serverloop.c revision 323134
1/* $OpenBSD: serverloop.c,v 1.189 2016/12/14 00:36:34 djm Exp $ */ 2/* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * Server main loop for handling the interactive session. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * SSH2 support by Markus Friedl. 15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38#include "includes.h" 39 40#include <sys/types.h> 41#include <sys/wait.h> 42#include <sys/socket.h> 43#ifdef HAVE_SYS_TIME_H 44# include <sys/time.h> 45#endif 46 47#include <netinet/in.h> 48 49#include <errno.h> 50#include <fcntl.h> 51#include <pwd.h> 52#include <signal.h> 53#include <string.h> 54#include <termios.h> 55#include <unistd.h> 56#include <stdarg.h> 57 58#include "openbsd-compat/sys-queue.h" 59#include "xmalloc.h" 60#include "packet.h" 61#include "buffer.h" 62#include "log.h" 63#include "misc.h" 64#include "servconf.h" 65#include "canohost.h" 66#include "sshpty.h" 67#include "channels.h" 68#include "compat.h" 69#include "ssh2.h" 70#include "key.h" 71#include "cipher.h" 72#include "kex.h" 73#include "hostfile.h" 74#include "auth.h" 75#include "session.h" 76#include "dispatch.h" 77#include "auth-options.h" 78#include "serverloop.h" 79#include "ssherr.h" 80 81extern ServerOptions options; 82 83/* XXX */ 84extern Authctxt *the_authctxt; 85extern int use_privsep; 86 87static int no_more_sessions = 0; /* Disallow further sessions. */ 88 89/* 90 * This SIGCHLD kludge is used to detect when the child exits. The server 91 * will exit after that, as soon as forwarded connections have terminated. 92 */ 93 94static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 95 96/* Cleanup on signals (!use_privsep case only) */ 97static volatile sig_atomic_t received_sigterm = 0; 98 99/* prototypes */ 100static void server_init_dispatch(void); 101 102/* 103 * we write to this pipe if a SIGCHLD is caught in order to avoid 104 * the race between select() and child_terminated 105 */ 106static int notify_pipe[2]; 107static void 108notify_setup(void) 109{ 110 if (pipe(notify_pipe) < 0) { 111 error("pipe(notify_pipe) failed %s", strerror(errno)); 112 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 113 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 114 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 115 close(notify_pipe[0]); 116 close(notify_pipe[1]); 117 } else { 118 set_nonblock(notify_pipe[0]); 119 set_nonblock(notify_pipe[1]); 120 return; 121 } 122 notify_pipe[0] = -1; /* read end */ 123 notify_pipe[1] = -1; /* write end */ 124} 125static void 126notify_parent(void) 127{ 128 if (notify_pipe[1] != -1) 129 (void)write(notify_pipe[1], "", 1); 130} 131static void 132notify_prepare(fd_set *readset) 133{ 134 if (notify_pipe[0] != -1) 135 FD_SET(notify_pipe[0], readset); 136} 137static void 138notify_done(fd_set *readset) 139{ 140 char c; 141 142 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 143 while (read(notify_pipe[0], &c, 1) != -1) 144 debug2("notify_done: reading"); 145} 146 147/*ARGSUSED*/ 148static void 149sigchld_handler(int sig) 150{ 151 int save_errno = errno; 152 child_terminated = 1; 153#ifndef _UNICOS 154 mysignal(SIGCHLD, sigchld_handler); 155#endif 156 notify_parent(); 157 errno = save_errno; 158} 159 160/*ARGSUSED*/ 161static void 162sigterm_handler(int sig) 163{ 164 received_sigterm = sig; 165} 166 167static void 168client_alive_check(void) 169{ 170 int channel_id; 171 172 /* timeout, check to see how many we have had */ 173 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 174 logit("Timeout, client not responding."); 175 cleanup_exit(255); 176 } 177 178 /* 179 * send a bogus global/channel request with "wantreply", 180 * we should get back a failure 181 */ 182 if ((channel_id = channel_find_open()) == -1) { 183 packet_start(SSH2_MSG_GLOBAL_REQUEST); 184 packet_put_cstring("keepalive@openssh.com"); 185 packet_put_char(1); /* boolean: want reply */ 186 } else { 187 channel_request_start(channel_id, "keepalive@openssh.com", 1); 188 } 189 packet_send(); 190} 191 192/* 193 * Sleep in select() until we can do something. This will initialize the 194 * select masks. Upon return, the masks will indicate which descriptors 195 * have data or can accept data. Optionally, a maximum time can be specified 196 * for the duration of the wait (0 = infinite). 