1/* $OpenBSD: mux.c,v 1.77 2018/09/26 07:32:44 djm Exp $ */ 2/* 3 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18/* ssh session multiplexing support */ 19 20#include "includes.h" 21__RCSID("$FreeBSD$"); 22 23#include <sys/types.h> 24#include <sys/stat.h> 25#include <sys/socket.h> 26#include <sys/un.h> 27 28#include <errno.h> 29#include <fcntl.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 */ 73extern int tty_flag; 74extern Options options; 75extern int stdin_null_flag; 76extern char *host; 77extern int subsystem_flag; 78extern struct sshbuf *command; 79extern volatile sig_atomic_t quit_pending; 80 81/* Context for session open confirmation callback */ 82struct mux_session_confirm_ctx { 83 u_int want_tty; 84 u_int want_subsys; 85 u_int want_x_fwd; 86 u_int want_agent_fwd; 87 struct sshbuf *cmd; 88 char *term; 89 struct termios tio; 90 char **env; 91 u_int rid; 92}; 93 94/* Context for stdio fwd open confirmation callback */ 95struct mux_stdio_confirm_ctx { 96 u_int rid; 97}; 98 99/* Context for global channel callback */ 100struct mux_channel_confirm_ctx { 101 u_int cid; /* channel id */ 102 u_int rid; /* request id */ 103 int fid; /* forward id */ 104}; 105 106/* fd to control socket */ 107int muxserver_sock = -1; 108 109/* client request id */ 110u_int muxclient_request_id = 0; 111 112/* Multiplexing control command */ 113u_int muxclient_command = 0; 114 115/* Set when signalled. */ 116static volatile sig_atomic_t muxclient_terminate = 0; 117 118/* PID of multiplex server */ 119static u_int muxserver_pid = 0; 120 121static Channel *mux_listener_channel = NULL; 122 123struct mux_master_state { 124 int hello_rcvd; 125}; 126 127/* mux protocol messages */ 128#define MUX_MSG_HELLO 0x00000001 129#define MUX_C_NEW_SESSION 0x10000002 130#define MUX_C_ALIVE_CHECK 0x10000004 131#define MUX_C_TERMINATE 0x10000005 132#define MUX_C_OPEN_FWD 0x10000006 133#define MUX_C_CLOSE_FWD 0x10000007 134#define MUX_C_NEW_STDIO_FWD 0x10000008 135#define MUX_C_STOP_LISTENING 0x10000009 136#define MUX_C_PROXY 0x1000000f 137#define MUX_S_OK 0x80000001 138#define MUX_S_PERMISSION_DENIED 0x80000002 139#define MUX_S_FAILURE 0x80000003 140#define MUX_S_EXIT_MESSAGE 0x80000004 141#define MUX_S_ALIVE 0x80000005 142#define MUX_S_SESSION_OPENED 0x80000006 143#define MUX_S_REMOTE_PORT 0x80000007 144#define MUX_S_TTY_ALLOC_FAIL 0x80000008 145#define MUX_S_PROXY 0x8000000f 146 147/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 148#define MUX_FWD_LOCAL 1 149#define MUX_FWD_REMOTE 2 150#define MUX_FWD_DYNAMIC 3 151 152static void mux_session_confirm(struct ssh *, int, int, void *); 153static void mux_stdio_confirm(struct ssh *, int, int, void *); 154 155static int mux_master_process_hello(struct ssh *, u_int, 156 Channel *, struct sshbuf *, struct sshbuf *); 157static int mux_master_process_new_session(struct ssh *, u_int, 158 Channel *, struct sshbuf *, struct sshbuf *); 159static int mux_master_process_alive_check(struct ssh *, u_int, 160 Channel *, struct sshbuf *, struct sshbuf *); 161static int mux_master_process_terminate(struct ssh *, u_int, 162 Channel *, struct sshbuf *, struct sshbuf *); 163static int mux_master_process_open_fwd(struct ssh *, u_int, 164 Channel *, struct sshbuf *, struct sshbuf *); 165static int mux_master_process_close_fwd(struct ssh *, u_int, 166 Channel *, struct sshbuf *, struct sshbuf *); 167static int mux_master_process_stdio_fwd(struct ssh *, u_int, 168 Channel *, struct sshbuf *, struct sshbuf *); 169static int mux_master_process_stop_listening(struct ssh *, u_int, 170 Channel *, struct sshbuf *, struct sshbuf *); 171static int mux_master_process_proxy(struct ssh *, u_int, 172 Channel *, struct sshbuf *, struct sshbuf *); 173 174static const struct { 175 u_int type; 176 int (*handler)(struct ssh *, u_int, Channel *, 177 struct sshbuf *, struct sshbuf *); 178} mux_master_handlers[] = { 179 { MUX_MSG_HELLO, mux_master_process_hello }, 180 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 181 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 182 { MUX_C_TERMINATE, mux_master_process_terminate }, 183 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 184 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 185 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 186 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 187 { MUX_C_PROXY, mux_master_process_proxy }, 188 { 0, NULL } 189}; 190 191/* Cleanup callback fired on closure of mux slave _session_ channel */ 192/* ARGSUSED */ 193static void 194mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused) 195{ 196 Channel *cc, *c = channel_by_id(ssh, cid); 197 198 debug3("%s: entering for channel %d", __func__, cid); 199 if (c == NULL) 200 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 201 if (c->ctl_chan != -1) { 202 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 203 fatal("%s: channel %d missing control channel %d", 204 __func__, c->self, c->ctl_chan); 205 c->ctl_chan = -1; 206 cc->remote_id = 0; 207 cc->have_remote_id = 0; 208 chan_rcvd_oclose(ssh, cc); 209 } 210 channel_cancel_cleanup(ssh, c->self); 211} 212 213/* Cleanup callback fired on closure of mux slave _control_ channel */ 214/* ARGSUSED */ 215static void 216mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused) 217{ 218 Channel *sc, *c = channel_by_id(ssh, cid); 219 220 debug3("%s: entering for channel %d", __func__, cid); 221 if (c == NULL) 222 fatal("%s: channel_by_id(%i) == NULL", __func__, cid); 223 if (c->have_remote_id) { 224 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 225 fatal("%s: channel %d missing session channel %u", 226 __func__, c->self, c->remote_id); 227 c->remote_id = 0; 228 c->have_remote_id = 0; 229 sc->ctl_chan = -1; 230 if (sc->type != SSH_CHANNEL_OPEN && 231 sc->type != SSH_CHANNEL_OPENING) { 232 debug2("%s: channel %d: not open", __func__, sc->self); 233 chan_mark_dead(ssh, sc); 234 } else { 235 if (sc->istate == CHAN_INPUT_OPEN) 236 chan_read_failed(ssh, sc); 237 if (sc->ostate == CHAN_OUTPUT_OPEN) 238 chan_write_failed(ssh, sc); 239 } 240 } 241 channel_cancel_cleanup(ssh, c->self); 242} 243 244/* Check mux client environment variables before passing them to mux master. */ 245static int 246env_permitted(char *env) 247{ 248 int i, ret; 249 char name[1024], *cp; 250 251 if ((cp = strchr(env, '=')) == NULL || cp == env) 252 return 0; 253 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 254 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 255 error("%s: name '%.100s...' too long", __func__, env); 256 return 0; 257 } 258 259 for (i = 0; i < options.num_send_env; i++) 260 if (match_pattern(name, options.send_env[i])) 261 return 1; 262 263 return 0; 264} 265 266/* Mux master protocol message handlers */ 267 268static int 269mux_master_process_hello(struct ssh *ssh, u_int rid, 270 Channel *c, struct sshbuf *m, struct sshbuf *reply) 271{ 272 u_int ver; 273 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 274 int r; 275 276 if (state == NULL) 277 fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); 278 if (state->hello_rcvd) { 279 error("%s: HELLO received twice", __func__); 280 return -1; 281 } 282 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 283 error("%s: malformed message: %s", __func__, ssh_err(r)); 284 return -1; 285 } 286 if (ver != SSHMUX_VER) { 287 error("%s: unsupported multiplexing protocol version %u " 288 "(expected %u)", __func__, ver, SSHMUX_VER); 289 return -1; 290 } 291 debug2("%s: channel %d slave version %u", __func__, c->self, ver); 292 293 /* No extensions are presently defined */ 294 while (sshbuf_len(m) > 0) { 295 char *name = NULL; 296 size_t value_len = 0; 297 298 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 299 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 300 error("%s: malformed extension: %s", 301 __func__, ssh_err(r)); 302 return -1; 303 } 304 debug2("%s: Unrecognised extension \"%s\" length %zu", 305 __func__, name, value_len); 306 free(name); 307 } 308 state->hello_rcvd = 1; 309 return 0; 310} 311 312/* Enqueue a "ok" response to the reply buffer */ 313static void 314reply_ok(struct sshbuf *reply, u_int rid) 315{ 316 int r; 317 318 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 319 (r = sshbuf_put_u32(reply, rid)) != 0) 320 fatal("%s: reply: %s", __func__, ssh_err(r)); 321} 322 323/* Enqueue an error response to the reply buffer */ 324static void 325reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 326{ 327 int r; 328 329 if ((r = sshbuf_put_u32(reply, type)) != 0 || 330 (r = sshbuf_put_u32(reply, rid)) != 0 || 331 (r = sshbuf_put_cstring(reply, msg)) != 0) 332 fatal("%s: reply: %s", __func__, ssh_err(r)); 333} 334 335static int 336mux_master_process_new_session(struct ssh *ssh, u_int rid, 337 Channel *c, struct sshbuf *m, struct sshbuf *reply) 338{ 339 Channel *nc; 340 struct mux_session_confirm_ctx *cctx; 341 char *cmd, *cp; 342 u_int i, j, env_len, escape_char, window, packetmax; 