mux.c revision 1.29
1/* $NetBSD: mux.c,v 1.29 2021/04/19 14:40:15 christos Exp $ */ 2/* $OpenBSD: mux.c,v 1.87 2021/04/03 06:18:40 djm Exp $ */ 3 4/* 5 * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20/* ssh session multiplexing support */ 21 22#include "includes.h" 23__RCSID("$NetBSD: mux.c,v 1.29 2021/04/19 14:40:15 christos Exp $"); 24#include <sys/types.h> 25#include <sys/queue.h> 26#include <sys/stat.h> 27#include <sys/socket.h> 28#include <sys/un.h> 29 30#include <errno.h> 31#include <fcntl.h> 32#include <poll.h> 33#include <signal.h> 34#include <stdarg.h> 35#include <stddef.h> 36#include <stdlib.h> 37#include <stdio.h> 38#include <string.h> 39#include <unistd.h> 40#include <util.h> 41#include <paths.h> 42 43#include "atomicio.h" 44#include "xmalloc.h" 45#include "log.h" 46#include "ssh.h" 47#include "ssh2.h" 48#include "pathnames.h" 49#include "misc.h" 50#include "match.h" 51#include "sshbuf.h" 52#include "channels.h" 53#include "msg.h" 54#include "packet.h" 55#include "monitor_fdpass.h" 56#include "sshpty.h" 57#include "sshkey.h" 58#include "readconf.h" 59#include "clientloop.h" 60#include "ssherr.h" 61 62/* from ssh.c */ 63extern int tty_flag; 64extern Options options; 65extern int stdin_null_flag; 66extern char *host; 67extern int subsystem_flag; 68extern struct sshbuf *command; 69extern volatile sig_atomic_t quit_pending; 70 71/* Context for session open confirmation callback */ 72struct mux_session_confirm_ctx { 73 u_int want_tty; 74 u_int want_subsys; 75 u_int want_x_fwd; 76 u_int want_agent_fwd; 77 struct sshbuf *cmd; 78 char *term; 79 struct termios tio; 80 char **env; 81 u_int rid; 82}; 83 84/* Context for stdio fwd open confirmation callback */ 85struct mux_stdio_confirm_ctx { 86 u_int rid; 87}; 88 89/* Context for global channel callback */ 90struct mux_channel_confirm_ctx { 91 u_int cid; /* channel id */ 92 u_int rid; /* request id */ 93 int fid; /* forward id */ 94}; 95 96/* fd to control socket */ 97int muxserver_sock = -1; 98 99/* client request id */ 100u_int muxclient_request_id = 0; 101 102/* Multiplexing control command */ 103u_int muxclient_command = 0; 104 105/* Set when signalled. */ 106static volatile sig_atomic_t muxclient_terminate = 0; 107 108/* PID of multiplex server */ 109static u_int muxserver_pid = 0; 110 111static Channel *mux_listener_channel = NULL; 112 113struct mux_master_state { 114 int hello_rcvd; 115}; 116 117/* mux protocol messages */ 118#define MUX_MSG_HELLO 0x00000001 119#define MUX_C_NEW_SESSION 0x10000002 120#define MUX_C_ALIVE_CHECK 0x10000004 121#define MUX_C_TERMINATE 0x10000005 122#define MUX_C_OPEN_FWD 0x10000006 123#define MUX_C_CLOSE_FWD 0x10000007 124#define MUX_C_NEW_STDIO_FWD 0x10000008 125#define MUX_C_STOP_LISTENING 0x10000009 126#define MUX_C_PROXY 0x1000000f 127#define MUX_S_OK 0x80000001 128#define MUX_S_PERMISSION_DENIED 0x80000002 129#define MUX_S_FAILURE 0x80000003 130#define MUX_S_EXIT_MESSAGE 0x80000004 131#define MUX_S_ALIVE 0x80000005 132#define MUX_S_SESSION_OPENED 0x80000006 133#define MUX_S_REMOTE_PORT 0x80000007 134#define MUX_S_TTY_ALLOC_FAIL 0x80000008 135#define MUX_S_PROXY 0x8000000f 136 137/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ 138#define MUX_FWD_LOCAL 1 139#define MUX_FWD_REMOTE 2 140#define MUX_FWD_DYNAMIC 3 141 142static void mux_session_confirm(struct ssh *, int, int, void *); 143static void mux_stdio_confirm(struct ssh *, int, int, void *); 144 145static int mux_master_process_hello(struct ssh *, u_int, 146 Channel *, struct sshbuf *, struct sshbuf *); 147static int mux_master_process_new_session(struct ssh *, u_int, 148 Channel *, struct sshbuf *, struct sshbuf *); 149static int mux_master_process_alive_check(struct ssh *, u_int, 150 Channel *, struct sshbuf *, struct sshbuf *); 151static int mux_master_process_terminate(struct ssh *, u_int, 152 Channel *, struct sshbuf *, struct sshbuf *); 153static int mux_master_process_open_fwd(struct ssh *, u_int, 154 Channel *, struct sshbuf *, struct sshbuf *); 155static int mux_master_process_close_fwd(struct ssh *, u_int, 156 Channel *, struct sshbuf *, struct sshbuf *); 157static int mux_master_process_stdio_fwd(struct ssh *, u_int, 158 Channel *, struct sshbuf *, struct sshbuf *); 159static int mux_master_process_stop_listening(struct ssh *, u_int, 160 Channel *, struct sshbuf *, struct sshbuf *); 161static int mux_master_process_proxy(struct ssh *, u_int, 162 Channel *, struct sshbuf *, struct sshbuf *); 163 164static const struct { 165 u_int type; 166 int (*handler)(struct ssh *, u_int, Channel *, 167 struct sshbuf *, struct sshbuf *); 168} mux_master_handlers[] = { 169 { MUX_MSG_HELLO, mux_master_process_hello }, 170 { MUX_C_NEW_SESSION, mux_master_process_new_session }, 171 { MUX_C_ALIVE_CHECK, mux_master_process_alive_check }, 172 { MUX_C_TERMINATE, mux_master_process_terminate }, 173 { MUX_C_OPEN_FWD, mux_master_process_open_fwd }, 174 { MUX_C_CLOSE_FWD, mux_master_process_close_fwd }, 175 { MUX_C_NEW_STDIO_FWD, mux_master_process_stdio_fwd }, 176 { MUX_C_STOP_LISTENING, mux_master_process_stop_listening }, 177 { MUX_C_PROXY, mux_master_process_proxy }, 178 { 0, NULL } 179}; 180 181/* Cleanup callback fired on closure of mux client _session_ channel */ 182/* ARGSUSED */ 183static void 184mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused) 185{ 186 Channel *cc, *c = channel_by_id(ssh, cid); 187 188 debug3_f("entering for channel %d", cid); 189 if (c == NULL) 190 fatal_f("channel_by_id(%i) == NULL", cid); 191 if (c->ctl_chan != -1) { 192 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 193 fatal_f("channel %d missing control channel %d", 194 c->self, c->ctl_chan); 195 c->ctl_chan = -1; 196 cc->remote_id = 0; 197 cc->have_remote_id = 0; 198 chan_rcvd_oclose(ssh, cc); 199 } 200 channel_cancel_cleanup(ssh, c->self); 201} 202 203/* Cleanup callback fired on closure of mux client _control_ channel */ 204/* ARGSUSED */ 205static void 206mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused) 207{ 208 Channel *sc, *c = channel_by_id(ssh, cid); 209 210 debug3_f("entering for channel %d", cid); 211 if (c == NULL) 212 fatal_f("channel_by_id(%i) == NULL", cid); 213 if (c->have_remote_id) { 214 if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) 215 fatal_f("channel %d missing session channel %u", 216 c->self, c->remote_id); 217 c->remote_id = 0; 218 c->have_remote_id = 0; 219 sc->ctl_chan = -1; 220 if (sc->type != SSH_CHANNEL_OPEN && 221 sc->type != SSH_CHANNEL_OPENING) { 222 debug2_f("channel %d: not open", sc->self); 223 chan_mark_dead(ssh, sc); 224 } else { 225 if (sc->istate == CHAN_INPUT_OPEN) 226 chan_read_failed(ssh, sc); 227 if (sc->ostate == CHAN_OUTPUT_OPEN) 228 chan_write_failed(ssh, sc); 229 } 230 } 231 channel_cancel_cleanup(ssh, c->self); 232} 233 234/* Check mux client environment variables before passing them to mux master. */ 235static int 236env_permitted(char *env) 237{ 238 int i, ret; 239 char name[1024], *cp; 240 241 if ((cp = strchr(env, '=')) == NULL || cp == env) 242 return 0; 243 ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); 244 if (ret <= 0 || (size_t)ret >= sizeof(name)) { 245 error_f("name '%.100s...' too long", env); 246 return 0; 247 } 248 249 for (i = 0; i < options.num_send_env; i++) 250 if (match_pattern(name, options.send_env[i])) 251 return 1; 252 253 return 0; 254} 255 256/* Mux master protocol message handlers */ 257 258static int 259mux_master_process_hello(struct ssh *ssh, u_int rid, 260 Channel *c, struct sshbuf *m, struct sshbuf *reply) 261{ 262 u_int ver; 263 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 264 int r; 265 266 if (state == NULL) 267 fatal_f("channel %d: c->mux_ctx == NULL", c->self); 268 if (state->hello_rcvd) { 269 error_f("HELLO received twice"); 270 return -1; 271 } 272 if ((r = sshbuf_get_u32(m, &ver)) != 0) { 273 error_fr(r, "parse"); 274 return -1; 275 } 276 if (ver != SSHMUX_VER) { 277 error_f("unsupported multiplexing protocol version %u " 278 "(expected %u)", ver, SSHMUX_VER); 279 return -1; 280 } 281 debug2_f("channel %d client version %u", c->self, ver); 282 283 /* No extensions are presently defined */ 284 while (sshbuf_len(m) > 0) { 285 char *name = NULL; 286 size_t value_len = 0; 287 288 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 289 (r = sshbuf_get_string_direct(m, NULL, &value_len)) != 0) { 290 error_fr(r, "parse extension"); 291 return -1; 292 } 293 debug2_f("Unrecognised extension \"%s\" length %zu", 294 name, value_len); 295 free(name); 296 } 297 state->hello_rcvd = 1; 298 return 0; 299} 300 301/* Enqueue a "ok" response to the reply buffer */ 302static void 