197 */ 198static void 199wait_until_can_do_something(int connection_in, int connection_out, 200 fd_set **readsetp, fd_set **writesetp, int *maxfdp, 201 u_int *nallocp, u_int64_t max_time_ms) 202{ 203 struct timeval tv, *tvp; 204 int ret; 205 time_t minwait_secs = 0; 206 int client_alive_scheduled = 0; 207 208 /* Allocate and update select() masks for channel descriptors. */ 209 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 210 &minwait_secs, 0); 211 212 /* XXX need proper deadline system for rekey/client alive */ 213 if (minwait_secs != 0) 214 max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000); 215 216 /* 217 * if using client_alive, set the max timeout accordingly, 218 * and indicate that this particular timeout was for client 219 * alive by setting the client_alive_scheduled flag. 220 * 221 * this could be randomized somewhat to make traffic 222 * analysis more difficult, but we're not doing it yet. 223 */ 224 if (options.client_alive_interval) { 225 uint64_t keepalive_ms = 226 (uint64_t)options.client_alive_interval * 1000; 227 228 client_alive_scheduled = 1; 229 if (max_time_ms == 0 || max_time_ms > keepalive_ms) 230 max_time_ms = keepalive_ms; 231 } 232 233#if 0 234 /* wrong: bad condition XXX */ 235 if (channel_not_very_much_buffered_data()) 236#endif 237 FD_SET(connection_in, *readsetp); 238 notify_prepare(*readsetp); 239 240 /* 241 * If we have buffered packet data going to the client, mark that 242 * descriptor. 243 */ 244 if (packet_have_data_to_write()) 245 FD_SET(connection_out, *writesetp); 246 247 /* 248 * If child has terminated and there is enough buffer space to read 249 * from it, then read as much as is available and exit. 250 */ 251 if (child_terminated && packet_not_very_much_data_to_write()) 252 if (max_time_ms == 0 || client_alive_scheduled) 253 max_time_ms = 100; 254 255 if (max_time_ms == 0) 256 tvp = NULL; 257 else { 258 tv.tv_sec = max_time_ms / 1000; 259 tv.tv_usec = 1000 * (max_time_ms % 1000); 260 tvp = &tv; 261 } 262 263 /* Wait for something to happen, or the timeout to expire. */ 264 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 265 266 if (ret == -1) { 267 memset(*readsetp, 0, *nallocp); 268 memset(*writesetp, 0, *nallocp); 269 if (errno != EINTR) 270 error("select: %.100s", strerror(errno)); 271 } else if (ret == 0 && client_alive_scheduled) 272 client_alive_check(); 273 274 notify_done(*readsetp); 275} 276 277/* 278 * Processes input from the client and the program. Input data is stored 279 * in buffers and processed later. 280 */ 281static int 282process_input(fd_set *readset, int connection_in) 283{ 284 struct ssh *ssh = active_state; /* XXX */ 285 int len; 286 char buf[16384]; 287 288 /* Read and buffer any input data from the client. */ 289 if (FD_ISSET(connection_in, readset)) { 290 len = read(connection_in, buf, sizeof(buf)); 291 if (len == 0) { 292 verbose("Connection closed by %.100s port %d", 293 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 294 return -1; 295 } else if (len < 0) { 296 if (errno != EINTR && errno != EAGAIN && 297 errno != EWOULDBLOCK) { 298 verbose("Read error from remote host " 299 "%.100s port %d: %.100s", 300 ssh_remote_ipaddr(ssh), 301 ssh_remote_port(ssh), strerror(errno)); 302 cleanup_exit(255); 303 } 304 } else { 305 /* Buffer any received data. */ 306 packet_process_incoming(buf, len); 307 } 308 } 309 return 0; 310} 311 312/* 313 * Sends data from internal buffers to client program stdin. 