343 int r, new_fd[3]; 344 345 /* Reply for SSHMUX_COMMAND_OPEN */ 346 cctx = xcalloc(1, sizeof(*cctx)); 347 cctx->term = NULL; 348 cctx->rid = rid; 349 cmd = NULL; 350 cctx->env = NULL; 351 env_len = 0; 352 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 353 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 354 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 355 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 356 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 357 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 358 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 359 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 360 malf: 361 free(cmd); 362 for (j = 0; j < env_len; j++) 363 free(cctx->env[j]); 364 free(cctx->env); 365 free(cctx->term); 366 free(cctx); 367 error("%s: malformed message", __func__); 368 return -1; 369 } 370 371#define MUX_MAX_ENV_VARS 4096 372 while (sshbuf_len(m) > 0) { 373 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 374 goto malf; 375 if (!env_permitted(cp)) { 376 free(cp); 377 continue; 378 } 379 cctx->env = xreallocarray(cctx->env, env_len + 2, 380 sizeof(*cctx->env)); 381 cctx->env[env_len++] = cp; 382 cctx->env[env_len] = NULL; 383 if (env_len > MUX_MAX_ENV_VARS) { 384 error("%s: >%d environment variables received, " 385 "ignoring additional", __func__, MUX_MAX_ENV_VARS); 386 break; 387 } 388 } 389 390 debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " 391 "term \"%s\", cmd \"%s\", env %u", __func__, c->self, 392 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 393 cctx->want_subsys, cctx->term, cmd, env_len); 394 395 if ((cctx->cmd = sshbuf_new()) == NULL) 396 fatal("%s: sshbuf_new", __func__); 397 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 398 fatal("%s: sshbuf_put: %s", __func__, ssh_err(r)); 399 free(cmd); 400 cmd = NULL; 401 402 /* Gather fds from client */ 403 for(i = 0; i < 3; i++) { 404 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 405 error("%s: failed to receive fd %d from slave", 406 __func__, i); 407 for (j = 0; j < i; j++) 408 close(new_fd[j]); 409 for (j = 0; j < env_len; j++) 410 free(cctx->env[j]); 411 free(cctx->env); 412 free(cctx->term); 413 sshbuf_free(cctx->cmd); 414 free(cctx); 415 reply_error(reply, MUX_S_FAILURE, rid, 416 "did not receive file descriptors"); 417 return -1; 418 } 419 } 420 421 debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, 422 new_fd[0], new_fd[1], new_fd[2]); 423 424 /* XXX support multiple child sessions in future */ 425 if (c->have_remote_id) { 426 debug2("%s: session already open", __func__); 427 reply_error(reply, MUX_S_FAILURE, rid, 428 "Multiple sessions not supported"); 429 cleanup: 430 close(new_fd[0]); 431 close(new_fd[1]); 432 close(new_fd[2]); 433 free(cctx->term); 434 if (env_len != 0) { 435 for (i = 0; i < env_len; i++) 436 free(cctx->env[i]); 437 free(cctx->env); 438 } 439 sshbuf_free(cctx->cmd); 440 free(cctx); 441 return 0; 442 } 443 444 if (options.control_master == SSHCTL_MASTER_ASK || 445 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 446 if (!ask_permission("Allow shared connection to %s? ", host)) { 447 debug2("%s: session refused by user", __func__); 448 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 449 "Permission denied"); 450 goto cleanup; 451 } 452 } 453 454 /* Try to pick up ttymodes from client before it goes raw */ 455 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 456 error("%s: tcgetattr: %s", __func__, strerror(errno)); 457 458 /* enable nonblocking unless tty */ 459 if (!isatty(new_fd[0])) 460 set_nonblock(new_fd[0]); 461 if (!isatty(new_fd[1])) 462 set_nonblock(new_fd[1]); 463 if (!isatty(new_fd[2])) 464 set_nonblock(new_fd[2]); 465 466 window = CHAN_SES_WINDOW_DEFAULT; 467 packetmax = CHAN_SES_PACKET_DEFAULT; 468 if (cctx->want_tty) { 469 window >>= 1; 470 packetmax >>= 1; 471 } 472 473 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 474 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 475 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 476 477 nc->ctl_chan = c->self; /* link session -> control channel */ 478 c->remote_id = nc->self; /* link control -> session channel */ 479 c->have_remote_id = 1; 480 481 if (cctx->want_tty && escape_char != 0xffffffff) { 482 channel_register_filter(ssh, nc->self, 483 client_simple_escape_filter, NULL, 484 client_filter_cleanup, 485 client_new_escape_filter_ctx((int)escape_char)); 486 } 487 488 debug2("%s: channel_new: %d linked to control channel %d", 489 __func__, nc->self, nc->ctl_chan); 490 491 channel_send_open(ssh, nc->self); 492 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 493 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 494 channel_register_cleanup(ssh, nc->self, 495 mux_master_session_cleanup_cb, 1); 496 497 /* reply is deferred, sent by mux_session_confirm */ 498 return 0; 499} 500 501static int 502mux_master_process_alive_check(struct ssh *ssh, u_int rid, 503 Channel *c, struct sshbuf *m, struct sshbuf *reply) 504{ 505 int r; 506 507 debug2("%s: channel %d: alive check", __func__, c->self); 508 509 /* prepare reply */ 510 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 511 (r = sshbuf_put_u32(reply, rid)) != 0 || 512 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 513 fatal("%s: reply: %s", __func__, ssh_err(r)); 514 515 return 0; 516} 517 518static int 519mux_master_process_terminate(struct ssh *ssh, u_int rid, 520 Channel *c, struct sshbuf *m, struct sshbuf *reply) 521{ 522 debug2("%s: channel %d: terminate request", __func__, c->self); 523 524 if (options.control_master == SSHCTL_MASTER_ASK || 525 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 526 if (!ask_permission("Terminate shared connection to %s? ", 527 host)) { 528 debug2("%s: termination refused by user", __func__); 529 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 530 "Permission denied"); 531 return 0; 532 } 533 } 534 535 quit_pending = 1; 536 reply_ok(reply, rid); 537 /* XXX exit happens too soon - message never makes it to client */ 538 return 0; 539} 540 541static char * 542format_forward(u_int ftype, struct Forward *fwd) 543{ 544 char *ret; 545 546 switch (ftype) { 547 case MUX_FWD_LOCAL: 548 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 549 (fwd->listen_path != NULL) ? fwd->listen_path : 550 (fwd->listen_host == NULL) ? 551 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 552 fwd->listen_host, fwd->listen_port, 553 (fwd->connect_path != NULL) ? fwd->connect_path : 554 fwd->connect_host, fwd->connect_port); 555 break; 556 case MUX_FWD_DYNAMIC: 557 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 558 (fwd->listen_host == NULL) ? 559 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 560 fwd->listen_host, fwd->listen_port); 561 break; 562 case MUX_FWD_REMOTE: 563 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 564 (fwd->listen_path != NULL) ? fwd->listen_path : 565 (fwd->listen_host == NULL) ? 566 "LOCALHOST" : fwd->listen_host, 567 fwd->listen_port, 568 (fwd->connect_path != NULL) ? fwd->connect_path : 569 fwd->connect_host, fwd->connect_port); 570 break; 571 default: 572 fatal("%s: unknown forward type %u", __func__, ftype); 573 } 574 return ret; 575} 576 577static int 578compare_host(const char *a, const char *b) 579{ 580 if (a == NULL && b == NULL) 581 return 1; 582 if (a == NULL || b == NULL) 583 return 0; 584 return strcmp(a, b) == 0; 585} 586 587static int 588compare_forward(struct Forward *a, struct Forward *b) 589{ 590 if (!compare_host(a->listen_host, b->listen_host)) 591 return 0; 592 if (!compare_host(a->listen_path, b->listen_path)) 593 return 0; 594 if (a->listen_port != b->listen_port) 595 return 0; 596 if (!compare_host(a->connect_host, b->connect_host)) 597 return 0; 598 if (!compare_host(a->connect_path, b->connect_path)) 599 return 0; 600 if (a->connect_port != b->connect_port) 601 return 0; 602 603 return 1; 604} 605 606static void 607mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 608{ 609 struct mux_channel_confirm_ctx *fctx = ctxt; 610 char *failmsg = NULL; 611 struct Forward *rfwd; 612 Channel *c; 613 struct sshbuf *out; 614 int r; 615 616 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 617 /* no channel for reply */ 618 error("%s: unknown channel", __func__); 619 return; 620 } 621 if ((out = sshbuf_new()) == NULL) 622 fatal("%s: sshbuf_new", __func__); 623 if (fctx->fid >= options.num_remote_forwards || 624 (options.remote_forwards[fctx->fid].connect_path == NULL && 625 options.remote_forwards[fctx->fid].connect_host == NULL)) { 626 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 627 goto fail; 628 } 629 rfwd = &options.remote_forwards[fctx->fid]; 630 debug("%s: %s for: listen %d, connect %s:%d", __func__, 631 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 632 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 633 rfwd->connect_host, rfwd->connect_port); 