303reply_ok(struct sshbuf *reply, u_int rid) 304{ 305 int r; 306 307 if ((r = sshbuf_put_u32(reply, MUX_S_OK)) != 0 || 308 (r = sshbuf_put_u32(reply, rid)) != 0) 309 fatal_fr(r, "reply"); 310} 311 312/* Enqueue an error response to the reply buffer */ 313static void 314reply_error(struct sshbuf *reply, u_int type, u_int rid, const char *msg) 315{ 316 int r; 317 318 if ((r = sshbuf_put_u32(reply, type)) != 0 || 319 (r = sshbuf_put_u32(reply, rid)) != 0 || 320 (r = sshbuf_put_cstring(reply, msg)) != 0) 321 fatal_fr(r, "reply"); 322} 323 324static int 325mux_master_process_new_session(struct ssh *ssh, u_int rid, 326 Channel *c, struct sshbuf *m, struct sshbuf *reply) 327{ 328 Channel *nc; 329 struct mux_session_confirm_ctx *cctx; 330 char *cmd, *cp; 331 u_int i, j, env_len, escape_char, window, packetmax; 332 int r, new_fd[3]; 333 334 /* Reply for SSHMUX_COMMAND_OPEN */ 335 cctx = xcalloc(1, sizeof(*cctx)); 336 cctx->term = NULL; 337 cctx->rid = rid; 338 cmd = NULL; 339 cctx->env = NULL; 340 env_len = 0; 341 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 342 (r = sshbuf_get_u32(m, &cctx->want_tty)) != 0 || 343 (r = sshbuf_get_u32(m, &cctx->want_x_fwd)) != 0 || 344 (r = sshbuf_get_u32(m, &cctx->want_agent_fwd)) != 0 || 345 (r = sshbuf_get_u32(m, &cctx->want_subsys)) != 0 || 346 (r = sshbuf_get_u32(m, &escape_char)) != 0 || 347 (r = sshbuf_get_cstring(m, &cctx->term, NULL)) != 0 || 348 (r = sshbuf_get_cstring(m, &cmd, NULL)) != 0) { 349 malf: 350 free(cmd); 351 for (j = 0; j < env_len; j++) 352 free(cctx->env[j]); 353 free(cctx->env); 354 free(cctx->term); 355 free(cctx); 356 error_f("malformed message"); 357 return -1; 358 } 359 360#define MUX_MAX_ENV_VARS 4096 361 while (sshbuf_len(m) > 0) { 362 if ((r = sshbuf_get_cstring(m, &cp, NULL)) != 0) 363 goto malf; 364 if (!env_permitted(cp)) { 365 free(cp); 366 continue; 367 } 368 cctx->env = xreallocarray(cctx->env, env_len + 2, 369 sizeof(*cctx->env)); 370 cctx->env[env_len++] = cp; 371 cctx->env[env_len] = NULL; 372 if (env_len > MUX_MAX_ENV_VARS) { 373 error_f(">%d environment variables received, " 374 "ignoring additional", MUX_MAX_ENV_VARS); 375 break; 376 } 377 } 378 379 debug2_f("channel %d: request tty %d, X %d, agent %d, subsys %d, " 380 "term \"%s\", cmd \"%s\", env %u", c->self, 381 cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, 382 cctx->want_subsys, cctx->term, cmd, env_len); 383 384 if ((cctx->cmd = sshbuf_new()) == NULL) 385 fatal_f("sshbuf_new"); 386 if ((r = sshbuf_put(cctx->cmd, cmd, strlen(cmd))) != 0) 387 fatal_fr(r, "sshbuf_put"); 388 free(cmd); 389 cmd = NULL; 390 391 /* Gather fds from client */ 392 for(i = 0; i < 3; i++) { 393 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 394 error_f("failed to receive fd %d from client", i); 395 for (j = 0; j < i; j++) 396 close(new_fd[j]); 397 for (j = 0; j < env_len; j++) 398 free(cctx->env[j]); 399 free(cctx->env); 400 free(cctx->term); 401 sshbuf_free(cctx->cmd); 402 free(cctx); 403 reply_error(reply, MUX_S_FAILURE, rid, 404 "did not receive file descriptors"); 405 return -1; 406 } 407 } 408 409 debug3_f("got fds stdin %d, stdout %d, stderr %d", 410 new_fd[0], new_fd[1], new_fd[2]); 411 412 /* XXX support multiple child sessions in future */ 413 if (c->have_remote_id) { 414 debug2_f("session already open"); 415 reply_error(reply, MUX_S_FAILURE, rid, 416 "Multiple sessions not supported"); 417 cleanup: 418 close(new_fd[0]); 419 close(new_fd[1]); 420 close(new_fd[2]); 421 free(cctx->term); 422 if (env_len != 0) { 423 for (i = 0; i < env_len; i++) 424 free(cctx->env[i]); 425 free(cctx->env); 426 } 427 sshbuf_free(cctx->cmd); 428 free(cctx); 429 return 0; 430 } 431 432 if (options.control_master == SSHCTL_MASTER_ASK || 433 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 434 if (!ask_permission("Allow shared connection to %s? ", host)) { 435 debug2_f("session refused by user"); 436 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 437 "Permission denied"); 438 goto cleanup; 439 } 440 } 441 442 /* Try to pick up ttymodes from client before it goes raw */ 443 if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) 444 error_f("tcgetattr: %s", strerror(errno)); 445 446 /* enable nonblocking unless tty */ 447 if (!isatty(new_fd[0])) 448 set_nonblock(new_fd[0]); 449 if (!isatty(new_fd[1])) 450 set_nonblock(new_fd[1]); 451 if (!isatty(new_fd[2])) 452 set_nonblock(new_fd[2]); 453 454 window = CHAN_SES_WINDOW_DEFAULT; 455 packetmax = CHAN_SES_PACKET_DEFAULT; 456 if (cctx->want_tty) { 457 window >>= 1; 458 packetmax >>= 1; 459 } 460 461 nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, 462 new_fd[0], new_fd[1], new_fd[2], window, packetmax, 463 CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); 464 465 nc->ctl_chan = c->self; /* link session -> control channel */ 466 c->remote_id = nc->self; /* link control -> session channel */ 467 c->have_remote_id = 1; 468 469 if (cctx->want_tty && escape_char != 0xffffffff) { 470 channel_register_filter(ssh, nc->self, 471 client_simple_escape_filter, NULL, 472 client_filter_cleanup, 473 client_new_escape_filter_ctx((int)escape_char)); 474 } 475 476 debug2_f("channel_new: %d linked to control channel %d", 477 nc->self, nc->ctl_chan); 478 479 channel_send_open(ssh, nc->self); 480 channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); 481 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 482 channel_register_cleanup(ssh, nc->self, 483 mux_master_session_cleanup_cb, 1); 484 485 /* reply is deferred, sent by mux_session_confirm */ 486 return 0; 487} 488 489static int 490mux_master_process_alive_check(struct ssh *ssh, u_int rid, 491 Channel *c, struct sshbuf *m, struct sshbuf *reply) 492{ 493 int r; 494 495 debug2_f("channel %d: alive check", c->self); 496 497 /* prepare reply */ 498 if ((r = sshbuf_put_u32(reply, MUX_S_ALIVE)) != 0 || 499 (r = sshbuf_put_u32(reply, rid)) != 0 || 500 (r = sshbuf_put_u32(reply, (u_int)getpid())) != 0) 501 fatal_fr(r, "reply"); 502 503 return 0; 504} 505 506static int 507mux_master_process_terminate(struct ssh *ssh, u_int rid, 508 Channel *c, struct sshbuf *m, struct sshbuf *reply) 509{ 510 debug2_f("channel %d: terminate request", c->self); 511 512 if (options.control_master == SSHCTL_MASTER_ASK || 513 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 514 if (!ask_permission("Terminate shared connection to %s? ", 515 host)) { 516 debug2_f("termination refused by user"); 517 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 518 "Permission denied"); 519 return 0; 520 } 521 } 522 523 quit_pending = 1; 524 reply_ok(reply, rid); 525 /* XXX exit happens too soon - message never makes it to client */ 526 return 0; 527} 528 529static char * 530format_forward(u_int ftype, struct Forward *fwd) 531{ 532 char *ret; 533 534 switch (ftype) { 535 case MUX_FWD_LOCAL: 536 xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", 537 (fwd->listen_path != NULL) ? fwd->listen_path : 538 (fwd->listen_host == NULL) ? 539 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 540 fwd->listen_host, fwd->listen_port, 541 (fwd->connect_path != NULL) ? fwd->connect_path : 542 fwd->connect_host, fwd->connect_port); 543 break; 544 case MUX_FWD_DYNAMIC: 545 xasprintf(&ret, "dynamic forward %.200s:%d -> *", 546 (fwd->listen_host == NULL) ? 547 (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : 548 fwd->listen_host, fwd->listen_port); 549 break; 550 case MUX_FWD_REMOTE: 551 xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", 552 (fwd->listen_path != NULL) ? fwd->listen_path : 553 (fwd->listen_host == NULL) ? 