314 */ 315static void 316process_output(fd_set *writeset, int connection_out) 317{ 318 /* Send any buffered packet data to the client. */ 319 if (FD_ISSET(connection_out, writeset)) 320 packet_write_poll(); 321} 322 323static void 324process_buffered_input_packets(void) 325{ 326 dispatch_run(DISPATCH_NONBLOCK, NULL, active_state); 327} 328 329static void 330collect_children(void) 331{ 332 pid_t pid; 333 sigset_t oset, nset; 334 int status; 335 336 /* block SIGCHLD while we check for dead children */ 337 sigemptyset(&nset); 338 sigaddset(&nset, SIGCHLD); 339 sigprocmask(SIG_BLOCK, &nset, &oset); 340 if (child_terminated) { 341 debug("Received SIGCHLD."); 342 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 343 (pid < 0 && errno == EINTR)) 344 if (pid > 0) 345 session_close_by_pid(pid, status); 346 child_terminated = 0; 347 } 348 sigprocmask(SIG_SETMASK, &oset, NULL); 349} 350 351void 352server_loop2(Authctxt *authctxt) 353{ 354 fd_set *readset = NULL, *writeset = NULL; 355 int max_fd; 356 u_int nalloc = 0, connection_in, connection_out; 357 u_int64_t rekey_timeout_ms = 0; 358 359 debug("Entering interactive session for SSH2."); 360 361 mysignal(SIGCHLD, sigchld_handler); 362 child_terminated = 0; 363 connection_in = packet_get_connection_in(); 364 connection_out = packet_get_connection_out(); 365 366 if (!use_privsep) { 367 signal(SIGTERM, sigterm_handler); 368 signal(SIGINT, sigterm_handler); 369 signal(SIGQUIT, sigterm_handler); 370 } 371 372 notify_setup(); 373 374 max_fd = MAXIMUM(connection_in, connection_out); 375 max_fd = MAXIMUM(max_fd, notify_pipe[0]); 376 377 server_init_dispatch(); 378 379 for (;;) { 380 process_buffered_input_packets(); 381 382 if (!ssh_packet_is_rekeying(active_state) && 383 packet_not_very_much_data_to_write()) 384 channel_output_poll(); 385 if (options.rekey_interval > 0 && 386 !ssh_packet_is_rekeying(active_state)) 387 rekey_timeout_ms = packet_get_rekey_timeout() * 1000; 388 else 389 rekey_timeout_ms = 0; 390 391 wait_until_can_do_something(connection_in, connection_out, 392 &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); 393 394 if (received_sigterm) { 395 logit("Exiting on signal %d", (int)received_sigterm); 396 /* Clean up sessions, utmp, etc. */ 397 cleanup_exit(255); 398 } 399 400 collect_children(); 401 if (!ssh_packet_is_rekeying(active_state)) 402 channel_after_select(readset, writeset); 403 if (process_input(readset, connection_in) < 0) 404 break; 405 process_output(writeset, connection_out); 406 } 407 collect_children(); 408 409 free(readset); 410 free(writeset); 411 412 /* free all channels, no more reads and writes */ 413 channel_free_all(); 414 415 /* free remaining sessions, e.g. remove wtmp entries */ 416 session_destroy_all(NULL); 417} 418 419static int 420server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 421{ 422 debug("Got %d/%u for keepalive", type, seq); 423 /* 424 * reset timeout, since we got a sane answer from the client. 425 * even if this was generated by something other than 426 * the bogus CHANNEL_REQUEST we send for keepalives. 427 */ 428 packet_set_alive_timeouts(0); 429 return 0; 430} 431 432static Channel * 433server_request_direct_tcpip(void) 434{ 435 Channel *c = NULL; 436 char *target, *originator; 437 u_short target_port, originator_port; 438 439 target = packet_get_string(NULL); 440 target_port = packet_get_int(); 441 originator = packet_get_string(NULL); 442 originator_port = packet_get_int(); 443 packet_check_eom(); 444 445 debug("server_request_direct_tcpip: originator %s port %d, target %s " 446 "port %d", originator, originator_port, target, target_port); 447 448 /* XXX fine grained permissions */ 449 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && 450 !no_port_forwarding_flag && !options.disable_forwarding) { 451 c = channel_connect_to_port(target, target_port, 452 "direct-tcpip", "direct-tcpip"); 453 } else { 454 logit("refused local port forward: " 455 "originator %s port %d, target %s port %d", 456 originator, originator_port, target, target_port); 457 } 458 459 free(originator); 460 free(target); 461 462 return c; 463} 464 465static Channel * 466server_request_direct_streamlocal(void) 467{ 468 Channel *c = NULL; 469 char *target, *originator; 470 u_short originator_port; 471 472 target = packet_get_string(NULL); 473 originator = packet_get_string(NULL); 474 