634 if (type == SSH2_MSG_REQUEST_SUCCESS) { 635 if (rfwd->listen_port == 0) { 636 rfwd->allocated_port = packet_get_int(); 637 debug("Allocated port %u for mux remote forward" 638 " to %s:%d", rfwd->allocated_port, 639 rfwd->connect_host, rfwd->connect_port); 640 if ((r = sshbuf_put_u32(out, 641 MUX_S_REMOTE_PORT)) != 0 || 642 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 643 (r = sshbuf_put_u32(out, 644 rfwd->allocated_port)) != 0) 645 fatal("%s: reply: %s", __func__, ssh_err(r)); 646 channel_update_permission(ssh, rfwd->handle, 647 rfwd->allocated_port); 648 } else { 649 reply_ok(out, fctx->rid); 650 } 651 goto out; 652 } else { 653 if (rfwd->listen_port == 0) 654 channel_update_permission(ssh, rfwd->handle, -1); 655 if (rfwd->listen_path != NULL) 656 xasprintf(&failmsg, "remote port forwarding failed for " 657 "listen path %s", rfwd->listen_path); 658 else 659 xasprintf(&failmsg, "remote port forwarding failed for " 660 "listen port %d", rfwd->listen_port); 661 662 debug2("%s: clearing registered forwarding for listen %d, " 663 "connect %s:%d", __func__, rfwd->listen_port, 664 rfwd->connect_path ? rfwd->connect_path : 665 rfwd->connect_host, rfwd->connect_port); 666 667 free(rfwd->listen_host); 668 free(rfwd->listen_path); 669 free(rfwd->connect_host); 670 free(rfwd->connect_path); 671 memset(rfwd, 0, sizeof(*rfwd)); 672 } 673 fail: 674 error("%s: %s", __func__, failmsg); 675 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 676 free(failmsg); 677 out: 678 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 679 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 680 sshbuf_free(out); 681 if (c->mux_pause <= 0) 682 fatal("%s: mux_pause %d", __func__, c->mux_pause); 683 c->mux_pause = 0; /* start processing messages again */ 684} 685 686static int 687mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 688 Channel *c, struct sshbuf *m, struct sshbuf *reply) 689{ 690 struct Forward fwd; 691 char *fwd_desc = NULL; 692 char *listen_addr, *connect_addr; 693 u_int ftype; 694 u_int lport, cport; 695 int r, i, ret = 0, freefwd = 1; 696 697 memset(&fwd, 0, sizeof(fwd)); 698 699 /* XXX - lport/cport check redundant */ 700 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 701 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 702 (r = sshbuf_get_u32(m, &lport)) != 0 || 703 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 704 (r = sshbuf_get_u32(m, &cport)) != 0 || 705 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 706 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 707 error("%s: malformed message", __func__); 708 ret = -1; 709 goto out; 710 } 711 if (*listen_addr == '\0') { 712 free(listen_addr); 713 listen_addr = NULL; 714 } 715 if (*connect_addr == '\0') { 716 free(connect_addr); 717 connect_addr = NULL; 718 } 719 720 memset(&fwd, 0, sizeof(fwd)); 721 fwd.listen_port = lport; 722 if (fwd.listen_port == PORT_STREAMLOCAL) 723 fwd.listen_path = listen_addr; 724 else 725 fwd.listen_host = listen_addr; 726 fwd.connect_port = cport; 727 if (fwd.connect_port == PORT_STREAMLOCAL) 728 fwd.connect_path = connect_addr; 729 else 730 fwd.connect_host = connect_addr; 731 732 debug2("%s: channel %d: request %s", __func__, c->self, 733 (fwd_desc = format_forward(ftype, &fwd))); 734 735 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 736 ftype != MUX_FWD_DYNAMIC) { 737 logit("%s: invalid forwarding type %u", __func__, ftype); 738 invalid: 739 free(listen_addr); 740 free(connect_addr); 741 reply_error(reply, MUX_S_FAILURE, rid, 742 "Invalid forwarding request"); 743 return 0; 744 } 745 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 746 logit("%s: streamlocal and dynamic forwards " 747 "are mutually exclusive", __func__); 748 goto invalid; 749 } 750 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 751 logit("%s: invalid listen port %u", __func__, 752 fwd.listen_port); 753 goto invalid; 754 } 755 if ((fwd.connect_port != PORT_STREAMLOCAL && 756 fwd.connect_port >= 65536) || 757 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 758 fwd.connect_port == 0)) { 759 logit("%s: invalid connect port %u", __func__, 760 fwd.connect_port); 761 goto invalid; 762 } 763 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 764 fwd.connect_path == NULL) { 765 logit("%s: missing connect host", __func__); 766 goto invalid; 767 } 768 769 /* Skip forwards that have already been requested */ 770 switch (ftype) { 771 case MUX_FWD_LOCAL: 772 case MUX_FWD_DYNAMIC: 773 for (i = 0; i < options.num_local_forwards; i++) { 774 if (compare_forward(&fwd, 775 options.local_forwards + i)) { 776 exists: 777 debug2("%s: found existing forwarding", 778 __func__); 779 reply_ok(reply, rid); 780 goto out; 781 } 782 } 783 break; 784 case MUX_FWD_REMOTE: 785 for (i = 0; i < options.num_remote_forwards; i++) { 786 if (!compare_forward(&fwd, options.remote_forwards + i)) 787 continue; 788 if (fwd.listen_port != 0) 789 goto exists; 790 debug2("%s: found allocated port", __func__); 791 if ((r = sshbuf_put_u32(reply, 792 MUX_S_REMOTE_PORT)) != 0 || 793 (r = sshbuf_put_u32(reply, rid)) != 0 || 794 (r = sshbuf_put_u32(reply, 795 options.remote_forwards[i].allocated_port)) != 0) 796 fatal("%s: reply: %s", __func__, ssh_err(r)); 797 goto out; 798 } 799 break; 800 } 801 802 if (options.control_master == SSHCTL_MASTER_ASK || 803 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 804 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 805 debug2("%s: forwarding refused by user", __func__); 806 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 807 "Permission denied"); 808 goto out; 809 } 810 } 811 812 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 813 if (!channel_setup_local_fwd_listener(ssh, &fwd, 814 &options.fwd_opts)) { 815 fail: 816 logit("%s: requested %s failed", __func__, fwd_desc); 817 reply_error(reply, MUX_S_FAILURE, rid, 818 "Port forwarding failed"); 819 goto out; 820 } 821 add_local_forward(&options, &fwd); 822 freefwd = 0; 823 } else { 824 struct mux_channel_confirm_ctx *fctx; 825 826 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 827 if (fwd.handle < 0) 828 goto fail; 829 add_remote_forward(&options, &fwd); 830 fctx = xcalloc(1, sizeof(*fctx)); 831 fctx->cid = c->self; 832 fctx->rid = rid; 833 fctx->fid = options.num_remote_forwards - 1; 834 client_register_global_confirm(mux_confirm_remote_forward, 835 fctx); 836 freefwd = 0; 837 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 838 /* delayed reply in mux_confirm_remote_forward */ 839 goto out; 840 } 841 reply_ok(reply, rid); 842 out: 843 free(fwd_desc); 844 if (freefwd) { 845 free(fwd.listen_host); 846 free(fwd.listen_path); 847 free(fwd.connect_host); 848 free(fwd.connect_path); 849 } 850 return ret; 851} 852 853static int 854mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 855 Channel *c, struct sshbuf *m, struct sshbuf *reply) 856{ 857 struct Forward fwd, *found_fwd; 858 char *fwd_desc = NULL; 859 const char *error_reason = NULL; 860 char *listen_addr = NULL, *connect_addr = NULL; 861 u_int ftype; 862 int r, i, ret = 0; 863 u_int lport, cport; 864 865 memset(&fwd, 0, sizeof(fwd)); 866 867 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 868 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 869 (r = sshbuf_get_u32(m, &lport)) != 0 || 870 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 871 (r = sshbuf_get_u32(m, &cport)) != 0 || 872 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 873 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 874 error("%s: malformed message", __func__); 875 ret = -1; 876 goto out; 877 } 878 879 if (*listen_addr == '\0') { 880 free(listen_addr); 881 listen_addr = NULL; 882 } 883 if (*connect_addr == '\0') { 884 free(connect_addr); 885 connect_addr = NULL; 886 } 887 888 memset(&fwd, 0, sizeof(fwd)); 889 fwd.listen_port = lport; 890 if (fwd.listen_port == PORT_STREAMLOCAL) 891 fwd.listen_path = listen_addr; 892 else 893 fwd.listen_host = listen_addr; 894 fwd.connect_port = cport; 895 if (fwd.connect_port == PORT_STREAMLOCAL) 896 fwd.connect_path = connect_addr; 897 else 898 fwd.connect_host = connect_addr; 899 900 debug2("%s: channel %d: request cancel %s", __func__, c->self, 901 (fwd_desc = format_forward(ftype, &fwd))); 902 903 /* make sure this has been requested */ 904 found_fwd = NULL; 905 switch (ftype) { 906 case MUX_FWD_LOCAL: 907 case MUX_FWD_DYNAMIC: 908 for (i = 0; i < options.num_local_forwards; i++) { 909 if (compare_forward(&fwd, 910 options.local_forwards + i)) { 911 found_fwd = options.local_forwards + i; 912 break; 913 } 914 } 915 break; 916 case MUX_FWD_REMOTE: 917 for (i = 0; i < options.num_remote_forwards; i++) { 918 if (compare_forward(&fwd, 919 options.remote_forwards + i)) { 920 found_fwd = options.remote_forwards + i; 921 break; 922 } 923 } 924 break; 925 } 926 927 if (found_fwd == NULL) 928 error_reason = "port not forwarded"; 929 else if (ftype == MUX_FWD_REMOTE) { 930 /* 931 * This shouldn't fail unless we confused the host/port 932 * between options.remote_forwards and permitted_opens. 