554 "LOCALHOST" : fwd->listen_host, 555 fwd->listen_port, 556 (fwd->connect_path != NULL) ? fwd->connect_path : 557 fwd->connect_host, fwd->connect_port); 558 break; 559 default: 560 fatal_f("unknown forward type %u", ftype); 561 } 562 return ret; 563} 564 565static int 566compare_host(const char *a, const char *b) 567{ 568 if (a == NULL && b == NULL) 569 return 1; 570 if (a == NULL || b == NULL) 571 return 0; 572 return strcmp(a, b) == 0; 573} 574 575static int 576compare_forward(struct Forward *a, struct Forward *b) 577{ 578 if (!compare_host(a->listen_host, b->listen_host)) 579 return 0; 580 if (!compare_host(a->listen_path, b->listen_path)) 581 return 0; 582 if (a->listen_port != b->listen_port) 583 return 0; 584 if (!compare_host(a->connect_host, b->connect_host)) 585 return 0; 586 if (!compare_host(a->connect_path, b->connect_path)) 587 return 0; 588 if (a->connect_port != b->connect_port) 589 return 0; 590 591 return 1; 592} 593 594static void 595mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) 596{ 597 struct mux_channel_confirm_ctx *fctx = ctxt; 598 char *failmsg = NULL; 599 struct Forward *rfwd; 600 Channel *c; 601 struct sshbuf *out; 602 u_int port; 603 int r; 604 605 if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { 606 /* no channel for reply */ 607 error_f("unknown channel"); 608 return; 609 } 610 if ((out = sshbuf_new()) == NULL) 611 fatal_f("sshbuf_new"); 612 if (fctx->fid >= options.num_remote_forwards || 613 (options.remote_forwards[fctx->fid].connect_path == NULL && 614 options.remote_forwards[fctx->fid].connect_host == NULL)) { 615 xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); 616 goto fail; 617 } 618 rfwd = &options.remote_forwards[fctx->fid]; 619 debug_f("%s for: listen %d, connect %s:%d", 620 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 621 rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : 622 rfwd->connect_host, rfwd->connect_port); 623 if (type == SSH2_MSG_REQUEST_SUCCESS) { 624 if (rfwd->listen_port == 0) { 625 if ((r = sshpkt_get_u32(ssh, &port)) != 0) 626 fatal_fr(r, "parse port"); 627 if (port > 65535) { 628 fatal("Invalid allocated port %u for " 629 "mux remote forward to %s:%d", port, 630 rfwd->connect_host, rfwd->connect_port); 631 } 632 rfwd->allocated_port = (int)port; 633 debug("Allocated port %u for mux remote forward" 634 " to %s:%d", rfwd->allocated_port, 635 rfwd->connect_host, rfwd->connect_port); 636 if ((r = sshbuf_put_u32(out, 637 MUX_S_REMOTE_PORT)) != 0 || 638 (r = sshbuf_put_u32(out, fctx->rid)) != 0 || 639 (r = sshbuf_put_u32(out, 640 rfwd->allocated_port)) != 0) 641 fatal_fr(r, "reply"); 642 channel_update_permission(ssh, rfwd->handle, 643 rfwd->allocated_port); 644 } else { 645 reply_ok(out, fctx->rid); 646 } 647 goto out; 648 } else { 649 if (rfwd->listen_port == 0) 650 channel_update_permission(ssh, rfwd->handle, -1); 651 if (rfwd->listen_path != NULL) 652 xasprintf(&failmsg, "remote port forwarding failed for " 653 "listen path %s", rfwd->listen_path); 654 else 655 xasprintf(&failmsg, "remote port forwarding failed for " 656 "listen port %d", rfwd->listen_port); 657 658 debug2_f("clearing registered forwarding for listen %d, " 659 "connect %s:%d", rfwd->listen_port, 660 rfwd->connect_path ? rfwd->connect_path : 661 rfwd->connect_host, rfwd->connect_port); 662 663 free(rfwd->listen_host); 664 free(rfwd->listen_path); 665 free(rfwd->connect_host); 666 free(rfwd->connect_path); 667 memset(rfwd, 0, sizeof(*rfwd)); 668 } 669 fail: 670 error_f("%s", failmsg); 671 reply_error(out, MUX_S_FAILURE, fctx->rid, failmsg); 672 free(failmsg); 673 out: 674 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 675 fatal_fr(r, "enqueue"); 676 sshbuf_free(out); 677 if (c->mux_pause <= 0) 678 fatal_f("mux_pause %d", c->mux_pause); 679 c->mux_pause = 0; /* start processing messages again */ 680} 681 682static int 683mux_master_process_open_fwd(struct ssh *ssh, u_int rid, 684 Channel *c, struct sshbuf *m, struct sshbuf *reply) 685{ 686 struct Forward fwd; 687 char *fwd_desc = NULL; 688 char *listen_addr, *connect_addr; 689 u_int ftype; 690 u_int lport, cport; 691 int r, i, ret = 0, freefwd = 1; 692 693 memset(&fwd, 0, sizeof(fwd)); 694 695 /* XXX - lport/cport check redundant */ 696 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 697 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 698 (r = sshbuf_get_u32(m, &lport)) != 0 || 699 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 700 (r = sshbuf_get_u32(m, &cport)) != 0 || 701 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 702 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 703 error_f("malformed message"); 704 ret = -1; 705 goto out; 706 } 707 if (*listen_addr == '\0') { 708 free(listen_addr); 709 listen_addr = NULL; 710 } 711 if (*connect_addr == '\0') { 712 free(connect_addr); 713 connect_addr = NULL; 714 } 715 716 memset(&fwd, 0, sizeof(fwd)); 717 fwd.listen_port = lport; 718 if (fwd.listen_port == PORT_STREAMLOCAL) 719 fwd.listen_path = listen_addr; 720 else 721 fwd.listen_host = listen_addr; 722 fwd.connect_port = cport; 723 if (fwd.connect_port == PORT_STREAMLOCAL) 724 fwd.connect_path = connect_addr; 725 else 726 fwd.connect_host = connect_addr; 727 728 debug2_f("channel %d: request %s", c->self, 729 (fwd_desc = format_forward(ftype, &fwd))); 730 731 if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && 732 ftype != MUX_FWD_DYNAMIC) { 733 logit_f("invalid forwarding type %u", ftype); 734 invalid: 735 free(listen_addr); 736 free(connect_addr); 737 reply_error(reply, MUX_S_FAILURE, rid, 738 "Invalid forwarding request"); 739 return 0; 740 } 741 if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { 742 logit_f("streamlocal and dynamic forwards " 743 "are mutually exclusive"); 744 goto invalid; 745 } 746 if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { 747 logit_f("invalid listen port %u", fwd.listen_port); 748 goto invalid; 749 } 750 if ((fwd.connect_port != PORT_STREAMLOCAL && 751 fwd.connect_port >= 65536) || 752 (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && 753 fwd.connect_port == 0)) { 754 logit_f("invalid connect port %u", 755 fwd.connect_port); 756 goto invalid; 757 } 758 if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && 759 fwd.connect_path == NULL) { 760 logit_f("missing connect host"); 761 goto invalid; 762 } 763 764 /* Skip forwards that have already been requested */ 765 switch (ftype) { 766 case MUX_FWD_LOCAL: 767 case MUX_FWD_DYNAMIC: 768 for (i = 0; i < options.num_local_forwards; i++) { 769 if (compare_forward(&fwd, 770 options.local_forwards + i)) { 771 exists: 772 debug2_f("found existing forwarding"); 773 reply_ok(reply, rid); 774 goto out; 775 } 776 } 777 break; 778 case MUX_FWD_REMOTE: 779 for (i = 0; i < options.num_remote_forwards; i++) { 780 if (!compare_forward(&fwd, options.remote_forwards + i)) 781 continue; 782 if (fwd.listen_port != 0) 783 goto exists; 784 debug2_f("found allocated port"); 785 if ((r = sshbuf_put_u32(reply, 786 MUX_S_REMOTE_PORT)) != 0 || 787 (r = sshbuf_put_u32(reply, rid)) != 0 || 788 (r = sshbuf_put_u32(reply, 789 options.remote_forwards[i].allocated_port)) != 0) 790 fatal_fr(r, "reply FWD_REMOTE"); 791 goto out; 792 } 793 break; 794 } 795 796 if (options.control_master == SSHCTL_MASTER_ASK || 797 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 798 if (!ask_permission("Open %s on %s?", fwd_desc, host)) { 799 debug2_f("forwarding refused by user"); 800 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 801 "Permission denied"); 802 goto out; 803 } 804 } 805 806 if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { 807 if (!channel_setup_local_fwd_listener(ssh, &fwd, 808 &options.fwd_opts)) { 809 fail: 810 logit_f("requested %s failed", fwd_desc); 811 reply_error(reply, MUX_S_FAILURE, rid, 812 "Port forwarding failed"); 813 goto out; 814 } 815 add_local_forward(&options, &fwd); 816 freefwd = 0; 817 } else { 818 struct mux_channel_confirm_ctx *fctx; 819 820 fwd.handle = channel_request_remote_forwarding(ssh, &fwd); 821 if (fwd.handle < 0) 822 goto fail; 823 add_remote_forward(&options, &fwd); 824 fctx = xcalloc(1, sizeof(*fctx)); 825 fctx->cid = c->self; 826 fctx->rid = rid; 827 fctx->fid = options.num_remote_forwards - 1; 828 client_register_global_confirm(mux_confirm_remote_forward, 829 fctx); 830 freefwd = 0; 831 c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ 832 /* delayed reply in mux_confirm_remote_forward */ 833 goto out; 834 } 835 reply_ok(reply, rid); 836 out: 837 free(fwd_desc); 838 if (freefwd) { 839 free(fwd.listen_host); 840 free(fwd.listen_path); 841 free(fwd.connect_host); 842 free(fwd.connect_path); 843 } 844 return ret; 845} 846 847static int 848mux_master_process_close_fwd(struct ssh *ssh, u_int rid, 849 Channel *c, struct sshbuf *m, struct sshbuf *reply) 850{ 851 struct Forward fwd, *found_fwd; 852 char *fwd_desc = NULL; 853 const char *error_reason = NULL; 854 char *listen_addr = NULL, *connect_addr = NULL; 855 u_int ftype; 856 int r, i, ret = 0; 857 u_int lport, cport; 858 859 memset(&fwd, 0, sizeof(fwd)); 860 861 if ((r = sshbuf_get_u32(m, &ftype)) != 0 || 862 (r = sshbuf_get_cstring(m, &listen_addr, NULL)) != 0 || 863 (r = sshbuf_get_u32(m, &lport)) != 0 || 864 (r = sshbuf_get_cstring(m, &connect_addr, NULL)) != 0 || 865 (r = sshbuf_get_u32(m, &cport)) != 0 || 866 (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || 867 (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { 868 error_f("malformed message"); 869 ret = -1; 870 goto out; 871 } 872 873 if (*listen_addr == '\0') { 874 free(listen_addr); 875 listen_addr = NULL; 876 } 877 if (*connect_addr == '\0') { 878 free(connect_addr); 879 connect_addr = NULL; 880 } 881 882 memset(&fwd, 0, sizeof(fwd)); 883 fwd.listen_port = lport; 884 if (fwd.listen_port == PORT_STREAMLOCAL) 885 fwd.listen_path = listen_addr; 886 else 887 fwd.listen_host = listen_addr; 888 fwd.connect_port = cport; 889 if (fwd.connect_port == PORT_STREAMLOCAL) 890 fwd.connect_path = connect_addr; 891 else 892 fwd.connect_host = connect_addr; 893 894 debug2_f("channel %d: request cancel %s", c->self, 895 (fwd_desc = format_forward(ftype, &fwd))); 896 897 /* make sure this has been requested */ 898 found_fwd = NULL; 899 switch (ftype) { 900 case MUX_FWD_LOCAL: 901 case MUX_FWD_DYNAMIC: 902 for (i = 0; i < options.num_local_forwards; i++) { 903 if (compare_forward(&fwd, 904 options.local_forwards + i)) { 905 found_fwd = options.local_forwards + i; 906 break; 907 } 908 } 909 break; 910 case MUX_FWD_REMOTE: 911 for (i = 0; i < options.num_remote_forwards; i++) { 912 if (compare_forward(&fwd, 913 options.remote_forwards + i)) { 914 found_fwd = options.remote_forwards + i; 915 break; 916 } 917 } 918 break; 919 } 920 921 if (found_fwd == NULL) 922 error_reason = "port not forwarded"; 923 else if (ftype == MUX_FWD_REMOTE) { 924 /* 925 * This shouldn't fail unless we confused the host/port 926 * between options.remote_forwards and permitted_opens. 