originator_port = packet_get_int(); 475 packet_check_eom(); 476 477 debug("server_request_direct_streamlocal: originator %s port %d, target %s", 478 originator, originator_port, target); 479 480 /* XXX fine grained permissions */ 481 if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && 482 !no_port_forwarding_flag && !options.disable_forwarding && 483 use_privsep) { 484 c = channel_connect_to_path(target, 485 "direct-streamlocal@openssh.com", "direct-streamlocal"); 486 } else { 487 logit("refused streamlocal port forward: " 488 "originator %s port %d, target %s", 489 originator, originator_port, target); 490 } 491 492 free(originator); 493 free(target); 494 495 return c; 496} 497 498static Channel * 499server_request_tun(void) 500{ 501 Channel *c = NULL; 502 int mode, tun; 503 int sock; 504 505 mode = packet_get_int(); 506 switch (mode) { 507 case SSH_TUNMODE_POINTOPOINT: 508 case SSH_TUNMODE_ETHERNET: 509 break; 510 default: 511 packet_send_debug("Unsupported tunnel device mode."); 512 return NULL; 513 } 514 if ((options.permit_tun & mode) == 0) { 515 packet_send_debug("Server has rejected tunnel device " 516 "forwarding"); 517 return NULL; 518 } 519 520 tun = packet_get_int(); 521 if (forced_tun_device != -1) { 522 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 523 goto done; 524 tun = forced_tun_device; 525 } 526 sock = tun_open(tun, mode); 527 if (sock < 0) 528 goto done; 529 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 530 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 531 c->datagram = 1; 532#if defined(SSH_TUN_FILTER) 533 if (mode == SSH_TUNMODE_POINTOPOINT) 534 channel_register_filter(c->self, sys_tun_infilter, 535 sys_tun_outfilter, NULL, NULL); 536#endif 537 538 done: 539 if (c == NULL) 540 packet_send_debug("Failed to open the tunnel device."); 541 return c; 542} 543 544static Channel * 545server_request_session(void) 546{ 547 Channel *c; 548 549 debug("input_session_request"); 550 packet_check_eom(); 551 552 if (no_more_sessions) { 553 packet_disconnect("Possible attack: attempt to open a session " 554 "after additional sessions disabled"); 555 } 556 557 /* 558 * A server session has no fd to read or write until a 559 * CHANNEL_REQUEST for a shell is made, so we set the type to 560 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 561 * CHANNEL_REQUEST messages is registered. 562 */ 563 c = channel_new("session", SSH_CHANNEL_LARVAL, 564 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 565 0, "server-session", 1); 566 if (session_open(the_authctxt, c->self) != 1) { 567 debug("session open failed, free channel %d", c->self); 568 channel_free(c); 569 return NULL; 570 } 571 channel_register_cleanup(c->self, session_close_by_channel, 0); 572 return c; 573} 574 575static int 576server_input_channel_open(int type, u_int32_t seq, void *ctxt) 577{ 578 Channel *c = NULL; 579 char *ctype; 580 int rchan; 581 u_int rmaxpack, rwindow, len; 582 583 ctype = packet_get_string(&len); 584 rchan = packet_get_int(); 585 rwindow = packet_get_int(); 586 rmaxpack = packet_get_int(); 587 588 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 589 ctype, rchan, rwindow, rmaxpack); 590 591 if (strcmp(ctype, "session") == 0) { 592 c = server_request_session(); 593 } else if (strcmp(ctype, "direct-tcpip") == 0) { 594 c = server_request_direct_tcpip(); 595 } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { 596 c = server_request_direct_streamlocal(); 597 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 598 c = server_request_tun(); 599 } 600 if (c != NULL) { 601 debug("server_input_channel_open: confirm %s", ctype); 602 c->remote_id = rchan; 603 c->remote_window = rwindow; 604 c->remote_maxpacket = rmaxpack; 605 if (c->type != SSH_CHANNEL_CONNECTING) { 606 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 607 packet_put_int(c->remote_id); 608 packet_put_int(c->self); 609 packet_put_int(c->local_window); 610 packet_put_int(c->local_maxpacket); 611 packet_send(); 612 } 613 } else { 614 debug("server_input_channel_open: failure %s", ctype); 615 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 616 packet_put_int(rchan); 617 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 618 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 619 packet_put_cstring("open failed"); 620 packet_put_cstring(""); 621 } 622 packet_send(); 623 } 624 free(ctype); 625 return 0; 626} 627 628static int 629server_input_hostkeys_prove(struct sshbuf **respp) 630{ 631 struct ssh *ssh = active_state; /* XXX */ 632 struct sshbuf *resp = NULL; 633 struct sshbuf *sigbuf = NULL; 634 struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; 635 int r, ndx, success = 0; 636 const u_char *blob; 637 u_char *sig = 0; 638 size_t blen, slen; 639 640 if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) 641 fatal("%s: sshbuf_new", __func__); 642 643 while (ssh_packet_remaining(ssh) > 0) { 644 sshkey_free(key); 645 key = NULL; 646 if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || 647 (r = sshkey_from_blob(blob, blen, &key)) != 0) { 648 error("%s: couldn't parse key: %s", 649 __func__, ssh_err(r)); 650 goto out; 651 } 652 /* 653 * Better check that this is actually one of our hostkeys 654 * before attempting to sign anything with it. 655 */ 656 if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) { 657 error("%s: unknown host %s key", 658 __func__, sshkey_type(key)); 659 goto out; 660 } 661 /* 662 * XXX refactor: make kex->sign just use an index rather 663 * than passing in public and private keys 664 */ 665 if ((key_prv = get_hostkey_by_index(ndx)) == NULL && 666 (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { 667 error("%s: can't retrieve hostkey %d", __func__, ndx); 668 goto out; 669 } 670 sshbuf_reset(sigbuf); 671 free(sig); 672 sig = NULL; 673 if ((r = sshbuf_put_cstring(sigbuf, 674 "hostkeys-prove-00@openssh.com")) != 0 || 675 (r = sshbuf_put_string(sigbuf, 676 ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || 677 (r = sshkey_puts(key, sigbuf)) != 0 || 678 (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen, 679 sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 || 680 (r = sshbuf_put_string(resp, sig, slen)) != 0) { 681 error("%s: couldn't prepare signature: %s", 682 __func__, ssh_err(r)); 683 goto out; 684 } 685 } 686 /* Success */ 687 *respp = resp; 688 resp = NULL; /* don't free it */ 689 success = 1; 690 out: 691 free(sig); 692 sshbuf_free(resp); 693 sshbuf_free(sigbuf); 694 sshkey_free(key); 695 return success; 696} 697 698static int 699server_input_global_request(int type, u_int32_t seq, void *ctxt) 700{ 701 char *rtype; 702 int want_reply; 703 int r, success = 0, allocated_listen_port = 0; 704 struct sshbuf *resp = NULL; 705 706 rtype = packet_get_string(NULL); 707 want_reply = packet_get_char(); 708 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 709 710 /* -R style forwarding */ 711 if (strcmp(rtype, "tcpip-forward") == 0) { 712 struct passwd *pw; 713 struct Forward fwd; 714 715 pw = the_authctxt->pw; 716 if (pw == NULL || !the_authctxt->valid) 717 fatal("server_input_global_request: no/invalid user"); 718 memset(&fwd, 0, sizeof(fwd)); 719 fwd.listen_host = packet_get_string(NULL); 720 fwd.listen_port = (u_short)packet_get_int(); 721 debug("server_input_global_request: tcpip-forward listen %s port %d", 722 fwd.listen_host, fwd.listen_port); 723 724 /* check permissions */ 725 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || 726 no_port_forwarding_flag || options.disable_forwarding || 727 (!want_reply && fwd.listen_port == 0) || 728 (fwd.listen_port != 0 && 729 !bind_permitted(fwd.listen_port, pw->pw_uid))) { 730 success = 0; 731 packet_send_debug("Server has disabled port forwarding."); 732 } else { 733 /* Start listening on the port */ 734 success = channel_setup_remote_fwd_listener(&fwd, 735 &allocated_listen_port, &options.fwd_opts); 736 } 737 free(fwd.listen_host); 738 if ((resp = sshbuf_new()) == NULL) 739 fatal("%s: sshbuf_new", __func__); 740 if (allocated_listen_port != 0 && 741 (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) 742 fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r)); 743 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 744 struct Forward fwd; 745 746 memset(&fwd, 0, sizeof(fwd)); 747 fwd.listen_host = packet_get_string(NULL); 748 fwd.listen_port = (u_short)packet_get_int(); 749 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 750 fwd.listen_host, fwd.listen_port); 751 752 success = channel_cancel_rport_listener(&fwd); 753 free(fwd.listen_host); 754 } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { 755 struct Forward fwd; 756 757 memset(&fwd, 0, sizeof(fwd)); 758 fwd.listen_path = packet_get_string(NULL); 759 debug("server_input_global_request: streamlocal-forward listen path %s", 760 fwd.listen_path); 761 762 /* check permissions */ 763 if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 764 || no_port_forwarding_flag || options.disable_forwarding || 765 !use_privsep) { 766 success = 0; 767 packet_send_debug("Server has disabled port forwarding."); 768 } else { 769 /* Start listening on the socket */ 770 success = channel_setup_remote_fwd_listener( 771 &fwd, NULL, &options.fwd_opts); 772 } 773 free(fwd.listen_path); 774 } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { 775 struct Forward fwd; 776 777 memset(&fwd, 0, sizeof(fwd)); 778 fwd.listen_path = packet_get_string(NULL); 779 debug("%s: cancel-streamlocal-forward path %s", __func__, 780 fwd.listen_path); 781 782 success = channel_cancel_rport_listener(&fwd); 783 free(fwd.listen_path); 784 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 785 no_more_sessions = 1; 786 success = 1; 787 } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { 788 success = server_input_hostkeys_prove(&resp); 789 } 790 if (want_reply) { 791 packet_start(success ? 792 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 793 if (success && resp != NULL) 794 ssh_packet_put_raw(active_state, sshbuf_ptr(resp), 795 sshbuf_len(resp)); 796 packet_send(); 797 packet_write_wait(); 798 } 799 free(rtype); 800 sshbuf_free(resp); 801 return 0; 802} 803 804static int 805server_input_channel_req(int type, u_int32_t seq, void *ctxt) 806{ 807 Channel *c; 808 int id, reply, success = 0; 809 char *rtype; 810 811 id = packet_get_int(); 812 rtype = packet_get_string(NULL); 813 reply = packet_get_char(); 814 815 debug("server_input_channel_req: channel %d request %s reply %d", 816 id, rtype, reply); 817 818 if ((c = channel_lookup(id)) == NULL) 819 packet_disconnect("server_input_channel_req: " 820 "unknown channel %d", id); 821 if (!strcmp(rtype, "eow@openssh.com")) { 822 packet_check_eom(); 823 chan_rcvd_eow(c); 824 } else if ((c->type == SSH_CHANNEL_LARVAL || 825 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 826 success = session_input_channel_req(c, rtype); 827 if (reply && !(c->flags & CHAN_CLOSE_SENT)) { 828 packet_start(success ? 829 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 830 packet_put_int(c->remote_id); 831 packet_send(); 832 } 833 free(rtype); 834 return 0; 835} 836 837static void 838server_init_dispatch(void) 839{ 840 debug("server_init_dispatch"); 841 dispatch_init(&dispatch_protocol_error); 842 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 843 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 844 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 845 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 846 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 847 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 848 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 849 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 850 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 851 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 852 /* client_alive */ 853 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 854 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 855 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 856 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 857 /* rekeying */ 858 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 859} 860