933 * However, for dynamic allocated listen ports we need 934 * to use the actual listen port. 935 */ 936 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 937 error_reason = "port not in permitted opens"; 938 } else { /* local and dynamic forwards */ 939 /* Ditto */ 940 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 941 &options.fwd_opts) == -1) 942 error_reason = "port not found"; 943 } 944 945 if (error_reason != NULL) 946 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 947 else { 948 reply_ok(reply, rid); 949 free(found_fwd->listen_host); 950 free(found_fwd->listen_path); 951 free(found_fwd->connect_host); 952 free(found_fwd->connect_path); 953 found_fwd->listen_host = found_fwd->connect_host = NULL; 954 found_fwd->listen_path = found_fwd->connect_path = NULL; 955 found_fwd->listen_port = found_fwd->connect_port = 0; 956 } 957 out: 958 free(fwd_desc); 959 free(listen_addr); 960 free(connect_addr); 961 962 return ret; 963} 964 965static int 966mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 967 Channel *c, struct sshbuf *m, struct sshbuf *reply) 968{ 969 Channel *nc; 970 char *chost = NULL; 971 u_int cport, i, j; 972 int r, new_fd[2]; 973 struct mux_stdio_confirm_ctx *cctx; 974 975 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 976 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 977 (r = sshbuf_get_u32(m, &cport)) != 0) { 978 free(chost); 979 error("%s: malformed message", __func__); 980 return -1; 981 } 982 983 debug2("%s: channel %d: request stdio fwd to %s:%u", 984 __func__, c->self, chost, cport); 985 986 /* Gather fds from client */ 987 for(i = 0; i < 2; i++) { 988 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 989 error("%s: failed to receive fd %d from slave", 990 __func__, 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("%s: got fds stdin %d, stdout %d", __func__, 1003 new_fd[0], new_fd[1]); 1004 1005 /* XXX support multiple child sessions in future */ 1006 if (c->have_remote_id) { 1007 debug2("%s: session already open", __func__); 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 (!ask_permission("Allow forward to %s:%u? ", 1020 chost, cport)) { 1021 debug2("%s: stdio fwd refused by user", __func__); 1022 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1023 "Permission denied"); 1024 goto cleanup; 1025 } 1026 } 1027 1028 /* enable nonblocking unless tty */ 1029 if (!isatty(new_fd[0])) 1030 set_nonblock(new_fd[0]); 1031 if (!isatty(new_fd[1])) 1032 set_nonblock(new_fd[1]); 1033 1034 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]); 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("%s: channel_new: %d linked to control channel %d", 1042 __func__, nc->self, nc->ctl_chan); 1043 1044 channel_register_cleanup(ssh, nc->self, 1045 mux_master_session_cleanup_cb, 1); 1046 1047 cctx = xcalloc(1, sizeof(*cctx)); 1048 cctx->rid = rid; 1049 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1050 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1051 1052 /* reply is deferred, sent by mux_session_confirm */ 1053 return 0; 1054} 1055 1056/* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1057static void 1058mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1059{ 1060 struct mux_stdio_confirm_ctx *cctx = arg; 1061 Channel *c, *cc; 1062 struct sshbuf *reply; 1063 int r; 1064 1065 if (cctx == NULL) 1066 fatal("%s: cctx == NULL", __func__); 1067 if ((c = channel_by_id(ssh, id)) == NULL) 1068 fatal("%s: no channel for id %d", __func__, id); 1069 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1070 fatal("%s: channel %d lacks control channel %d", __func__, 1071 id, c->ctl_chan); 1072 if ((reply = sshbuf_new()) == NULL) 1073 fatal("%s: sshbuf_new", __func__); 1074 1075 if (!success) { 1076 debug3("%s: sending failure reply", __func__); 1077 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1078 "Session open refused by peer"); 1079 /* prepare reply */ 1080 goto done; 1081 } 1082 1083 debug3("%s: sending success reply", __func__); 1084 /* prepare reply */ 1085 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1086 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1087 (r = sshbuf_put_u32(reply, c->self)) != 0) 1088 fatal("%s: reply: %s", __func__, ssh_err(r)); 1089 1090 done: 1091 /* Send reply */ 1092 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1093 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 1094 sshbuf_free(reply); 1095 1096 if (cc->mux_pause <= 0) 1097 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1098 cc->mux_pause = 0; /* start processing messages again */ 1099 c->open_confirm_ctx = NULL; 1100 free(cctx); 1101} 1102 1103static int 1104mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1105 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1106{ 1107 debug("%s: channel %d: stop listening", __func__, c->self); 1108 1109 if (options.control_master == SSHCTL_MASTER_ASK || 1110 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1111 if (!ask_permission("Disable further multiplexing on shared " 1112 "connection to %s? ", host)) { 1113 debug2("%s: stop listen refused by user", __func__); 1114 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1115 "Permission denied"); 1116 return 0; 1117 } 1118 } 1119 1120 if (mux_listener_channel != NULL) { 1121 channel_free(ssh, mux_listener_channel); 1122 client_stop_mux(); 1123 free(options.control_path); 1124 options.control_path = NULL; 1125 mux_listener_channel = NULL; 1126 muxserver_sock = -1; 1127 } 1128 1129 reply_ok(reply, rid); 1130 return 0; 1131} 1132 1133static int 1134mux_master_process_proxy(struct ssh *ssh, u_int rid, 1135 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1136{ 1137 int r; 1138 1139 debug("%s: channel %d: proxy request", __func__, c->self); 1140 1141 c->mux_rcb = channel_proxy_downstream; 1142 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1143 (r = sshbuf_put_u32(reply, rid)) != 0) 1144 fatal("%s: reply: %s", __func__, ssh_err(r)); 1145 1146 return 0; 1147} 1148 1149/* Channel callbacks fired on read/write from mux slave fd */ 1150static int 1151mux_master_read_cb(struct ssh *ssh, Channel *c) 1152{ 1153 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1154 struct sshbuf *in = NULL, *out = NULL; 1155 u_int type, rid, i; 1156 int r, ret = -1; 1157 1158 if ((out = sshbuf_new()) == NULL) 1159 fatal("%s: sshbuf_new", __func__); 1160 1161 /* Setup ctx and */ 1162 if (c->mux_ctx == NULL) { 1163 state = xcalloc(1, sizeof(*state)); 1164 c->mux_ctx = state; 1165 channel_register_cleanup(ssh, c->self, 1166 mux_master_control_cleanup_cb, 0); 1167 1168 /* Send hello */ 1169 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1170 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1171 fatal("%s: reply: %s", __func__, ssh_err(r)); 1172 /* no extensions */ 1173 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1174 fatal("%s: sshbuf_put_stringb: %s", 1175 __func__, ssh_err(r)); 1176 debug3("%s: channel %d: hello sent", __func__, c->self); 1177 ret = 0; 1178 goto out; 1179 } 1180 1181 /* Channel code ensures that we receive whole packets */ 1182 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1183 malf: 1184 error("%s: malformed message", __func__); 1185 goto out; 1186 } 1187 1188 if ((r = sshbuf_get_u32(in, &type)) != 0) 1189 goto malf; 1190 debug3("%s: channel %d packet type 0x%08x len %zu", 1191 __func__, c->self, type, sshbuf_len(in)); 1192 1193 if (type == MUX_MSG_HELLO) 1194 rid = 0; 1195 else { 1196 if (!state->hello_rcvd) { 1197 error("%s: expected MUX_MSG_HELLO(0x%08x), " 1198 "received 0x%08x", __func__, MUX_MSG_HELLO, type); 1199 goto out; 1200 } 1201 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1202 goto malf; 1203 } 1204 1205 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1206 if (type == mux_master_handlers[i].type) { 1207 ret = mux_master_handlers[i].handler(ssh, rid, 1208 c, in, out); 1209 break; 1210 } 1211 } 1212 if (mux_master_handlers[i].handler == NULL) { 1213 error("%s: unsupported mux message 0x%08x", __func__, type); 1214 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1215 ret = 0; 1216 } 1217 /* Enqueue reply packet */ 1218 if (sshbuf_len(out) != 0) { 1219 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1220 fatal("%s: sshbuf_put_stringb: %s", 1221 __func__, ssh_err(r)); 1222 } 1223 out: 1224 sshbuf_free(in); 1225 sshbuf_free(out); 1226 return ret; 1227} 1228 1229void 1230mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1231{ 1232 struct sshbuf *m; 1233 Channel *mux_chan; 1234 int r; 1235 1236 debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, 1237 exitval); 1238 1239 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1240 fatal("%s: channel %d missing mux channel %d", 1241 __func__, c->self, c->ctl_chan); 1242 1243 /* Append exit message packet to control