927 * However, for dynamic allocated listen ports we need 928 * to use the actual listen port. 929 */ 930 if (channel_request_rforward_cancel(ssh, found_fwd) == -1) 931 error_reason = "port not in permitted opens"; 932 } else { /* local and dynamic forwards */ 933 /* Ditto */ 934 if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, 935 &options.fwd_opts) == -1) 936 error_reason = "port not found"; 937 } 938 939 if (error_reason != NULL) 940 reply_error(reply, MUX_S_FAILURE, rid, error_reason); 941 else { 942 reply_ok(reply, rid); 943 free(found_fwd->listen_host); 944 free(found_fwd->listen_path); 945 free(found_fwd->connect_host); 946 free(found_fwd->connect_path); 947 found_fwd->listen_host = found_fwd->connect_host = NULL; 948 found_fwd->listen_path = found_fwd->connect_path = NULL; 949 found_fwd->listen_port = found_fwd->connect_port = 0; 950 } 951 out: 952 free(fwd_desc); 953 free(listen_addr); 954 free(connect_addr); 955 956 return ret; 957} 958 959static int 960mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid, 961 Channel *c, struct sshbuf *m, struct sshbuf *reply) 962{ 963 Channel *nc; 964 char *chost = NULL; 965 u_int cport, i, j; 966 int r, new_fd[2]; 967 struct mux_stdio_confirm_ctx *cctx; 968 969 if ((r = sshbuf_skip_string(m)) != 0 || /* reserved */ 970 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 971 (r = sshbuf_get_u32(m, &cport)) != 0) { 972 free(chost); 973 error_f("malformed message"); 974 return -1; 975 } 976 977 debug2_f("channel %d: stdio fwd to %s:%u", c->self, chost, cport); 978 979 /* Gather fds from client */ 980 for(i = 0; i < 2; i++) { 981 if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { 982 error_f("failed to receive fd %d from client", i); 983 for (j = 0; j < i; j++) 984 close(new_fd[j]); 985 free(chost); 986 987 /* prepare reply */ 988 reply_error(reply, MUX_S_FAILURE, rid, 989 "did not receive file descriptors"); 990 return -1; 991 } 992 } 993 994 debug3_f("got fds stdin %d, stdout %d", new_fd[0], new_fd[1]); 995 996 /* XXX support multiple child sessions in future */ 997 if (c->have_remote_id) { 998 debug2_f("session already open"); 999 reply_error(reply, MUX_S_FAILURE, rid, 1000 "Multiple sessions not supported"); 1001 cleanup: 1002 close(new_fd[0]); 1003 close(new_fd[1]); 1004 free(chost); 1005 return 0; 1006 } 1007 1008 if (options.control_master == SSHCTL_MASTER_ASK || 1009 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1010 if (!ask_permission("Allow forward to %s:%u? ", 1011 chost, cport)) { 1012 debug2_f("stdio fwd refused by user"); 1013 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1014 "Permission denied"); 1015 goto cleanup; 1016 } 1017 } 1018 1019 /* enable nonblocking unless tty */ 1020 if (!isatty(new_fd[0])) 1021 set_nonblock(new_fd[0]); 1022 if (!isatty(new_fd[1])) 1023 set_nonblock(new_fd[1]); 1024 1025 nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]); 1026 free(chost); 1027 1028 nc->ctl_chan = c->self; /* link session -> control channel */ 1029 c->remote_id = nc->self; /* link control -> session channel */ 1030 c->have_remote_id = 1; 1031 1032 debug2_f("channel_new: %d control %d", nc->self, nc->ctl_chan); 1033 1034 channel_register_cleanup(ssh, nc->self, 1035 mux_master_session_cleanup_cb, 1); 1036 1037 cctx = xcalloc(1, sizeof(*cctx)); 1038 cctx->rid = rid; 1039 channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); 1040 c->mux_pause = 1; /* stop handling messages until open_confirm done */ 1041 1042 /* reply is deferred, sent by mux_session_confirm */ 1043 return 0; 1044} 1045 1046/* Callback on open confirmation in mux master for a mux stdio fwd session. */ 1047static void 1048mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) 1049{ 1050 struct mux_stdio_confirm_ctx *cctx = arg; 1051 Channel *c, *cc; 1052 struct sshbuf *reply; 1053 int r; 1054 1055 if (cctx == NULL) 1056 fatal_f("cctx == NULL"); 1057 if ((c = channel_by_id(ssh, id)) == NULL) 1058 fatal_f("no channel for id %d", id); 1059 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1060 fatal_f("channel %d lacks control channel %d", 1061 id, c->ctl_chan); 1062 if ((reply = sshbuf_new()) == NULL) 1063 fatal_f("sshbuf_new"); 1064 1065 if (!success) { 1066 debug3_f("sending failure reply"); 1067 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1068 "Session open refused by peer"); 1069 /* prepare reply */ 1070 goto done; 1071 } 1072 1073 debug3_f("sending success reply"); 1074 /* prepare reply */ 1075 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1076 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1077 (r = sshbuf_put_u32(reply, c->self)) != 0) 1078 fatal_fr(r, "reply"); 1079 1080 done: 1081 /* Send reply */ 1082 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1083 fatal_fr(r, "enqueue"); 1084 sshbuf_free(reply); 1085 1086 if (cc->mux_pause <= 0) 1087 fatal_f("mux_pause %d", cc->mux_pause); 1088 cc->mux_pause = 0; /* start processing messages again */ 1089 c->open_confirm_ctx = NULL; 1090 free(cctx); 1091} 1092 1093static int 1094mux_master_process_stop_listening(struct ssh *ssh, u_int rid, 1095 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1096{ 1097 debug_f("channel %d: stop listening", c->self); 1098 1099 if (options.control_master == SSHCTL_MASTER_ASK || 1100 options.control_master == SSHCTL_MASTER_AUTO_ASK) { 1101 if (!ask_permission("Disable further multiplexing on shared " 1102 "connection to %s? ", host)) { 1103 debug2_f("stop listen refused by user"); 1104 reply_error(reply, MUX_S_PERMISSION_DENIED, rid, 1105 "Permission denied"); 1106 return 0; 1107 } 1108 } 1109 1110 if (mux_listener_channel != NULL) { 1111 channel_free(ssh, mux_listener_channel); 1112 client_stop_mux(); 1113 free(options.control_path); 1114 options.control_path = NULL; 1115 mux_listener_channel = NULL; 1116 muxserver_sock = -1; 1117 } 1118 1119 reply_ok(reply, rid); 1120 return 0; 1121} 1122 1123static int 1124mux_master_process_proxy(struct ssh *ssh, u_int rid, 1125 Channel *c, struct sshbuf *m, struct sshbuf *reply) 1126{ 1127 int r; 1128 1129 debug_f("channel %d: proxy request", c->self); 1130 1131 c->mux_rcb = channel_proxy_downstream; 1132 if ((r = sshbuf_put_u32(reply, MUX_S_PROXY)) != 0 || 1133 (r = sshbuf_put_u32(reply, rid)) != 0) 1134 fatal_fr(r, "reply"); 1135 1136 return 0; 1137} 1138 1139/* Channel callbacks fired on read/write from mux client fd */ 1140static int 1141mux_master_read_cb(struct ssh *ssh, Channel *c) 1142{ 1143 struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; 1144 struct sshbuf *in = NULL, *out = NULL; 1145 u_int type, rid, i; 1146 int r, ret = -1; 1147 1148 if ((out = sshbuf_new()) == NULL) 1149 fatal_f("sshbuf_new"); 1150 1151 /* Setup ctx and */ 1152 if (c->mux_ctx == NULL) { 1153 state = xcalloc(1, sizeof(*state)); 1154 c->mux_ctx = state; 1155 channel_register_cleanup(ssh, c->self, 1156 mux_master_control_cleanup_cb, 0); 1157 1158 /* Send hello */ 1159 if ((r = sshbuf_put_u32(out, MUX_MSG_HELLO)) != 0 || 1160 (r = sshbuf_put_u32(out, SSHMUX_VER)) != 0) 1161 fatal_fr(r, "reply"); 1162 /* no extensions */ 1163 if ((r = sshbuf_put_stringb(c->output, out)) != 0) 1164 fatal_fr(r, "enqueue"); 1165 debug3_f("channel %d: hello sent", c->self); 1166 ret = 0; 1167 goto out; 1168 } 1169 1170 /* Channel code ensures that we receive whole packets */ 1171 if ((r = sshbuf_froms(c->input, &in)) != 0) { 1172 malf: 1173 error_f("malformed message"); 1174 goto out; 1175 } 1176 1177 if ((r = sshbuf_get_u32(in, &type)) != 0) 1178 goto malf; 1179 debug3_f("channel %d packet type 0x%08x len %zu", c->self, 1180 type, sshbuf_len(in)); 1181 1182 if (type == MUX_MSG_HELLO) 1183 rid = 0; 1184 else { 1185 if (!state->hello_rcvd) { 1186 error_f("expected MUX_MSG_HELLO(0x%08x), " 1187 "received 0x%08x", MUX_MSG_HELLO, type); 1188 goto out; 1189 } 1190 if ((r = sshbuf_get_u32(in, &rid)) != 0) 1191 goto malf; 1192 } 1193 1194 for (i = 0; mux_master_handlers[i].handler != NULL; i++) { 1195 if (type == mux_master_handlers[i].type) { 1196 ret = mux_master_handlers[i].handler(ssh, rid, 1197 c, in, out); 1198 break; 1199 } 1200 } 1201 if (mux_master_handlers[i].handler == NULL) { 1202 error_f("unsupported mux message 0x%08x", type); 1203 reply_error(out, MUX_S_FAILURE, rid, "unsupported request"); 1204 ret = 0; 1205 } 1206 /* Enqueue reply packet */ 1207 if (sshbuf_len(out) != 0 && 1208 (r = sshbuf_put_stringb(c->output, out)) != 0) 1209 fatal_fr(r, "enqueue"); 1210 out: 1211 sshbuf_free(in); 1212 sshbuf_free(out); 1213 return ret; 1214} 1215 1216void 1217mux_exit_message(struct ssh *ssh, Channel *c, int exitval) 1218{ 1219 struct sshbuf *m; 1220 Channel *mux_chan; 1221 int r; 1222 1223 debug3_f("channel %d: exit message, exitval %d", c->self, exitval); 1224 1225 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1226 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1227 1228 /* Append exit message packet to control socket output queue */ 1229 if ((m = sshbuf_new()) == NULL) 1230 fatal_f("sshbuf_new"); 1231 if ((r = sshbuf_put_u32(m, MUX_S_EXIT_MESSAGE)) != 0 || 1232 (r = sshbuf_put_u32(m, c->self)) != 0 || 1233 (r = sshbuf_put_u32(m, exitval)) != 0 || 1234 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1235 fatal_fr(r, "reply"); 1236 sshbuf_free(m); 1237} 1238 1239void 1240mux_tty_alloc_failed(struct ssh *ssh, Channel *c) 1241{ 1242 struct sshbuf *m; 1243 Channel *mux_chan; 1244 int r; 1245 1246 debug3_f("channel %d: TTY alloc failed", c->self); 1247 1248 if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) 1249 fatal_f("channel %d missing mux %d", c->self, c->ctl_chan); 1250 1251 /* Append exit message packet to control socket output queue */ 1252 if ((m = sshbuf_new()) == NULL) 1253 fatal_f("sshbuf_new"); 1254 if ((r = sshbuf_put_u32(m, MUX_S_TTY_ALLOC_FAIL)) != 0 || 1255 (r = sshbuf_put_u32(m, c->self)) != 0 || 1256 (r = sshbuf_put_stringb(mux_chan->output, m)) != 0) 1257 fatal_fr(r, "reply"); 1258 sshbuf_free(m); 1259} 1260 1261/* Prepare a mux master to listen on a Unix domain socket. */ 1262void 1263muxserver_listen(struct ssh *ssh) 1264{ 1265 mode_t old_umask; 1266 char *orig_control_path = options.control_path; 1267 char rbuf[16+1]; 1268 u_int i, r; 1269 int oerrno; 1270 1271 if (options.control_path == NULL || 1272 options.control_master == SSHCTL_MASTER_NO) 1273 return; 1274 1275 debug("setting up multiplex master socket"); 1276 1277 /* 1278 * Use a temporary path before listen so we can pseudo-atomically 1279 * establish the listening socket in its final location to avoid 1280 * other processes racing in between bind() and listen() and hitting 1281 * an unready socket. 1282 */ 1283 for (i = 0; i < sizeof(rbuf) - 1; i++) { 1284 r = arc4random_uniform(26+26+10); 1285 rbuf[i] = (r < 26) ? 'a' + r : 1286 (r < 26*2) ? 'A' + r - 26 : 1287 '0' + r - 26 - 26; 1288 } 1289 rbuf[sizeof(rbuf) - 1] = '\0'; 1290 options.control_path = NULL; 1291 xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); 1292 debug3_f("temporary control path %s", options.control_path); 1293 1294 old_umask = umask(0177); 1295 muxserver_sock = unix_listener(options.control_path, 64, 0); 1296 oerrno = errno; 1297 umask(old_umask); 1298 if (muxserver_sock < 0) { 1299 if (oerrno == EINVAL || oerrno == EADDRINUSE) { 1300 error("ControlSocket %s already exists, " 1301 "disabling multiplexing", options.control_path); 1302 disable_mux_master: 1303 if (muxserver_sock != -1) { 1304 close(muxserver_sock); 1305 muxserver_sock = -1; 1306 } 1307 free(orig_control_path); 1308 free(options.control_path); 1309 options.control_path = NULL; 1310 options.control_master = SSHCTL_MASTER_NO; 1311 return; 1312 } else { 1313 /* unix_listener() logs the error */ 1314 cleanup_exit(254); 1315 } 1316 } 1317 1318 /* Now atomically "move" the mux socket into position */ 1319 if (link(options.control_path, orig_control_path) != 0) { 1320 if (errno != EEXIST) { 1321 fatal_f("link mux listener %s => %s: %s", 1322 options.control_path, orig_control_path, 1323 strerror(errno)); 1324 } 1325 error("ControlSocket %s already exists, disabling multiplexing", 1326 orig_control_path); 1327 unlink(options.control_path); 1328 goto disable_mux_master; 1329 } 1330 unlink(options.control_path); 1331 free(options.control_path); 1332 options.control_path = orig_control_path; 1333 1334 set_nonblock(muxserver_sock); 1335 1336 mux_listener_channel = channel_new(ssh, "mux listener", 1337 SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, 1338 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 1339 0, options.control_path, 1); 1340 mux_listener_channel->mux_rcb = mux_master_read_cb; 1341 debug3_f("mux listener channel %d fd %d", 1342 mux_listener_channel->self, mux_listener_channel->sock); 1343} 1344 1345/* Callback on open confirmation in mux master for a mux client session. */ 1346static void 1347mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) 1348{ 1349 struct mux_session_confirm_ctx *cctx = arg; 1350 const char *display; 1351 Channel *c, *cc; 1352 int i, r; 1353 struct sshbuf *reply; 1354 1355 if (cctx == NULL) 1356 fatal_f("cctx == NULL"); 1357 if ((c = channel_by_id(ssh, id)) == NULL) 1358 fatal_f("no channel for id %d", id); 1359 if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) 1360 fatal_f("channel %d lacks control channel %d", 1361 id, c->ctl_chan); 1362 if ((reply = sshbuf_new()) == NULL) 1363 fatal_f("sshbuf_new"); 1364 1365 if (!success) { 1366 debug3_f("sending failure reply"); 1367 reply_error(reply, MUX_S_FAILURE, cctx->rid, 1368 "Session open refused by peer"); 1369 goto done; 1370 } 1371 1372 display = getenv("DISPLAY"); 1373 if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { 1374 char *proto, *data; 1375 1376 /* Get reasonable local authentication information. */ 1377 if (client_x11_get_proto(ssh, display, options.xauth_location, 1378 options.forward_x11_trusted, options.forward_x11_timeout, 1379 &proto, &data) == 0) { 1380 /* Request forwarding with authentication spoofing. */ 1381 debug("Requesting X11 forwarding with authentication " 1382 "spoofing."); 1383 x11_request_forwarding_with_spoofing(ssh, id, 1384 display, proto, data, 1); 1385 /* XXX exit_on_forward_failure */ 1386 client_expect_confirm(ssh, id, "X11 forwarding", 1387 CONFIRM_WARN); 1388 } 1389 } 1390 1391 if (cctx->want_agent_fwd && options.forward_agent) { 1392 debug("Requesting authentication agent forwarding."); 1393 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); 1394 if ((r = sshpkt_send(ssh)) != 0) 1395 fatal_fr(r, "send"); 1396 } 1397 1398 client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, 1399 cctx->term, &cctx->tio, c->rfd, cctx->cmd, cctx->env); 1400 1401 debug3_f("sending success reply"); 1402 /* prepare reply */ 1403 if ((r = sshbuf_put_u32(reply, MUX_S_SESSION_OPENED)) != 0 || 1404 (r = sshbuf_put_u32(reply, cctx->rid)) != 0 || 1405 (r = sshbuf_put_u32(reply, c->self)) != 0) 1406 fatal_fr(r, "reply"); 1407 1408 done: 1409 /* Send reply */ 1410 if ((r = sshbuf_put_stringb(cc->output, reply)) != 0) 1411 fatal_fr(r, "enqueue"); 1412 sshbuf_free(reply); 1413 1414 if (cc->mux_pause <= 0) 1415 fatal_f("mux_pause %d", cc->mux_pause); 1416 cc->mux_pause = 0; /* start processing messages again */ 1417 c->open_confirm_ctx = NULL; 1418 sshbuf_free(cctx->cmd); 1419 free(cctx->term); 1420 if (cctx->env != NULL) { 1421 for (i = 0; cctx->env[i] != NULL; i++) 1422 free(cctx->env[i]); 1423 free(cctx->env); 1424 } 1425 free(cctx); 1426} 1427 1428/* ** Multiplexing client support */ 1429 1430/* Exit signal handler */ 1431static void 1432control_client_sighandler(int signo) 1433{ 1434 muxclient_terminate = signo; 1435} 1436 1437/* 1438 * Relay signal handler - used to pass some signals from mux client to 1439 * mux master. 