 2015 * terminate early too (possibly losing data). 2016 */ 2017 for (exitval = 255, exitval_seen = 0;;) { 2018 sshbuf_reset(m); 2019 if (mux_client_read_packet(fd, m) != 0) 2020 break; 2021 if ((r = sshbuf_get_u32(m, &type)) != 0) 2022 fatal_fr(r, "parse type"); 2023 switch (type) { 2024 case MUX_S_TTY_ALLOC_FAIL: 2025 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2026 fatal_fr(r, "parse session ID"); 2027 if (esid != sid) 2028 fatal_f("tty alloc fail on unknown session: " 2029 "my id %u theirs %u", sid, esid); 2030 leave_raw_mode(options.request_tty == 2031 REQUEST_TTY_FORCE); 2032 rawmode = 0; 2033 continue; 2034 case MUX_S_EXIT_MESSAGE: 2035 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2036 fatal_fr(r, "parse session ID"); 2037 if (esid != sid) 2038 fatal_f("exit on unknown session: " 2039 "my id %u theirs %u", sid, esid); 2040 if (exitval_seen) 2041 fatal_f("exitval sent twice"); 2042 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2043 fatal_fr(r, "parse exitval"); 2044 exitval_seen = 1; 2045 continue; 2046 default: 2047 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2048 fatal_fr(r, "parse error message"); 2049 fatal_f("master returned error: %s", e); 2050 } 2051 } 2052 2053 close(fd); 2054 if (rawmode) 2055 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2056 2057 if (muxclient_terminate) { 2058 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2059 exitval = 255; 2060 } else if (!exitval_seen) { 2061 debug2("Control master terminated unexpectedly"); 2062 exitval = 255; 2063 } else 2064 debug2("Received exit status from master %d", exitval); 2065 2066 if (tty_flag && options.log_level >= SYSLOG_LEVEL_INFO) 2067 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2068 2069 exit(exitval); 2070 } 2071 2072 static int 2073 mux_client_proxy(int fd) 2074 { 2075 struct sshbuf *m; 2076 char *e; 2077 u_int type, rid; 2078 int r; 2079 2080 if ((m = sshbuf_new()) == NULL) 2081 fatal_f("sshbuf_new"); 2082 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2083 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2084 fatal_fr(r, "request"); 2085 if (mux_client_write_packet(fd, m) != 0) 2086 fatal_f("write packet: %s", strerror(errno)); 2087 2088 sshbuf_reset(m); 2089 2090 /* Read their reply */ 2091 if (mux_client_read_packet(fd, m) != 0) { 2092 sshbuf_free(m); 2093 return 0; 2094 } 2095 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2096 (r = sshbuf_get_u32(m, &rid)) != 0) 2097 fatal_fr(r, "parse"); 2098 if (rid != muxclient_request_id) 2099 fatal_f("out of sequence reply: my id %u theirs %u", 2100 muxclient_request_id, rid); 2101 if (type != MUX_S_PROXY) { 2102 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2103 fatal_fr(r, "parse error message"); 2104 fatal_f("master returned error: %s", e); 2105 } 2106 sshbuf_free(m); 2107 2108 debug3_f("done"); 2109 muxclient_request_id++; 2110 return 0; 2111 } 2112 2113 static int 2114 mux_client_request_stdio_fwd(int fd) 2115 { 2116 struct sshbuf *m; 2117 char *e; 2118 u_int type, rid, sid; 2119 int r; 2120 2121 debug3_f("entering"); 2122 2123 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2124 error_f("master alive request failed"); 2125 return -1; 2126 } 2127 2128 ssh_signal(SIGPIPE, SIG_IGN); 2129 2130 if (options.stdin_null && stdfd_devnull(1, 0, 0) == -1) 2131 fatal_f("stdfd_devnull failed"); 2132 2133 if ((m = sshbuf_new()) == NULL) 2134 fatal_f("sshbuf_new"); 2135 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2136 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2137 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2138 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2139 