socket output queue */ 1244 if ((m = sshbuf_new()) == NULL) 1245 fatal("%s: sshbuf_new", __func__); 1246 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1247 (r = sshbuf_put_u32(m, c->self)) != 0 || 1248 (r = sshbuf_put_u32(m, exitval)) != 0 || 1249 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1250 fatal("%s: reply: %s", __func__, ssh_err(r)); 1251 sshbuf_free(m); 1252} 1253 1254void 1255mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1256{ 1257 struct sshbuf *m; 1258 Channel *mux_chan; 1259 int r; 1260 1261 debug3("%s: channel %d: TTY alloc failed", __func__, c->self); 1262 1263 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1264 fatal("%s: channel %d missing mux channel %d", 1265 __func__, c->self, c->ctl_chan); 1266 1267 /* Append exit message packet to control socket output queue */ 1268 if ((m = sshbuf_new()) == NULL) 1269 fatal("%s: sshbuf_new", __func__); 1270 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1271 (r = sshbuf_put_u32(m, c->self)) != 0 || 1272 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1273 fatal("%s: reply: %s", __func__, ssh_err(r)); 1274 sshbuf_free(m); 1275} 1276 1277/* Prepare a mux master to listen on a Unix domain socket. */ 1278void 1279muxserver_listen(struct ssh *ssh) 1280{ 1281 mode_t old_umask; 1282 char *orig_control_path = options.control_path; 1283 char rbuf[16+1]; 1284 u_int i, r; 1285 int oerrno; 1286 1287 if (options.control_path == NULL || 1288 options.control_master == SSHCTL_MASTER_NO) 1289 return; 1290 1291 debug("setting up multiplex master socket"); 1292 1293 /* 1294 * Use a temporary path before listen so we can pseudo-atomically 1295 * establish the listening socket in its final location to avoid 1296 * other processes racing in between bind() and listen() and hitting 1297 * an unready socket. 1298 */ 1299 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1300 r = arc4random_uniform(26+26+10); 1301 rbuf[i] = (r < 26) ? 'a' + r : 1302 (r < 26*2) ? 'A' + r - 26 : 1303 '0' + r - 26 - 26; 1304 } 1305 rbuf[sizeof(rbuf) - 1] = '\0'; 1306 options.control_path = NULL; 1307 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1308 debug3("%s: temporary control path %s", __func__, options.control_path); 1309 1310 old_umask = umask(0177); 1311 muxserver_sock = unix_listener(options.control_path, 64, 0); 1312 oerrno = errno; 1313 umask(old_umask); 1314 if (muxserver_sock < 0) { 1315 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1316 error("ControlSocket %s already exists, " 1317 "disabling multiplexing", options.control_path); 1318 disable_mux_master: 1319 if (muxserver_sock != -1) { 1320 close(muxserver_sock); 1321 muxserver_sock = -1; 1322 } 1323 free(orig_control_path); 1324 free(options.control_path); 1325 options.control_path = NULL; 1326 options.control_master = SSHCTL_MASTER_NO; 1327 return; 1328 } else { 1329 /* unix_listener() logs the error */ 1330 cleanup_exit(255); 1331 } 1332 } 1333 1334 /* Now atomically "move" the mux socket into position */ 1335 if (link(options.control_path, orig_control_path) != 0) { 1336 if (errno != EEXIST) { 1337 fatal("%s: link mux listener %s => %s: %s", __func__, 1338 options.control_path, orig_control_path, 1339 strerror(errno)); 1340 } 1341 error("ControlSocket %s already exists, disabling multiplexing", 1342 orig_control_path); 1343 unlink(options.control_path); 1344 goto disable_mux_master; 1345 } 1346 unlink(options.control_path); 1347 free(options.control_path); 1348 options.control_path = orig_control_path; 1349 1350 set_nonblock(muxserver_sock); 1351 1352 mux_listener_channel = channel_new(ssh, "mux listener", 1353 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1354 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1355 0, options.control_path, 1); 1356 mux_listener_channel->mux_rcb = mux_master_read_cb; 1357 debug3("%s: mux listener channel %d fd %d", __func__, 1358 mux_listener_channel->self, mux_listener_channel->sock); 1359} 1360 1361/* Callback on open confirmation in mux master for a mux client session. */ 1362static void 1363mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1364{ 1365 struct mux_session_confirm_ctx *cctx = arg; 1366 const char *display; 1367 Channel *c, *cc; 1368 int i, r; 1369 struct sshbuf *reply; 1370 1371 if (cctx == NULL) 1372 fatal("%s: cctx == NULL", __func__); 1373 if ((c = channel_by_id(ssh, id)) == NULL) 1374 fatal("%s: no channel for id %d", __func__, id); 1375 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1376 fatal("%s: channel %d lacks control channel %d", __func__, 1377 id, c->ctl_chan); 1378 if ((reply = sshbuf_new()) == NULL) 1379 fatal("%s: sshbuf_new", __func__); 1380 1381 if (!success) { 1382 debug3("%s: sending failure reply", __func__); 1383 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1384 "Session open refused by peer"); 1385 goto done; 1386 } 1387 1388 display = getenv("DISPLAY"); 1389 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1390 char *proto, *data; 1391 1392 /* Get reasonable local authentication information. */ 1393 if (client_x11_get_proto(ssh, display, options.xauth_location, 1394 options.forward_x11_trusted, options.forward_x11_timeout, 1395 &proto, &data) == 0) { 1396 /* Request forwarding with authentication spoofing. */ 1397 debug("Requesting X11 forwarding with authentication " 1398 "spoofing."); 1399 x11_request_forwarding_with_spoofing(ssh, id, 1400 display, proto, data, 1); 1401 /* XXX exit_on_forward_failure */ 1402 client_expect_confirm(ssh, id, "X11 forwarding", 1403 CONFIRM_WARN); 1404 } 1405 } 1406 1407 if (cctx->want_agent_fwd && options.forward_agent) { 1408 debug("Requesting authentication agent forwarding."); 1409 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1410 packet_send(); 1411 } 1412 1413 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1414 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1415 1416 debug3("%s: sending success reply", __func__); 1417 /* prepare reply */ 1418 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1419 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1420 (r = sshbuf_put_u32(reply, c->self)) != 0) 1421 fatal("%s: reply: %s", __func__, ssh_err(r)); 1422 1423 done: 1424 /* Send reply */ 1425 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1426 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 1427 sshbuf_free(reply); 1428 1429 if (cc->mux_pause <= 0) 1430 fatal("%s: mux_pause %d", __func__, cc->mux_pause); 1431 cc->mux_pause = 0; /* start processing messages again */ 1432 c->open_confirm_ctx = NULL; 1433 sshbuf_free(cctx->cmd); 1434 free(cctx->term); 1435 if (cctx->env != NULL) { 1436 for (i = 0; cctx->env[i] != NULL; i++) 1437 free(cctx->env[i]); 1438 free(cctx->env); 1439 } 1440 free(cctx); 1441} 1442 1443/* ** Multiplexing client support */ 1444 1445/* Exit signal handler */ 1446static void 1447control_client_sighandler(int signo) 1448{ 1449 muxclient_terminate = signo; 1450} 1451 1452/* 1453 * Relay signal handler - used to pass some signals from mux client to 1454 * mux master. 1455 */ 1456static void 1457control_client_sigrelay(int signo) 1458{ 1459 int save_errno = errno; 1460 1461 if (muxserver_pid > 1) 1462 kill(muxserver_pid, signo); 1463 1464 errno = save_errno; 1465} 1466 1467static int 1468mux_client_read(int fd, struct sshbuf *b, size_t need) 1469{ 1470 size_t have; 1471 ssize_t len; 1472 u_char *p; 1473 struct pollfd pfd; 1474 int r; 1475 1476 pfd.fd = fd; 1477 pfd.events = POLLIN; 1478 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1479 fatal("%s: reserve: %s", __func__, ssh_err(r)); 1480 for (have = 0; have < need; ) { 1481 if (muxclient_terminate) { 1482 errno = EINTR; 1483 return -1; 1484 } 1485 len = read(fd, p + have, need - have); 1486 if (len < 0) { 1487 switch (errno) { 1488#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1489 case EWOULDBLOCK: 1490#endif 1491 case EAGAIN: 1492 (void)poll(&pfd, 1, -1); 1493 /* FALLTHROUGH */ 1494 case EINTR: 1495 continue; 1496 default: 1497 return -1; 1498 } 1499 } 1500 if (len == 0) { 1501 errno = EPIPE; 1502 return -1; 1503 } 1504 have += (size_t)len; 1505 } 1506 return 0; 1507} 1508 1509static int 1510mux_client_write_packet(int fd, struct sshbuf *m) 1511{ 1512 struct sshbuf *queue; 1513 u_int have, need; 1514 int r, oerrno, len; 1515 const u_char *ptr; 1516 struct pollfd pfd; 1517 1518 pfd.fd = fd; 1519 pfd.events = POLLOUT; 1520 if ((queue = sshbuf_new()) == NULL) 1521 fatal("%s: sshbuf_new", __func__); 1522 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1523 fatal("%s: sshbuf_put_stringb: %s", __func__, ssh_err(r)); 1524 1525 need = sshbuf_len(queue); 1526 ptr = sshbuf_ptr(queue); 1527 1528 for (have = 0; have < need; ) { 1529 if (muxclient_terminate) { 1530 sshbuf_free(queue); 1531 errno = EINTR; 1532 return -1; 1533 } 1534 len = write(fd, ptr + have, need - have); 1535 if (len < 0) { 1536 switch (errno) { 1537#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) 