1440 */ 1441static void 1442control_client_sigrelay(int signo) 1443{ 1444 int save_errno = errno; 1445 1446 if (muxserver_pid > 1) 1447 kill(muxserver_pid, signo); 1448 1449 errno = save_errno; 1450} 1451 1452static int 1453mux_client_read(int fd, struct sshbuf *b, size_t need) 1454{ 1455 size_t have; 1456 ssize_t len; 1457 u_char *p; 1458 struct pollfd pfd; 1459 int r; 1460 1461 pfd.fd = fd; 1462 pfd.events = POLLIN; 1463 if ((r = sshbuf_reserve(b, need, &p)) != 0) 1464 fatal_fr(r, "reserve"); 1465 for (have = 0; have < need; ) { 1466 if (muxclient_terminate) { 1467 errno = EINTR; 1468 return -1; 1469 } 1470 len = read(fd, p + have, need - have); 1471 if (len == -1) { 1472 switch (errno) { 1473 case EAGAIN: 1474 (void)poll(&pfd, 1, -1); 1475 /* FALLTHROUGH */ 1476 case EINTR: 1477 continue; 1478 default: 1479 return -1; 1480 } 1481 } 1482 if (len == 0) { 1483 errno = EPIPE; 1484 return -1; 1485 } 1486 have += (size_t)len; 1487 } 1488 return 0; 1489} 1490 1491static int 1492mux_client_write_packet(int fd, struct sshbuf *m) 1493{ 1494 struct sshbuf *queue; 1495 u_int have, need; 1496 int r, oerrno, len; 1497 const u_char *ptr; 1498 struct pollfd pfd; 1499 1500 pfd.fd = fd; 1501 pfd.events = POLLOUT; 1502 if ((queue = sshbuf_new()) == NULL) 1503 fatal_f("sshbuf_new"); 1504 if ((r = sshbuf_put_stringb(queue, m)) != 0) 1505 fatal_fr(r, "enqueue"); 1506 1507 need = sshbuf_len(queue); 1508 ptr = sshbuf_ptr(queue); 1509 1510 for (have = 0; have < need; ) { 1511 if (muxclient_terminate) { 1512 sshbuf_free(queue); 1513 errno = EINTR; 1514 return -1; 1515 } 1516 len = write(fd, ptr + have, need - have); 1517 if (len == -1) { 1518 switch (errno) { 1519 case EAGAIN: 1520 (void)poll(&pfd, 1, -1); 1521 /* FALLTHROUGH */ 1522 case EINTR: 1523 continue; 1524 default: 1525 oerrno = errno; 1526 sshbuf_free(queue); 1527 errno = oerrno; 1528 return -1; 1529 } 1530 } 1531 if (len == 0) { 1532 sshbuf_free(queue); 1533 errno = EPIPE; 1534 return -1; 1535 } 1536 have += (u_int)len; 1537 } 1538 sshbuf_free(queue); 1539 return 0; 1540} 1541 1542static int 1543mux_client_read_packet(int fd, struct sshbuf *m) 1544{ 1545 struct sshbuf *queue; 1546 size_t need, have; 1547 const u_char *ptr; 1548 int r, oerrno; 1549 1550 if ((queue = sshbuf_new()) == NULL) 1551 fatal_f("sshbuf_new"); 1552 if (mux_client_read(fd, queue, 4) != 0) { 1553 if ((oerrno = errno) == EPIPE) 1554 debug3_f("read header failed: %s", 1555 strerror(errno)); 1556 sshbuf_free(queue); 1557 errno = oerrno; 1558 return -1; 1559 } 1560 need = PEEK_U32(sshbuf_ptr(queue)); 1561 if (mux_client_read(fd, queue, need) != 0) { 1562 oerrno = errno; 1563 debug3_f("read body failed: %s", strerror(errno)); 1564 sshbuf_free(queue); 1565 errno = oerrno; 1566 return -1; 1567 } 1568 if ((r = sshbuf_get_string_direct(queue, &ptr, &have)) != 0 || 1569 (r = sshbuf_put(m, ptr, have)) != 0) 1570 fatal_fr(r, "dequeue"); 1571 sshbuf_free(queue); 1572 return 0; 1573} 1574 1575static int 1576mux_client_hello_exchange(int fd) 1577{ 1578 struct sshbuf *m; 1579 u_int type, ver; 1580 int r, ret = -1; 1581 1582 if ((m = sshbuf_new()) == NULL) 1583 fatal_f("sshbuf_new"); 1584 if ((r = sshbuf_put_u32(m, MUX_MSG_HELLO)) != 0 || 1585 (r = sshbuf_put_u32(m, SSHMUX_VER)) != 0) 1586 fatal_fr(r, "assemble hello"); 1587 /* no extensions */ 1588 1589 if (mux_client_write_packet(fd, m) != 0) { 1590 debug_f("write packet: %s", strerror(errno)); 1591 goto out; 1592 } 1593 1594 sshbuf_reset(m); 1595 1596 /* Read their HELLO */ 1597 if (mux_client_read_packet(fd, m) != 0) { 1598 debug_f("read packet failed"); 1599 goto out; 1600 } 1601 1602 if ((r = sshbuf_get_u32(m, &type)) != 0) 1603 fatal_fr(r, "parse type"); 1604 if (type != MUX_MSG_HELLO) { 1605 error_f("expected HELLO (%u) got %u", MUX_MSG_HELLO, type); 1606 goto out; 1607 } 1608 if ((r = sshbuf_get_u32(m, &ver)) != 0) 1609 fatal_fr(r, "parse version"); 1610 if (ver != SSHMUX_VER) { 1611 error("Unsupported multiplexing protocol version %d " 1612 "(expected %d)", ver, SSHMUX_VER); 1613 goto out; 1614 } 1615 debug2_f("master version %u", ver); 1616 /* No extensions are presently defined */ 1617 while (sshbuf_len(m) > 0) { 1618 char *name = NULL; 1619 1620 if ((r = sshbuf_get_cstring(m, &name, NULL)) != 0 || 1621 (r = sshbuf_skip_string(m)) != 0) { /* value */ 1622 error_fr(r, "parse extension"); 1623 goto out; 1624 } 1625 debug2("Unrecognised master extension \"%s\"", name); 1626 free(name); 1627 } 1628 /* success */ 1629 ret = 0; 1630 out: 1631 sshbuf_free(m); 1632 return ret; 1633} 1634 1635static u_int 1636mux_client_request_alive(int fd) 1637{ 1638 struct sshbuf *m; 1639 char *e; 1640 u_int pid, type, rid; 1641 int r; 1642 1643 debug3_f("entering"); 1644 1645 if ((m = sshbuf_new()) == NULL) 1646 fatal_f("sshbuf_new"); 1647 if ((r = sshbuf_put_u32(m, MUX_C_ALIVE_CHECK)) != 0 || 1648 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1649 fatal_fr(r, "assemble"); 1650 1651 if (mux_client_write_packet(fd, m) != 0) 1652 fatal_f("write packet: %s", strerror(errno)); 1653 1654 sshbuf_reset(m); 1655 1656 /* Read their reply */ 1657 if (mux_client_read_packet(fd, m) != 0) { 1658 sshbuf_free(m); 1659 return 0; 1660 } 1661 1662 if ((r = sshbuf_get_u32(m, &type)) != 0) 1663 fatal_fr(r, "parse type"); 1664 if (type != MUX_S_ALIVE) { 1665 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1666 fatal_fr(r, "parse error message"); 1667 fatal_f("master returned error: %s", e); 1668 } 1669 1670 if ((r = sshbuf_get_u32(m, &rid)) != 0) 1671 fatal_fr(r, "parse remote ID"); 1672 if (rid != muxclient_request_id) 1673 fatal_f("out of sequence reply: my id %u theirs %u", 1674 muxclient_request_id, rid); 1675 if ((r = sshbuf_get_u32(m, &pid)) != 0) 1676 fatal_fr(r, "parse PID"); 1677 sshbuf_free(m); 1678 1679 debug3_f("done pid = %u", pid); 1680 1681 muxclient_request_id++; 1682 1683 return pid; 1684} 1685 1686static void 1687mux_client_request_terminate(int fd) 1688{ 1689 struct sshbuf *m; 1690 char *e; 1691 u_int type, rid; 1692 int r; 1693 1694 debug3_f("entering"); 1695 1696 if ((m = sshbuf_new()) == NULL) 1697 fatal_f("sshbuf_new"); 1698 if ((r = sshbuf_put_u32(m, MUX_C_TERMINATE)) != 0 || 1699 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 1700 fatal_fr(r, "request"); 1701 1702 if (mux_client_write_packet(fd, m) != 0) 1703 fatal_f("write packet: %s", strerror(errno)); 1704 1705 sshbuf_reset(m); 1706 1707 /* Read their reply */ 1708 if (mux_client_read_packet(fd, m) != 0) { 1709 /* Remote end exited already */ 1710 if (errno == EPIPE) { 1711 sshbuf_free(m); 1712 return; 1713 } 1714 fatal_f("read from master failed: %s", strerror(errno)); 1715 } 1716 1717 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1718 (r = sshbuf_get_u32(m, &rid)) != 0) 1719 fatal_fr(r, "parse"); 1720 if (rid != muxclient_request_id) 1721 fatal_f("out of sequence reply: my id %u theirs %u", 1722 muxclient_request_id, rid); 1723 switch (type) { 1724 case MUX_S_OK: 1725 break; 1726 case MUX_S_PERMISSION_DENIED: 1727 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1728 fatal_fr(r, "parse error message"); 1729 fatal("Master refused termination request: %s", e); 1730 case MUX_S_FAILURE: 1731 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1732 fatal_fr(r, "parse error message"); 1733 fatal_f("termination request failed: %s", e); 1734 default: 1735 fatal_f("unexpected response from master 0x%08x", type); 1736 } 1737 sshbuf_free(m); 1738 muxclient_request_id++; 1739} 1740 1741static int 1742mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) 1743{ 1744 struct sshbuf *m; 1745 char *e, *fwd_desc; 1746 const char *lhost, *chost; 1747 u_int type, rid; 1748 int r; 1749 1750 fwd_desc = format_forward(ftype, fwd); 1751 debug("Requesting %s %s", 1752 cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); 1753 free(fwd_desc); 1754 1755 type = cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD; 1756 if (fwd->listen_path != NULL) 1757 lhost = fwd->listen_path; 1758 else if (fwd->listen_host == NULL) 1759 lhost = ""; 1760 else if (*fwd->listen_host == '\0') 1761 lhost = "*"; 1762 else 1763 lhost = fwd->listen_host; 1764 1765 if (fwd->connect_path != NULL) 1766 chost = fwd->connect_path; 1767 else if (fwd->connect_host == NULL) 1768 chost = ""; 1769 else 1770 chost = fwd->connect_host; 1771 1772 if ((m = sshbuf_new()) == NULL) 1773 fatal_f("sshbuf_new"); 1774 if ((r = sshbuf_put_u32(m, type)) != 0 || 1775 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1776 (r = sshbuf_put_u32(m, ftype)) != 0 || 1777 (r = sshbuf_put_cstring(m, lhost)) != 0 || 1778 (r = sshbuf_put_u32(m, fwd->listen_port)) != 0 || 1779 (r = sshbuf_put_cstring(m, chost)) != 0 || 1780 (r = sshbuf_put_u32(m, fwd->connect_port)) != 0) 1781 fatal_fr(r, "request"); 1782 1783 if (mux_client_write_packet(fd, m) != 0) 1784 fatal_f("write packet: %s", strerror(errno)); 1785 1786 sshbuf_reset(m); 