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2140 fatal_fr(r, "request"); 2141 2142 if (mux_client_write_packet(fd, m) != 0) 2143 fatal_f("write packet: %s", strerror(errno)); 2144 2145 /* Send the stdio file descriptors */ 2146 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2147 mm_send_fd(fd, STDOUT_FILENO) == -1) 2148 fatal_f("send fds failed"); 2149 2150 if (pledge("stdio proc tty", NULL) == -1) 2151 fatal_f("pledge(): %s", strerror(errno)); 2152 platform_pledge_mux(); 2153 2154 debug3_f("stdio forward request sent"); 2155 2156 /* Read their reply */ 2157 sshbuf_reset(m); 2158 2159 if (mux_client_read_packet(fd, m) != 0) { 2160 error_f("read from master failed: %s", strerror(errno)); 2161 sshbuf_free(m); 2162 return -1; 2163 } 2164 2165 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2166 (r = sshbuf_get_u32(m, &rid)) != 0) 2167 fatal_fr(r, "parse"); 2168 if (rid != muxclient_request_id) 2169 fatal_f("out of sequence reply: my id %u theirs %u", 2170 muxclient_request_id, rid); 2171 switch (type) { 2172 case MUX_S_SESSION_OPENED: 2173 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2174 fatal_fr(r, "parse session ID"); 2175 debug_f("master session id: %u", sid); 2176 break; 2177 case MUX_S_PERMISSION_DENIED: 2178 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2179 fatal_fr(r, "parse error message"); 2180 sshbuf_free(m); 2181 fatal("Master refused stdio forwarding request: %s", e); 2182 case MUX_S_FAILURE: 2183 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2184 fatal_fr(r, "parse error message"); 2185 sshbuf_free(m); 2186 fatal("Stdio forwarding request failed: %s", e); 2187 default: 2188 sshbuf_free(m); 2189 error_f("unexpected response from master 0x%08x", type); 2190 return -1; 2191 } 2192 muxclient_request_id++; 2193 2194 ssh_signal(SIGHUP, control_client_sighandler); 2195 ssh_signal(SIGINT, control_client_sighandler); 2196 ssh_signal(SIGTERM, control_client_sighandler); 2197 ssh_signal(SIGWINCH, control_client_sigrelay); 2198 2199 /* 2200 * Stick around until the controlee closes the client_fd. 2201 */ 2202 sshbuf_reset(m); 2203 if (mux_client_read_packet(fd, m) != 0) { 2204 if (errno == EPIPE || 2205 (errno == EINTR && muxclient_terminate != 0)) 2206 return 0; 2207 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2208 } 2209 fatal_f("master returned unexpected message %u", type); 2210 } 2211 2212 static void 2213 mux_client_request_stop_listening(int fd) 2214 { 2215 struct sshbuf *m; 2216 char *e; 2217 u_int type, rid; 2218 int r; 2219 2220 debug3_f("entering"); 2221 2222 if ((m = sshbuf_new()) == NULL) 2223 fatal_f("sshbuf_new"); 2224 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2225 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2226 fatal_fr(r, "request"); 2227 2228 if (mux_client_write_packet(fd, m) != 0) 2229 fatal_f("write packet: %s", strerror(errno)); 2230 2231 sshbuf_reset(m); 2232 2233 /* Read their reply */ 2234 if (mux_client_read_packet(fd, m) != 0) 2235 fatal_f("read from master failed: %s", strerror(errno)); 2236 2237 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2238 (r = sshbuf_get_u32(m, &rid)) != 0) 2239 fatal_fr(r, "parse"); 2240 if (rid != muxclient_request_id) 2241 fatal_f("out of sequence reply: my id %u theirs %u", 2242 muxclient_request_id, rid); 2243 2244 switch (type) { 2245 case MUX_S_OK: 2246 break; 2247 case MUX_S_PERMISSION_DENIED: 2248 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2249 fatal_fr(r, "parse error message"); 2250 fatal("Master refused stop listening request: %s", e); 2251 case MUX_S_FAILURE: 2252 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2253 fatal_fr(r, "parse error