1538 case EWOULDBLOCK: 1539#endif 1540 case EAGAIN: 1541 (void)poll(&pfd, 1, -1); 1542 /* FALLTHROUGH */ 1543 case EINTR: 1544 continue; 1545 default: 1546 oerrno = errno; 1547 sshbuf_free(queue); 1548 errno = oerrno; 1549 return -1; 1550 } 1551 } 1552 if (len == 0) { 1553 sshbuf_free(queue); 1554 errno = EPIPE; 1555 return -1; 1556 } 1557 have += (u_int)len; 1558 } 1559 sshbuf_free(queue); 1560 return 0; 1561} 1562 1563static int 1564mux_client_read_packet(int fd, struct sshbuf *m) 1565{ 1566 struct sshbuf *queue; 1567 size_t need, have; 1568 const u_char *ptr; 1569 int r, oerrno; 1570 1571 if ((queue = sshbuf_new()) == NULL) 1572 fatal("%s: sshbuf_new", __func__); 1573 if (mux_client_read(fd, queue, 4) != 0) { 1574 if ((oerrno = errno) == EPIPE) 1575 debug3("%s: read header failed: %s", __func__, 1576 strerror(errno)); 1577 sshbuf_free(queue); 1578 errno = oerrno; 1579 return -1; 1580 } 1581 need = PEEK_U32(sshbuf_ptr(queue)); 1582 if (mux_client_read(fd, queue, need) != 0) { 1583 oerrno = errno; 1584 debug3("%s: read body failed: %s", __func__, strerror(errno)); 1585 sshbuf_free(queue); 1586 errno = oerrno; 1587 return -1; 1588 } 1589 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1590 (r = sshbuf_put(m, ptr, have)) != 0) 1591 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1592 sshbuf_free(queue); 1593 return 0; 1594} 1595 1596static int 1597mux_client_hello_exchange(int fd) 1598{ 1599 struct sshbuf *m; 1600 u_int type, ver; 1601 int r, ret = -1; 1602 1603 if ((m = sshbuf_new()) == NULL) 1604 fatal("%s: sshbuf_new", __func__); 1605 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1606 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1607 fatal("%s: hello: %s", __func__, ssh_err(r)); 1608 /* no extensions */ 1609 1610 if (mux_client_write_packet(fd, m) != 0) { 1611 debug("%s: write packet: %s", __func__, strerror(errno)); 1612 goto out; 1613 } 1614 1615 sshbuf_reset(m); 1616 1617 /* Read their HELLO */ 1618 if (mux_client_read_packet(fd, m) != 0) { 1619 debug("%s: read packet failed", __func__); 1620 goto out; 1621 } 1622 1623 if ((r = sshbuf_get_u32(m, &type)) != 0) 1624 fatal("%s: decode type: %s", __func__, ssh_err(r)); 1625 if (type != MUX_MSG_HELLO) { 1626 error("%s: expected HELLO (%u) received %u", 1627 __func__, MUX_MSG_HELLO, type); 1628 goto out; 1629 } 1630 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1631 fatal("%s: decode version: %s", __func__, ssh_err(r)); 1632 if (ver != SSHMUX_VER) { 1633 error("Unsupported multiplexing protocol version %d " 1634 "(expected %d)", ver, SSHMUX_VER); 1635 goto out; 1636 } 1637 debug2("%s: master version %u", __func__, ver); 1638 /* No extensions are presently defined */ 1639 while (sshbuf_len(m) > 0) { 1640 char *name = NULL; 1641 1642 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1643 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1644 error("%s: malformed extension: %s", 1645 __func__, ssh_err(r)); 1646 goto out; 1647 } 1648 debug2("Unrecognised master extension \"%s\"", name); 1649 free(name); 1650 } 1651 /* success */ 1652 ret = 0; 1653 out: 1654 sshbuf_free(m); 1655 return ret; 1656} 1657 1658static u_int 1659mux_client_request_alive(int fd) 1660{ 1661 struct sshbuf *m; 1662 char *e; 1663 u_int pid, type, rid; 1664 int r; 1665 1666 debug3("%s: entering", __func__); 1667 1668 if ((m = sshbuf_new()) == NULL) 1669 fatal("%s: sshbuf_new", __func__); 1670 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1671 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1672 fatal("%s: request: %s", __func__, ssh_err(r)); 1673 1674 if (mux_client_write_packet(fd, m) != 0) 1675 fatal("%s: write packet: %s", __func__, strerror(errno)); 1676 1677 sshbuf_reset(m); 1678 1679 /* Read their reply */ 1680 if (mux_client_read_packet(fd, m) != 0) { 1681 sshbuf_free(m); 1682 return 0; 1683 } 1684 1685 if ((r = sshbuf_get_u32(m, &type)) != 0) 1686 fatal("%s: decode type: %s", __func__, ssh_err(r)); 1687 if (type != MUX_S_ALIVE) { 1688 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1689 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1690 fatal("%s: master returned error: %s", __func__, e); 1691 } 1692 1693 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1694 fatal("%s: decode remote ID: %s", __func__, ssh_err(r)); 1695 if (rid != muxclient_request_id) 1696 fatal("%s: out of sequence reply: my id %u theirs %u", 1697 __func__, muxclient_request_id, rid); 1698 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1699 fatal("%s: decode PID: %s", __func__, ssh_err(r)); 1700 sshbuf_free(m); 1701 1702 debug3("%s: done pid = %u", __func__, pid); 1703 1704 muxclient_request_id++; 1705 1706 return pid; 1707} 1708 1709static void 1710mux_client_request_terminate(int fd) 1711{ 1712 struct sshbuf *m; 1713 char *e; 1714 u_int type, rid; 1715 int r; 1716 1717 debug3("%s: entering", __func__); 1718 1719 if ((m = sshbuf_new()) == NULL) 1720 fatal("%s: sshbuf_new", __func__); 1721 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1722 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1723 fatal("%s: request: %s", __func__, ssh_err(r)); 1724 1725 if (mux_client_write_packet(fd, m) != 0) 1726 fatal("%s: write packet: %s", __func__, strerror(errno)); 1727 1728 sshbuf_reset(m); 1729 1730 /* Read their reply */ 1731 if (mux_client_read_packet(fd, m) != 0) { 1732 /* Remote end exited already */ 1733 if (errno == EPIPE) { 1734 sshbuf_free(m); 1735 return; 1736 } 1737 fatal("%s: read from master failed: %s", 1738 __func__, strerror(errno)); 1739 } 1740 1741 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1742 (r = sshbuf_get_u32(m, &rid)) != 0) 1743 fatal("%s: decode: %s", __func__, ssh_err(r)); 1744 if (rid != muxclient_request_id) 1745 fatal("%s: out of sequence reply: my id %u theirs %u", 1746 __func__, muxclient_request_id, rid); 1747 switch (type) { 1748 case MUX_S_OK: 1749 break; 1750 case MUX_S_PERMISSION_DENIED: 1751 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1752 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1753 fatal("Master refused termination request: %s", e); 1754 case MUX_S_FAILURE: 1755 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1756 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1757 fatal("%s: termination request failed: %s", __func__, e); 1758 default: 1759 fatal("%s: unexpected response from master 0x%08x", 1760 __func__, type); 1761 } 1762 sshbuf_free(m); 1763 muxclient_request_id++; 1764} 1765 1766static int 1767mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1768{ 1769 struct sshbuf *m; 1770 char *e, *fwd_desc; 1771 const char *lhost, *chost; 1772 u_int type, rid; 1773 int r; 1774 1775 fwd_desc = format_forward(ftype, fwd); 1776 debug("Requesting %s %s", 1777 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1778 free(fwd_desc); 1779 1780 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1781 if (fwd->listen_path != NULL) 1782 lhost = fwd->listen_path; 1783 else if (fwd->listen_host == NULL) 1784 lhost = ""; 1785 else if (*fwd->listen_host == '\0') 1786 lhost = "*"; 1787 else 1788 lhost = fwd->listen_host; 1789 1790 if (fwd->connect_path != NULL) 1791 chost = fwd->connect_path; 1792 else if (fwd->connect_host == NULL) 1793 chost = ""; 1794 else 1795 chost = fwd->connect_host; 1796 1797 if ((m = sshbuf_new()) == NULL) 1798 fatal("%s: sshbuf_new", __func__); 1799 if ((r = sshbuf_put_u32(m, type)) != 0 || 1800 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1801 (r = sshbuf_put_u32(m, ftype)) != 0 || 1802 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1803 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1804 (r = sshbuf_put_cstring(m, chost)) != 0 || 1805 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1806 fatal("%s: request: %s", __func__, ssh_err(r)); 1807 1808 if (mux_client_write_packet(fd, m) != 0) 1809 fatal("%s: write packet: %s", __func__, strerror(errno)); 1810 1811 sshbuf_reset(m); 1812 1813 /* Read their reply */ 1814 if (mux_client_read_packet(fd, m) != 0) { 1815 sshbuf_free(m); 1816 return -1; 1817 } 1818 1819 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1820 (r = sshbuf_get_u32(m, &rid)) != 0) 1821 fatal("%s: decode: %s", __func__, ssh_err(r)); 1822 if (rid != muxclient_request_id) 1823 fatal("%s: out of sequence reply: my id %u theirs %u", 1824 __func__, muxclient_request_id, rid); 1825 1826 switch (type) { 1827 case MUX_S_OK: 1828 break; 1829 case MUX_S_REMOTE_PORT: 1830 if (cancel_flag) 1831 fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); 1832 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1833 fatal("%s: decode port: %s", __func__, ssh_err(r)); 1834 verbose("Allocated port %u for remote forward to %s:%d", 1835 fwd->allocated_port, 1836 fwd->connect_host ? fwd->connect_host : "", 1837 fwd->connect_port); 1838 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1839 fprintf(stdout, "%i\n", fwd->allocated_port); 1840 break; 1841 case MUX_S_PERMISSION_DENIED: 1842 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1843 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1844 sshbuf_free(m); 1845 error("Master refused forwarding request: %s", e); 1846 return -1; 1847 case MUX_S_FAILURE: 1848 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1849 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1850 sshbuf_free(m); 1851 error("%s: forwarding request failed: %s", __func__, e); 1852 return -1; 1853 default: 1854 fatal("%s: unexpected response from master 0x%08x", 1855 __func__, type); 1856 } 1857 sshbuf_free(m); 1858 1859 muxclient_request_id++; 1860 return 0; 1861} 1862 1863static int 1864mux_client_forwards(int fd, int cancel_flag) 1865{ 1866 int i, ret = 0; 1867 1868 debug3("%s: %s forwardings: %d local, %d remote", __func__, 1869 cancel_flag ? "cancel" : "request", 1870 options.num_local_forwards, options.num_remote_forwards); 1871 1872 /* XXX ExitOnForwardingFailure */ 1873 for (i = 0; i < options.num_local_forwards; i++) { 1874 if (mux_client_forward(fd, cancel_flag, 1875 options.local_forwards[i].connect_port == 0 ? 