1787 1788 /* Read their reply */ 1789 if (mux_client_read_packet(fd, m) != 0) { 1790 sshbuf_free(m); 1791 return -1; 1792 } 1793 1794 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1795 (r = sshbuf_get_u32(m, &rid)) != 0) 1796 fatal_fr(r, "parse"); 1797 if (rid != muxclient_request_id) 1798 fatal_f("out of sequence reply: my id %u theirs %u", 1799 muxclient_request_id, rid); 1800 1801 switch (type) { 1802 case MUX_S_OK: 1803 break; 1804 case MUX_S_REMOTE_PORT: 1805 if (cancel_flag) 1806 fatal_f("got MUX_S_REMOTE_PORT for cancel"); 1807 if ((r = sshbuf_get_u32(m, &fwd->allocated_port)) != 0) 1808 fatal_fr(r, "parse port"); 1809 verbose("Allocated port %u for remote forward to %s:%d", 1810 fwd->allocated_port, 1811 fwd->connect_host ? fwd->connect_host : "", 1812 fwd->connect_port); 1813 if (muxclient_command == SSHMUX_COMMAND_FORWARD) 1814 fprintf(stdout, "%i\n", fwd->allocated_port); 1815 break; 1816 case MUX_S_PERMISSION_DENIED: 1817 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1818 fatal_fr(r, "parse error message"); 1819 sshbuf_free(m); 1820 error("Master refused forwarding request: %s", e); 1821 return -1; 1822 case MUX_S_FAILURE: 1823 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1824 fatal_fr(r, "parse error message"); 1825 sshbuf_free(m); 1826 error_f("forwarding request failed: %s", e); 1827 return -1; 1828 default: 1829 fatal_f("unexpected response from master 0x%08x", type); 1830 } 1831 sshbuf_free(m); 1832 1833 muxclient_request_id++; 1834 return 0; 1835} 1836 1837static int 1838mux_client_forwards(int fd, int cancel_flag) 1839{ 1840 int i, ret = 0; 1841 1842 debug3_f("%s forwardings: %d local, %d remote", 1843 cancel_flag ? "cancel" : "request", 1844 options.num_local_forwards, options.num_remote_forwards); 1845 1846 /* XXX ExitOnForwardingFailure */ 1847 for (i = 0; i < options.num_local_forwards; i++) { 1848 if (mux_client_forward(fd, cancel_flag, 1849 options.local_forwards[i].connect_port == 0 ? 1850 MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, 1851 options.local_forwards + i) != 0) 1852 ret = -1; 1853 } 1854 for (i = 0; i < options.num_remote_forwards; i++) { 1855 if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, 1856 options.remote_forwards + i) != 0) 1857 ret = -1; 1858 } 1859 return ret; 1860} 1861 1862static int 1863mux_client_request_session(int fd) 1864{ 1865 struct sshbuf *m; 1866 char *e; 1867 const char *term; 1868 u_int echar, rid, sid, esid, exitval, type, exitval_seen; 1869 extern char **environ; 1870 int r, i, rawmode; 1871 1872 debug3_f("entering"); 1873 1874 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 1875 error_f("master alive request failed"); 1876 return -1; 1877 } 1878 1879 ssh_signal(SIGPIPE, SIG_IGN); 1880 1881 if (stdin_null_flag && stdfd_devnull(1, 0, 0) == -1) 1882 fatal_f("stdfd_devnull failed"); 1883 1884 if ((term = getenv("TERM")) == NULL) 1885 term = ""; 1886 echar = 0xffffffff; 1887 if (options.escape_char != SSH_ESCAPECHAR_NONE) 1888 echar = (u_int)options.escape_char; 1889 1890 if ((m = sshbuf_new()) == NULL) 1891 fatal_f("sshbuf_new"); 1892 if ((r = sshbuf_put_u32(m, MUX_C_NEW_SESSION)) != 0 || 1893 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 1894 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 1895 (r = sshbuf_put_u32(m, tty_flag)) != 0 || 1896 (r = sshbuf_put_u32(m, options.forward_x11)) != 0 || 1897 (r = sshbuf_put_u32(m, options.forward_agent)) != 0 || 1898 (r = sshbuf_put_u32(m, subsystem_flag)) != 0 || 1899 (r = sshbuf_put_u32(m, echar)) != 0 || 1900 (r = sshbuf_put_cstring(m, term)) != 0 || 1901 (r = sshbuf_put_stringb(m, command)) != 0) 1902 fatal_fr(r, "request"); 1903 1904 /* Pass environment */ 1905 if (options.num_send_env > 0 && environ != NULL) { 1906 for (i = 0; environ[i] != NULL; i++) { 1907 if (!env_permitted(environ[i])) 1908 continue; 1909 if ((r = sshbuf_put_cstring(m, environ[i])) != 0) 1910 fatal_fr(r, "request sendenv"); 1911 } 1912 } 1913 for (i = 0; i < options.num_setenv; i++) { 1914 if ((r = sshbuf_put_cstring(m, options.setenv[i])) != 0) 1915 fatal_fr(r, "request setenv"); 1916 } 1917 1918 if (mux_client_write_packet(fd, m) != 0) 1919 fatal_f("write packet: %s", strerror(errno)); 1920 1921 /* Send the stdio file descriptors */ 1922 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 1923 mm_send_fd(fd, STDOUT_FILENO) == -1 || 1924 mm_send_fd(fd, STDERR_FILENO) == -1) 1925 fatal_f("send fds failed"); 1926 1927 debug3_f("session request sent"); 1928 1929 /* Read their reply */ 1930 sshbuf_reset(m); 1931 if (mux_client_read_packet(fd, m) != 0) { 1932 error_f("read from master failed: %s", strerror(errno)); 1933 sshbuf_free(m); 1934 return -1; 1935 } 1936 1937 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1938 (r = sshbuf_get_u32(m, &rid)) != 0) 1939 fatal_fr(r, "parse"); 1940 if (rid != muxclient_request_id) 1941 fatal_f("out of sequence reply: my id %u theirs %u", 1942 muxclient_request_id, rid); 1943 1944 switch (type) { 1945 case MUX_S_SESSION_OPENED: 1946 if ((r = sshbuf_get_u32(m, &sid)) != 0) 1947 fatal_fr(r, "parse session ID"); 1948 debug_f("master session id: %u", sid); 1949 break; 1950 case MUX_S_PERMISSION_DENIED: 1951 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1952 fatal_fr(r, "parse error message"); 1953 error("Master refused session request: %s", e); 1954 sshbuf_free(m); 1955 return -1; 1956 case MUX_S_FAILURE: 1957 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 1958 fatal_fr(r, "parse error message"); 1959 error_f("session request failed: %s", e); 1960 sshbuf_free(m); 1961 return -1; 1962 default: 1963 sshbuf_free(m); 1964 error_f("unexpected response from master 0x%08x", type); 1965 return -1; 1966 } 1967 muxclient_request_id++; 1968 1969#ifdef __OpenBSD__ 1970 if (pledge("stdio proc tty", NULL) == -1) 1971 fatal_f("pledge(): %s", strerror(errno)); 1972#endif 1973 1974 ssh_signal(SIGHUP, control_client_sighandler); 1975 ssh_signal(SIGINT, control_client_sighandler); 1976 ssh_signal(SIGTERM, control_client_sighandler); 1977 ssh_signal(SIGWINCH, control_client_sigrelay); 1978 1979 rawmode = tty_flag; 1980 if (tty_flag) 1981 enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 1982 1983 /* 1984 * Stick around until the controlee closes the client_fd. 1985 * Before it does, it is expected to write an exit message. 1986 * This process must read the value and wait for the closure of 1987 * the client_fd; if this one closes early, the multiplex master will 1988 * terminate early too (possibly losing data). 1989 */ 1990 for (exitval = 255, exitval_seen = 0;;) { 1991 sshbuf_reset(m); 1992 if (mux_client_read_packet(fd, m) != 0) 1993 break; 1994 if ((r = sshbuf_get_u32(m, &type)) != 0) 1995 fatal_fr(r, "parse type"); 1996 switch (type) { 1997 case MUX_S_TTY_ALLOC_FAIL: 1998 if ((r = sshbuf_get_u32(m, &esid)) != 0) 1999 fatal_fr(r, "parse session ID"); 2000 if (esid != sid) 2001 fatal_f("tty alloc fail on unknown session: " 2002 "my id %u theirs %u", sid, esid); 2003 leave_raw_mode(options.request_tty == 2004 REQUEST_TTY_FORCE); 2005 rawmode = 0; 2006 continue; 2007 case MUX_S_EXIT_MESSAGE: 2008 if ((r = sshbuf_get_u32(m, &esid)) != 0) 2009 fatal_fr(r, "parse session ID"); 2010 if (esid != sid) 2011 fatal_f("exit on unknown session: " 2012 "my id %u theirs %u", sid, esid); 2013 if (exitval_seen) 2014 fatal_f("exitval sent twice"); 2015 if ((r = sshbuf_get_u32(m, &exitval)) != 0) 2016 fatal_fr(r, "parse exitval"); 2017 exitval_seen = 1; 2018 continue; 2019 default: 2020 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2021 fatal_fr(r, "parse error message"); 2022 fatal_f("master returned error: %s", e); 2023 } 2024 } 2025 2026 close(fd); 2027 if (rawmode) 2028 leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); 2029 2030 if (muxclient_terminate) { 2031 debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); 2032 exitval = 255; 2033 } else if (!exitval_seen) { 2034 debug2("Control master terminated unexpectedly"); 2035 exitval = 255; 2036 } else 2037 debug2("Received exit status from master %d", exitval); 2038 2039 if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) 2040 fprintf(stderr, "Shared connection to %s closed.