message"); 2254 fatal_f("stop listening request failed: %s", e); 2255 default: 2256 fatal_f("unexpected response from master 0x%08x", type); 2257 } 2258 sshbuf_free(m); 2259 muxclient_request_id++; 2260 } 2261 2262 /* Multiplex client main loop. */ 2263 int 2264 muxclient(const char *path) 2265 { 2266 struct sockaddr_un addr; 2267 int sock, timeout = options.connection_timeout, timeout_ms = -1; 2268 u_int pid; 2269 2270 if (muxclient_command == 0) { 2271 if (options.stdio_forward_host != NULL) 2272 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2273 else 2274 muxclient_command = SSHMUX_COMMAND_OPEN; 2275 } 2276 2277 switch (options.control_master) { 2278 case SSHCTL_MASTER_AUTO: 2279 case SSHCTL_MASTER_AUTO_ASK: 2280 debug("auto-mux: Trying existing master at '%s'", path); 2281 /* FALLTHROUGH */ 2282 case SSHCTL_MASTER_NO: 2283 break; 2284 default: 2285 return -1; 2286 } 2287 2288 memset(&addr, '\0', sizeof(addr)); 2289 addr.sun_family = AF_UNIX; 2290 2291 if (strlcpy(addr.sun_path, path, 2292 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2293 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2294 (unsigned int)sizeof(addr.sun_path)); 2295 2296 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2297 fatal_f("socket(): %s", strerror(errno)); 2298 2299 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2300 switch (muxclient_command) { 2301 case SSHMUX_COMMAND_OPEN: 2302 case SSHMUX_COMMAND_STDIO_FWD: 2303 break; 2304 default: 2305 fatal("Control socket connect(%.100s): %s", path, 2306 strerror(errno)); 2307 } 2308 if (errno == ECONNREFUSED && 2309 options.control_master != SSHCTL_MASTER_NO) { 2310 debug("Stale control socket %.100s, unlinking", path); 2311 unlink(path); 2312 } else if (errno == ENOENT) { 2313 debug("Control socket \"%.100s\" does not exist", path); 2314 } else { 2315 error("Control socket connect(%.100s): %s", path, 2316 strerror(errno)); 2317 } 2318 close(sock); 2319 return -1; 2320 } 2321 set_nonblock(sock); 2322 2323 /* Timeout on initial connection only. */ 2324 if (timeout > 0 && timeout < INT_MAX / 1000) 2325 timeout_ms = timeout * 1000; 2326 2327 if (mux_client_hello_exchange(sock, timeout_ms) != 0) { 2328 error_f("master hello exchange failed"); 2329 close(sock); 2330 return -1; 2331 } 2332 2333 switch (muxclient_command) { 2334 case SSHMUX_COMMAND_ALIVE_CHECK: 2335 if ((pid = mux_client_request_alive(sock)) == 0) 2336 fatal_f("master alive check failed"); 2337 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2338 exit(0); 2339 case SSHMUX_COMMAND_TERMINATE: 2340 mux_client_request_terminate(sock); 2341 if (options.log_level != SYSLOG_LEVEL_QUIET) 2342 fprintf(stderr, "Exit request sent.\r\n"); 2343 exit(0); 2344 case SSHMUX_COMMAND_FORWARD: 2345 if (mux_client_forwards(sock, 0) != 0) 2346 fatal_f("master forward request failed"); 2347 exit(0); 2348 case SSHMUX_COMMAND_OPEN: 2349 if (mux_client_forwards(sock, 0) != 0) { 2350 error_f("master forward request failed"); 2351 return -1; 2352 } 2353 mux_client_request_session(sock); 2354 return -1; 2355 case SSHMUX_COMMAND_STDIO_FWD: 2356 mux_client_request_stdio_fwd(sock); 2357 exit(0); 2358 case SSHMUX_COMMAND_STOP: 2359 mux_client_request_stop_listening(sock); 2360 if (options.log_level != SYSLOG_LEVEL_QUIET) 2361 fprintf(stderr, "Stop listening request sent.\r\n"); 2362 exit(0); 2363 case SSHMUX_COMMAND_CANCEL_FWD: 2364 if (mux_client_forwards(sock, 1) != 0) 2365 error_f("master cancel forward request failed"); 2366 exit(0); 2367 case SSHMUX_COMMAND_PROXY: 2368 mux_client_proxy(sock); 2369 return (sock); 2370 default: 2371 fatal("unrecognised muxclient_command %d", muxclient_command); 2372 } 2373 } 2374