1876 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1877 options.local_forwards + i) != 0) 1878 ret = -1; 1879 } 1880 for (i = 0; i < options.num_remote_forwards; i++) { 1881 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1882 options.remote_forwards + i) != 0) 1883 ret = -1; 1884 } 1885 return ret; 1886} 1887 1888static int 1889mux_client_request_session(int fd) 1890{ 1891 struct sshbuf *m; 1892 char *e; 1893 const char *term; 1894 u_int echar, rid, sid, esid, exitval, type, exitval_seen; 1895 extern char **environ; 1896 int r, i, devnull, rawmode; 1897 1898 debug3("%s: entering", __func__); 1899 1900 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1901 error("%s: master alive request failed", __func__); 1902 return -1; 1903 } 1904 1905 signal(SIGPIPE, SIG_IGN); 1906 1907 if (stdin_null_flag) { 1908 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1909 fatal("open(/dev/null): %s", strerror(errno)); 1910 if (dup2(devnull, STDIN_FILENO) == -1) 1911 fatal("dup2: %s", strerror(errno)); 1912 if (devnull > STDERR_FILENO) 1913 close(devnull); 1914 } 1915 1916 if ((term = getenv("TERM")) == NULL) 1917 term = ""; 1918 echar = 0xffffffff; 1919 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1920 echar = (u_int)options.escape_char; 1921 1922 if ((m = sshbuf_new()) == NULL) 1923 fatal("%s: sshbuf_new", __func__); 1924 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1925 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1926 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1927 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1928 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1929 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1930 (r = sshbuf_put_u32(m, subsystem_flag)) != 0 || 1931 (r = sshbuf_put_u32(m, echar)) != 0 || 1932 (r = sshbuf_put_cstring(m, term)) != 0 || 1933 (r = sshbuf_put_stringb(m, command)) != 0) 1934 fatal("%s: request: %s", __func__, ssh_err(r)); 1935 1936 /* Pass environment */ 1937 if (options.num_send_env > 0 && environ != NULL) { 1938 for (i = 0; environ[i] != NULL; i++) { 1939 if (!env_permitted(environ[i])) 1940 continue; 1941 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1942 fatal("%s: request: %s", __func__, ssh_err(r)); 1943 } 1944 } 1945 for (i = 0; i < options.num_setenv; i++) { 1946 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1947 fatal("%s: request: %s", __func__, ssh_err(r)); 1948 } 1949 1950 if (mux_client_write_packet(fd, m) != 0) 1951 fatal("%s: write packet: %s", __func__, strerror(errno)); 1952 1953 /* Send the stdio file descriptors */ 1954 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1955 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1956 mm_send_fd(fd, STDERR_FILENO) == -1) 1957 fatal("%s: send fds failed", __func__); 1958 1959 debug3("%s: session request sent", __func__); 1960 1961 /* Read their reply */ 1962 sshbuf_reset(m); 1963 if (mux_client_read_packet(fd, m) != 0) { 1964 error("%s: read from master failed: %s", 1965 __func__, strerror(errno)); 1966 sshbuf_free(m); 1967 return -1; 1968 } 1969 1970 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1971 (r = sshbuf_get_u32(m, &rid)) != 0) 1972 fatal("%s: decode: %s", __func__, ssh_err(r)); 1973 if (rid != muxclient_request_id) 1974 fatal("%s: out of sequence reply: my id %u theirs %u", 1975 __func__, muxclient_request_id, rid); 1976 1977 switch (type) { 1978 case MUX_S_SESSION_OPENED: 1979 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1980 fatal("%s: decode ID: %s", __func__, ssh_err(r)); 1981 break; 1982 case MUX_S_PERMISSION_DENIED: 1983 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1984 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1985 error("Master refused session request: %s", e); 1986 sshbuf_free(m); 1987 return -1; 1988 case MUX_S_FAILURE: 1989 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1990 fatal("%s: decode error: %s", __func__, ssh_err(r)); 1991 error("%s: session request failed: %s", __func__, e); 1992 sshbuf_free(m); 1993 return -1; 1994 default: 1995 sshbuf_free(m); 1996 error("%s: unexpected response from master 0x%08x", 1997 __func__, type); 1998 return -1; 1999 } 2000 muxclient_request_id++; 2001 2002 if (pledge("stdio proc tty", NULL) == -1) 2003 fatal("%s pledge(): %s", __func__, strerror(errno)); 2004 platform_pledge_mux(); 2005 2006 signal(SIGHUP, control_client_sighandler); 2007 signal(SIGINT, control_client_sighandler); 2008 signal(SIGTERM, control_client_sighandler); 2009 signal(SIGWINCH, control_client_sigrelay); 2010 2011 rawmode = tty_flag; 2012 if (tty_flag) 2013 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2014 2015 /* 2016 * Stick around until the controlee closes the client_fd. 2017 * Before it does, it is expected to write an exit message. 2018 * This process must read the value and wait for the closure of 2019 * the client_fd; if this one closes early, the multiplex master will 2020 * terminate early too (possibly losing data). 2021 */ 2022 for (exitval = 255, exitval_seen = 0;;) { 2023 sshbuf_reset(m); 2024 if (mux_client_read_packet(fd, m) != 0) 2025 break; 2026 if ((r = sshbuf_get_u32(m, &type)) != 0) 2027 fatal("%s: decode type: %s", __func__, ssh_err(r)); 2028 switch (type) { 2029 case MUX_S_TTY_ALLOC_FAIL: 2030 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2031 fatal("%s: decode ID: %s", 2032 __func__, ssh_err(r)); 2033 if (esid != sid) 2034 fatal("%s: tty alloc fail on unknown session: " 2035 "my id %u theirs %u", 2036 __func__, sid, esid); 2037 leave_raw_mode(options.request_tty == 2038 REQUEST_TTY_FORCE); 2039 rawmode = 0; 2040 continue; 2041 case MUX_S_EXIT_MESSAGE: 2042 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2043 fatal("%s: decode ID: %s", 2044 __func__, ssh_err(r)); 2045 if (esid != sid) 2046 fatal("%s: exit on unknown session: " 2047 "my id %u theirs %u", 2048 __func__, sid, esid); 2049 if (exitval_seen) 2050 fatal("%s: exitval sent twice", __func__); 2051 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2052 fatal("%s: decode exit value: %s", 2053 __func__, ssh_err(r)); 2054 exitval_seen = 1; 2055 continue; 2056 default: 2057 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2058 fatal("%s: decode error: %s", 2059 __func__, ssh_err(r)); 2060 fatal("%s: master returned error: %s", __func__, e); 2061 } 2062 } 2063 2064 close(fd); 2065 if (rawmode) 2066 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2067 2068 if (muxclient_terminate) { 2069 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2070 exitval = 255; 2071 } else if (!exitval_seen) { 2072 debug2("Control master terminated unexpectedly"); 2073 exitval = 255; 2074 } else 2075 debug2("Received exit status from master %d", exitval); 2076 2077 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 2078 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2079 2080 exit(exitval); 2081} 2082 2083static int 2084mux_client_proxy(int fd) 2085{ 2086 struct sshbuf *m; 2087 char *e; 2088 u_int type, rid; 2089 int r; 2090 2091 if ((m = sshbuf_new()) == NULL) 2092 fatal("%s: sshbuf_new", __func__); 2093 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2094 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2095 fatal("%s: request: %s", __func__, ssh_err(r)); 2096 if (mux_client_write_packet(fd, m) != 0) 2097 fatal("%s: write packet: %s", __func__, strerror(errno)); 2098 2099 sshbuf_reset(m); 2100 2101 /* Read their reply */ 2102 if (mux_client_read_packet(fd, m) != 0) { 2103 sshbuf_free(m); 2104 return 0; 2105 } 2106 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2107 (r = sshbuf_get_u32(m, &rid)) != 0) 2108 fatal("%s: decode: %s", __func__, ssh_err(r)); 2109 if (rid != muxclient_request_id) 2110 fatal("%s: out of sequence reply: my id %u theirs %u", 2111 __func__, muxclient_request_id, rid); 