\r\n", host); 2041 2042 exit(exitval); 2043} 2044 2045static int 2046mux_client_proxy(int fd) 2047{ 2048 struct sshbuf *m; 2049 char *e; 2050 u_int type, rid; 2051 int r; 2052 2053 if ((m = sshbuf_new()) == NULL) 2054 fatal_f("sshbuf_new"); 2055 if ((r = sshbuf_put_u32(m, MUX_C_PROXY)) != 0 || 2056 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2057 fatal_fr(r, "request"); 2058 if (mux_client_write_packet(fd, m) != 0) 2059 fatal_f("write packet: %s", strerror(errno)); 2060 2061 sshbuf_reset(m); 2062 2063 /* Read their reply */ 2064 if (mux_client_read_packet(fd, m) != 0) { 2065 sshbuf_free(m); 2066 return 0; 2067 } 2068 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2069 (r = sshbuf_get_u32(m, &rid)) != 0) 2070 fatal_fr(r, "parse"); 2071 if (rid != muxclient_request_id) 2072 fatal_f("out of sequence reply: my id %u theirs %u", 2073 muxclient_request_id, rid); 2074 if (type != MUX_S_PROXY) { 2075 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2076 fatal_fr(r, "parse error message"); 2077 fatal_f("master returned error: %s", e); 2078 } 2079 sshbuf_free(m); 2080 2081 debug3_f("done"); 2082 muxclient_request_id++; 2083 return 0; 2084} 2085 2086static int 2087mux_client_request_stdio_fwd(int fd) 2088{ 2089 struct sshbuf *m; 2090 char *e; 2091 u_int type, rid, sid; 2092 int r; 2093 2094 debug3_f("entering"); 2095 2096 if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { 2097 error_f("master alive request failed"); 2098 return -1; 2099 } 2100 2101 ssh_signal(SIGPIPE, SIG_IGN); 2102 2103 if (stdin_null_flag && stdfd_devnull(1, 0, 0) == -1) 2104 fatal_f("stdfd_devnull failed"); 2105 2106 if ((m = sshbuf_new()) == NULL) 2107 fatal_f("sshbuf_new"); 2108 if ((r = sshbuf_put_u32(m, MUX_C_NEW_STDIO_FWD)) != 0 || 2109 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0 || 2110 (r = sshbuf_put_string(m, NULL, 0)) != 0 || /* reserved */ 2111 (r = sshbuf_put_cstring(m, options.stdio_forward_host)) != 0 || 2112 (r = sshbuf_put_u32(m, options.stdio_forward_port)) != 0) 2113 fatal_fr(r, "request"); 2114 2115 if (mux_client_write_packet(fd, m) != 0) 2116 fatal_f("write packet: %s", strerror(errno)); 2117 2118 /* Send the stdio file descriptors */ 2119 if (mm_send_fd(fd, STDIN_FILENO) == -1 || 2120 mm_send_fd(fd, STDOUT_FILENO) == -1) 2121 fatal_f("send fds failed"); 2122 2123#ifdef __OpenBSD__ 2124 if (pledge("stdio proc tty", NULL) == -1) 2125 fatal_f("pledge(): %s", strerror(errno)); 2126#endif 2127 2128 debug3_f("stdio forward request sent"); 2129 2130 /* Read their reply */ 2131 sshbuf_reset(m); 2132 2133 if (mux_client_read_packet(fd, m) != 0) { 2134 error_f("read from master failed: %s", strerror(errno)); 2135 sshbuf_free(m); 2136 return -1; 2137 } 2138 2139 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2140 (r = sshbuf_get_u32(m, &rid)) != 0) 2141 fatal_fr(r, "parse"); 2142 if (rid != muxclient_request_id) 2143 fatal_f("out of sequence reply: my id %u theirs %u", 2144 muxclient_request_id, rid); 2145 switch (type) { 2146 case MUX_S_SESSION_OPENED: 2147 if ((r = sshbuf_get_u32(m, &sid)) != 0) 2148 fatal_fr(r, "parse session ID"); 2149 debug_f("master session id: %u", sid); 2150 break; 2151 case MUX_S_PERMISSION_DENIED: 2152 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2153 fatal_fr(r, "parse error message"); 2154 sshbuf_free(m); 2155 fatal("Master refused stdio forwarding request: %s", e); 2156 case MUX_S_FAILURE: 2157 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2158 fatal_fr(r, "parse error message"); 2159 sshbuf_free(m); 2160 fatal("Stdio forwarding request failed: %s", e); 2161 default: 2162 sshbuf_free(m); 2163 error_f("unexpected response from master 0x%08x", type); 2164 return -1; 2165 } 2166 muxclient_request_id++; 2167 2168 ssh_signal(SIGHUP, control_client_sighandler); 2169 ssh_signal(SIGINT, control_client_sighandler); 2170 ssh_signal(SIGTERM, control_client_sighandler); 2171 ssh_signal(SIGWINCH, control_client_sigrelay); 2172 2173 /* 2174 * Stick around until the controlee closes the client_fd. 2175 */ 2176 sshbuf_reset(m); 2177 if (mux_client_read_packet(fd, m) != 0) { 2178 if (errno == EPIPE || 2179 (errno == EINTR && muxclient_terminate != 0)) 2180 return 0; 2181 fatal_f("mux_client_read_packet: %s", strerror(errno)); 2182 } 2183 fatal_f("master returned unexpected message %u", type); 2184} 2185 2186static void 2187mux_client_request_stop_listening(int fd) 2188{ 2189 struct sshbuf *m; 2190 char *e; 2191 u_int type, rid; 2192 int r; 2193 2194 debug3_f("entering"); 2195 2196 if ((m = sshbuf_new()) == NULL) 2197 fatal_f("sshbuf_new"); 2198 if ((r = sshbuf_put_u32(m, MUX_C_STOP_LISTENING)) != 0 || 2199 (r = sshbuf_put_u32(m, muxclient_request_id)) != 0) 2200 fatal_fr(r, "request"); 2201 2202 if (mux_client_write_packet(fd, m) != 0) 2203 fatal_f("write packet: %s", strerror(errno)); 2204 2205 sshbuf_reset(m); 2206 2207 /* Read their reply */ 2208 if (mux_client_read_packet(fd, m) != 0) 2209 fatal_f("read from master failed: %s", strerror(errno)); 2210 2211 if ((r = sshbuf_get_u32(m, &type)) != 0 || 2212 (r = sshbuf_get_u32(m, &rid)) != 0) 2213 fatal_fr(r, "parse"); 2214 if (rid != muxclient_request_id) 2215 fatal_f("out of sequence reply: my id %u theirs %u", 2216 muxclient_request_id, rid); 2217 2218 switch (type) { 2219 case MUX_S_OK: 2220 break; 2221 case MUX_S_PERMISSION_DENIED: 2222 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2223 fatal_fr(r, "parse error message"); 2224 fatal("Master refused stop listening request: %s", e); 2225 case MUX_S_FAILURE: 2226 if ((r = sshbuf_get_cstring(m, &e, NULL)) != 0) 2227 fatal_fr(r, "parse error message"); 2228 fatal_f("stop listening request failed: %s", e); 2229 default: 2230 fatal_f("unexpected response from master 0x%08x", type); 2231 } 2232 sshbuf_free(m); 2233 muxclient_request_id++; 2234} 2235 2236/* Multiplex client main loop. */ 2237int 2238muxclient(const char *path) 2239{ 2240 struct sockaddr_un addr; 2241 int sock; 2242 u_int pid; 2243 2244 if (muxclient_command == 0) { 2245 if (options.stdio_forward_host != NULL) 2246 muxclient_command = SSHMUX_COMMAND_STDIO_FWD; 2247 else 2248 muxclient_command = SSHMUX_COMMAND_OPEN; 2249 } 2250 2251 switch (options.control_master) { 2252 case SSHCTL_MASTER_AUTO: 2253 case SSHCTL_MASTER_AUTO_ASK: 2254 debug("auto-mux: Trying existing master"); 2255 /* FALLTHROUGH */ 2256 case SSHCTL_MASTER_NO: 2257 break; 2258 default: 2259 return -1; 2260 } 2261 2262 memset(&addr, '\0', sizeof(addr)); 2263 addr.sun_family = AF_UNIX; 2264 2265 if (strlcpy(addr.sun_path, path, 2266 sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) 2267 fatal("ControlPath too long ('%s' >= %u bytes)", path, 2268 (unsigned int)sizeof(addr.sun_path)); 2269 2270 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) 2271 fatal_f("socket(): %s", strerror(errno)); 2272 2273 if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { 2274 switch (muxclient_command) { 2275 case SSHMUX_COMMAND_OPEN: 2276 case SSHMUX_COMMAND_STDIO_FWD: 2277 break; 2278 default: 2279 fatal("Control socket connect(%.100s): %s", path, 2280 strerror(errno)); 2281 } 2282 if (errno == ECONNREFUSED && 2283 options.control_master != SSHCTL_MASTER_NO) { 2284 debug("Stale control socket %.100s, unlinking", path); 2285 unlink(path); 2286 } else if (errno == ENOENT) { 2287 debug("Control socket \"%.100s\" does not exist", path); 2288 } else { 2289 error("Control socket connect(%.100s): %s", path, 2290 strerror(errno)); 2291 } 2292 close(sock); 2293 return -1; 2294 } 2295 set_nonblock(sock); 2296 2297 if (mux_client_hello_exchange(sock) != 0) { 2298 error_f("master hello exchange failed"); 2299 close(sock); 2300 return -1; 2301 } 2302 2303 switch (muxclient_command) { 2304 case SSHMUX_COMMAND_ALIVE_CHECK: 2305 if ((pid = mux_client_request_alive(sock)) == 0) 2306 fatal_f("master alive check failed"); 2307 fprintf(stderr, "Master running (pid=%u)\r\n", pid); 2308 exit(0); 2309 case SSHMUX_COMMAND_TERMINATE: 2310 mux_client_request_terminate(sock); 2311 if (options.log_level != SYSLOG_LEVEL_QUIET) 2312 fprintf(stderr, "Exit request sent.\r\n"); 2313 exit(0); 2314 case SSHMUX_COMMAND_FORWARD: 2315 if (mux_client_forwards(sock, 0) != 0) 2316 fatal_f("master forward request failed"); 2317 exit(0); 2318 case SSHMUX_COMMAND_OPEN: 2319 if (mux_client_forwards(sock, 0) != 0) { 2320 error_f("master forward request failed"); 2321 return -1; 2322 } 2323 mux_client_request_session(sock); 2324 return -1; 2325 case SSHMUX_COMMAND_STDIO_FWD: 2326 mux_client_request_stdio_fwd(sock); 2327 exit(0); 2328 case SSHMUX_COMMAND_STOP: 2329 mux_client_request_stop_listening(sock); 2330 if (options.log_level != SYSLOG_LEVEL_QUIET) 2331 fprintf(stderr, "Stop listening request sent.\r\n"); 2332 exit(0); 2333 case SSHMUX_COMMAND_CANCEL_FWD: 2334 if (mux_client_forwards(sock, 1) != 0) 2335 error_f("master cancel forward request failed"); 2336 exit(0); 2337 case SSHMUX_COMMAND_PROXY: 2338 mux_client_proxy(sock); 2339 return (sock); 2340 default: 2341 fatal("unrecognised muxclient_command %d", muxclient_command); 2342 } 2343} 2344