2112 if (type != MUX_S_PROXY) { 2113 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2114 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2115 fatal("%s: master returned error: %s", __func__, e); 2116 } 2117 sshbuf_free(m); 2118 2119 debug3("%s: done", __func__); 2120 muxclient_request_id++; 2121 return 0; 2122} 2123 2124static int 2125mux_client_request_stdio_fwd(int fd) 2126{ 2127 struct sshbuf *m; 2128 char *e; 2129 u_int type, rid, sid; 2130 int r, devnull; 2131 2132 debug3("%s: entering", __func__); 2133 2134 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2135 error("%s: master alive request failed", __func__); 2136 return -1; 2137 } 2138 2139 signal(SIGPIPE, SIG_IGN); 2140 2141 if (stdin_null_flag) { 2142 if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) 2143 fatal("open(/dev/null): %s", strerror(errno)); 2144 if (dup2(devnull, STDIN_FILENO) == -1) 2145 fatal("dup2: %s", strerror(errno)); 2146 if (devnull > STDERR_FILENO) 2147 close(devnull); 2148 } 2149 2150 if ((m = sshbuf_new()) == NULL) 2151 fatal("%s: sshbuf_new", __func__); 2152 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2153 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2154 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2155 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2156 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2157 fatal("%s: request: %s", __func__, ssh_err(r)); 2158 2159 if (mux_client_write_packet(fd, m) != 0) 2160 fatal("%s: write packet: %s", __func__, strerror(errno)); 2161 2162 /* Send the stdio file descriptors */ 2163 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2164 mm_send_fd(fd, STDOUT_FILENO) == -1) 2165 fatal("%s: send fds failed", __func__); 2166 2167 if (pledge("stdio proc tty", NULL) == -1) 2168 fatal("%s pledge(): %s", __func__, strerror(errno)); 2169 platform_pledge_mux(); 2170 2171 debug3("%s: stdio forward request sent", __func__); 2172 2173 /* Read their reply */ 2174 sshbuf_reset(m); 2175 2176 if (mux_client_read_packet(fd, m) != 0) { 2177 error("%s: read from master failed: %s", 2178 __func__, strerror(errno)); 2179 sshbuf_free(m); 2180 return -1; 2181 } 2182 2183 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2184 (r = sshbuf_get_u32(m, &rid)) != 0) 2185 fatal("%s: decode: %s", __func__, ssh_err(r)); 2186 if (rid != muxclient_request_id) 2187 fatal("%s: out of sequence reply: my id %u theirs %u", 2188 __func__, muxclient_request_id, rid); 2189 switch (type) { 2190 case MUX_S_SESSION_OPENED: 2191 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2192 fatal("%s: decode ID: %s", __func__, ssh_err(r)); 2193 debug("%s: master session id: %u", __func__, sid); 2194 break; 2195 case MUX_S_PERMISSION_DENIED: 2196 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2197 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2198 sshbuf_free(m); 2199 fatal("Master refused stdio forwarding request: %s", e); 2200 case MUX_S_FAILURE: 2201 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2202 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2203 sshbuf_free(m); 2204 fatal("Stdio forwarding request failed: %s", e); 2205 default: 2206 sshbuf_free(m); 2207 error("%s: unexpected response from master 0x%08x", 2208 __func__, type); 2209 return -1; 2210 } 2211 muxclient_request_id++; 2212 2213 signal(SIGHUP, control_client_sighandler); 2214 signal(SIGINT, control_client_sighandler); 2215 signal(SIGTERM, control_client_sighandler); 2216 signal(SIGWINCH, control_client_sigrelay); 2217 2218 /* 2219 * Stick around until the controlee closes the client_fd. 2220 */ 2221 sshbuf_reset(m); 2222 if (mux_client_read_packet(fd, m) != 0) { 2223 if (errno == EPIPE || 2224 (errno == EINTR && muxclient_terminate != 0)) 2225 return 0; 2226 fatal("%s: mux_client_read_packet: %s", 2227 __func__, strerror(errno)); 2228 } 2229 fatal("%s: master returned unexpected message %u", __func__, type); 2230} 2231 2232static void 2233mux_client_request_stop_listening(int fd) 2234{ 2235 struct sshbuf *m; 2236 char *e; 2237 u_int type, rid; 2238 int r; 2239 2240 debug3("%s: entering", __func__); 2241 2242 if ((m = sshbuf_new()) == NULL) 2243 fatal("%s: sshbuf_new", __func__); 2244 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2245 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2246 fatal("%s: request: %s", __func__, ssh_err(r)); 2247 2248 if (mux_client_write_packet(fd, m) != 0) 2249 fatal("%s: write packet: %s", __func__, strerror(errno)); 2250 2251 sshbuf_reset(m); 2252 2253 /* Read their reply */ 2254 if (mux_client_read_packet(fd, m) != 0) 2255 fatal("%s: read from master failed: %s", 2256 __func__, strerror(errno)); 2257 2258 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2259 (r = sshbuf_get_u32(m, &rid)) != 0) 2260 fatal("%s: decode: %s", __func__, ssh_err(r)); 2261 if (rid != muxclient_request_id) 2262 fatal("%s: out of sequence reply: my id %u theirs %u", 2263 __func__, muxclient_request_id, rid); 2264 2265 switch (type) { 2266 case MUX_S_OK: 2267 break; 2268 case MUX_S_PERMISSION_DENIED: 2269 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2270 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2271 fatal("Master refused stop listening request: %s", e); 2272 case MUX_S_FAILURE: 2273 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2274 fatal("%s: decode error: %s", __func__, ssh_err(r)); 2275 fatal("%s: stop listening request failed: %s", __func__, e); 2276 default: 2277 fatal("%s: unexpected response from master 0x%08x", 2278 __func__, type); 2279 } 2280 sshbuf_free(m); 2281 muxclient_request_id++; 2282} 2283 2284/* Multiplex client main loop. */ 2285int 2286muxclient(const char *path) 2287{ 2288 struct sockaddr_un addr; 2289 int sock; 2290 u_int pid; 2291 2292 if (muxclient_command == 0) { 2293 if (options.stdio_forward_host != NULL) 2294 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2295 else 2296 muxclient_command = SSHMUX_COMMAND_OPEN; 2297 } 2298 2299 switch (options.control_master) { 2300 case SSHCTL_MASTER_AUTO: 2301 case SSHCTL_MASTER_AUTO_ASK: 2302 debug("auto-mux: Trying existing master"); 2303 /* FALLTHROUGH */ 2304 case SSHCTL_MASTER_NO: 2305 break; 2306 default: 2307 return -1; 2308 } 2309 2310 memset(&addr, '\0', sizeof(addr)); 2311 addr.sun_family = AF_UNIX; 2312 2313 if (strlcpy(addr.sun_path, path, 2314 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2315 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2316 (unsigned int)sizeof(addr.sun_path)); 2317 2318 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) 2319 fatal("%s socket(): %s", __func__, strerror(errno)); 2320 2321 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2322 switch (muxclient_command) { 2323 case SSHMUX_COMMAND_OPEN: 2324 case SSHMUX_COMMAND_STDIO_FWD: 2325 break; 2326 default: 2327 fatal("Control socket connect(%.100s): %s", path, 2328 strerror(errno)); 2329 } 2330 if (errno == ECONNREFUSED && 2331 options.control_master != SSHCTL_MASTER_NO) { 2332 debug("Stale control socket %.100s, unlinking", path); 2333 unlink(path); 2334 } else if (errno == ENOENT) { 2335 debug("Control socket \"%.100s\" does not exist", path); 2336 } else { 2337 error("Control socket connect(%.100s): %s", path, 2338 strerror(errno)); 2339 } 2340 close(sock); 2341 return -1; 2342 } 2343 set_nonblock(sock); 2344 2345 if (mux_client_hello_exchange(sock) != 0) { 2346 error("%s: master hello exchange failed", __func__); 2347 close(sock); 2348 return -1; 2349 } 2350 2351 switch (muxclient_command) { 2352 case SSHMUX_COMMAND_ALIVE_CHECK: 2353 if ((pid = mux_client_request_alive(sock)) == 0) 2354 fatal("%s: master alive check failed", __func__); 2355 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2356 exit(0); 2357 case SSHMUX_COMMAND_TERMINATE: 2358 mux_client_request_terminate(sock); 2359 if (options.log_level != SYSLOG_LEVEL_QUIET) 2360 fprintf(stderr, "Exit request sent.\r\n"); 2361 exit(0); 2362 case SSHMUX_COMMAND_FORWARD: 2363 if (mux_client_forwards(sock, 0) != 0) 2364 fatal("%s: master forward request failed", __func__); 2365 exit(0); 2366 case SSHMUX_COMMAND_OPEN: 2367 if (mux_client_forwards(sock, 0) != 0) { 2368 error("%s: master forward request failed", __func__); 2369 return -1; 2370 } 2371 mux_client_request_session(sock); 2372 return -1; 2373 case SSHMUX_COMMAND_STDIO_FWD: 2374 mux_client_request_stdio_fwd(sock); 2375 exit(0); 2376 case SSHMUX_COMMAND_STOP: 2377 mux_client_request_stop_listening(sock); 2378 if (options.log_level != SYSLOG_LEVEL_QUIET) 2379 fprintf(stderr, "Stop listening request sent.\r\n"); 2380 exit(0); 2381 case SSHMUX_COMMAND_CANCEL_FWD: 2382 if (mux_client_forwards(sock, 1) != 0) 2383 error("%s: master cancel forward request failed", 2384 __func__); 2385 exit(0); 2386 case SSHMUX_COMMAND_PROXY: 2387 mux_client_proxy(sock); 2388 return (sock); 2389 default: 2390 fatal("unrecognised muxclient_command %d", muxclient_command); 2391 } 2392} 2393